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

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  1 /*
  2  * segment.c - NILFS segment constructor.
  3  *
  4  * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
  5  *
  6  * This program is free software; you can redistribute it and/or modify
  7  * it under the terms of the GNU General Public License as published by
  8  * the Free Software Foundation; either version 2 of the License, or
  9  * (at your option) any later version.
 10  *
 11  * This program is distributed in the hope that it will be useful,
 12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 14  * GNU General Public License for more details.
 15  *
 16  * You should have received a copy of the GNU General Public License
 17  * along with this program; if not, write to the Free Software
 18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 19  *
 20  * Written by Ryusuke Konishi <ryusuke@osrg.net>
 21  *
 22  */
 23 
 24 #include <linux/pagemap.h>
 25 #include <linux/buffer_head.h>
 26 #include <linux/writeback.h>
 27 #include <linux/bio.h>
 28 #include <linux/completion.h>
 29 #include <linux/blkdev.h>
 30 #include <linux/backing-dev.h>
 31 #include <linux/freezer.h>
 32 #include <linux/kthread.h>
 33 #include <linux/crc32.h>
 34 #include <linux/pagevec.h>
 35 #include <linux/slab.h>
 36 #include "nilfs.h"
 37 #include "btnode.h"
 38 #include "page.h"
 39 #include "segment.h"
 40 #include "sufile.h"
 41 #include "cpfile.h"
 42 #include "ifile.h"
 43 #include "segbuf.h"
 44 
 45 
 46 /*
 47  * Segment constructor
 48  */
 49 #define SC_N_INODEVEC   16   /* Size of locally allocated inode vector */
 50 
 51 #define SC_MAX_SEGDELTA 64   /* Upper limit of the number of segments
 52                                 appended in collection retry loop */
 53 
 54 /* Construction mode */
 55 enum {
 56         SC_LSEG_SR = 1, /* Make a logical segment having a super root */
 57         SC_LSEG_DSYNC,  /* Flush data blocks of a given file and make
 58                            a logical segment without a super root */
 59         SC_FLUSH_FILE,  /* Flush data files, leads to segment writes without
 60                            creating a checkpoint */
 61         SC_FLUSH_DAT,   /* Flush DAT file. This also creates segments without
 62                            a checkpoint */
 63 };
 64 
 65 /* Stage numbers of dirty block collection */
 66 enum {
 67         NILFS_ST_INIT = 0,
 68         NILFS_ST_GC,            /* Collecting dirty blocks for GC */
 69         NILFS_ST_FILE,
 70         NILFS_ST_IFILE,
 71         NILFS_ST_CPFILE,
 72         NILFS_ST_SUFILE,
 73         NILFS_ST_DAT,
 74         NILFS_ST_SR,            /* Super root */
 75         NILFS_ST_DSYNC,         /* Data sync blocks */
 76         NILFS_ST_DONE,
 77 };
 78 
 79 /* State flags of collection */
 80 #define NILFS_CF_NODE           0x0001  /* Collecting node blocks */
 81 #define NILFS_CF_IFILE_STARTED  0x0002  /* IFILE stage has started */
 82 #define NILFS_CF_SUFREED        0x0004  /* segment usages has been freed */
 83 #define NILFS_CF_HISTORY_MASK   (NILFS_CF_IFILE_STARTED | NILFS_CF_SUFREED)
 84 
 85 /* Operations depending on the construction mode and file type */
 86 struct nilfs_sc_operations {
 87         int (*collect_data)(struct nilfs_sc_info *, struct buffer_head *,
 88                             struct inode *);
 89         int (*collect_node)(struct nilfs_sc_info *, struct buffer_head *,
 90                             struct inode *);
 91         int (*collect_bmap)(struct nilfs_sc_info *, struct buffer_head *,
 92                             struct inode *);
 93         void (*write_data_binfo)(struct nilfs_sc_info *,
 94                                  struct nilfs_segsum_pointer *,
 95                                  union nilfs_binfo *);
 96         void (*write_node_binfo)(struct nilfs_sc_info *,
 97                                  struct nilfs_segsum_pointer *,
 98                                  union nilfs_binfo *);
 99 };
100 
101 /*
102  * Other definitions
103  */
104 static void nilfs_segctor_start_timer(struct nilfs_sc_info *);
105 static void nilfs_segctor_do_flush(struct nilfs_sc_info *, int);
106 static void nilfs_segctor_do_immediate_flush(struct nilfs_sc_info *);
107 static void nilfs_dispose_list(struct the_nilfs *, struct list_head *, int);
108 
109 #define nilfs_cnt32_gt(a, b)   \
110         (typecheck(__u32, a) && typecheck(__u32, b) && \
111          ((__s32)(b) - (__s32)(a) < 0))
112 #define nilfs_cnt32_ge(a, b)   \
113         (typecheck(__u32, a) && typecheck(__u32, b) && \
114          ((__s32)(a) - (__s32)(b) >= 0))
115 #define nilfs_cnt32_lt(a, b)  nilfs_cnt32_gt(b, a)
116 #define nilfs_cnt32_le(a, b)  nilfs_cnt32_ge(b, a)
117 
118 static int nilfs_prepare_segment_lock(struct nilfs_transaction_info *ti)
119 {
120         struct nilfs_transaction_info *cur_ti = current->journal_info;
121         void *save = NULL;
122 
123         if (cur_ti) {
124                 if (cur_ti->ti_magic == NILFS_TI_MAGIC)
125                         return ++cur_ti->ti_count;
126                 else {
127                         /*
128                          * If journal_info field is occupied by other FS,
129                          * it is saved and will be restored on
130                          * nilfs_transaction_commit().
131                          */
132                         printk(KERN_WARNING
133                                "NILFS warning: journal info from a different "
134                                "FS\n");
135                         save = current->journal_info;
136                 }
137         }
138         if (!ti) {
139                 ti = kmem_cache_alloc(nilfs_transaction_cachep, GFP_NOFS);
140                 if (!ti)
141                         return -ENOMEM;
142                 ti->ti_flags = NILFS_TI_DYNAMIC_ALLOC;
143         } else {
144                 ti->ti_flags = 0;
145         }
146         ti->ti_count = 0;
147         ti->ti_save = save;
148         ti->ti_magic = NILFS_TI_MAGIC;
149         current->journal_info = ti;
150         return 0;
151 }
152 
153 /**
154  * nilfs_transaction_begin - start indivisible file operations.
155  * @sb: super block
156  * @ti: nilfs_transaction_info
157  * @vacancy_check: flags for vacancy rate checks
158  *
159  * nilfs_transaction_begin() acquires a reader/writer semaphore, called
160  * the segment semaphore, to make a segment construction and write tasks
161  * exclusive.  The function is used with nilfs_transaction_commit() in pairs.
162  * The region enclosed by these two functions can be nested.  To avoid a
163  * deadlock, the semaphore is only acquired or released in the outermost call.
164  *
165  * This function allocates a nilfs_transaction_info struct to keep context
166  * information on it.  It is initialized and hooked onto the current task in
167  * the outermost call.  If a pre-allocated struct is given to @ti, it is used
168  * instead; otherwise a new struct is assigned from a slab.
169  *
170  * When @vacancy_check flag is set, this function will check the amount of
171  * free space, and will wait for the GC to reclaim disk space if low capacity.
172  *
173  * Return Value: On success, 0 is returned. On error, one of the following
174  * negative error code is returned.
175  *
176  * %-ENOMEM - Insufficient memory available.
177  *
178  * %-ENOSPC - No space left on device
179  */
180 int nilfs_transaction_begin(struct super_block *sb,
181                             struct nilfs_transaction_info *ti,
182                             int vacancy_check)
183 {
184         struct the_nilfs *nilfs;
185         int ret = nilfs_prepare_segment_lock(ti);
186 
187         if (unlikely(ret < 0))
188                 return ret;
189         if (ret > 0)
190                 return 0;
191 
192         sb_start_intwrite(sb);
193 
194         nilfs = sb->s_fs_info;
195         down_read(&nilfs->ns_segctor_sem);
196         if (vacancy_check && nilfs_near_disk_full(nilfs)) {
197                 up_read(&nilfs->ns_segctor_sem);
198                 ret = -ENOSPC;
199                 goto failed;
200         }
201         return 0;
202 
203  failed:
204         ti = current->journal_info;
205         current->journal_info = ti->ti_save;
206         if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
207                 kmem_cache_free(nilfs_transaction_cachep, ti);
208         sb_end_intwrite(sb);
209         return ret;
210 }
211 
212 /**
213  * nilfs_transaction_commit - commit indivisible file operations.
214  * @sb: super block
215  *
216  * nilfs_transaction_commit() releases the read semaphore which is
217  * acquired by nilfs_transaction_begin(). This is only performed
218  * in outermost call of this function.  If a commit flag is set,
219  * nilfs_transaction_commit() sets a timer to start the segment
220  * constructor.  If a sync flag is set, it starts construction
221  * directly.
222  */
223 int nilfs_transaction_commit(struct super_block *sb)
224 {
225         struct nilfs_transaction_info *ti = current->journal_info;
226         struct the_nilfs *nilfs = sb->s_fs_info;
227         int err = 0;
228 
229         BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
230         ti->ti_flags |= NILFS_TI_COMMIT;
231         if (ti->ti_count > 0) {
232                 ti->ti_count--;
233                 return 0;
234         }
235         if (nilfs->ns_writer) {
236                 struct nilfs_sc_info *sci = nilfs->ns_writer;
237 
238                 if (ti->ti_flags & NILFS_TI_COMMIT)
239                         nilfs_segctor_start_timer(sci);
240                 if (atomic_read(&nilfs->ns_ndirtyblks) > sci->sc_watermark)
241                         nilfs_segctor_do_flush(sci, 0);
242         }
243         up_read(&nilfs->ns_segctor_sem);
244         current->journal_info = ti->ti_save;
245 
246         if (ti->ti_flags & NILFS_TI_SYNC)
247                 err = nilfs_construct_segment(sb);
248         if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
249                 kmem_cache_free(nilfs_transaction_cachep, ti);
250         sb_end_intwrite(sb);
251         return err;
252 }
253 
254 void nilfs_transaction_abort(struct super_block *sb)
255 {
256         struct nilfs_transaction_info *ti = current->journal_info;
257         struct the_nilfs *nilfs = sb->s_fs_info;
258 
259         BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
260         if (ti->ti_count > 0) {
261                 ti->ti_count--;
262                 return;
263         }
264         up_read(&nilfs->ns_segctor_sem);
265 
266         current->journal_info = ti->ti_save;
267         if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
268                 kmem_cache_free(nilfs_transaction_cachep, ti);
269         sb_end_intwrite(sb);
270 }
271 
272 void nilfs_relax_pressure_in_lock(struct super_block *sb)
273 {
274         struct the_nilfs *nilfs = sb->s_fs_info;
275         struct nilfs_sc_info *sci = nilfs->ns_writer;
276 
277         if (!sci || !sci->sc_flush_request)
278                 return;
279 
280         set_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags);
281         up_read(&nilfs->ns_segctor_sem);
282 
283         down_write(&nilfs->ns_segctor_sem);
284         if (sci->sc_flush_request &&
285             test_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags)) {
286                 struct nilfs_transaction_info *ti = current->journal_info;
287 
288                 ti->ti_flags |= NILFS_TI_WRITER;
289                 nilfs_segctor_do_immediate_flush(sci);
290                 ti->ti_flags &= ~NILFS_TI_WRITER;
291         }
292         downgrade_write(&nilfs->ns_segctor_sem);
293 }
294 
295 static void nilfs_transaction_lock(struct super_block *sb,
296                                    struct nilfs_transaction_info *ti,
297                                    int gcflag)
298 {
299         struct nilfs_transaction_info *cur_ti = current->journal_info;
300         struct the_nilfs *nilfs = sb->s_fs_info;
301         struct nilfs_sc_info *sci = nilfs->ns_writer;
302 
303         WARN_ON(cur_ti);
304         ti->ti_flags = NILFS_TI_WRITER;
305         ti->ti_count = 0;
306         ti->ti_save = cur_ti;
307         ti->ti_magic = NILFS_TI_MAGIC;
308         current->journal_info = ti;
309 
310         for (;;) {
311                 down_write(&nilfs->ns_segctor_sem);
312                 if (!test_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags))
313                         break;
314 
315                 nilfs_segctor_do_immediate_flush(sci);
316 
317                 up_write(&nilfs->ns_segctor_sem);
318                 yield();
319         }
320         if (gcflag)
