xref: /linux/fs/nilfs2/segment.c (revision 0678df8271820bcf8fb4f877129f05d68a237de4)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * NILFS segment constructor.
4  *
5  * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
6  *
7  * Written by Ryusuke Konishi.
8  *
9  */
10 
11 #include <linux/pagemap.h>
12 #include <linux/buffer_head.h>
13 #include <linux/writeback.h>
14 #include <linux/bitops.h>
15 #include <linux/bio.h>
16 #include <linux/completion.h>
17 #include <linux/blkdev.h>
18 #include <linux/backing-dev.h>
19 #include <linux/freezer.h>
20 #include <linux/kthread.h>
21 #include <linux/crc32.h>
22 #include <linux/pagevec.h>
23 #include <linux/slab.h>
24 #include <linux/sched/signal.h>
25 
26 #include "nilfs.h"
27 #include "btnode.h"
28 #include "page.h"
29 #include "segment.h"
30 #include "sufile.h"
31 #include "cpfile.h"
32 #include "ifile.h"
33 #include "segbuf.h"
34 
35 
36 /*
37  * Segment constructor
38  */
39 #define SC_N_INODEVEC	16   /* Size of locally allocated inode vector */
40 
41 #define SC_MAX_SEGDELTA 64   /*
42 			      * Upper limit of the number of segments
43 			      * appended in collection retry loop
44 			      */
45 
46 /* Construction mode */
47 enum {
48 	SC_LSEG_SR = 1,	/* Make a logical segment having a super root */
49 	SC_LSEG_DSYNC,	/*
50 			 * Flush data blocks of a given file and make
51 			 * a logical segment without a super root.
52 			 */
53 	SC_FLUSH_FILE,	/*
54 			 * Flush data files, leads to segment writes without
55 			 * creating a checkpoint.
56 			 */
57 	SC_FLUSH_DAT,	/*
58 			 * Flush DAT file.  This also creates segments
59 			 * without a checkpoint.
60 			 */
61 };
62 
63 /* Stage numbers of dirty block collection */
64 enum {
65 	NILFS_ST_INIT = 0,
66 	NILFS_ST_GC,		/* Collecting dirty blocks for GC */
67 	NILFS_ST_FILE,
68 	NILFS_ST_IFILE,
69 	NILFS_ST_CPFILE,
70 	NILFS_ST_SUFILE,
71 	NILFS_ST_DAT,
72 	NILFS_ST_SR,		/* Super root */
73 	NILFS_ST_DSYNC,		/* Data sync blocks */
74 	NILFS_ST_DONE,
75 };
76 
77 #define CREATE_TRACE_POINTS
78 #include <trace/events/nilfs2.h>
79 
80 /*
81  * nilfs_sc_cstage_inc(), nilfs_sc_cstage_set(), nilfs_sc_cstage_get() are
82  * wrapper functions of stage count (nilfs_sc_info->sc_stage.scnt). Users of
83  * the variable must use them because transition of stage count must involve
84  * trace events (trace_nilfs2_collection_stage_transition).
85  *
86  * nilfs_sc_cstage_get() isn't required for the above purpose because it doesn't
87  * produce tracepoint events. It is provided just for making the intention
88  * clear.
89  */
90 static inline void nilfs_sc_cstage_inc(struct nilfs_sc_info *sci)
91 {
92 	sci->sc_stage.scnt++;
93 	trace_nilfs2_collection_stage_transition(sci);
94 }
95 
96 static inline void nilfs_sc_cstage_set(struct nilfs_sc_info *sci, int next_scnt)
97 {
98 	sci->sc_stage.scnt = next_scnt;
99 	trace_nilfs2_collection_stage_transition(sci);
100 }
101 
102 static inline int nilfs_sc_cstage_get(struct nilfs_sc_info *sci)
103 {
104 	return sci->sc_stage.scnt;
105 }
106 
107 /* State flags of collection */
108 #define NILFS_CF_NODE		0x0001	/* Collecting node blocks */
109 #define NILFS_CF_IFILE_STARTED	0x0002	/* IFILE stage has started */
110 #define NILFS_CF_SUFREED	0x0004	/* segment usages has been freed */
111 #define NILFS_CF_HISTORY_MASK	(NILFS_CF_IFILE_STARTED | NILFS_CF_SUFREED)
112 
113 /* Operations depending on the construction mode and file type */
114 struct nilfs_sc_operations {
115 	int (*collect_data)(struct nilfs_sc_info *, struct buffer_head *,
116 			    struct inode *);
117 	int (*collect_node)(struct nilfs_sc_info *, struct buffer_head *,
118 			    struct inode *);
119 	int (*collect_bmap)(struct nilfs_sc_info *, struct buffer_head *,
120 			    struct inode *);
121 	void (*write_data_binfo)(struct nilfs_sc_info *,
122 				 struct nilfs_segsum_pointer *,
123 				 union nilfs_binfo *);
124 	void (*write_node_binfo)(struct nilfs_sc_info *,
125 				 struct nilfs_segsum_pointer *,
126 				 union nilfs_binfo *);
127 };
128 
129 /*
130  * Other definitions
131  */
132 static void nilfs_segctor_start_timer(struct nilfs_sc_info *);
133 static void nilfs_segctor_do_flush(struct nilfs_sc_info *, int);
134 static void nilfs_segctor_do_immediate_flush(struct nilfs_sc_info *);
135 static void nilfs_dispose_list(struct the_nilfs *, struct list_head *, int);
136 
137 #define nilfs_cnt32_ge(a, b)   \
138 	(typecheck(__u32, a) && typecheck(__u32, b) && \
139 	 ((__s32)(a) - (__s32)(b) >= 0))
140 
141 static int nilfs_prepare_segment_lock(struct super_block *sb,
142 				      struct nilfs_transaction_info *ti)
143 {
144 	struct nilfs_transaction_info *cur_ti = current->journal_info;
145 	void *save = NULL;
146 
147 	if (cur_ti) {
148 		if (cur_ti->ti_magic == NILFS_TI_MAGIC)
149 			return ++cur_ti->ti_count;
150 
151 		/*
152 		 * If journal_info field is occupied by other FS,
153 		 * it is saved and will be restored on
154 		 * nilfs_transaction_commit().
155 		 */
156 		nilfs_warn(sb, "journal info from a different FS");
157 		save = current->journal_info;
158 	}
159 	if (!ti) {
160 		ti = kmem_cache_alloc(nilfs_transaction_cachep, GFP_NOFS);
161 		if (!ti)
162 			return -ENOMEM;
163 		ti->ti_flags = NILFS_TI_DYNAMIC_ALLOC;
164 	} else {
165 		ti->ti_flags = 0;
166 	}
167 	ti->ti_count = 0;
168 	ti->ti_save = save;
169 	ti->ti_magic = NILFS_TI_MAGIC;
170 	current->journal_info = ti;
171 	return 0;
172 }
173 
174 /**
175  * nilfs_transaction_begin - start indivisible file operations.
176  * @sb: super block
177  * @ti: nilfs_transaction_info
178  * @vacancy_check: flags for vacancy rate checks
179  *
180  * nilfs_transaction_begin() acquires a reader/writer semaphore, called
181  * the segment semaphore, to make a segment construction and write tasks
182  * exclusive.  The function is used with nilfs_transaction_commit() in pairs.
183  * The region enclosed by these two functions can be nested.  To avoid a
184  * deadlock, the semaphore is only acquired or released in the outermost call.
185  *
186  * This function allocates a nilfs_transaction_info struct to keep context
187  * information on it.  It is initialized and hooked onto the current task in
188  * the outermost call.  If a pre-allocated struct is given to @ti, it is used
189  * instead; otherwise a new struct is assigned from a slab.
190  *
191  * When @vacancy_check flag is set, this function will check the amount of
192  * free space, and will wait for the GC to reclaim disk space if low capacity.
193  *
194  * Return Value: On success, 0 is returned. On error, one of the following
195  * negative error code is returned.
196  *
197  * %-ENOMEM - Insufficient memory available.
198  *
199  * %-ENOSPC - No space left on device
200  */
201 int nilfs_transaction_begin(struct super_block *sb,
202 			    struct nilfs_transaction_info *ti,
203 			    int vacancy_check)
204 {
205 	struct the_nilfs *nilfs;
206 	int ret = nilfs_prepare_segment_lock(sb, ti);
207 	struct nilfs_transaction_info *trace_ti;
208 
209 	if (unlikely(ret < 0))
210 		return ret;
211 	if (ret > 0) {
212 		trace_ti = current->journal_info;
213 
214 		trace_nilfs2_transaction_transition(sb, trace_ti,
215 				    trace_ti->ti_count, trace_ti->ti_flags,
216 				    TRACE_NILFS2_TRANSACTION_BEGIN);
217 		return 0;
218 	}
219 
220 	sb_start_intwrite(sb);
221 
222 	nilfs = sb->s_fs_info;
223 	down_read(&nilfs->ns_segctor_sem);
224 	if (vacancy_check && nilfs_near_disk_full(nilfs)) {
225 		up_read(&nilfs->ns_segctor_sem);
226 		ret = -ENOSPC;
227 		goto failed;
228 	}
229 
230 	trace_ti = current->journal_info;
231 	trace_nilfs2_transaction_transition(sb, trace_ti, trace_ti->ti_count,
232 					    trace_ti->ti_flags,
233 					    TRACE_NILFS2_TRANSACTION_BEGIN);
234 	return 0;
235 
236  failed:
237 	ti = current->journal_info;
238 	current->journal_info = ti->ti_save;
239 	if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
240 		kmem_cache_free(nilfs_transaction_cachep, ti);
241 	sb_end_intwrite(sb);
242 	return ret;
243 }
244 
245 /**
246  * nilfs_transaction_commit - commit indivisible file operations.
247  * @sb: super block
248  *
249  * nilfs_transaction_commit() releases the read semaphore which is
250  * acquired by nilfs_transaction_begin(). This is only performed
251  * in outermost call of this function.  If a commit flag is set,
252  * nilfs_transaction_commit() sets a timer to start the segment
253  * constructor.  If a sync flag is set, it starts construction
254  * directly.
255  */
256 int nilfs_transaction_commit(struct super_block *sb)
257 {
258 	struct nilfs_transaction_info *ti = current->journal_info;
259 	struct the_nilfs *nilfs = sb->s_fs_info;
260 	int err = 0;
261 
262 	BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
263 	ti->ti_flags |= NILFS_TI_COMMIT;
264 	if (ti->ti_count > 0) {
265 		ti->ti_count--;
266 		trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
267 			    ti->ti_flags, TRACE_NILFS2_TRANSACTION_COMMIT);
268 		return 0;
269 	}
270 	if (nilfs->ns_writer) {
271 		struct nilfs_sc_info *sci = nilfs->ns_writer;
272 
273 		if (ti->ti_flags & NILFS_TI_COMMIT)
274 			nilfs_segctor_start_timer(sci);
275 		if (atomic_read(&nilfs->ns_ndirtyblks) > sci->sc_watermark)
276 			nilfs_segctor_do_flush(sci, 0);
277 	}
278 	up_read(&nilfs->ns_segctor_sem);
279 	trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
280 			    ti->ti_flags, TRACE_NILFS2_TRANSACTION_COMMIT);
281 
282 	current->journal_info = ti->ti_save;
283 
284 	if (ti->ti_flags & NILFS_TI_SYNC)
285 		err = nilfs_construct_segment(sb);
286 	if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
287 		kmem_cache_free(nilfs_transaction_cachep, ti);
288 	sb_end_intwrite(sb);
289 	return err;
290 }
291 
292 void nilfs_transaction_abort(struct super_block *sb)
293 {
294 	struct nilfs_transaction_info *ti = current->journal_info;
295 	struct the_nilfs *nilfs = sb->s_fs_info;
296 
297 	BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
298 	if (ti->ti_count > 0) {
299 		ti->ti_count--;
300 		trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
301 			    ti->ti_flags, TRACE_NILFS2_TRANSACTION_ABORT);
302 		return;
303 	}
304 	up_read(&nilfs->ns_segctor_sem);
305 
306 	trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
307 		    ti->ti_flags, TRACE_NILFS2_TRANSACTION_ABORT);
308 
309 	current->journal_info = ti->ti_save;
310 	if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
311 		kmem_cache_free(nilfs_transaction_cachep, ti);
312 	sb_end_intwrite(sb);
313 }
314 
315 void nilfs_relax_pressure_in_lock(struct super_block *sb)
316 {
317 	struct the_nilfs *nilfs = sb->s_fs_info;
318 	struct nilfs_sc_info *sci = nilfs->ns_writer;
319 
320 	if (sb_rdonly(sb) || unlikely(!sci) || !sci->sc_flush_request)
321 		return;
322 
323 	set_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags);
324 	up_read(&nilfs->ns_segctor_sem);
325 
326 	down_write(&nilfs->ns_segctor_sem);
327 	if (sci->sc_flush_request &&
328 	    test_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags)) {
329 		struct nilfs_transaction_info *ti = current->journal_info;
330 
331 		ti->ti_flags |= NILFS_TI_WRITER;
332 		nilfs_segctor_do_immediate_flush(sci);
333 		ti->ti_flags &= ~NILFS_TI_WRITER;
334 	}
335 	downgrade_write(&nilfs->ns_segctor_sem);
336 }
337 
338 static void nilfs_transaction_lock(struct super_block *sb,
339 				   struct nilfs_transaction_info *ti,
340 				   int gcflag)
341 {
342 	struct nilfs_transaction_info *cur_ti = current->journal_info;
343 	struct the_nilfs *nilfs = sb->s_fs_info;
344 	struct nilfs_sc_info *sci = nilfs->ns_writer;
345 
346 	WARN_ON(cur_ti);
347 	ti->ti_flags = NILFS_TI_WRITER;
348 	ti->ti_count = 0;
349 	ti->ti_save = cur_ti;
350 	ti->ti_magic = NILFS_TI_MAGIC;
351 	current->journal_info = ti;
352 
353 	for (;;) {
354 		trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
355 			    ti->ti_flags, TRACE_NILFS2_TRANSACTION_TRYLOCK);
356 
357 		down_write(&nilfs->ns_segctor_sem);
358 		if (!test_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags))
359 			break;
360 
361 		nilfs_segctor_do_immediate_flush(sci);
362 
363 		up_write(&nilfs->ns_segctor_sem);
364 		cond_resched();
365 	}
366 	if (gcflag)
367 		ti->ti_flags |= NILFS_TI_GC;
368 
369 	trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
370 			    ti->ti_flags, TRACE_NILFS2_TRANSACTION_LOCK);
371 }
372 
373 static void nilfs_transaction_unlock(struct super_block *sb)
374 {
375 	struct nilfs_transaction_info *ti = current->journal_info;
376 	struct the_nilfs *nilfs = sb->s_fs_info;
377 
378 	BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
379 	BUG_ON(ti->ti_count > 0);
380 
381 	up_write(&nilfs->ns_segctor_sem);
382 	current->journal_info = ti->ti_save;
383 
384 	trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
385 			    ti->ti_flags, TRACE_NILFS2_TRANSACTION_UNLOCK);
386 }
387 
388 static void *nilfs_segctor_map_segsum_entry(struct nilfs_sc_info *sci,
389 					    struct nilfs_segsum_pointer *ssp,
390 					    unsigned int bytes)
391 {
392 	struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
393 	unsigned int blocksize = sci->sc_super->s_blocksize;
394 	void *p;
395 
396 	if (unlikely(ssp->offset + bytes > blocksize)) {
397 		ssp->offset = 0;
398 		BUG_ON(NILFS_SEGBUF_BH_IS_LAST(ssp->bh,
399 					       &segbuf->sb_segsum_buffers));
400 		ssp->bh = NILFS_SEGBUF_NEXT_BH(ssp->bh);
401 	}
402 	p = ssp->bh->b_data + ssp->offset;
403 	ssp->offset += bytes;
404 	return p;
405 }
406 
407 /**
408  * nilfs_segctor_reset_segment_buffer - reset the current segment buffer
409  * @sci: nilfs_sc_info
410  */
411 static int nilfs_segctor_reset_segment_buffer(struct nilfs_sc_info *sci)
412 {
413 	struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
414 	struct buffer_head *sumbh;
415 	unsigned int sumbytes;
416 	unsigned int flags = 0;
417 	int err;
418 
419 	if (nilfs_doing_gc())
420 		flags = NILFS_SS_GC;
421 	err = nilfs_segbuf_reset(segbuf, flags, sci->sc_seg_ctime, sci->sc_cno);
422 	if (unlikely(err))
423 		return err;
424 
425 	sumbh = NILFS_SEGBUF_FIRST_BH(&segbuf->sb_segsum_buffers);
426 	sumbytes = segbuf->sb_sum.sumbytes;
427 	sci->sc_finfo_ptr.bh = sumbh;  sci->sc_finfo_ptr.offset = sumbytes;
428 	sci->sc_binfo_ptr.bh = sumbh;  sci->sc_binfo_ptr.offset = sumbytes;
429 	sci->sc_blk_cnt = sci->sc_datablk_cnt = 0;
430 	return 0;
431 }
432 
433 /**
434  * nilfs_segctor_zeropad_segsum - zero pad the rest of the segment summary area
435  * @sci: segment constructor object
436  *
437  * nilfs_segctor_zeropad_segsum() zero-fills unallocated space at the end of
438  * the current segment summary block.
