xref: /openbmc/linux/fs/nilfs2/segment.c (revision 9d56dd3b083a3bec56e9da35ce07baca81030b03)
1 /*
2  * segment.c - NILFS segment constructor.
3  *
4  * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
19  *
20  * Written by Ryusuke Konishi <ryusuke@osrg.net>
21  *
22  */
23 
24 #include <linux/pagemap.h>
25 #include <linux/buffer_head.h>
26 #include <linux/writeback.h>
27 #include <linux/bio.h>
28 #include <linux/completion.h>
29 #include <linux/blkdev.h>
30 #include <linux/backing-dev.h>
31 #include <linux/freezer.h>
32 #include <linux/kthread.h>
33 #include <linux/crc32.h>
34 #include <linux/pagevec.h>
35 #include "nilfs.h"
36 #include "btnode.h"
37 #include "page.h"
38 #include "segment.h"
39 #include "sufile.h"
40 #include "cpfile.h"
41 #include "ifile.h"
42 #include "segbuf.h"
43 
44 
45 /*
46  * Segment constructor
47  */
48 #define SC_N_INODEVEC	16   /* Size of locally allocated inode vector */
49 
50 #define SC_MAX_SEGDELTA 64   /* Upper limit of the number of segments
51 				appended in collection retry loop */
52 
53 /* Construction mode */
54 enum {
55 	SC_LSEG_SR = 1,	/* Make a logical segment having a super root */
56 	SC_LSEG_DSYNC,	/* Flush data blocks of a given file and make
57 			   a logical segment without a super root */
58 	SC_FLUSH_FILE,	/* Flush data files, leads to segment writes without
59 			   creating a checkpoint */
60 	SC_FLUSH_DAT,	/* Flush DAT file. This also creates segments without
61 			   a checkpoint */
62 };
63 
64 /* Stage numbers of dirty block collection */
65 enum {
66 	NILFS_ST_INIT = 0,
67 	NILFS_ST_GC,		/* Collecting dirty blocks for GC */
68 	NILFS_ST_FILE,
69 	NILFS_ST_IFILE,
70 	NILFS_ST_CPFILE,
71 	NILFS_ST_SUFILE,
72 	NILFS_ST_DAT,
73 	NILFS_ST_SR,		/* Super root */
74 	NILFS_ST_DSYNC,		/* Data sync blocks */
75 	NILFS_ST_DONE,
76 };
77 
78 /* State flags of collection */
79 #define NILFS_CF_NODE		0x0001	/* Collecting node blocks */
80 #define NILFS_CF_IFILE_STARTED	0x0002	/* IFILE stage has started */
81 #define NILFS_CF_SUFREED	0x0004	/* segment usages has been freed */
82 #define NILFS_CF_HISTORY_MASK	(NILFS_CF_IFILE_STARTED | NILFS_CF_SUFREED)
83 
84 /* Operations depending on the construction mode and file type */
85 struct nilfs_sc_operations {
86 	int (*collect_data)(struct nilfs_sc_info *, struct buffer_head *,
87 			    struct inode *);
88 	int (*collect_node)(struct nilfs_sc_info *, struct buffer_head *,
89 			    struct inode *);
90 	int (*collect_bmap)(struct nilfs_sc_info *, struct buffer_head *,
91 			    struct inode *);
92 	void (*write_data_binfo)(struct nilfs_sc_info *,
93 				 struct nilfs_segsum_pointer *,
94 				 union nilfs_binfo *);
95 	void (*write_node_binfo)(struct nilfs_sc_info *,
96 				 struct nilfs_segsum_pointer *,
97 				 union nilfs_binfo *);
98 };
99 
100 /*
101  * Other definitions
102  */
103 static void nilfs_segctor_start_timer(struct nilfs_sc_info *);
104 static void nilfs_segctor_do_flush(struct nilfs_sc_info *, int);
105 static void nilfs_segctor_do_immediate_flush(struct nilfs_sc_info *);
106 static void nilfs_dispose_list(struct nilfs_sb_info *, struct list_head *,
107 			       int);
108 
109 #define nilfs_cnt32_gt(a, b)   \
110 	(typecheck(__u32, a) && typecheck(__u32, b) && \
111 	 ((__s32)(b) - (__s32)(a) < 0))
112 #define nilfs_cnt32_ge(a, b)   \
113 	(typecheck(__u32, a) && typecheck(__u32, b) && \
114 	 ((__s32)(a) - (__s32)(b) >= 0))
115 #define nilfs_cnt32_lt(a, b)  nilfs_cnt32_gt(b, a)
116 #define nilfs_cnt32_le(a, b)  nilfs_cnt32_ge(b, a)
117 
118 /*
119  * Transaction
120  */
121 static struct kmem_cache *nilfs_transaction_cachep;
122 
123 /**
124  * nilfs_init_transaction_cache - create a cache for nilfs_transaction_info
125  *
126  * nilfs_init_transaction_cache() creates a slab cache for the struct
127  * nilfs_transaction_info.
128  *
129  * Return Value: On success, it returns 0. On error, one of the following
130  * negative error code is returned.
131  *
132  * %-ENOMEM - Insufficient memory available.
133  */
134 int nilfs_init_transaction_cache(void)
135 {
136 	nilfs_transaction_cachep =
137 		kmem_cache_create("nilfs2_transaction_cache",
138 				  sizeof(struct nilfs_transaction_info),
139 				  0, SLAB_RECLAIM_ACCOUNT, NULL);
140 	return (nilfs_transaction_cachep == NULL) ? -ENOMEM : 0;
141 }
142 
143 /**
144  * nilfs_detroy_transaction_cache - destroy the cache for transaction info
145  *
146  * nilfs_destroy_transaction_cache() frees the slab cache for the struct
147  * nilfs_transaction_info.
148  */
149 void nilfs_destroy_transaction_cache(void)
150 {
151 	kmem_cache_destroy(nilfs_transaction_cachep);
152 }
153 
154 static int nilfs_prepare_segment_lock(struct nilfs_transaction_info *ti)
155 {
156 	struct nilfs_transaction_info *cur_ti = current->journal_info;
157 	void *save = NULL;
158 
159 	if (cur_ti) {
160 		if (cur_ti->ti_magic == NILFS_TI_MAGIC)
161 			return ++cur_ti->ti_count;
162 		else {
163 			/*
164 			 * If journal_info field is occupied by other FS,
165 			 * it is saved and will be restored on
166 			 * nilfs_transaction_commit().
167 			 */
168 			printk(KERN_WARNING
169 			       "NILFS warning: journal info from a different "
170 			       "FS\n");
171 			save = current->journal_info;
172 		}
173 	}
174 	if (!ti) {
175 		ti = kmem_cache_alloc(nilfs_transaction_cachep, GFP_NOFS);
176 		if (!ti)
177 			return -ENOMEM;
178 		ti->ti_flags = NILFS_TI_DYNAMIC_ALLOC;
179 	} else {
180 		ti->ti_flags = 0;
181 	}
182 	ti->ti_count = 0;
183 	ti->ti_save = save;
184 	ti->ti_magic = NILFS_TI_MAGIC;
185 	current->journal_info = ti;
186 	return 0;
187 }
188 
189 /**
190  * nilfs_transaction_begin - start indivisible file operations.
191  * @sb: super block
192  * @ti: nilfs_transaction_info
193  * @vacancy_check: flags for vacancy rate checks
194  *
195  * nilfs_transaction_begin() acquires a reader/writer semaphore, called
196  * the segment semaphore, to make a segment construction and write tasks
197  * exclusive.  The function is used with nilfs_transaction_commit() in pairs.
198  * The region enclosed by these two functions can be nested.  To avoid a
199  * deadlock, the semaphore is only acquired or released in the outermost call.
200  *
201  * This function allocates a nilfs_transaction_info struct to keep context
202  * information on it.  It is initialized and hooked onto the current task in
203  * the outermost call.  If a pre-allocated struct is given to @ti, it is used
204  * instead; othewise a new struct is assigned from a slab.
205  *
206  * When @vacancy_check flag is set, this function will check the amount of
207  * free space, and will wait for the GC to reclaim disk space if low capacity.
208  *
209  * Return Value: On success, 0 is returned. On error, one of the following
210  * negative error code is returned.
211  *
212  * %-ENOMEM - Insufficient memory available.
213  *
214  * %-ENOSPC - No space left on device
215  */
216 int nilfs_transaction_begin(struct super_block *sb,
217 			    struct nilfs_transaction_info *ti,
218 			    int vacancy_check)
219 {
220 	struct nilfs_sb_info *sbi;
221 	struct the_nilfs *nilfs;
222 	int ret = nilfs_prepare_segment_lock(ti);
223 
224 	if (unlikely(ret < 0))
225 		return ret;
226 	if (ret > 0)
227 		return 0;
228 
229 	sbi = NILFS_SB(sb);
230 	nilfs = sbi->s_nilfs;
231 	down_read(&nilfs->ns_segctor_sem);
232 	if (vacancy_check && nilfs_near_disk_full(nilfs)) {
233 		up_read(&nilfs->ns_segctor_sem);
234 		ret = -ENOSPC;
235 		goto failed;
236 	}
237 	return 0;
238 
239  failed:
240 	ti = current->journal_info;
241 	current->journal_info = ti->ti_save;
242 	if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
243 		kmem_cache_free(nilfs_transaction_cachep, ti);
244 	return ret;
245 }
246 
247 /**
248  * nilfs_transaction_commit - commit indivisible file operations.
249  * @sb: super block
250  *
251  * nilfs_transaction_commit() releases the read semaphore which is
252  * acquired by nilfs_transaction_begin(). This is only performed
253  * in outermost call of this function.  If a commit flag is set,
254  * nilfs_transaction_commit() sets a timer to start the segment
255  * constructor.  If a sync flag is set, it starts construction
256  * directly.
257  */
258 int nilfs_transaction_commit(struct super_block *sb)
259 {
260 	struct nilfs_transaction_info *ti = current->journal_info;
261 	struct nilfs_sb_info *sbi;
262 	struct nilfs_sc_info *sci;
263 	int err = 0;
264 
265 	BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
266 	ti->ti_flags |= NILFS_TI_COMMIT;
267 	if (ti->ti_count > 0) {
268 		ti->ti_count--;
269 		return 0;
270 	}
271 	sbi = NILFS_SB(sb);
272 	sci = NILFS_SC(sbi);
273 	if (sci != NULL) {
274 		if (ti->ti_flags & NILFS_TI_COMMIT)
275 			nilfs_segctor_start_timer(sci);
276 		if (atomic_read(&sbi->s_nilfs->ns_ndirtyblks) >
277 		    sci->sc_watermark)
278 			nilfs_segctor_do_flush(sci, 0);
279 	}
280 	up_read(&sbi->s_nilfs->ns_segctor_sem);
281 	current->journal_info = ti->ti_save;
282 
283 	if (ti->ti_flags & NILFS_TI_SYNC)
284 		err = nilfs_construct_segment(sb);
285 	if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
286 		kmem_cache_free(nilfs_transaction_cachep, ti);
287 	return err;
288 }
289 
290 void nilfs_transaction_abort(struct super_block *sb)
291 {
292 	struct nilfs_transaction_info *ti = current->journal_info;
293 
294 	BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
295 	if (ti->ti_count > 0) {
296 		ti->ti_count--;
297 		return;
298 	}
299 	up_read(&NILFS_SB(sb)->s_nilfs->ns_segctor_sem);
300 
301 	current->journal_info = ti->ti_save;
302 	if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
303 		kmem_cache_free(nilfs_transaction_cachep, ti);
304 }
305 
306 void nilfs_relax_pressure_in_lock(struct super_block *sb)
307 {
308 	struct nilfs_sb_info *sbi = NILFS_SB(sb);
309 	struct nilfs_sc_info *sci = NILFS_SC(sbi);
310 	struct the_nilfs *nilfs = sbi->s_nilfs;
311 
312 	if (!sci || !sci->sc_flush_request)
313 		return;
314 
315 	set_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags);
316 	up_read(&nilfs->ns_segctor_sem);
317 
318 	down_write(&nilfs->ns_segctor_sem);
319 	if (sci->sc_flush_request &&
320 	    test_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags)) {
321 		struct nilfs_transaction_info *ti = current->journal_info;
322 
323 		ti->ti_flags |= NILFS_TI_WRITER;
324 		nilfs_segctor_do_immediate_flush(sci);
325 		ti->ti_flags &= ~NILFS_TI_WRITER;
326 	}
327 	downgrade_write(&nilfs->ns_segctor_sem);
328 }
329 
330 static void nilfs_transaction_lock(struct nilfs_sb_info *sbi,
331 				   struct nilfs_transaction_info *ti,
332 				   int gcflag)
333 {
334 	struct nilfs_transaction_info *cur_ti = current->journal_info;
335 
336 	WARN_ON(cur_ti);
337 	ti->ti_flags = NILFS_TI_WRITER;
338 	ti->ti_count = 0;
339 	ti->ti_save = cur_ti;
340 	ti->ti_magic = NILFS_TI_MAGIC;
341 	INIT_LIST_HEAD(&ti->ti_garbage);
342 	current->journal_info = ti;
343 
344 	for (;;) {
345 		down_write(&sbi->s_nilfs->ns_segctor_sem);
