xref: /openbmc/linux/fs/nilfs2/segment.c (revision 405db98b)
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 (!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 static int nilfs_segctor_feed_segment(struct nilfs_sc_info *sci)
434 {
435 	sci->sc_nblk_this_inc += sci->sc_curseg->sb_sum.nblocks;
436 	if (NILFS_SEGBUF_IS_LAST(sci->sc_curseg, &sci->sc_segbufs))
437 		return -E2BIG; /*
438 				* The current segment is filled up
439 				* (internal code)
440 				*/
441 	sci->sc_curseg = NILFS_NEXT_SEGBUF(sci->sc_curseg);
442 	return nilfs_segctor_reset_segment_buffer(sci);
443 }
444 
445 static int nilfs_segctor_add_super_root(struct nilfs_sc_info *sci)
446 {
447 	struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
448 	int err;
449 
450 	if (segbuf->sb_sum.nblocks >= segbuf->sb_rest_blocks) {
451 		err = nilfs_segctor_feed_segment(sci);
452 		if (err)
453 			return err;
454 		segbuf = sci->sc_curseg;
455 	}
456 	err = nilfs_segbuf_extend_payload(segbuf, &segbuf->sb_super_root);
457 	if (likely(!err))
458 		segbuf->sb_sum.flags |= NILFS_SS_SR;
459 	return err;
460 }
461 
462 /*
463  * Functions for making segment summary and payloads
464  */
465 static int nilfs_segctor_segsum_block_required(
466 	struct nilfs_sc_info *sci, const struct nilfs_segsum_pointer *ssp,
467 	unsigned int binfo_size)
468 {
469 	unsigned int blocksize = sci->sc_super->s_blocksize;
470 	/* Size of finfo and binfo is enough small against blocksize */
471 
472 	return ssp->offset + binfo_size +
473 		(!sci->sc_blk_cnt ? sizeof(struct nilfs_finfo) : 0) >
474 		blocksize;
475 }
476 
477 static void nilfs_segctor_begin_finfo(struct nilfs_sc_info *sci,
478 				      struct inode *inode)
479 {
480 	sci->sc_curseg->sb_sum.nfinfo++;
481 	sci->sc_binfo_ptr = sci->sc_finfo_ptr;
482 	nilfs_segctor_map_segsum_entry(
483 		sci, &sci->sc_binfo_ptr, sizeof(struct nilfs_finfo));
484 
485 	if (NILFS_I(inode)->i_root &&
486 	    !test_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags))
487 		set_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
488 	/* skip finfo */
489 }
490 
491 static void nilfs_segctor_end_finfo(struct nilfs_sc_info *sci,
492 				    struct inode *inode)
493 {
494 	struct nilfs_finfo *finfo;
495 	struct nilfs_inode_info *ii;
496 	struct nilfs_segment_buffer *segbuf;
497 	__u64 cno;
498 
499 	if (sci->sc_blk_cnt == 0)
500 		return;
501 
502 	ii = NILFS_I(inode);
503 
504 	if (test_bit(NILFS_I_GCINODE, &ii->i_state))
505 		cno = ii->i_cno;
506 	else if (NILFS_ROOT_METADATA_FILE(inode->i_ino))
507 		cno = 0;
508 	else
509 		cno = sci->sc_cno;
510 
511 	finfo = nilfs_segctor_map_segsum_entry(sci, &sci->sc_finfo_ptr,
512 						 sizeof(*finfo));
513 	finfo->fi_ino = cpu_to_le64(inode->i_ino);
514 	finfo->fi_nblocks = cpu_to_le32(sci->sc_blk_cnt);
515 	finfo->fi_ndatablk = cpu_to_le32(sci->sc_datablk_cnt);
516 	finfo->fi_cno = cpu_to_le64(cno);
517 
518 	segbuf = sci->sc_curseg;
519 	segbuf->sb_sum.sumbytes = sci->sc_binfo_ptr.offset +
520 		sci->sc_super->s_blocksize * (segbuf->sb_sum.nsumblk - 1);
521 	sci->sc_finfo_ptr = sci->sc_binfo_ptr;
522 	sci->sc_blk_cnt = sci->sc_datablk_cnt = 0;
523 }
524 
525 static int nilfs_segctor_add_file_block(struct nilfs_sc_info *sci,
526 					struct buffer_head *bh,
527 					struct inode *inode,
528 					unsigned int binfo_size)
529 {
530 	struct nilfs_segment_buffer *segbuf;
531 	int required, err = 0;
532 
533  retry:
534 	segbuf = sci->sc_curseg;