321                 ti->ti_flags |= NILFS_TI_GC;
322 }
323 
324 static void nilfs_transaction_unlock(struct super_block *sb)
325 {
326         struct nilfs_transaction_info *ti = current->journal_info;
327         struct the_nilfs *nilfs = sb->s_fs_info;
328 
329         BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
330         BUG_ON(ti->ti_count > 0);
331 
332         up_write(&nilfs->ns_segctor_sem);
333         current->journal_info = ti->ti_save;
334 }
335 
336 static void *nilfs_segctor_map_segsum_entry(struct nilfs_sc_info *sci,
337                                             struct nilfs_segsum_pointer *ssp,
338                                             unsigned bytes)
339 {
340         struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
341         unsigned blocksize = sci->sc_super->s_blocksize;
342         void *p;
343 
344         if (unlikely(ssp->offset + bytes > blocksize)) {
345                 ssp->offset = 0;
346                 BUG_ON(NILFS_SEGBUF_BH_IS_LAST(ssp->bh,
347                                                &segbuf->sb_segsum_buffers));
348                 ssp->bh = NILFS_SEGBUF_NEXT_BH(ssp->bh);
349         }
350         p = ssp->bh->b_data + ssp->offset;
351         ssp->offset += bytes;
352         return p;
353 }
354 
355 /**
356  * nilfs_segctor_reset_segment_buffer - reset the current segment buffer
357  * @sci: nilfs_sc_info
358  */
359 static int nilfs_segctor_reset_segment_buffer(struct nilfs_sc_info *sci)
360 {
361         struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
362         struct buffer_head *sumbh;
363         unsigned sumbytes;
364         unsigned flags = 0;
365         int err;
366 
367         if (nilfs_doing_gc())
368                 flags = NILFS_SS_GC;
369         err = nilfs_segbuf_reset(segbuf, flags, sci->sc_seg_ctime, sci->sc_cno);
370         if (unlikely(err))
371                 return err;
372 
373         sumbh = NILFS_SEGBUF_FIRST_BH(&segbuf->sb_segsum_buffers);
374         sumbytes = segbuf->sb_sum.sumbytes;
375         sci->sc_finfo_ptr.bh = sumbh;  sci->sc_finfo_ptr.offset = sumbytes;
376         sci->sc_binfo_ptr.bh = sumbh;  sci->sc_binfo_ptr.offset = sumbytes;
377         sci->sc_blk_cnt = sci->sc_datablk_cnt = 0;
378         return 0;
379 }
380 
381 static int nilfs_segctor_feed_segment(struct nilfs_sc_info *sci)
382 {
383         sci->sc_nblk_this_inc += sci->sc_curseg->sb_sum.nblocks;
384         if (NILFS_SEGBUF_IS_LAST(sci->sc_curseg, &sci->sc_segbufs))
385                 return -E2BIG; /* The current segment is filled up
386                                   (internal code) */
387         sci->sc_curseg = NILFS_NEXT_SEGBUF(sci->sc_curseg);
388         return nilfs_segctor_reset_segment_buffer(sci);
389 }
390 
391 static int nilfs_segctor_add_super_root(struct nilfs_sc_info *sci)
392 {
393         struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
394         int err;
395 
396         if (segbuf->sb_sum.nblocks >= segbuf->sb_rest_blocks) {
397                 err = nilfs_segctor_feed_segment(sci);
398                 if (err)
399                         return err;
400                 segbuf = sci->sc_curseg;
401         }
402         err = nilfs_segbuf_extend_payload(segbuf, &segbuf->sb_super_root);
403         if (likely(!err))
404                 segbuf->sb_sum.flags |= NILFS_SS_SR;
405         return err;
406 }
407 
408 /*
409  * Functions for making segment summary and payloads
410  */
411 static int nilfs_segctor_segsum_block_required(
412         struct nilfs_sc_info *sci, const struct nilfs_segsum_pointer *ssp,
413         unsigned binfo_size)
414 {
415         unsigned blocksize = sci->sc_super->s_blocksize;
416         /* Size of finfo and binfo is enough small against blocksize */
417 
418         return ssp->offset + binfo_size +
419                 (!sci->sc_blk_cnt ? sizeof(struct nilfs_finfo) : 0) >
420                 blocksize;
421 }
422 
423 static void nilfs_segctor_begin_finfo(struct nilfs_sc_info *sci,
424                                       struct inode *inode)
425 {
426         sci->sc_curseg->sb_sum.nfinfo++;
427         sci->sc_binfo_ptr = sci->sc_finfo_ptr;
428         nilfs_segctor_map_segsum_entry(
429                 sci, &sci->sc_binfo_ptr, sizeof(struct nilfs_finfo));
430 
431         if (NILFS_I(inode)->i_root &&
432             !test_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags))
433                 set_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
434         /* skip finfo */
435 }
436 
437 static void nilfs_segctor_end_finfo(struct nilfs_sc_info *sci,
438                                     struct inode *inode)
439 {
440         struct nilfs_finfo *finfo;
441         struct nilfs_inode_info *ii;
442         struct nilfs_segment_buffer *segbuf;
443         __u64 cno;
444 
445         if (sci->sc_blk_cnt == 0)
446                 return;
447 
448         ii = NILFS_I(inode);
449 
450         if (test_bit(NILFS_I_GCINODE, &ii->i_state))
451                 cno = ii->i_cno;
452         else if (NILFS_ROOT_METADATA_FILE(inode->i_ino))
453                 cno = 0;
454         else
455                 cno = sci->sc_cno;
456 
457         finfo = nilfs_segctor_map_segsum_entry(sci, &sci->sc_finfo_ptr,
458                                                  sizeof(*finfo));
459         finfo->fi_ino = cpu_to_le64(inode->i_ino);
460         finfo->fi_nblocks = cpu_to_le32(sci->sc_blk_cnt);
461         finfo->fi_ndatablk = cpu_to_le32(sci->sc_datablk_cnt);
462         finfo->fi_cno = cpu_to_le64(cno);
463 
464         segbuf = sci->sc_curseg;
465         segbuf->sb_sum.sumbytes = sci->sc_binfo_ptr.offset +
466                 sci->sc_super->s_blocksize * (segbuf->sb_sum.nsumblk - 1);
467         sci->sc_finfo_ptr = sci->sc_binfo_ptr;
468         sci->sc_blk_cnt = sci->sc_datablk_cnt = 0;
469 }
470 
471 static int nilfs_segctor_add_file_block(struct nilfs_sc_info *sci,
472                                         struct buffer_head *bh,
473                                         struct inode *inode,
474                                         unsigned binfo_size)
475 {
476         struct nilfs_segment_buffer *segbuf;
477         int required, err = 0;
478 
479  retry:
480         segbuf = sci->sc_curseg;
481         required = nilfs_segctor_segsum_block_required(
482                 sci, &sci->sc_binfo_ptr, binfo_size);
483         if (segbuf->sb_sum.nblocks + required + 1 > segbuf->sb_rest_blocks) {
484                 nilfs_segctor_end_finfo(sci, inode);
485                 err = nilfs_segctor_feed_segment(sci);
486                 if (err)
487                         return err;
488                 goto retry;
489         }
490         if (unlikely(required)) {
491                 err = nilfs_segbuf_extend_segsum(segbuf);
492                 if (unlikely(err))
493                         goto failed;
494         }
495         if (sci->sc_blk_cnt == 0)
496                 nilfs_segctor_begin_finfo(sci, inode);
497 
498         nilfs_segctor_map_segsum_entry(sci, &sci->sc_binfo_ptr, binfo_size);
499         /* Substitution to vblocknr is delayed until update_blocknr() */
500         nilfs_segbuf_add_file_buffer(segbuf, bh);
501         sci->sc_blk_cnt++;
502  failed:
503         return err;
504 }
505 
506 /*
507  * Callback functions that enumerate, mark, and collect dirty blocks
508  */
509 static int nilfs_collect_file_data(struct nilfs_sc_info *sci,
510                                    struct buffer_head *bh, struct inode *inode)
511 {
512         int err;
513 
514         err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
515         if (err < 0)
516                 return err;
517 
518         err = nilfs_segctor_add_file_block(sci, bh, inode,
519                                            sizeof(struct nilfs_binfo_v));
520         if (!err)
521                 sci->sc_datablk_cnt++;
522         return err;
523 }
524 
525 static int nilfs_collect_file_node(struct nilfs_sc_info *sci,
526                                    struct buffer_head *bh,
527                                    struct inode *inode)
528 {
529         return nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
530 }
531 
532 static int nilfs_collect_file_bmap(struct nilfs_sc_info *sci,
533                                    struct buffer_head *bh,
534                                    struct inode *inode)
535 {
536         WARN_ON(!buffer_dirty(bh));
537         return nilfs_segctor_add_file_block(sci, bh, inode, sizeof(__le64));
538 }
539 
540 static void nilfs_write_file_data_binfo(struct nilfs_sc_info *sci,
541                                         struct nilfs_segsum_pointer *ssp,
542                                         union nilfs_binfo *binfo)
543 {
544         struct nilfs_binfo_v *binfo_v = nilfs_segctor_map_segsum_entry(
545                 sci, ssp, sizeof(*binfo_v));
546         *binfo_v = binfo->bi_v;
547 }
548 
549 static void nilfs_write_file_node_binfo(struct nilfs_sc_info *sci,
550                                         struct nilfs_segsum_pointer *ssp,
551                                         union nilfs_binfo *binfo)
552 {
553         __le64 *vblocknr = nilfs_segctor_map_segsum_entry(
554                 sci, ssp, sizeof(*vblocknr));
555         *vblocknr = binfo->bi_v.bi_vblocknr;
556 }
557 
558 static struct nilfs_sc_operations nilfs_sc_file_ops = {
559         .collect_data = nilfs_collect_file_data,
560         .collect_node = nilfs_collect_file_node,
561         .collect_bmap = nilfs_collect_file_bmap,
562         .write_data_binfo = nilfs_write_file_data_binfo,
563         .write_node_binfo = nilfs_write_file_node_binfo,
564 };
565 
566 static int nilfs_collect_dat_data(struct nilfs_sc_info *sci,
567                                   struct buffer_head *bh, struct inode *inode)
568 {
569         int err;
570 
571         err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
572         if (err < 0)
573                 return err;
574 
575         err = nilfs_segctor_add_file_block(sci, bh, inode, sizeof(__le64));
576         if (!err)
577                 sci->sc_datablk_cnt++;
578         return err;
579 }
580 
581 static int nilfs_collect_dat_bmap(struct nilfs_sc_info *sci,
582                                   struct buffer_head *bh, struct inode *inode)
583 {
584         WARN_ON(!buffer_dirty(bh));
585         return nilfs_segctor_add_file_block(sci, bh, inode,
586                                             sizeof(struct nilfs_binfo_dat));
587 }
588 
589 static void nilfs_write_dat_data_binfo(struct nilfs_sc_info *sci,
590                                        struct nilfs_segsum_pointer *ssp,
591                                        union nilfs_binfo *binfo)
592 {
593         __le64 *blkoff = nilfs_segctor_map_segsum_entry(sci, ssp,
594                                                           sizeof(*blkoff));
595         *blkoff = binfo->bi_dat.bi_blkoff;
596 }
597 
598 static void nilfs_write_dat_node_binfo(struct nilfs_sc_info *sci,
599                                        struct nilfs_segsum_pointer *ssp,
600                                        union nilfs_binfo *binfo)
601 {
602         struct nilfs_binfo_dat *binfo_dat =
603                 nilfs_segctor_map_segsum_entry(sci, ssp, sizeof(*binfo_dat));
604         *binfo_dat = binfo->bi_dat;
605 }
606 
607 static struct nilfs_sc_operations nilfs_sc_dat_ops = {
608         .collect_data = nilfs_collect_dat_data,
609         .collect_node = nilfs_collect_file_node,
610         .collect_bmap = nilfs_collect_dat_bmap,
611         .write_data_binfo = nilfs_write_dat_data_binfo,
612         .write_node_binfo = nilfs_write_dat_node_binfo,
613 };
614 
615 static struct nilfs_sc_operations nilfs_sc_dsync_ops = {
616         .collect_data = nilfs_collect_file_data,
617         .collect_node = NULL,
618         .collect_bmap = NULL,
619         .write_data_binfo = nilfs_write_file_data_binfo,
620         .write_node_binfo = NULL,
621 };
622 
623 static size_t nilfs_lookup_dirty_data_buffers(struct inode *inode,
624                                               struct list_head *listp,
625                                               size_t nlimit,
626                                               loff_t start, loff_t end)
627 {
628         struct address_space *mapping = inode->i_mapping;
629         struct pagevec pvec;
630         pgoff_t index = 0, last = ULONG_MAX;
631         size_t ndirties = 0;
632         int i;
633 
634         if (unlikely(start != 0 || end != LLONG_MAX)) {
635                 /*
636                  * A valid range is given for sync-ing data pages. The
637                  * range is rounded to per-page; extra dirty buffers
638                  * may be included if blocksize < pagesize.