346 		if (!test_bit(NILFS_SC_PRIOR_FLUSH, &NILFS_SC(sbi)->sc_flags))
347 			break;
348 
349 		nilfs_segctor_do_immediate_flush(NILFS_SC(sbi));
350 
351 		up_write(&sbi->s_nilfs->ns_segctor_sem);
352 		yield();
353 	}
354 	if (gcflag)
355 		ti->ti_flags |= NILFS_TI_GC;
356 }
357 
358 static void nilfs_transaction_unlock(struct nilfs_sb_info *sbi)
359 {
360 	struct nilfs_transaction_info *ti = current->journal_info;
361 
362 	BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
363 	BUG_ON(ti->ti_count > 0);
364 
365 	up_write(&sbi->s_nilfs->ns_segctor_sem);
366 	current->journal_info = ti->ti_save;
367 	if (!list_empty(&ti->ti_garbage))
368 		nilfs_dispose_list(sbi, &ti->ti_garbage, 0);
369 }
370 
371 static void *nilfs_segctor_map_segsum_entry(struct nilfs_sc_info *sci,
372 					    struct nilfs_segsum_pointer *ssp,
373 					    unsigned bytes)
374 {
375 	struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
376 	unsigned blocksize = sci->sc_super->s_blocksize;
377 	void *p;
378 
379 	if (unlikely(ssp->offset + bytes > blocksize)) {
380 		ssp->offset = 0;
381 		BUG_ON(NILFS_SEGBUF_BH_IS_LAST(ssp->bh,
382 					       &segbuf->sb_segsum_buffers));
383 		ssp->bh = NILFS_SEGBUF_NEXT_BH(ssp->bh);
384 	}
385 	p = ssp->bh->b_data + ssp->offset;
386 	ssp->offset += bytes;
387 	return p;
388 }
389 
390 /**
391  * nilfs_segctor_reset_segment_buffer - reset the current segment buffer
392  * @sci: nilfs_sc_info
393  */
394 static int nilfs_segctor_reset_segment_buffer(struct nilfs_sc_info *sci)
395 {
396 	struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
397 	struct buffer_head *sumbh;
398 	unsigned sumbytes;
399 	unsigned flags = 0;
400 	int err;
401 
402 	if (nilfs_doing_gc())
403 		flags = NILFS_SS_GC;
404 	err = nilfs_segbuf_reset(segbuf, flags, sci->sc_seg_ctime);
405 	if (unlikely(err))
406 		return err;
407 
408 	sumbh = NILFS_SEGBUF_FIRST_BH(&segbuf->sb_segsum_buffers);
409 	sumbytes = segbuf->sb_sum.sumbytes;
410 	sci->sc_finfo_ptr.bh = sumbh;  sci->sc_finfo_ptr.offset = sumbytes;
411 	sci->sc_binfo_ptr.bh = sumbh;  sci->sc_binfo_ptr.offset = sumbytes;
412 	sci->sc_blk_cnt = sci->sc_datablk_cnt = 0;
413 	return 0;
414 }
415 
416 static int nilfs_segctor_feed_segment(struct nilfs_sc_info *sci)
417 {
418 	sci->sc_nblk_this_inc += sci->sc_curseg->sb_sum.nblocks;
419 	if (NILFS_SEGBUF_IS_LAST(sci->sc_curseg, &sci->sc_segbufs))
420 		return -E2BIG; /* The current segment is filled up
421 				  (internal code) */
422 	sci->sc_curseg = NILFS_NEXT_SEGBUF(sci->sc_curseg);
423 	return nilfs_segctor_reset_segment_buffer(sci);
424 }
425 
426 static int nilfs_segctor_add_super_root(struct nilfs_sc_info *sci)
427 {
428 	struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
429 	int err;
430 
431 	if (segbuf->sb_sum.nblocks >= segbuf->sb_rest_blocks) {
432 		err = nilfs_segctor_feed_segment(sci);
433 		if (err)
434 			return err;
435 		segbuf = sci->sc_curseg;
436 	}
437 	err = nilfs_segbuf_extend_payload(segbuf, &sci->sc_super_root);
438 	if (likely(!err))
439 		segbuf->sb_sum.flags |= NILFS_SS_SR;
440 	return err;
441 }
442 
443 /*
444  * Functions for making segment summary and payloads
445  */
446 static int nilfs_segctor_segsum_block_required(
447 	struct nilfs_sc_info *sci, const struct nilfs_segsum_pointer *ssp,
448 	unsigned binfo_size)
449 {
450 	unsigned blocksize = sci->sc_super->s_blocksize;
451 	/* Size of finfo and binfo is enough small against blocksize */
452 
453 	return ssp->offset + binfo_size +
454 		(!sci->sc_blk_cnt ? sizeof(struct nilfs_finfo) : 0) >
455 		blocksize;
456 }
457 
458 static void nilfs_segctor_begin_finfo(struct nilfs_sc_info *sci,
459 				      struct inode *inode)
460 {
461 	sci->sc_curseg->sb_sum.nfinfo++;
462 	sci->sc_binfo_ptr = sci->sc_finfo_ptr;
463 	nilfs_segctor_map_segsum_entry(
464 		sci, &sci->sc_binfo_ptr, sizeof(struct nilfs_finfo));
465 
466 	if (inode->i_sb && !test_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags))
467 		set_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
468 	/* skip finfo */
469 }
470 
471 static void nilfs_segctor_end_finfo(struct nilfs_sc_info *sci,
472 				    struct inode *inode)
473 {
474 	struct nilfs_finfo *finfo;
475 	struct nilfs_inode_info *ii;
476 	struct nilfs_segment_buffer *segbuf;
477 
478 	if (sci->sc_blk_cnt == 0)
479 		return;
480 
481 	ii = NILFS_I(inode);
482 	finfo = nilfs_segctor_map_segsum_entry(sci, &sci->sc_finfo_ptr,
483 						 sizeof(*finfo));
484 	finfo->fi_ino = cpu_to_le64(inode->i_ino);
485 	finfo->fi_nblocks = cpu_to_le32(sci->sc_blk_cnt);
486 	finfo->fi_ndatablk = cpu_to_le32(sci->sc_datablk_cnt);
487 	finfo->fi_cno = cpu_to_le64(ii->i_cno);
488 
489 	segbuf = sci->sc_curseg;
490 	segbuf->sb_sum.sumbytes = sci->sc_binfo_ptr.offset +
491 		sci->sc_super->s_blocksize * (segbuf->sb_sum.nsumblk - 1);
492 	sci->sc_finfo_ptr = sci->sc_binfo_ptr;
493 	sci->sc_blk_cnt = sci->sc_datablk_cnt = 0;
494 }
495 
496 static int nilfs_segctor_add_file_block(struct nilfs_sc_info *sci,
497 					struct buffer_head *bh,
498 					struct inode *inode,
499 					unsigned binfo_size)
500 {
501 	struct nilfs_segment_buffer *segbuf;
502 	int required, err = 0;
503 
504  retry:
505 	segbuf = sci->sc_curseg;
506 	required = nilfs_segctor_segsum_block_required(
507 		sci, &sci->sc_binfo_ptr, binfo_size);
508 	if (segbuf->sb_sum.nblocks + required + 1 > segbuf->sb_rest_blocks) {
509 		nilfs_segctor_end_finfo(sci, inode);
510 		err = nilfs_segctor_feed_segment(sci);
511 		if (err)
512 			return err;
513 		goto retry;
514 	}
515 	if (unlikely(required)) {
516 		err = nilfs_segbuf_extend_segsum(segbuf);
517 		if (unlikely(err))
518 			goto failed;
519 	}
520 	if (sci->sc_blk_cnt == 0)
521 		nilfs_segctor_begin_finfo(sci, inode);
522 
523 	nilfs_segctor_map_segsum_entry(sci, &sci->sc_binfo_ptr, binfo_size);
524 	/* Substitution to vblocknr is delayed until update_blocknr() */
525 	nilfs_segbuf_add_file_buffer(segbuf, bh);
526 	sci->sc_blk_cnt++;
527  failed:
528 	return err;
529 }
530 
531 static int nilfs_handle_bmap_error(int err, const char *fname,
532 				   struct inode *inode, struct super_block *sb)
533 {
534 	if (err == -EINVAL) {
535 		nilfs_error(sb, fname, "broken bmap (inode=%lu)\n",
536 			    inode->i_ino);
537 		err = -EIO;
538 	}
539 	return err;
540 }
541 
542 /*
543  * Callback functions that enumerate, mark, and collect dirty blocks
544  */
545 static int nilfs_collect_file_data(struct nilfs_sc_info *sci,
546 				   struct buffer_head *bh, struct inode *inode)
547 {
548 	int err;
549 
550 	err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
551 	if (unlikely(err < 0))
552 		return nilfs_handle_bmap_error(err, __func__, inode,
553 					       sci->sc_super);
554 
555 	err = nilfs_segctor_add_file_block(sci, bh, inode,
556 					   sizeof(struct nilfs_binfo_v));
557 	if (!err)
558 		sci->sc_datablk_cnt++;
559 	return err;
560 }
561 
562 static int nilfs_collect_file_node(struct nilfs_sc_info *sci,
563 				   struct buffer_head *bh,
564 				   struct inode *inode)
565 {
566 	int err;
567 
568 	err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
569 	if (unlikely(err < 0))
570 		return nilfs_handle_bmap_error(err, __func__, inode,
571 					       sci->sc_super);
572 	return 0;
573 }
574 
575 static int nilfs_collect_file_bmap(struct nilfs_sc_info *sci,
576 				   struct buffer_head *bh,
577 				   struct inode *inode)
578 {
579 	WARN_ON(!buffer_dirty(bh));
580 	return nilfs_segctor_add_file_block(sci, bh, inode, sizeof(__le64));
581 }
582 
583 static void nilfs_write_file_data_binfo(struct nilfs_sc_info *sci,
584 					struct nilfs_segsum_pointer *ssp,
585 					union nilfs_binfo *binfo)
586 {
587 	struct nilfs_binfo_v *binfo_v = nilfs_segctor_map_segsum_entry(
588 		sci, ssp, sizeof(*binfo_v));
589 	*binfo_v = binfo->bi_v;
590 }
591 
592 static void nilfs_write_file_node_binfo(struct nilfs_sc_info *sci,
593 					struct nilfs_segsum_pointer *ssp,
594 					union nilfs_binfo *binfo)
595 {
596 	__le64 *vblocknr = nilfs_segctor_map_segsum_entry(
597 		sci, ssp, sizeof(*vblocknr));
598 	*vblocknr = binfo->bi_v.bi_vblocknr;
599 }
600 
601 struct nilfs_sc_operations nilfs_sc_file_ops = {
602 	.collect_data = nilfs_collect_file_data,
603 	.collect_node = nilfs_collect_file_node,
604 	.collect_bmap = nilfs_collect_file_bmap,
605 	.write_data_binfo = nilfs_write_file_data_binfo,
606 	.write_node_binfo = nilfs_write_file_node_binfo,
607 };
608 
609 static int nilfs_collect_dat_data(struct nilfs_sc_info *sci,
610 				  struct buffer_head *bh, struct inode *inode)
611 {
612 	int err;
613 
614 	err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
615 	if (unlikely(err < 0))
616 		return nilfs_handle_bmap_error(err, __func__, inode,
617 					       sci->sc_super);
618 
619 	err = nilfs_segctor_add_file_block(sci, bh, inode, sizeof(__le64));
620 	if (!err)
621 		sci->sc_datablk_cnt++;
622 	return err;
623 }
624 
625 static int nilfs_collect_dat_bmap(struct nilfs_sc_info *sci,
626 				  struct buffer_head *bh, struct inode *inode)
627 {
628 	WARN_ON(!buffer_dirty(bh));
629 	return nilfs_segctor_add_file_block(sci, bh, inode,
630 					    sizeof(struct nilfs_binfo_dat));
631 }
632 
633 static void nilfs_write_dat_data_binfo(struct nilfs_sc_info *sci,
634 				       struct nilfs_segsum_pointer *ssp,
635 				       union nilfs_binfo *binfo)
636 {
637 	__le64 *blkoff = nilfs_segctor_map_segsum_entry(sci, ssp,
638 							  sizeof(*blkoff));
639 	*blkoff = binfo->bi_dat.bi_blkoff;
640 }
641 
642 static void nilfs_write_dat_node_binfo(struct nilfs_sc_info *sci,
643 				       struct nilfs_segsum_pointer *ssp,
644 				       union nilfs_binfo *binfo)
645 {
646 	struct nilfs_binfo_dat *binfo_dat =
647 		nilfs_segctor_map_segsum_entry(sci, ssp, sizeof(*binfo_dat));
648 	*binfo_dat = binfo->bi_dat;
649 }
650 
651 struct nilfs_sc_operations nilfs_sc_dat_ops = {
652 	.collect_data = nilfs_collect_dat_data,
653 	.collect_node = nilfs_collect_file_node,
654 	.collect_bmap = nilfs_collect_dat_bmap,
655 	.write_data_binfo = nilfs_write_dat_data_binfo,
656 	.write_node_binfo = nilfs_write_dat_node_binfo,
657 };
658 
659 struct nilfs_sc_operations nilfs_sc_dsync_ops = {
660 	.collect_data = nilfs_collect_file_data,
661 	.collect_node = NULL,
662 	.collect_bmap = NULL,
663 	.write_data_binfo = nilfs_write_file_data_binfo,
664 	.write_node_binfo = NULL,
665 };
666 
667 static size_t nilfs_lookup_dirty_data_buffers(struct inode *inode,
668 					      struct list_head *listp,
669 					      size_t nlimit,
670 					      loff_t start, loff_t end)
671 {
672 	struct address_space *mapping = inode->i_mapping;
673 	struct pagevec pvec;
674 	pgoff_t index = 0, last = ULONG_MAX;
675 	size_t ndirties = 0;
676 	int i;
677 
678 	if (unlikely(start != 0 || end != LLONG_MAX)) {
679 		/*
680 		 * A valid range is given for sync-ing data pages. The
681 		 * range is rounded to per-page; extra dirty buffers
682 		 * may be included if blocksize < pagesize.