535 	required = nilfs_segctor_segsum_block_required(
536 		sci, &sci->sc_binfo_ptr, binfo_size);
537 	if (segbuf->sb_sum.nblocks + required + 1 > segbuf->sb_rest_blocks) {
538 		nilfs_segctor_end_finfo(sci, inode);
539 		err = nilfs_segctor_feed_segment(sci);
540 		if (err)
541 			return err;
542 		goto retry;
543 	}
544 	if (unlikely(required)) {
545 		err = nilfs_segbuf_extend_segsum(segbuf);
546 		if (unlikely(err))
547 			goto failed;
548 	}
549 	if (sci->sc_blk_cnt == 0)
550 		nilfs_segctor_begin_finfo(sci, inode);
551 
552 	nilfs_segctor_map_segsum_entry(sci, &sci->sc_binfo_ptr, binfo_size);
553 	/* Substitution to vblocknr is delayed until update_blocknr() */
554 	nilfs_segbuf_add_file_buffer(segbuf, bh);
555 	sci->sc_blk_cnt++;
556  failed:
557 	return err;
558 }
559 
560 /*
561  * Callback functions that enumerate, mark, and collect dirty blocks
562  */
563 static int nilfs_collect_file_data(struct nilfs_sc_info *sci,
564 				   struct buffer_head *bh, struct inode *inode)
565 {
566 	int err;
567 
568 	err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
569 	if (err < 0)
570 		return err;
571 
572 	err = nilfs_segctor_add_file_block(sci, bh, inode,
573 					   sizeof(struct nilfs_binfo_v));
574 	if (!err)
575 		sci->sc_datablk_cnt++;
576 	return err;
577 }
578 
579 static int nilfs_collect_file_node(struct nilfs_sc_info *sci,
580 				   struct buffer_head *bh,
581 				   struct inode *inode)
582 {
583 	return nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
584 }
585 
586 static int nilfs_collect_file_bmap(struct nilfs_sc_info *sci,
587 				   struct buffer_head *bh,
588 				   struct inode *inode)
589 {
590 	WARN_ON(!buffer_dirty(bh));
591 	return nilfs_segctor_add_file_block(sci, bh, inode, sizeof(__le64));
592 }
593 
594 static void nilfs_write_file_data_binfo(struct nilfs_sc_info *sci,
595 					struct nilfs_segsum_pointer *ssp,
596 					union nilfs_binfo *binfo)
597 {
598 	struct nilfs_binfo_v *binfo_v = nilfs_segctor_map_segsum_entry(
599 		sci, ssp, sizeof(*binfo_v));
600 	*binfo_v = binfo->bi_v;
601 }
602 
603 static void nilfs_write_file_node_binfo(struct nilfs_sc_info *sci,
604 					struct nilfs_segsum_pointer *ssp,
605 					union nilfs_binfo *binfo)
606 {
607 	__le64 *vblocknr = nilfs_segctor_map_segsum_entry(
608 		sci, ssp, sizeof(*vblocknr));
609 	*vblocknr = binfo->bi_v.bi_vblocknr;
610 }
611 
612 static const struct nilfs_sc_operations nilfs_sc_file_ops = {
613 	.collect_data = nilfs_collect_file_data,
614 	.collect_node = nilfs_collect_file_node,
615 	.collect_bmap = nilfs_collect_file_bmap,
616 	.write_data_binfo = nilfs_write_file_data_binfo,
617 	.write_node_binfo = nilfs_write_file_node_binfo,
618 };
619 
620 static int nilfs_collect_dat_data(struct nilfs_sc_info *sci,
621 				  struct buffer_head *bh, struct inode *inode)
622 {
623 	int err;
624 
625 	err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
626 	if (err < 0)
627 		return err;
628 
629 	err = nilfs_segctor_add_file_block(sci, bh, inode, sizeof(__le64));
630 	if (!err)
631 		sci->sc_datablk_cnt++;
632 	return err;
633 }
634 
635 static int nilfs_collect_dat_bmap(struct nilfs_sc_info *sci,
636 				  struct buffer_head *bh, struct inode *inode)
637 {
638 	WARN_ON(!buffer_dirty(bh));
639 	return nilfs_segctor_add_file_block(sci, bh, inode,
640 					    sizeof(struct nilfs_binfo_dat));
641 }
642 
643 static void nilfs_write_dat_data_binfo(struct nilfs_sc_info *sci,
644 				       struct nilfs_segsum_pointer *ssp,