439  */
440 static void nilfs_segctor_zeropad_segsum(struct nilfs_sc_info *sci)
441 {
442 	struct nilfs_segsum_pointer *ssp;
443 
444 	ssp = sci->sc_blk_cnt > 0 ? &sci->sc_binfo_ptr : &sci->sc_finfo_ptr;
445 	if (ssp->offset < ssp->bh->b_size)
446 		memset(ssp->bh->b_data + ssp->offset, 0,
447 		       ssp->bh->b_size - ssp->offset);
448 }
449 
450 static int nilfs_segctor_feed_segment(struct nilfs_sc_info *sci)
451 {
452 	sci->sc_nblk_this_inc += sci->sc_curseg->sb_sum.nblocks;
453 	if (NILFS_SEGBUF_IS_LAST(sci->sc_curseg, &sci->sc_segbufs))
454 		return -E2BIG; /*
455 				* The current segment is filled up
456 				* (internal code)
457 				*/
458 	nilfs_segctor_zeropad_segsum(sci);
459 	sci->sc_curseg = NILFS_NEXT_SEGBUF(sci->sc_curseg);
460 	return nilfs_segctor_reset_segment_buffer(sci);
461 }
462 
463 static int nilfs_segctor_add_super_root(struct nilfs_sc_info *sci)
464 {
465 	struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
466 	int err;
467 
468 	if (segbuf->sb_sum.nblocks >= segbuf->sb_rest_blocks) {
469 		err = nilfs_segctor_feed_segment(sci);
470 		if (err)
471 			return err;
472 		segbuf = sci->sc_curseg;
473 	}
474 	err = nilfs_segbuf_extend_payload(segbuf, &segbuf->sb_super_root);
475 	if (likely(!err))
476 		segbuf->sb_sum.flags |= NILFS_SS_SR;
477 	return err;
478 }
479 
480 /*
481  * Functions for making segment summary and payloads
482  */
483 static int nilfs_segctor_segsum_block_required(
484 	struct nilfs_sc_info *sci, const struct nilfs_segsum_pointer *ssp,
485 	unsigned int binfo_size)
486 {
487 	unsigned int blocksize = sci->sc_super->s_blocksize;
488 	/* Size of finfo and binfo is enough small against blocksize */
489 
490 	return ssp->offset + binfo_size +
491 		(!sci->sc_blk_cnt ? sizeof(struct nilfs_finfo) : 0) >
492 		blocksize;
493 }
494 
495 static void nilfs_segctor_begin_finfo(struct nilfs_sc_info *sci,
496 				      struct inode *inode)
497 {
498 	sci->sc_curseg->sb_sum.nfinfo++;
499 	sci->sc_binfo_ptr = sci->sc_finfo_ptr;
500 	nilfs_segctor_map_segsum_entry(
501 		sci, &sci->sc_binfo_ptr, sizeof(struct nilfs_finfo));
502 
503 	if (NILFS_I(inode)->i_root &&
504 	    !test_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags))
505 		set_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
506 	/* skip finfo */
507 }
508 
509 static void nilfs_segctor_end_finfo(struct nilfs_sc_info *sci,
510 				    struct inode *inode)
511 {
512 	struct nilfs_finfo *finfo;
513 	struct nilfs_inode_info *ii;
514 	struct nilfs_segment_buffer *segbuf;
515 	__u64 cno;
516 
517 	if (sci->sc_blk_cnt == 0)
518 		return;
519 
520 	ii = NILFS_I(inode);
521 
522 	if (test_bit(NILFS_I_GCINODE, &ii->i_state))
523 		cno = ii->i_cno;
524 	else if (NILFS_ROOT_METADATA_FILE(inode->i_ino))
525 		cno = 0;
526 	else
527 		cno = sci->sc_cno;
528 
529 	finfo = nilfs_segctor_map_segsum_entry(sci, &sci->sc_finfo_ptr,
530 						 sizeof(*finfo));
531 	finfo->fi_ino = cpu_to_le64(inode->i_ino);
532 	finfo->fi_nblocks = cpu_to_le32(sci->sc_blk_cnt);
533 	finfo->fi_ndatablk = cpu_to_le32(sci->sc_datablk_cnt);
534 	finfo->fi_cno = cpu_to_le64(cno);
535 
536 	segbuf = sci->sc_curseg;
537 	segbuf->sb_sum.sumbytes = sci->sc_binfo_ptr.offset +
538 		sci->sc_super->s_blocksize * (segbuf->sb_sum.nsumblk - 1);
539 	sci->sc_finfo_ptr = sci->sc_binfo_ptr;
540 	sci->sc_blk_cnt = sci->sc_datablk_cnt = 0;
541 }
542 
543 static int nilfs_segctor_add_file_block(struct nilfs_sc_info *sci,
544 					struct buffer_head *bh,
545 					struct inode *inode,
546 					unsigned int binfo_size)
547 {
548 	struct nilfs_segment_buffer *segbuf;
549 	int required, err = 0;
550 
551  retry:
552 	segbuf = sci->sc_curseg;
553 	required = nilfs_segctor_segsum_block_required(
554 		sci, &sci->sc_binfo_ptr, binfo_size);
555 	if (segbuf->sb_sum.nblocks + required + 1 > segbuf->sb_rest_blocks) {
556 		nilfs_segctor_end_finfo(sci, inode);
557 		err = nilfs_segctor_feed_segment(sci);
558 		if (err)
559 			return err;
560 		goto retry;
561 	}
562 	if (unlikely(required)) {
563 		nilfs_segctor_zeropad_segsum(sci);
564 		err = nilfs_segbuf_extend_segsum(segbuf);
565 		if (unlikely(err))
566 			goto failed;
567 	}
568 	if (sci->sc_blk_cnt == 0)
569 		nilfs_segctor_begin_finfo(sci, inode);
570 
571 	nilfs_segctor_map_segsum_entry(sci, &sci->sc_binfo_ptr, binfo_size);
572 	/* Substitution to vblocknr is delayed until update_blocknr() */
573 	nilfs_segbuf_add_file_buffer(segbuf, bh);
574 	sci->sc_blk_cnt++;
575  failed:
576 	return err;
577 }
578 
579 /*
580  * Callback functions that enumerate, mark, and collect dirty blocks
581  */
582 static int nilfs_collect_file_data(struct nilfs_sc_info *sci,
583 				   struct buffer_head *bh, struct inode *inode)
584 {
585 	int err;
586 
587 	err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
588 	if (err < 0)
589 		return err;
590 
591 	err = nilfs_segctor_add_file_block(sci, bh, inode,
592 					   sizeof(struct nilfs_binfo_v));
593 	if (!err)
594 		sci->sc_datablk_cnt++;
595 	return err;
596 }
597 
598 static int nilfs_collect_file_node(struct nilfs_sc_info *sci,
599 				   struct buffer_head *bh,
600 				   struct inode *inode)
601 {
602 	return nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
603 }
604 
605 static int nilfs_collect_file_bmap(struct nilfs_sc_info *sci,
606 				   struct buffer_head *bh,
607 				   struct inode *inode)
608 {
609 	WARN_ON(!buffer_dirty(bh));
610 	return nilfs_segctor_add_file_block(sci, bh, inode, sizeof(__le64));
611 }
612 
613 static void nilfs_write_file_data_binfo(struct nilfs_sc_info *sci,
614 					struct nilfs_segsum_pointer *ssp,
615 					union nilfs_binfo *binfo)
616 {
617 	struct nilfs_binfo_v *binfo_v = nilfs_segctor_map_segsum_entry(
618 		sci, ssp, sizeof(*binfo_v));
619 	*binfo_v = binfo->bi_v;
620 }
621 
622 static void nilfs_write_file_node_binfo(struct nilfs_sc_info *sci,
623 					struct nilfs_segsum_pointer *ssp,
624 					union nilfs_binfo *binfo)
625 {
626 	__le64 *vblocknr = nilfs_segctor_map_segsum_entry(
627 		sci, ssp, sizeof(*vblocknr));
628 	*vblocknr = binfo->bi_v.bi_vblocknr;
629 }
630 
631 static const struct nilfs_sc_operations nilfs_sc_file_ops = {
632 	.collect_data = nilfs_collect_file_data,
633 	.collect_node = nilfs_collect_file_node,
634 	.collect_bmap = nilfs_collect_file_bmap,
635 	.write_data_binfo = nilfs_write_file_data_binfo,
636 	.write_node_binfo = nilfs_write_file_node_binfo,
637 };
638 
639 static int nilfs_collect_dat_data(struct nilfs_sc_info *sci,
640 				  struct buffer_head *bh, struct inode *inode)
641 {
642 	int err;
643 
644 	err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
645 	if (err < 0)
646 		return err;
647 
648 	err = nilfs_segctor_add_file_block(sci, bh, inode, sizeof(__le64));
649 	if (!err)
650 		sci->sc_datablk_cnt++;
651 	return err;
652 }
653 
654 static int nilfs_collect_dat_bmap(struct nilfs_sc_info *sci,
655 				  struct buffer_head *bh, struct inode *inode)
656 {
657 	WARN_ON(!buffer_dirty(bh));
658 	return nilfs_segctor_add_file_block(sci, bh, inode,
659 					    sizeof(struct nilfs_binfo_dat));
660 }
661 
662 static void nilfs_write_dat_data_binfo(struct nilfs_sc_info *sci,
663 				       struct nilfs_segsum_pointer *ssp,
664 				       union nilfs_binfo *binfo)
665 {
666 	__le64 *blkoff = nilfs_segctor_map_segsum_entry(sci, ssp,
667 							  sizeof(*blkoff));
668 	*blkoff = binfo->bi_dat.bi_blkoff;
669 }
670 
671 static void nilfs_write_dat_node_binfo(struct nilfs_sc_info *sci,
672 				       struct nilfs_segsum_pointer *ssp,
673 				       union nilfs_binfo *binfo)
674 {
675 	struct nilfs_binfo_dat *binfo_dat =
676 		nilfs_segctor_map_segsum_entry(sci, ssp, sizeof(*binfo_dat));
677 	*binfo_dat = binfo->bi_dat;
678 }
679 
680 static const struct nilfs_sc_operations nilfs_sc_dat_ops = {
681 	.collect_data = nilfs_collect_dat_data,
682 	.collect_node = nilfs_collect_file_node,
683 	.collect_bmap = nilfs_collect_dat_bmap,
684 	.write_data_binfo = nilfs_write_dat_data_binfo,
685 	.write_node_binfo = nilfs_write_dat_node_binfo,
686 };
687 
688 static const struct nilfs_sc_operations nilfs_sc_dsync_ops = {
689 	.collect_data = nilfs_collect_file_data,
690 	.collect_node = NULL,
691 	.collect_bmap = NULL,
692 	.write_data_binfo = nilfs_write_file_data_binfo,
693 	.write_node_binfo = NULL,
694 };
695 
696 static size_t nilfs_lookup_dirty_data_buffers(struct inode *inode,
697 					      struct list_head *listp,
698 					      size_t nlimit,
699 					      loff_t start, loff_t end)
700 {
701 	struct address_space *mapping = inode->i_mapping;
702 	struct folio_batch fbatch;
703 	pgoff_t index = 0, last = ULONG_MAX;
704 	size_t ndirties = 0;
705 	int i;
706 
707 	if (unlikely(start != 0 || end != LLONG_MAX)) {
708 		/*
709 		 * A valid range is given for sync-ing data pages. The
710 		 * range is rounded to per-page; extra dirty buffers
711 		 * may be included if blocksize < pagesize.
