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TOMOYO Linux Cross Reference
Linux/fs/nilfs2/segment.c

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  1 // SPDX-License-Identifier: GPL-2.0+
  2 /*
  3  * segment.c - NILFS segment constructor.
  4  *
  5  * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
  6  *
  7  * Written by Ryusuke Konishi.
  8  *
  9  */
 10 
 11 #include <linux/pagemap.h>
 12 #include <linux/buffer_head.h>
 13 #include <linux/writeback.h>
 14 #include <linux/bitops.h>
 15 #include <linux/bio.h>
 16 #include <linux/completion.h>
 17 #include <linux/blkdev.h>
 18 #include <linux/backing-dev.h>
 19 #include <linux/freezer.h>
 20 #include <linux/kthread.h>
 21 #include <linux/crc32.h>
 22 #include <linux/pagevec.h>
 23 #include <linux/slab.h>
 24 #include <linux/sched/signal.h>
 25 
 26 #include "nilfs.h"
 27 #include "btnode.h"
 28 #include "page.h"
 29 #include "segment.h"
 30 #include "sufile.h"
 31 #include "cpfile.h"
 32 #include "ifile.h"
 33 #include "segbuf.h"
 34 
 35 
 36 /*
 37  * Segment constructor
 38  */
 39 #define SC_N_INODEVEC   16   /* Size of locally allocated inode vector */
 40 
 41 #define SC_MAX_SEGDELTA 64   /*
 42                               * Upper limit of the number of segments
 43                               * appended in collection retry loop
 44                               */
 45 
 46 /* Construction mode */
 47 enum {
 48         SC_LSEG_SR = 1, /* Make a logical segment having a super root */
 49         SC_LSEG_DSYNC,  /*
 50                          * Flush data blocks of a given file and make
 51                          * a logical segment without a super root.
 52                          */
 53         SC_FLUSH_FILE,  /*
 54                          * Flush data files, leads to segment writes without
 55                          * creating a checkpoint.
 56                          */
 57         SC_FLUSH_DAT,   /*
 58                          * Flush DAT file.  This also creates segments
 59                          * without a checkpoint.
 60                          */
 61 };
 62 
 63 /* Stage numbers of dirty block collection */
 64 enum {
 65         NILFS_ST_INIT = 0,
 66         NILFS_ST_GC,            /* Collecting dirty blocks for GC */
 67         NILFS_ST_FILE,
 68         NILFS_ST_IFILE,
 69         NILFS_ST_CPFILE,
 70         NILFS_ST_SUFILE,
 71         NILFS_ST_DAT,
 72         NILFS_ST_SR,            /* Super root */
 73         NILFS_ST_DSYNC,         /* Data sync blocks */
 74         NILFS_ST_DONE,
 75 };
 76 
 77 #define CREATE_TRACE_POINTS
 78 #include <trace/events/nilfs2.h>
 79 
 80 /*
 81  * nilfs_sc_cstage_inc(), nilfs_sc_cstage_set(), nilfs_sc_cstage_get() are
 82  * wrapper functions of stage count (nilfs_sc_info->sc_stage.scnt). Users of
 83  * the variable must use them because transition of stage count must involve
 84  * trace events (trace_nilfs2_collection_stage_transition).
 85  *
 86  * nilfs_sc_cstage_get() isn't required for the above purpose because it doesn't
 87  * produce tracepoint events. It is provided just for making the intention
 88  * clear.
 89  */
 90 static inline void nilfs_sc_cstage_inc(struct nilfs_sc_info *sci)
 91 {
 92         sci->sc_stage.scnt++;
 93         trace_nilfs2_collection_stage_transition(sci);
 94 }
 95 
 96 static inline void nilfs_sc_cstage_set(struct nilfs_sc_info *sci, int next_scnt)
 97 {
 98         sci->sc_stage.scnt = next_scnt;
 99         trace_nilfs2_collection_stage_transition(sci);
100 }
101 
102 static inline int nilfs_sc_cstage_get(struct nilfs_sc_info *sci)
103 {
104         return sci->sc_stage.scnt;
105 }
106 
107 /* State flags of collection */
108 #define NILFS_CF_NODE           0x0001  /* Collecting node blocks */
109 #define NILFS_CF_IFILE_STARTED  0x0002  /* IFILE stage has started */
110 #define NILFS_CF_SUFREED        0x0004  /* segment usages has been freed */
111 #define NILFS_CF_HISTORY_MASK   (NILFS_CF_IFILE_STARTED | NILFS_CF_SUFREED)
112 
113 /* Operations depending on the construction mode and file type */
114 struct nilfs_sc_operations {
115         int (*collect_data)(struct nilfs_sc_info *, struct buffer_head *,
116                             struct inode *);
117         int (*collect_node)(struct nilfs_sc_info *, struct buffer_head *,
118                             struct inode *);
119         int (*collect_bmap)(struct nilfs_sc_info *, struct buffer_head *,
120                             struct inode *);
121         void (*write_data_binfo)(struct nilfs_sc_info *,
122                                  struct nilfs_segsum_pointer *,
123                                  union nilfs_binfo *);
124         void (*write_node_binfo)(struct nilfs_sc_info *,
125                                  struct nilfs_segsum_pointer *,
126                                  union nilfs_binfo *);
127 };
128 
129 /*
130  * Other definitions
131  */
132 static void nilfs_segctor_start_timer(struct nilfs_sc_info *);
133 static void nilfs_segctor_do_flush(struct nilfs_sc_info *, int);
134 static void nilfs_segctor_do_immediate_flush(struct nilfs_sc_info *);
135 static void nilfs_dispose_list(struct the_nilfs *, struct list_head *, int);
136 
137 #define nilfs_cnt32_gt(a, b)   \
138         (typecheck(__u32, a) && typecheck(__u32, b) && \
139          ((__s32)(b) - (__s32)(a) < 0))
140 #define nilfs_cnt32_ge(a, b)   \
141         (typecheck(__u32, a) && typecheck(__u32, b) && \
142          ((__s32)(a) - (__s32)(b) >= 0))
143 #define nilfs_cnt32_lt(a, b)  nilfs_cnt32_gt(b, a)
144 #define nilfs_cnt32_le(a, b)  nilfs_cnt32_ge(b, a)
145 
146 static int nilfs_prepare_segment_lock(struct super_block *sb,
147                                       struct nilfs_transaction_info *ti)
148 {
149         struct nilfs_transaction_info *cur_ti = current->journal_info;
150         void *save = NULL;
151 
152         if (cur_ti) {
153                 if (cur_ti->ti_magic == NILFS_TI_MAGIC)
154                         return ++cur_ti->ti_count;
155 
156                 /*
157                  * If journal_info field is occupied by other FS,
158                  * it is saved and will be restored on
159                  * nilfs_transaction_commit().
160                  */
161                 nilfs_msg(sb, KERN_WARNING, "journal info from a different FS");
162                 save = current->journal_info;
163         }
164         if (!ti) {
165                 ti = kmem_cache_alloc(nilfs_transaction_cachep, GFP_NOFS);
166                 if (!ti)
167                         return -ENOMEM;
168                 ti->ti_flags = NILFS_TI_DYNAMIC_ALLOC;
169         } else {
170                 ti->ti_flags = 0;
171         }
172         ti->ti_count = 0;
173         ti->ti_save = save;
174         ti->ti_magic = NILFS_TI_MAGIC;
175         current->journal_info = ti;
176         return 0;
177 }
178 
179 /**
180  * nilfs_transaction_begin - start indivisible file operations.
181  * @sb: super block
182  * @ti: nilfs_transaction_info
183  * @vacancy_check: flags for vacancy rate checks
184  *
185  * nilfs_transaction_begin() acquires a reader/writer semaphore, called
186  * the segment semaphore, to make a segment construction and write tasks
187  * exclusive.  The function is used with nilfs_transaction_commit() in pairs.
188  * The region enclosed by these two functions can be nested.  To avoid a
189  * deadlock, the semaphore is only acquired or released in the outermost call.
190  *
191  * This function allocates a nilfs_transaction_info struct to keep context
192  * information on it.  It is initialized and hooked onto the current task in
193  * the outermost call.  If a pre-allocated struct is given to @ti, it is used
194  * instead; otherwise a new struct is assigned from a slab.
195  *
196  * When @vacancy_check flag is set, this function will check the amount of
197  * free space, and will wait for the GC to reclaim disk space if low capacity.
198  *
199  * Return Value: On success, 0 is returned. On error, one of the following
200  * negative error code is returned.
201  *
202  * %-ENOMEM - Insufficient memory available.
203  *
204  * %-ENOSPC - No space left on device
205  */
206 int nilfs_transaction_begin(struct super_block *sb,
207                             struct nilfs_transaction_info *ti,
208                             int vacancy_check)
209 {
210         struct the_nilfs *nilfs;
211         int ret = nilfs_prepare_segment_lock(sb, ti);
212         struct nilfs_transaction_info *trace_ti;
213 
214         if (unlikely(ret < 0))
215                 return ret;
216         if (ret > 0) {
217                 trace_ti = current->journal_info;
218 
219                 trace_nilfs2_transaction_transition(sb, trace_ti,
220                                     trace_ti->ti_count, trace_ti->ti_flags,
221                                     TRACE_NILFS2_TRANSACTION_BEGIN);
222                 return 0;
223         }
224 
225         sb_start_intwrite(sb);
226 
227         nilfs = sb->s_fs_info;
228         down_read(&nilfs->ns_segctor_sem);
229         if (vacancy_check && nilfs_near_disk_full(nilfs)) {
230                 up_read(&nilfs->ns_segctor_sem);
231                 ret = -ENOSPC;
232                 goto failed;
233         }
234 
235         trace_ti = current->journal_info;
236         trace_nilfs2_transaction_transition(sb, trace_ti, trace_ti->ti_count,
237                                             trace_ti->ti_flags,
238                                             TRACE_NILFS2_TRANSACTION_BEGIN);
239         return 0;
240 
241  failed:
242         ti = current->journal_info;
243         current->journal_info = ti->ti_save;
244         if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
245                 kmem_cache_free(nilfs_transaction_cachep, ti);
246         sb_end_intwrite(sb);
247         return ret;
248 }
249 
250 /**
251  * nilfs_transaction_commit - commit indivisible file operations.
252  * @sb: super block
253  *
254  * nilfs_transaction_commit() releases the read semaphore which is
255  * acquired by nilfs_transaction_begin(). This is only performed
256  * in outermost call of this function.  If a commit flag is set,
257  * nilfs_transaction_commit() sets a timer to start the segment
258  * constructor.  If a sync flag is set, it starts construction
259  * directly.