645 				       union nilfs_binfo *binfo)
646 {
647 	__le64 *blkoff = nilfs_segctor_map_segsum_entry(sci, ssp,
648 							  sizeof(*blkoff));
649 	*blkoff = binfo->bi_dat.bi_blkoff;
650 }
651 
652 static void nilfs_write_dat_node_binfo(struct nilfs_sc_info *sci,
653 				       struct nilfs_segsum_pointer *ssp,
654 				       union nilfs_binfo *binfo)
655 {
656 	struct nilfs_binfo_dat *binfo_dat =
657 		nilfs_segctor_map_segsum_entry(sci, ssp, sizeof(*binfo_dat));
658 	*binfo_dat = binfo->bi_dat;
659 }
660 
661 static const struct nilfs_sc_operations nilfs_sc_dat_ops = {
662 	.collect_data = nilfs_collect_dat_data,
663 	.collect_node = nilfs_collect_file_node,
664 	.collect_bmap = nilfs_collect_dat_bmap,
665 	.write_data_binfo = nilfs_write_dat_data_binfo,
666 	.write_node_binfo = nilfs_write_dat_node_binfo,
667 };
668 
669 static const struct nilfs_sc_operations nilfs_sc_dsync_ops = {
670 	.collect_data = nilfs_collect_file_data,
671 	.collect_node = NULL,
672 	.collect_bmap = NULL,
673 	.write_data_binfo = nilfs_write_file_data_binfo,
674 	.write_node_binfo = NULL,
675 };
676 
677 static size_t nilfs_lookup_dirty_data_buffers(struct inode *inode,
678 					      struct list_head *listp,
679 					      size_t nlimit,
680 					      loff_t start, loff_t end)
681 {
682 	struct address_space *mapping = inode->i_mapping;
683 	struct pagevec pvec;
684 	pgoff_t index = 0, last = ULONG_MAX;
685 	size_t ndirties = 0;
686 	int i;
687 
688 	if (unlikely(start != 0 || end != LLONG_MAX)) {
689 		/*
690 		 * A valid range is given for sync-ing data pages. The
691 		 * range is rounded to per-page; extra dirty buffers
692 		 * may be included if blocksize < pagesize.
693 		 */
694 		index = start >> PAGE_SHIFT;
695 		last = end >> PAGE_SHIFT;
696 	}
697 	pagevec_init(&pvec);
698  repeat:
699 	if (unlikely(index > last) ||
700 	    !pagevec_lookup_range_tag(&pvec, mapping, &index, last,
701 				PAGECACHE_TAG_DIRTY))
702 		return ndirties;
703 
704 	for (i = 0; i < pagevec_count(&pvec); i++) {
705 		struct buffer_head *bh, *head;
706 		struct page *page = pvec.pages[i];
707 
708 		lock_page(page);
709 		if (!page_has_buffers(page))
710 			create_empty_buffers(page, i_blocksize(inode), 0);
711 		unlock_page(page);
712 
713 		bh = head = page_buffers(page);
714 		do {
715 			if (!buffer_dirty(bh) || buffer_async_write(bh))
716 				continue;
717 			get_bh(bh);
718 			list_add_tail(&bh->b_assoc_buffers, listp);
719 			ndirties++;
720 			if (unlikely(ndirties >= nlimit)) {
721 				pagevec_release(&pvec);
722 				cond_resched();
723 				return ndirties;
724 			}
725 		} while (bh = bh->b_this_page, bh != head);
726 	}
727 	pagevec_release(&pvec);
728 	cond_resched();
729 	goto repeat;
730 }
731 
732 static void nilfs_lookup_dirty_node_buffers(struct inode *inode,
733 					    struct list_head *listp)
734 {
735 	struct nilfs_inode_info *ii = NILFS_I(inode);
736 	struct address_space *mapping = &ii->i_btnode_cache;
737 	struct pagevec pvec;
738 	struct buffer_head *bh, *head;
739 	unsigned int i;
740 	pgoff_t index = 0;
741 
742 	pagevec_init(&pvec);
743 
744 	while (pagevec_lookup_tag(&pvec, mapping, &index,
745 					PAGECACHE_TAG_DIRTY)) {
746 		for (i = 0; i < pagevec_count(&pvec); i++) {
747 			bh = head = page_buffers(pvec.pages[i]);
748 			do {
749 				if (buffer_dirty(bh) &&
750 						!buffer_async_write(bh)) {
751 					get_bh(bh);
752 					list_add_tail(&bh->b_assoc_buffers,
753 						      listp);
754 				}