712 		 */
713 		index = start >> PAGE_SHIFT;
714 		last = end >> PAGE_SHIFT;
715 	}
716 	folio_batch_init(&fbatch);
717  repeat:
718 	if (unlikely(index > last) ||
719 	      !filemap_get_folios_tag(mapping, &index, last,
720 		      PAGECACHE_TAG_DIRTY, &fbatch))
721 		return ndirties;
722 
723 	for (i = 0; i < folio_batch_count(&fbatch); i++) {
724 		struct buffer_head *bh, *head;
725 		struct folio *folio = fbatch.folios[i];
726 
727 		folio_lock(folio);
728 		if (unlikely(folio->mapping != mapping)) {
729 			/* Exclude folios removed from the address space */
730 			folio_unlock(folio);
731 			continue;
732 		}
733 		head = folio_buffers(folio);
734 		if (!head)
735 			head = create_empty_buffers(folio,
736 					i_blocksize(inode), 0);
737 		folio_unlock(folio);
738 
739 		bh = head;
740 		do {
741 			if (!buffer_dirty(bh) || buffer_async_write(bh))
742 				continue;
743 			get_bh(bh);
744 			list_add_tail(&bh->b_assoc_buffers, listp);
745 			ndirties++;
746 			if (unlikely(ndirties >= nlimit)) {
747 				folio_batch_release(&fbatch);
748 				cond_resched();
749 				return ndirties;
750 			}
751 		} while (bh = bh->b_this_page, bh != head);
752 	}
753 	folio_batch_release(&fbatch);
754 	cond_resched();
755 	goto repeat;
756 }
757 
758 static void nilfs_lookup_dirty_node_buffers(struct inode *inode,
759 					    struct list_head *listp)
760 {
761 	struct nilfs_inode_info *ii = NILFS_I(inode);
762 	struct inode *btnc_inode = ii->i_assoc_inode;
763 	struct folio_batch fbatch;
764 	struct buffer_head *bh, *head;
765 	unsigned int i;
766 	pgoff_t index = 0;
767 
768 	if (!btnc_inode)
769 		return;
770 	folio_batch_init(&fbatch);
771 
772 	while (filemap_get_folios_tag(btnc_inode->i_mapping, &index,
773 				(pgoff_t)-1, PAGECACHE_TAG_DIRTY, &fbatch)) {
774 		for (i = 0; i < folio_batch_count(&fbatch); i++) {
775 			bh = head = folio_buffers(fbatch.folios[i]);
776 			do {
777 				if (buffer_dirty(bh) &&
778 						!buffer_async_write(bh)) {
779 					get_bh(bh);
780 					list_add_tail(&bh->b_assoc_buffers,
781 						      listp);
782 				}
783 				bh = bh->b_this_page;
784 			} while (bh != head);
785 		}
786 		folio_batch_release(&fbatch);
787 		cond_resched();
788 	}
789 }
790 
791 static void nilfs_dispose_list(struct the_nilfs *nilfs,
792 			       struct list_head *head, int force)
793 {
794 	struct nilfs_inode_info *ii, *n;
795 	struct nilfs_inode_info *ivec[SC_N_INODEVEC], **pii;
796 	unsigned int nv = 0;
797 
798 	while (!list_empty(head)) {
799 		spin_lock(&nilfs->ns_inode_lock);
800 		list_for_each_entry_safe(ii, n, head, i_dirty) {
801 			list_del_init(&ii->i_dirty);
802 			if (force) {
803 				if (unlikely(ii->i_bh)) {
804 					brelse(ii->i_bh);
805 					ii->i_bh = NULL;
806 				}
807 			} else if (test_bit(NILFS_I_DIRTY, &ii->i_state)) {
808 				set_bit(NILFS_I_QUEUED, &ii->i_state);
809 				list_add_tail(&ii->i_dirty,
810 					      &nilfs->ns_dirty_files);
811 				continue;
812 			}
813 			ivec[nv++] = ii;
814 			if (nv == SC_N_INODEVEC)
815 				break;
816 		}
817 		spin_unlock(&nilfs->ns_inode_lock);
818 
819 		for (pii = ivec; nv > 0; pii++, nv--)
820 			iput(&(*pii)->vfs_inode);
821 	}
822 }
823 
824 static void nilfs_iput_work_func(struct work_struct *work)
825 {
826 	struct nilfs_sc_info *sci = container_of(work, struct nilfs_sc_info,
827 						 sc_iput_work);
828 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
829 
830 	nilfs_dispose_list(nilfs, &sci->sc_iput_queue, 0);
831 }
832 
833 static int nilfs_test_metadata_dirty(struct the_nilfs *nilfs,
834 				     struct nilfs_root *root)
835 {
836 	int ret = 0;
837 
838 	if (nilfs_mdt_fetch_dirty(root->ifile))
839 		ret++;
840 	if (nilfs_mdt_fetch_dirty(nilfs->ns_cpfile))
841 		ret++;
842 	if (nilfs_mdt_fetch_dirty(nilfs->ns_sufile))
843 		ret++;
844 	if ((ret || nilfs_doing_gc()) && nilfs_mdt_fetch_dirty(nilfs->ns_dat))
845 		ret++;
846 	return ret;
847 }
848 
849 static int nilfs_segctor_clean(struct nilfs_sc_info *sci)
850 {
851 	return list_empty(&sci->sc_dirty_files) &&
852 		!test_bit(NILFS_SC_DIRTY, &sci->sc_flags) &&
853 		sci->sc_nfreesegs == 0 &&
854 		(!nilfs_doing_gc() || list_empty(&sci->sc_gc_inodes));
855 }
856 
857 static int nilfs_segctor_confirm(struct nilfs_sc_info *sci)
858 {
859 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
860 	int ret = 0;
861 
862 	if (nilfs_test_metadata_dirty(nilfs, sci->sc_root))
863 		set_bit(NILFS_SC_DIRTY, &sci->sc_flags);
864 
865 	spin_lock(&nilfs->ns_inode_lock);
866 	if (list_empty(&nilfs->ns_dirty_files) && nilfs_segctor_clean(sci))
867 		ret++;
868 
869 	spin_unlock(&nilfs->ns_inode_lock);
870 	return ret;
871 }
872 
873 static void nilfs_segctor_clear_metadata_dirty(struct nilfs_sc_info *sci)
874 {
875 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
876 
877 	nilfs_mdt_clear_dirty(sci->sc_root->ifile);
878 	nilfs_mdt_clear_dirty(nilfs->ns_cpfile);
879 	nilfs_mdt_clear_dirty(nilfs->ns_sufile);
880 	nilfs_mdt_clear_dirty(nilfs->ns_dat);
881 }
882 
883 static int nilfs_segctor_create_checkpoint(struct nilfs_sc_info *sci)
884 {
885 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
886 	struct buffer_head *bh_cp;
887 	struct nilfs_checkpoint *raw_cp;
888 	int err;
889 
890 	/* XXX: this interface will be changed */
891 	err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, 1,
892 					  &raw_cp, &bh_cp);
893 	if (likely(!err)) {
894 		/*
895 		 * The following code is duplicated with cpfile.  But, it is
896 		 * needed to collect the checkpoint even if it was not newly
897 		 * created.
898 		 */
899 		mark_buffer_dirty(bh_cp);
900 		nilfs_mdt_mark_dirty(nilfs->ns_cpfile);
901 		nilfs_cpfile_put_checkpoint(
902 			nilfs->ns_cpfile, nilfs->ns_cno, bh_cp);
903 	} else if (err == -EINVAL || err == -ENOENT) {
904 		nilfs_error(sci->sc_super,
905 			    "checkpoint creation failed due to metadata corruption.");
906 		err = -EIO;
907 	}
908 	return err;
909 }
910 
911 static int nilfs_segctor_fill_in_checkpoint(struct nilfs_sc_info *sci)
912 {
913 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
914 	struct buffer_head *bh_cp;
915 	struct nilfs_checkpoint *raw_cp;
916 	int err;
917 
918 	err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, 0,
919 					  &raw_cp, &bh_cp);
920 	if (unlikely(err)) {
921 		if (err == -EINVAL || err == -ENOENT) {
922 			nilfs_error(sci->sc_super,
923 				    "checkpoint finalization failed due to metadata corruption.");
924 			err = -EIO;
925 		}
926 		goto failed_ibh;
927 	}
928 	raw_cp->cp_snapshot_list.ssl_next = 0;
929 	raw_cp->cp_snapshot_list.ssl_prev = 0;
930 	raw_cp->cp_inodes_count =
931 		cpu_to_le64(atomic64_read(&sci->sc_root->inodes_count));
932 	raw_cp->cp_blocks_count =
933 		cpu_to_le64(atomic64_read(&sci->sc_root->blocks_count));
934 	raw_cp->cp_nblk_inc =
935 		cpu_to_le64(sci->sc_nblk_inc + sci->sc_nblk_this_inc);
936 	raw_cp->cp_create = cpu_to_le64(sci->sc_seg_ctime);
937 	raw_cp->cp_cno = cpu_to_le64(nilfs->ns_cno);
938 
939 	if (test_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags))
940 		nilfs_checkpoint_clear_minor(raw_cp);
941 	else
942 		nilfs_checkpoint_set_minor(raw_cp);
943 
944 	nilfs_write_inode_common(sci->sc_root->ifile,
945 				 &raw_cp->cp_ifile_inode, 1);
946 	nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, bh_cp);
947 	return 0;
948 
949  failed_ibh:
950 	return err;
951 }
952 
953 static void nilfs_fill_in_file_bmap(struct inode *ifile,
954 				    struct nilfs_inode_info *ii)
955 
956 {
957 	struct buffer_head *ibh;
958 	struct nilfs_inode *raw_inode;
959 
960 	if (test_bit(NILFS_I_BMAP, &ii->i_state)) {
961 		ibh = ii->i_bh;
962 		BUG_ON(!ibh);
963 		raw_inode = nilfs_ifile_map_inode(ifile, ii->vfs_inode.i_ino,
964 						  ibh);
965 		nilfs_bmap_write(ii->i_bmap, raw_inode);
966 		nilfs_ifile_unmap_inode(ifile, ii->vfs_inode.i_ino, ibh);
967 	}
968 }
969 
970 static void nilfs_segctor_fill_in_file_bmap(struct nilfs_sc_info *sci)
971 {
972 	struct nilfs_inode_info *ii;
973 
974 	list_for_each_entry(ii, &sci->sc_dirty_files, i_dirty) {
975 		nilfs_fill_in_file_bmap(sci->sc_root->ifile, ii);
976 		set_bit(NILFS_I_COLLECTED, &ii->i_state);
977 	}
978 }
979 
980 static void nilfs_segctor_fill_in_super_root(struct nilfs_sc_info *sci,
981 					     struct the_nilfs *nilfs)
982 {
983 	struct buffer_head *bh_sr;
984 	struct nilfs_super_root *raw_sr;
985 	unsigned int isz, srsz;
986 
987 	bh_sr = NILFS_LAST_SEGBUF(&sci->sc_segbufs)->sb_super_root;
988 
989 	lock_buffer(bh_sr);
990 	raw_sr = (struct nilfs_super_root *)bh_sr->b_data;
991 	isz = nilfs->ns_inode_size;
992 	srsz = NILFS_SR_BYTES(isz);
993 
994 	raw_sr->sr_sum = 0;  /* Ensure initialization within this update */
995 	raw_sr->sr_bytes = cpu_to_le16(srsz);
996 	raw_sr->sr_nongc_ctime
997 		= cpu_to_le64(nilfs_doing_gc() ?