639                  */
640                 index = start >> PAGE_SHIFT;
641                 last = end >> PAGE_SHIFT;
642         }
643         pagevec_init(&pvec, 0);
644  repeat:
645         if (unlikely(index > last) ||
646             !pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
647                                 min_t(pgoff_t, last - index,
648                                       PAGEVEC_SIZE - 1) + 1))
649                 return ndirties;
650 
651         for (i = 0; i < pagevec_count(&pvec); i++) {
652                 struct buffer_head *bh, *head;
653                 struct page *page = pvec.pages[i];
654 
655                 if (unlikely(page->index > last))
656                         break;
657 
658                 lock_page(page);
659                 if (!page_has_buffers(page))
660                         create_empty_buffers(page, 1 << inode->i_blkbits, 0);
661                 unlock_page(page);
662 
663                 bh = head = page_buffers(page);
664                 do {
665                         if (!buffer_dirty(bh) || buffer_async_write(bh))
666                                 continue;
667                         get_bh(bh);
668                         list_add_tail(&bh->b_assoc_buffers, listp);
669                         ndirties++;
670                         if (unlikely(ndirties >= nlimit)) {
671                                 pagevec_release(&pvec);
672                                 cond_resched();
673                                 return ndirties;
674                         }
675                 } while (bh = bh->b_this_page, bh != head);
676         }
677         pagevec_release(&pvec);
678         cond_resched();
679         goto repeat;
680 }
681 
682 static void nilfs_lookup_dirty_node_buffers(struct inode *inode,
683                                             struct list_head *listp)
684 {
685         struct nilfs_inode_info *ii = NILFS_I(inode);
686         struct address_space *mapping = &ii->i_btnode_cache;
687         struct pagevec pvec;
688         struct buffer_head *bh, *head;
689         unsigned int i;
690         pgoff_t index = 0;
691 
692         pagevec_init(&pvec, 0);
693 
694         while (pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
695                                   PAGEVEC_SIZE)) {
696                 for (i = 0; i < pagevec_count(&pvec); i++) {
697                         bh = head = page_buffers(pvec.pages[i]);
698                         do {
699                                 if (buffer_dirty(bh) &&
700                                                 !buffer_async_write(bh)) {
701                                         get_bh(bh);
702                                         list_add_tail(&bh->b_assoc_buffers,
703                                                       listp);
704                                 }
705                                 bh = bh->b_this_page;
706                         } while (bh != head);
707                 }
708                 pagevec_release(&pvec);
709                 cond_resched();
710         }
711 }
712 
713 static void nilfs_dispose_list(struct the_nilfs *nilfs,
714                                struct list_head *head, int force)
715 {
716         struct nilfs_inode_info *ii, *n;
717         struct nilfs_inode_info *ivec[SC_N_INODEVEC], **pii;
718         unsigned nv = 0;
719 
720         while (!list_empty(head)) {
721                 spin_lock(&nilfs->ns_inode_lock);
722                 list_for_each_entry_safe(ii, n, head, i_dirty) {
723                         list_del_init(&ii->i_dirty);
724                         if (force) {
725                                 if (unlikely(ii->i_bh)) {
726                                         brelse(ii->i_bh);
727                                         ii->i_bh = NULL;
728                                 }
729                         } else if (test_bit(NILFS_I_DIRTY, &ii->i_state)) {
730                                 set_bit(NILFS_I_QUEUED, &ii->i_state);
731                                 list_add_tail(&ii->i_dirty,
732                                               &nilfs->ns_dirty_files);
733                                 continue;
734                         }
735                         ivec[nv++] = ii;
736                         if (nv == SC_N_INODEVEC)
737                                 break;
738                 }
739                 spin_unlock(&nilfs->ns_inode_lock);
740 
741                 for (pii = ivec; nv > 0; pii++, nv--)
742                         iput(&(*pii)->vfs_inode);
743         }
744 }
745 
746 static void nilfs_iput_work_func(struct work_struct *work)
747 {
748         struct nilfs_sc_info *sci = container_of(work, struct nilfs_sc_info,
749                                                  sc_iput_work);
750         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
751 
752         nilfs_dispose_list(nilfs, &sci->sc_iput_queue, 0);
753 }
754 
755 static int nilfs_test_metadata_dirty(struct the_nilfs *nilfs,
756                                      struct nilfs_root *root)
757 {
758         int ret = 0;
759 
760         if (nilfs_mdt_fetch_dirty(root->ifile))
761                 ret++;
762         if (nilfs_mdt_fetch_dirty(nilfs->ns_cpfile))
763                 ret++;
764         if (nilfs_mdt_fetch_dirty(nilfs->ns_sufile))
765                 ret++;
766         if ((ret || nilfs_doing_gc()) && nilfs_mdt_fetch_dirty(nilfs->ns_dat))
767                 ret++;
768         return ret;
769 }
770 
771 static int nilfs_segctor_clean(struct nilfs_sc_info *sci)
772 {
773         return list_empty(&sci->sc_dirty_files) &&
774                 !test_bit(NILFS_SC_DIRTY, &sci->sc_flags) &&
775                 sci->sc_nfreesegs == 0 &&
776                 (!nilfs_doing_gc() || list_empty(&sci->sc_gc_inodes));
777 }
778 
779 static int nilfs_segctor_confirm(struct nilfs_sc_info *sci)
780 {
781         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
782         int ret = 0;
783 
784         if (nilfs_test_metadata_dirty(nilfs, sci->sc_root))
785                 set_bit(NILFS_SC_DIRTY, &sci->sc_flags);
786 
787         spin_lock(&nilfs->ns_inode_lock);
788         if (list_empty(&nilfs->ns_dirty_files) && nilfs_segctor_clean(sci))
789                 ret++;
790 
791         spin_unlock(&nilfs->ns_inode_lock);
792         return ret;
793 }
794 
795 static void nilfs_segctor_clear_metadata_dirty(struct nilfs_sc_info *sci)
796 {
797         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
798 
799         nilfs_mdt_clear_dirty(sci->sc_root->ifile);
800         nilfs_mdt_clear_dirty(nilfs->ns_cpfile);
801         nilfs_mdt_clear_dirty(nilfs->ns_sufile);
802         nilfs_mdt_clear_dirty(nilfs->ns_dat);
803 }
804 
805 static int nilfs_segctor_create_checkpoint(struct nilfs_sc_info *sci)
806 {
807         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
808         struct buffer_head *bh_cp;
809         struct nilfs_checkpoint *raw_cp;
810         int err;
811 
812         /* XXX: this interface will be changed */
813         err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, 1,
814                                           &raw_cp, &bh_cp);
815         if (likely(!err)) {
816                 /* The following code is duplicated with cpfile.  But, it is
817                    needed to collect the checkpoint even if it was not newly
818                    created */
819                 mark_buffer_dirty(bh_cp);
820                 nilfs_mdt_mark_dirty(nilfs->ns_cpfile);
821                 nilfs_cpfile_put_checkpoint(
822                         nilfs->ns_cpfile, nilfs->ns_cno, bh_cp);
823         } else
824                 WARN_ON(err == -EINVAL || err == -ENOENT);
825 
826         return err;
827 }
828 
829 static int nilfs_segctor_fill_in_checkpoint(struct nilfs_sc_info *sci)
830 {
831         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
832         struct buffer_head *bh_cp;
833         struct nilfs_checkpoint *raw_cp;
834         int err;
835 
836         err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, 0,
837                                           &raw_cp, &bh_cp);
838         if (unlikely(err)) {
839                 WARN_ON(err == -EINVAL || err == -ENOENT);
840                 goto failed_ibh;
841         }
842         raw_cp->cp_snapshot_list.ssl_next = 0;
843         raw_cp->cp_snapshot_list.ssl_prev = 0;
844         raw_cp->cp_inodes_count =
845                 cpu_to_le64(atomic64_read(&sci->sc_root->inodes_count));
846         raw_cp->cp_blocks_count =
847                 cpu_to_le64(atomic64_read(&sci->sc_root->blocks_count));
848         raw_cp->cp_nblk_inc =
849                 cpu_to_le64(sci->sc_nblk_inc + sci->sc_nblk_this_inc);
850         raw_cp->cp_create = cpu_to_le64(sci->sc_seg_ctime);
851         raw_cp->cp_cno = cpu_to_le64(nilfs->ns_cno);
852 
853         if (test_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags))
854                 nilfs_checkpoint_clear_minor(raw_cp);
855         else
856                 nilfs_checkpoint_set_minor(raw_cp);
857 
858         nilfs_write_inode_common(sci->sc_root->ifile,
859                                  &raw_cp->cp_ifile_inode, 1);
860         nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, bh_cp);
861         return 0;
862 
863  failed_ibh:
864         return err;
865 }
866 
867 static void nilfs_fill_in_file_bmap(struct inode *ifile,
868                                     struct nilfs_inode_info *ii)
869 
870 {
871         struct buffer_head *ibh;
872         struct nilfs_inode *raw_inode;
873 
874         if (test_bit(NILFS_I_BMAP, &ii->i_state)) {
875                 ibh = ii->i_bh;
876                 BUG_ON(!ibh);
877                 raw_inode = nilfs_ifile_map_inode(ifile, ii->vfs_inode.i_ino,
878                                                   ibh);
879                 nilfs_bmap_write(ii->i_bmap, raw_inode);
880                 nilfs_ifile_unmap_inode(ifile, ii->vfs_inode.i_ino, ibh);
881         }
882 }
883 
884 static void nilfs_segctor_fill_in_file_bmap(struct nilfs_sc_info *sci)
885 {
886         struct nilfs_inode_info *ii;
887 
888         list_for_each_entry(ii, &sci->sc_dirty_files, i_dirty) {
889                 nilfs_fill_in_file_bmap(sci->sc_root->ifile, ii);
890                 set_bit(NILFS_I_COLLECTED, &ii->i_state);
891         }
892 }
893 
894 static void nilfs_segctor_fill_in_super_root(struct nilfs_sc_info *sci,
895                                              struct the_nilfs *nilfs)
896 {
897         struct buffer_head *bh_sr;
898         struct nilfs_super_root *raw_sr;
899         unsigned isz, srsz;
900 
901         bh_sr = NILFS_LAST_SEGBUF(&sci->sc_segbufs)->sb_super_root;
902         raw_sr = (struct nilfs_super_root *)bh_sr->b_data;
903         isz = nilfs->ns_inode_size;
904         srsz = NILFS_SR_BYTES(isz);
905 
906         raw_sr->sr_bytes = cpu_to_le16(srsz);
907         raw_sr->sr_nongc_ctime
908                 = cpu_to_le64(nilfs_doing_gc() ?
909                               nilfs->ns_nongc_ctime : sci->sc_seg_ctime);
910         raw_sr->sr_flags = 0;
911 
912         nilfs_write_inode_common(nilfs->ns_dat, (void *)raw_sr +
913                                  NILFS_SR_DAT_OFFSET(isz), 1);
914         nilfs_write_inode_common(nilfs->ns_cpfile, (void *)raw_sr +
915                                  NILFS_SR_CPFILE_OFFSET(isz), 1);
916         nilfs_write_inode_common(nilfs->ns_sufile, (void *)raw_sr +
917                                  NILFS_SR_SUFILE_OFFSET(isz), 1);
918         memset((void *)raw_sr + srsz, 0, nilfs->ns_blocksize - srsz);
919 }
920 
921 static void nilfs_redirty_inodes(struct list_head *head)
922 {
923         struct nilfs_inode_info *ii;
924 
925         list_for_each_entry(ii, head, i_dirty) {
926                 if (test_bit(NILFS_I_COLLECTED, &ii->i_state))
927                         clear_bit(NILFS_I_COLLECTED, &ii->i_state);
928         }
929 }
930 
931 static void nilfs_drop_collected_inodes(struct list_head *head)
932 {
933         struct nilfs_inode_info *ii;
934 
935         list_for_each_entry(ii, head, i_dirty) {
936                 if (!test_and_clear_bit(NILFS_I_COLLECTED, &ii->i_state))
937                         continue;
938 
939                 clear_bit(NILFS_I_INODE_DIRTY, &ii->i_state);
940                 set_bit(NILFS_I_UPDATED, &ii->i_state);
941         }
942 }
943 
944 static int nilfs_segctor_apply_buffers(struct nilfs_sc_info *sci,
945                                        struct inode *inode,
946                                        struct list_head *listp,
947                                        int (*collect)(struct nilfs_sc_info *,
948                                                       struct buffer_head *,
949                                                       struct inode *))
950 {
951         struct buffer_head *bh, *n;
952         int err = 0;
953 
954         if (collect) {
955                 list_for_each_entry_safe(bh, n, listp, b_assoc_buffers) {
956                         list_del_init(&bh->b_assoc_buffers);
957                         err = collect(sci, bh, inode);
958                         brelse(bh);
959                         if (unlikely(err))
960                                 goto dispose_buffers;
961                 }
962                 return 0;
963         }
964 
965  dispose_buffers:
966         while (!list_empty(listp)) {
967                 bh = list_first_entry(listp, struct buffer_head,
968                                       b_assoc_buffers);
969                 list_del_init(&bh->b_assoc_buffers);
970                 brelse(bh);
971         }
972         return err;
973 }
974 
975 static size_t nilfs_segctor_buffer_rest(struct nilfs_sc_info *sci)
976 {
977         /* Remaining number of blocks within segment buffer */
978         return sci->sc_segbuf_nblocks -
979                 (sci->sc_nblk_this_inc + sci->sc_curseg->sb_sum.nblocks);
980 }
981 
982 static int nilfs_segctor_scan_file(struct nilfs_sc_info *sci,
983                                    struct inode *inode,