683 		 */
684 		index = start >> PAGE_SHIFT;
685 		last = end >> PAGE_SHIFT;
686 	}
687 	pagevec_init(&pvec, 0);
688  repeat:
689 	if (unlikely(index > last) ||
690 	    !pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
691 				min_t(pgoff_t, last - index,
692 				      PAGEVEC_SIZE - 1) + 1))
693 		return ndirties;
694 
695 	for (i = 0; i < pagevec_count(&pvec); i++) {
696 		struct buffer_head *bh, *head;
697 		struct page *page = pvec.pages[i];
698 
699 		if (unlikely(page->index > last))
700 			break;
701 
702 		if (mapping->host) {
703 			lock_page(page);
704 			if (!page_has_buffers(page))
705 				create_empty_buffers(page,
706 						     1 << inode->i_blkbits, 0);
707 			unlock_page(page);
708 		}
709 
710 		bh = head = page_buffers(page);
711 		do {
712 			if (!buffer_dirty(bh))
713 				continue;
714 			get_bh(bh);
715 			list_add_tail(&bh->b_assoc_buffers, listp);
716 			ndirties++;
717 			if (unlikely(ndirties >= nlimit)) {
718 				pagevec_release(&pvec);
719 				cond_resched();
720 				return ndirties;
721 			}
722 		} while (bh = bh->b_this_page, bh != head);
723 	}
724 	pagevec_release(&pvec);
725 	cond_resched();
726 	goto repeat;
727 }
728 
729 static void nilfs_lookup_dirty_node_buffers(struct inode *inode,
730 					    struct list_head *listp)
731 {
732 	struct nilfs_inode_info *ii = NILFS_I(inode);
733 	struct address_space *mapping = &ii->i_btnode_cache;
734 	struct pagevec pvec;
735 	struct buffer_head *bh, *head;
736 	unsigned int i;
737 	pgoff_t index = 0;
738 
739 	pagevec_init(&pvec, 0);
740 
741 	while (pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
742 				  PAGEVEC_SIZE)) {
743 		for (i = 0; i < pagevec_count(&pvec); i++) {
744 			bh = head = page_buffers(pvec.pages[i]);
745 			do {
746 				if (buffer_dirty(bh)) {
747 					get_bh(bh);
748 					list_add_tail(&bh->b_assoc_buffers,
749 						      listp);
750 				}
751 				bh = bh->b_this_page;
752 			} while (bh != head);
753 		}
754 		pagevec_release(&pvec);
755 		cond_resched();
756 	}
757 }
758 
759 static void nilfs_dispose_list(struct nilfs_sb_info *sbi,
760 			       struct list_head *head, int force)
761 {
762 	struct nilfs_inode_info *ii, *n;
763 	struct nilfs_inode_info *ivec[SC_N_INODEVEC], **pii;
764 	unsigned nv = 0;
765 
766 	while (!list_empty(head)) {
767 		spin_lock(&sbi->s_inode_lock);
768 		list_for_each_entry_safe(ii, n, head, i_dirty) {
769 			list_del_init(&ii->i_dirty);
770 			if (force) {
771 				if (unlikely(ii->i_bh)) {
772 					brelse(ii->i_bh);
773 					ii->i_bh = NULL;
774 				}
775 			} else if (test_bit(NILFS_I_DIRTY, &ii->i_state)) {
776 				set_bit(NILFS_I_QUEUED, &ii->i_state);
777 				list_add_tail(&ii->i_dirty,
778 					      &sbi->s_dirty_files);
779 				continue;
780 			}
781 			ivec[nv++] = ii;
782 			if (nv == SC_N_INODEVEC)
783 				break;
784 		}
785 		spin_unlock(&sbi->s_inode_lock);
786 
787 		for (pii = ivec; nv > 0; pii++, nv--)
788 			iput(&(*pii)->vfs_inode);
789 	}
790 }
791 
792 static int nilfs_test_metadata_dirty(struct nilfs_sb_info *sbi)
793 {
794 	struct the_nilfs *nilfs = sbi->s_nilfs;
795 	int ret = 0;
796 
797 	if (nilfs_mdt_fetch_dirty(sbi->s_ifile))
798 		ret++;
799 	if (nilfs_mdt_fetch_dirty(nilfs->ns_cpfile))
800 		ret++;
801 	if (nilfs_mdt_fetch_dirty(nilfs->ns_sufile))
802 		ret++;
803 	if (ret || nilfs_doing_gc())
804 		if (nilfs_mdt_fetch_dirty(nilfs_dat_inode(nilfs)))
805 			ret++;
806 	return ret;
807 }
808 
809 static int nilfs_segctor_clean(struct nilfs_sc_info *sci)
810 {
811 	return list_empty(&sci->sc_dirty_files) &&
812 		!test_bit(NILFS_SC_DIRTY, &sci->sc_flags) &&
813 		sci->sc_nfreesegs == 0 &&
814 		(!nilfs_doing_gc() || list_empty(&sci->sc_gc_inodes));
815 }
816 
817 static int nilfs_segctor_confirm(struct nilfs_sc_info *sci)
818 {
819 	struct nilfs_sb_info *sbi = sci->sc_sbi;
820 	int ret = 0;
821 
822 	if (nilfs_test_metadata_dirty(sbi))
823 		set_bit(NILFS_SC_DIRTY, &sci->sc_flags);
824 
825 	spin_lock(&sbi->s_inode_lock);
826 	if (list_empty(&sbi->s_dirty_files) && nilfs_segctor_clean(sci))
827 		ret++;
828 
829 	spin_unlock(&sbi->s_inode_lock);
830 	return ret;
831 }
832 
833 static void nilfs_segctor_clear_metadata_dirty(struct nilfs_sc_info *sci)
834 {
835 	struct nilfs_sb_info *sbi = sci->sc_sbi;
836 	struct the_nilfs *nilfs = sbi->s_nilfs;
837 
838 	nilfs_mdt_clear_dirty(sbi->s_ifile);
839 	nilfs_mdt_clear_dirty(nilfs->ns_cpfile);
840 	nilfs_mdt_clear_dirty(nilfs->ns_sufile);
841 	nilfs_mdt_clear_dirty(nilfs_dat_inode(nilfs));
842 }
843 
844 static int nilfs_segctor_create_checkpoint(struct nilfs_sc_info *sci)
845 {
846 	struct the_nilfs *nilfs = sci->sc_sbi->s_nilfs;
847 	struct buffer_head *bh_cp;
848 	struct nilfs_checkpoint *raw_cp;
849 	int err;
850 
851 	/* XXX: this interface will be changed */
852 	err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, 1,
853 					  &raw_cp, &bh_cp);
854 	if (likely(!err)) {
855 		/* The following code is duplicated with cpfile.  But, it is
856 		   needed to collect the checkpoint even if it was not newly
857 		   created */
858 		nilfs_mdt_mark_buffer_dirty(bh_cp);
859 		nilfs_mdt_mark_dirty(nilfs->ns_cpfile);
860 		nilfs_cpfile_put_checkpoint(
861 			nilfs->ns_cpfile, nilfs->ns_cno, bh_cp);
862 	} else
863 		WARN_ON(err == -EINVAL || err == -ENOENT);
864 
865 	return err;
866 }
867 
868 static int nilfs_segctor_fill_in_checkpoint(struct nilfs_sc_info *sci)
869 {
870 	struct nilfs_sb_info *sbi = sci->sc_sbi;
871 	struct the_nilfs *nilfs = sbi->s_nilfs;
872 	struct buffer_head *bh_cp;
873 	struct nilfs_checkpoint *raw_cp;
874 	int err;
875 
876 	err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, 0,
877 					  &raw_cp, &bh_cp);
878 	if (unlikely(err)) {
879 		WARN_ON(err == -EINVAL || err == -ENOENT);
880 		goto failed_ibh;
881 	}
882 	raw_cp->cp_snapshot_list.ssl_next = 0;
883 	raw_cp->cp_snapshot_list.ssl_prev = 0;
884 	raw_cp->cp_inodes_count =
885 		cpu_to_le64(atomic_read(&sbi->s_inodes_count));
886 	raw_cp->cp_blocks_count =
887 		cpu_to_le64(atomic_read(&sbi->s_blocks_count));
888 	raw_cp->cp_nblk_inc =
889 		cpu_to_le64(sci->sc_nblk_inc + sci->sc_nblk_this_inc);
890 	raw_cp->cp_create = cpu_to_le64(sci->sc_seg_ctime);
891 	raw_cp->cp_cno = cpu_to_le64(nilfs->ns_cno);
892 
893 	if (test_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags))
894 		nilfs_checkpoint_clear_minor(raw_cp);
895 	else
896 		nilfs_checkpoint_set_minor(raw_cp);
897 
898 	nilfs_write_inode_common(sbi->s_ifile, &raw_cp->cp_ifile_inode, 1);
899 	nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, bh_cp);
900 	return 0;
901 
902  failed_ibh:
903 	return err;
904 }
905 
906 static void nilfs_fill_in_file_bmap(struct inode *ifile,
907 				    struct nilfs_inode_info *ii)
908 
909 {
910 	struct buffer_head *ibh;
911 	struct nilfs_inode *raw_inode;
912 
913 	if (test_bit(NILFS_I_BMAP, &ii->i_state)) {
914 		ibh = ii->i_bh;
915 		BUG_ON(!ibh);
916 		raw_inode = nilfs_ifile_map_inode(ifile, ii->vfs_inode.i_ino,
917 						  ibh);
918 		nilfs_bmap_write(ii->i_bmap, raw_inode);
919 		nilfs_ifile_unmap_inode(ifile, ii->vfs_inode.i_ino, ibh);
920 	}
921 }
922 
923 static void nilfs_segctor_fill_in_file_bmap(struct nilfs_sc_info *sci,
924 					    struct inode *ifile)
925 {
926 	struct nilfs_inode_info *ii;
927 
928 	list_for_each_entry(ii, &sci->sc_dirty_files, i_dirty) {
929 		nilfs_fill_in_file_bmap(ifile, ii);
930 		set_bit(NILFS_I_COLLECTED, &ii->i_state);
931 	}
932 }
933 
934 /*
935  * CRC calculation routines
936  */
937 static void nilfs_fill_in_super_root_crc(struct buffer_head *bh_sr, u32 seed)
938 {
939 	struct nilfs_super_root *raw_sr =
940 		(struct nilfs_super_root *)bh_sr->b_data;
941 	u32 crc;
942 
943 	crc = crc32_le(seed,
944 		       (unsigned char *)raw_sr + sizeof(raw_sr->sr_sum),
945 		       NILFS_SR_BYTES - sizeof(raw_sr->sr_sum));
946 	raw_sr->sr_sum = cpu_to_le32(crc);
947 }
948 
949 static void nilfs_segctor_fill_in_checksums(struct nilfs_sc_info *sci,
950 					    u32 seed)
951 {
952 	struct nilfs_segment_buffer *segbuf;
953 
954 	if (sci->sc_super_root)
955 		nilfs_fill_in_super_root_crc(sci->sc_super_root, seed);
956 
957 	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
958 		nilfs_segbuf_fill_in_segsum_crc(segbuf, seed);
959 		nilfs_segbuf_fill_in_data_crc(segbuf, seed);
960 	}
961 }
962 
963 static void nilfs_segctor_fill_in_super_root(struct nilfs_sc_info *sci,
964 					     struct the_nilfs *nilfs)
965 {
966 	struct buffer_head *bh_sr = sci->sc_super_root;
967 	struct nilfs_super_root *raw_sr =
968 		(struct nilfs_super_root *)bh_sr->b_data;
969 	unsigned isz = nilfs->ns_inode_size;
970 
971 	raw_sr->sr_bytes = cpu_to_le16(NILFS_SR_BYTES);
972 	raw_sr->sr_nongc_ctime
973 		= cpu_to_le64(nilfs_doing_gc() ?
974 			      nilfs->ns_nongc_ctime : sci->sc_seg_ctime);
975 	raw_sr->sr_flags = 0;
976 
977 	nilfs_write_inode_common(nilfs_dat_inode(nilfs), (void *)raw_sr +
978 				 NILFS_SR_DAT_OFFSET(isz), 1);
979 	nilfs_write_inode_common(nilfs->ns_cpfile, (void *)raw_sr +
980 				 NILFS_SR_CPFILE_OFFSET(isz), 1);
981 	nilfs_write_inode_common(nilfs->ns_sufile, (void *)raw_sr +
982 				 NILFS_SR_SUFILE_OFFSET(isz), 1);
983 }
984 
985 static void nilfs_redirty_inodes(struct list_head *head)
986 {
987 	struct nilfs_inode_info *ii;
988 
989 	list_for_each_entry(ii, head, i_dirty) {
990 		if (test_bit(NILFS_I_COLLECTED, &ii->i_state))
991 			clear_bit(NILFS_I_COLLECTED, &ii->i_state);
992 	}
993 }
994 
995 static void nilfs_drop_collected_inodes(struct list_head *head)
996 {
997 	struct nilfs_inode_info *ii;
998 
999 	list_for_each_entry(ii, head, i_dirty) {
1000 		if (!test_and_clear_bit(NILFS_I_COLLECTED, &ii->i_state))
1001 			continue;
1002 
1003 		clear_bit(NILFS_I_INODE_DIRTY, &ii->i_state);
1004 		set_bit(NILFS_I_UPDATED, &ii->i_state);
1005 	}
1006 }
1007 
1008 static int nilfs_segctor_apply_buffers(struct nilfs_sc_info *sci,
1009 				       struct inode *inode,
1010 				       struct list_head *listp,
1011 				       int (*collect)(struct nilfs_sc_info *,
1012 						      struct buffer_head *,
1013 						      struct inode *))
1014 {
1015 	struct buffer_head *bh, *n;
1016 	int err = 0;
1017 
1018 	if (collect) {
1019 		list_for_each_entry_safe(bh, n, listp, b_assoc_buffers) {
1020 			list_del_init(&bh->b_assoc_buffers);
1021 			err = collect(sci, bh, inode);
1022 			brelse(bh);
1023 			if (unlikely(err))
1024 				goto dispose_buffers;
1025 		}
1026 		return 0;
1027 	}
1028 
1029  dispose_buffers:
1030 	while (!list_empty(listp)) {