998 			      nilfs->ns_nongc_ctime : sci->sc_seg_ctime);
999 	raw_sr->sr_flags = 0;
1000 
1001 	nilfs_write_inode_common(nilfs->ns_dat, (void *)raw_sr +
1002 				 NILFS_SR_DAT_OFFSET(isz), 1);
1003 	nilfs_write_inode_common(nilfs->ns_cpfile, (void *)raw_sr +
1004 				 NILFS_SR_CPFILE_OFFSET(isz), 1);
1005 	nilfs_write_inode_common(nilfs->ns_sufile, (void *)raw_sr +
1006 				 NILFS_SR_SUFILE_OFFSET(isz), 1);
1007 	memset((void *)raw_sr + srsz, 0, nilfs->ns_blocksize - srsz);
1008 	set_buffer_uptodate(bh_sr);
1009 	unlock_buffer(bh_sr);
1010 }
1011 
1012 static void nilfs_redirty_inodes(struct list_head *head)
1013 {
1014 	struct nilfs_inode_info *ii;
1015 
1016 	list_for_each_entry(ii, head, i_dirty) {
1017 		if (test_bit(NILFS_I_COLLECTED, &ii->i_state))
1018 			clear_bit(NILFS_I_COLLECTED, &ii->i_state);
1019 	}
1020 }
1021 
1022 static void nilfs_drop_collected_inodes(struct list_head *head)
1023 {
1024 	struct nilfs_inode_info *ii;
1025 
1026 	list_for_each_entry(ii, head, i_dirty) {
1027 		if (!test_and_clear_bit(NILFS_I_COLLECTED, &ii->i_state))
1028 			continue;
1029 
1030 		clear_bit(NILFS_I_INODE_SYNC, &ii->i_state);
1031 		set_bit(NILFS_I_UPDATED, &ii->i_state);
1032 	}
1033 }
1034 
1035 static int nilfs_segctor_apply_buffers(struct nilfs_sc_info *sci,
1036 				       struct inode *inode,
1037 				       struct list_head *listp,
1038 				       int (*collect)(struct nilfs_sc_info *,
1039 						      struct buffer_head *,
1040 						      struct inode *))
1041 {
1042 	struct buffer_head *bh, *n;
1043 	int err = 0;
1044 
1045 	if (collect) {
1046 		list_for_each_entry_safe(bh, n, listp, b_assoc_buffers) {
1047 			list_del_init(&bh->b_assoc_buffers);
1048 			err = collect(sci, bh, inode);
1049 			brelse(bh);
1050 			if (unlikely(err))
1051 				goto dispose_buffers;
1052 		}
1053 		return 0;
1054 	}
1055 
1056  dispose_buffers:
1057 	while (!list_empty(listp)) {
1058 		bh = list_first_entry(listp, struct buffer_head,
1059 				      b_assoc_buffers);
1060 		list_del_init(&bh->b_assoc_buffers);
1061 		brelse(bh);
1062 	}
1063 	return err;
1064 }
1065 
1066 static size_t nilfs_segctor_buffer_rest(struct nilfs_sc_info *sci)
1067 {
1068 	/* Remaining number of blocks within segment buffer */
1069 	return sci->sc_segbuf_nblocks -
1070 		(sci->sc_nblk_this_inc + sci->sc_curseg->sb_sum.nblocks);
1071 }
1072 
1073 static int nilfs_segctor_scan_file(struct nilfs_sc_info *sci,
1074 				   struct inode *inode,
1075 				   const struct nilfs_sc_operations *sc_ops)
1076 {
1077 	LIST_HEAD(data_buffers);
1078 	LIST_HEAD(node_buffers);
1079 	int err;
1080 
1081 	if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
1082 		size_t n, rest = nilfs_segctor_buffer_rest(sci);
1083 
1084 		n = nilfs_lookup_dirty_data_buffers(
1085 			inode, &data_buffers, rest + 1, 0, LLONG_MAX);
1086 		if (n > rest) {
1087 			err = nilfs_segctor_apply_buffers(
1088 				sci, inode, &data_buffers,
1089 				sc_ops->collect_data);
1090 			BUG_ON(!err); /* always receive -E2BIG or true error */
1091 			goto break_or_fail;
1092 		}
1093 	}
1094 	nilfs_lookup_dirty_node_buffers(inode, &node_buffers);
1095 
1096 	if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
1097 		err = nilfs_segctor_apply_buffers(
1098 			sci, inode, &data_buffers, sc_ops->collect_data);
1099 		if (unlikely(err)) {
1100 			/* dispose node list */
1101 			nilfs_segctor_apply_buffers(
1102 				sci, inode, &node_buffers, NULL);
1103 			goto break_or_fail;
1104 		}
1105 		sci->sc_stage.flags |= NILFS_CF_NODE;
1106 	}
1107 	/* Collect node */
1108 	err = nilfs_segctor_apply_buffers(
1109 		sci, inode, &node_buffers, sc_ops->collect_node);
1110 	if (unlikely(err))
1111 		goto break_or_fail;
1112 
1113 	nilfs_bmap_lookup_dirty_buffers(NILFS_I(inode)->i_bmap, &node_buffers);
1114 	err = nilfs_segctor_apply_buffers(
1115 		sci, inode, &node_buffers, sc_ops->collect_bmap);
1116 	if (unlikely(err))
1117 		goto break_or_fail;
1118 
1119 	nilfs_segctor_end_finfo(sci, inode);
1120 	sci->sc_stage.flags &= ~NILFS_CF_NODE;
1121 
1122  break_or_fail:
1123 	return err;
1124 }
1125 
1126 static int nilfs_segctor_scan_file_dsync(struct nilfs_sc_info *sci,
1127 					 struct inode *inode)
1128 {
1129 	LIST_HEAD(data_buffers);
1130 	size_t n, rest = nilfs_segctor_buffer_rest(sci);
1131 	int err;
1132 
1133 	n = nilfs_lookup_dirty_data_buffers(inode, &data_buffers, rest + 1,
1134 					    sci->sc_dsync_start,
1135 					    sci->sc_dsync_end);
1136 
1137 	err = nilfs_segctor_apply_buffers(sci, inode, &data_buffers,
1138 					  nilfs_collect_file_data);
1139 	if (!err) {
1140 		nilfs_segctor_end_finfo(sci, inode);
1141 		BUG_ON(n > rest);
1142 		/* always receive -E2BIG or true error if n > rest */
1143 	}
1144 	return err;
1145 }
1146 
1147 static int nilfs_segctor_collect_blocks(struct nilfs_sc_info *sci, int mode)
1148 {
1149 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
1150 	struct list_head *head;
1151 	struct nilfs_inode_info *ii;
1152 	size_t ndone;
1153 	int err = 0;
1154 
1155 	switch (nilfs_sc_cstage_get(sci)) {
1156 	case NILFS_ST_INIT:
1157 		/* Pre-processes */
1158 		sci->sc_stage.flags = 0;
1159 
1160 		if (!test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags)) {
1161 			sci->sc_nblk_inc = 0;
1162 			sci->sc_curseg->sb_sum.flags = NILFS_SS_LOGBGN;
1163 			if (mode == SC_LSEG_DSYNC) {
1164 				nilfs_sc_cstage_set(sci, NILFS_ST_DSYNC);
1165 				goto dsync_mode;
1166 			}
1167 		}
1168 
1169 		sci->sc_stage.dirty_file_ptr = NULL;
1170 		sci->sc_stage.gc_inode_ptr = NULL;
1171 		if (mode == SC_FLUSH_DAT) {
1172 			nilfs_sc_cstage_set(sci, NILFS_ST_DAT);
1173 			goto dat_stage;
1174 		}
1175 		nilfs_sc_cstage_inc(sci);
1176 		fallthrough;
1177 	case NILFS_ST_GC:
1178 		if (nilfs_doing_gc()) {
1179 			head = &sci->sc_gc_inodes;
1180 			ii = list_prepare_entry(sci->sc_stage.gc_inode_ptr,
1181 						head, i_dirty);
1182 			list_for_each_entry_continue(ii, head, i_dirty) {
1183 				err = nilfs_segctor_scan_file(
1184 					sci, &ii->vfs_inode,
1185 					&nilfs_sc_file_ops);
1186 				if (unlikely(err)) {
1187 					sci->sc_stage.gc_inode_ptr = list_entry(
1188 						ii->i_dirty.prev,
1189 						struct nilfs_inode_info,
1190 						i_dirty);
1191 					goto break_or_fail;
1192 				}
1193 				set_bit(NILFS_I_COLLECTED, &ii->i_state);
1194 			}
1195 			sci->sc_stage.gc_inode_ptr = NULL;
1196 		}
1197 		nilfs_sc_cstage_inc(sci);
1198 		fallthrough;
1199 	case NILFS_ST_FILE:
1200 		head = &sci->sc_dirty_files;
1201 		ii = list_prepare_entry(sci->sc_stage.dirty_file_ptr, head,
1202 					i_dirty);
1203 		list_for_each_entry_continue(ii, head, i_dirty) {
1204 			clear_bit(NILFS_I_DIRTY, &ii->i_state);
1205 
1206 			err = nilfs_segctor_scan_file(sci, &ii->vfs_inode,
1207 						      &nilfs_sc_file_ops);
1208 			if (unlikely(err)) {
1209 				sci->sc_stage.dirty_file_ptr =
1210 					list_entry(ii->i_dirty.prev,
1211 						   struct nilfs_inode_info,
1212 						   i_dirty);
1213 				goto break_or_fail;
1214 			}
1215 			/* sci->sc_stage.dirty_file_ptr = NILFS_I(inode); */
1216 			/* XXX: required ? */
1217 		}
1218 		sci->sc_stage.dirty_file_ptr = NULL;
1219 		if (mode == SC_FLUSH_FILE) {
1220 			nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1221 			return 0;
1222 		}
1223 		nilfs_sc_cstage_inc(sci);
1224 		sci->sc_stage.flags |= NILFS_CF_IFILE_STARTED;
1225 		fallthrough;
1226 	case NILFS_ST_IFILE:
1227 		err = nilfs_segctor_scan_file(sci, sci->sc_root->ifile,
1228 					      &nilfs_sc_file_ops);
1229 		if (unlikely(err))
1230 			break;
1231 		nilfs_sc_cstage_inc(sci);
1232 		/* Creating a checkpoint */
1233 		err = nilfs_segctor_create_checkpoint(sci);
1234 		if (unlikely(err))
1235 			break;
1236 		fallthrough;
1237 	case NILFS_ST_CPFILE:
1238 		err = nilfs_segctor_scan_file(sci, nilfs->ns_cpfile,
1239 					      &nilfs_sc_file_ops);
1240 		if (unlikely(err))
1241 			break;
1242 		nilfs_sc_cstage_inc(sci);
1243 		fallthrough;
1244 	case NILFS_ST_SUFILE:
1245 		err = nilfs_sufile_freev(nilfs->ns_sufile, sci->sc_freesegs,
1246 					 sci->sc_nfreesegs, &ndone);
1247 		if (unlikely(err)) {
1248 			nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1249 						  sci->sc_freesegs, ndone,
1250 						  NULL);
1251 			break;
1252 		}
1253 		sci->sc_stage.flags |= NILFS_CF_SUFREED;
1254 
1255 		err = nilfs_segctor_scan_file(sci, nilfs->ns_sufile,
1256 					      &nilfs_sc_file_ops);
1257 		if (unlikely(err))
1258 			break;
1259 		nilfs_sc_cstage_inc(sci);
1260 		fallthrough;
1261 	case NILFS_ST_DAT:
1262  dat_stage:
1263 		err = nilfs_segctor_scan_file(sci, nilfs->ns_dat,
1264 					      &nilfs_sc_dat_ops);
1265 		if (unlikely(err))
1266 			break;
1267 		if (mode == SC_FLUSH_DAT) {
1268 			nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1269 			return 0;
1270 		}
1271 		nilfs_sc_cstage_inc(sci);
1272 		fallthrough;
1273 	case NILFS_ST_SR:
1274 		if (mode == SC_LSEG_SR) {
1275 			/* Appending a super root */
1276 			err = nilfs_segctor_add_super_root(sci);
1277 			if (unlikely(err))
1278 				break;
1279 		}
1280 		/* End of a logical segment */
1281 		sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
1282 		nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1283 		return 0;
1284 	case NILFS_ST_DSYNC:
1285  dsync_mode:
1286 		sci->sc_curseg->sb_sum.flags |= NILFS_SS_SYNDT;
1287 		ii = sci->sc_dsync_inode;
1288 		if (!test_bit(NILFS_I_BUSY, &ii->i_state))
1289 			break;
1290 
1291 		err = nilfs_segctor_scan_file_dsync(sci, &ii->vfs_inode);
1292 		if (unlikely(err))
1293 			break;
1294 		sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
1295 		nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1296 		return 0;
1297 	case NILFS_ST_DONE:
1298 		return 0;
1299 	default:
1300 		BUG();
1301 	}
1302 
1303  break_or_fail:
1304 	return err;
1305 }
1306 
1307 /**
1308  * nilfs_segctor_begin_construction - setup segment buffer to make a new log
1309  * @sci: nilfs_sc_info
1310  * @nilfs: nilfs object
1311  */
1312 static int nilfs_segctor_begin_construction(struct nilfs_sc_info *sci,
1313 					    struct the_nilfs *nilfs)
1314 {
1315 	struct nilfs_segment_buffer *segbuf, *prev;
1316 	__u64 nextnum;
1317 	int err, alloc = 0;
1318 
1319 	segbuf = nilfs_segbuf_new(sci->sc_super);
1320 	if (unlikely(!segbuf))
1321 		return -ENOMEM;
1322 
1323 	if (list_empty(&sci->sc_write_logs)) {
1324 		nilfs_segbuf_map(segbuf, nilfs->ns_segnum,
1325 				 nilfs->ns_pseg_offset, nilfs);
1326 		if (segbuf->sb_rest_blocks < NILFS_PSEG_MIN_BLOCKS) {
1327 			nilfs_shift_to_next_segment(nilfs);
1328 			nilfs_segbuf_map(segbuf, nilfs->ns_segnum, 0, nilfs);
1329 		}
1330 
1331 		segbuf->sb_sum.seg_seq = nilfs->ns_seg_seq;
1332 		nextnum = nilfs->ns_nextnum;
1333 
1334 		if (nilfs->ns_segnum == nilfs->ns_nextnum)
1335 			/* Start from the head of a new full segment */
1336 			alloc++;
1337 	} else {
1338 		/* Continue logs */
1339 		prev = NILFS_LAST_SEGBUF(&sci->sc_write_logs);
1340 		nilfs_segbuf_map_cont(segbuf, prev);
1341 		segbuf->sb_sum.seg_seq = prev->sb_sum.seg_seq;
1342 		nextnum = prev->sb_nextnum;
1343 
1344 		if (segbuf->sb_rest_blocks < NILFS_PSEG_MIN_BLOCKS) {
1345 			nilfs_segbuf_map(segbuf, prev->sb_nextnum, 0, nilfs);
1346 			segbuf->sb_sum.seg_seq++;
1347 			alloc++;
1348 		}
1349 	}
1350 
1351 	err = nilfs_sufile_mark_dirty(nilfs->ns_sufile, segbuf->sb_segnum);
1352 	if (err)
1353 		goto failed;
1354 
1355 	if (alloc) {
1356 		err = nilfs_sufile_alloc(nilfs->ns_sufile, &nextnum);
1357 		if (err)
1358 			goto failed;
1359 	}
1360 	nilfs_segbuf_set_next_segnum(segbuf, nextnum, nilfs);
1361 
1362 	BUG_ON(!list_empty(&sci->sc_segbufs));
1363 	list_add_tail(&segbuf->sb_list, &sci->sc_segbufs);
1364 	sci->sc_segbuf_nblocks = segbuf->sb_rest_blocks;
1365 	return 0;
1366 
1367  failed:
1368 	nilfs_segbuf_free(segbuf);
1369 	return err;
1370 }
1371 
1372 static int nilfs_segctor_extend_segments(struct nilfs_sc_info *sci,
1373 					 struct the_nilfs *nilfs, int nadd)
1374 {
1375 	struct nilfs_segment_buffer *segbuf, *prev;
1376 	struct inode *sufile = nilfs->ns_sufile;
1377 	__u64 nextnextnum;
1378 	LIST_HEAD(list);
1379 	int err, ret, i;
1380 
1381 	prev = NILFS_LAST_SEGBUF(&sci->sc_segbufs);
1382 	/*
1383 	 * Since the segment specified with nextnum might be allocated during
1384 	 * the previous construction, the buffer including its segusage may
1385 	 * not be dirty.  The following call ensures that the buffer is dirty
1386 	 * and will pin the buffer on memory until the sufile is written.