260  */
261 int nilfs_transaction_commit(struct super_block *sb)
262 {
263         struct nilfs_transaction_info *ti = current->journal_info;
264         struct the_nilfs *nilfs = sb->s_fs_info;
265         int err = 0;
266 
267         BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
268         ti->ti_flags |= NILFS_TI_COMMIT;
269         if (ti->ti_count > 0) {
270                 ti->ti_count--;
271                 trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
272                             ti->ti_flags, TRACE_NILFS2_TRANSACTION_COMMIT);
273                 return 0;
274         }
275         if (nilfs->ns_writer) {
276                 struct nilfs_sc_info *sci = nilfs->ns_writer;
277 
278                 if (ti->ti_flags & NILFS_TI_COMMIT)
279                         nilfs_segctor_start_timer(sci);
280                 if (atomic_read(&nilfs->ns_ndirtyblks) > sci->sc_watermark)
281                         nilfs_segctor_do_flush(sci, 0);
282         }
283         up_read(&nilfs->ns_segctor_sem);
284         trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
285                             ti->ti_flags, TRACE_NILFS2_TRANSACTION_COMMIT);
286 
287         current->journal_info = ti->ti_save;
288 
289         if (ti->ti_flags & NILFS_TI_SYNC)
290                 err = nilfs_construct_segment(sb);
291         if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
292                 kmem_cache_free(nilfs_transaction_cachep, ti);
293         sb_end_intwrite(sb);
294         return err;
295 }
296 
297 void nilfs_transaction_abort(struct super_block *sb)
298 {
299         struct nilfs_transaction_info *ti = current->journal_info;
300         struct the_nilfs *nilfs = sb->s_fs_info;
301 
302         BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
303         if (ti->ti_count > 0) {
304                 ti->ti_count--;
305                 trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
306                             ti->ti_flags, TRACE_NILFS2_TRANSACTION_ABORT);
307                 return;
308         }
309         up_read(&nilfs->ns_segctor_sem);
310 
311         trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
312                     ti->ti_flags, TRACE_NILFS2_TRANSACTION_ABORT);
313 
314         current->journal_info = ti->ti_save;
315         if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
316                 kmem_cache_free(nilfs_transaction_cachep, ti);
317         sb_end_intwrite(sb);
318 }
319 
320 void nilfs_relax_pressure_in_lock(struct super_block *sb)
321 {
322         struct the_nilfs *nilfs = sb->s_fs_info;
323         struct nilfs_sc_info *sci = nilfs->ns_writer;
324 
325         if (!sci || !sci->sc_flush_request)
326                 return;
327 
328         set_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags);
329         up_read(&nilfs->ns_segctor_sem);
330 
331         down_write(&nilfs->ns_segctor_sem);
332         if (sci->sc_flush_request &&
333             test_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags)) {
334                 struct nilfs_transaction_info *ti = current->journal_info;
335 
336                 ti->ti_flags |= NILFS_TI_WRITER;
337                 nilfs_segctor_do_immediate_flush(sci);
338                 ti->ti_flags &= ~NILFS_TI_WRITER;
339         }
340         downgrade_write(&nilfs->ns_segctor_sem);
341 }
342 
343 static void nilfs_transaction_lock(struct super_block *sb,
344                                    struct nilfs_transaction_info *ti,
345                                    int gcflag)
346 {
347         struct nilfs_transaction_info *cur_ti = current->journal_info;
348         struct the_nilfs *nilfs = sb->s_fs_info;
349         struct nilfs_sc_info *sci = nilfs->ns_writer;
350 
351         WARN_ON(cur_ti);
352         ti->ti_flags = NILFS_TI_WRITER;
353         ti->ti_count = 0;
354         ti->ti_save = cur_ti;
355         ti->ti_magic = NILFS_TI_MAGIC;
356         current->journal_info = ti;
357 
358         for (;;) {
359                 trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
360                             ti->ti_flags, TRACE_NILFS2_TRANSACTION_TRYLOCK);
361 
362                 down_write(&nilfs->ns_segctor_sem);
363                 if (!test_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags))
364                         break;
365 
366                 nilfs_segctor_do_immediate_flush(sci);
367 
368                 up_write(&nilfs->ns_segctor_sem);
369                 cond_resched();
370         }
371         if (gcflag)
372                 ti->ti_flags |= NILFS_TI_GC;
373 
374         trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
375                             ti->ti_flags, TRACE_NILFS2_TRANSACTION_LOCK);
376 }
377 
378 static void nilfs_transaction_unlock(struct super_block *sb)
379 {
380         struct nilfs_transaction_info *ti = current->journal_info;
381         struct the_nilfs *nilfs = sb->s_fs_info;
382 
383         BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
384         BUG_ON(ti->ti_count > 0);
385 
386         up_write(&nilfs->ns_segctor_sem);
387         current->journal_info = ti->ti_save;
388 
389         trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
390                             ti->ti_flags, TRACE_NILFS2_TRANSACTION_UNLOCK);
391 }
392 
393 static void *nilfs_segctor_map_segsum_entry(struct nilfs_sc_info *sci,
394                                             struct nilfs_segsum_pointer *ssp,
395                                             unsigned int bytes)
396 {
397         struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
398         unsigned int blocksize = sci->sc_super->s_blocksize;
399         void *p;
400 
401         if (unlikely(ssp->offset + bytes > blocksize)) {
402                 ssp->offset = 0;
403                 BUG_ON(NILFS_SEGBUF_BH_IS_LAST(ssp->bh,
404                                                &segbuf->sb_segsum_buffers));
405                 ssp->bh = NILFS_SEGBUF_NEXT_BH(ssp->bh);
406         }
407         p = ssp->bh->b_data + ssp->offset;
408         ssp->offset += bytes;
409         return p;
410 }
411 
412 /**
413  * nilfs_segctor_reset_segment_buffer - reset the current segment buffer
414  * @sci: nilfs_sc_info
415  */
416 static int nilfs_segctor_reset_segment_buffer(struct nilfs_sc_info *sci)
417 {
418         struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
419         struct buffer_head *sumbh;
420         unsigned int sumbytes;
421         unsigned int flags = 0;
422         int err;
423 
424         if (nilfs_doing_gc())
425                 flags = NILFS_SS_GC;
426         err = nilfs_segbuf_reset(segbuf, flags, sci->sc_seg_ctime, sci->sc_cno);
427         if (unlikely(err))
428                 return err;
429 
430         sumbh = NILFS_SEGBUF_FIRST_BH(&segbuf->sb_segsum_buffers);
431         sumbytes = segbuf->sb_sum.sumbytes;
432         sci->sc_finfo_ptr.bh = sumbh;  sci->sc_finfo_ptr.offset = sumbytes;
433         sci->sc_binfo_ptr.bh = sumbh;  sci->sc_binfo_ptr.offset = sumbytes;
434         sci->sc_blk_cnt = sci->sc_datablk_cnt = 0;
435         return 0;
436 }
437 
438 static int nilfs_segctor_feed_segment(struct nilfs_sc_info *sci)
439 {
440         sci->sc_nblk_this_inc += sci->sc_curseg->sb_sum.nblocks;
441         if (NILFS_SEGBUF_IS_LAST(sci->sc_curseg, &sci->sc_segbufs))
442                 return -E2BIG; /*
443                                 * The current segment is filled up
444                                 * (internal code)
445                                 */
446         sci->sc_curseg = NILFS_NEXT_SEGBUF(sci->sc_curseg);
447         return nilfs_segctor_reset_segment_buffer(sci);
448 }
449 
450 static int nilfs_segctor_add_super_root(struct nilfs_sc_info *sci)
451 {
452         struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
453         int err;
454 
455         if (segbuf->sb_sum.nblocks >= segbuf->sb_rest_blocks) {
456                 err = nilfs_segctor_feed_segment(sci);
457                 if (err)
458                         return err;
459                 segbuf = sci->sc_curseg;
460         }
461         err = nilfs_segbuf_extend_payload(segbuf, &segbuf->sb_super_root);
462         if (likely(!err))
463                 segbuf->sb_sum.flags |= NILFS_SS_SR;
464         return err;
465 }
466 
467 /*
468  * Functions for making segment summary and payloads
469  */
470 static int nilfs_segctor_segsum_block_required(
471         struct nilfs_sc_info *sci, const struct nilfs_segsum_pointer *ssp,
472         unsigned int binfo_size)
473 {
474         unsigned int blocksize = sci->sc_super->s_blocksize;
475         /* Size of finfo and binfo is enough small against blocksize */
476 
477         return ssp->offset + binfo_size +
478                 (!sci->sc_blk_cnt ? sizeof(struct nilfs_finfo) : 0) >
479                 blocksize;
480 }
481 
482 static void nilfs_segctor_begin_finfo(struct nilfs_sc_info *sci,
483                                       struct inode *inode)
484 {
485         sci->sc_curseg->sb_sum.nfinfo++;
486         sci->sc_binfo_ptr = sci->sc_finfo_ptr;
487         nilfs_segctor_map_segsum_entry(
488                 sci, &sci->sc_binfo_ptr, sizeof(struct nilfs_finfo));
489 
490         if (NILFS_I(inode)->i_root &&
491             !test_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags))
492                 set_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
493         /* skip finfo */
494 }
495 
496 static void nilfs_segctor_end_finfo(struct nilfs_sc_info *sci,
497                                     struct inode *inode)
498 {
499         struct nilfs_finfo *finfo;
500         struct nilfs_inode_info *ii;
501         struct nilfs_segment_buffer *segbuf;
502         __u64 cno;
503 
504         if (sci->sc_blk_cnt == 0)
505                 return;
506 
507         ii = NILFS_I(inode);
508 
509         if (test_bit(NILFS_I_GCINODE, &ii->i_state))
510                 cno = ii->i_cno;
511         else if (NILFS_ROOT_METADATA_FILE(inode->i_ino))
512                 cno = 0;
513         else
514                 cno = sci->sc_cno;
515 
516         finfo = nilfs_segctor_map_segsum_entry(sci, &sci->sc_finfo_ptr,
517                                                  sizeof(*finfo));
518         finfo->fi_ino = cpu_to_le64(inode->i_ino);
519         finfo->fi_nblocks = cpu_to_le32(sci->sc_blk_cnt);
520         finfo->fi_ndatablk = cpu_to_le32(sci->sc_datablk_cnt);
521         finfo->fi_cno = cpu_to_le64(cno);
522 
523         segbuf = sci->sc_curseg;
524         segbuf->sb_sum.sumbytes = sci->sc_binfo_ptr.offset +
525                 sci->sc_super->s_blocksize * (segbuf->sb_sum.nsumblk - 1);
526         sci->sc_finfo_ptr = sci->sc_binfo_ptr;
527         sci->sc_blk_cnt = sci->sc_datablk_cnt = 0;
528 }
529 
530 static int nilfs_segctor_add_file_block(struct nilfs_sc_info *sci,
531                                         struct buffer_head *bh,
532                                         struct inode *inode,
533                                         unsigned int binfo_size)
534 {
535         struct nilfs_segment_buffer *segbuf;
536         int required, err = 0;
537 
538  retry:
539         segbuf = sci->sc_curseg;
540         required = nilfs_segctor_segsum_block_required(
541                 sci, &sci->sc_binfo_ptr, binfo_size);
542         if (segbuf->sb_sum.nblocks + required + 1 > segbuf->sb_rest_blocks) {
543                 nilfs_segctor_end_finfo(sci, inode);
544                 err = nilfs_segctor_feed_segment(sci);
545                 if (err)
546                         return err;
547                 goto retry;
548         }
549         if (unlikely(required)) {
550                 err = nilfs_segbuf_extend_segsum(segbuf);
551                 if (unlikely(err))
552                         goto failed;
553         }
554         if (sci->sc_blk_cnt == 0)
555                 nilfs_segctor_begin_finfo(sci, inode);
556 
557         nilfs_segctor_map_segsum_entry(sci, &sci->sc_binfo_ptr, binfo_size);
558         /* Substitution to vblocknr is delayed until update_blocknr() */
559         nilfs_segbuf_add_file_buffer(segbuf, bh);
560         sci->sc_blk_cnt++;
561  failed:
562         return err;
563 }
564 
565 /*
566  * Callback functions that enumerate, mark, and collect dirty blocks
567  */
568 static int nilfs_collect_file_data(struct nilfs_sc_info *sci,
569                                    struct buffer_head *bh, struct inode *inode)
570 {
571         int err;
572 
573         err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
574         if (err < 0)
575                 return err;
576 
577         err = nilfs_segctor_add_file_block(sci, bh, inode,
578                                            sizeof(struct nilfs_binfo_v));
579         if (!err)
580                 sci->sc_datablk_cnt++;
581         return err;
582 }
583 
584 static int nilfs_collect_file_node(struct nilfs_sc_info *sci,
585                                    struct buffer_head *bh,
586                                    struct inode *inode)
587 {
588         return nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
589 }
590 
591 static int nilfs_collect_file_bmap(struct nilfs_sc_info *sci,
592                                    struct buffer_head *bh,
593                                    struct inode *inode)
594 {
595         WARN_ON(!buffer_dirty(bh));
596         return nilfs_segctor_add_file_block(sci, bh, inode, sizeof(__le64));
597 }
598 
599 static void nilfs_write_file_data_binfo(struct nilfs_sc_info *sci,
600                                         struct nilfs_segsum_pointer *ssp,
601                                         union nilfs_binfo *binfo)
602 {
603         struct nilfs_binfo_v *binfo_v = nilfs_segctor_map_segsum_entry(
604                 sci, ssp, sizeof(*binfo_v));
605         *binfo_v = binfo->bi_v;
606 }
607 
608 static void nilfs_write_file_node_binfo(struct nilfs_sc_info *sci,
609                                         struct nilfs_segsum_pointer *ssp,
610                                         union nilfs_binfo *binfo)
611 {
612         __le64 *vblocknr = nilfs_segctor_map_segsum_entry(
613                 sci, ssp, sizeof(*vblocknr));
614         *vblocknr = binfo->bi_v.bi_vblocknr;
615 }
616 
617 static const struct nilfs_sc_operations nilfs_sc_file_ops = {
618         .collect_data = nilfs_collect_file_data,
619         .collect_node = nilfs_collect_file_node,
620         .collect_bmap = nilfs_collect_file_bmap,
621         .write_data_binfo = nilfs_write_file_data_binfo,
622         .write_node_binfo = nilfs_write_file_node_binfo,
623 };
624 
625 static int nilfs_collect_dat_data(struct nilfs_sc_info *sci,
626                                   struct buffer_head *bh, struct inode *inode)
627 {
628         int err;
629 
630         err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
631         if (err < 0)
632                 return err;
633 
634         err = nilfs_segctor_add_file_block(sci, bh, inode, sizeof(__le64));
635         if (!err)
636                 sci->sc_datablk_cnt++;
637         return err;
638 }
639 
640 static int nilfs_collect_dat_bmap(struct nilfs_sc_info *sci,
641                                   struct buffer_head *bh, struct inode *inode)
642 {
643         WARN_ON(!buffer_dirty(bh));
644         return nilfs_segctor_add_file_block(sci, bh, inode,
645                                             sizeof(struct nilfs_binfo_dat));
646 }
647 
648 static void nilfs_write_dat_data_binfo(struct nilfs_sc_info *sci,
649                                        struct nilfs_segsum_pointer *ssp,
650                                        union nilfs_binfo *binfo)
651 {
652         __le64 *blkoff = nilfs_segctor_map_segsum_entry(sci, ssp,
653                                                           sizeof(*blkoff));
654         *blkoff = binfo->bi_dat.bi_blkoff;
655 }
656 
657 static void nilfs_write_dat_node_binfo(struct nilfs_sc_info *sci,
658                                        struct nilfs_segsum_pointer *ssp,
659                                        union nilfs_binfo *binfo)
660 {
661         struct nilfs_binfo_dat *binfo_dat =
662                 nilfs_segctor_map_segsum_entry(sci, ssp, sizeof(*binfo_dat));
663         *binfo_dat = binfo->bi_dat;
664 }
665 
666 static const struct nilfs_sc_operations nilfs_sc_dat_ops = {
667         .collect_data = nilfs_collect_dat_data,
668         .collect_node = nilfs_collect_file_node,
669         .collect_bmap = nilfs_collect_dat_bmap,
670         .write_data_binfo = nilfs_write_dat_data_binfo,
671         .write_node_binfo = nilfs_write_dat_node_binfo,
672 };
673 
674 static const struct nilfs_sc_operations nilfs_sc_dsync_ops = {
675         .collect_data = nilfs_collect_file_data,
676         .collect_node = NULL,
677         .collect_bmap = NULL,
678         .write_data_binfo = nilfs_write_file_data_binfo,
679         .write_node_binfo = NULL,
680 };
681 
682 static size_t nilfs_lookup_dirty_data_buffers(struct inode *inode,
683                                               struct list_head *listp,
684                                               size_t nlimit,
685                                               loff_t start, loff_t end)
686 {
687         struct address_space *mapping = inode->i_mapping;
688         struct pagevec pvec;
689         pgoff_t index = 0, last = ULONG_MAX;
690         size_t ndirties = 0;
691         int i;
692 
693         if (unlikely(start != 0 || end != LLONG_MAX)) {
694                 /*
695                  * A valid range is given for sync-ing data pages. The
696                  * range is rounded to per-page; extra dirty buffers
697                  * may be included if blocksize < pagesize.