1031 		bh = list_entry(listp->next, struct buffer_head,
1032 				b_assoc_buffers);
1033 		list_del_init(&bh->b_assoc_buffers);
1034 		brelse(bh);
1035 	}
1036 	return err;
1037 }
1038 
1039 static size_t nilfs_segctor_buffer_rest(struct nilfs_sc_info *sci)
1040 {
1041 	/* Remaining number of blocks within segment buffer */
1042 	return sci->sc_segbuf_nblocks -
1043 		(sci->sc_nblk_this_inc + sci->sc_curseg->sb_sum.nblocks);
1044 }
1045 
1046 static int nilfs_segctor_scan_file(struct nilfs_sc_info *sci,
1047 				   struct inode *inode,
1048 				   struct nilfs_sc_operations *sc_ops)
1049 {
1050 	LIST_HEAD(data_buffers);
1051 	LIST_HEAD(node_buffers);
1052 	int err;
1053 
1054 	if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
1055 		size_t n, rest = nilfs_segctor_buffer_rest(sci);
1056 
1057 		n = nilfs_lookup_dirty_data_buffers(
1058 			inode, &data_buffers, rest + 1, 0, LLONG_MAX);
1059 		if (n > rest) {
1060 			err = nilfs_segctor_apply_buffers(
1061 				sci, inode, &data_buffers,
1062 				sc_ops->collect_data);
1063 			BUG_ON(!err); /* always receive -E2BIG or true error */
1064 			goto break_or_fail;
1065 		}
1066 	}
1067 	nilfs_lookup_dirty_node_buffers(inode, &node_buffers);
1068 
1069 	if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
1070 		err = nilfs_segctor_apply_buffers(
1071 			sci, inode, &data_buffers, sc_ops->collect_data);
1072 		if (unlikely(err)) {
1073 			/* dispose node list */
1074 			nilfs_segctor_apply_buffers(
1075 				sci, inode, &node_buffers, NULL);
1076 			goto break_or_fail;
1077 		}
1078 		sci->sc_stage.flags |= NILFS_CF_NODE;
1079 	}
1080 	/* Collect node */
1081 	err = nilfs_segctor_apply_buffers(
1082 		sci, inode, &node_buffers, sc_ops->collect_node);
1083 	if (unlikely(err))
1084 		goto break_or_fail;
1085 
1086 	nilfs_bmap_lookup_dirty_buffers(NILFS_I(inode)->i_bmap, &node_buffers);
1087 	err = nilfs_segctor_apply_buffers(
1088 		sci, inode, &node_buffers, sc_ops->collect_bmap);
1089 	if (unlikely(err))
1090 		goto break_or_fail;
1091 
1092 	nilfs_segctor_end_finfo(sci, inode);
1093 	sci->sc_stage.flags &= ~NILFS_CF_NODE;
1094 
1095  break_or_fail:
1096 	return err;
1097 }
1098 
1099 static int nilfs_segctor_scan_file_dsync(struct nilfs_sc_info *sci,
1100 					 struct inode *inode)
1101 {
1102 	LIST_HEAD(data_buffers);
1103 	size_t n, rest = nilfs_segctor_buffer_rest(sci);
1104 	int err;
1105 
1106 	n = nilfs_lookup_dirty_data_buffers(inode, &data_buffers, rest + 1,
1107 					    sci->sc_dsync_start,
1108 					    sci->sc_dsync_end);
1109 
1110 	err = nilfs_segctor_apply_buffers(sci, inode, &data_buffers,
1111 					  nilfs_collect_file_data);
1112 	if (!err) {
1113 		nilfs_segctor_end_finfo(sci, inode);
1114 		BUG_ON(n > rest);
1115 		/* always receive -E2BIG or true error if n > rest */
1116 	}
1117 	return err;
1118 }
1119 
1120 static int nilfs_segctor_collect_blocks(struct nilfs_sc_info *sci, int mode)
1121 {
1122 	struct nilfs_sb_info *sbi = sci->sc_sbi;
1123 	struct the_nilfs *nilfs = sbi->s_nilfs;
1124 	struct list_head *head;
1125 	struct nilfs_inode_info *ii;
1126 	size_t ndone;
1127 	int err = 0;
1128 
1129 	switch (sci->sc_stage.scnt) {
1130 	case NILFS_ST_INIT:
1131 		/* Pre-processes */
1132 		sci->sc_stage.flags = 0;
1133 
1134 		if (!test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags)) {
1135 			sci->sc_nblk_inc = 0;
1136 			sci->sc_curseg->sb_sum.flags = NILFS_SS_LOGBGN;
1137 			if (mode == SC_LSEG_DSYNC) {
1138 				sci->sc_stage.scnt = NILFS_ST_DSYNC;
1139 				goto dsync_mode;
1140 			}
1141 		}
1142 
1143 		sci->sc_stage.dirty_file_ptr = NULL;
1144 		sci->sc_stage.gc_inode_ptr = NULL;
1145 		if (mode == SC_FLUSH_DAT) {
1146 			sci->sc_stage.scnt = NILFS_ST_DAT;
1147 			goto dat_stage;
1148 		}
1149 		sci->sc_stage.scnt++;  /* Fall through */
1150 	case NILFS_ST_GC:
1151 		if (nilfs_doing_gc()) {
1152 			head = &sci->sc_gc_inodes;
1153 			ii = list_prepare_entry(sci->sc_stage.gc_inode_ptr,
1154 						head, i_dirty);
1155 			list_for_each_entry_continue(ii, head, i_dirty) {
1156 				err = nilfs_segctor_scan_file(
1157 					sci, &ii->vfs_inode,
1158 					&nilfs_sc_file_ops);
1159 				if (unlikely(err)) {
1160 					sci->sc_stage.gc_inode_ptr = list_entry(
1161 						ii->i_dirty.prev,
1162 						struct nilfs_inode_info,
1163 						i_dirty);
1164 					goto break_or_fail;
1165 				}
1166 				set_bit(NILFS_I_COLLECTED, &ii->i_state);
1167 			}
1168 			sci->sc_stage.gc_inode_ptr = NULL;
1169 		}
1170 		sci->sc_stage.scnt++;  /* Fall through */
1171 	case NILFS_ST_FILE:
1172 		head = &sci->sc_dirty_files;
1173 		ii = list_prepare_entry(sci->sc_stage.dirty_file_ptr, head,
1174 					i_dirty);
1175 		list_for_each_entry_continue(ii, head, i_dirty) {
1176 			clear_bit(NILFS_I_DIRTY, &ii->i_state);
1177 
1178 			err = nilfs_segctor_scan_file(sci, &ii->vfs_inode,
1179 						      &nilfs_sc_file_ops);
1180 			if (unlikely(err)) {
1181 				sci->sc_stage.dirty_file_ptr =
1182 					list_entry(ii->i_dirty.prev,
1183 						   struct nilfs_inode_info,
1184 						   i_dirty);
1185 				goto break_or_fail;
1186 			}
1187 			/* sci->sc_stage.dirty_file_ptr = NILFS_I(inode); */
1188 			/* XXX: required ? */
1189 		}
1190 		sci->sc_stage.dirty_file_ptr = NULL;
1191 		if (mode == SC_FLUSH_FILE) {
1192 			sci->sc_stage.scnt = NILFS_ST_DONE;
1193 			return 0;
1194 		}
1195 		sci->sc_stage.scnt++;
1196 		sci->sc_stage.flags |= NILFS_CF_IFILE_STARTED;
1197 		/* Fall through */
1198 	case NILFS_ST_IFILE:
1199 		err = nilfs_segctor_scan_file(sci, sbi->s_ifile,
1200 					      &nilfs_sc_file_ops);
1201 		if (unlikely(err))
1202 			break;
1203 		sci->sc_stage.scnt++;
1204 		/* Creating a checkpoint */
1205 		err = nilfs_segctor_create_checkpoint(sci);
1206 		if (unlikely(err))
1207 			break;
1208 		/* Fall through */
1209 	case NILFS_ST_CPFILE:
1210 		err = nilfs_segctor_scan_file(sci, nilfs->ns_cpfile,
1211 					      &nilfs_sc_file_ops);
1212 		if (unlikely(err))
1213 			break;
1214 		sci->sc_stage.scnt++;  /* Fall through */
1215 	case NILFS_ST_SUFILE:
1216 		err = nilfs_sufile_freev(nilfs->ns_sufile, sci->sc_freesegs,
1217 					 sci->sc_nfreesegs, &ndone);
1218 		if (unlikely(err)) {
1219 			nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1220 						  sci->sc_freesegs, ndone,
1221 						  NULL);
1222 			break;
1223 		}
1224 		sci->sc_stage.flags |= NILFS_CF_SUFREED;
1225 
1226 		err = nilfs_segctor_scan_file(sci, nilfs->ns_sufile,
1227 					      &nilfs_sc_file_ops);
1228 		if (unlikely(err))
1229 			break;
1230 		sci->sc_stage.scnt++;  /* Fall through */
1231 	case NILFS_ST_DAT:
1232  dat_stage:
1233 		err = nilfs_segctor_scan_file(sci, nilfs_dat_inode(nilfs),
1234 					      &nilfs_sc_dat_ops);
1235 		if (unlikely(err))
1236 			break;
1237 		if (mode == SC_FLUSH_DAT) {
1238 			sci->sc_stage.scnt = NILFS_ST_DONE;
1239 			return 0;
1240 		}
1241 		sci->sc_stage.scnt++;  /* Fall through */
1242 	case NILFS_ST_SR:
1243 		if (mode == SC_LSEG_SR) {
1244 			/* Appending a super root */
1245 			err = nilfs_segctor_add_super_root(sci);
1246 			if (unlikely(err))
1247 				break;
1248 		}
1249 		/* End of a logical segment */
1250 		sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
1251 		sci->sc_stage.scnt = NILFS_ST_DONE;
1252 		return 0;
1253 	case NILFS_ST_DSYNC:
1254  dsync_mode:
1255 		sci->sc_curseg->sb_sum.flags |= NILFS_SS_SYNDT;
1256 		ii = sci->sc_dsync_inode;
1257 		if (!test_bit(NILFS_I_BUSY, &ii->i_state))
1258 			break;
1259 
1260 		err = nilfs_segctor_scan_file_dsync(sci, &ii->vfs_inode);
1261 		if (unlikely(err))
1262 			break;
1263 		sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
1264 		sci->sc_stage.scnt = NILFS_ST_DONE;
1265 		return 0;
1266 	case NILFS_ST_DONE:
1267 		return 0;
1268 	default:
1269 		BUG();
1270 	}
1271 
1272  break_or_fail:
1273 	return err;
1274 }
1275 
1276 /**
1277  * nilfs_segctor_begin_construction - setup segment buffer to make a new log
1278  * @sci: nilfs_sc_info
1279  * @nilfs: nilfs object
1280  */
1281 static int nilfs_segctor_begin_construction(struct nilfs_sc_info *sci,
1282 					    struct the_nilfs *nilfs)
1283 {
1284 	struct nilfs_segment_buffer *segbuf, *prev;
1285 	__u64 nextnum;
1286 	int err, alloc = 0;
1287 
1288 	segbuf = nilfs_segbuf_new(sci->sc_super);
1289 	if (unlikely(!segbuf))
1290 		return -ENOMEM;
1291 
1292 	if (list_empty(&sci->sc_write_logs)) {
1293 		nilfs_segbuf_map(segbuf, nilfs->ns_segnum,
1294 				 nilfs->ns_pseg_offset, nilfs);
1295 		if (segbuf->sb_rest_blocks < NILFS_PSEG_MIN_BLOCKS) {
1296 			nilfs_shift_to_next_segment(nilfs);
1297 			nilfs_segbuf_map(segbuf, nilfs->ns_segnum, 0, nilfs);
1298 		}
1299 
1300 		segbuf->sb_sum.seg_seq = nilfs->ns_seg_seq;
1301 		nextnum = nilfs->ns_nextnum;
1302 
1303 		if (nilfs->ns_segnum == nilfs->ns_nextnum)
1304 			/* Start from the head of a new full segment */
1305 			alloc++;
1306 	} else {
1307 		/* Continue logs */
1308 		prev = NILFS_LAST_SEGBUF(&sci->sc_write_logs);
1309 		nilfs_segbuf_map_cont(segbuf, prev);
1310 		segbuf->sb_sum.seg_seq = prev->sb_sum.seg_seq;
1311 		nextnum = prev->sb_nextnum;
1312 
1313 		if (segbuf->sb_rest_blocks < NILFS_PSEG_MIN_BLOCKS) {
1314 			nilfs_segbuf_map(segbuf, prev->sb_nextnum, 0, nilfs);
1315 			segbuf->sb_sum.seg_seq++;
1316 			alloc++;
1317 		}
1318 	}
1319 
1320 	err = nilfs_sufile_mark_dirty(nilfs->ns_sufile, segbuf->sb_segnum);
1321 	if (err)
1322 		goto failed;
1323 
1324 	if (alloc) {
1325 		err = nilfs_sufile_alloc(nilfs->ns_sufile, &nextnum);
1326 		if (err)
1327 			goto failed;
1328 	}
1329 	nilfs_segbuf_set_next_segnum(segbuf, nextnum, nilfs);
1330 
1331 	BUG_ON(!list_empty(&sci->sc_segbufs));
1332 	list_add_tail(&segbuf->sb_list, &sci->sc_segbufs);
1333 	sci->sc_segbuf_nblocks = segbuf->sb_rest_blocks;
1334 	return 0;
1335 
1336  failed:
1337 	nilfs_segbuf_free(segbuf);
1338 	return err;
1339 }
1340 
1341 static int nilfs_segctor_extend_segments(struct nilfs_sc_info *sci,
1342 					 struct the_nilfs *nilfs, int nadd)
1343 {
1344 	struct nilfs_segment_buffer *segbuf, *prev;
1345 	struct inode *sufile = nilfs->ns_sufile;
1346 	__u64 nextnextnum;
1347 	LIST_HEAD(list);
1348 	int err, ret, i;
1349 
1350 	prev = NILFS_LAST_SEGBUF(&sci->sc_segbufs);
1351 	/*
1352 	 * Since the segment specified with nextnum might be allocated during
1353 	 * the previous construction, the buffer including its segusage may
1354 	 * not be dirty.  The following call ensures that the buffer is dirty
1355 	 * and will pin the buffer on memory until the sufile is written.
