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

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