698                  */
699                 index = start >> PAGE_SHIFT;
700                 last = end >> PAGE_SHIFT;
701         }
702         pagevec_init(&pvec);
703  repeat:
704         if (unlikely(index > last) ||
705             !pagevec_lookup_range_tag(&pvec, mapping, &index, last,
706                                 PAGECACHE_TAG_DIRTY))
707                 return ndirties;
708 
709         for (i = 0; i < pagevec_count(&pvec); i++) {
710                 struct buffer_head *bh, *head;
711                 struct page *page = pvec.pages[i];
712 
713                 lock_page(page);
714                 if (!page_has_buffers(page))
715                         create_empty_buffers(page, i_blocksize(inode), 0);
716                 unlock_page(page);
717 
718                 bh = head = page_buffers(page);
719                 do {
720                         if (!buffer_dirty(bh) || buffer_async_write(bh))
721                                 continue;
722                         get_bh(bh);
723                         list_add_tail(&bh->b_assoc_buffers, listp);
724                         ndirties++;
725                         if (unlikely(ndirties >= nlimit)) {
726                                 pagevec_release(&pvec);
727                                 cond_resched();
728                                 return ndirties;
729                         }
730                 } while (bh = bh->b_this_page, bh != head);
731         }
732         pagevec_release(&pvec);
733         cond_resched();
734         goto repeat;
735 }
736 
737 static void nilfs_lookup_dirty_node_buffers(struct inode *inode,
738                                             struct list_head *listp)
739 {
740         struct nilfs_inode_info *ii = NILFS_I(inode);
741         struct address_space *mapping = &ii->i_btnode_cache;
742         struct pagevec pvec;
743         struct buffer_head *bh, *head;
744         unsigned int i;
745         pgoff_t index = 0;
746 
747         pagevec_init(&pvec);
748 
749         while (pagevec_lookup_tag(&pvec, mapping, &index,
750                                         PAGECACHE_TAG_DIRTY)) {
751                 for (i = 0; i < pagevec_count(&pvec); i++) {
752                         bh = head = page_buffers(pvec.pages[i]);
753                         do {
754                                 if (buffer_dirty(bh) &&
755                                                 !buffer_async_write(bh)) {
756                                         get_bh(bh);
757                                         list_add_tail(&bh->b_assoc_buffers,
758                                                       listp);
759                                 }
760                                 bh = bh->b_this_page;
761                         } while (bh != head);
762                 }
763                 pagevec_release(&pvec);
764                 cond_resched();
765         }
766 }
767 
768 static void nilfs_dispose_list(struct the_nilfs *nilfs,
769                                struct list_head *head, int force)
770 {
771         struct nilfs_inode_info *ii, *n;
772         struct nilfs_inode_info *ivec[SC_N_INODEVEC], **pii;
773         unsigned int nv = 0;
774 
775         while (!list_empty(head)) {
776                 spin_lock(&nilfs->ns_inode_lock);
777                 list_for_each_entry_safe(ii, n, head, i_dirty) {
778                         list_del_init(&ii->i_dirty);
779                         if (force) {
780                                 if (unlikely(ii->i_bh)) {
781                                         brelse(ii->i_bh);
782                                         ii->i_bh = NULL;
783                                 }
784                         } else if (test_bit(NILFS_I_DIRTY, &ii->i_state)) {
785                                 set_bit(NILFS_I_QUEUED, &ii->i_state);
786                                 list_add_tail(&ii->i_dirty,
787                                               &nilfs->ns_dirty_files);
788                                 continue;
789                         }
790                         ivec[nv++] = ii;
791                         if (nv == SC_N_INODEVEC)
792                                 break;
793                 }
794                 spin_unlock(&nilfs->ns_inode_lock);
795 
796                 for (pii = ivec; nv > 0; pii++, nv--)
797                         iput(&(*pii)->vfs_inode);
798         }
799 }
800 
801 static void nilfs_iput_work_func(struct work_struct *work)
802 {
803         struct nilfs_sc_info *sci = container_of(work, struct nilfs_sc_info,
804                                                  sc_iput_work);
805         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
806 
807         nilfs_dispose_list(nilfs, &sci->sc_iput_queue, 0);
808 }
809 
810 static int nilfs_test_metadata_dirty(struct the_nilfs *nilfs,
811                                      struct nilfs_root *root)
812 {
813         int ret = 0;
814 
815         if (nilfs_mdt_fetch_dirty(root->ifile))
816                 ret++;
817         if (nilfs_mdt_fetch_dirty(nilfs->ns_cpfile))
818                 ret++;
819         if (nilfs_mdt_fetch_dirty(nilfs->ns_sufile))
820                 ret++;
821         if ((ret || nilfs_doing_gc()) && nilfs_mdt_fetch_dirty(nilfs->ns_dat))
822                 ret++;
823         return ret;
824 }
825 
826 static int nilfs_segctor_clean(struct nilfs_sc_info *sci)
827 {
828         return list_empty(&sci->sc_dirty_files) &&
829                 !test_bit(NILFS_SC_DIRTY, &sci->sc_flags) &&
830                 sci->sc_nfreesegs == 0 &&
831                 (!nilfs_doing_gc() || list_empty(&sci->sc_gc_inodes));
832 }
833 
834 static int nilfs_segctor_confirm(struct nilfs_sc_info *sci)
835 {
836         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
837         int ret = 0;
838 
839         if (nilfs_test_metadata_dirty(nilfs, sci->sc_root))
840                 set_bit(NILFS_SC_DIRTY, &sci->sc_flags);
841 
842         spin_lock(&nilfs->ns_inode_lock);
843         if (list_empty(&nilfs->ns_dirty_files) && nilfs_segctor_clean(sci))
844                 ret++;
845 
846         spin_unlock(&nilfs->ns_inode_lock);
847         return ret;
848 }
849 
850 static void nilfs_segctor_clear_metadata_dirty(struct nilfs_sc_info *sci)
851 {
852         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
853 
854         nilfs_mdt_clear_dirty(sci->sc_root->ifile);
855         nilfs_mdt_clear_dirty(nilfs->ns_cpfile);
856         nilfs_mdt_clear_dirty(nilfs->ns_sufile);
857         nilfs_mdt_clear_dirty(nilfs->ns_dat);
858 }
859 
860 static int nilfs_segctor_create_checkpoint(struct nilfs_sc_info *sci)
861 {
862         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
863         struct buffer_head *bh_cp;
864         struct nilfs_checkpoint *raw_cp;
865         int err;
866 
867         /* XXX: this interface will be changed */
868         err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, 1,
869                                           &raw_cp, &bh_cp);
870         if (likely(!err)) {
871                 /*
872                  * The following code is duplicated with cpfile.  But, it is
873                  * needed to collect the checkpoint even if it was not newly
874                  * created.
875                  */
876                 mark_buffer_dirty(bh_cp);
877                 nilfs_mdt_mark_dirty(nilfs->ns_cpfile);
878                 nilfs_cpfile_put_checkpoint(
879                         nilfs->ns_cpfile, nilfs->ns_cno, bh_cp);
880         } else
881                 WARN_ON(err == -EINVAL || err == -ENOENT);
882 
883         return err;
884 }
885 
886 static int nilfs_segctor_fill_in_checkpoint(struct nilfs_sc_info *sci)
887 {
888         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
889         struct buffer_head *bh_cp;
890         struct nilfs_checkpoint *raw_cp;
891         int err;
892 
893         err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, 0,
894                                           &raw_cp, &bh_cp);
895         if (unlikely(err)) {
896                 WARN_ON(err == -EINVAL || err == -ENOENT);
897                 goto failed_ibh;
898         }
899         raw_cp->cp_snapshot_list.ssl_next = 0;
900         raw_cp->cp_snapshot_list.ssl_prev = 0;
901         raw_cp->cp_inodes_count =
902                 cpu_to_le64(atomic64_read(&sci->sc_root->inodes_count));
903         raw_cp->cp_blocks_count =
904                 cpu_to_le64(atomic64_read(&sci->sc_root->blocks_count));
905         raw_cp->cp_nblk_inc =
906                 cpu_to_le64(sci->sc_nblk_inc + sci->sc_nblk_this_inc);
907         raw_cp->cp_create = cpu_to_le64(sci->sc_seg_ctime);
908         raw_cp->cp_cno = cpu_to_le64(nilfs->ns_cno);
909 
910         if (test_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags))
911                 nilfs_checkpoint_clear_minor(raw_cp);
912         else
913                 nilfs_checkpoint_set_minor(raw_cp);
914 
915         nilfs_write_inode_common(sci->sc_root->ifile,
916                                  &raw_cp->cp_ifile_inode, 1);
917         nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, bh_cp);
918         return 0;
919 
920  failed_ibh:
921         return err;
922 }
923 
924 static void nilfs_fill_in_file_bmap(struct inode *ifile,
925                                     struct nilfs_inode_info *ii)
926 
927 {
928         struct buffer_head *ibh;
929         struct nilfs_inode *raw_inode;
930 
931         if (test_bit(NILFS_I_BMAP, &ii->i_state)) {
932                 ibh = ii->i_bh;
933                 BUG_ON(!ibh);
934                 raw_inode = nilfs_ifile_map_inode(ifile, ii->vfs_inode.i_ino,
935                                                   ibh);
936                 nilfs_bmap_write(ii->i_bmap, raw_inode);
937                 nilfs_ifile_unmap_inode(ifile, ii->vfs_inode.i_ino, ibh);
938         }
939 }
940 
941 static void nilfs_segctor_fill_in_file_bmap(struct nilfs_sc_info *sci)
942 {
943         struct nilfs_inode_info *ii;
944 
945         list_for_each_entry(ii, &sci->sc_dirty_files, i_dirty) {
946                 nilfs_fill_in_file_bmap(sci->sc_root->ifile, ii);
947                 set_bit(NILFS_I_COLLECTED, &ii->i_state);
948         }
949 }
950 
951 static void nilfs_segctor_fill_in_super_root(struct nilfs_sc_info *sci,
952                                              struct the_nilfs *nilfs)
953 {
954         struct buffer_head *bh_sr;
955         struct nilfs_super_root *raw_sr;
956         unsigned int isz, srsz;
957 
958         bh_sr = NILFS_LAST_SEGBUF(&sci->sc_segbufs)->sb_super_root;
959         raw_sr = (struct nilfs_super_root *)bh_sr->b_data;
960         isz = nilfs->ns_inode_size;
961         srsz = NILFS_SR_BYTES(isz);
962 
963         raw_sr->sr_bytes = cpu_to_le16(srsz);
964         raw_sr->sr_nongc_ctime
965                 = cpu_to_le64(nilfs_doing_gc() ?