984                                    struct nilfs_sc_operations *sc_ops)
985 {
986         LIST_HEAD(data_buffers);
987         LIST_HEAD(node_buffers);
988         int err;
989 
990         if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
991                 size_t n, rest = nilfs_segctor_buffer_rest(sci);
992 
993                 n = nilfs_lookup_dirty_data_buffers(
994                         inode, &data_buffers, rest + 1, 0, LLONG_MAX);
995                 if (n > rest) {
996                         err = nilfs_segctor_apply_buffers(
997                                 sci, inode, &data_buffers,
998                                 sc_ops->collect_data);
999                         BUG_ON(!err); /* always receive -E2BIG or true error */
1000                         goto break_or_fail;
1001                 }
1002         }
1003         nilfs_lookup_dirty_node_buffers(inode, &node_buffers);
1004 
1005         if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
1006                 err = nilfs_segctor_apply_buffers(
1007                         sci, inode, &data_buffers, sc_ops->collect_data);
1008                 if (unlikely(err)) {
1009                         /* dispose node list */
1010                         nilfs_segctor_apply_buffers(
1011                                 sci, inode, &node_buffers, NULL);
1012                         goto break_or_fail;
1013                 }
1014                 sci->sc_stage.flags |= NILFS_CF_NODE;
1015         }
1016         /* Collect node */
1017         err = nilfs_segctor_apply_buffers(
1018                 sci, inode, &node_buffers, sc_ops->collect_node);
1019         if (unlikely(err))
1020                 goto break_or_fail;
1021 
1022         nilfs_bmap_lookup_dirty_buffers(NILFS_I(inode)->i_bmap, &node_buffers);
1023         err = nilfs_segctor_apply_buffers(
1024                 sci, inode, &node_buffers, sc_ops->collect_bmap);
1025         if (unlikely(err))
1026                 goto break_or_fail;
1027 
1028         nilfs_segctor_end_finfo(sci, inode);
1029         sci->sc_stage.flags &= ~NILFS_CF_NODE;
1030 
1031  break_or_fail:
1032         return err;
1033 }
1034 
1035 static int nilfs_segctor_scan_file_dsync(struct nilfs_sc_info *sci,
1036                                          struct inode *inode)
1037 {
1038         LIST_HEAD(data_buffers);
1039         size_t n, rest = nilfs_segctor_buffer_rest(sci);
1040         int err;
1041 
1042         n = nilfs_lookup_dirty_data_buffers(inode, &data_buffers, rest + 1,
1043                                             sci->sc_dsync_start,
1044                                             sci->sc_dsync_end);
1045 
1046         err = nilfs_segctor_apply_buffers(sci, inode, &data_buffers,
1047                                           nilfs_collect_file_data);
1048         if (!err) {
1049                 nilfs_segctor_end_finfo(sci, inode);
1050                 BUG_ON(n > rest);
1051                 /* always receive -E2BIG or true error if n > rest */
1052         }
1053         return err;
1054 }
1055 
1056 static int nilfs_segctor_collect_blocks(struct nilfs_sc_info *sci, int mode)
1057 {
1058         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
1059         struct list_head *head;
1060         struct nilfs_inode_info *ii;
1061         size_t ndone;
1062         int err = 0;
1063 
1064         switch (sci->sc_stage.scnt) {
1065         case NILFS_ST_INIT:
1066                 /* Pre-processes */
1067                 sci->sc_stage.flags = 0;
1068 
1069                 if (!test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags)) {
1070                         sci->sc_nblk_inc = 0;
1071                         sci->sc_curseg->sb_sum.flags = NILFS_SS_LOGBGN;
1072                         if (mode == SC_LSEG_DSYNC) {
1073                                 sci->sc_stage.scnt = NILFS_ST_DSYNC;
1074                                 goto dsync_mode;
1075                         }
1076                 }
1077 
1078                 sci->sc_stage.dirty_file_ptr = NULL;
1079                 sci->sc_stage.gc_inode_ptr = NULL;
1080                 if (mode == SC_FLUSH_DAT) {
1081                         sci->sc_stage.scnt = NILFS_ST_DAT;
1082                         goto dat_stage;
1083                 }
1084                 sci->sc_stage.scnt++;  /* Fall through */
1085         case NILFS_ST_GC:
1086                 if (nilfs_doing_gc()) {
1087                         head = &sci->sc_gc_inodes;
1088                         ii = list_prepare_entry(sci->sc_stage.gc_inode_ptr,
1089                                                 head, i_dirty);
1090                         list_for_each_entry_continue(ii, head, i_dirty) {
1091                                 err = nilfs_segctor_scan_file(
1092                                         sci, &ii->vfs_inode,
1093                                         &nilfs_sc_file_ops);
1094                                 if (unlikely(err)) {
1095                                         sci->sc_stage.gc_inode_ptr = list_entry(
1096                                                 ii->i_dirty.prev,
1097                                                 struct nilfs_inode_info,
1098                                                 i_dirty);
1099                                         goto break_or_fail;
1100                                 }
1101                                 set_bit(NILFS_I_COLLECTED, &ii->i_state);
1102                         }
1103                         sci->sc_stage.gc_inode_ptr = NULL;
1104                 }
1105                 sci->sc_stage.scnt++;  /* Fall through */
1106         case NILFS_ST_FILE:
1107                 head = &sci->sc_dirty_files;
1108                 ii = list_prepare_entry(sci->sc_stage.dirty_file_ptr, head,
1109                                         i_dirty);
1110                 list_for_each_entry_continue(ii, head, i_dirty) {
1111                         clear_bit(NILFS_I_DIRTY, &ii->i_state);
1112 
1113                         err = nilfs_segctor_scan_file(sci, &ii->vfs_inode,
1114                                                       &nilfs_sc_file_ops);
1115                         if (unlikely(err)) {
1116                                 sci->sc_stage.dirty_file_ptr =
1117                                         list_entry(ii->i_dirty.prev,
1118                                                    struct nilfs_inode_info,
1119                                                    i_dirty);
1120                                 goto break_or_fail;
1121                         }
1122                         /* sci->sc_stage.dirty_file_ptr = NILFS_I(inode); */
1123                         /* XXX: required ? */
1124                 }
1125                 sci->sc_stage.dirty_file_ptr = NULL;
1126                 if (mode == SC_FLUSH_FILE) {
1127                         sci->sc_stage.scnt = NILFS_ST_DONE;
1128                         return 0;
1129                 }
1130                 sci->sc_stage.scnt++;
1131                 sci->sc_stage.flags |= NILFS_CF_IFILE_STARTED;
1132                 /* Fall through */
1133         case NILFS_ST_IFILE:
1134                 err = nilfs_segctor_scan_file(sci, sci->sc_root->ifile,
1135                                               &nilfs_sc_file_ops);
1136                 if (unlikely(err))
1137                         break;
1138                 sci->sc_stage.scnt++;
1139                 /* Creating a checkpoint */
1140                 err = nilfs_segctor_create_checkpoint(sci);
1141                 if (unlikely(err))
1142                         break;
1143                 /* Fall through */
1144         case NILFS_ST_CPFILE:
1145                 err = nilfs_segctor_scan_file(sci, nilfs->ns_cpfile,
1146                                               &nilfs_sc_file_ops);
1147                 if (unlikely(err))
1148                         break;
1149                 sci->sc_stage.scnt++;  /* Fall through */
1150         case NILFS_ST_SUFILE:
1151                 err = nilfs_sufile_freev(nilfs->ns_sufile, sci->sc_freesegs,
1152                                          sci->sc_nfreesegs, &ndone);
1153                 if (unlikely(err)) {
1154                         nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1155                                                   sci->sc_freesegs, ndone,
1156                                                   NULL);
1157                         break;
1158                 }
1159                 sci->sc_stage.flags |= NILFS_CF_SUFREED;
1160 
1161                 err = nilfs_segctor_scan_file(sci, nilfs->ns_sufile,
1162                                               &nilfs_sc_file_ops);
1163                 if (unlikely(err))
1164                         break;
1165                 sci->sc_stage.scnt++;  /* Fall through */
1166         case NILFS_ST_DAT:
1167  dat_stage:
1168                 err = nilfs_segctor_scan_file(sci, nilfs->ns_dat,
1169                                               &nilfs_sc_dat_ops);
1170                 if (unlikely(err))
1171                         break;
1172                 if (mode == SC_FLUSH_DAT) {
1173                         sci->sc_stage.scnt = NILFS_ST_DONE;
1174                         return 0;
1175                 }
1176                 sci->sc_stage.scnt++;  /* Fall through */
1177         case NILFS_ST_SR:
1178                 if (mode == SC_LSEG_SR) {
1179                         /* Appending a super root */
1180                         err = nilfs_segctor_add_super_root(sci);
1181                         if (unlikely(err))
1182                                 break;
1183                 }
1184                 /* End of a logical segment */
1185                 sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
1186                 sci->sc_stage.scnt = NILFS_ST_DONE;
1187                 return 0;
1188         case NILFS_ST_DSYNC:
1189  dsync_mode:
1190                 sci->sc_curseg->sb_sum.flags |= NILFS_SS_SYNDT;
1191                 ii = sci->sc_dsync_inode;
1192                 if (!test_bit(NILFS_I_BUSY, &ii->i_state))
1193                         break;
1194 
1195                 err = nilfs_segctor_scan_file_dsync(sci, &ii->vfs_inode);
1196                 if (unlikely(err))
1197                         break;
1198                 sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
1199                 sci->sc_stage.scnt = NILFS_ST_DONE;
1200                 return 0;
1201         case NILFS_ST_DONE:
1202                 return 0;
1203         default:
1204                 BUG();
1205         }
1206 
1207  break_or_fail:
1208         return err;
1209 }
1210 
1211 /**
1212  * nilfs_segctor_begin_construction - setup segment buffer to make a new log
1213  * @sci: nilfs_sc_info
1214  * @nilfs: nilfs object
1215  */
1216 static int nilfs_segctor_begin_construction(struct nilfs_sc_info *sci,
1217                                             struct the_nilfs *nilfs)
1218 {
1219         struct nilfs_segment_buffer *segbuf, *prev;
1220         __u64 nextnum;
1221         int err, alloc = 0;
1222 
1223         segbuf = nilfs_segbuf_new(sci->sc_super);
1224         if (unlikely(!segbuf))
1225                 return -ENOMEM;
1226 
1227         if (list_empty(&sci->sc_write_logs)) {
1228                 nilfs_segbuf_map(segbuf, nilfs->ns_segnum,
1229                                  nilfs->ns_pseg_offset, nilfs);
1230                 if (segbuf->sb_rest_blocks < NILFS_PSEG_MIN_BLOCKS) {
1231                         nilfs_shift_to_next_segment(nilfs);
1232                         nilfs_segbuf_map(segbuf, nilfs->ns_segnum, 0, nilfs);
1233                 }
1234 
1235                 segbuf->sb_sum.seg_seq = nilfs->ns_seg_seq;
1236                 nextnum = nilfs->ns_nextnum;
1237 
1238                 if (nilfs->ns_segnum == nilfs->ns_nextnum)
1239                         /* Start from the head of a new full segment */
1240                         alloc++;
1241         } else {
1242                 /* Continue logs */
1243                 prev = NILFS_LAST_SEGBUF(&sci->sc_write_logs);
1244                 nilfs_segbuf_map_cont(segbuf, prev);
1245                 segbuf->sb_sum.seg_seq = prev->sb_sum.seg_seq;
1246                 nextnum = prev->sb_nextnum;
1247 
1248                 if (segbuf->sb_rest_blocks < NILFS_PSEG_MIN_BLOCKS) {
1249                         nilfs_segbuf_map(segbuf, prev->sb_nextnum, 0, nilfs);
1250                         segbuf->sb_sum.seg_seq++;
1251                         alloc++;
1252                 }
1253         }
1254 
1255         err = nilfs_sufile_mark_dirty(nilfs->ns_sufile, segbuf->sb_segnum);
1256         if (err)
1257                 goto failed;
1258 
1259         if (alloc) {
1260                 err = nilfs_sufile_alloc(nilfs->ns_sufile, &nextnum);
1261                 if (err)
1262                         goto failed;
1263         }
1264         nilfs_segbuf_set_next_segnum(segbuf, nextnum, nilfs);
1265 
1266         BUG_ON(!list_empty(&sci->sc_segbufs));
1267         list_add_tail(&segbuf->sb_list, &sci->sc_segbufs);
1268         sci->sc_segbuf_nblocks = segbuf->sb_rest_blocks;
1269         return 0;
1270 
1271  failed:
1272         nilfs_segbuf_free(segbuf);
1273         return err;
1274 }
1275 
1276 static int nilfs_segctor_extend_segments(struct nilfs_sc_info *sci,
1277                                          struct the_nilfs *nilfs, int nadd)
1278 {
1279         struct nilfs_segment_buffer *segbuf, *prev;
1280         struct inode *sufile = nilfs->ns_sufile;
1281         __u64 nextnextnum;
1282         LIST_HEAD(list);
1283         int err, ret, i;
1284 
1285         prev = NILFS_LAST_SEGBUF(&sci->sc_segbufs);
1286         /*
1287          * Since the segment specified with nextnum might be allocated during
1288          * the previous construction, the buffer including its segusage may
1289          * not be dirty.  The following call ensures that the buffer is dirty
1290          * and will pin the buffer on memory until the sufile is written.