1356 	 */
1357 	err = nilfs_sufile_mark_dirty(sufile, prev->sb_nextnum);
1358 	if (unlikely(err))
1359 		return err;
1360 
1361 	for (i = 0; i < nadd; i++) {
1362 		/* extend segment info */
1363 		err = -ENOMEM;
1364 		segbuf = nilfs_segbuf_new(sci->sc_super);
1365 		if (unlikely(!segbuf))
1366 			goto failed;
1367 
1368 		/* map this buffer to region of segment on-disk */
1369 		nilfs_segbuf_map(segbuf, prev->sb_nextnum, 0, nilfs);
1370 		sci->sc_segbuf_nblocks += segbuf->sb_rest_blocks;
1371 
1372 		/* allocate the next next full segment */
1373 		err = nilfs_sufile_alloc(sufile, &nextnextnum);
1374 		if (unlikely(err))
1375 			goto failed_segbuf;
1376 
1377 		segbuf->sb_sum.seg_seq = prev->sb_sum.seg_seq + 1;
1378 		nilfs_segbuf_set_next_segnum(segbuf, nextnextnum, nilfs);
1379 
1380 		list_add_tail(&segbuf->sb_list, &list);
1381 		prev = segbuf;
1382 	}
1383 	list_splice_tail(&list, &sci->sc_segbufs);
1384 	return 0;
1385 
1386  failed_segbuf:
1387 	nilfs_segbuf_free(segbuf);
1388  failed:
1389 	list_for_each_entry(segbuf, &list, sb_list) {
1390 		ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1391 		WARN_ON(ret); /* never fails */
1392 	}
1393 	nilfs_destroy_logs(&list);
1394 	return err;
1395 }
1396 
1397 static void nilfs_free_incomplete_logs(struct list_head *logs,
1398 				       struct the_nilfs *nilfs)
1399 {
1400 	struct nilfs_segment_buffer *segbuf, *prev;
1401 	struct inode *sufile = nilfs->ns_sufile;
1402 	int ret;
1403 
1404 	segbuf = NILFS_FIRST_SEGBUF(logs);
1405 	if (nilfs->ns_nextnum != segbuf->sb_nextnum) {
1406 		ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1407 		WARN_ON(ret); /* never fails */
1408 	}
1409 	if (atomic_read(&segbuf->sb_err)) {
1410 		/* Case 1: The first segment failed */
1411 		if (segbuf->sb_pseg_start != segbuf->sb_fseg_start)
1412 			/* Case 1a:  Partial segment appended into an existing
1413 			   segment */
1414 			nilfs_terminate_segment(nilfs, segbuf->sb_fseg_start,
1415 						segbuf->sb_fseg_end);
1416 		else /* Case 1b:  New full segment */
1417 			set_nilfs_discontinued(nilfs);
1418 	}
1419 
1420 	prev = segbuf;
1421 	list_for_each_entry_continue(segbuf, logs, sb_list) {
1422 		if (prev->sb_nextnum != segbuf->sb_nextnum) {
1423 			ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1424 			WARN_ON(ret); /* never fails */
1425 		}
1426 		if (atomic_read(&segbuf->sb_err) &&
1427 		    segbuf->sb_segnum != nilfs->ns_nextnum)
1428 			/* Case 2: extended segment (!= next) failed */
1429 			nilfs_sufile_set_error(sufile, segbuf->sb_segnum);
1430 		prev = segbuf;
1431 	}
1432 }
1433 
1434 static void nilfs_segctor_update_segusage(struct nilfs_sc_info *sci,
1435 					  struct inode *sufile)
1436 {
1437 	struct nilfs_segment_buffer *segbuf;
1438 	unsigned long live_blocks;
1439 	int ret;
1440 
1441 	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1442 		live_blocks = segbuf->sb_sum.nblocks +
1443 			(segbuf->sb_pseg_start - segbuf->sb_fseg_start);
1444 		ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1445 						     live_blocks,
1446 						     sci->sc_seg_ctime);
1447 		WARN_ON(ret); /* always succeed because the segusage is dirty */
1448 	}
1449 }
1450 
1451 static void nilfs_cancel_segusage(struct list_head *logs, struct inode *sufile)
1452 {
1453 	struct nilfs_segment_buffer *segbuf;
1454 	int ret;
1455 
1456 	segbuf = NILFS_FIRST_SEGBUF(logs);
1457 	ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1458 					     segbuf->sb_pseg_start -
1459 					     segbuf->sb_fseg_start, 0);
1460 	WARN_ON(ret); /* always succeed because the segusage is dirty */
1461 
1462 	list_for_each_entry_continue(segbuf, logs, sb_list) {
1463 		ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1464 						     0, 0);
1465 		WARN_ON(ret); /* always succeed */
1466 	}
1467 }
1468 
1469 static void nilfs_segctor_truncate_segments(struct nilfs_sc_info *sci,
1470 					    struct nilfs_segment_buffer *last,
1471 					    struct inode *sufile)
1472 {
1473 	struct nilfs_segment_buffer *segbuf = last;
1474 	int ret;
1475 
1476 	list_for_each_entry_continue(segbuf, &sci->sc_segbufs, sb_list) {
1477 		sci->sc_segbuf_nblocks -= segbuf->sb_rest_blocks;
1478 		ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1479 		WARN_ON(ret);
1480 	}
1481 	nilfs_truncate_logs(&sci->sc_segbufs, last);
1482 }
1483 
1484 
1485 static int nilfs_segctor_collect(struct nilfs_sc_info *sci,
1486 				 struct the_nilfs *nilfs, int mode)
1487 {
1488 	struct nilfs_cstage prev_stage = sci->sc_stage;
1489 	int err, nadd = 1;
1490 
1491 	/* Collection retry loop */
1492 	for (;;) {
1493 		sci->sc_super_root = NULL;
1494 		sci->sc_nblk_this_inc = 0;
1495 		sci->sc_curseg = NILFS_FIRST_SEGBUF(&sci->sc_segbufs);
1496 
1497 		err = nilfs_segctor_reset_segment_buffer(sci);
1498 		if (unlikely(err))
1499 			goto failed;
1500 
1501 		err = nilfs_segctor_collect_blocks(sci, mode);
1502 		sci->sc_nblk_this_inc += sci->sc_curseg->sb_sum.nblocks;
1503 		if (!err)
1504 			break;
1505 
1506 		if (unlikely(err != -E2BIG))
1507 			goto failed;
1508 
1509 		/* The current segment is filled up */
1510 		if (mode != SC_LSEG_SR || sci->sc_stage.scnt < NILFS_ST_CPFILE)
1511 			break;
1512 
1513 		if (sci->sc_stage.flags & NILFS_CF_SUFREED) {
1514 			err = nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1515 							sci->sc_freesegs,
1516 							sci->sc_nfreesegs,
1517 							NULL);
1518 			WARN_ON(err); /* do not happen */
1519 		}
1520 		nilfs_clear_logs(&sci->sc_segbufs);
1521 
1522 		err = nilfs_segctor_extend_segments(sci, nilfs, nadd);
1523 		if (unlikely(err))
1524 			return err;
1525 
1526 		nadd = min_t(int, nadd << 1, SC_MAX_SEGDELTA);
1527 		sci->sc_stage = prev_stage;
1528 	}
1529 	nilfs_segctor_truncate_segments(sci, sci->sc_curseg, nilfs->ns_sufile);
1530 	return 0;
1531 
1532  failed:
1533 	return err;
1534 }
1535 
1536 static void nilfs_list_replace_buffer(struct buffer_head *old_bh,
1537 				      struct buffer_head *new_bh)
1538 {
1539 	BUG_ON(!list_empty(&new_bh->b_assoc_buffers));
1540 
1541 	list_replace_init(&old_bh->b_assoc_buffers, &new_bh->b_assoc_buffers);
1542 	/* The caller must release old_bh */
1543 }
1544 
1545 static int
1546 nilfs_segctor_update_payload_blocknr(struct nilfs_sc_info *sci,
1547 				     struct nilfs_segment_buffer *segbuf,
1548 				     int mode)
1549 {
1550 	struct inode *inode = NULL;
1551 	sector_t blocknr;
1552 	unsigned long nfinfo = segbuf->sb_sum.nfinfo;
1553 	unsigned long nblocks = 0, ndatablk = 0;
1554 	struct nilfs_sc_operations *sc_op = NULL;
1555 	struct nilfs_segsum_pointer ssp;
1556 	struct nilfs_finfo *finfo = NULL;
1557 	union nilfs_binfo binfo;
1558 	struct buffer_head *bh, *bh_org;
1559 	ino_t ino = 0;
1560 	int err = 0;
1561 
1562 	if (!nfinfo)
1563 		goto out;
1564 
1565 	blocknr = segbuf->sb_pseg_start + segbuf->sb_sum.nsumblk;
1566 	ssp.bh = NILFS_SEGBUF_FIRST_BH(&segbuf->sb_segsum_buffers);
1567 	ssp.offset = sizeof(struct nilfs_segment_summary);
1568 
1569 	list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
1570 		if (bh == sci->sc_super_root)
1571 			break;
1572 		if (!finfo) {
1573 			finfo =	nilfs_segctor_map_segsum_entry(
1574 				sci, &ssp, sizeof(*finfo));
1575 			ino = le64_to_cpu(finfo->fi_ino);
1576 			nblocks = le32_to_cpu(finfo->fi_nblocks);
1577 			ndatablk = le32_to_cpu(finfo->fi_ndatablk);
1578 
1579 			if (buffer_nilfs_node(bh))
1580 				inode = NILFS_BTNC_I(bh->b_page->mapping);
1581 			else
1582 				inode = NILFS_AS_I(bh->b_page->mapping);
1583 
1584 			if (mode == SC_LSEG_DSYNC)
1585 				sc_op = &nilfs_sc_dsync_ops;
1586 			else if (ino == NILFS_DAT_INO)
1587 				sc_op = &nilfs_sc_dat_ops;
1588 			else /* file blocks */
1589 				sc_op = &nilfs_sc_file_ops;
1590 		}
1591 		bh_org = bh;
1592 		get_bh(bh_org);
1593 		err = nilfs_bmap_assign(NILFS_I(inode)->i_bmap, &bh, blocknr,
1594 					&binfo);
1595 		if (bh != bh_org)
1596 			nilfs_list_replace_buffer(bh_org, bh);
1597 		brelse(bh_org);
1598 		if (unlikely(err))
1599 			goto failed_bmap;
1600 
1601 		if (ndatablk > 0)
1602 			sc_op->write_data_binfo(sci, &ssp, &binfo);
1603 		else
1604 			sc_op->write_node_binfo(sci, &ssp, &binfo);
1605 
1606 		blocknr++;
1607 		if (--nblocks == 0) {
1608 			finfo = NULL;
1609 			if (--nfinfo == 0)
1610 				break;
1611 		} else if (ndatablk > 0)
1612 			ndatablk--;
1613 	}
1614  out:
1615 	return 0;
1616 
1617  failed_bmap:
1618 	err = nilfs_handle_bmap_error(err, __func__, inode, sci->sc_super);
1619 	return err;
1620 }
1621 
1622 static int nilfs_segctor_assign(struct nilfs_sc_info *sci, int mode)
1623 {
1624 	struct nilfs_segment_buffer *segbuf;
1625 	int err;
1626 
1627 	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1628 		err = nilfs_segctor_update_payload_blocknr(sci, segbuf, mode);
1629 		if (unlikely(err))
1630 			return err;
1631 		nilfs_segbuf_fill_in_segsum(segbuf);
1632 	}
1633 	return 0;
1634 }
1635 
1636 static int
1637 nilfs_copy_replace_page_buffers(struct page *page, struct list_head *out)
1638 {
1639 	struct page *clone_page;
1640 	struct buffer_head *bh, *head, *bh2;
1641 	void *kaddr;
1642 
1643 	bh = head = page_buffers(page);
1644 
1645 	clone_page = nilfs_alloc_private_page(bh->b_bdev, bh->b_size, 0);
1646 	if (unlikely(!clone_page))
1647 		return -ENOMEM;
1648 
1649 	bh2 = page_buffers(clone_page);
1650 	kaddr = kmap_atomic(page, KM_USER0);
1651 	do {
1652 		if (list_empty(&bh->b_assoc_buffers))
1653 			continue;
1654 		get_bh(bh2);
1655 		page_cache_get(clone_page); /* for each bh */
1656 		memcpy(bh2->b_data, kaddr + bh_offset(bh), bh2->b_size);
1657 		bh2->b_blocknr = bh->b_blocknr;
1658 		list_replace(&bh->b_assoc_buffers, &bh2->b_assoc_buffers);
1659 		list_add_tail(&bh->b_assoc_buffers, out);
1660 	} while (bh = bh->b_this_page, bh2 = bh2->b_this_page, bh != head);
1661 	kunmap_atomic(kaddr, KM_USER0);
1662 
1663 	if (!TestSetPageWriteback(clone_page))
1664 		inc_zone_page_state(clone_page, NR_WRITEBACK);
1665 	unlock_page(clone_page);
1666 
1667 	return 0;
1668 }
1669 
1670 static int nilfs_test_page_to_be_frozen(struct page *page)
1671 {
1672 	struct address_space *mapping = page->mapping;
1673 
1674 	if (!mapping || !mapping->host || S_ISDIR(mapping->host->i_mode))
1675 		return 0;
1676 
1677 	if (page_mapped(page)) {
1678 		ClearPageChecked(page);
1679 		return 1;
1680 	}
1681 	return PageChecked(page);
1682 }
1683 
1684 static int nilfs_begin_page_io(struct page *page, struct list_head *out)
1685 {
1686 	if (!page || PageWriteback(page))
1687 		/* For split b-tree node pages, this function may be called
1688 		   twice.  We ignore the 2nd or later calls by this check. */
1689 		return 0;
1690 
1691 	lock_page(page);
1692 	clear_page_dirty_for_io(page);
1693 	set_page_writeback(page);
1694 	unlock_page(page);
1695 
1696 	if (nilfs_test_page_to_be_frozen(page)) {
1697 		int err = nilfs_copy_replace_page_buffers(page, out);
1698 		if (unlikely(err))
1699 			return err;
1700 	}
1701 	return 0;
1702 }
1703 
1704 static int nilfs_segctor_prepare_write(struct nilfs_sc_info *sci,
1705 				       struct page **failed_page)
1706 {
1707 	struct nilfs_segment_buffer *segbuf;
1708 	struct page *bd_page = NULL, *fs_page = NULL;
1709 	struct list_head *list = &sci->sc_copied_buffers;
1710 	int err;
1711 
1712 	*failed_page = NULL;
1713 	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1714 		struct buffer_head *bh;
1715 
1716 		list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1717 				    b_assoc_buffers) {
1718 			if (bh->b_page != bd_page) {
1719 				if (bd_page) {
1720 					lock_page(bd_page);
1721 					clear_page_dirty_for_io(bd_page);
1722 					set_page_writeback(bd_page);
1723 					unlock_page(bd_page);
1724 				}
1725 				bd_page = bh->b_page;
1726 			}
1727 		}
1728 
1729 		list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1730 				    b_assoc_buffers) {
1731 			if (bh == sci->sc_super_root) {
1732 				if (bh->b_page != bd_page) {
1733 					lock_page(bd_page);
1734 					clear_page_dirty_for_io(bd_page);
1735 					set_page_writeback(bd_page);
1736 					unlock_page(bd_page);
1737 					bd_page = bh->b_page;
1738 				}
1739 				break;
1740 			}
1741 			if (bh->b_page != fs_page) {
1742 				err = nilfs_begin_page_io(fs_page, list);
1743 				if (unlikely(err)) {
1744 					*failed_page = fs_page;
1745 					goto out;
1746 				}
1747 				fs_page = bh->b_page;
1748 			}
1749 		}
1750 	}
1751 	if (bd_page) {
1752 		lock_page(bd_page);
1753 		clear_page_dirty_for_io(bd_page);
1754 		set_page_writeback(bd_page);
1755 		unlock_page(bd_page);
1756 	}
1757 	err = nilfs_begin_page_io(fs_page, list);
1758 	if (unlikely(err))
1759 		*failed_page = fs_page;
1760  out:
1761 	return err;
1762 }
1763 
1764 static int nilfs_segctor_write(struct nilfs_sc_info *sci,
1765 			       struct the_nilfs *nilfs)
1766 {
1767 	struct nilfs_segment_buffer *segbuf;
1768 	int ret = 0;
1769 
1770 	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1771 		ret = nilfs_segbuf_write(segbuf, nilfs);
1772 		if (ret)
1773 			break;
1774 	}
1775 	list_splice_tail_init(&sci->sc_segbufs, &sci->sc_write_logs);
1776 	return ret;
1777 }
1778 
1779 static void __nilfs_end_page_io(struct page *page, int err)
1780 {
1781 	if (!err) {
1782 		if (!nilfs_page_buffers_clean(page))
1783 			__set_page_dirty_nobuffers(page);
1784 		ClearPageError(page);
1785 	} else {
1786 		__set_page_dirty_nobuffers(page);
1787 		SetPageError(page);
1788 	}
1789 
1790 	if (buffer_nilfs_allocated(page_buffers(page))) {
1791 		if (TestClearPageWriteback(page))
1792 			dec_zone_page_state(page, NR_WRITEBACK);
1793 	} else
1794 		end_page_writeback(page);
1795 }
1796 
1797 static void nilfs_end_page_io(struct page *page, int err)
1798 {
1799 	if (!page)
1800 		return;
1801 
1802 	if (buffer_nilfs_node(page_buffers(page)) && !PageWriteback(page)) {
1803 		/*
1804 		 * For b-tree node pages, this function may be called twice
1805 		 * or more because they might be split in a segment.
1806 		 */
1807 		if (PageDirty(page)) {
1808 			/*
1809 			 * For pages holding split b-tree node buffers, dirty
1810 			 * flag on the buffers may be cleared discretely.
1811 			 * In that case, the page is once redirtied for
1812 			 * remaining buffers, and it must be cancelled if
1813 			 * all the buffers get cleaned later.