755 				bh = bh->b_this_page;
756 			} while (bh != head);
757 		}
758 		pagevec_release(&pvec);
759 		cond_resched();
760 	}
761 }
762 
763 static void nilfs_dispose_list(struct the_nilfs *nilfs,
764 			       struct list_head *head, int force)
765 {
766 	struct nilfs_inode_info *ii, *n;
767 	struct nilfs_inode_info *ivec[SC_N_INODEVEC], **pii;
768 	unsigned int nv = 0;
769 
770 	while (!list_empty(head)) {
771 		spin_lock(&nilfs->ns_inode_lock);
772 		list_for_each_entry_safe(ii, n, head, i_dirty) {
773 			list_del_init(&ii->i_dirty);
774 			if (force) {
775 				if (unlikely(ii->i_bh)) {
776 					brelse(ii->i_bh);
777 					ii->i_bh = NULL;
778 				}
779 			} else if (test_bit(NILFS_I_DIRTY, &ii->i_state)) {
780 				set_bit(NILFS_I_QUEUED, &ii->i_state);
781 				list_add_tail(&ii->i_dirty,
782 					      &nilfs->ns_dirty_files);
783 				continue;
784 			}
785 			ivec[nv++] = ii;
786 			if (nv == SC_N_INODEVEC)
787 				break;
788 		}
789 		spin_unlock(&nilfs->ns_inode_lock);
790 
791 		for (pii = ivec; nv > 0; pii++, nv--)
792 			iput(&(*pii)->vfs_inode);
793 	}
794 }
795 
796 static void nilfs_iput_work_func(struct work_struct *work)
797 {
798 	struct nilfs_sc_info *sci = container_of(work, struct nilfs_sc_info,
799 						 sc_iput_work);
800 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
801 
802 	nilfs_dispose_list(nilfs, &sci->sc_iput_queue, 0);
803 }
804 
805 static int nilfs_test_metadata_dirty(struct the_nilfs *nilfs,
806 				     struct nilfs_root *root)
807 {
808 	int ret = 0;
809 
810 	if (nilfs_mdt_fetch_dirty(root->ifile))
811 		ret++;
812 	if (nilfs_mdt_fetch_dirty(nilfs->ns_cpfile))
813 		ret++;
814 	if (nilfs_mdt_fetch_dirty(nilfs->ns_sufile))
815 		ret++;
816 	if ((ret || nilfs_doing_gc()) && nilfs_mdt_fetch_dirty(nilfs->ns_dat))
817 		ret++;
818 	return ret;
819 }
820 
821 static int nilfs_segctor_clean(struct nilfs_sc_info *sci)
822 {
823 	return list_empty(&sci->sc_dirty_files) &&
824 		!test_bit(NILFS_SC_DIRTY, &sci->sc_flags) &&
825 		sci->sc_nfreesegs == 0 &&
826 		(!nilfs_doing_gc() || list_empty(&sci->sc_gc_inodes));
827 }
828 
829 static int nilfs_segctor_confirm(struct nilfs_sc_info *sci)
830 {
831 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
832 	int ret = 0;
833 
834 	if (nilfs_test_metadata_dirty(nilfs, sci->sc_root))
835 		set_bit(NILFS_SC_DIRTY, &sci->sc_flags);
836 
837 	spin_lock(&nilfs->ns_inode_lock);
838 	if (list_empty(&nilfs->ns_dirty_files) && nilfs_segctor_clean(sci))
839 		ret++;
840 
841 	spin_unlock(&nilfs->ns_inode_lock);
842 	return ret;
843 }
844 
845 static void nilfs_segctor_clear_metadata_dirty(struct nilfs_sc_info *sci)
846 {
847 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
848 
849 	nilfs_mdt_clear_dirty(sci->sc_root->ifile);
850 	nilfs_mdt_clear_dirty(nilfs->ns_cpfile);
851 	nilfs_mdt_clear_dirty(nilfs->ns_sufile);
852 	nilfs_mdt_clear_dirty(nilfs->ns_dat);
853 }
854 
855 static int nilfs_segctor_create_checkpoint(struct nilfs_sc_info *sci)
856 {
857 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
858 	struct buffer_head *bh_cp;
859 	struct nilfs_checkpoint *raw_cp;
860 	int err;
861 
862 	/* XXX: this interface will be changed */
863 	err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, 1,
864 					  &raw_cp, &bh_cp);
865 	if (likely(!err)) {
866 		/*
867 		 * The following code is duplicated with cpfile.  But, it is
868 		 * needed to collect the checkpoint even if it was not newly
869 		 * created.