1291          */
1292         err = nilfs_sufile_mark_dirty(sufile, prev->sb_nextnum);
1293         if (unlikely(err))
1294                 return err;
1295 
1296         for (i = 0; i < nadd; i++) {
1297                 /* extend segment info */
1298                 err = -ENOMEM;
1299                 segbuf = nilfs_segbuf_new(sci->sc_super);
1300                 if (unlikely(!segbuf))
1301                         goto failed;
1302 
1303                 /* map this buffer to region of segment on-disk */
1304                 nilfs_segbuf_map(segbuf, prev->sb_nextnum, 0, nilfs);
1305                 sci->sc_segbuf_nblocks += segbuf->sb_rest_blocks;
1306 
1307                 /* allocate the next next full segment */
1308                 err = nilfs_sufile_alloc(sufile, &nextnextnum);
1309                 if (unlikely(err))
1310                         goto failed_segbuf;
1311 
1312                 segbuf->sb_sum.seg_seq = prev->sb_sum.seg_seq + 1;
1313                 nilfs_segbuf_set_next_segnum(segbuf, nextnextnum, nilfs);
1314 
1315                 list_add_tail(&segbuf->sb_list, &list);
1316                 prev = segbuf;
1317         }
1318         list_splice_tail(&list, &sci->sc_segbufs);
1319         return 0;
1320 
1321  failed_segbuf:
1322         nilfs_segbuf_free(segbuf);
1323  failed:
1324         list_for_each_entry(segbuf, &list, sb_list) {
1325                 ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1326                 WARN_ON(ret); /* never fails */
1327         }
1328         nilfs_destroy_logs(&list);
1329         return err;
1330 }
1331 
1332 static void nilfs_free_incomplete_logs(struct list_head *logs,
1333                                        struct the_nilfs *nilfs)
1334 {
1335         struct nilfs_segment_buffer *segbuf, *prev;
1336         struct inode *sufile = nilfs->ns_sufile;
1337         int ret;
1338 
1339         segbuf = NILFS_FIRST_SEGBUF(logs);
1340         if (nilfs->ns_nextnum != segbuf->sb_nextnum) {
1341                 ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1342                 WARN_ON(ret); /* never fails */
1343         }
1344         if (atomic_read(&segbuf->sb_err)) {
1345                 /* Case 1: The first segment failed */
1346                 if (segbuf->sb_pseg_start != segbuf->sb_fseg_start)
1347                         /* Case 1a:  Partial segment appended into an existing
1348                            segment */
1349                         nilfs_terminate_segment(nilfs, segbuf->sb_fseg_start,
1350                                                 segbuf->sb_fseg_end);
1351                 else /* Case 1b:  New full segment */
1352                         set_nilfs_discontinued(nilfs);
1353         }
1354 
1355         prev = segbuf;
1356         list_for_each_entry_continue(segbuf, logs, sb_list) {
1357                 if (prev->sb_nextnum != segbuf->sb_nextnum) {
1358                         ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1359                         WARN_ON(ret); /* never fails */
1360                 }
1361                 if (atomic_read(&segbuf->sb_err) &&
1362                     segbuf->sb_segnum != nilfs->ns_nextnum)
1363                         /* Case 2: extended segment (!= next) failed */
1364                         nilfs_sufile_set_error(sufile, segbuf->sb_segnum);
1365                 prev = segbuf;
1366         }
1367 }
1368 
1369 static void nilfs_segctor_update_segusage(struct nilfs_sc_info *sci,
1370                                           struct inode *sufile)
1371 {
1372         struct nilfs_segment_buffer *segbuf;
1373         unsigned long live_blocks;
1374         int ret;
1375 
1376         list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1377                 live_blocks = segbuf->sb_sum.nblocks +
1378                         (segbuf->sb_pseg_start - segbuf->sb_fseg_start);
1379                 ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1380                                                      live_blocks,
1381                                                      sci->sc_seg_ctime);
1382                 WARN_ON(ret); /* always succeed because the segusage is dirty */
1383         }
1384 }
1385 
1386 static void nilfs_cancel_segusage(struct list_head *logs, struct inode *sufile)
1387 {
1388         struct nilfs_segment_buffer *segbuf;
1389         int ret;
1390 
1391         segbuf = NILFS_FIRST_SEGBUF(logs);
1392         ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1393                                              segbuf->sb_pseg_start -
1394                                              segbuf->sb_fseg_start, 0);
1395         WARN_ON(ret); /* always succeed because the segusage is dirty */
1396 
1397         list_for_each_entry_continue(segbuf, logs, sb_list) {
1398                 ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1399                                                      0, 0);
1400                 WARN_ON(ret); /* always succeed */
1401         }
1402 }
1403 
1404 static void nilfs_segctor_truncate_segments(struct nilfs_sc_info *sci,
1405                                             struct nilfs_segment_buffer *last,
1406                                             struct inode *sufile)
1407 {
1408         struct nilfs_segment_buffer *segbuf = last;
1409         int ret;
1410 
1411         list_for_each_entry_continue(segbuf, &sci->sc_segbufs, sb_list) {
1412                 sci->sc_segbuf_nblocks -= segbuf->sb_rest_blocks;
1413                 ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1414                 WARN_ON(ret);
1415         }
1416         nilfs_truncate_logs(&sci->sc_segbufs, last);
1417 }
1418 
1419 
1420 static int nilfs_segctor_collect(struct nilfs_sc_info *sci,
1421                                  struct the_nilfs *nilfs, int mode)
1422 {
1423         struct nilfs_cstage prev_stage = sci->sc_stage;
1424         int err, nadd = 1;
1425 
1426         /* Collection retry loop */
1427         for (;;) {
1428                 sci->sc_nblk_this_inc = 0;
1429                 sci->sc_curseg = NILFS_FIRST_SEGBUF(&sci->sc_segbufs);
1430 
1431                 err = nilfs_segctor_reset_segment_buffer(sci);
1432                 if (unlikely(err))
1433                         goto failed;
1434 
1435                 err = nilfs_segctor_collect_blocks(sci, mode);
1436                 sci->sc_nblk_this_inc += sci->sc_curseg->sb_sum.nblocks;
1437                 if (!err)
1438                         break;
1439 
1440                 if (unlikely(err != -E2BIG))
1441                         goto failed;
1442 
1443                 /* The current segment is filled up */
1444                 if (mode != SC_LSEG_SR || sci->sc_stage.scnt < NILFS_ST_CPFILE)
1445                         break;
1446 
1447                 nilfs_clear_logs(&sci->sc_segbufs);
1448 
1449                 if (sci->sc_stage.flags & NILFS_CF_SUFREED) {
1450                         err = nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1451                                                         sci->sc_freesegs,
1452                                                         sci->sc_nfreesegs,
1453                                                         NULL);
1454                         WARN_ON(err); /* do not happen */
1455                         sci->sc_stage.flags &= ~NILFS_CF_SUFREED;
1456                 }
1457 
1458                 err = nilfs_segctor_extend_segments(sci, nilfs, nadd);
1459                 if (unlikely(err))
1460                         return err;
1461 
1462                 nadd = min_t(int, nadd << 1, SC_MAX_SEGDELTA);
1463                 sci->sc_stage = prev_stage;
1464         }
1465         nilfs_segctor_truncate_segments(sci, sci->sc_curseg, nilfs->ns_sufile);
1466         return 0;
1467 
1468  failed:
1469         return err;
1470 }
1471 
1472 static void nilfs_list_replace_buffer(struct buffer_head *old_bh,
1473                                       struct buffer_head *new_bh)
1474 {
1475         BUG_ON(!list_empty(&new_bh->b_assoc_buffers));
1476 
1477         list_replace_init(&old_bh->b_assoc_buffers, &new_bh->b_assoc_buffers);
1478         /* The caller must release old_bh */
1479 }
1480 
1481 static int
1482 nilfs_segctor_update_payload_blocknr(struct nilfs_sc_info *sci,
1483                                      struct nilfs_segment_buffer *segbuf,
1484                                      int mode)
1485 {
1486         struct inode *inode = NULL;
1487         sector_t blocknr;
1488         unsigned long nfinfo = segbuf->sb_sum.nfinfo;
1489         unsigned long nblocks = 0, ndatablk = 0;
1490         struct nilfs_sc_operations *sc_op = NULL;
1491         struct nilfs_segsum_pointer ssp;
1492         struct nilfs_finfo *finfo = NULL;
1493         union nilfs_binfo binfo;
1494         struct buffer_head *bh, *bh_org;
1495         ino_t ino = 0;
1496         int err = 0;
1497 
1498         if (!nfinfo)
1499                 goto out;
1500 
1501         blocknr = segbuf->sb_pseg_start + segbuf->sb_sum.nsumblk;
1502         ssp.bh = NILFS_SEGBUF_FIRST_BH(&segbuf->sb_segsum_buffers);
1503         ssp.offset = sizeof(struct nilfs_segment_summary);
1504 
1505         list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
1506                 if (bh == segbuf->sb_super_root)
1507                         break;
1508                 if (!finfo) {
1509                         finfo = nilfs_segctor_map_segsum_entry(
1510                                 sci, &ssp, sizeof(*finfo));
1511                         ino = le64_to_cpu(finfo->fi_ino);
1512                         nblocks = le32_to_cpu(finfo->fi_nblocks);
1513                         ndatablk = le32_to_cpu(finfo->fi_ndatablk);
1514 
1515                         inode = bh->b_page->mapping->host;
1516 
1517                         if (mode == SC_LSEG_DSYNC)
1518                                 sc_op = &nilfs_sc_dsync_ops;
1519                         else if (ino == NILFS_DAT_INO)
1520                                 sc_op = &nilfs_sc_dat_ops;
1521                         else /* file blocks */
1522                                 sc_op = &nilfs_sc_file_ops;
1523                 }
1524                 bh_org = bh;
1525                 get_bh(bh_org);
1526                 err = nilfs_bmap_assign(NILFS_I(inode)->i_bmap, &bh, blocknr,
1527                                         &binfo);
1528                 if (bh != bh_org)
1529                         nilfs_list_replace_buffer(bh_org, bh);
1530                 brelse(bh_org);
1531                 if (unlikely(err))
1532                         goto failed_bmap;
1533 
1534                 if (ndatablk > 0)
1535                         sc_op->write_data_binfo(sci, &ssp, &binfo);
1536                 else
1537                         sc_op->write_node_binfo(sci, &ssp, &binfo);
1538 
1539                 blocknr++;
1540                 if (--nblocks == 0) {
1541                         finfo = NULL;
1542                         if (--nfinfo == 0)
1543                                 break;
1544                 } else if (ndatablk > 0)
1545                         ndatablk--;
1546         }
1547  out:
1548         return 0;
1549 
1550  failed_bmap:
1551         return err;
1552 }
1553 
1554 static int nilfs_segctor_assign(struct nilfs_sc_info *sci, int mode)
1555 {
1556         struct nilfs_segment_buffer *segbuf;
1557         int err;
1558 
1559         list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1560                 err = nilfs_segctor_update_payload_blocknr(sci, segbuf, mode);
1561                 if (unlikely(err))
1562                         return err;
1563                 nilfs_segbuf_fill_in_segsum(segbuf);
1564         }
1565         return 0;
1566 }
1567 
1568 static void nilfs_begin_page_io(struct page *page)
1569 {
1570         if (!page || PageWriteback(page))
1571                 /* For split b-tree node pages, this function may be called
1572                    twice.  We ignore the 2nd or later calls by this check. */
1573                 return;
1574 
1575         lock_page(page);
1576         clear_page_dirty_for_io(page);
1577         set_page_writeback(page);
1578         unlock_page(page);
1579 }
1580 
1581 static void nilfs_segctor_prepare_write(struct nilfs_sc_info *sci)
1582 {
1583         struct nilfs_segment_buffer *segbuf;
1584         struct page *bd_page = NULL, *fs_page = NULL;
1585 
1586         list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1587                 struct buffer_head *bh;
1588 
1589                 list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1590                                     b_assoc_buffers) {
1591                         set_buffer_async_write(bh);
1592                         if (bh->b_page != bd_page) {
1593                                 if (bd_page) {
1594                                         lock_page(bd_page);
1595                                         clear_page_dirty_for_io(bd_page);
1596                                         set_page_writeback(bd_page);
1597                                         unlock_page(bd_page);
1598                                 }
1599                                 bd_page = bh->b_page;
1600                         }
1601                 }
1602 
1603                 list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1604                                     b_assoc_buffers) {
1605                         set_buffer_async_write(bh);
1606                         if (bh == segbuf->sb_super_root) {
1607                                 if (bh->b_page != bd_page) {
1608                                         lock_page(bd_page);
1609                                         clear_page_dirty_for_io(bd_page);
1610                                         set_page_writeback(bd_page);
1611                                         unlock_page(bd_page);
1612                                         bd_page = bh->b_page;
1613                                 }
1614                                 break;
1615                         }
1616                         if (bh->b_page != fs_page) {
1617                                 nilfs_begin_page_io(fs_page);
1618                                 fs_page = bh->b_page;
1619                         }
1620                 }
1621         }
1622         if (bd_page) {
1623                 lock_page(bd_page);
1624                 clear_page_dirty_for_io(bd_page);
1625                 set_page_writeback(bd_page);
1626                 unlock_page(bd_page);
1627         }
1628         nilfs_begin_page_io(fs_page);
1629 }
1630 
1631 static int nilfs_segctor_write(struct nilfs_sc_info *sci,
1632                                struct the_nilfs *nilfs)
1633 {
1634         int ret;
1635 
1636         ret = nilfs_write_logs(&sci->sc_segbufs, nilfs);
1637         list_splice_tail_init(&sci->sc_segbufs, &sci->sc_write_logs);
1638         return ret;
1639 }
1640 
1641 static void nilfs_end_page_io(struct page *page, int err)
1642 {
1643         if (!page)
1644                 return;
1645 
1646         if (buffer_nilfs_node(page_buffers(page)) && !PageWriteback(page)) {
1647                 /*
1648                  * For b-tree node pages, this function may be called twice
1649                  * or more because they might be split in a segment.
1650                  */
1651                 if (PageDirty(page)) {
1652                         /*
1653                          * For pages holding split b-tree node buffers, dirty
1654                          * flag on the buffers may be cleared discretely.
1655                          * In that case, the page is once redirtied for
1656                          * remaining buffers, and it must be cancelled if
1657                          * all the buffers get cleaned later.
1658                          */
1659                         lock_page(page);
1660                         if (nilfs_page_buffers_clean(page))
1661                                 __nilfs_clear_page_dirty(page);
1662                         unlock_page(page);
1663                 }
1664                 return;
1665         }
1666 
1667         if (!err) {
1668                 if (!nilfs_page_buffers_clean(page))
1669                         __set_page_dirty_nobuffers(page);
1670                 ClearPageError(page);
1671         } else {
1672                 __set_page_dirty_nobuffers(page);
1673                 SetPageError(page);
1674         }
1675 
1676         end_page_writeback(page);
1677 }
1678 
1679 static void nilfs_abort_logs(struct list_head *logs, int err)
1680 {
1681         struct nilfs_segment_buffer *segbuf;
1682         struct page *bd_page = NULL, *fs_page = NULL;
1683         struct buffer_head *bh;
1684 
1685         if (list_empty(logs))
1686                 return;
1687 
1688         list_for_each_entry(segbuf, logs, sb_list) {
1689                 list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1690                                     b_assoc_buffers) {
1691                         clear_buffer_async_write(bh);
1692                         if (bh->b_page != bd_page) {
1693                                 if (bd_page)
1694                                         end_page_writeback(bd_page);
1695                                 bd_page = bh->b_page;
1696                         }
1697                 }
1698 
1699                 list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1700                                     b_assoc_buffers) {
1701                         clear_buffer_async_write(bh);
1702                         if (bh == segbuf->sb_super_root) {
1703                                 if (bh->b_page != bd_page) {
1704                                         end_page_writeback(bd_page);
1705                                         bd_page = bh->b_page;
1706                                 }
1707                                 break;
1708                         }
1709                         if (bh->b_page != fs_page) {
1710                                 nilfs_end_page_io(fs_page, err);
1711                                 fs_page = bh->b_page;
1712                         }
1713                 }
1714         }
1715         if (bd_page)
1716                 end_page_writeback(bd_page);
1717 
1718         nilfs_end_page_io(fs_page, err);
1719 }
1720 
1721 static void nilfs_segctor_abort_construction(struct nilfs_sc_info *sci,
1722                                              struct the_nilfs *nilfs, int err)
1723 {
1724         LIST_HEAD(logs);
1725         int ret;
1726 
1727         list_splice_tail_init(&sci->sc_write_logs, &logs);
1728         ret = nilfs_wait_on_logs(&logs);
1729         nilfs_abort_logs(&logs, ret ? : err);
1730 
1731         list_splice_tail_init(&sci->sc_segbufs, &logs);
1732         nilfs_cancel_segusage(&logs, nilfs->ns_sufile);
1733         nilfs_free_incomplete_logs(&logs, nilfs);
1734 
1735         if (sci->sc_stage.flags & NILFS_CF_SUFREED) {
1736                 ret = nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1737                                                 sci->sc_freesegs,
1738                                                 sci->sc_nfreesegs,
1739                                                 NULL);
1740                 WARN_ON(ret); /* do not happen */
1741         }
1742 
1743         nilfs_destroy_logs(&logs);
1744 }
1745 
1746 static void nilfs_set_next_segment(struct the_nilfs *nilfs,
1747                                    struct nilfs_segment_buffer *segbuf)
1748 {
1749         nilfs->ns_segnum = segbuf->sb_segnum;
1750         nilfs->ns_nextnum = segbuf->sb_nextnum;
1751         nilfs->ns_pseg_offset = segbuf->sb_pseg_start - segbuf->sb_fseg_start
1752                 + segbuf->sb_sum.nblocks;
1753         nilfs->ns_seg_seq = segbuf->sb_sum.seg_seq;
1754         nilfs->ns_ctime = segbuf->sb_sum.ctime;
1755 }
1756 
1757 static void nilfs_segctor_complete_write(struct nilfs_sc_info *sci)
1758 {
1759         struct nilfs_segment_buffer *segbuf;
1760         struct page *bd_page = NULL, *fs_page = NULL;
1761         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
1762         int update_sr = false;
1763 
1764         list_for_each_entry(segbuf, &sci->sc_write_logs, sb_list) {
1765                 struct buffer_head *bh;
1766 
1767                 list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1768                                     b_assoc_buffers) {
1769                         set_buffer_uptodate(bh);
1770                         clear_buffer_dirty(bh);
1771                         clear_buffer_async_write(bh);
1772                         if (bh->b_page != bd_page) {
1773                                 if (bd_page)
1774                                         end_page_writeback(bd_page);
1775                                 bd_page = bh->b_page;
1776                         }
1777                 }
1778                 /*
1779                  * We assume that the buffers which belong to the same page
1780                  * continue over the buffer list.