966                               nilfs->ns_nongc_ctime : sci->sc_seg_ctime);
967         raw_sr->sr_flags = 0;
968 
969         nilfs_write_inode_common(nilfs->ns_dat, (void *)raw_sr +
970                                  NILFS_SR_DAT_OFFSET(isz), 1);
971         nilfs_write_inode_common(nilfs->ns_cpfile, (void *)raw_sr +
972                                  NILFS_SR_CPFILE_OFFSET(isz), 1);
973         nilfs_write_inode_common(nilfs->ns_sufile, (void *)raw_sr +
974                                  NILFS_SR_SUFILE_OFFSET(isz), 1);
975         memset((void *)raw_sr + srsz, 0, nilfs->ns_blocksize - srsz);
976 }
977 
978 static void nilfs_redirty_inodes(struct list_head *head)
979 {
980         struct nilfs_inode_info *ii;
981 
982         list_for_each_entry(ii, head, i_dirty) {
983                 if (test_bit(NILFS_I_COLLECTED, &ii->i_state))
984                         clear_bit(NILFS_I_COLLECTED, &ii->i_state);
985         }
986 }
987 
988 static void nilfs_drop_collected_inodes(struct list_head *head)
989 {
990         struct nilfs_inode_info *ii;
991 
992         list_for_each_entry(ii, head, i_dirty) {
993                 if (!test_and_clear_bit(NILFS_I_COLLECTED, &ii->i_state))
994                         continue;
995 
996                 clear_bit(NILFS_I_INODE_SYNC, &ii->i_state);
997                 set_bit(NILFS_I_UPDATED, &ii->i_state);
998         }
999 }
1000 
1001 static int nilfs_segctor_apply_buffers(struct nilfs_sc_info *sci,
1002                                        struct inode *inode,
1003                                        struct list_head *listp,
1004                                        int (*collect)(struct nilfs_sc_info *,
1005                                                       struct buffer_head *,
1006                                                       struct inode *))
1007 {
1008         struct buffer_head *bh, *n;
1009         int err = 0;
1010 
1011         if (collect) {
1012                 list_for_each_entry_safe(bh, n, listp, b_assoc_buffers) {
1013                         list_del_init(&bh->b_assoc_buffers);
1014                         err = collect(sci, bh, inode);
1015                         brelse(bh);
1016                         if (unlikely(err))
1017                                 goto dispose_buffers;
1018                 }
1019                 return 0;
1020         }
1021 
1022  dispose_buffers:
1023         while (!list_empty(listp)) {
1024                 bh = list_first_entry(listp, struct buffer_head,
1025                                       b_assoc_buffers);
1026                 list_del_init(&bh->b_assoc_buffers);
1027                 brelse(bh);
1028         }
1029         return err;
1030 }
1031 
1032 static size_t nilfs_segctor_buffer_rest(struct nilfs_sc_info *sci)
1033 {
1034         /* Remaining number of blocks within segment buffer */
1035         return sci->sc_segbuf_nblocks -
1036                 (sci->sc_nblk_this_inc + sci->sc_curseg->sb_sum.nblocks);
1037 }
1038 
1039 static int nilfs_segctor_scan_file(struct nilfs_sc_info *sci,
1040                                    struct inode *inode,
1041                                    const struct nilfs_sc_operations *sc_ops)
1042 {
1043         LIST_HEAD(data_buffers);
1044         LIST_HEAD(node_buffers);
1045         int err;
1046 
1047         if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
1048                 size_t n, rest = nilfs_segctor_buffer_rest(sci);
1049 
1050                 n = nilfs_lookup_dirty_data_buffers(
1051                         inode, &data_buffers, rest + 1, 0, LLONG_MAX);
1052                 if (n > rest) {
1053                         err = nilfs_segctor_apply_buffers(
1054                                 sci, inode, &data_buffers,
1055                                 sc_ops->collect_data);
1056                         BUG_ON(!err); /* always receive -E2BIG or true error */
1057                         goto break_or_fail;
1058                 }
1059         }
1060         nilfs_lookup_dirty_node_buffers(inode, &node_buffers);
1061 
1062         if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
1063                 err = nilfs_segctor_apply_buffers(
1064                         sci, inode, &data_buffers, sc_ops->collect_data);
1065                 if (unlikely(err)) {
1066                         /* dispose node list */
1067                         nilfs_segctor_apply_buffers(
1068                                 sci, inode, &node_buffers, NULL);
1069                         goto break_or_fail;
1070                 }
1071                 sci->sc_stage.flags |= NILFS_CF_NODE;
1072         }
1073         /* Collect node */
1074         err = nilfs_segctor_apply_buffers(
1075                 sci, inode, &node_buffers, sc_ops->collect_node);
1076         if (unlikely(err))
1077                 goto break_or_fail;
1078 
1079         nilfs_bmap_lookup_dirty_buffers(NILFS_I(inode)->i_bmap, &node_buffers);
1080         err = nilfs_segctor_apply_buffers(
1081                 sci, inode, &node_buffers, sc_ops->collect_bmap);
1082         if (unlikely(err))
1083                 goto break_or_fail;
1084 
1085         nilfs_segctor_end_finfo(sci, inode);
1086         sci->sc_stage.flags &= ~NILFS_CF_NODE;
1087 
1088  break_or_fail:
1089         return err;
1090 }
1091 
1092 static int nilfs_segctor_scan_file_dsync(struct nilfs_sc_info *sci,
1093                                          struct inode *inode)
1094 {
1095         LIST_HEAD(data_buffers);
1096         size_t n, rest = nilfs_segctor_buffer_rest(sci);
1097         int err;
1098 
1099         n = nilfs_lookup_dirty_data_buffers(inode, &data_buffers, rest + 1,
1100                                             sci->sc_dsync_start,
1101                                             sci->sc_dsync_end);
1102 
1103         err = nilfs_segctor_apply_buffers(sci, inode, &data_buffers,
1104                                           nilfs_collect_file_data);
1105         if (!err) {
1106                 nilfs_segctor_end_finfo(sci, inode);
1107                 BUG_ON(n > rest);
1108                 /* always receive -E2BIG or true error if n > rest */
1109         }
1110         return err;
1111 }
1112 
1113 static int nilfs_segctor_collect_blocks(struct nilfs_sc_info *sci, int mode)
1114 {
1115         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
1116         struct list_head *head;
1117         struct nilfs_inode_info *ii;
1118         size_t ndone;
1119         int err = 0;
1120 
1121         switch (nilfs_sc_cstage_get(sci)) {
1122         case NILFS_ST_INIT:
1123                 /* Pre-processes */
1124                 sci->sc_stage.flags = 0;
1125 
1126                 if (!test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags)) {
1127                         sci->sc_nblk_inc = 0;
1128                         sci->sc_curseg->sb_sum.flags = NILFS_SS_LOGBGN;
1129                         if (mode == SC_LSEG_DSYNC) {
1130                                 nilfs_sc_cstage_set(sci, NILFS_ST_DSYNC);
1131                                 goto dsync_mode;
1132                         }
1133                 }
1134 
1135                 sci->sc_stage.dirty_file_ptr = NULL;
1136                 sci->sc_stage.gc_inode_ptr = NULL;
1137                 if (mode == SC_FLUSH_DAT) {
1138                         nilfs_sc_cstage_set(sci, NILFS_ST_DAT);
1139                         goto dat_stage;
1140                 }
1141                 nilfs_sc_cstage_inc(sci);  /* Fall through */
1142         case NILFS_ST_GC:
1143                 if (nilfs_doing_gc()) {
1144                         head = &sci->sc_gc_inodes;
1145                         ii = list_prepare_entry(sci->sc_stage.gc_inode_ptr,
1146                                                 head, i_dirty);
1147                         list_for_each_entry_continue(ii, head, i_dirty) {
1148                                 err = nilfs_segctor_scan_file(
1149                                         sci, &ii->vfs_inode,
1150                                         &nilfs_sc_file_ops);
1151                                 if (unlikely(err)) {
1152                                         sci->sc_stage.gc_inode_ptr = list_entry(
1153                                                 ii->i_dirty.prev,
1154                                                 struct nilfs_inode_info,
1155                                                 i_dirty);
1156                                         goto break_or_fail;
1157                                 }
1158                                 set_bit(NILFS_I_COLLECTED, &ii->i_state);
1159                         }
1160                         sci->sc_stage.gc_inode_ptr = NULL;
1161                 }
1162                 nilfs_sc_cstage_inc(sci);  /* Fall through */
1163         case NILFS_ST_FILE:
1164                 head = &sci->sc_dirty_files;
1165                 ii = list_prepare_entry(sci->sc_stage.dirty_file_ptr, head,
1166                                         i_dirty);
1167                 list_for_each_entry_continue(ii, head, i_dirty) {
1168                         clear_bit(NILFS_I_DIRTY, &ii->i_state);
1169 
1170                         err = nilfs_segctor_scan_file(sci, &ii->vfs_inode,
1171                                                       &nilfs_sc_file_ops);
1172                         if (unlikely(err)) {
1173                                 sci->sc_stage.dirty_file_ptr =
1174                                         list_entry(ii->i_dirty.prev,
1175                                                    struct nilfs_inode_info,
1176                                                    i_dirty);
1177                                 goto break_or_fail;
1178                         }
1179                         /* sci->sc_stage.dirty_file_ptr = NILFS_I(inode); */
1180                         /* XXX: required ? */
1181                 }
1182                 sci->sc_stage.dirty_file_ptr = NULL;
1183                 if (mode == SC_FLUSH_FILE) {
1184                         nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1185                         return 0;
1186                 }
1187                 nilfs_sc_cstage_inc(sci);
1188                 sci->sc_stage.flags |= NILFS_CF_IFILE_STARTED;
1189                 /* Fall through */
1190         case NILFS_ST_IFILE:
1191                 err = nilfs_segctor_scan_file(sci, sci->sc_root->ifile,
1192                                               &nilfs_sc_file_ops);
1193                 if (unlikely(err))
1194                         break;
1195                 nilfs_sc_cstage_inc(sci);
1196                 /* Creating a checkpoint */
1197                 err = nilfs_segctor_create_checkpoint(sci);
1198                 if (unlikely(err))
1199                         break;
1200                 /* Fall through */
1201         case NILFS_ST_CPFILE:
1202                 err = nilfs_segctor_scan_file(sci, nilfs->ns_cpfile,
1203                                               &nilfs_sc_file_ops);
1204                 if (unlikely(err))
1205                         break;
1206                 nilfs_sc_cstage_inc(sci);  /* Fall through */
1207         case NILFS_ST_SUFILE:
1208                 err = nilfs_sufile_freev(nilfs->ns_sufile, sci->sc_freesegs,
1209                                          sci->sc_nfreesegs, &ndone);
1210                 if (unlikely(err)) {
1211                         nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1212                                                   sci->sc_freesegs, ndone,
1213                                                   NULL);
1214                         break;
1215                 }
1216                 sci->sc_stage.flags |= NILFS_CF_SUFREED;
1217 
1218                 err = nilfs_segctor_scan_file(sci, nilfs->ns_sufile,
1219                                               &nilfs_sc_file_ops);
1220                 if (unlikely(err))
1221                         break;
1222                 nilfs_sc_cstage_inc(sci);  /* Fall through */
1223         case NILFS_ST_DAT:
1224  dat_stage:
1225                 err = nilfs_segctor_scan_file(sci, nilfs->ns_dat,
1226                                               &nilfs_sc_dat_ops);
1227                 if (unlikely(err))
1228                         break;
1229                 if (mode == SC_FLUSH_DAT) {
1230                         nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1231                         return 0;
1232                 }
1233                 nilfs_sc_cstage_inc(sci);  /* Fall through */
1234         case NILFS_ST_SR:
1235                 if (mode == SC_LSEG_SR) {
1236                         /* Appending a super root */
1237                         err = nilfs_segctor_add_super_root(sci);
1238                         if (unlikely(err))
1239                                 break;
1240                 }
1241                 /* End of a logical segment */
1242                 sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
1243                 nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1244                 return 0;
1245         case NILFS_ST_DSYNC:
1246  dsync_mode:
1247                 sci->sc_curseg->sb_sum.flags |= NILFS_SS_SYNDT;
1248                 ii = sci->sc_dsync_inode;
1249                 if (!test_bit(NILFS_I_BUSY, &ii->i_state))
1250                         break;
1251 
1252                 err = nilfs_segctor_scan_file_dsync(sci, &ii->vfs_inode);
1253                 if (unlikely(err))
1254                         break;
1255                 sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
1256                 nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1257                 return 0;
1258         case NILFS_ST_DONE:
1259                 return 0;
1260         default:
1261                 BUG();
1262         }
1263 
1264  break_or_fail:
1265         return err;
1266 }
1267 
1268 /**
1269  * nilfs_segctor_begin_construction - setup segment buffer to make a new log
1270  * @sci: nilfs_sc_info
1271  * @nilfs: nilfs object
1272  */
1273 static int nilfs_segctor_begin_construction(struct nilfs_sc_info *sci,
1274                                             struct the_nilfs *nilfs)
1275 {
1276         struct nilfs_segment_buffer *segbuf, *prev;
1277         __u64 nextnum;
1278         int err, alloc = 0;
1279 
1280         segbuf = nilfs_segbuf_new(sci->sc_super);
1281         if (unlikely(!segbuf))
1282                 return -ENOMEM;
1283 
1284         if (list_empty(&sci->sc_write_logs)) {
1285                 nilfs_segbuf_map(segbuf, nilfs->ns_segnum,
1286                                  nilfs->ns_pseg_offset, nilfs);
1287                 if (segbuf->sb_rest_blocks < NILFS_PSEG_MIN_BLOCKS) {
1288                         nilfs_shift_to_next_segment(nilfs);
1289                         nilfs_segbuf_map(segbuf, nilfs->ns_segnum, 0, nilfs);
1290                 }
1291 
1292                 segbuf->sb_sum.seg_seq = nilfs->ns_seg_seq;
1293                 nextnum = nilfs->ns_nextnum;
1294 
1295                 if (nilfs->ns_segnum == nilfs->ns_nextnum)
1296                         /* Start from the head of a new full segment */
1297                         alloc++;
1298         } else {
1299                 /* Continue logs */
1300                 prev = NILFS_LAST_SEGBUF(&sci->sc_write_logs);
1301                 nilfs_segbuf_map_cont(segbuf, prev);
1302                 segbuf->sb_sum.seg_seq = prev->sb_sum.seg_seq;
1303                 nextnum = prev->sb_nextnum;
1304 
1305                 if (segbuf->sb_rest_blocks < NILFS_PSEG_MIN_BLOCKS) {
1306                         nilfs_segbuf_map(segbuf, prev->sb_nextnum, 0, nilfs);
1307                         segbuf->sb_sum.seg_seq++;
1308                         alloc++;
1309                 }
1310         }
1311 
1312         err = nilfs_sufile_mark_dirty(nilfs->ns_sufile, segbuf->sb_segnum);
1313         if (err)
1314                 goto failed;
1315 
1316         if (alloc) {
1317                 err = nilfs_sufile_alloc(nilfs->ns_sufile, &nextnum);
1318                 if (err)
1319                         goto failed;
1320         }
1321         nilfs_segbuf_set_next_segnum(segbuf, nextnum, nilfs);
1322 
1323         BUG_ON(!list_empty(&sci->sc_segbufs));
1324         list_add_tail(&segbuf->sb_list, &sci->sc_segbufs);
1325         sci->sc_segbuf_nblocks = segbuf->sb_rest_blocks;
1326         return 0;
1327 
1328  failed:
1329         nilfs_segbuf_free(segbuf);
1330         return err;
1331 }
1332 
1333 static int nilfs_segctor_extend_segments(struct nilfs_sc_info *sci,
1334                                          struct the_nilfs *nilfs, int nadd)
1335 {
1336         struct nilfs_segment_buffer *segbuf, *prev;
1337         struct inode *sufile = nilfs->ns_sufile;
1338         __u64 nextnextnum;
1339         LIST_HEAD(list);
1340         int err, ret, i;
1341 
1342         prev = NILFS_LAST_SEGBUF(&sci->sc_segbufs);
1343         /*
1344          * Since the segment specified with nextnum might be allocated during
1345          * the previous construction, the buffer including its segusage may
1346          * not be dirty.  The following call ensures that the buffer is dirty
1347          * and will pin the buffer on memory until the sufile is written.