1387 	 */
1388 	err = nilfs_sufile_mark_dirty(sufile, prev->sb_nextnum);
1389 	if (unlikely(err))
1390 		return err;
1391 
1392 	for (i = 0; i < nadd; i++) {
1393 		/* extend segment info */
1394 		err = -ENOMEM;
1395 		segbuf = nilfs_segbuf_new(sci->sc_super);
1396 		if (unlikely(!segbuf))
1397 			goto failed;
1398 
1399 		/* map this buffer to region of segment on-disk */
1400 		nilfs_segbuf_map(segbuf, prev->sb_nextnum, 0, nilfs);
1401 		sci->sc_segbuf_nblocks += segbuf->sb_rest_blocks;
1402 
1403 		/* allocate the next next full segment */
1404 		err = nilfs_sufile_alloc(sufile, &nextnextnum);
1405 		if (unlikely(err))
1406 			goto failed_segbuf;
1407 
1408 		segbuf->sb_sum.seg_seq = prev->sb_sum.seg_seq + 1;
1409 		nilfs_segbuf_set_next_segnum(segbuf, nextnextnum, nilfs);
1410 
1411 		list_add_tail(&segbuf->sb_list, &list);
1412 		prev = segbuf;
1413 	}
1414 	list_splice_tail(&list, &sci->sc_segbufs);
1415 	return 0;
1416 
1417  failed_segbuf:
1418 	nilfs_segbuf_free(segbuf);
1419  failed:
1420 	list_for_each_entry(segbuf, &list, sb_list) {
1421 		ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1422 		WARN_ON(ret); /* never fails */
1423 	}
1424 	nilfs_destroy_logs(&list);
1425 	return err;
1426 }
1427 
1428 static void nilfs_free_incomplete_logs(struct list_head *logs,
1429 				       struct the_nilfs *nilfs)
1430 {
1431 	struct nilfs_segment_buffer *segbuf, *prev;
1432 	struct inode *sufile = nilfs->ns_sufile;
1433 	int ret;
1434 
1435 	segbuf = NILFS_FIRST_SEGBUF(logs);
1436 	if (nilfs->ns_nextnum != segbuf->sb_nextnum) {
1437 		ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1438 		WARN_ON(ret); /* never fails */
1439 	}
1440 	if (atomic_read(&segbuf->sb_err)) {
1441 		/* Case 1: The first segment failed */
1442 		if (segbuf->sb_pseg_start != segbuf->sb_fseg_start)
1443 			/*
1444 			 * Case 1a:  Partial segment appended into an existing
1445 			 * segment
1446 			 */
1447 			nilfs_terminate_segment(nilfs, segbuf->sb_fseg_start,
1448 						segbuf->sb_fseg_end);
1449 		else /* Case 1b:  New full segment */
1450 			set_nilfs_discontinued(nilfs);
1451 	}
1452 
1453 	prev = segbuf;
1454 	list_for_each_entry_continue(segbuf, logs, sb_list) {
1455 		if (prev->sb_nextnum != segbuf->sb_nextnum) {
1456 			ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1457 			WARN_ON(ret); /* never fails */
1458 		}
1459 		if (atomic_read(&segbuf->sb_err) &&
1460 		    segbuf->sb_segnum != nilfs->ns_nextnum)
1461 			/* Case 2: extended segment (!= next) failed */
1462 			nilfs_sufile_set_error(sufile, segbuf->sb_segnum);
1463 		prev = segbuf;
1464 	}
1465 }
1466 
1467 static void nilfs_segctor_update_segusage(struct nilfs_sc_info *sci,
1468 					  struct inode *sufile)
1469 {
1470 	struct nilfs_segment_buffer *segbuf;
1471 	unsigned long live_blocks;
1472 	int ret;
1473 
1474 	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1475 		live_blocks = segbuf->sb_sum.nblocks +
1476 			(segbuf->sb_pseg_start - segbuf->sb_fseg_start);
1477 		ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1478 						     live_blocks,
1479 						     sci->sc_seg_ctime);
1480 		WARN_ON(ret); /* always succeed because the segusage is dirty */
1481 	}
1482 }
1483 
1484 static void nilfs_cancel_segusage(struct list_head *logs, struct inode *sufile)
1485 {
1486 	struct nilfs_segment_buffer *segbuf;
1487 	int ret;
1488 
1489 	segbuf = NILFS_FIRST_SEGBUF(logs);
1490 	ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1491 					     segbuf->sb_pseg_start -
1492 					     segbuf->sb_fseg_start, 0);
1493 	WARN_ON(ret); /* always succeed because the segusage is dirty */
1494 
1495 	list_for_each_entry_continue(segbuf, logs, sb_list) {
1496 		ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1497 						     0, 0);
1498 		WARN_ON(ret); /* always succeed */
1499 	}
1500 }
1501 
1502 static void nilfs_segctor_truncate_segments(struct nilfs_sc_info *sci,
1503 					    struct nilfs_segment_buffer *last,
1504 					    struct inode *sufile)
1505 {
1506 	struct nilfs_segment_buffer *segbuf = last;
1507 	int ret;
1508 
1509 	list_for_each_entry_continue(segbuf, &sci->sc_segbufs, sb_list) {
1510 		sci->sc_segbuf_nblocks -= segbuf->sb_rest_blocks;
1511 		ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1512 		WARN_ON(ret);
1513 	}
1514 	nilfs_truncate_logs(&sci->sc_segbufs, last);
1515 }
1516 
1517 
1518 static int nilfs_segctor_collect(struct nilfs_sc_info *sci,
1519 				 struct the_nilfs *nilfs, int mode)
1520 {
1521 	struct nilfs_cstage prev_stage = sci->sc_stage;
1522 	int err, nadd = 1;
1523 
1524 	/* Collection retry loop */
1525 	for (;;) {
1526 		sci->sc_nblk_this_inc = 0;
1527 		sci->sc_curseg = NILFS_FIRST_SEGBUF(&sci->sc_segbufs);
1528 
1529 		err = nilfs_segctor_reset_segment_buffer(sci);
1530 		if (unlikely(err))
1531 			goto failed;
1532 
1533 		err = nilfs_segctor_collect_blocks(sci, mode);
1534 		sci->sc_nblk_this_inc += sci->sc_curseg->sb_sum.nblocks;
1535 		if (!err)
1536 			break;
1537 
1538 		if (unlikely(err != -E2BIG))
1539 			goto failed;
1540 
1541 		/* The current segment is filled up */
1542 		if (mode != SC_LSEG_SR ||
1543 		    nilfs_sc_cstage_get(sci) < NILFS_ST_CPFILE)
1544 			break;
1545 
1546 		nilfs_clear_logs(&sci->sc_segbufs);
1547 
1548 		if (sci->sc_stage.flags & NILFS_CF_SUFREED) {
1549 			err = nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1550 							sci->sc_freesegs,
1551 							sci->sc_nfreesegs,
1552 							NULL);
1553 			WARN_ON(err); /* do not happen */
1554 			sci->sc_stage.flags &= ~NILFS_CF_SUFREED;
1555 		}
1556 
1557 		err = nilfs_segctor_extend_segments(sci, nilfs, nadd);
1558 		if (unlikely(err))
1559 			return err;
1560 
1561 		nadd = min_t(int, nadd << 1, SC_MAX_SEGDELTA);
1562 		sci->sc_stage = prev_stage;
1563 	}
1564 	nilfs_segctor_zeropad_segsum(sci);
1565 	nilfs_segctor_truncate_segments(sci, sci->sc_curseg, nilfs->ns_sufile);
1566 	return 0;
1567 
1568  failed:
1569 	return err;
1570 }
1571 
1572 static void nilfs_list_replace_buffer(struct buffer_head *old_bh,
1573 				      struct buffer_head *new_bh)
1574 {
1575 	BUG_ON(!list_empty(&new_bh->b_assoc_buffers));
1576 
1577 	list_replace_init(&old_bh->b_assoc_buffers, &new_bh->b_assoc_buffers);
1578 	/* The caller must release old_bh */
1579 }
1580 
1581 static int
1582 nilfs_segctor_update_payload_blocknr(struct nilfs_sc_info *sci,
1583 				     struct nilfs_segment_buffer *segbuf,
1584 				     int mode)
1585 {
1586 	struct inode *inode = NULL;
1587 	sector_t blocknr;
1588 	unsigned long nfinfo = segbuf->sb_sum.nfinfo;
1589 	unsigned long nblocks = 0, ndatablk = 0;
1590 	const struct nilfs_sc_operations *sc_op = NULL;
1591 	struct nilfs_segsum_pointer ssp;
1592 	struct nilfs_finfo *finfo = NULL;
1593 	union nilfs_binfo binfo;
1594 	struct buffer_head *bh, *bh_org;
1595 	ino_t ino = 0;
1596 	int err = 0;
1597 
1598 	if (!nfinfo)
1599 		goto out;
1600 
1601 	blocknr = segbuf->sb_pseg_start + segbuf->sb_sum.nsumblk;
1602 	ssp.bh = NILFS_SEGBUF_FIRST_BH(&segbuf->sb_segsum_buffers);
1603 	ssp.offset = sizeof(struct nilfs_segment_summary);
1604 
1605 	list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
1606 		if (bh == segbuf->sb_super_root)
1607 			break;
1608 		if (!finfo) {
1609 			finfo =	nilfs_segctor_map_segsum_entry(
1610 				sci, &ssp, sizeof(*finfo));
1611 			ino = le64_to_cpu(finfo->fi_ino);
1612 			nblocks = le32_to_cpu(finfo->fi_nblocks);
1613 			ndatablk = le32_to_cpu(finfo->fi_ndatablk);
1614 
1615 			inode = bh->b_folio->mapping->host;
1616 
1617 			if (mode == SC_LSEG_DSYNC)
1618 				sc_op = &nilfs_sc_dsync_ops;
1619 			else if (ino == NILFS_DAT_INO)
1620 				sc_op = &nilfs_sc_dat_ops;
1621 			else /* file blocks */
1622 				sc_op = &nilfs_sc_file_ops;
1623 		}
1624 		bh_org = bh;
1625 		get_bh(bh_org);
1626 		err = nilfs_bmap_assign(NILFS_I(inode)->i_bmap, &bh, blocknr,
1627 					&binfo);
1628 		if (bh != bh_org)
1629 			nilfs_list_replace_buffer(bh_org, bh);
1630 		brelse(bh_org);
1631 		if (unlikely(err))
1632 			goto failed_bmap;
1633 
1634 		if (ndatablk > 0)
1635 			sc_op->write_data_binfo(sci, &ssp, &binfo);
1636 		else
1637 			sc_op->write_node_binfo(sci, &ssp, &binfo);
1638 
1639 		blocknr++;
1640 		if (--nblocks == 0) {
1641 			finfo = NULL;
1642 			if (--nfinfo == 0)
1643 				break;
1644 		} else if (ndatablk > 0)
1645 			ndatablk--;
1646 	}
1647  out:
1648 	return 0;
1649 
1650  failed_bmap:
1651 	return err;
1652 }
1653 
1654 static int nilfs_segctor_assign(struct nilfs_sc_info *sci, int mode)
1655 {
1656 	struct nilfs_segment_buffer *segbuf;
1657 	int err;
1658 
1659 	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1660 		err = nilfs_segctor_update_payload_blocknr(sci, segbuf, mode);
1661 		if (unlikely(err))
1662 			return err;
1663 		nilfs_segbuf_fill_in_segsum(segbuf);
1664 	}
1665 	return 0;
1666 }
1667 
1668 static void nilfs_begin_page_io(struct page *page)
1669 {
1670 	if (!page || PageWriteback(page))
1671 		/*
1672 		 * For split b-tree node pages, this function may be called
1673 		 * twice.  We ignore the 2nd or later calls by this check.
1674 		 */
1675 		return;
1676 
1677 	lock_page(page);
1678 	clear_page_dirty_for_io(page);
1679 	set_page_writeback(page);
1680 	unlock_page(page);
1681 }
1682 
1683 static void nilfs_segctor_prepare_write(struct nilfs_sc_info *sci)
1684 {
1685 	struct nilfs_segment_buffer *segbuf;
1686 	struct page *bd_page = NULL, *fs_page = NULL;
1687 
1688 	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1689 		struct buffer_head *bh;
1690 
1691 		list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1692 				    b_assoc_buffers) {
1693 			if (bh->b_page != bd_page) {
1694 				if (bd_page) {
1695 					lock_page(bd_page);
1696 					clear_page_dirty_for_io(bd_page);
1697 					set_page_writeback(bd_page);
1698 					unlock_page(bd_page);
1699 				}
1700 				bd_page = bh->b_page;
1701 			}
1702 		}
1703 
1704 		list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1705 				    b_assoc_buffers) {
1706 			set_buffer_async_write(bh);
1707 			if (bh == segbuf->sb_super_root) {
1708 				if (bh->b_page != bd_page) {
1709 					lock_page(bd_page);
1710 					clear_page_dirty_for_io(bd_page);
1711 					set_page_writeback(bd_page);
1712 					unlock_page(bd_page);
1713 					bd_page = bh->b_page;
1714 				}
1715 				break;
1716 			}
1717 			if (bh->b_page != fs_page) {
1718 				nilfs_begin_page_io(fs_page);
1719 				fs_page = bh->b_page;
1720 			}
1721 		}
1722 	}
1723 	if (bd_page) {
1724 		lock_page(bd_page);
1725 		clear_page_dirty_for_io(bd_page);
1726 		set_page_writeback(bd_page);
1727 		unlock_page(bd_page);
1728 	}
1729 	nilfs_begin_page_io(fs_page);
1730 }
1731 
1732 static int nilfs_segctor_write(struct nilfs_sc_info *sci,
1733 			       struct the_nilfs *nilfs)
1734 {
1735 	int ret;
1736 
1737 	ret = nilfs_write_logs(&sci->sc_segbufs, nilfs);
1738 	list_splice_tail_init(&sci->sc_segbufs, &sci->sc_write_logs);
1739 	return ret;
1740 }
1741 
1742 static void nilfs_end_page_io(struct page *page, int err)
1743 {
1744 	if (!page)
1745 		return;
1746 
1747 	if (buffer_nilfs_node(page_buffers(page)) && !PageWriteback(page)) {
1748 		/*
1749 		 * For b-tree node pages, this function may be called twice
1750 		 * or more because they might be split in a segment.
1751 		 */
1752 		if (PageDirty(page)) {
1753 			/*
1754 			 * For pages holding split b-tree node buffers, dirty
1755 			 * flag on the buffers may be cleared discretely.
1756 			 * In that case, the page is once redirtied for
1757 			 * remaining buffers, and it must be cancelled if
1758 			 * all the buffers get cleaned later.