1781                  * Under this assumption, the last BHs of pages is
1782                  * identifiable by the discontinuity of bh->b_page
1783                  * (page != fs_page).
1784                  *
1785                  * For B-tree node blocks, however, this assumption is not
1786                  * guaranteed.  The cleanup code of B-tree node pages needs
1787                  * special care.
1788                  */
1789                 list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1790                                     b_assoc_buffers) {
1791                         set_buffer_uptodate(bh);
1792                         clear_buffer_dirty(bh);
1793                         clear_buffer_async_write(bh);
1794                         clear_buffer_delay(bh);
1795                         clear_buffer_nilfs_volatile(bh);
1796                         clear_buffer_nilfs_redirected(bh);
1797                         if (bh == segbuf->sb_super_root) {
1798                                 if (bh->b_page != bd_page) {
1799                                         end_page_writeback(bd_page);
1800                                         bd_page = bh->b_page;
1801                                 }
1802                                 update_sr = true;
1803                                 break;
1804                         }
1805                         if (bh->b_page != fs_page) {
1806                                 nilfs_end_page_io(fs_page, 0);
1807                                 fs_page = bh->b_page;
1808                         }
1809                 }
1810 
1811                 if (!nilfs_segbuf_simplex(segbuf)) {
1812                         if (segbuf->sb_sum.flags & NILFS_SS_LOGBGN) {
1813                                 set_bit(NILFS_SC_UNCLOSED, &sci->sc_flags);
1814                                 sci->sc_lseg_stime = jiffies;
1815                         }
1816                         if (segbuf->sb_sum.flags & NILFS_SS_LOGEND)
1817                                 clear_bit(NILFS_SC_UNCLOSED, &sci->sc_flags);
1818                 }
1819         }
1820         /*
1821          * Since pages may continue over multiple segment buffers,
1822          * end of the last page must be checked outside of the loop.
1823          */
1824         if (bd_page)
1825                 end_page_writeback(bd_page);
1826 
1827         nilfs_end_page_io(fs_page, 0);
1828 
1829         nilfs_drop_collected_inodes(&sci->sc_dirty_files);
1830 
1831         if (nilfs_doing_gc())
1832                 nilfs_drop_collected_inodes(&sci->sc_gc_inodes);
1833         else
1834                 nilfs->ns_nongc_ctime = sci->sc_seg_ctime;
1835 
1836         sci->sc_nblk_inc += sci->sc_nblk_this_inc;
1837 
1838         segbuf = NILFS_LAST_SEGBUF(&sci->sc_write_logs);
1839         nilfs_set_next_segment(nilfs, segbuf);
1840 
1841         if (update_sr) {
1842                 nilfs->ns_flushed_device = 0;
1843                 nilfs_set_last_segment(nilfs, segbuf->sb_pseg_start,
1844                                        segbuf->sb_sum.seg_seq, nilfs->ns_cno++);
1845 
1846                 clear_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
1847                 clear_bit(NILFS_SC_DIRTY, &sci->sc_flags);
1848                 set_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags);
1849                 nilfs_segctor_clear_metadata_dirty(sci);
1850         } else
1851                 clear_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags);
1852 }
1853 
1854 static int nilfs_segctor_wait(struct nilfs_sc_info *sci)
1855 {
1856         int ret;
1857 
1858         ret = nilfs_wait_on_logs(&sci->sc_write_logs);
1859         if (!ret) {
1860                 nilfs_segctor_complete_write(sci);
1861                 nilfs_destroy_logs(&sci->sc_write_logs);
1862         }
1863         return ret;
1864 }
1865 
1866 static int nilfs_segctor_collect_dirty_files(struct nilfs_sc_info *sci,
1867                                              struct the_nilfs *nilfs)
1868 {
1869         struct nilfs_inode_info *ii, *n;
1870         struct inode *ifile = sci->sc_root->ifile;
1871 
1872         spin_lock(&nilfs->ns_inode_lock);
1873  retry:
1874         list_for_each_entry_safe(ii, n, &nilfs->ns_dirty_files, i_dirty) {
1875                 if (!ii->i_bh) {
1876                         struct buffer_head *ibh;
1877                         int err;
1878 
1879                         spin_unlock(&nilfs->ns_inode_lock);
1880                         err = nilfs_ifile_get_inode_block(
1881                                 ifile, ii->vfs_inode.i_ino, &ibh);
1882                         if (unlikely(err)) {
1883                                 nilfs_warning(sci->sc_super, __func__,
1884                                               "failed to get inode block.\n");
1885                                 return err;
1886                         }
1887                         mark_buffer_dirty(ibh);
1888                         nilfs_mdt_mark_dirty(ifile);
1889                         spin_lock(&nilfs->ns_inode_lock);
1890                         if (likely(!ii->i_bh))
1891                                 ii->i_bh = ibh;
1892                         else
1893                                 brelse(ibh);
1894                         goto retry;
1895                 }
1896 
1897                 clear_bit(NILFS_I_QUEUED, &ii->i_state);
1898                 set_bit(NILFS_I_BUSY, &ii->i_state);
1899                 list_move_tail(&ii->i_dirty, &sci->sc_dirty_files);
1900         }
1901         spin_unlock(&nilfs->ns_inode_lock);
1902 
1903         return 0;
1904 }
1905 
1906 static void nilfs_segctor_drop_written_files(struct nilfs_sc_info *sci,
1907                                              struct the_nilfs *nilfs)
1908 {
1909         struct nilfs_inode_info *ii, *n;
1910         int during_mount = !(sci->sc_super->s_flags & MS_ACTIVE);
1911         int defer_iput = false;
1912 
1913         spin_lock(&nilfs->ns_inode_lock);
1914         list_for_each_entry_safe(ii, n, &sci->sc_dirty_files, i_dirty) {
1915                 if (!test_and_clear_bit(NILFS_I_UPDATED, &ii->i_state) ||
1916                     test_bit(NILFS_I_DIRTY, &ii->i_state))
1917                         continue;
1918 
1919                 clear_bit(NILFS_I_BUSY, &ii->i_state);
1920                 brelse(ii->i_bh);
1921                 ii->i_bh = NULL;
1922                 list_del_init(&ii->i_dirty);
1923                 if (!ii->vfs_inode.i_nlink || during_mount) {
1924                         /*
1925                          * Defer calling iput() to avoid deadlocks if
1926                          * i_nlink == 0 or mount is not yet finished.
1927                          */
1928                         list_add_tail(&ii->i_dirty, &sci->sc_iput_queue);
1929                         defer_iput = true;
1930                 } else {
1931                         spin_unlock(&nilfs->ns_inode_lock);
1932                         iput(&ii->vfs_inode);
1933                         spin_lock(&nilfs->ns_inode_lock);
1934                 }
1935         }
1936         spin_unlock(&nilfs->ns_inode_lock);
1937 
1938         if (defer_iput)
1939                 schedule_work(&sci->sc_iput_work);
1940 }
1941 
1942 /*
1943  * Main procedure of segment constructor
1944  */
1945 static int nilfs_segctor_do_construct(struct nilfs_sc_info *sci, int mode)
1946 {
1947         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
1948         int err;
1949 
1950         sci->sc_stage.scnt = NILFS_ST_INIT;
1951         sci->sc_cno = nilfs->ns_cno;
1952 
1953         err = nilfs_segctor_collect_dirty_files(sci, nilfs);
1954         if (unlikely(err))
1955                 goto out;
1956 
1957         if (nilfs_test_metadata_dirty(nilfs, sci->sc_root))
1958                 set_bit(NILFS_SC_DIRTY, &sci->sc_flags);
1959 
1960         if (nilfs_segctor_clean(sci))
1961                 goto out;
1962 
1963         do {
1964                 sci->sc_stage.flags &= ~NILFS_CF_HISTORY_MASK;
1965 
1966                 err = nilfs_segctor_begin_construction(sci, nilfs);
1967                 if (unlikely(err))
1968                         goto out;
1969 
1970                 /* Update time stamp */
1971                 sci->sc_seg_ctime = get_seconds();
1972 
1973                 err = nilfs_segctor_collect(sci, nilfs, mode);
1974                 if (unlikely(err))
1975                         goto failed;
1976 
1977                 /* Avoid empty segment */
1978                 if (sci->sc_stage.scnt == NILFS_ST_DONE &&
1979                     nilfs_segbuf_empty(sci->sc_curseg)) {
1980                         nilfs_segctor_abort_construction(sci, nilfs, 1);
1981                         goto out;
1982                 }
1983 
1984                 err = nilfs_segctor_assign(sci, mode);
1985                 if (unlikely(err))
1986                         goto failed;
1987 
1988                 if (sci->sc_stage.flags & NILFS_CF_IFILE_STARTED)
1989                         nilfs_segctor_fill_in_file_bmap(sci);
1990 
1991                 if (mode == SC_LSEG_SR &&
1992                     sci->sc_stage.scnt >= NILFS_ST_CPFILE) {
1993                         err = nilfs_segctor_fill_in_checkpoint(sci);
1994                         if (unlikely(err))
1995                                 goto failed_to_write;
1996 
1997                         nilfs_segctor_fill_in_super_root(sci, nilfs);
1998                 }
1999                 nilfs_segctor_update_segusage(sci, nilfs->ns_sufile);
2000 
2001                 /* Write partial segments */
2002                 nilfs_segctor_prepare_write(sci);
2003 
2004                 nilfs_add_checksums_on_logs(&sci->sc_segbufs,
2005                                             nilfs->ns_crc_seed);
2006 
2007                 err = nilfs_segctor_write(sci, nilfs);
2008                 if (unlikely(err))
2009                         goto failed_to_write;
2010 
2011                 if (sci->sc_stage.scnt == NILFS_ST_DONE ||
2012                     nilfs->ns_blocksize_bits != PAGE_CACHE_SHIFT) {
2013                         /*
2014                          * At this point, we avoid double buffering
2015                          * for blocksize < pagesize because page dirty
2016                          * flag is turned off during write and dirty
2017                          * buffers are not properly collected for
2018                          * pages crossing over segments.
2019                          */
2020                         err = nilfs_segctor_wait(sci);
2021                         if (err)
2022                                 goto failed_to_write;
2023                 }
2024         } while (sci->sc_stage.scnt != NILFS_ST_DONE);
2025 
2026  out:
2027         nilfs_segctor_drop_written_files(sci, nilfs);
2028         return err;
2029 
2030  failed_to_write:
2031         if (sci->sc_stage.flags & NILFS_CF_IFILE_STARTED)
2032                 nilfs_redirty_inodes(&sci->sc_dirty_files);
2033 
2034  failed:
2035         if (nilfs_doing_gc())
2036                 nilfs_redirty_inodes(&sci->sc_gc_inodes);
2037         nilfs_segctor_abort_construction(sci, nilfs, err);
2038         goto out;
2039 }
2040 
2041 /**
2042  * nilfs_segctor_start_timer - set timer of background write
2043  * @sci: nilfs_sc_info
2044  *
2045  * If the timer has already been set, it ignores the new request.
2046  * This function MUST be called within a section locking the segment
2047  * semaphore.
2048  */
2049 static void nilfs_segctor_start_timer(struct nilfs_sc_info *sci)
2050 {
2051         spin_lock(&sci->sc_state_lock);
2052         if (!(sci->sc_state & NILFS_SEGCTOR_COMMIT)) {
2053                 sci->sc_timer.expires = jiffies + sci->sc_interval;
2054                 add_timer(&sci->sc_timer);
2055                 sci->sc_state |= NILFS_SEGCTOR_COMMIT;
2056         }
2057         spin_unlock(&sci->sc_state_lock);
2058 }
2059 
2060 static void nilfs_segctor_do_flush(struct nilfs_sc_info *sci, int bn)
2061 {
2062         spin_lock(&sci->sc_state_lock);
2063         if (!(sci->sc_flush_request & (1 << bn))) {
2064                 unsigned long prev_req = sci->sc_flush_request;
2065 
2066                 sci->sc_flush_request |= (1 << bn);
2067                 if (!prev_req)
2068                         wake_up(&sci->sc_wait_daemon);
2069         }
2070         spin_unlock(&sci->sc_state_lock);
2071 }
2072 
2073 /**
2074  * nilfs_flush_segment - trigger a segment construction for resource control
2075  * @sb: super block
2076  * @ino: inode number of the file to be flushed out.