870 		 */
871 		mark_buffer_dirty(bh_cp);
872 		nilfs_mdt_mark_dirty(nilfs->ns_cpfile);
873 		nilfs_cpfile_put_checkpoint(
874 			nilfs->ns_cpfile, nilfs->ns_cno, bh_cp);
875 	} else
876 		WARN_ON(err == -EINVAL || err == -ENOENT);
877 
878 	return err;
879 }
880 
881 static int nilfs_segctor_fill_in_checkpoint(struct nilfs_sc_info *sci)
882 {
883 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
884 	struct buffer_head *bh_cp;
885 	struct nilfs_checkpoint *raw_cp;
886 	int err;
887 
888 	err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, 0,
889 					  &raw_cp, &bh_cp);
890 	if (unlikely(err)) {
891 		WARN_ON(err == -EINVAL || err == -ENOENT);
892 		goto failed_ibh;
893 	}
894 	raw_cp->cp_snapshot_list.ssl_next = 0;
895 	raw_cp->cp_snapshot_list.ssl_prev = 0;
896 	raw_cp->cp_inodes_count =
897 		cpu_to_le64(atomic64_read(&sci->sc_root->inodes_count));
898 	raw_cp->cp_blocks_count =
899 		cpu_to_le64(atomic64_read(&sci->sc_root->blocks_count));
900 	raw_cp->cp_nblk_inc =
901 		cpu_to_le64(sci->sc_nblk_inc + sci->sc_nblk_this_inc);
902 	raw_cp->cp_create = cpu_to_le64(sci->sc_seg_ctime);
903 	raw_cp->cp_cno = cpu_to_le64(nilfs->ns_cno);
904 
905 	if (test_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags))
906 		nilfs_checkpoint_clear_minor(raw_cp);
907 	else
908 		nilfs_checkpoint_set_minor(raw_cp);
909 
910 	nilfs_write_inode_common(sci->sc_root->ifile,
911 				 &raw_cp->cp_ifile_inode, 1);
912 	nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, bh_cp);
913 	return 0;
914 
915  failed_ibh:
916 	return err;
917 }
918 
919 static void nilfs_fill_in_file_bmap(struct inode *ifile,
920 				    struct nilfs_inode_info *ii)
921 
922 {
923 	struct buffer_head *ibh;
924 	struct nilfs_inode *raw_inode;
925 
926 	if (test_bit(NILFS_I_BMAP, &ii->i_state)) {
927 		ibh = ii->i_bh;
928 		BUG_ON(!ibh);
929 		raw_inode = nilfs_ifile_map_inode(ifile, ii->vfs_inode.i_ino,
930 						  ibh);
931 		nilfs_bmap_write(ii->i_bmap, raw_inode);
932 		nilfs_ifile_unmap_inode(ifile, ii->vfs_inode.i_ino, ibh);
933 	}
934 }
935 
936 static void nilfs_segctor_fill_in_file_bmap(struct nilfs_sc_info *sci)
937 {
938 	struct nilfs_inode_info *ii;
939 
940 	list_for_each_entry(ii, &sci->sc_dirty_files, i_dirty) {
941 		nilfs_fill_in_file_bmap(sci->sc_root->ifile, ii);
942 		set_bit(NILFS_I_COLLECTED, &ii->i_state);
943 	}
944 }
945 
946 static void nilfs_segctor_fill_in_super_root(struct nilfs_sc_info *sci,
947 					     struct the_nilfs *nilfs)
948 {
949 	struct buffer_head *bh_sr;
950 	struct nilfs_super_root *raw_sr;
951 	unsigned int isz, srsz;
952 
953 	bh_sr = NILFS_LAST_SEGBUF(&sci->sc_segbufs)->sb_super_root;
954 	raw_sr = (struct nilfs_super_root *)bh_sr->b_data;
955 	isz = nilfs->ns_inode_size;
956 	srsz = NILFS_SR_BYTES(isz);
957 
958 	raw_sr->sr_bytes = cpu_to_le16(srsz);
959 	raw_sr->sr_nongc_ctime
960 		= cpu_to_le64(nilfs_doing_gc() ?