1759 			 */
1760 			lock_page(page);
1761 			if (nilfs_page_buffers_clean(page))
1762 				__nilfs_clear_page_dirty(page);
1763 			unlock_page(page);
1764 		}
1765 		return;
1766 	}
1767 
1768 	if (!err) {
1769 		if (!nilfs_page_buffers_clean(page))
1770 			__set_page_dirty_nobuffers(page);
1771 		ClearPageError(page);
1772 	} else {
1773 		__set_page_dirty_nobuffers(page);
1774 		SetPageError(page);
1775 	}
1776 
1777 	end_page_writeback(page);
1778 }
1779 
1780 static void nilfs_abort_logs(struct list_head *logs, int err)
1781 {
1782 	struct nilfs_segment_buffer *segbuf;
1783 	struct page *bd_page = NULL, *fs_page = NULL;
1784 	struct buffer_head *bh;
1785 
1786 	if (list_empty(logs))
1787 		return;
1788 
1789 	list_for_each_entry(segbuf, logs, sb_list) {
1790 		list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1791 				    b_assoc_buffers) {
1792 			clear_buffer_uptodate(bh);
1793 			if (bh->b_page != bd_page) {
1794 				if (bd_page)
1795 					end_page_writeback(bd_page);
1796 				bd_page = bh->b_page;
1797 			}
1798 		}
1799 
1800 		list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1801 				    b_assoc_buffers) {
1802 			clear_buffer_async_write(bh);
1803 			if (bh == segbuf->sb_super_root) {
1804 				clear_buffer_uptodate(bh);
1805 				if (bh->b_page != bd_page) {
1806 					end_page_writeback(bd_page);
1807 					bd_page = bh->b_page;
1808 				}
1809 				break;
1810 			}
1811 			if (bh->b_page != fs_page) {
1812 				nilfs_end_page_io(fs_page, err);
1813 				fs_page = bh->b_page;
1814 			}
1815 		}
1816 	}
1817 	if (bd_page)
1818 		end_page_writeback(bd_page);
1819 
1820 	nilfs_end_page_io(fs_page, err);
1821 }
1822 
1823 static void nilfs_segctor_abort_construction(struct nilfs_sc_info *sci,
1824 					     struct the_nilfs *nilfs, int err)
1825 {
1826 	LIST_HEAD(logs);
1827 	int ret;
1828 
1829 	list_splice_tail_init(&sci->sc_write_logs, &logs);
1830 	ret = nilfs_wait_on_logs(&logs);
1831 	nilfs_abort_logs(&logs, ret ? : err);
1832 
1833 	list_splice_tail_init(&sci->sc_segbufs, &logs);
1834 	nilfs_cancel_segusage(&logs, nilfs->ns_sufile);
1835 	nilfs_free_incomplete_logs(&logs, nilfs);
1836 
1837 	if (sci->sc_stage.flags & NILFS_CF_SUFREED) {
1838 		ret = nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1839 						sci->sc_freesegs,
1840 						sci->sc_nfreesegs,
1841 						NULL);
1842 		WARN_ON(ret); /* do not happen */
1843 	}
1844 
1845 	nilfs_destroy_logs(&logs);
1846 }
1847 
1848 static void nilfs_set_next_segment(struct the_nilfs *nilfs,
1849 				   struct nilfs_segment_buffer *segbuf)
1850 {
1851 	nilfs->ns_segnum = segbuf->sb_segnum;
1852 	nilfs->ns_nextnum = segbuf->sb_nextnum;
1853 	nilfs->ns_pseg_offset = segbuf->sb_pseg_start - segbuf->sb_fseg_start
1854 		+ segbuf->sb_sum.nblocks;
1855 	nilfs->ns_seg_seq = segbuf->sb_sum.seg_seq;
1856 	nilfs->ns_ctime = segbuf->sb_sum.ctime;
1857 }
1858 
1859 static void nilfs_segctor_complete_write(struct nilfs_sc_info *sci)
1860 {
1861 	struct nilfs_segment_buffer *segbuf;
1862 	struct page *bd_page = NULL, *fs_page = NULL;
1863 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
1864 	int update_sr = false;
1865 
1866 	list_for_each_entry(segbuf, &sci->sc_write_logs, sb_list) {
1867 		struct buffer_head *bh;
1868 
1869 		list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1870 				    b_assoc_buffers) {
1871 			set_buffer_uptodate(bh);
1872 			clear_buffer_dirty(bh);
1873 			if (bh->b_page != bd_page) {
1874 				if (bd_page)
1875 					end_page_writeback(bd_page);
1876 				bd_page = bh->b_page;
1877 			}
1878 		}
1879 		/*
1880 		 * We assume that the buffers which belong to the same page
1881 		 * continue over the buffer list.
1882 		 * Under this assumption, the last BHs of pages is
1883 		 * identifiable by the discontinuity of bh->b_page
1884 		 * (page != fs_page).
1885 		 *
1886 		 * For B-tree node blocks, however, this assumption is not
1887 		 * guaranteed.  The cleanup code of B-tree node pages needs
1888 		 * special care.
1889 		 */
1890 		list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1891 				    b_assoc_buffers) {
1892 			const unsigned long set_bits = BIT(BH_Uptodate);
1893 			const unsigned long clear_bits =
1894 				(BIT(BH_Dirty) | BIT(BH_Async_Write) |
1895 				 BIT(BH_Delay) | BIT(BH_NILFS_Volatile) |
1896 				 BIT(BH_NILFS_Redirected));
1897 
1898 			set_mask_bits(&bh->b_state, clear_bits, set_bits);
1899 			if (bh == segbuf->sb_super_root) {
1900 				if (bh->b_page != bd_page) {
1901 					end_page_writeback(bd_page);
1902 					bd_page = bh->b_page;
1903 				}
1904 				update_sr = true;
1905 				break;
1906 			}
1907 			if (bh->b_page != fs_page) {
1908 				nilfs_end_page_io(fs_page, 0);
1909 				fs_page = bh->b_page;
1910 			}
1911 		}
1912 
1913 		if (!nilfs_segbuf_simplex(segbuf)) {
1914 			if (segbuf->sb_sum.flags & NILFS_SS_LOGBGN) {
1915 				set_bit(NILFS_SC_UNCLOSED, &sci->sc_flags);
1916 				sci->sc_lseg_stime = jiffies;
1917 			}
1918 			if (segbuf->sb_sum.flags & NILFS_SS_LOGEND)
1919 				clear_bit(NILFS_SC_UNCLOSED, &sci->sc_flags);
1920 		}
1921 	}
1922 	/*
1923 	 * Since pages may continue over multiple segment buffers,
1924 	 * end of the last page must be checked outside of the loop.
1925 	 */
1926 	if (bd_page)
1927 		end_page_writeback(bd_page);
1928 
1929 	nilfs_end_page_io(fs_page, 0);
1930 
1931 	nilfs_drop_collected_inodes(&sci->sc_dirty_files);
1932 
1933 	if (nilfs_doing_gc())
1934 		nilfs_drop_collected_inodes(&sci->sc_gc_inodes);
1935 	else
1936 		nilfs->ns_nongc_ctime = sci->sc_seg_ctime;
1937 
1938 	sci->sc_nblk_inc += sci->sc_nblk_this_inc;
1939 
1940 	segbuf = NILFS_LAST_SEGBUF(&sci->sc_write_logs);
1941 	nilfs_set_next_segment(nilfs, segbuf);
1942 
1943 	if (update_sr) {
1944 		nilfs->ns_flushed_device = 0;
1945 		nilfs_set_last_segment(nilfs, segbuf->sb_pseg_start,
1946 				       segbuf->sb_sum.seg_seq, nilfs->ns_cno++);
1947 
1948 		clear_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
1949 		clear_bit(NILFS_SC_DIRTY, &sci->sc_flags);
1950 		set_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags);
1951 		nilfs_segctor_clear_metadata_dirty(sci);
1952 	} else
1953 		clear_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags);
1954 }
1955 
1956 static int nilfs_segctor_wait(struct nilfs_sc_info *sci)
1957 {
1958 	int ret;
1959 
1960 	ret = nilfs_wait_on_logs(&sci->sc_write_logs);
1961 	if (!ret) {
1962 		nilfs_segctor_complete_write(sci);
1963 		nilfs_destroy_logs(&sci->sc_write_logs);
1964 	}
1965 	return ret;
1966 }
1967 
1968 static int nilfs_segctor_collect_dirty_files(struct nilfs_sc_info *sci,
1969 					     struct the_nilfs *nilfs)
1970 {
1971 	struct nilfs_inode_info *ii, *n;
1972 	struct inode *ifile = sci->sc_root->ifile;
1973 
1974 	spin_lock(&nilfs->ns_inode_lock);
1975  retry:
1976 	list_for_each_entry_safe(ii, n, &nilfs->ns_dirty_files, i_dirty) {
1977 		if (!ii->i_bh) {
1978 			struct buffer_head *ibh;
1979 			int err;
1980 
1981 			spin_unlock(&nilfs->ns_inode_lock);
1982 			err = nilfs_ifile_get_inode_block(
1983 				ifile, ii->vfs_inode.i_ino, &ibh);
1984 			if (unlikely(err)) {
1985 				nilfs_warn(sci->sc_super,
1986 					   "log writer: error %d getting inode block (ino=%lu)",
1987 					   err, ii->vfs_inode.i_ino);
1988 				return err;
1989 			}
1990 			spin_lock(&nilfs->ns_inode_lock);
1991 			if (likely(!ii->i_bh))
1992 				ii->i_bh = ibh;
1993 			else
1994 				brelse(ibh);
1995 			goto retry;
1996 		}
1997 
1998 		// Always redirty the buffer to avoid race condition
1999 		mark_buffer_dirty(ii->i_bh);
2000 		nilfs_mdt_mark_dirty(ifile);
2001 
2002 		clear_bit(NILFS_I_QUEUED, &ii->i_state);
2003 		set_bit(NILFS_I_BUSY, &ii->i_state);
2004 		list_move_tail(&ii->i_dirty, &sci->sc_dirty_files);
2005 	}
2006 	spin_unlock(&nilfs->ns_inode_lock);
2007 
2008 	return 0;
2009 }
2010 
2011 static void nilfs_segctor_drop_written_files(struct nilfs_sc_info *sci,
2012 					     struct the_nilfs *nilfs)
2013 {
2014 	struct nilfs_inode_info *ii, *n;
2015 	int during_mount = !(sci->sc_super->s_flags & SB_ACTIVE);
2016 	int defer_iput = false;
2017 
2018 	spin_lock(&nilfs->ns_inode_lock);
2019 	list_for_each_entry_safe(ii, n, &sci->sc_dirty_files, i_dirty) {
2020 		if (!test_and_clear_bit(NILFS_I_UPDATED, &ii->i_state) ||
2021 		    test_bit(NILFS_I_DIRTY, &ii->i_state))
2022 			continue;
2023 
2024 		clear_bit(NILFS_I_BUSY, &ii->i_state);
2025 		brelse(ii->i_bh);
2026 		ii->i_bh = NULL;
2027 		list_del_init(&ii->i_dirty);
2028 		if (!ii->vfs_inode.i_nlink || during_mount) {
2029 			/*
2030 			 * Defer calling iput() to avoid deadlocks if
2031 			 * i_nlink == 0 or mount is not yet finished.
2032 			 */
2033 			list_add_tail(&ii->i_dirty, &sci->sc_iput_queue);
2034 			defer_iput = true;
2035 		} else {
2036 			spin_unlock(&nilfs->ns_inode_lock);
2037 			iput(&ii->vfs_inode);
2038 			spin_lock(&nilfs->ns_inode_lock);
2039 		}
2040 	}
2041 	spin_unlock(&nilfs->ns_inode_lock);
2042 
2043 	if (defer_iput)
2044 		schedule_work(&sci->sc_iput_work);
2045 }
2046 
2047 /*
2048  * Main procedure of segment constructor
2049  */
2050 static int nilfs_segctor_do_construct(struct nilfs_sc_info *sci, int mode)
2051 {
2052 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2053 	int err;
2054 
2055 	if (sb_rdonly(sci->sc_super))
2056 		return -EROFS;
2057 
2058 	nilfs_sc_cstage_set(sci, NILFS_ST_INIT);
2059 	sci->sc_cno = nilfs->ns_cno;
2060 
2061 	err = nilfs_segctor_collect_dirty_files(sci, nilfs);
2062 	if (unlikely(err))
2063 		goto out;
2064 
2065 	if (nilfs_test_metadata_dirty(nilfs, sci->sc_root))
2066 		set_bit(NILFS_SC_DIRTY, &sci->sc_flags);
2067 
2068 	if (nilfs_segctor_clean(sci))
2069 		goto out;
2070 
2071 	do {
2072 		sci->sc_stage.flags &= ~NILFS_CF_HISTORY_MASK;
2073 
2074 		err = nilfs_segctor_begin_construction(sci, nilfs);
2075 		if (unlikely(err))
2076 			goto out;
2077 
2078 		/* Update time stamp */
2079 		sci->sc_seg_ctime = ktime_get_real_seconds();
2080 
2081 		err = nilfs_segctor_collect(sci, nilfs, mode);
2082 		if (unlikely(err))
2083 			goto failed;
2084 
2085 		/* Avoid empty segment */
2086 		if (nilfs_sc_cstage_get(sci) == NILFS_ST_DONE &&
2087 		    nilfs_segbuf_empty(sci->sc_curseg)) {
2088 			nilfs_segctor_abort_construction(sci, nilfs, 1);
2089 			goto out;
2090 		}
2091 
2092 		err = nilfs_segctor_assign(sci, mode);
2093 		if (unlikely(err))
2094 			goto failed;
2095 
2096 		if (sci->sc_stage.flags & NILFS_CF_IFILE_STARTED)
2097 			nilfs_segctor_fill_in_file_bmap(sci);
2098 
2099 		if (mode == SC_LSEG_SR &&
2100 		    nilfs_sc_cstage_get(sci) >= NILFS_ST_CPFILE) {
2101 			err = nilfs_segctor_fill_in_checkpoint(sci);
2102 			if (unlikely(err))
2103 				goto failed_to_write;
2104 
2105 			nilfs_segctor_fill_in_super_root(sci, nilfs);
2106 		}
2107 		nilfs_segctor_update_segusage(sci, nilfs->ns_sufile);
2108 
2109 		/* Write partial segments */
2110 		nilfs_segctor_prepare_write(sci);
2111 
2112 		nilfs_add_checksums_on_logs(&sci->sc_segbufs,
2113 					    nilfs->ns_crc_seed);
2114 
2115 		err = nilfs_segctor_write(sci, nilfs);
2116 		if (unlikely(err))
2117 			goto failed_to_write;
2118 
2119 		if (nilfs_sc_cstage_get(sci) == NILFS_ST_DONE ||
2120 		    nilfs->ns_blocksize_bits != PAGE_SHIFT) {
2121 			/*
2122 			 * At this point, we avoid double buffering
2123 			 * for blocksize < pagesize because page dirty
2124 			 * flag is turned off during write and dirty
2125 			 * buffers are not properly collected for
2126 			 * pages crossing over segments.
2127 			 */
2128 			err = nilfs_segctor_wait(sci);
2129 			if (err)
2130 				goto failed_to_write;
2131 		}
2132 	} while (nilfs_sc_cstage_get(sci) != NILFS_ST_DONE);
2133 
2134  out:
2135 	nilfs_segctor_drop_written_files(sci, nilfs);
2136 	return err;
2137 
2138  failed_to_write:
2139 	if (sci->sc_stage.flags & NILFS_CF_IFILE_STARTED)
2140 		nilfs_redirty_inodes(&sci->sc_dirty_files);
2141 
2142  failed:
2143 	if (nilfs_doing_gc())
2144 		nilfs_redirty_inodes(&sci->sc_gc_inodes);
2145 	nilfs_segctor_abort_construction(sci, nilfs, err);
2146 	goto out;
2147 }
2148 
2149 /**
2150  * nilfs_segctor_start_timer - set timer of background write
2151  * @sci: nilfs_sc_info
2152  *
2153  * If the timer has already been set, it ignores the new request.
2154  * This function MUST be called within a section locking the segment
2155  * semaphore.