2077  */
2078 void nilfs_flush_segment(struct super_block *sb, ino_t ino)
2079 {
2080         struct the_nilfs *nilfs = sb->s_fs_info;
2081         struct nilfs_sc_info *sci = nilfs->ns_writer;
2082 
2083         if (!sci || nilfs_doing_construction())
2084                 return;
2085         nilfs_segctor_do_flush(sci, NILFS_MDT_INODE(sb, ino) ? ino : 0);
2086                                         /* assign bit 0 to data files */
2087 }
2088 
2089 struct nilfs_segctor_wait_request {
2090         wait_queue_t    wq;
2091         __u32           seq;
2092         int             err;
2093         atomic_t        done;
2094 };
2095 
2096 static int nilfs_segctor_sync(struct nilfs_sc_info *sci)
2097 {
2098         struct nilfs_segctor_wait_request wait_req;
2099         int err = 0;
2100 
2101         spin_lock(&sci->sc_state_lock);
2102         init_wait(&wait_req.wq);
2103         wait_req.err = 0;
2104         atomic_set(&wait_req.done, 0);
2105         wait_req.seq = ++sci->sc_seq_request;
2106         spin_unlock(&sci->sc_state_lock);
2107 
2108         init_waitqueue_entry(&wait_req.wq, current);
2109         add_wait_queue(&sci->sc_wait_request, &wait_req.wq);
2110         set_current_state(TASK_INTERRUPTIBLE);
2111         wake_up(&sci->sc_wait_daemon);
2112 
2113         for (;;) {
2114                 if (atomic_read(&wait_req.done)) {
2115                         err = wait_req.err;
2116                         break;
2117                 }
2118                 if (!signal_pending(current)) {
2119                         schedule();
2120                         continue;
2121                 }
2122                 err = -ERESTARTSYS;
2123                 break;
2124         }
2125         finish_wait(&sci->sc_wait_request, &wait_req.wq);
2126         return err;
2127 }
2128 
2129 static void nilfs_segctor_wakeup(struct nilfs_sc_info *sci, int err)
2130 {
2131         struct nilfs_segctor_wait_request *wrq, *n;
2132         unsigned long flags;
2133 
2134         spin_lock_irqsave(&sci->sc_wait_request.lock, flags);
2135         list_for_each_entry_safe(wrq, n, &sci->sc_wait_request.task_list,
2136                                  wq.task_list) {
2137                 if (!atomic_read(&wrq->done) &&
2138                     nilfs_cnt32_ge(sci->sc_seq_done, wrq->seq)) {
2139                         wrq->err = err;
2140                         atomic_set(&wrq->done, 1);
2141                 }
2142                 if (atomic_read(&wrq->done)) {
2143                         wrq->wq.func(&wrq->wq,
2144                                      TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
2145                                      0, NULL);
2146                 }
2147         }
2148         spin_unlock_irqrestore(&sci->sc_wait_request.lock, flags);
2149 }
2150 
2151 /**
2152  * nilfs_construct_segment - construct a logical segment
2153  * @sb: super block
2154  *
2155  * Return Value: On success, 0 is retured. On errors, one of the following
2156  * negative error code is returned.
2157  *
2158  * %-EROFS - Read only filesystem.
2159  *
2160  * %-EIO - I/O error
2161  *
2162  * %-ENOSPC - No space left on device (only in a panic state).
2163  *
2164  * %-ERESTARTSYS - Interrupted.
2165  *
2166  * %-ENOMEM - Insufficient memory available.
2167  */
2168 int nilfs_construct_segment(struct super_block *sb)
2169 {
2170         struct the_nilfs *nilfs = sb->s_fs_info;
2171         struct nilfs_sc_info *sci = nilfs->ns_writer;
2172         struct nilfs_transaction_info *ti;
2173         int err;
2174 
2175         if (!sci)
2176                 return -EROFS;
2177 
2178         /* A call inside transactions causes a deadlock. */
2179         BUG_ON((ti = current->journal_info) && ti->ti_magic == NILFS_TI_MAGIC);
2180 
2181         err = nilfs_segctor_sync(sci);
2182         return err;
2183 }
2184 
2185 /**
2186  * nilfs_construct_dsync_segment - construct a data-only logical segment
2187  * @sb: super block
2188  * @inode: inode whose data blocks should be written out
2189  * @start: start byte offset
2190  * @end: end byte offset (inclusive)
2191  *
2192  * Return Value: On success, 0 is retured. On errors, one of the following
2193  * negative error code is returned.
2194  *
2195  * %-EROFS - Read only filesystem.
2196  *
2197  * %-EIO - I/O error
2198  *
2199  * %-ENOSPC - No space left on device (only in a panic state).
2200  *
2201  * %-ERESTARTSYS - Interrupted.
2202  *
2203  * %-ENOMEM - Insufficient memory available.
2204  */
2205 int nilfs_construct_dsync_segment(struct super_block *sb, struct inode *inode,
2206                                   loff_t start, loff_t end)
2207 {
2208         struct the_nilfs *nilfs = sb->s_fs_info;
2209         struct nilfs_sc_info *sci = nilfs->ns_writer;
2210         struct nilfs_inode_info *ii;
2211         struct nilfs_transaction_info ti;
2212         int err = 0;
2213 
2214         if (!sci)
2215                 return -EROFS;
2216 
2217         nilfs_transaction_lock(sb, &ti, 0);
2218 
2219         ii = NILFS_I(inode);
2220         if (test_bit(NILFS_I_INODE_DIRTY, &ii->i_state) ||
2221             nilfs_test_opt(nilfs, STRICT_ORDER) ||
2222             test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags) ||
2223             nilfs_discontinued(nilfs)) {
2224                 nilfs_transaction_unlock(sb);
2225                 err = nilfs_segctor_sync(sci);
2226                 return err;
2227         }
2228 
2229         spin_lock(&nilfs->ns_inode_lock);
2230         if (!test_bit(NILFS_I_QUEUED, &ii->i_state) &&
2231             !test_bit(NILFS_I_BUSY, &ii->i_state)) {
2232                 spin_unlock(&nilfs->ns_inode_lock);
2233                 nilfs_transaction_unlock(sb);
2234                 return 0;
2235         }
2236         spin_unlock(&nilfs->ns_inode_lock);
2237         sci->sc_dsync_inode = ii;
2238         sci->sc_dsync_start = start;
2239         sci->sc_dsync_end = end;
2240 
2241         err = nilfs_segctor_do_construct(sci, SC_LSEG_DSYNC);
2242         if (!err)
2243                 nilfs->ns_flushed_device = 0;
2244 
2245         nilfs_transaction_unlock(sb);
2246         return err;
2247 }
2248 
2249 #define FLUSH_FILE_BIT  (0x1) /* data file only */
2250 #define FLUSH_DAT_BIT   (1 << NILFS_DAT_INO) /* DAT only */
2251 
2252 /**
2253  * nilfs_segctor_accept - record accepted sequence count of log-write requests
2254  * @sci: segment constructor object
2255  */
2256 static void nilfs_segctor_accept(struct nilfs_sc_info *sci)
2257 {
2258         spin_lock(&sci->sc_state_lock);
2259         sci->sc_seq_accepted = sci->sc_seq_request;
2260         spin_unlock(&sci->sc_state_lock);
2261         del_timer_sync(&sci->sc_timer);
2262 }
2263 
2264 /**
2265  * nilfs_segctor_notify - notify the result of request to caller threads
2266  * @sci: segment constructor object
2267  * @mode: mode of log forming
2268  * @err: error code to be notified
2269  */
2270 static void nilfs_segctor_notify(struct nilfs_sc_info *sci, int mode, int err)
2271 {
2272         /* Clear requests (even when the construction failed) */
2273         spin_lock(&sci->sc_state_lock);
2274 
2275         if (mode == SC_LSEG_SR) {
2276                 sci->sc_state &= ~NILFS_SEGCTOR_COMMIT;
2277                 sci->sc_seq_done = sci->sc_seq_accepted;
2278                 nilfs_segctor_wakeup(sci, err);
2279                 sci->sc_flush_request = 0;
2280         } else {
2281                 if (mode == SC_FLUSH_FILE)
2282                         sci->sc_flush_request &= ~FLUSH_FILE_BIT;
2283                 else if (mode == SC_FLUSH_DAT)
2284                         sci->sc_flush_request &= ~FLUSH_DAT_BIT;
2285 
2286                 /* re-enable timer if checkpoint creation was not done */
2287                 if ((sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
2288                     time_before(jiffies, sci->sc_timer.expires))
2289                         add_timer(&sci->sc_timer);
2290         }
2291         spin_unlock(&sci->sc_state_lock);
2292 }
2293 
2294 /**
2295  * nilfs_segctor_construct - form logs and write them to disk
2296  * @sci: segment constructor object
2297  * @mode: mode of log forming
2298  */
2299 static int nilfs_segctor_construct(struct nilfs_sc_info *sci, int mode)
2300 {
2301         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2302         struct nilfs_super_block **sbp;
2303         int err = 0;
2304 
2305         nilfs_segctor_accept(sci);
2306 
2307         if (nilfs_discontinued(nilfs))
2308                 mode = SC_LSEG_SR;
2309         if (!nilfs_segctor_confirm(sci))
2310                 err = nilfs_segctor_do_construct(sci, mode);
2311 
2312         if (likely(!err)) {
2313                 if (mode != SC_FLUSH_DAT)
2314                         atomic_set(&nilfs->ns_ndirtyblks, 0);
2315                 if (test_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags) &&
2316                     nilfs_discontinued(nilfs)) {
2317                         down_write(&nilfs->ns_sem);
2318                         err = -EIO;
2319                         sbp = nilfs_prepare_super(sci->sc_super,
2320                                                   nilfs_sb_will_flip(nilfs));
2321                         if (likely(sbp)) {
2322                                 nilfs_set_log_cursor(sbp[0], nilfs);
2323                                 err = nilfs_commit_super(sci->sc_super,
2324                                                          NILFS_SB_COMMIT);
2325                         }
2326                         up_write(&nilfs->ns_sem);
2327                 }
2328         }
2329 
2330         nilfs_segctor_notify(sci, mode, err);
2331         return err;
2332 }
2333 
2334 static void nilfs_construction_timeout(unsigned long data)
2335 {
2336         struct task_struct *p = (struct task_struct *)data;
2337         wake_up_process(p);
2338 }
2339 
2340 static void
2341 nilfs_remove_written_gcinodes(struct the_nilfs *nilfs, struct list_head *head)
2342 {
2343         struct nilfs_inode_info *ii, *n;
2344 
2345         list_for_each_entry_safe(ii, n, head, i_dirty) {
2346                 if (!test_bit(NILFS_I_UPDATED, &ii->i_state))
2347                         continue;
2348                 list_del_init(&ii->i_dirty);
2349                 truncate_inode_pages(&ii->vfs_inode.i_data, 0);
2350                 nilfs_btnode_cache_clear(&ii->i_btnode_cache);
2351                 iput(&ii->vfs_inode);
2352         }
2353 }
2354 
2355 int nilfs_clean_segments(struct super_block *sb, struct nilfs_argv *argv,
2356                          void **kbufs)
2357 {
2358         struct the_nilfs *nilfs = sb->s_fs_info;
2359         struct nilfs_sc_info *sci = nilfs->ns_writer;
2360         struct nilfs_transaction_info ti;
2361         int err;
2362 
2363         if (unlikely(!sci))
2364                 return -EROFS;
2365 
2366         nilfs_transaction_lock(sb, &ti, 1);
2367 
2368         err = nilfs_mdt_save_to_shadow_map(nilfs->ns_dat);
2369         if (unlikely(err))
2370                 goto out_unlock;
2371 
2372         err = nilfs_ioctl_prepare_clean_segments(nilfs, argv, kbufs);
2373         if (unlikely(err)) {
2374                 nilfs_mdt_restore_from_shadow_map(nilfs->ns_dat);
2375                 goto out_unlock;
2376         }
2377 
2378         sci->sc_freesegs = kbufs[4];
2379         sci->sc_nfreesegs = argv[4].v_nmembs;
2380         list_splice_tail_init(&nilfs->ns_gc_inodes, &sci->sc_gc_inodes);
2381 
2382         for (;;) {
2383                 err = nilfs_segctor_construct(sci, SC_LSEG_SR);
2384                 nilfs_remove_written_gcinodes(nilfs, &sci->sc_gc_inodes);
2385 
2386                 if (likely(!err))
2387                         break;
2388 
2389                 nilfs_warning(sb, __func__,
2390                               "segment construction failed. (err=%d)", err);
2391                 set_current_state(TASK_INTERRUPTIBLE);
2392                 schedule_timeout(sci->sc_interval);
2393         }
2394         if (nilfs_test_opt(nilfs, DISCARD)) {
2395                 int ret = nilfs_discard_segments(nilfs, sci->sc_freesegs,
2396                                                  sci->sc_nfreesegs);
2397                 if (ret) {
2398                         printk(KERN_WARNING
2399                                "NILFS warning: error %d on discard request, "
2400                                "turning discards off for the device\n", ret);
2401                         nilfs_clear_opt(nilfs, DISCARD);
2402                 }
2403         }
2404 
2405  out_unlock:
2406         sci->sc_freesegs = NULL;
2407         sci->sc_nfreesegs = 0;
2408         nilfs_mdt_clear_shadow_map(nilfs->ns_dat);
2409         nilfs_transaction_unlock(sb);
2410         return err;
2411 }
2412 
2413 static void nilfs_segctor_thread_construct(struct nilfs_sc_info *sci, int mode)
2414 {
2415         struct nilfs_transaction_info ti;
2416 
2417         nilfs_transaction_lock(sci->sc_super, &ti, 0);
2418         nilfs_segctor_construct(sci, mode);
2419 
2420         /*
2421          * Unclosed segment should be retried.  We do this using sc_timer.