1348          */
1349         err = nilfs_sufile_mark_dirty(sufile, prev->sb_nextnum);
1350         if (unlikely(err))
1351                 return err;
1352 
1353         for (i = 0; i < nadd; i++) {
1354                 /* extend segment info */
1355                 err = -ENOMEM;
1356                 segbuf = nilfs_segbuf_new(sci->sc_super);
1357                 if (unlikely(!segbuf))
1358                         goto failed;
1359 
1360                 /* map this buffer to region of segment on-disk */
1361                 nilfs_segbuf_map(segbuf, prev->sb_nextnum, 0, nilfs);
1362                 sci->sc_segbuf_nblocks += segbuf->sb_rest_blocks;
1363 
1364                 /* allocate the next next full segment */
1365                 err = nilfs_sufile_alloc(sufile, &nextnextnum);
1366                 if (unlikely(err))
1367                         goto failed_segbuf;
1368 
1369                 segbuf->sb_sum.seg_seq = prev->sb_sum.seg_seq + 1;
1370                 nilfs_segbuf_set_next_segnum(segbuf, nextnextnum, nilfs);
1371 
1372                 list_add_tail(&segbuf->sb_list, &list);
1373                 prev = segbuf;
1374         }
1375         list_splice_tail(&list, &sci->sc_segbufs);
1376         return 0;
1377 
1378  failed_segbuf:
1379         nilfs_segbuf_free(segbuf);
1380  failed:
1381         list_for_each_entry(segbuf, &list, sb_list) {
1382                 ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1383                 WARN_ON(ret); /* never fails */
1384         }
1385         nilfs_destroy_logs(&list);
1386         return err;
1387 }
1388 
1389 static void nilfs_free_incomplete_logs(struct list_head *logs,
1390                                        struct the_nilfs *nilfs)
1391 {
1392         struct nilfs_segment_buffer *segbuf, *prev;
1393         struct inode *sufile = nilfs->ns_sufile;
1394         int ret;
1395 
1396         segbuf = NILFS_FIRST_SEGBUF(logs);
1397         if (nilfs->ns_nextnum != segbuf->sb_nextnum) {
1398                 ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1399                 WARN_ON(ret); /* never fails */
1400         }
1401         if (atomic_read(&segbuf->sb_err)) {
1402                 /* Case 1: The first segment failed */
1403                 if (segbuf->sb_pseg_start != segbuf->sb_fseg_start)
1404                         /*
1405                          * Case 1a:  Partial segment appended into an existing
1406                          * segment
1407                          */
1408                         nilfs_terminate_segment(nilfs, segbuf->sb_fseg_start,
1409                                                 segbuf->sb_fseg_end);
1410                 else /* Case 1b:  New full segment */
1411                         set_nilfs_discontinued(nilfs);
1412         }
1413 
1414         prev = segbuf;
1415         list_for_each_entry_continue(segbuf, logs, sb_list) {
1416                 if (prev->sb_nextnum != segbuf->sb_nextnum) {
1417                         ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1418                         WARN_ON(ret); /* never fails */
1419                 }
1420                 if (atomic_read(&segbuf->sb_err) &&
1421                     segbuf->sb_segnum != nilfs->ns_nextnum)
1422                         /* Case 2: extended segment (!= next) failed */
1423                         nilfs_sufile_set_error(sufile, segbuf->sb_segnum);
1424                 prev = segbuf;
1425         }
1426 }
1427 
1428 static void nilfs_segctor_update_segusage(struct nilfs_sc_info *sci,
1429                                           struct inode *sufile)
1430 {
1431         struct nilfs_segment_buffer *segbuf;
1432         unsigned long live_blocks;
1433         int ret;
1434 
1435         list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1436                 live_blocks = segbuf->sb_sum.nblocks +
1437                         (segbuf->sb_pseg_start - segbuf->sb_fseg_start);
1438                 ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1439                                                      live_blocks,
1440                                                      sci->sc_seg_ctime);
1441                 WARN_ON(ret); /* always succeed because the segusage is dirty */
1442         }
1443 }
1444 
1445 static void nilfs_cancel_segusage(struct list_head *logs, struct inode *sufile)
1446 {
1447         struct nilfs_segment_buffer *segbuf;
1448         int ret;
1449 
1450         segbuf = NILFS_FIRST_SEGBUF(logs);
1451         ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1452                                              segbuf->sb_pseg_start -
1453                                              segbuf->sb_fseg_start, 0);
1454         WARN_ON(ret); /* always succeed because the segusage is dirty */
1455 
1456         list_for_each_entry_continue(segbuf, logs, sb_list) {
1457                 ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1458                                                      0, 0);
1459                 WARN_ON(ret); /* always succeed */
1460         }
1461 }
1462 
1463 static void nilfs_segctor_truncate_segments(struct nilfs_sc_info *sci,
1464                                             struct nilfs_segment_buffer *last,
1465                                             struct inode *sufile)
1466 {
1467         struct nilfs_segment_buffer *segbuf = last;
1468         int ret;
1469 
1470         list_for_each_entry_continue(segbuf, &sci->sc_segbufs, sb_list) {
1471                 sci->sc_segbuf_nblocks -= segbuf->sb_rest_blocks;
1472                 ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1473                 WARN_ON(ret);
1474         }
1475         nilfs_truncate_logs(&sci->sc_segbufs, last);
1476 }
1477 
1478 
1479 static int nilfs_segctor_collect(struct nilfs_sc_info *sci,
1480                                  struct the_nilfs *nilfs, int mode)
1481 {
1482         struct nilfs_cstage prev_stage = sci->sc_stage;
1483         int err, nadd = 1;
1484 
1485         /* Collection retry loop */
1486         for (;;) {
1487                 sci->sc_nblk_this_inc = 0;
1488                 sci->sc_curseg = NILFS_FIRST_SEGBUF(&sci->sc_segbufs);
1489 
1490                 err = nilfs_segctor_reset_segment_buffer(sci);
1491                 if (unlikely(err))
1492                         goto failed;
1493 
1494                 err = nilfs_segctor_collect_blocks(sci, mode);
1495                 sci->sc_nblk_this_inc += sci->sc_curseg->sb_sum.nblocks;
1496                 if (!err)
1497                         break;
1498 
1499                 if (unlikely(err != -E2BIG))
1500                         goto failed;
1501 
1502                 /* The current segment is filled up */
1503                 if (mode != SC_LSEG_SR ||
1504                     nilfs_sc_cstage_get(sci) < NILFS_ST_CPFILE)
1505                         break;
1506 
1507                 nilfs_clear_logs(&sci->sc_segbufs);
1508 
1509                 if (sci->sc_stage.flags & NILFS_CF_SUFREED) {
1510                         err = nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1511                                                         sci->sc_freesegs,
1512                                                         sci->sc_nfreesegs,
1513                                                         NULL);
1514                         WARN_ON(err); /* do not happen */
1515                         sci->sc_stage.flags &= ~NILFS_CF_SUFREED;
1516                 }
1517 
1518                 err = nilfs_segctor_extend_segments(sci, nilfs, nadd);
1519                 if (unlikely(err))
1520                         return err;
1521 
1522                 nadd = min_t(int, nadd << 1, SC_MAX_SEGDELTA);
1523                 sci->sc_stage = prev_stage;
1524         }
1525         nilfs_segctor_truncate_segments(sci, sci->sc_curseg, nilfs->ns_sufile);
1526         return 0;
1527 
1528  failed:
1529         return err;
1530 }
1531 
1532 static void nilfs_list_replace_buffer(struct buffer_head *old_bh,
1533                                       struct buffer_head *new_bh)
1534 {
1535         BUG_ON(!list_empty(&new_bh->b_assoc_buffers));
1536 
1537         list_replace_init(&old_bh->b_assoc_buffers, &new_bh->b_assoc_buffers);
1538         /* The caller must release old_bh */
1539 }
1540 
1541 static int
1542 nilfs_segctor_update_payload_blocknr(struct nilfs_sc_info *sci,
1543                                      struct nilfs_segment_buffer *segbuf,
1544                                      int mode)
1545 {
1546         struct inode *inode = NULL;
1547         sector_t blocknr;
1548         unsigned long nfinfo = segbuf->sb_sum.nfinfo;
1549         unsigned long nblocks = 0, ndatablk = 0;
1550         const struct nilfs_sc_operations *sc_op = NULL;
1551         struct nilfs_segsum_pointer ssp;
1552         struct nilfs_finfo *finfo = NULL;
1553         union nilfs_binfo binfo;
1554         struct buffer_head *bh, *bh_org;
1555         ino_t ino = 0;
1556         int err = 0;
1557 
1558         if (!nfinfo)
1559                 goto out;
1560 
1561         blocknr = segbuf->sb_pseg_start + segbuf->sb_sum.nsumblk;
1562         ssp.bh = NILFS_SEGBUF_FIRST_BH(&segbuf->sb_segsum_buffers);
1563         ssp.offset = sizeof(struct nilfs_segment_summary);
1564 
1565         list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
1566                 if (bh == segbuf->sb_super_root)
1567                         break;
1568                 if (!finfo) {
1569                         finfo = nilfs_segctor_map_segsum_entry(
1570                                 sci, &ssp, sizeof(*finfo));
1571                         ino = le64_to_cpu(finfo->fi_ino);
1572                         nblocks = le32_to_cpu(finfo->fi_nblocks);
1573                         ndatablk = le32_to_cpu(finfo->fi_ndatablk);
1574 
1575                         inode = bh->b_page->mapping->host;
1576 
1577                         if (mode == SC_LSEG_DSYNC)
1578                                 sc_op = &nilfs_sc_dsync_ops;
1579                         else if (ino == NILFS_DAT_INO)
1580                                 sc_op = &nilfs_sc_dat_ops;
1581                         else /* file blocks */
1582                                 sc_op = &nilfs_sc_file_ops;
1583                 }
1584                 bh_org = bh;
1585                 get_bh(bh_org);
1586                 err = nilfs_bmap_assign(NILFS_I(inode)->i_bmap, &bh, blocknr,
1587                                         &binfo);
1588                 if (bh != bh_org)
1589                         nilfs_list_replace_buffer(bh_org, bh);
1590                 brelse(bh_org);
1591                 if (unlikely(err))
1592                         goto failed_bmap;
1593 
1594                 if (ndatablk > 0)
1595                         sc_op->write_data_binfo(sci, &ssp, &binfo);
1596                 else
1597                         sc_op->write_node_binfo(sci, &ssp, &binfo);
1598 
1599                 blocknr++;
1600                 if (--nblocks == 0) {
1601                         finfo = NULL;
1602                         if (--nfinfo == 0)
1603                                 break;
1604                 } else if (ndatablk > 0)
1605                         ndatablk--;
1606         }
1607  out:
1608         return 0;
1609 
1610  failed_bmap:
1611         return err;
1612 }
1613 
1614 static int nilfs_segctor_assign(struct nilfs_sc_info *sci, int mode)
1615 {
1616         struct nilfs_segment_buffer *segbuf;
1617         int err;
1618 
1619         list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1620                 err = nilfs_segctor_update_payload_blocknr(sci, segbuf, mode);
1621                 if (unlikely(err))
1622                         return err;
1623                 nilfs_segbuf_fill_in_segsum(segbuf);
1624         }
1625         return 0;
1626 }
1627 
1628 static void nilfs_begin_page_io(struct page *page)
1629 {
1630         if (!page || PageWriteback(page))
1631                 /*
1632                  * For split b-tree node pages, this function may be called
1633                  * twice.  We ignore the 2nd or later calls by this check.
1634                  */
1635                 return;
1636 
1637         lock_page(page);
1638         clear_page_dirty_for_io(page);
1639         set_page_writeback(page);
1640         unlock_page(page);
1641 }
1642 
1643 static void nilfs_segctor_prepare_write(struct nilfs_sc_info *sci)
1644 {
1645         struct nilfs_segment_buffer *segbuf;
1646         struct page *bd_page = NULL, *fs_page = NULL;
1647 
1648         list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1649                 struct buffer_head *bh;
1650 
1651                 list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1652                                     b_assoc_buffers) {
1653                         if (bh->b_page != bd_page) {
1654                                 if (bd_page) {
1655                                         lock_page(bd_page);
1656                                         clear_page_dirty_for_io(bd_page);
1657                                         set_page_writeback(bd_page);
1658                                         unlock_page(bd_page);
1659                                 }
1660                                 bd_page = bh->b_page;
1661                         }
1662                 }
1663 
1664                 list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1665                                     b_assoc_buffers) {
1666                         set_buffer_async_write(bh);
1667                         if (bh == segbuf->sb_super_root) {
1668                                 if (bh->b_page != bd_page) {
1669                                         lock_page(bd_page);
1670                                         clear_page_dirty_for_io(bd_page);
1671                                         set_page_writeback(bd_page);
1672                                         unlock_page(bd_page);
1673                                         bd_page = bh->b_page;
1674                                 }
1675                                 break;
1676                         }
1677                         if (bh->b_page != fs_page) {
1678                                 nilfs_begin_page_io(fs_page);
1679                                 fs_page = bh->b_page;
1680                         }
1681                 }
1682         }
1683         if (bd_page) {
1684                 lock_page(bd_page);
1685                 clear_page_dirty_for_io(bd_page);
1686                 set_page_writeback(bd_page);
1687                 unlock_page(bd_page);
1688         }
1689         nilfs_begin_page_io(fs_page);
1690 }
1691 
1692 static int nilfs_segctor_write(struct nilfs_sc_info *sci,
1693                                struct the_nilfs *nilfs)
1694 {
1695         int ret;
1696 
1697         ret = nilfs_write_logs(&sci->sc_segbufs, nilfs);
1698         list_splice_tail_init(&sci->sc_segbufs, &sci->sc_write_logs);
1699         return ret;
1700 }
1701 
1702 static void nilfs_end_page_io(struct page *page, int err)
1703 {
1704         if (!page)
1705                 return;
1706 
1707         if (buffer_nilfs_node(page_buffers(page)) && !PageWriteback(page)) {
1708                 /*
1709                  * For b-tree node pages, this function may be called twice
1710                  * or more because they might be split in a segment.
1711                  */
1712                 if (PageDirty(page)) {
1713                         /*
1714                          * For pages holding split b-tree node buffers, dirty
1715                          * flag on the buffers may be cleared discretely.
1716                          * In that case, the page is once redirtied for
1717                          * remaining buffers, and it must be cancelled if
1718                          * all the buffers get cleaned later.