2156  */
2157 static void nilfs_segctor_start_timer(struct nilfs_sc_info *sci)
2158 {
2159 	spin_lock(&sci->sc_state_lock);
2160 	if (!(sci->sc_state & NILFS_SEGCTOR_COMMIT)) {
2161 		sci->sc_timer.expires = jiffies + sci->sc_interval;
2162 		add_timer(&sci->sc_timer);
2163 		sci->sc_state |= NILFS_SEGCTOR_COMMIT;
2164 	}
2165 	spin_unlock(&sci->sc_state_lock);
2166 }
2167 
2168 static void nilfs_segctor_do_flush(struct nilfs_sc_info *sci, int bn)
2169 {
2170 	spin_lock(&sci->sc_state_lock);
2171 	if (!(sci->sc_flush_request & BIT(bn))) {
2172 		unsigned long prev_req = sci->sc_flush_request;
2173 
2174 		sci->sc_flush_request |= BIT(bn);
2175 		if (!prev_req)
2176 			wake_up(&sci->sc_wait_daemon);
2177 	}
2178 	spin_unlock(&sci->sc_state_lock);
2179 }
2180 
2181 /**
2182  * nilfs_flush_segment - trigger a segment construction for resource control
2183  * @sb: super block
2184  * @ino: inode number of the file to be flushed out.
2185  */
2186 void nilfs_flush_segment(struct super_block *sb, ino_t ino)
2187 {
2188 	struct the_nilfs *nilfs = sb->s_fs_info;
2189 	struct nilfs_sc_info *sci = nilfs->ns_writer;
2190 
2191 	if (!sci || nilfs_doing_construction())
2192 		return;
2193 	nilfs_segctor_do_flush(sci, NILFS_MDT_INODE(sb, ino) ? ino : 0);
2194 					/* assign bit 0 to data files */
2195 }
2196 
2197 struct nilfs_segctor_wait_request {
2198 	wait_queue_entry_t	wq;
2199 	__u32		seq;
2200 	int		err;
2201 	atomic_t	done;
2202 };
2203 
2204 static int nilfs_segctor_sync(struct nilfs_sc_info *sci)
2205 {
2206 	struct nilfs_segctor_wait_request wait_req;
2207 	int err = 0;
2208 
2209 	spin_lock(&sci->sc_state_lock);
2210 	init_wait(&wait_req.wq);
2211 	wait_req.err = 0;
2212 	atomic_set(&wait_req.done, 0);
2213 	wait_req.seq = ++sci->sc_seq_request;
2214 	spin_unlock(&sci->sc_state_lock);
2215 
2216 	init_waitqueue_entry(&wait_req.wq, current);
2217 	add_wait_queue(&sci->sc_wait_request, &wait_req.wq);
2218 	set_current_state(TASK_INTERRUPTIBLE);
2219 	wake_up(&sci->sc_wait_daemon);
2220 
2221 	for (;;) {
2222 		if (atomic_read(&wait_req.done)) {
2223 			err = wait_req.err;
2224 			break;
2225 		}
2226 		if (!signal_pending(current)) {
2227 			schedule();
2228 			continue;
2229 		}
2230 		err = -ERESTARTSYS;
2231 		break;
2232 	}
2233 	finish_wait(&sci->sc_wait_request, &wait_req.wq);
2234 	return err;
2235 }
2236 
2237 static void nilfs_segctor_wakeup(struct nilfs_sc_info *sci, int err)
2238 {
2239 	struct nilfs_segctor_wait_request *wrq, *n;
2240 	unsigned long flags;
2241 
2242 	spin_lock_irqsave(&sci->sc_wait_request.lock, flags);
2243 	list_for_each_entry_safe(wrq, n, &sci->sc_wait_request.head, wq.entry) {
2244 		if (!atomic_read(&wrq->done) &&
2245 		    nilfs_cnt32_ge(sci->sc_seq_done, wrq->seq)) {
2246 			wrq->err = err;
2247 			atomic_set(&wrq->done, 1);
2248 		}
2249 		if (atomic_read(&wrq->done)) {
2250 			wrq->wq.func(&wrq->wq,
2251 				     TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
2252 				     0, NULL);
2253 		}
2254 	}
2255 	spin_unlock_irqrestore(&sci->sc_wait_request.lock, flags);
2256 }
2257 
2258 /**
2259  * nilfs_construct_segment - construct a logical segment
2260  * @sb: super block
2261  *
2262  * Return Value: On success, 0 is returned. On errors, one of the following
2263  * negative error code is returned.
2264  *
2265  * %-EROFS - Read only filesystem.
2266  *
2267  * %-EIO - I/O error
2268  *
2269  * %-ENOSPC - No space left on device (only in a panic state).
2270  *
2271  * %-ERESTARTSYS - Interrupted.
2272  *
2273  * %-ENOMEM - Insufficient memory available.
2274  */
2275 int nilfs_construct_segment(struct super_block *sb)
2276 {
2277 	struct the_nilfs *nilfs = sb->s_fs_info;
2278 	struct nilfs_sc_info *sci = nilfs->ns_writer;
2279 	struct nilfs_transaction_info *ti;
2280 
2281 	if (sb_rdonly(sb) || unlikely(!sci))
2282 		return -EROFS;
2283 
2284 	/* A call inside transactions causes a deadlock. */
2285 	BUG_ON((ti = current->journal_info) && ti->ti_magic == NILFS_TI_MAGIC);
2286 
2287 	return nilfs_segctor_sync(sci);
2288 }
2289 
2290 /**
2291  * nilfs_construct_dsync_segment - construct a data-only logical segment
2292  * @sb: super block
2293  * @inode: inode whose data blocks should be written out
2294  * @start: start byte offset
2295  * @end: end byte offset (inclusive)
2296  *
2297  * Return Value: On success, 0 is returned. On errors, one of the following
2298  * negative error code is returned.
2299  *
2300  * %-EROFS - Read only filesystem.
2301  *
2302  * %-EIO - I/O error
2303  *
2304  * %-ENOSPC - No space left on device (only in a panic state).
2305  *
2306  * %-ERESTARTSYS - Interrupted.
2307  *
2308  * %-ENOMEM - Insufficient memory available.
2309  */
2310 int nilfs_construct_dsync_segment(struct super_block *sb, struct inode *inode,
2311 				  loff_t start, loff_t end)
2312 {
2313 	struct the_nilfs *nilfs = sb->s_fs_info;
2314 	struct nilfs_sc_info *sci = nilfs->ns_writer;
2315 	struct nilfs_inode_info *ii;
2316 	struct nilfs_transaction_info ti;
2317 	int err = 0;
2318 
2319 	if (sb_rdonly(sb) || unlikely(!sci))
2320 		return -EROFS;
2321 
2322 	nilfs_transaction_lock(sb, &ti, 0);
2323 
2324 	ii = NILFS_I(inode);
2325 	if (test_bit(NILFS_I_INODE_SYNC, &ii->i_state) ||
2326 	    nilfs_test_opt(nilfs, STRICT_ORDER) ||
2327 	    test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags) ||
2328 	    nilfs_discontinued(nilfs)) {
2329 		nilfs_transaction_unlock(sb);
2330 		err = nilfs_segctor_sync(sci);
2331 		return err;
2332 	}
2333 
2334 	spin_lock(&nilfs->ns_inode_lock);
2335 	if (!test_bit(NILFS_I_QUEUED, &ii->i_state) &&
2336 	    !test_bit(NILFS_I_BUSY, &ii->i_state)) {
2337 		spin_unlock(&nilfs->ns_inode_lock);
2338 		nilfs_transaction_unlock(sb);
2339 		return 0;
2340 	}
2341 	spin_unlock(&nilfs->ns_inode_lock);
2342 	sci->sc_dsync_inode = ii;
2343 	sci->sc_dsync_start = start;
2344 	sci->sc_dsync_end = end;
2345 
2346 	err = nilfs_segctor_do_construct(sci, SC_LSEG_DSYNC);
2347 	if (!err)
2348 		nilfs->ns_flushed_device = 0;
2349 
2350 	nilfs_transaction_unlock(sb);
2351 	return err;
2352 }
2353 
2354 #define FLUSH_FILE_BIT	(0x1) /* data file only */
2355 #define FLUSH_DAT_BIT	BIT(NILFS_DAT_INO) /* DAT only */
2356 
2357 /**
2358  * nilfs_segctor_accept - record accepted sequence count of log-write requests
2359  * @sci: segment constructor object
2360  */
2361 static void nilfs_segctor_accept(struct nilfs_sc_info *sci)
2362 {
2363 	spin_lock(&sci->sc_state_lock);
2364 	sci->sc_seq_accepted = sci->sc_seq_request;
2365 	spin_unlock(&sci->sc_state_lock);
2366 	del_timer_sync(&sci->sc_timer);
2367 }
2368 
2369 /**
2370  * nilfs_segctor_notify - notify the result of request to caller threads
2371  * @sci: segment constructor object
2372  * @mode: mode of log forming
2373  * @err: error code to be notified
2374  */
2375 static void nilfs_segctor_notify(struct nilfs_sc_info *sci, int mode, int err)
2376 {
2377 	/* Clear requests (even when the construction failed) */
2378 	spin_lock(&sci->sc_state_lock);
2379 
2380 	if (mode == SC_LSEG_SR) {
2381 		sci->sc_state &= ~NILFS_SEGCTOR_COMMIT;
2382 		sci->sc_seq_done = sci->sc_seq_accepted;
2383 		nilfs_segctor_wakeup(sci, err);
2384 		sci->sc_flush_request = 0;
2385 	} else {
2386 		if (mode == SC_FLUSH_FILE)
2387 			sci->sc_flush_request &= ~FLUSH_FILE_BIT;
2388 		else if (mode == SC_FLUSH_DAT)
2389 			sci->sc_flush_request &= ~FLUSH_DAT_BIT;
2390 
2391 		/* re-enable timer if checkpoint creation was not done */
2392 		if ((sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
2393 		    time_before(jiffies, sci->sc_timer.expires))
2394 			add_timer(&sci->sc_timer);
2395 	}
2396 	spin_unlock(&sci->sc_state_lock);
2397 }
2398 
2399 /**
2400  * nilfs_segctor_construct - form logs and write them to disk
2401  * @sci: segment constructor object
2402  * @mode: mode of log forming
2403  */
2404 static int nilfs_segctor_construct(struct nilfs_sc_info *sci, int mode)
2405 {
2406 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2407 	struct nilfs_super_block **sbp;
2408 	int err = 0;
2409 
2410 	nilfs_segctor_accept(sci);
2411 
2412 	if (nilfs_discontinued(nilfs))
2413 		mode = SC_LSEG_SR;
2414 	if (!nilfs_segctor_confirm(sci))
2415 		err = nilfs_segctor_do_construct(sci, mode);
2416 
2417 	if (likely(!err)) {
2418 		if (mode != SC_FLUSH_DAT)
2419 			atomic_set(&nilfs->ns_ndirtyblks, 0);
2420 		if (test_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags) &&
2421 		    nilfs_discontinued(nilfs)) {
2422 			down_write(&nilfs->ns_sem);
2423 			err = -EIO;
2424 			sbp = nilfs_prepare_super(sci->sc_super,
2425 						  nilfs_sb_will_flip(nilfs));
2426 			if (likely(sbp)) {
2427 				nilfs_set_log_cursor(sbp[0], nilfs);
2428 				err = nilfs_commit_super(sci->sc_super,
2429 							 NILFS_SB_COMMIT);
2430 			}
2431 			up_write(&nilfs->ns_sem);
2432 		}
2433 	}
2434 
2435 	nilfs_segctor_notify(sci, mode, err);
2436 	return err;
2437 }
2438 
2439 static void nilfs_construction_timeout(struct timer_list *t)
2440 {
2441 	struct nilfs_sc_info *sci = from_timer(sci, t, sc_timer);
2442 
2443 	wake_up_process(sci->sc_timer_task);
2444 }
2445 
2446 static void
2447 nilfs_remove_written_gcinodes(struct the_nilfs *nilfs, struct list_head *head)
2448 {
2449 	struct nilfs_inode_info *ii, *n;
2450 
2451 	list_for_each_entry_safe(ii, n, head, i_dirty) {
2452 		if (!test_bit(NILFS_I_UPDATED, &ii->i_state))
2453 			continue;
2454 		list_del_init(&ii->i_dirty);
2455 		truncate_inode_pages(&ii->vfs_inode.i_data, 0);
2456 		nilfs_btnode_cache_clear(ii->i_assoc_inode->i_mapping);
2457 		iput(&ii->vfs_inode);
2458 	}
2459 }
2460 
2461 int nilfs_clean_segments(struct super_block *sb, struct nilfs_argv *argv,
2462 			 void **kbufs)
2463 {
2464 	struct the_nilfs *nilfs = sb->s_fs_info;
2465 	struct nilfs_sc_info *sci = nilfs->ns_writer;
2466 	struct nilfs_transaction_info ti;
2467 	int err;
2468 
2469 	if (unlikely(!sci))
2470 		return -EROFS;
2471 
2472 	nilfs_transaction_lock(sb, &ti, 1);
2473 
2474 	err = nilfs_mdt_save_to_shadow_map(nilfs->ns_dat);
2475 	if (unlikely(err))
2476 		goto out_unlock;
2477 
2478 	err = nilfs_ioctl_prepare_clean_segments(nilfs, argv, kbufs);
2479 	if (unlikely(err)) {
2480 		nilfs_mdt_restore_from_shadow_map(nilfs->ns_dat);
2481 		goto out_unlock;
2482 	}
2483 
2484 	sci->sc_freesegs = kbufs[4];
2485 	sci->sc_nfreesegs = argv[4].v_nmembs;
2486 	list_splice_tail_init(&nilfs->ns_gc_inodes, &sci->sc_gc_inodes);
2487 
2488 	for (;;) {
2489 		err = nilfs_segctor_construct(sci, SC_LSEG_SR);
2490 		nilfs_remove_written_gcinodes(nilfs, &sci->sc_gc_inodes);
2491 
2492 		if (likely(!err))
2493 			break;
2494 
2495 		nilfs_warn(sb, "error %d cleaning segments", err);
2496 		set_current_state(TASK_INTERRUPTIBLE);
2497 		schedule_timeout(sci->sc_interval);
2498 	}
2499 	if (nilfs_test_opt(nilfs, DISCARD)) {
2500 		int ret = nilfs_discard_segments(nilfs, sci->sc_freesegs,
2501 						 sci->sc_nfreesegs);
2502 		if (ret) {
2503 			nilfs_warn(sb,
2504 				   "error %d on discard request, turning discards off for the device",
2505 				   ret);
2506 			nilfs_clear_opt(nilfs, DISCARD);
2507 		}
2508 	}
2509 
2510  out_unlock:
2511 	sci->sc_freesegs = NULL;
2512 	sci->sc_nfreesegs = 0;
2513 	nilfs_mdt_clear_shadow_map(nilfs->ns_dat);
2514 	nilfs_transaction_unlock(sb);
2515 	return err;
2516 }
2517 
2518 static void nilfs_segctor_thread_construct(struct nilfs_sc_info *sci, int mode)
2519 {
2520 	struct nilfs_transaction_info ti;
2521 
2522 	nilfs_transaction_lock(sci->sc_super, &ti, 0);
2523 	nilfs_segctor_construct(sci, mode);
2524 
2525 	/*
2526 	 * Unclosed segment should be retried.  We do this using sc_timer.