2422          * Timeout of sc_timer will invoke complete construction which leads
2423          * to close the current logical segment.
2424          */
2425         if (test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags))
2426                 nilfs_segctor_start_timer(sci);
2427 
2428         nilfs_transaction_unlock(sci->sc_super);
2429 }
2430 
2431 static void nilfs_segctor_do_immediate_flush(struct nilfs_sc_info *sci)
2432 {
2433         int mode = 0;
2434         int err;
2435 
2436         spin_lock(&sci->sc_state_lock);
2437         mode = (sci->sc_flush_request & FLUSH_DAT_BIT) ?
2438                 SC_FLUSH_DAT : SC_FLUSH_FILE;
2439         spin_unlock(&sci->sc_state_lock);
2440 
2441         if (mode) {
2442                 err = nilfs_segctor_do_construct(sci, mode);
2443 
2444                 spin_lock(&sci->sc_state_lock);
2445                 sci->sc_flush_request &= (mode == SC_FLUSH_FILE) ?
2446                         ~FLUSH_FILE_BIT : ~FLUSH_DAT_BIT;
2447                 spin_unlock(&sci->sc_state_lock);
2448         }
2449         clear_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags);
2450 }
2451 
2452 static int nilfs_segctor_flush_mode(struct nilfs_sc_info *sci)
2453 {
2454         if (!test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags) ||
2455             time_before(jiffies, sci->sc_lseg_stime + sci->sc_mjcp_freq)) {
2456                 if (!(sci->sc_flush_request & ~FLUSH_FILE_BIT))
2457                         return SC_FLUSH_FILE;
2458                 else if (!(sci->sc_flush_request & ~FLUSH_DAT_BIT))
2459                         return SC_FLUSH_DAT;
2460         }
2461         return SC_LSEG_SR;
2462 }
2463 
2464 /**
2465  * nilfs_segctor_thread - main loop of the segment constructor thread.
2466  * @arg: pointer to a struct nilfs_sc_info.
2467  *
2468  * nilfs_segctor_thread() initializes a timer and serves as a daemon
2469  * to execute segment constructions.
2470  */
2471 static int nilfs_segctor_thread(void *arg)
2472 {
2473         struct nilfs_sc_info *sci = (struct nilfs_sc_info *)arg;
2474         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2475         int timeout = 0;
2476 
2477         sci->sc_timer.data = (unsigned long)current;
2478         sci->sc_timer.function = nilfs_construction_timeout;
2479 
2480         /* start sync. */
2481         sci->sc_task = current;
2482         wake_up(&sci->sc_wait_task); /* for nilfs_segctor_start_thread() */
2483         printk(KERN_INFO
2484                "segctord starting. Construction interval = %lu seconds, "
2485                "CP frequency < %lu seconds\n",
2486                sci->sc_interval / HZ, sci->sc_mjcp_freq / HZ);
2487 
2488         spin_lock(&sci->sc_state_lock);
2489  loop:
2490         for (;;) {
2491                 int mode;
2492 
2493                 if (sci->sc_state & NILFS_SEGCTOR_QUIT)
2494                         goto end_thread;
2495 
2496                 if (timeout || sci->sc_seq_request != sci->sc_seq_done)
2497                         mode = SC_LSEG_SR;
2498                 else if (!sci->sc_flush_request)
2499                         break;
2500                 else
2501                         mode = nilfs_segctor_flush_mode(sci);
2502 
2503                 spin_unlock(&sci->sc_state_lock);
2504                 nilfs_segctor_thread_construct(sci, mode);
2505                 spin_lock(&sci->sc_state_lock);
2506                 timeout = 0;
2507         }
2508 
2509 
2510         if (freezing(current)) {
2511                 spin_unlock(&sci->sc_state_lock);
2512                 try_to_freeze();
2513                 spin_lock(&sci->sc_state_lock);
2514         } else {
2515                 DEFINE_WAIT(wait);
2516                 int should_sleep = 1;
2517 
2518                 prepare_to_wait(&sci->sc_wait_daemon, &wait,
2519                                 TASK_INTERRUPTIBLE);
2520 
2521                 if (sci->sc_seq_request != sci->sc_seq_done)
2522                         should_sleep = 0;
2523                 else if (sci->sc_flush_request)
2524                         should_sleep = 0;
2525                 else if (sci->sc_state & NILFS_SEGCTOR_COMMIT)
2526                         should_sleep = time_before(jiffies,
2527                                         sci->sc_timer.expires);
2528 
2529                 if (should_sleep) {
2530                         spin_unlock(&sci->sc_state_lock);
2531                         schedule();
2532                         spin_lock(&sci->sc_state_lock);
2533                 }
2534                 finish_wait(&sci->sc_wait_daemon, &wait);
2535                 timeout = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
2536                            time_after_eq(jiffies, sci->sc_timer.expires));
2537 
2538                 if (nilfs_sb_dirty(nilfs) && nilfs_sb_need_update(nilfs))
2539                         set_nilfs_discontinued(nilfs);
2540         }
2541         goto loop;
2542 
2543  end_thread:
2544         spin_unlock(&sci->sc_state_lock);
2545 
2546         /* end sync. */
2547         sci->sc_task = NULL;
2548         wake_up(&sci->sc_wait_task); /* for nilfs_segctor_kill_thread() */
2549         return 0;
2550 }
2551 
2552 static int nilfs_segctor_start_thread(struct nilfs_sc_info *sci)
2553 {
2554         struct task_struct *t;
2555 
2556         t = kthread_run(nilfs_segctor_thread, sci, "segctord");
2557         if (IS_ERR(t)) {
2558                 int err = PTR_ERR(t);
2559 
2560                 printk(KERN_ERR "NILFS: error %d creating segctord thread\n",
2561                        err);
2562                 return err;
2563         }
2564         wait_event(sci->sc_wait_task, sci->sc_task != NULL);
2565         return 0;
2566 }
2567 
2568 static void nilfs_segctor_kill_thread(struct nilfs_sc_info *sci)
2569         __acquires(&sci->sc_state_lock)
2570         __releases(&sci->sc_state_lock)
2571 {
2572         sci->sc_state |= NILFS_SEGCTOR_QUIT;
2573 
2574         while (sci->sc_task) {
2575                 wake_up(&sci->sc_wait_daemon);
2576                 spin_unlock(&sci->sc_state_lock);
2577                 wait_event(sci->sc_wait_task, sci->sc_task == NULL);
2578                 spin_lock(&sci->sc_state_lock);
2579         }
2580 }
2581 
2582 /*
2583  * Setup & clean-up functions
2584  */
2585 static struct nilfs_sc_info *nilfs_segctor_new(struct super_block *sb,
2586                                                struct nilfs_root *root)
2587 {
2588         struct the_nilfs *nilfs = sb->s_fs_info;
2589         struct nilfs_sc_info *sci;
2590 
2591         sci = kzalloc(sizeof(*sci), GFP_KERNEL);
2592         if (!sci)
2593                 return NULL;
2594 
2595         sci->sc_super = sb;
2596 
2597         nilfs_get_root(root);
2598         sci->sc_root = root;
2599 
2600         init_waitqueue_head(&sci->sc_wait_request);
2601         init_waitqueue_head(&sci->sc_wait_daemon);
2602         init_waitqueue_head(&sci->sc_wait_task);
2603         spin_lock_init(&sci->sc_state_lock);
2604         INIT_LIST_HEAD(&sci->sc_dirty_files);
2605         INIT_LIST_HEAD(&sci->sc_segbufs);
2606         INIT_LIST_HEAD(&sci->sc_write_logs);
2607         INIT_LIST_HEAD(&sci->sc_gc_inodes);
2608         INIT_LIST_HEAD(&sci->sc_iput_queue);
2609         INIT_WORK(&sci->sc_iput_work, nilfs_iput_work_func);
2610         init_timer(&sci->sc_timer);
2611 
2612         sci->sc_interval = HZ * NILFS_SC_DEFAULT_TIMEOUT;
2613         sci->sc_mjcp_freq = HZ * NILFS_SC_DEFAULT_SR_FREQ;
2614         sci->sc_watermark = NILFS_SC_DEFAULT_WATERMARK;
2615 
2616         if (nilfs->ns_interval)
2617                 sci->sc_interval = HZ * nilfs->ns_interval;
2618         if (nilfs->ns_watermark)
2619                 sci->sc_watermark = nilfs->ns_watermark;
2620         return sci;
2621 }
2622 
2623 static void nilfs_segctor_write_out(struct nilfs_sc_info *sci)
2624 {
2625         int ret, retrycount = NILFS_SC_CLEANUP_RETRY;
2626 
2627         /* The segctord thread was stopped and its timer was removed.
2628            But some tasks remain. */
2629         do {
2630                 struct nilfs_transaction_info ti;
2631 
2632                 nilfs_transaction_lock(sci->sc_super, &ti, 0);
2633                 ret = nilfs_segctor_construct(sci, SC_LSEG_SR);
2634                 nilfs_transaction_unlock(sci->sc_super);
2635 
2636                 flush_work(&sci->sc_iput_work);
2637 
2638         } while (ret && retrycount-- > 0);
2639 }
2640 
2641 /**
2642  * nilfs_segctor_destroy - destroy the segment constructor.
2643  * @sci: nilfs_sc_info
2644  *
2645  * nilfs_segctor_destroy() kills the segctord thread and frees
2646  * the nilfs_sc_info struct.
2647  * Caller must hold the segment semaphore.
2648  */
2649 static void nilfs_segctor_destroy(struct nilfs_sc_info *sci)
2650 {
2651         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2652         int flag;
2653 
2654         up_write(&nilfs->ns_segctor_sem);
2655 
2656         spin_lock(&sci->sc_state_lock);
2657         nilfs_segctor_kill_thread(sci);
2658         flag = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) || sci->sc_flush_request
2659                 || sci->sc_seq_request != sci->sc_seq_done);
2660         spin_unlock(&sci->sc_state_lock);
2661 
2662         if (flush_work(&sci->sc_iput_work))
2663                 flag = true;
2664 
2665         if (flag || !nilfs_segctor_confirm(sci))
2666                 nilfs_segctor_write_out(sci);
2667 
2668         if (!list_empty(&sci->sc_dirty_files)) {
2669                 nilfs_warning(sci->sc_super, __func__,
2670                               "dirty file(s) after the final construction\n");
2671                 nilfs_dispose_list(nilfs, &sci->sc_dirty_files, 1);
2672         }
2673 
2674         if (!list_empty(&sci->sc_iput_queue)) {
2675                 nilfs_warning(sci->sc_super, __func__,
2676                               "iput queue is not empty\n");
2677                 nilfs_dispose_list(nilfs, &sci->sc_iput_queue, 1);
2678         }
2679 
2680         WARN_ON(!list_empty(&sci->sc_segbufs));
2681         WARN_ON(!list_empty(&sci->sc_write_logs));
2682 
2683         nilfs_put_root(sci->sc_root);
2684 
2685         down_write(&nilfs->ns_segctor_sem);
2686 
2687         del_timer_sync(&sci->sc_timer);
2688         kfree(sci);
2689 }
2690 
2691 /**
2692  * nilfs_attach_log_writer - attach log writer
2693  * @sb: super block instance
2694  * @root: root object of the current filesystem tree
2695  *
2696  * This allocates a log writer object, initializes it, and starts the
2697  * log writer.
2698  *
2699  * Return Value: On success, 0 is returned. On error, one of the following
2700  * negative error code is returned.
2701  *
2702  * %-ENOMEM - Insufficient memory available.
2703  */
2704 int nilfs_attach_log_writer(struct super_block *sb, struct nilfs_root *root)
2705 {
2706         struct the_nilfs *nilfs = sb->s_fs_info;
2707         int err;
2708 
2709         if (nilfs->ns_writer) {
2710                 /*
2711                  * This happens if the filesystem was remounted
2712                  * read/write after nilfs_error degenerated it into a
2713                  * read-only mount.
2714                  */
2715                 nilfs_detach_log_writer(sb);
2716         }
2717 
2718         nilfs->ns_writer = nilfs_segctor_new(sb, root);
2719         if (!nilfs->ns_writer)
2720                 return -ENOMEM;
2721 
2722         err = nilfs_segctor_start_thread(nilfs->ns_writer);
2723         if (err) {
2724                 kfree(nilfs->ns_writer);
2725                 nilfs->ns_writer = NULL;
2726         }
2727         return err;
2728 }
2729 
2730 /**
2731  * nilfs_detach_log_writer - destroy log writer
2732  * @sb: super block instance
2733  *
2734  * This kills log writer daemon, frees the log writer object, and
2735  * destroys list of dirty files.
2736  */
2737 void nilfs_detach_log_writer(struct super_block *sb)
2738 {
2739         struct the_nilfs *nilfs = sb->s_fs_info;
2740         LIST_HEAD(garbage_list);
2741 
2742         down_write(&nilfs->ns_segctor_sem);
2743         if (nilfs->ns_writer) {
2744                 nilfs_segctor_destroy(nilfs->ns_writer);
2745                 nilfs->ns_writer = NULL;
2746         }
2747 
2748         /* Force to free the list of dirty files */
2749         spin_lock(&nilfs->ns_inode_lock);
2750         if (!list_empty(&nilfs->ns_dirty_files)) {
2751                 list_splice_init(&nilfs->ns_dirty_files, &garbage_list);
2752                 nilfs_warning(sb, __func__,
2753                               "Hit dirty file after stopped log writer\n");
2754         }
2755         spin_unlock(&nilfs->ns_inode_lock);
2756         up_write(&nilfs->ns_segctor_sem);
2757 
2758         nilfs_dispose_list(nilfs, &garbage_list, 1);
2759 }
2760 

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