1719                          */
1720                         lock_page(page);
1721                         if (nilfs_page_buffers_clean(page))
1722                                 __nilfs_clear_page_dirty(page);
1723                         unlock_page(page);
1724                 }
1725                 return;
1726         }
1727 
1728         if (!err) {
1729                 if (!nilfs_page_buffers_clean(page))
1730                         __set_page_dirty_nobuffers(page);
1731                 ClearPageError(page);
1732         } else {
1733                 __set_page_dirty_nobuffers(page);
1734                 SetPageError(page);
1735         }
1736 
1737         end_page_writeback(page);
1738 }
1739 
1740 static void nilfs_abort_logs(struct list_head *logs, int err)
1741 {
1742         struct nilfs_segment_buffer *segbuf;
1743         struct page *bd_page = NULL, *fs_page = NULL;
1744         struct buffer_head *bh;
1745 
1746         if (list_empty(logs))
1747                 return;
1748 
1749         list_for_each_entry(segbuf, logs, sb_list) {
1750                 list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1751                                     b_assoc_buffers) {
1752                         if (bh->b_page != bd_page) {
1753                                 if (bd_page)
1754                                         end_page_writeback(bd_page);
1755                                 bd_page = bh->b_page;
1756                         }
1757                 }
1758 
1759                 list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1760                                     b_assoc_buffers) {
1761                         clear_buffer_async_write(bh);
1762                         if (bh == segbuf->sb_super_root) {
1763                                 if (bh->b_page != bd_page) {
1764                                         end_page_writeback(bd_page);
1765                                         bd_page = bh->b_page;
1766                                 }
1767                                 break;
1768                         }
1769                         if (bh->b_page != fs_page) {
1770                                 nilfs_end_page_io(fs_page, err);
1771                                 fs_page = bh->b_page;
1772                         }
1773                 }
1774         }
1775         if (bd_page)
1776                 end_page_writeback(bd_page);
1777 
1778         nilfs_end_page_io(fs_page, err);
1779 }
1780 
1781 static void nilfs_segctor_abort_construction(struct nilfs_sc_info *sci,
1782                                              struct the_nilfs *nilfs, int err)
1783 {
1784         LIST_HEAD(logs);
1785         int ret;
1786 
1787         list_splice_tail_init(&sci->sc_write_logs, &logs);
1788         ret = nilfs_wait_on_logs(&logs);
1789         nilfs_abort_logs(&logs, ret ? : err);
1790 
1791         list_splice_tail_init(&sci->sc_segbufs, &logs);
1792         nilfs_cancel_segusage(&logs, nilfs->ns_sufile);
1793         nilfs_free_incomplete_logs(&logs, nilfs);
1794 
1795         if (sci->sc_stage.flags & NILFS_CF_SUFREED) {
1796                 ret = nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1797                                                 sci->sc_freesegs,
1798                                                 sci->sc_nfreesegs,
1799                                                 NULL);
1800                 WARN_ON(ret); /* do not happen */
1801         }
1802 
1803         nilfs_destroy_logs(&logs);
1804 }
1805 
1806 static void nilfs_set_next_segment(struct the_nilfs *nilfs,
1807                                    struct nilfs_segment_buffer *segbuf)
1808 {
1809         nilfs->ns_segnum = segbuf->sb_segnum;
1810         nilfs->ns_nextnum = segbuf->sb_nextnum;
1811         nilfs->ns_pseg_offset = segbuf->sb_pseg_start - segbuf->sb_fseg_start
1812                 + segbuf->sb_sum.nblocks;
1813         nilfs->ns_seg_seq = segbuf->sb_sum.seg_seq;
1814         nilfs->ns_ctime = segbuf->sb_sum.ctime;
1815 }
1816 
1817 static void nilfs_segctor_complete_write(struct nilfs_sc_info *sci)
1818 {
1819         struct nilfs_segment_buffer *segbuf;
1820         struct page *bd_page = NULL, *fs_page = NULL;
1821         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
1822         int update_sr = false;
1823 
1824         list_for_each_entry(segbuf, &sci->sc_write_logs, sb_list) {
1825                 struct buffer_head *bh;
1826 
1827                 list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1828                                     b_assoc_buffers) {
1829                         set_buffer_uptodate(bh);
1830                         clear_buffer_dirty(bh);
1831                         if (bh->b_page != bd_page) {
1832                                 if (bd_page)
1833                                         end_page_writeback(bd_page);
1834                                 bd_page = bh->b_page;
1835                         }
1836                 }
1837                 /*
1838                  * We assume that the buffers which belong to the same page
1839                  * continue over the buffer list.
1840                  * Under this assumption, the last BHs of pages is
1841                  * identifiable by the discontinuity of bh->b_page
1842                  * (page != fs_page).
1843                  *
1844                  * For B-tree node blocks, however, this assumption is not
1845                  * guaranteed.  The cleanup code of B-tree node pages needs
1846                  * special care.
1847                  */
1848                 list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1849                                     b_assoc_buffers) {
1850                         const unsigned long set_bits = BIT(BH_Uptodate);
1851                         const unsigned long clear_bits =
1852                                 (BIT(BH_Dirty) | BIT(BH_Async_Write) |
1853                                  BIT(BH_Delay) | BIT(BH_NILFS_Volatile) |
1854                                  BIT(BH_NILFS_Redirected));
1855 
1856                         set_mask_bits(&bh->b_state, clear_bits, set_bits);
1857                         if (bh == segbuf->sb_super_root) {
1858                                 if (bh->b_page != bd_page) {
1859                                         end_page_writeback(bd_page);
1860                                         bd_page = bh->b_page;
1861                                 }
1862                                 update_sr = true;
1863                                 break;
1864                         }
1865                         if (bh->b_page != fs_page) {
1866                                 nilfs_end_page_io(fs_page, 0);
1867                                 fs_page = bh->b_page;
1868                         }
1869                 }
1870 
1871                 if (!nilfs_segbuf_simplex(segbuf)) {
1872                         if (segbuf->sb_sum.flags & NILFS_SS_LOGBGN) {
1873                                 set_bit(NILFS_SC_UNCLOSED, &sci->sc_flags);
1874                                 sci->sc_lseg_stime = jiffies;
1875                         }
1876                         if (segbuf->sb_sum.flags & NILFS_SS_LOGEND)
1877                                 clear_bit(NILFS_SC_UNCLOSED, &sci->sc_flags);
1878                 }
1879         }
1880         /*
1881          * Since pages may continue over multiple segment buffers,
1882          * end of the last page must be checked outside of the loop.
1883          */
1884         if (bd_page)
1885                 end_page_writeback(bd_page);
1886 
1887         nilfs_end_page_io(fs_page, 0);
1888 
1889         nilfs_drop_collected_inodes(&sci->sc_dirty_files);
1890 
1891         if (nilfs_doing_gc())
1892                 nilfs_drop_collected_inodes(&sci->sc_gc_inodes);
1893         else
1894                 nilfs->ns_nongc_ctime = sci->sc_seg_ctime;
1895 
1896         sci->sc_nblk_inc += sci->sc_nblk_this_inc;
1897 
1898         segbuf = NILFS_LAST_SEGBUF(&sci->sc_write_logs);
1899         nilfs_set_next_segment(nilfs, segbuf);
1900 
1901         if (update_sr) {
1902                 nilfs->ns_flushed_device = 0;
1903                 nilfs_set_last_segment(nilfs, segbuf->sb_pseg_start,
1904                                        segbuf->sb_sum.seg_seq, nilfs->ns_cno++);
1905 
1906                 clear_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
1907                 clear_bit(NILFS_SC_DIRTY, &sci->sc_flags);
1908                 set_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags);
1909                 nilfs_segctor_clear_metadata_dirty(sci);
1910         } else
1911                 clear_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags);
1912 }
1913 
1914 static int nilfs_segctor_wait(struct nilfs_sc_info *sci)
1915 {
1916         int ret;
1917 
1918         ret = nilfs_wait_on_logs(&sci->sc_write_logs);
1919         if (!ret) {
1920                 nilfs_segctor_complete_write(sci);
1921                 nilfs_destroy_logs(&sci->sc_write_logs);
1922         }
1923         return ret;
1924 }
1925 
1926 static int nilfs_segctor_collect_dirty_files(struct nilfs_sc_info *sci,
1927                                              struct the_nilfs *nilfs)
1928 {
1929         struct nilfs_inode_info *ii, *n;
1930         struct inode *ifile = sci->sc_root->ifile;
1931 
1932         spin_lock(&nilfs->ns_inode_lock);
1933  retry:
1934         list_for_each_entry_safe(ii, n, &nilfs->ns_dirty_files, i_dirty) {
1935                 if (!ii->i_bh) {
1936                         struct buffer_head *ibh;
1937                         int err;
1938 
1939                         spin_unlock(&nilfs->ns_inode_lock);
1940                         err = nilfs_ifile_get_inode_block(
1941                                 ifile, ii->vfs_inode.i_ino, &ibh);
1942                         if (unlikely(err)) {
1943                                 nilfs_msg(sci->sc_super, KERN_WARNING,
1944                                           "log writer: error %d getting inode block (ino=%lu)",
1945                                           err, ii->vfs_inode.i_ino);
1946                                 return err;
1947                         }
1948                         spin_lock(&nilfs->ns_inode_lock);
1949                         if (likely(!ii->i_bh))
1950                                 ii->i_bh = ibh;
1951                         else
1952                                 brelse(ibh);
1953                         goto retry;
1954                 }
1955 
1956                 // Always redirty the buffer to avoid race condition
1957                 mark_buffer_dirty(ii->i_bh);
1958                 nilfs_mdt_mark_dirty(ifile);
1959 
1960                 clear_bit(NILFS_I_QUEUED, &ii->i_state);
1961                 set_bit(NILFS_I_BUSY, &ii->i_state);
1962                 list_move_tail(&ii->i_dirty, &sci->sc_dirty_files);
1963         }
1964         spin_unlock(&nilfs->ns_inode_lock);
1965 
1966         return 0;
1967 }
1968 
1969 static void nilfs_segctor_drop_written_files(struct nilfs_sc_info *sci,
1970                                              struct the_nilfs *nilfs)
1971 {
1972         struct nilfs_inode_info *ii, *n;
1973         int during_mount = !(sci->sc_super->s_flags & SB_ACTIVE);
1974         int defer_iput = false;
1975 
1976         spin_lock(&nilfs->ns_inode_lock);
1977         list_for_each_entry_safe(ii, n, &sci->sc_dirty_files, i_dirty) {
1978                 if (!test_and_clear_bit(NILFS_I_UPDATED, &ii->i_state) ||
1979                     test_bit(NILFS_I_DIRTY, &ii->i_state))
1980                         continue;
1981 
1982                 clear_bit(NILFS_I_BUSY, &ii->i_state);
1983                 brelse(ii->i_bh);
1984                 ii->i_bh = NULL;
1985                 list_del_init(&ii->i_dirty);
1986                 if (!ii->vfs_inode.i_nlink || during_mount) {
1987                         /*
1988                          * Defer calling iput() to avoid deadlocks if
1989                          * i_nlink == 0 or mount is not yet finished.
1990                          */
1991                         list_add_tail(&ii->i_dirty, &sci->sc_iput_queue);
1992                         defer_iput = true;
1993                 } else {
1994                         spin_unlock(&nilfs->ns_inode_lock);
1995                         iput(&ii->vfs_inode);
1996                         spin_lock(&nilfs->ns_inode_lock);
1997                 }
1998         }
1999         spin_unlock(&nilfs->ns_inode_lock);
2000 
2001         if (defer_iput)
2002                 schedule_work(&sci->sc_iput_work);
2003 }
2004 
2005 /*
2006  * Main procedure of segment constructor
2007  */
2008 static int nilfs_segctor_do_construct(struct nilfs_sc_info *sci, int mode)
2009 {
2010         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2011         int err;
2012 
2013         nilfs_sc_cstage_set(sci, NILFS_ST_INIT);
2014         sci->sc_cno = nilfs->ns_cno;
2015 
2016         err = nilfs_segctor_collect_dirty_files(sci, nilfs);
2017         if (unlikely(err))
2018                 goto out;
2019 
2020         if (nilfs_test_metadata_dirty(nilfs, sci->sc_root))
2021                 set_bit(NILFS_SC_DIRTY, &sci->sc_flags);
2022 
2023         if (nilfs_segctor_clean(sci))
2024                 goto out;
2025 
2026         do {
2027                 sci->sc_stage.flags &= ~NILFS_CF_HISTORY_MASK;
2028 
2029                 err = nilfs_segctor_begin_construction(sci, nilfs);
2030                 if (unlikely(err))
2031                         goto out;
2032 
2033                 /* Update time stamp */
2034                 sci->sc_seg_ctime = ktime_get_real_seconds();
2035 
2036                 err = nilfs_segctor_collect(sci, nilfs, mode);
2037                 if (unlikely(err))
2038                         goto failed;
2039 
2040                 /* Avoid empty segment */
2041                 if (nilfs_sc_cstage_get(sci) == NILFS_ST_DONE &&
2042                     nilfs_segbuf_empty(sci->sc_curseg)) {
2043                         nilfs_segctor_abort_construction(sci, nilfs, 1);
2044                         goto out;
2045                 }
2046 
2047                 err = nilfs_segctor_assign(sci, mode);
2048                 if (unlikely(err))
2049                         goto failed;
2050 
2051                 if (sci->sc_stage.flags & NILFS_CF_IFILE_STARTED)
2052                         nilfs_segctor_fill_in_file_bmap(sci);
2053 
2054                 if (mode == SC_LSEG_SR &&
2055                     nilfs_sc_cstage_get(sci) >= NILFS_ST_CPFILE) {
2056                         err = nilfs_segctor_fill_in_checkpoint(sci);
2057                         if (unlikely(err))
2058                                 goto failed_to_write;
2059 
2060                         nilfs_segctor_fill_in_super_root(sci, nilfs);
2061                 }
2062                 nilfs_segctor_update_segusage(sci, nilfs->ns_sufile);
2063 
2064                 /* Write partial segments */
2065                 nilfs_segctor_prepare_write(sci);
2066 
2067                 nilfs_add_checksums_on_logs(&sci->sc_segbufs,
2068                                             nilfs->ns_crc_seed);
2069 
2070                 err = nilfs_segctor_write(sci, nilfs);
2071                 if (unlikely(err))
2072                         goto failed_to_write;
2073 
2074                 if (nilfs_sc_cstage_get(sci) == NILFS_ST_DONE ||
2075                     nilfs->ns_blocksize_bits != PAGE_SHIFT) {
2076                         /*
2077                          * At this point, we avoid double buffering
2078                          * for blocksize < pagesize because page dirty
2079                          * flag is turned off during write and dirty
2080                          * buffers are not properly collected for
2081                          * pages crossing over segments.
2082                          */
2083                         err = nilfs_segctor_wait(sci);
2084                         if (err)
2085                                 goto failed_to_write;
2086                 }
2087         } while (nilfs_sc_cstage_get(sci) != NILFS_ST_DONE);
2088 
2089  out:
2090         nilfs_segctor_drop_written_files(sci, nilfs);
2091         return err;
2092 
2093  failed_to_write:
2094         if (sci->sc_stage.flags & NILFS_CF_IFILE_STARTED)
2095                 nilfs_redirty_inodes(&sci->sc_dirty_files);
2096 
2097  failed:
2098         if (nilfs_doing_gc())
2099                 nilfs_redirty_inodes(&sci->sc_gc_inodes);
2100         nilfs_segctor_abort_construction(sci, nilfs, err);
2101         goto out;
2102 }
2103 
2104 /**
2105  * nilfs_segctor_start_timer - set timer of background write
2106  * @sci: nilfs_sc_info
2107  *
2108  * If the timer has already been set, it ignores the new request.
2109  * This function MUST be called within a section locking the segment
2110  * semaphore.