2527 	 * Timeout of sc_timer will invoke complete construction which leads
2528 	 * to close the current logical segment.
2529 	 */
2530 	if (test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags))
2531 		nilfs_segctor_start_timer(sci);
2532 
2533 	nilfs_transaction_unlock(sci->sc_super);
2534 }
2535 
2536 static void nilfs_segctor_do_immediate_flush(struct nilfs_sc_info *sci)
2537 {
2538 	int mode = 0;
2539 
2540 	spin_lock(&sci->sc_state_lock);
2541 	mode = (sci->sc_flush_request & FLUSH_DAT_BIT) ?
2542 		SC_FLUSH_DAT : SC_FLUSH_FILE;
2543 	spin_unlock(&sci->sc_state_lock);
2544 
2545 	if (mode) {
2546 		nilfs_segctor_do_construct(sci, mode);
2547 
2548 		spin_lock(&sci->sc_state_lock);
2549 		sci->sc_flush_request &= (mode == SC_FLUSH_FILE) ?
2550 			~FLUSH_FILE_BIT : ~FLUSH_DAT_BIT;
2551 		spin_unlock(&sci->sc_state_lock);
2552 	}
2553 	clear_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags);
2554 }
2555 
2556 static int nilfs_segctor_flush_mode(struct nilfs_sc_info *sci)
2557 {
2558 	if (!test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags) ||
2559 	    time_before(jiffies, sci->sc_lseg_stime + sci->sc_mjcp_freq)) {
2560 		if (!(sci->sc_flush_request & ~FLUSH_FILE_BIT))
2561 			return SC_FLUSH_FILE;
2562 		else if (!(sci->sc_flush_request & ~FLUSH_DAT_BIT))
2563 			return SC_FLUSH_DAT;
2564 	}
2565 	return SC_LSEG_SR;
2566 }
2567 
2568 /**
2569  * nilfs_segctor_thread - main loop of the segment constructor thread.
2570  * @arg: pointer to a struct nilfs_sc_info.
2571  *
2572  * nilfs_segctor_thread() initializes a timer and serves as a daemon
2573  * to execute segment constructions.
2574  */
2575 static int nilfs_segctor_thread(void *arg)
2576 {
2577 	struct nilfs_sc_info *sci = (struct nilfs_sc_info *)arg;
2578 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2579 	int timeout = 0;
2580 
2581 	sci->sc_timer_task = current;
2582 
2583 	/* start sync. */
2584 	sci->sc_task = current;
2585 	wake_up(&sci->sc_wait_task); /* for nilfs_segctor_start_thread() */
2586 	nilfs_info(sci->sc_super,
2587 		   "segctord starting. Construction interval = %lu seconds, CP frequency < %lu seconds",
2588 		   sci->sc_interval / HZ, sci->sc_mjcp_freq / HZ);
2589 
2590 	spin_lock(&sci->sc_state_lock);
2591  loop:
2592 	for (;;) {
2593 		int mode;
2594 
2595 		if (sci->sc_state & NILFS_SEGCTOR_QUIT)
2596 			goto end_thread;
2597 
2598 		if (timeout || sci->sc_seq_request != sci->sc_seq_done)
2599 			mode = SC_LSEG_SR;
2600 		else if (sci->sc_flush_request)
2601 			mode = nilfs_segctor_flush_mode(sci);
2602 		else
2603 			break;
2604 
2605 		spin_unlock(&sci->sc_state_lock);
2606 		nilfs_segctor_thread_construct(sci, mode);
2607 		spin_lock(&sci->sc_state_lock);
2608 		timeout = 0;
2609 	}
2610 
2611 
2612 	if (freezing(current)) {
2613 		spin_unlock(&sci->sc_state_lock);
2614 		try_to_freeze();
2615 		spin_lock(&sci->sc_state_lock);
2616 	} else {
2617 		DEFINE_WAIT(wait);
2618 		int should_sleep = 1;
2619 
2620 		prepare_to_wait(&sci->sc_wait_daemon, &wait,
2621 				TASK_INTERRUPTIBLE);
2622 
2623 		if (sci->sc_seq_request != sci->sc_seq_done)
2624 			should_sleep = 0;
2625 		else if (sci->sc_flush_request)
2626 			should_sleep = 0;
2627 		else if (sci->sc_state & NILFS_SEGCTOR_COMMIT)
2628 			should_sleep = time_before(jiffies,
2629 					sci->sc_timer.expires);
2630 
2631 		if (should_sleep) {
2632 			spin_unlock(&sci->sc_state_lock);
2633 			schedule();
2634 			spin_lock(&sci->sc_state_lock);
2635 		}
2636 		finish_wait(&sci->sc_wait_daemon, &wait);
2637 		timeout = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
2638 			   time_after_eq(jiffies, sci->sc_timer.expires));
2639 
2640 		if (nilfs_sb_dirty(nilfs) && nilfs_sb_need_update(nilfs))
2641 			set_nilfs_discontinued(nilfs);
2642 	}
2643 	goto loop;
2644 
2645  end_thread:
2646 	/* end sync. */
2647 	sci->sc_task = NULL;
2648 	wake_up(&sci->sc_wait_task); /* for nilfs_segctor_kill_thread() */
2649 	spin_unlock(&sci->sc_state_lock);
2650 	return 0;
2651 }
2652 
2653 static int nilfs_segctor_start_thread(struct nilfs_sc_info *sci)
2654 {
2655 	struct task_struct *t;
2656 
2657 	t = kthread_run(nilfs_segctor_thread, sci, "segctord");
2658 	if (IS_ERR(t)) {
2659 		int err = PTR_ERR(t);
2660 
2661 		nilfs_err(sci->sc_super, "error %d creating segctord thread",
2662 			  err);
2663 		return err;
2664 	}
2665 	wait_event(sci->sc_wait_task, sci->sc_task != NULL);
2666 	return 0;
2667 }
2668 
2669 static void nilfs_segctor_kill_thread(struct nilfs_sc_info *sci)
2670 	__acquires(&sci->sc_state_lock)
2671 	__releases(&sci->sc_state_lock)
2672 {
2673 	sci->sc_state |= NILFS_SEGCTOR_QUIT;
2674 
2675 	while (sci->sc_task) {
2676 		wake_up(&sci->sc_wait_daemon);
2677 		spin_unlock(&sci->sc_state_lock);
2678 		wait_event(sci->sc_wait_task, sci->sc_task == NULL);
2679 		spin_lock(&sci->sc_state_lock);
2680 	}
2681 }
2682 
2683 /*
2684  * Setup & clean-up functions
2685  */
2686 static struct nilfs_sc_info *nilfs_segctor_new(struct super_block *sb,
2687 					       struct nilfs_root *root)
2688 {
2689 	struct the_nilfs *nilfs = sb->s_fs_info;
2690 	struct nilfs_sc_info *sci;
2691 
2692 	sci = kzalloc(sizeof(*sci), GFP_KERNEL);
2693 	if (!sci)
2694 		return NULL;
2695 
2696 	sci->sc_super = sb;
2697 
2698 	nilfs_get_root(root);
2699 	sci->sc_root = root;
2700 
2701 	init_waitqueue_head(&sci->sc_wait_request);
2702 	init_waitqueue_head(&sci->sc_wait_daemon);
2703 	init_waitqueue_head(&sci->sc_wait_task);
2704 	spin_lock_init(&sci->sc_state_lock);
2705 	INIT_LIST_HEAD(&sci->sc_dirty_files);
2706 	INIT_LIST_HEAD(&sci->sc_segbufs);
2707 	INIT_LIST_HEAD(&sci->sc_write_logs);
2708 	INIT_LIST_HEAD(&sci->sc_gc_inodes);
2709 	INIT_LIST_HEAD(&sci->sc_iput_queue);
2710 	INIT_WORK(&sci->sc_iput_work, nilfs_iput_work_func);
2711 	timer_setup(&sci->sc_timer, nilfs_construction_timeout, 0);
2712 
2713 	sci->sc_interval = HZ * NILFS_SC_DEFAULT_TIMEOUT;
2714 	sci->sc_mjcp_freq = HZ * NILFS_SC_DEFAULT_SR_FREQ;
2715 	sci->sc_watermark = NILFS_SC_DEFAULT_WATERMARK;
2716 
2717 	if (nilfs->ns_interval)
2718 		sci->sc_interval = HZ * nilfs->ns_interval;
2719 	if (nilfs->ns_watermark)
2720 		sci->sc_watermark = nilfs->ns_watermark;
2721 	return sci;
2722 }
2723 
2724 static void nilfs_segctor_write_out(struct nilfs_sc_info *sci)
2725 {
2726 	int ret, retrycount = NILFS_SC_CLEANUP_RETRY;
2727 
2728 	/*
2729 	 * The segctord thread was stopped and its timer was removed.
2730 	 * But some tasks remain.
2731 	 */
2732 	do {
2733 		struct nilfs_transaction_info ti;
2734 
2735 		nilfs_transaction_lock(sci->sc_super, &ti, 0);
2736 		ret = nilfs_segctor_construct(sci, SC_LSEG_SR);
2737 		nilfs_transaction_unlock(sci->sc_super);
2738 
2739 		flush_work(&sci->sc_iput_work);
2740 
2741 	} while (ret && ret != -EROFS && retrycount-- > 0);
2742 }
2743 
2744 /**
2745  * nilfs_segctor_destroy - destroy the segment constructor.
2746  * @sci: nilfs_sc_info
2747  *
2748  * nilfs_segctor_destroy() kills the segctord thread and frees
2749  * the nilfs_sc_info struct.
2750  * Caller must hold the segment semaphore.
2751  */
2752 static void nilfs_segctor_destroy(struct nilfs_sc_info *sci)
2753 {
2754 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2755 	int flag;
2756 
2757 	up_write(&nilfs->ns_segctor_sem);
2758 
2759 	spin_lock(&sci->sc_state_lock);
2760 	nilfs_segctor_kill_thread(sci);
2761 	flag = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) || sci->sc_flush_request
2762 		|| sci->sc_seq_request != sci->sc_seq_done);
2763 	spin_unlock(&sci->sc_state_lock);
2764 
2765 	if (flush_work(&sci->sc_iput_work))
2766 		flag = true;
2767 
2768 	if (flag || !nilfs_segctor_confirm(sci))
2769 		nilfs_segctor_write_out(sci);
2770 
2771 	if (!list_empty(&sci->sc_dirty_files)) {
2772 		nilfs_warn(sci->sc_super,
2773 			   "disposed unprocessed dirty file(s) when stopping log writer");
2774 		nilfs_dispose_list(nilfs, &sci->sc_dirty_files, 1);
2775 	}
2776 
2777 	if (!list_empty(&sci->sc_iput_queue)) {
2778 		nilfs_warn(sci->sc_super,
2779 			   "disposed unprocessed inode(s) in iput queue when stopping log writer");
2780 		nilfs_dispose_list(nilfs, &sci->sc_iput_queue, 1);
2781 	}
2782 
2783 	WARN_ON(!list_empty(&sci->sc_segbufs));
2784 	WARN_ON(!list_empty(&sci->sc_write_logs));
2785 
2786 	nilfs_put_root(sci->sc_root);
2787 
2788 	down_write(&nilfs->ns_segctor_sem);
2789 
2790 	timer_shutdown_sync(&sci->sc_timer);
2791 	kfree(sci);
2792 }
2793 
2794 /**
2795  * nilfs_attach_log_writer - attach log writer
2796  * @sb: super block instance
2797  * @root: root object of the current filesystem tree
2798  *
2799  * This allocates a log writer object, initializes it, and starts the
2800  * log writer.
2801  *
2802  * Return Value: On success, 0 is returned. On error, one of the following
2803  * negative error code is returned.
2804  *
2805  * %-ENOMEM - Insufficient memory available.
2806  */
2807 int nilfs_attach_log_writer(struct super_block *sb, struct nilfs_root *root)
2808 {
2809 	struct the_nilfs *nilfs = sb->s_fs_info;
2810 	int err;
2811 
2812 	if (nilfs->ns_writer) {
2813 		/*
2814 		 * This happens if the filesystem is made read-only by
2815 		 * __nilfs_error or nilfs_remount and then remounted
2816 		 * read/write.  In these cases, reuse the existing
2817 		 * writer.
2818 		 */
2819 		return 0;
2820 	}
2821 
2822 	nilfs->ns_writer = nilfs_segctor_new(sb, root);
2823 	if (!nilfs->ns_writer)
2824 		return -ENOMEM;
2825 
2826 	inode_attach_wb(nilfs->ns_bdev->bd_inode, NULL);
2827 
2828 	err = nilfs_segctor_start_thread(nilfs->ns_writer);
2829 	if (unlikely(err))
2830 		nilfs_detach_log_writer(sb);
2831 
2832 	return err;
2833 }
2834 
2835 /**
2836  * nilfs_detach_log_writer - destroy log writer
2837  * @sb: super block instance
2838  *
2839  * This kills log writer daemon, frees the log writer object, and
2840  * destroys list of dirty files.
2841  */
2842 void nilfs_detach_log_writer(struct super_block *sb)
2843 {
2844 	struct the_nilfs *nilfs = sb->s_fs_info;
2845 	LIST_HEAD(garbage_list);
2846 
2847 	down_write(&nilfs->ns_segctor_sem);
2848 	if (nilfs->ns_writer) {
2849 		nilfs_segctor_destroy(nilfs->ns_writer);
2850 		nilfs->ns_writer = NULL;
2851 	}
2852 	set_nilfs_purging(nilfs);
2853 
2854 	/* Force to free the list of dirty files */
2855 	spin_lock(&nilfs->ns_inode_lock);
2856 	if (!list_empty(&nilfs->ns_dirty_files)) {
2857 		list_splice_init(&nilfs->ns_dirty_files, &garbage_list);
2858 		nilfs_warn(sb,
2859 			   "disposed unprocessed dirty file(s) when detaching log writer");
2860 	}
2861 	spin_unlock(&nilfs->ns_inode_lock);
2862 	up_write(&nilfs->ns_segctor_sem);
2863 
2864 	nilfs_dispose_list(nilfs, &garbage_list, 1);
2865 	clear_nilfs_purging(nilfs);
2866 }
2867