1814 			 */
1815 			lock_page(page);
1816 			if (nilfs_page_buffers_clean(page))
1817 				__nilfs_clear_page_dirty(page);
1818 			unlock_page(page);
1819 		}
1820 		return;
1821 	}
1822 
1823 	__nilfs_end_page_io(page, err);
1824 }
1825 
1826 static void nilfs_clear_copied_buffers(struct list_head *list, int err)
1827 {
1828 	struct buffer_head *bh, *head;
1829 	struct page *page;
1830 
1831 	while (!list_empty(list)) {
1832 		bh = list_entry(list->next, struct buffer_head,
1833 				b_assoc_buffers);
1834 		page = bh->b_page;
1835 		page_cache_get(page);
1836 		head = bh = page_buffers(page);
1837 		do {
1838 			if (!list_empty(&bh->b_assoc_buffers)) {
1839 				list_del_init(&bh->b_assoc_buffers);
1840 				if (!err) {
1841 					set_buffer_uptodate(bh);
1842 					clear_buffer_dirty(bh);
1843 					clear_buffer_nilfs_volatile(bh);
1844 				}
1845 				brelse(bh); /* for b_assoc_buffers */
1846 			}
1847 		} while ((bh = bh->b_this_page) != head);
1848 
1849 		__nilfs_end_page_io(page, err);
1850 		page_cache_release(page);
1851 	}
1852 }
1853 
1854 static void nilfs_abort_logs(struct list_head *logs, struct page *failed_page,
1855 			     struct buffer_head *bh_sr, int err)
1856 {
1857 	struct nilfs_segment_buffer *segbuf;
1858 	struct page *bd_page = NULL, *fs_page = NULL;
1859 	struct buffer_head *bh;
1860 
1861 	if (list_empty(logs))
1862 		return;
1863 
1864 	list_for_each_entry(segbuf, logs, sb_list) {
1865 		list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1866 				    b_assoc_buffers) {
1867 			if (bh->b_page != bd_page) {
1868 				if (bd_page)
1869 					end_page_writeback(bd_page);
1870 				bd_page = bh->b_page;
1871 			}
1872 		}
1873 
1874 		list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1875 				    b_assoc_buffers) {
1876 			if (bh == bh_sr) {
1877 				if (bh->b_page != bd_page) {
1878 					end_page_writeback(bd_page);
1879 					bd_page = bh->b_page;
1880 				}
1881 				break;
1882 			}
1883 			if (bh->b_page != fs_page) {
1884 				nilfs_end_page_io(fs_page, err);
1885 				if (fs_page && fs_page == failed_page)
1886 					return;
1887 				fs_page = bh->b_page;
1888 			}
1889 		}
1890 	}
1891 	if (bd_page)
1892 		end_page_writeback(bd_page);
1893 
1894 	nilfs_end_page_io(fs_page, err);
1895 }
1896 
1897 static void nilfs_segctor_abort_construction(struct nilfs_sc_info *sci,
1898 					     struct the_nilfs *nilfs, int err)
1899 {
1900 	LIST_HEAD(logs);
1901 	int ret;
1902 
1903 	list_splice_tail_init(&sci->sc_write_logs, &logs);
1904 	ret = nilfs_wait_on_logs(&logs);
1905 	if (ret)
1906 		nilfs_abort_logs(&logs, NULL, sci->sc_super_root, ret);
1907 
1908 	list_splice_tail_init(&sci->sc_segbufs, &logs);
1909 	nilfs_cancel_segusage(&logs, nilfs->ns_sufile);
1910 	nilfs_free_incomplete_logs(&logs, nilfs);
1911 	nilfs_clear_copied_buffers(&sci->sc_copied_buffers, err);
1912 
1913 	if (sci->sc_stage.flags & NILFS_CF_SUFREED) {
1914 		ret = nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1915 						sci->sc_freesegs,
1916 						sci->sc_nfreesegs,
1917 						NULL);
1918 		WARN_ON(ret); /* do not happen */
1919 	}
1920 
1921 	nilfs_destroy_logs(&logs);
1922 	sci->sc_super_root = NULL;
1923 }
1924 
1925 static void nilfs_set_next_segment(struct the_nilfs *nilfs,
1926 				   struct nilfs_segment_buffer *segbuf)
1927 {
1928 	nilfs->ns_segnum = segbuf->sb_segnum;
1929 	nilfs->ns_nextnum = segbuf->sb_nextnum;
1930 	nilfs->ns_pseg_offset = segbuf->sb_pseg_start - segbuf->sb_fseg_start
1931 		+ segbuf->sb_sum.nblocks;
1932 	nilfs->ns_seg_seq = segbuf->sb_sum.seg_seq;
1933 	nilfs->ns_ctime = segbuf->sb_sum.ctime;
1934 }
1935 
1936 static void nilfs_segctor_complete_write(struct nilfs_sc_info *sci)
1937 {
1938 	struct nilfs_segment_buffer *segbuf;
1939 	struct page *bd_page = NULL, *fs_page = NULL;
1940 	struct nilfs_sb_info *sbi = sci->sc_sbi;
1941 	struct the_nilfs *nilfs = sbi->s_nilfs;
1942 	int update_sr = (sci->sc_super_root != NULL);
1943 
1944 	list_for_each_entry(segbuf, &sci->sc_write_logs, sb_list) {
1945 		struct buffer_head *bh;
1946 
1947 		list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1948 				    b_assoc_buffers) {
1949 			set_buffer_uptodate(bh);
1950 			clear_buffer_dirty(bh);
1951 			if (bh->b_page != bd_page) {
1952 				if (bd_page)
1953 					end_page_writeback(bd_page);
1954 				bd_page = bh->b_page;
1955 			}
1956 		}
1957 		/*
1958 		 * We assume that the buffers which belong to the same page
1959 		 * continue over the buffer list.
1960 		 * Under this assumption, the last BHs of pages is
1961 		 * identifiable by the discontinuity of bh->b_page
1962 		 * (page != fs_page).
1963 		 *
1964 		 * For B-tree node blocks, however, this assumption is not
1965 		 * guaranteed.  The cleanup code of B-tree node pages needs
1966 		 * special care.
1967 		 */
1968 		list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1969 				    b_assoc_buffers) {
1970 			set_buffer_uptodate(bh);
1971 			clear_buffer_dirty(bh);
1972 			clear_buffer_nilfs_volatile(bh);
1973 			if (bh == sci->sc_super_root) {
1974 				if (bh->b_page != bd_page) {
1975 					end_page_writeback(bd_page);
1976 					bd_page = bh->b_page;
1977 				}
1978 				break;
1979 			}
1980 			if (bh->b_page != fs_page) {
1981 				nilfs_end_page_io(fs_page, 0);
1982 				fs_page = bh->b_page;
1983 			}
1984 		}
1985 
1986 		if (!NILFS_SEG_SIMPLEX(&segbuf->sb_sum)) {
1987 			if (NILFS_SEG_LOGBGN(&segbuf->sb_sum)) {
1988 				set_bit(NILFS_SC_UNCLOSED, &sci->sc_flags);
1989 				sci->sc_lseg_stime = jiffies;
1990 			}
1991 			if (NILFS_SEG_LOGEND(&segbuf->sb_sum))
1992 				clear_bit(NILFS_SC_UNCLOSED, &sci->sc_flags);
1993 		}
1994 	}
1995 	/*
1996 	 * Since pages may continue over multiple segment buffers,
1997 	 * end of the last page must be checked outside of the loop.
1998 	 */
1999 	if (bd_page)
2000 		end_page_writeback(bd_page);
2001 
2002 	nilfs_end_page_io(fs_page, 0);
2003 
2004 	nilfs_clear_copied_buffers(&sci->sc_copied_buffers, 0);
2005 
2006 	nilfs_drop_collected_inodes(&sci->sc_dirty_files);
2007 
2008 	if (nilfs_doing_gc()) {
2009 		nilfs_drop_collected_inodes(&sci->sc_gc_inodes);
2010 		if (update_sr)
2011 			nilfs_commit_gcdat_inode(nilfs);
2012 	} else
2013 		nilfs->ns_nongc_ctime = sci->sc_seg_ctime;
2014 
2015 	sci->sc_nblk_inc += sci->sc_nblk_this_inc;
2016 
2017 	segbuf = NILFS_LAST_SEGBUF(&sci->sc_write_logs);
2018 	nilfs_set_next_segment(nilfs, segbuf);
2019 
2020 	if (update_sr) {
2021 		nilfs_set_last_segment(nilfs, segbuf->sb_pseg_start,
2022 				       segbuf->sb_sum.seg_seq, nilfs->ns_cno++);
2023 		sbi->s_super->s_dirt = 1;
2024 
2025 		clear_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
2026 		clear_bit(NILFS_SC_DIRTY, &sci->sc_flags);
2027 		set_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags);
2028 		nilfs_segctor_clear_metadata_dirty(sci);
2029 	} else
2030 		clear_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags);
2031 }
2032 
2033 static int nilfs_segctor_wait(struct nilfs_sc_info *sci)
2034 {
2035 	int ret;
2036 
2037 	ret = nilfs_wait_on_logs(&sci->sc_write_logs);
2038 	if (!ret) {
2039 		nilfs_segctor_complete_write(sci);
2040 		nilfs_destroy_logs(&sci->sc_write_logs);
2041 	}
2042 	return ret;
2043 }
2044 
2045 static int nilfs_segctor_check_in_files(struct nilfs_sc_info *sci,
2046 					struct nilfs_sb_info *sbi)
2047 {
2048 	struct nilfs_inode_info *ii, *n;
2049 	__u64 cno = sbi->s_nilfs->ns_cno;
2050 
2051 	spin_lock(&sbi->s_inode_lock);
2052  retry:
2053 	list_for_each_entry_safe(ii, n, &sbi->s_dirty_files, i_dirty) {
2054 		if (!ii->i_bh) {
2055 			struct buffer_head *ibh;
2056 			int err;
2057 
2058 			spin_unlock(&sbi->s_inode_lock);
2059 			err = nilfs_ifile_get_inode_block(
2060 				sbi->s_ifile, ii->vfs_inode.i_ino, &ibh);
2061 			if (unlikely(err)) {
2062 				nilfs_warning(sbi->s_super, __func__,
2063 					      "failed to get inode block.\n");
2064 				return err;
2065 			}
2066 			nilfs_mdt_mark_buffer_dirty(ibh);
2067 			nilfs_mdt_mark_dirty(sbi->s_ifile);
2068 			spin_lock(&sbi->s_inode_lock);
2069 			if (likely(!ii->i_bh))
2070 				ii->i_bh = ibh;
2071 			else
2072 				brelse(ibh);
2073 			goto retry;
2074 		}
2075 		ii->i_cno = cno;
2076 
2077 		clear_bit(NILFS_I_QUEUED, &ii->i_state);
2078 		set_bit(NILFS_I_BUSY, &ii->i_state);
2079 		list_del(&ii->i_dirty);
2080 		list_add_tail(&ii->i_dirty, &sci->sc_dirty_files);
2081 	}
2082 	spin_unlock(&sbi->s_inode_lock);
2083 
2084 	NILFS_I(sbi->s_ifile)->i_cno = cno;
2085 
2086 	return 0;
2087 }
2088 
2089 static void nilfs_segctor_check_out_files(struct nilfs_sc_info *sci,
2090 					  struct nilfs_sb_info *sbi)
2091 {
2092 	struct nilfs_transaction_info *ti = current->journal_info;
2093 	struct nilfs_inode_info *ii, *n;
2094 	__u64 cno = sbi->s_nilfs->ns_cno;
2095 
2096 	spin_lock(&sbi->s_inode_lock);
2097 	list_for_each_entry_safe(ii, n, &sci->sc_dirty_files, i_dirty) {
2098 		if (!test_and_clear_bit(NILFS_I_UPDATED, &ii->i_state) ||
2099 		    test_bit(NILFS_I_DIRTY, &ii->i_state)) {
2100 			/* The current checkpoint number (=nilfs->ns_cno) is
2101 			   changed between check-in and check-out only if the
2102 			   super root is written out.  So, we can update i_cno
2103 			   for the inodes that remain in the dirty list. */
2104 			ii->i_cno = cno;
2105 			continue;
2106 		}
2107 		clear_bit(NILFS_I_BUSY, &ii->i_state);
2108 		brelse(ii->i_bh);
2109 		ii->i_bh = NULL;
2110 		list_del(&ii->i_dirty);
2111 		list_add_tail(&ii->i_dirty, &ti->ti_garbage);
2112 	}
2113 	spin_unlock(&sbi->s_inode_lock);
2114 }
2115 
2116 /*
2117  * Main procedure of segment constructor
2118  */
2119 static int nilfs_segctor_do_construct(struct nilfs_sc_info *sci, int mode)
2120 {
2121 	struct nilfs_sb_info *sbi = sci->sc_sbi;
2122 	struct the_nilfs *nilfs = sbi->s_nilfs;
2123 	struct page *failed_page;
2124 	int err, has_sr = 0;
2125 
2126 	sci->sc_stage.scnt = NILFS_ST_INIT;
2127 
2128 	err = nilfs_segctor_check_in_files(sci, sbi);
2129 	if (unlikely(err))
2130 		goto out;
2131 
2132 	if (nilfs_test_metadata_dirty(sbi))
2133 		set_bit(NILFS_SC_DIRTY, &sci->sc_flags);
2134 
2135 	if (nilfs_segctor_clean(sci))
2136 		goto out;
2137 
2138 	do {
2139 		sci->sc_stage.flags &= ~NILFS_CF_HISTORY_MASK;
2140 
2141 		err = nilfs_segctor_begin_construction(sci, nilfs);
2142 		if (unlikely(err))
2143 			goto out;
2144 
2145 		/* Update time stamp */
2146 		sci->sc_seg_ctime = get_seconds();
2147 
2148 		err = nilfs_segctor_collect(sci, nilfs, mode);
2149 		if (unlikely(err))
2150 			goto failed;
2151 
2152 		has_sr = (sci->sc_super_root != NULL);
2153 
2154 		/* Avoid empty segment */
2155 		if (sci->sc_stage.scnt == NILFS_ST_DONE &&
2156 		    NILFS_SEG_EMPTY(&sci->sc_curseg->sb_sum)) {
2157 			nilfs_segctor_abort_construction(sci, nilfs, 1);
2158 			goto out;
2159 		}
2160 
2161 		err = nilfs_segctor_assign(sci, mode);
2162 		if (unlikely(err))
2163 			goto failed;
2164 
2165 		if (sci->sc_stage.flags & NILFS_CF_IFILE_STARTED)
2166 			nilfs_segctor_fill_in_file_bmap(sci, sbi->s_ifile);
2167 
2168 		if (has_sr) {
2169 			err = nilfs_segctor_fill_in_checkpoint(sci);
2170 			if (unlikely(err))
2171 				goto failed_to_write;
2172 
2173 			nilfs_segctor_fill_in_super_root(sci, nilfs);
2174 		}
2175 		nilfs_segctor_update_segusage(sci, nilfs->ns_sufile);
2176 
2177 		/* Write partial segments */
2178 		err = nilfs_segctor_prepare_write(sci, &failed_page);
2179 		if (err) {
2180 			nilfs_abort_logs(&sci->sc_segbufs, failed_page,
2181 					 sci->sc_super_root, err);
2182 			goto failed_to_write;
2183 		}
2184 		nilfs_segctor_fill_in_checksums(sci, nilfs->ns_crc_seed);
2185 
2186 		err = nilfs_segctor_write(sci, nilfs);
2187 		if (unlikely(err))
2188 			goto failed_to_write;
2189 
2190 		if (sci->sc_stage.scnt == NILFS_ST_DONE ||
2191 		    nilfs->ns_blocksize_bits != PAGE_CACHE_SHIFT) {
2192 			/*
2193 			 * At this point, we avoid double buffering
2194 			 * for blocksize < pagesize because page dirty
2195 			 * flag is turned off during write and dirty
2196 			 * buffers are not properly collected for
2197 			 * pages crossing over segments.