2111  */
2112 static void nilfs_segctor_start_timer(struct nilfs_sc_info *sci)
2113 {
2114         spin_lock(&sci->sc_state_lock);
2115         if (!(sci->sc_state & NILFS_SEGCTOR_COMMIT)) {
2116                 sci->sc_timer.expires = jiffies + sci->sc_interval;
2117                 add_timer(&sci->sc_timer);
2118                 sci->sc_state |= NILFS_SEGCTOR_COMMIT;
2119         }
2120         spin_unlock(&sci->sc_state_lock);
2121 }
2122 
2123 static void nilfs_segctor_do_flush(struct nilfs_sc_info *sci, int bn)
2124 {
2125         spin_lock(&sci->sc_state_lock);
2126         if (!(sci->sc_flush_request & BIT(bn))) {
2127                 unsigned long prev_req = sci->sc_flush_request;
2128 
2129                 sci->sc_flush_request |= BIT(bn);
2130                 if (!prev_req)
2131                         wake_up(&sci->sc_wait_daemon);
2132         }
2133         spin_unlock(&sci->sc_state_lock);
2134 }
2135 
2136 /**
2137  * nilfs_flush_segment - trigger a segment construction for resource control
2138  * @sb: super block
2139  * @ino: inode number of the file to be flushed out.
2140  */
2141 void nilfs_flush_segment(struct super_block *sb, ino_t ino)
2142 {
2143         struct the_nilfs *nilfs = sb->s_fs_info;
2144         struct nilfs_sc_info *sci = nilfs->ns_writer;
2145 
2146         if (!sci || nilfs_doing_construction())
2147                 return;
2148         nilfs_segctor_do_flush(sci, NILFS_MDT_INODE(sb, ino) ? ino : 0);
2149                                         /* assign bit 0 to data files */
2150 }
2151 
2152 struct nilfs_segctor_wait_request {
2153         wait_queue_entry_t      wq;
2154         __u32           seq;
2155         int             err;
2156         atomic_t        done;
2157 };
2158 
2159 static int nilfs_segctor_sync(struct nilfs_sc_info *sci)
2160 {
2161         struct nilfs_segctor_wait_request wait_req;
2162         int err = 0;
2163 
2164         spin_lock(&sci->sc_state_lock);
2165         init_wait(&wait_req.wq);
2166         wait_req.err = 0;
2167         atomic_set(&wait_req.done, 0);
2168         wait_req.seq = ++sci->sc_seq_request;
2169         spin_unlock(&sci->sc_state_lock);
2170 
2171         init_waitqueue_entry(&wait_req.wq, current);
2172         add_wait_queue(&sci->sc_wait_request, &wait_req.wq);
2173         set_current_state(TASK_INTERRUPTIBLE);
2174         wake_up(&sci->sc_wait_daemon);
2175 
2176         for (;;) {
2177                 if (atomic_read(&wait_req.done)) {
2178                         err = wait_req.err;
2179                         break;
2180                 }
2181                 if (!signal_pending(current)) {
2182                         schedule();
2183                         continue;
2184                 }
2185                 err = -ERESTARTSYS;
2186                 break;
2187         }
2188         finish_wait(&sci->sc_wait_request, &wait_req.wq);
2189         return err;
2190 }
2191 
2192 static void nilfs_segctor_wakeup(struct nilfs_sc_info *sci, int err)
2193 {
2194         struct nilfs_segctor_wait_request *wrq, *n;
2195         unsigned long flags;
2196 
2197         spin_lock_irqsave(&sci->sc_wait_request.lock, flags);
2198         list_for_each_entry_safe(wrq, n, &sci->sc_wait_request.head, wq.entry) {
2199                 if (!atomic_read(&wrq->done) &&
2200                     nilfs_cnt32_ge(sci->sc_seq_done, wrq->seq)) {
2201                         wrq->err = err;
2202                         atomic_set(&wrq->done, 1);
2203                 }
2204                 if (atomic_read(&wrq->done)) {
2205                         wrq->wq.func(&wrq->wq,
2206                                      TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
2207                                      0, NULL);
2208                 }
2209         }
2210         spin_unlock_irqrestore(&sci->sc_wait_request.lock, flags);
2211 }
2212 
2213 /**
2214  * nilfs_construct_segment - construct a logical segment
2215  * @sb: super block
2216  *
2217  * Return Value: On success, 0 is retured. On errors, one of the following
2218  * negative error code is returned.
2219  *
2220  * %-EROFS - Read only filesystem.
2221  *
2222  * %-EIO - I/O error
2223  *
2224  * %-ENOSPC - No space left on device (only in a panic state).
2225  *
2226  * %-ERESTARTSYS - Interrupted.
2227  *
2228  * %-ENOMEM - Insufficient memory available.
2229  */
2230 int nilfs_construct_segment(struct super_block *sb)
2231 {
2232         struct the_nilfs *nilfs = sb->s_fs_info;
2233         struct nilfs_sc_info *sci = nilfs->ns_writer;
2234         struct nilfs_transaction_info *ti;
2235         int err;
2236 
2237         if (!sci)
2238                 return -EROFS;
2239 
2240         /* A call inside transactions causes a deadlock. */
2241         BUG_ON((ti = current->journal_info) && ti->ti_magic == NILFS_TI_MAGIC);
2242 
2243         err = nilfs_segctor_sync(sci);
2244         return err;
2245 }
2246 
2247 /**
2248  * nilfs_construct_dsync_segment - construct a data-only logical segment
2249  * @sb: super block
2250  * @inode: inode whose data blocks should be written out
2251  * @start: start byte offset
2252  * @end: end byte offset (inclusive)
2253  *
2254  * Return Value: On success, 0 is retured. On errors, one of the following
2255  * negative error code is returned.
2256  *
2257  * %-EROFS - Read only filesystem.
2258  *
2259  * %-EIO - I/O error
2260  *
2261  * %-ENOSPC - No space left on device (only in a panic state).
2262  *
2263  * %-ERESTARTSYS - Interrupted.
2264  *
2265  * %-ENOMEM - Insufficient memory available.
2266  */
2267 int nilfs_construct_dsync_segment(struct super_block *sb, struct inode *inode,
2268                                   loff_t start, loff_t end)
2269 {
2270         struct the_nilfs *nilfs = sb->s_fs_info;
2271         struct nilfs_sc_info *sci = nilfs->ns_writer;
2272         struct nilfs_inode_info *ii;
2273         struct nilfs_transaction_info ti;
2274         int err = 0;
2275 
2276         if (!sci)
2277                 return -EROFS;
2278 
2279         nilfs_transaction_lock(sb, &ti, 0);
2280 
2281         ii = NILFS_I(inode);
2282         if (test_bit(NILFS_I_INODE_SYNC, &ii->i_state) ||
2283             nilfs_test_opt(nilfs, STRICT_ORDER) ||
2284             test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags) ||
2285             nilfs_discontinued(nilfs)) {
2286                 nilfs_transaction_unlock(sb);
2287                 err = nilfs_segctor_sync(sci);
2288                 return err;
2289         }
2290 
2291         spin_lock(&nilfs->ns_inode_lock);
2292         if (!test_bit(NILFS_I_QUEUED, &ii->i_state) &&
2293             !test_bit(NILFS_I_BUSY, &ii->i_state)) {
2294                 spin_unlock(&nilfs->ns_inode_lock);
2295                 nilfs_transaction_unlock(sb);
2296                 return 0;
2297         }
2298         spin_unlock(&nilfs->ns_inode_lock);
2299         sci->sc_dsync_inode = ii;
2300         sci->sc_dsync_start = start;
2301         sci->sc_dsync_end = end;
2302 
2303         err = nilfs_segctor_do_construct(sci, SC_LSEG_DSYNC);
2304         if (!err)
2305                 nilfs->ns_flushed_device = 0;
2306 
2307         nilfs_transaction_unlock(sb);
2308         return err;
2309 }
2310 
2311 #define FLUSH_FILE_BIT  (0x1) /* data file only */
2312 #define FLUSH_DAT_BIT   BIT(NILFS_DAT_INO) /* DAT only */
2313 
2314 /**
2315  * nilfs_segctor_accept - record accepted sequence count of log-write requests
2316  * @sci: segment constructor object
2317  */
2318 static void nilfs_segctor_accept(struct nilfs_sc_info *sci)
2319 {
2320         spin_lock(&sci->sc_state_lock);
2321         sci->sc_seq_accepted = sci->sc_seq_request;
2322         spin_unlock(&sci->sc_state_lock);
2323         del_timer_sync(&sci->sc_timer);
2324 }
2325 
2326 /**
2327  * nilfs_segctor_notify - notify the result of request to caller threads
2328  * @sci: segment constructor object
2329  * @mode: mode of log forming
2330  * @err: error code to be notified
2331  */
2332 static void nilfs_segctor_notify(struct nilfs_sc_info *sci, int mode, int err)
2333 {
2334         /* Clear requests (even when the construction failed) */
2335         spin_lock(&sci->sc_state_lock);
2336 
2337         if (mode == SC_LSEG_SR) {
2338                 sci->sc_state &= ~NILFS_SEGCTOR_COMMIT;
2339                 sci->sc_seq_done = sci->sc_seq_accepted;
2340                 nilfs_segctor_wakeup(sci, err);
2341                 sci->sc_flush_request = 0;
2342         } else {
2343                 if (mode == SC_FLUSH_FILE)
2344                         sci->sc_flush_request &= ~FLUSH_FILE_BIT;
2345                 else if (mode == SC_FLUSH_DAT)
2346                         sci->sc_flush_request &= ~FLUSH_DAT_BIT;
2347 
2348                 /* re-enable timer if checkpoint creation was not done */
2349                 if ((sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
2350                     time_before(jiffies, sci->sc_timer.expires))
2351                         add_timer(&sci->sc_timer);
2352         }
2353         spin_unlock(&sci->sc_state_lock);
2354 }
2355 
2356 /**
2357  * nilfs_segctor_construct - form logs and write them to disk
2358  * @sci: segment constructor object
2359  * @mode: mode of log forming
2360  */
2361 static int nilfs_segctor_construct(struct nilfs_sc_info *sci, int mode)
2362 {
2363         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2364         struct nilfs_super_block **sbp;
2365         int err = 0;
2366 
2367         nilfs_segctor_accept(sci);
2368 
2369         if (nilfs_discontinued(nilfs))
2370                 mode = SC_LSEG_SR;
2371         if (!nilfs_segctor_confirm(sci))
2372                 err = nilfs_segctor_do_construct(sci, mode);
2373 
2374         if (likely(!err)) {
2375                 if (mode != SC_FLUSH_DAT)
2376                         atomic_set(&nilfs->ns_ndirtyblks, 0);
2377                 if (test_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags) &&
2378                     nilfs_discontinued(nilfs)) {
2379                         down_write(&nilfs->ns_sem);
2380                         err = -EIO;
2381                         sbp = nilfs_prepare_super(sci->sc_super,
2382                                                   nilfs_sb_will_flip(nilfs));
2383                         if (likely(sbp)) {
2384                                 nilfs_set_log_cursor(sbp[0], nilfs);
2385                                 err = nilfs_commit_super(sci->sc_super,
2386                                                          NILFS_SB_COMMIT);
2387                         }
2388                         up_write(&nilfs->ns_sem);
2389                 }
2390         }
2391 
2392         nilfs_segctor_notify(sci, mode, err);
2393         return err;
2394 }
2395 
2396 static void nilfs_construction_timeout(struct timer_list *t)
2397 {
2398         struct nilfs_sc_info *sci = from_timer(sci, t, sc_timer);
2399 
2400         wake_up_process(sci->sc_timer_task);
2401 }
2402 
2403 static void
2404 nilfs_remove_written_gcinodes(struct the_nilfs *nilfs, struct list_head *head)
2405 {
2406         struct nilfs_inode_info *ii, *n;
2407 
2408         list_for_each_entry_safe(ii, n, head, i_dirty) {
2409                 if (!test_bit(NILFS_I_UPDATED, &ii->i_state))
2410                         continue;
2411                 list_del_init(&ii->i_dirty);
2412                 truncate_inode_pages(&ii->vfs_inode.i_data, 0);
2413                 nilfs_btnode_cache_clear(&ii->i_btnode_cache);
2414                 iput(&ii->vfs_inode);
2415         }
2416 }
2417 
2418 int nilfs_clean_segments(struct super_block *sb, struct nilfs_argv *argv,
2419                          void **kbufs)
2420 {
2421         struct the_nilfs *nilfs = sb->s_fs_info;
2422         struct nilfs_sc_info *sci = nilfs->ns_writer;
2423         struct nilfs_transaction_info ti;
2424         int err;
2425 
2426         if (unlikely(!sci))
2427                 return -EROFS;
2428 
2429         nilfs_transaction_lock(sb, &ti, 1);
2430 
2431         err = nilfs_mdt_save_to_shadow_map(nilfs->ns_dat);
2432         if (unlikely(err))
2433                 goto out_unlock;
2434 
2435         err = nilfs_ioctl_prepare_clean_segments(nilfs, argv, kbufs);
2436         if (unlikely(err)) {
2437                 nilfs_mdt_restore_from_shadow_map(nilfs->ns_dat);
2438                 goto out_unlock;
2439         }
2440 
2441         sci->sc_freesegs = kbufs[4];
2442         sci->sc_nfreesegs = argv[4].v_nmembs;
2443         list_splice_tail_init(&nilfs->ns_gc_inodes, &sci->sc_gc_inodes);
2444 
2445         for (;;) {
2446                 err = nilfs_segctor_construct(sci, SC_LSEG_SR);
2447                 nilfs_remove_written_gcinodes(nilfs, &sci->sc_gc_inodes);
2448 
2449                 if (likely(!err))
2450                         break;
2451 
2452                 nilfs_msg(sb, KERN_WARNING, "error %d cleaning segments", err);
2453                 set_current_state(TASK_INTERRUPTIBLE);
2454                 schedule_timeout(sci->sc_interval);
2455         }
2456         if (nilfs_test_opt(nilfs, DISCARD)) {
2457                 int ret = nilfs_discard_segments(nilfs, sci->sc_freesegs,
2458                                                  sci->sc_nfreesegs);
2459                 if (ret) {
2460                         nilfs_msg(sb, KERN_WARNING,
2461                                   "error %d on discard request, turning discards off for the device",
2462                                   ret);
2463                         nilfs_clear_opt(nilfs, DISCARD);
2464                 }
2465         }
2466 
2467  out_unlock:
2468         sci->sc_freesegs = NULL;
2469         sci->sc_nfreesegs = 0;
2470         nilfs_mdt_clear_shadow_map(nilfs->ns_dat);
2471         nilfs_transaction_unlock(sb);
2472         return err;
2473 }
2474 
2475 static void nilfs_segctor_thread_construct(struct nilfs_sc_info *sci, int mode)
2476 {
2477         struct nilfs_transaction_info ti;
2478 
2479         nilfs_transaction_lock(sci->sc_super, &ti, 0);
2480         nilfs_segctor_construct(sci, mode);
2481 
2482         /*
2483          * Unclosed segment should be retried.  We do this using sc_timer.