961 			      nilfs->ns_nongc_ctime : sci->sc_seg_ctime);
962 	raw_sr->sr_flags = 0;
963 
964 	nilfs_write_inode_common(nilfs->ns_dat, (void *)raw_sr +
965 				 NILFS_SR_DAT_OFFSET(isz), 1);
966 	nilfs_write_inode_common(nilfs->ns_cpfile, (void *)raw_sr +
967 				 NILFS_SR_CPFILE_OFFSET(isz), 1);
968 	nilfs_write_inode_common(nilfs->ns_sufile, (void *)raw_sr +
969 				 NILFS_SR_SUFILE_OFFSET(isz), 1);
970 	memset((void *)raw_sr + srsz, 0, nilfs->ns_blocksize - srsz);
971 }
972 
973 static void nilfs_redirty_inodes(struct list_head *head)
974 {
975 	struct nilfs_inode_info *ii;
976 
977 	list_for_each_entry(ii, head, i_dirty) {
978 		if (test_bit(NILFS_I_COLLECTED, &ii->i_state))
979 			clear_bit(NILFS_I_COLLECTED, &ii->i_state);
980 	}
981 }
982 
983 static void nilfs_drop_collected_inodes(struct list_head *head)
984 {
985 	struct nilfs_inode_info *ii;
986 
987 	list_for_each_entry(ii, head, i_dirty) {
988 		if (!test_and_clear_bit(NILFS_I_COLLECTED, &ii->i_state))
989 			continue;
990 
991 		clear_bit(NILFS_I_INODE_SYNC, &ii->i_state);
992 		set_bit(NILFS_I_UPDATED, &ii->i_state);
993 	}
994 }
995 
996 static int nilfs_segctor_apply_buffers(struct nilfs_sc_info *sci,
997 				       struct inode *inode,
998 				       struct list_head *listp,
999 				       int (*collect)(struct nilfs_sc_info *,
1000 						      struct buffer_head *,
1001 						      struct inode *))
1002 {
1003 	struct buffer_head *bh, *n;
1004 	int err = 0;
1005 
1006 	if (collect) {
1007 		list_for_each_entry_safe(bh, n, listp, b_assoc_buffers) {
1008 			list_del_init(&bh->b_assoc_buffers);
1009 			err = collect(sci, bh, inode);
1010 			brelse(bh);
1011 			if (unlikely(err))
1012 				goto dispose_buffers;
1013 		}
1014 		return 0;
1015 	}
1016 
1017  dispose_buffers:
1018 	while (!list_empty(listp)) {
1019 		bh = list_first_entry(listp, struct buffer_head,
1020 				      b_assoc_buffers);
1021 		list_del_init(&bh->b_assoc_buffers);
1022 		brelse(bh);
1023 	}
1024 	return err;
1025 }
1026 
1027 static size_t nilfs_segctor_buffer_rest(struct nilfs_sc_info *sci)
1028 {
1029 	/* Remaining number of blocks within segment buffer */
1030 	return sci->sc_segbuf_nblocks -
1031 		(sci->sc_nblk_this_inc + sci->sc_curseg->sb_sum.nblocks);
1032 }
1033 
1034 static int nilfs_segctor_scan_file(struct nilfs_sc_info *sci,
1035 				   struct inode *inode,
1036 				   const struct nilfs_sc_operations *sc_ops)
1037 {
1038 	LIST_HEAD(data_buffers);
1039 	LIST_HEAD(node_buffers);
1040 	int err;
1041 
1042 	if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
1043 		size_t n, rest = nilfs_segctor_buffer_rest(sci);
1044 
1045 		n = nilfs_lookup_dirty_data_buffers(
1046 			inode, &data_buffers, rest + 1, 0, LLONG_MAX);
1047 		if (n > rest) {
1048 			err = nilfs_segctor_apply_buffers(
1049 				sci, inode, &data_buffers,