2198 			 */
2199 			err = nilfs_segctor_wait(sci);
2200 			if (err)
2201 				goto failed_to_write;
2202 		}
2203 	} while (sci->sc_stage.scnt != NILFS_ST_DONE);
2204 
2205 	sci->sc_super_root = NULL;
2206 
2207  out:
2208 	nilfs_segctor_check_out_files(sci, sbi);
2209 	return err;
2210 
2211  failed_to_write:
2212 	if (sci->sc_stage.flags & NILFS_CF_IFILE_STARTED)
2213 		nilfs_redirty_inodes(&sci->sc_dirty_files);
2214 
2215  failed:
2216 	if (nilfs_doing_gc())
2217 		nilfs_redirty_inodes(&sci->sc_gc_inodes);
2218 	nilfs_segctor_abort_construction(sci, nilfs, err);
2219 	goto out;
2220 }
2221 
2222 /**
2223  * nilfs_secgtor_start_timer - set timer of background write
2224  * @sci: nilfs_sc_info
2225  *
2226  * If the timer has already been set, it ignores the new request.
2227  * This function MUST be called within a section locking the segment
2228  * semaphore.
2229  */
2230 static void nilfs_segctor_start_timer(struct nilfs_sc_info *sci)
2231 {
2232 	spin_lock(&sci->sc_state_lock);
2233 	if (sci->sc_timer && !(sci->sc_state & NILFS_SEGCTOR_COMMIT)) {
2234 		sci->sc_timer->expires = jiffies + sci->sc_interval;
2235 		add_timer(sci->sc_timer);
2236 		sci->sc_state |= NILFS_SEGCTOR_COMMIT;
2237 	}
2238 	spin_unlock(&sci->sc_state_lock);
2239 }
2240 
2241 static void nilfs_segctor_do_flush(struct nilfs_sc_info *sci, int bn)
2242 {
2243 	spin_lock(&sci->sc_state_lock);
2244 	if (!(sci->sc_flush_request & (1 << bn))) {
2245 		unsigned long prev_req = sci->sc_flush_request;
2246 
2247 		sci->sc_flush_request |= (1 << bn);
2248 		if (!prev_req)
2249 			wake_up(&sci->sc_wait_daemon);
2250 	}
2251 	spin_unlock(&sci->sc_state_lock);
2252 }
2253 
2254 /**
2255  * nilfs_flush_segment - trigger a segment construction for resource control
2256  * @sb: super block
2257  * @ino: inode number of the file to be flushed out.
2258  */
2259 void nilfs_flush_segment(struct super_block *sb, ino_t ino)
2260 {
2261 	struct nilfs_sb_info *sbi = NILFS_SB(sb);
2262 	struct nilfs_sc_info *sci = NILFS_SC(sbi);
2263 
2264 	if (!sci || nilfs_doing_construction())
2265 		return;
2266 	nilfs_segctor_do_flush(sci, NILFS_MDT_INODE(sb, ino) ? ino : 0);
2267 					/* assign bit 0 to data files */
2268 }
2269 
2270 struct nilfs_segctor_wait_request {
2271 	wait_queue_t	wq;
2272 	__u32		seq;
2273 	int		err;
2274 	atomic_t	done;
2275 };
2276 
2277 static int nilfs_segctor_sync(struct nilfs_sc_info *sci)
2278 {
2279 	struct nilfs_segctor_wait_request wait_req;
2280 	int err = 0;
2281 
2282 	spin_lock(&sci->sc_state_lock);
2283 	init_wait(&wait_req.wq);
2284 	wait_req.err = 0;
2285 	atomic_set(&wait_req.done, 0);
2286 	wait_req.seq = ++sci->sc_seq_request;
2287 	spin_unlock(&sci->sc_state_lock);
2288 
2289 	init_waitqueue_entry(&wait_req.wq, current);
2290 	add_wait_queue(&sci->sc_wait_request, &wait_req.wq);
2291 	set_current_state(TASK_INTERRUPTIBLE);
2292 	wake_up(&sci->sc_wait_daemon);
2293 
2294 	for (;;) {
2295 		if (atomic_read(&wait_req.done)) {
2296 			err = wait_req.err;
2297 			break;
2298 		}
2299 		if (!signal_pending(current)) {
2300 			schedule();
2301 			continue;
2302 		}
2303 		err = -ERESTARTSYS;
2304 		break;
2305 	}
2306 	finish_wait(&sci->sc_wait_request, &wait_req.wq);
2307 	return err;
2308 }
2309 
2310 static void nilfs_segctor_wakeup(struct nilfs_sc_info *sci, int err)
2311 {
2312 	struct nilfs_segctor_wait_request *wrq, *n;
2313 	unsigned long flags;
2314 
2315 	spin_lock_irqsave(&sci->sc_wait_request.lock, flags);
2316 	list_for_each_entry_safe(wrq, n, &sci->sc_wait_request.task_list,
2317 				 wq.task_list) {
2318 		if (!atomic_read(&wrq->done) &&
2319 		    nilfs_cnt32_ge(sci->sc_seq_done, wrq->seq)) {
2320 			wrq->err = err;
2321 			atomic_set(&wrq->done, 1);
2322 		}
2323 		if (atomic_read(&wrq->done)) {
2324 			wrq->wq.func(&wrq->wq,
2325 				     TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
2326 				     0, NULL);
2327 		}
2328 	}
2329 	spin_unlock_irqrestore(&sci->sc_wait_request.lock, flags);
2330 }
2331 
2332 /**
2333  * nilfs_construct_segment - construct a logical segment
2334  * @sb: super block
2335  *
2336  * Return Value: On success, 0 is retured. On errors, one of the following
2337  * negative error code is returned.
2338  *
2339  * %-EROFS - Read only filesystem.
2340  *
2341  * %-EIO - I/O error
2342  *
2343  * %-ENOSPC - No space left on device (only in a panic state).
2344  *
2345  * %-ERESTARTSYS - Interrupted.
2346  *
2347  * %-ENOMEM - Insufficient memory available.
2348  */
2349 int nilfs_construct_segment(struct super_block *sb)
2350 {
2351 	struct nilfs_sb_info *sbi = NILFS_SB(sb);
2352 	struct nilfs_sc_info *sci = NILFS_SC(sbi);
2353 	struct nilfs_transaction_info *ti;
2354 	int err;
2355 
2356 	if (!sci)
2357 		return -EROFS;
2358 
2359 	/* A call inside transactions causes a deadlock. */
2360 	BUG_ON((ti = current->journal_info) && ti->ti_magic == NILFS_TI_MAGIC);
2361 
2362 	err = nilfs_segctor_sync(sci);
2363 	return err;
2364 }
2365 
2366 /**
2367  * nilfs_construct_dsync_segment - construct a data-only logical segment
2368  * @sb: super block
2369  * @inode: inode whose data blocks should be written out
2370  * @start: start byte offset
2371  * @end: end byte offset (inclusive)
2372  *
2373  * Return Value: On success, 0 is retured. On errors, one of the following
2374  * negative error code is returned.
2375  *
2376  * %-EROFS - Read only filesystem.
2377  *
2378  * %-EIO - I/O error
2379  *
2380  * %-ENOSPC - No space left on device (only in a panic state).
2381  *
2382  * %-ERESTARTSYS - Interrupted.
2383  *
2384  * %-ENOMEM - Insufficient memory available.
2385  */
2386 int nilfs_construct_dsync_segment(struct super_block *sb, struct inode *inode,
2387 				  loff_t start, loff_t end)
2388 {
2389 	struct nilfs_sb_info *sbi = NILFS_SB(sb);
2390 	struct nilfs_sc_info *sci = NILFS_SC(sbi);
2391 	struct nilfs_inode_info *ii;
2392 	struct nilfs_transaction_info ti;
2393 	int err = 0;
2394 
2395 	if (!sci)
2396 		return -EROFS;
2397 
2398 	nilfs_transaction_lock(sbi, &ti, 0);
2399 
2400 	ii = NILFS_I(inode);
2401 	if (test_bit(NILFS_I_INODE_DIRTY, &ii->i_state) ||
2402 	    nilfs_test_opt(sbi, STRICT_ORDER) ||
2403 	    test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags) ||
2404 	    nilfs_discontinued(sbi->s_nilfs)) {
2405 		nilfs_transaction_unlock(sbi);
2406 		err = nilfs_segctor_sync(sci);
2407 		return err;
2408 	}
2409 
2410 	spin_lock(&sbi->s_inode_lock);
2411 	if (!test_bit(NILFS_I_QUEUED, &ii->i_state) &&
2412 	    !test_bit(NILFS_I_BUSY, &ii->i_state)) {
2413 		spin_unlock(&sbi->s_inode_lock);
2414 		nilfs_transaction_unlock(sbi);
2415 		return 0;
2416 	}
2417 	spin_unlock(&sbi->s_inode_lock);
2418 	sci->sc_dsync_inode = ii;
2419 	sci->sc_dsync_start = start;
2420 	sci->sc_dsync_end = end;
2421 
2422 	err = nilfs_segctor_do_construct(sci, SC_LSEG_DSYNC);
2423 
2424 	nilfs_transaction_unlock(sbi);
2425 	return err;
2426 }
2427 
2428 struct nilfs_segctor_req {
2429 	int mode;
2430 	__u32 seq_accepted;
2431 	int sc_err;  /* construction failure */
2432 	int sb_err;  /* super block writeback failure */
2433 };
2434 
2435 #define FLUSH_FILE_BIT	(0x1) /* data file only */
2436 #define FLUSH_DAT_BIT	(1 << NILFS_DAT_INO) /* DAT only */
2437 
2438 static void nilfs_segctor_accept(struct nilfs_sc_info *sci,
2439 				 struct nilfs_segctor_req *req)
2440 {
2441 	req->sc_err = req->sb_err = 0;
2442 	spin_lock(&sci->sc_state_lock);
2443 	req->seq_accepted = sci->sc_seq_request;
2444 	spin_unlock(&sci->sc_state_lock);
2445 
2446 	if (sci->sc_timer)
2447 		del_timer_sync(sci->sc_timer);
2448 }
2449 
2450 static void nilfs_segctor_notify(struct nilfs_sc_info *sci,
2451 				 struct nilfs_segctor_req *req)
2452 {
2453 	/* Clear requests (even when the construction failed) */
2454 	spin_lock(&sci->sc_state_lock);
2455 
2456 	if (req->mode == SC_LSEG_SR) {
2457 		sci->sc_state &= ~NILFS_SEGCTOR_COMMIT;
2458 		sci->sc_seq_done = req->seq_accepted;
2459 		nilfs_segctor_wakeup(sci, req->sc_err ? : req->sb_err);
2460 		sci->sc_flush_request = 0;
2461 	} else {
2462 		if (req->mode == SC_FLUSH_FILE)
2463 			sci->sc_flush_request &= ~FLUSH_FILE_BIT;
2464 		else if (req->mode == SC_FLUSH_DAT)
2465 			sci->sc_flush_request &= ~FLUSH_DAT_BIT;
2466 
2467 		/* re-enable timer if checkpoint creation was not done */
2468 		if (sci->sc_timer && (sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
2469 		    time_before(jiffies, sci->sc_timer->expires))
2470 			add_timer(sci->sc_timer);
2471 	}
2472 	spin_unlock(&sci->sc_state_lock);
2473 }
2474 
2475 static int nilfs_segctor_construct(struct nilfs_sc_info *sci,
2476 				   struct nilfs_segctor_req *req)
2477 {
2478 	struct nilfs_sb_info *sbi = sci->sc_sbi;
2479 	struct the_nilfs *nilfs = sbi->s_nilfs;
2480 	int err = 0;
2481 
2482 	if (nilfs_discontinued(nilfs))
2483 		req->mode = SC_LSEG_SR;
2484 	if (!nilfs_segctor_confirm(sci)) {
2485 		err = nilfs_segctor_do_construct(sci, req->mode);
2486 		req->sc_err = err;
2487 	}
2488 	if (likely(!err)) {
2489 		if (req->mode != SC_FLUSH_DAT)
2490 			atomic_set(&nilfs->ns_ndirtyblks, 0);
2491 		if (test_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags) &&
2492 		    nilfs_discontinued(nilfs)) {
2493 			down_write(&nilfs->ns_sem);
2494 			req->sb_err = nilfs_commit_super(sbi,
2495 					nilfs_altsb_need_update(nilfs));
2496 			up_write(&nilfs->ns_sem);
2497 		}
2498 	}
2499 	return err;
2500 }
2501 
2502 static void nilfs_construction_timeout(unsigned long data)
2503 {
2504 	struct task_struct *p = (struct task_struct *)data;
2505 	wake_up_process(p);
2506 }
2507 
2508 static void
2509 nilfs_remove_written_gcinodes(struct the_nilfs *nilfs, struct list_head *head)
2510 {
2511 	struct nilfs_inode_info *ii, *n;
2512 
2513 	list_for_each_entry_safe(ii, n, head, i_dirty) {
2514 		if (!test_bit(NILFS_I_UPDATED, &ii->i_state))
2515 			continue;
2516 		hlist_del_init(&ii->vfs_inode.i_hash);
2517 		list_del_init(&ii->i_dirty);
2518 		nilfs_clear_gcinode(&ii->vfs_inode);
2519 	}
2520 }
2521 
2522 int nilfs_clean_segments(struct super_block *sb, struct nilfs_argv *argv,
2523 			 void **kbufs)
2524 {
2525 	struct nilfs_sb_info *sbi = NILFS_SB(sb);
2526 	struct nilfs_sc_info *sci = NILFS_SC(sbi);
2527 	struct the_nilfs *nilfs = sbi->s_nilfs;
2528 	struct nilfs_transaction_info ti;
2529 	struct nilfs_segctor_req req = { .mode = SC_LSEG_SR };
2530 	int err;
2531 
2532 	if (unlikely(!sci))
2533 		return -EROFS;
2534 
2535 	nilfs_transaction_lock(sbi, &ti, 1);
2536 
2537 	err = nilfs_init_gcdat_inode(nilfs);
2538 	if (unlikely(err))
2539 		goto out_unlock;
2540 
2541 	err = nilfs_ioctl_prepare_clean_segments(nilfs, argv, kbufs);
2542 	if (unlikely(err))
2543 		goto out_unlock;
2544 
2545 	sci->sc_freesegs = kbufs[4];
2546 	sci->sc_nfreesegs = argv[4].v_nmembs;
2547 	list_splice_tail_init(&nilfs->ns_gc_inodes, &sci->sc_gc_inodes);
2548 
2549 	for (;;) {
2550 		nilfs_segctor_accept(sci, &req);
2551 		err = nilfs_segctor_construct(sci, &req);
2552 		nilfs_remove_written_gcinodes(nilfs, &sci->sc_gc_inodes);
2553 		nilfs_segctor_notify(sci, &req);
2554 
2555 		if (likely(!err))
2556 			break;
2557 
2558 		nilfs_warning(sb, __func__,
2559 			      "segment construction failed. (err=%d)", err);
2560 		set_current_state(TASK_INTERRUPTIBLE);
2561 		schedule_timeout(sci->sc_interval);
2562 	}
2563 
2564  out_unlock:
2565 	sci->sc_freesegs = NULL;
2566 	sci->sc_nfreesegs = 0;
2567 	nilfs_clear_gcdat_inode(nilfs);
2568 	nilfs_transaction_unlock(sbi);
2569 	return err;
2570 }
2571 
2572 static void nilfs_segctor_thread_construct(struct nilfs_sc_info *sci, int mode)
2573 {
2574 	struct nilfs_sb_info *sbi = sci->sc_sbi;
2575 	struct nilfs_transaction_info ti;
2576 	struct nilfs_segctor_req req = { .mode = mode };
2577 
2578 	nilfs_transaction_lock(sbi, &ti, 0);
2579 
2580 	nilfs_segctor_accept(sci, &req);
2581 	nilfs_segctor_construct(sci, &req);
2582 	nilfs_segctor_notify(sci, &req);
2583 
2584 	/*
2585 	 * Unclosed segment should be retried.  We do this using sc_timer.