2484          * Timeout of sc_timer will invoke complete construction which leads
2485          * to close the current logical segment.
2486          */
2487         if (test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags))
2488                 nilfs_segctor_start_timer(sci);
2489 
2490         nilfs_transaction_unlock(sci->sc_super);
2491 }
2492 
2493 static void nilfs_segctor_do_immediate_flush(struct nilfs_sc_info *sci)
2494 {
2495         int mode = 0;
2496 
2497         spin_lock(&sci->sc_state_lock);
2498         mode = (sci->sc_flush_request & FLUSH_DAT_BIT) ?
2499                 SC_FLUSH_DAT : SC_FLUSH_FILE;
2500         spin_unlock(&sci->sc_state_lock);
2501 
2502         if (mode) {
2503                 nilfs_segctor_do_construct(sci, mode);
2504 
2505                 spin_lock(&sci->sc_state_lock);
2506                 sci->sc_flush_request &= (mode == SC_FLUSH_FILE) ?
2507                         ~FLUSH_FILE_BIT : ~FLUSH_DAT_BIT;
2508                 spin_unlock(&sci->sc_state_lock);
2509         }
2510         clear_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags);
2511 }
2512 
2513 static int nilfs_segctor_flush_mode(struct nilfs_sc_info *sci)
2514 {
2515         if (!test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags) ||
2516             time_before(jiffies, sci->sc_lseg_stime + sci->sc_mjcp_freq)) {
2517                 if (!(sci->sc_flush_request & ~FLUSH_FILE_BIT))
2518                         return SC_FLUSH_FILE;
2519                 else if (!(sci->sc_flush_request & ~FLUSH_DAT_BIT))
2520                         return SC_FLUSH_DAT;
2521         }
2522         return SC_LSEG_SR;
2523 }
2524 
2525 /**
2526  * nilfs_segctor_thread - main loop of the segment constructor thread.
2527  * @arg: pointer to a struct nilfs_sc_info.
2528  *
2529  * nilfs_segctor_thread() initializes a timer and serves as a daemon
2530  * to execute segment constructions.
2531  */
2532 static int nilfs_segctor_thread(void *arg)
2533 {
2534         struct nilfs_sc_info *sci = (struct nilfs_sc_info *)arg;
2535         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2536         int timeout = 0;
2537 
2538         sci->sc_timer_task = current;
2539 
2540         /* start sync. */
2541         sci->sc_task = current;
2542         wake_up(&sci->sc_wait_task); /* for nilfs_segctor_start_thread() */
2543         nilfs_msg(sci->sc_super, KERN_INFO,
2544                   "segctord starting. Construction interval = %lu seconds, CP frequency < %lu seconds",
2545                   sci->sc_interval / HZ, sci->sc_mjcp_freq / HZ);
2546 
2547         spin_lock(&sci->sc_state_lock);
2548  loop:
2549         for (;;) {
2550                 int mode;
2551 
2552                 if (sci->sc_state & NILFS_SEGCTOR_QUIT)
2553                         goto end_thread;
2554 
2555                 if (timeout || sci->sc_seq_request != sci->sc_seq_done)
2556                         mode = SC_LSEG_SR;
2557                 else if (sci->sc_flush_request)
2558                         mode = nilfs_segctor_flush_mode(sci);
2559                 else
2560                         break;
2561 
2562                 spin_unlock(&sci->sc_state_lock);
2563                 nilfs_segctor_thread_construct(sci, mode);
2564                 spin_lock(&sci->sc_state_lock);
2565                 timeout = 0;
2566         }
2567 
2568 
2569         if (freezing(current)) {
2570                 spin_unlock(&sci->sc_state_lock);
2571                 try_to_freeze();
2572                 spin_lock(&sci->sc_state_lock);
2573         } else {
2574                 DEFINE_WAIT(wait);
2575                 int should_sleep = 1;
2576 
2577                 prepare_to_wait(&sci->sc_wait_daemon, &wait,
2578                                 TASK_INTERRUPTIBLE);
2579 
2580                 if (sci->sc_seq_request != sci->sc_seq_done)
2581                         should_sleep = 0;
2582                 else if (sci->sc_flush_request)
2583                         should_sleep = 0;
2584                 else if (sci->sc_state & NILFS_SEGCTOR_COMMIT)
2585                         should_sleep = time_before(jiffies,
2586                                         sci->sc_timer.expires);
2587 
2588                 if (should_sleep) {
2589                         spin_unlock(&sci->sc_state_lock);
2590                         schedule();
2591                         spin_lock(&sci->sc_state_lock);
2592                 }
2593                 finish_wait(&sci->sc_wait_daemon, &wait);
2594                 timeout = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
2595                            time_after_eq(jiffies, sci->sc_timer.expires));
2596 
2597                 if (nilfs_sb_dirty(nilfs) && nilfs_sb_need_update(nilfs))
2598                         set_nilfs_discontinued(nilfs);
2599         }
2600         goto loop;
2601 
2602  end_thread:
2603         spin_unlock(&sci->sc_state_lock);
2604 
2605         /* end sync. */
2606         sci->sc_task = NULL;
2607         wake_up(&sci->sc_wait_task); /* for nilfs_segctor_kill_thread() */
2608         return 0;
2609 }
2610 
2611 static int nilfs_segctor_start_thread(struct nilfs_sc_info *sci)
2612 {
2613         struct task_struct *t;
2614 
2615         t = kthread_run(nilfs_segctor_thread, sci, "segctord");
2616         if (IS_ERR(t)) {
2617                 int err = PTR_ERR(t);
2618 
2619                 nilfs_msg(sci->sc_super, KERN_ERR,
2620                           "error %d creating segctord thread", err);
2621                 return err;
2622         }
2623         wait_event(sci->sc_wait_task, sci->sc_task != NULL);
2624         return 0;
2625 }
2626 
2627 static void nilfs_segctor_kill_thread(struct nilfs_sc_info *sci)
2628         __acquires(&sci->sc_state_lock)
2629         __releases(&sci->sc_state_lock)
2630 {
2631         sci->sc_state |= NILFS_SEGCTOR_QUIT;
2632 
2633         while (sci->sc_task) {
2634                 wake_up(&sci->sc_wait_daemon);
2635                 spin_unlock(&sci->sc_state_lock);
2636                 wait_event(sci->sc_wait_task, sci->sc_task == NULL);
2637                 spin_lock(&sci->sc_state_lock);
2638         }
2639 }
2640 
2641 /*
2642  * Setup & clean-up functions
2643  */
2644 static struct nilfs_sc_info *nilfs_segctor_new(struct super_block *sb,
2645                                                struct nilfs_root *root)
2646 {
2647         struct the_nilfs *nilfs = sb->s_fs_info;
2648         struct nilfs_sc_info *sci;
2649 
2650         sci = kzalloc(sizeof(*sci), GFP_KERNEL);
2651         if (!sci)
2652                 return NULL;
2653 
2654         sci->sc_super = sb;
2655 
2656         nilfs_get_root(root);
2657         sci->sc_root = root;
2658 
2659         init_waitqueue_head(&sci->sc_wait_request);
2660         init_waitqueue_head(&sci->sc_wait_daemon);
2661         init_waitqueue_head(&sci->sc_wait_task);
2662         spin_lock_init(&sci->sc_state_lock);
2663         INIT_LIST_HEAD(&sci->sc_dirty_files);
2664         INIT_LIST_HEAD(&sci->sc_segbufs);
2665         INIT_LIST_HEAD(&sci->sc_write_logs);
2666         INIT_LIST_HEAD(&sci->sc_gc_inodes);
2667         INIT_LIST_HEAD(&sci->sc_iput_queue);
2668         INIT_WORK(&sci->sc_iput_work, nilfs_iput_work_func);
2669         timer_setup(&sci->sc_timer, nilfs_construction_timeout, 0);
2670 
2671         sci->sc_interval = HZ * NILFS_SC_DEFAULT_TIMEOUT;
2672         sci->sc_mjcp_freq = HZ * NILFS_SC_DEFAULT_SR_FREQ;
2673         sci->sc_watermark = NILFS_SC_DEFAULT_WATERMARK;
2674 
2675         if (nilfs->ns_interval)
2676                 sci->sc_interval = HZ * nilfs->ns_interval;
2677         if (nilfs->ns_watermark)
2678                 sci->sc_watermark = nilfs->ns_watermark;
2679         return sci;
2680 }
2681 
2682 static void nilfs_segctor_write_out(struct nilfs_sc_info *sci)
2683 {
2684         int ret, retrycount = NILFS_SC_CLEANUP_RETRY;
2685 
2686         /*
2687          * The segctord thread was stopped and its timer was removed.
2688          * But some tasks remain.
2689          */
2690         do {
2691                 struct nilfs_transaction_info ti;
2692 
2693                 nilfs_transaction_lock(sci->sc_super, &ti, 0);
2694                 ret = nilfs_segctor_construct(sci, SC_LSEG_SR);
2695                 nilfs_transaction_unlock(sci->sc_super);
2696 
2697                 flush_work(&sci->sc_iput_work);
2698 
2699         } while (ret && retrycount-- > 0);
2700 }
2701 
2702 /**
2703  * nilfs_segctor_destroy - destroy the segment constructor.
2704  * @sci: nilfs_sc_info
2705  *
2706  * nilfs_segctor_destroy() kills the segctord thread and frees
2707  * the nilfs_sc_info struct.
2708  * Caller must hold the segment semaphore.
2709  */
2710 static void nilfs_segctor_destroy(struct nilfs_sc_info *sci)
2711 {
2712         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2713         int flag;
2714 
2715         up_write(&nilfs->ns_segctor_sem);
2716 
2717         spin_lock(&sci->sc_state_lock);
2718         nilfs_segctor_kill_thread(sci);
2719         flag = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) || sci->sc_flush_request
2720                 || sci->sc_seq_request != sci->sc_seq_done);
2721         spin_unlock(&sci->sc_state_lock);
2722 
2723         if (flush_work(&sci->sc_iput_work))
2724                 flag = true;
2725 
2726         if (flag || !nilfs_segctor_confirm(sci))
2727                 nilfs_segctor_write_out(sci);
2728 
2729         if (!list_empty(&sci->sc_dirty_files)) {
2730                 nilfs_msg(sci->sc_super, KERN_WARNING,
2731                           "disposed unprocessed dirty file(s) when stopping log writer");
2732                 nilfs_dispose_list(nilfs, &sci->sc_dirty_files, 1);
2733         }
2734 
2735         if (!list_empty(&sci->sc_iput_queue)) {
2736                 nilfs_msg(sci->sc_super, KERN_WARNING,
2737                           "disposed unprocessed inode(s) in iput queue when stopping log writer");
2738                 nilfs_dispose_list(nilfs, &sci->sc_iput_queue, 1);
2739         }
2740 
2741         WARN_ON(!list_empty(&sci->sc_segbufs));
2742         WARN_ON(!list_empty(&sci->sc_write_logs));
2743 
2744         nilfs_put_root(sci->sc_root);
2745 
2746         down_write(&nilfs->ns_segctor_sem);
2747 
2748         del_timer_sync(&sci->sc_timer);
2749         kfree(sci);
2750 }
2751 
2752 /**
2753  * nilfs_attach_log_writer - attach log writer
2754  * @sb: super block instance
2755  * @root: root object of the current filesystem tree
2756  *
2757  * This allocates a log writer object, initializes it, and starts the
2758  * log writer.
2759  *
2760  * Return Value: On success, 0 is returned. On error, one of the following
2761  * negative error code is returned.
2762  *
2763  * %-ENOMEM - Insufficient memory available.
2764  */
2765 int nilfs_attach_log_writer(struct super_block *sb, struct nilfs_root *root)
2766 {
2767         struct the_nilfs *nilfs = sb->s_fs_info;
2768         int err;
2769 
2770         if (nilfs->ns_writer) {
2771                 /*
2772                  * This happens if the filesystem was remounted
2773                  * read/write after nilfs_error degenerated it into a
2774                  * read-only mount.
2775                  */
2776                 nilfs_detach_log_writer(sb);
2777         }
2778 
2779         nilfs->ns_writer = nilfs_segctor_new(sb, root);
2780         if (!nilfs->ns_writer)
2781                 return -ENOMEM;
2782 
2783         err = nilfs_segctor_start_thread(nilfs->ns_writer);
2784         if (err) {
2785                 kfree(nilfs->ns_writer);
2786                 nilfs->ns_writer = NULL;
2787         }
2788         return err;
2789 }
2790 
2791 /**
2792  * nilfs_detach_log_writer - destroy log writer
2793  * @sb: super block instance
2794  *
2795  * This kills log writer daemon, frees the log writer object, and
2796  * destroys list of dirty files.
2797  */
2798 void nilfs_detach_log_writer(struct super_block *sb)
2799 {
2800         struct the_nilfs *nilfs = sb->s_fs_info;
2801         LIST_HEAD(garbage_list);
2802 
2803         down_write(&nilfs->ns_segctor_sem);
2804         if (nilfs->ns_writer) {
2805                 nilfs_segctor_destroy(nilfs->ns_writer);
2806                 nilfs->ns_writer = NULL;
2807         }
2808 
2809         /* Force to free the list of dirty files */
2810         spin_lock(&nilfs->ns_inode_lock);
2811         if (!list_empty(&nilfs->ns_dirty_files)) {
2812                 list_splice_init(&nilfs->ns_dirty_files, &garbage_list);
2813                 nilfs_msg(sb, KERN_WARNING,
2814                           "disposed unprocessed dirty file(s) when detaching log writer");
2815         }
2816         spin_unlock(&nilfs->ns_inode_lock);
2817         up_write(&nilfs->ns_segctor_sem);
2818 
2819         nilfs_dispose_list(nilfs, &garbage_list, 1);
2820 }
2821 

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