2586 	 * Timeout of sc_timer will invoke complete construction which leads
2587 	 * to close the current logical segment.
2588 	 */
2589 	if (test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags))
2590 		nilfs_segctor_start_timer(sci);
2591 
2592 	nilfs_transaction_unlock(sbi);
2593 }
2594 
2595 static void nilfs_segctor_do_immediate_flush(struct nilfs_sc_info *sci)
2596 {
2597 	int mode = 0;
2598 	int err;
2599 
2600 	spin_lock(&sci->sc_state_lock);
2601 	mode = (sci->sc_flush_request & FLUSH_DAT_BIT) ?
2602 		SC_FLUSH_DAT : SC_FLUSH_FILE;
2603 	spin_unlock(&sci->sc_state_lock);
2604 
2605 	if (mode) {
2606 		err = nilfs_segctor_do_construct(sci, mode);
2607 
2608 		spin_lock(&sci->sc_state_lock);
2609 		sci->sc_flush_request &= (mode == SC_FLUSH_FILE) ?
2610 			~FLUSH_FILE_BIT : ~FLUSH_DAT_BIT;
2611 		spin_unlock(&sci->sc_state_lock);
2612 	}
2613 	clear_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags);
2614 }
2615 
2616 static int nilfs_segctor_flush_mode(struct nilfs_sc_info *sci)
2617 {
2618 	if (!test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags) ||
2619 	    time_before(jiffies, sci->sc_lseg_stime + sci->sc_mjcp_freq)) {
2620 		if (!(sci->sc_flush_request & ~FLUSH_FILE_BIT))
2621 			return SC_FLUSH_FILE;
2622 		else if (!(sci->sc_flush_request & ~FLUSH_DAT_BIT))
2623 			return SC_FLUSH_DAT;
2624 	}
2625 	return SC_LSEG_SR;
2626 }
2627 
2628 /**
2629  * nilfs_segctor_thread - main loop of the segment constructor thread.
2630  * @arg: pointer to a struct nilfs_sc_info.
2631  *
2632  * nilfs_segctor_thread() initializes a timer and serves as a daemon
2633  * to execute segment constructions.
2634  */
2635 static int nilfs_segctor_thread(void *arg)
2636 {
2637 	struct nilfs_sc_info *sci = (struct nilfs_sc_info *)arg;
2638 	struct timer_list timer;
2639 	int timeout = 0;
2640 
2641 	init_timer(&timer);
2642 	timer.data = (unsigned long)current;
2643 	timer.function = nilfs_construction_timeout;
2644 	sci->sc_timer = &timer;
2645 
2646 	/* start sync. */
2647 	sci->sc_task = current;
2648 	wake_up(&sci->sc_wait_task); /* for nilfs_segctor_start_thread() */
2649 	printk(KERN_INFO
2650 	       "segctord starting. Construction interval = %lu seconds, "
2651 	       "CP frequency < %lu seconds\n",
2652 	       sci->sc_interval / HZ, sci->sc_mjcp_freq / HZ);
2653 
2654 	spin_lock(&sci->sc_state_lock);
2655  loop:
2656 	for (;;) {
2657 		int mode;
2658 
2659 		if (sci->sc_state & NILFS_SEGCTOR_QUIT)
2660 			goto end_thread;
2661 
2662 		if (timeout || sci->sc_seq_request != sci->sc_seq_done)
2663 			mode = SC_LSEG_SR;
2664 		else if (!sci->sc_flush_request)
2665 			break;
2666 		else
2667 			mode = nilfs_segctor_flush_mode(sci);
2668 
2669 		spin_unlock(&sci->sc_state_lock);
2670 		nilfs_segctor_thread_construct(sci, mode);
2671 		spin_lock(&sci->sc_state_lock);
2672 		timeout = 0;
2673 	}
2674 
2675 
2676 	if (freezing(current)) {
2677 		spin_unlock(&sci->sc_state_lock);
2678 		refrigerator();
2679 		spin_lock(&sci->sc_state_lock);
2680 	} else {
2681 		DEFINE_WAIT(wait);
2682 		int should_sleep = 1;
2683 		struct the_nilfs *nilfs;
2684 
2685 		prepare_to_wait(&sci->sc_wait_daemon, &wait,
2686 				TASK_INTERRUPTIBLE);
2687 
2688 		if (sci->sc_seq_request != sci->sc_seq_done)
2689 			should_sleep = 0;
2690 		else if (sci->sc_flush_request)
2691 			should_sleep = 0;
2692 		else if (sci->sc_state & NILFS_SEGCTOR_COMMIT)
2693 			should_sleep = time_before(jiffies,
2694 						   sci->sc_timer->expires);
2695 
2696 		if (should_sleep) {
2697 			spin_unlock(&sci->sc_state_lock);
2698 			schedule();
2699 			spin_lock(&sci->sc_state_lock);
2700 		}
2701 		finish_wait(&sci->sc_wait_daemon, &wait);
2702 		timeout = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
2703 			   time_after_eq(jiffies, sci->sc_timer->expires));
2704 		nilfs = sci->sc_sbi->s_nilfs;
2705 		if (sci->sc_super->s_dirt && nilfs_sb_need_update(nilfs))
2706 			set_nilfs_discontinued(nilfs);
2707 	}
2708 	goto loop;
2709 
2710  end_thread:
2711 	spin_unlock(&sci->sc_state_lock);
2712 	del_timer_sync(sci->sc_timer);
2713 	sci->sc_timer = NULL;
2714 
2715 	/* end sync. */
2716 	sci->sc_task = NULL;
2717 	wake_up(&sci->sc_wait_task); /* for nilfs_segctor_kill_thread() */
2718 	return 0;
2719 }
2720 
2721 static int nilfs_segctor_start_thread(struct nilfs_sc_info *sci)
2722 {
2723 	struct task_struct *t;
2724 
2725 	t = kthread_run(nilfs_segctor_thread, sci, "segctord");
2726 	if (IS_ERR(t)) {
2727 		int err = PTR_ERR(t);
2728 
2729 		printk(KERN_ERR "NILFS: error %d creating segctord thread\n",
2730 		       err);
2731 		return err;
2732 	}
2733 	wait_event(sci->sc_wait_task, sci->sc_task != NULL);
2734 	return 0;
2735 }
2736 
2737 static void nilfs_segctor_kill_thread(struct nilfs_sc_info *sci)
2738 {
2739 	sci->sc_state |= NILFS_SEGCTOR_QUIT;
2740 
2741 	while (sci->sc_task) {
2742 		wake_up(&sci->sc_wait_daemon);
2743 		spin_unlock(&sci->sc_state_lock);
2744 		wait_event(sci->sc_wait_task, sci->sc_task == NULL);
2745 		spin_lock(&sci->sc_state_lock);
2746 	}
2747 }
2748 
2749 static int nilfs_segctor_init(struct nilfs_sc_info *sci)
2750 {
2751 	sci->sc_seq_done = sci->sc_seq_request;
2752 
2753 	return nilfs_segctor_start_thread(sci);
2754 }
2755 
2756 /*
2757  * Setup & clean-up functions
2758  */
2759 static struct nilfs_sc_info *nilfs_segctor_new(struct nilfs_sb_info *sbi)
2760 {
2761 	struct nilfs_sc_info *sci;
2762 
2763 	sci = kzalloc(sizeof(*sci), GFP_KERNEL);
2764 	if (!sci)
2765 		return NULL;
2766 
2767 	sci->sc_sbi = sbi;
2768 	sci->sc_super = sbi->s_super;
2769 
2770 	init_waitqueue_head(&sci->sc_wait_request);
2771 	init_waitqueue_head(&sci->sc_wait_daemon);
2772 	init_waitqueue_head(&sci->sc_wait_task);
2773 	spin_lock_init(&sci->sc_state_lock);
2774 	INIT_LIST_HEAD(&sci->sc_dirty_files);
2775 	INIT_LIST_HEAD(&sci->sc_segbufs);
2776 	INIT_LIST_HEAD(&sci->sc_write_logs);
2777 	INIT_LIST_HEAD(&sci->sc_gc_inodes);
2778 	INIT_LIST_HEAD(&sci->sc_copied_buffers);
2779 
2780 	sci->sc_interval = HZ * NILFS_SC_DEFAULT_TIMEOUT;
2781 	sci->sc_mjcp_freq = HZ * NILFS_SC_DEFAULT_SR_FREQ;
2782 	sci->sc_watermark = NILFS_SC_DEFAULT_WATERMARK;
2783 
2784 	if (sbi->s_interval)
2785 		sci->sc_interval = sbi->s_interval;
2786 	if (sbi->s_watermark)
2787 		sci->sc_watermark = sbi->s_watermark;
2788 	return sci;
2789 }
2790 
2791 static void nilfs_segctor_write_out(struct nilfs_sc_info *sci)
2792 {
2793 	int ret, retrycount = NILFS_SC_CLEANUP_RETRY;
2794 
2795 	/* The segctord thread was stopped and its timer was removed.
2796 	   But some tasks remain. */
2797 	do {
2798 		struct nilfs_sb_info *sbi = sci->sc_sbi;
2799 		struct nilfs_transaction_info ti;
2800 		struct nilfs_segctor_req req = { .mode = SC_LSEG_SR };
2801 
2802 		nilfs_transaction_lock(sbi, &ti, 0);
2803 		nilfs_segctor_accept(sci, &req);
2804 		ret = nilfs_segctor_construct(sci, &req);
2805 		nilfs_segctor_notify(sci, &req);
2806 		nilfs_transaction_unlock(sbi);
2807 
2808 	} while (ret && retrycount-- > 0);
2809 }
2810 
2811 /**
2812  * nilfs_segctor_destroy - destroy the segment constructor.
2813  * @sci: nilfs_sc_info
2814  *
2815  * nilfs_segctor_destroy() kills the segctord thread and frees
2816  * the nilfs_sc_info struct.
2817  * Caller must hold the segment semaphore.
2818  */
2819 static void nilfs_segctor_destroy(struct nilfs_sc_info *sci)
2820 {
2821 	struct nilfs_sb_info *sbi = sci->sc_sbi;
2822 	int flag;
2823 
2824 	up_write(&sbi->s_nilfs->ns_segctor_sem);
2825 
2826 	spin_lock(&sci->sc_state_lock);
2827 	nilfs_segctor_kill_thread(sci);
2828 	flag = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) || sci->sc_flush_request
2829 		|| sci->sc_seq_request != sci->sc_seq_done);
2830 	spin_unlock(&sci->sc_state_lock);
2831 
2832 	if (flag || nilfs_segctor_confirm(sci))
2833 		nilfs_segctor_write_out(sci);
2834 
2835 	WARN_ON(!list_empty(&sci->sc_copied_buffers));
2836 
2837 	if (!list_empty(&sci->sc_dirty_files)) {
2838 		nilfs_warning(sbi->s_super, __func__,
2839 			      "dirty file(s) after the final construction\n");
2840 		nilfs_dispose_list(sbi, &sci->sc_dirty_files, 1);
2841 	}
2842 
2843 	WARN_ON(!list_empty(&sci->sc_segbufs));
2844 	WARN_ON(!list_empty(&sci->sc_write_logs));
2845 
2846 	down_write(&sbi->s_nilfs->ns_segctor_sem);
2847 
2848 	kfree(sci);
2849 }
2850 
2851 /**
2852  * nilfs_attach_segment_constructor - attach a segment constructor
2853  * @sbi: nilfs_sb_info
2854  *
2855  * nilfs_attach_segment_constructor() allocates a struct nilfs_sc_info,
2856  * initilizes it, and starts the segment constructor.
2857  *
2858  * Return Value: On success, 0 is returned. On error, one of the following
2859  * negative error code is returned.
2860  *
2861  * %-ENOMEM - Insufficient memory available.
2862  */
2863 int nilfs_attach_segment_constructor(struct nilfs_sb_info *sbi)
2864 {
2865 	struct the_nilfs *nilfs = sbi->s_nilfs;
2866 	int err;
2867 
2868 	/* Each field of nilfs_segctor is cleared through the initialization
2869 	   of super-block info */
2870 	sbi->s_sc_info = nilfs_segctor_new(sbi);
2871 	if (!sbi->s_sc_info)
2872 		return -ENOMEM;
2873 
2874 	nilfs_attach_writer(nilfs, sbi);
2875 	err = nilfs_segctor_init(NILFS_SC(sbi));
2876 	if (err) {
2877 		nilfs_detach_writer(nilfs, sbi);
2878 		kfree(sbi->s_sc_info);
2879 		sbi->s_sc_info = NULL;
2880 	}
2881 	return err;
2882 }
2883 
2884 /**
2885  * nilfs_detach_segment_constructor - destroy the segment constructor
2886  * @sbi: nilfs_sb_info
2887  *
2888  * nilfs_detach_segment_constructor() kills the segment constructor daemon,
2889  * frees the struct nilfs_sc_info, and destroy the dirty file list.
2890  */
2891 void nilfs_detach_segment_constructor(struct nilfs_sb_info *sbi)
2892 {
2893 	struct the_nilfs *nilfs = sbi->s_nilfs;
2894 	LIST_HEAD(garbage_list);
2895 
2896 	down_write(&nilfs->ns_segctor_sem);
2897 	if (NILFS_SC(sbi)) {
2898 		nilfs_segctor_destroy(NILFS_SC(sbi));
2899 		sbi->s_sc_info = NULL;
2900 	}
2901 
2902 	/* Force to free the list of dirty files */
2903 	spin_lock(&sbi->s_inode_lock);
2904 	if (!list_empty(&sbi->s_dirty_files)) {
2905 		list_splice_init(&sbi->s_dirty_files, &garbage_list);
2906 		nilfs_warning(sbi->s_super, __func__,
2907 			      "Non empty dirty list after the last "
2908 			      "segment construction\n");
2909 	}
2910 	spin_unlock(&sbi->s_inode_lock);
2911 	up_write(&nilfs->ns_segctor_sem);
2912 
2913 	nilfs_dispose_list(sbi, &garbage_list, 1);
2914 	nilfs_detach_writer(nilfs, sbi);
2915 }
2916