1050 				sc_ops->collect_data);
1051 			BUG_ON(!err); /* always receive -E2BIG or true error */
1052 			goto break_or_fail;
1053 		}
1054 	}
1055 	nilfs_lookup_dirty_node_buffers(inode, &node_buffers);
1056 
1057 	if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
1058 		err = nilfs_segctor_apply_buffers(
1059 			sci, inode, &data_buffers, sc_ops->collect_data);
1060 		if (unlikely(err)) {
1061 			/* dispose node list */
1062 			nilfs_segctor_apply_buffers(
1063 				sci, inode, &node_buffers, NULL);
1064 			goto break_or_fail;
1065 		}
1066 		sci->sc_stage.flags |= NILFS_CF_NODE;
1067 	}
1068 	/* Collect node */
1069 	err = nilfs_segctor_apply_buffers(
1070 		sci, inode, &node_buffers, sc_ops->collect_node);
1071 	if (unlikely(err))
1072 		goto break_or_fail;
1073 
1074 	nilfs_bmap_lookup_dirty_buffers(NILFS_I(inode)->i_bmap, &node_buffers);
1075 	err = nilfs_segctor_apply_buffers(
1076 		sci, inode, &node_buffers, sc_ops->collect_bmap);
1077 	if (unlikely(err))
1078 		goto break_or_fail;
1079 
1080 	nilfs_segctor_end_finfo(sci, inode);
1081 	sci->sc_stage.flags &= ~NILFS_CF_NODE;
1082 
1083  break_or_fail:
1084 	return err;
1085 }
1086 
1087 static int nilfs_segctor_scan_file_dsync(struct nilfs_sc_info *sci,
1088 					 struct inode *inode)
1089 {
1090 	LIST_HEAD(data_buffers);
1091 	size_t n, rest = nilfs_segctor_buffer_rest(sci);
1092 	int err;
1093 
1094 	n = nilfs_lookup_dirty_data_buffers(inode, &data_buffers, rest + 1,
1095 					    sci->sc_dsync_start,
1096 					    sci->sc_dsync_end);
1097 
1098 	err = nilfs_segctor_apply_buffers(sci, inode, &data_buffers,
1099 					  nilfs_collect_file_data);
1100 	if (!err) {
1101 		nilfs_segctor_end_finfo(sci, inode);
1102 		BUG_ON(n > rest);
1103 		/* always receive -E2BIG or true error if n > rest */
1104 	}
1105 	return err;
1106 }
1107 
1108 static int nilfs_segctor_collect_blocks(struct nilfs_sc_info *sci, int mode)
1109 {
1110 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
1111 	struct list_head *head;
1112 	struct nilfs_inode_info *ii;
1113 	size_t ndone;
1114 	int err = 0;
1115 
1116 	switch (nilfs_sc_cstage_get(sci)) {
1117 	case NILFS_ST_INIT:
1118 		/* Pre-processes */
1119 		sci->sc_stage.flags = 0;
1120 
1121 		if (!test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags)) {
1122 			sci->sc_nblk_inc = 0;
1123 			sci->sc_curseg->sb_sum.flags = NILFS_SS_LOGBGN;
1124 			if (mode == SC_LSEG_DSYNC) {
1125 				nilfs_sc_cstage_set(sci, NILFS_ST_DSYNC);
1126 				goto dsync_mode;
1127 			}
1128 		}
1129 
1130 		sci->sc_stage.dirty_file_ptr = NULL;
1131 		sci->sc_stage.gc_inode_ptr = NULL;
1132 		if (mode == SC_FLUSH_DAT) {
1133 			nilfs_sc_cstage_set(sci, NILFS_ST_DAT);
1134 			goto dat_stage;
1135 		}
1136 		nilfs_sc_cstage_inc(sci);
1137 		fallthrough;
1138 	case NILFS_ST_GC:
1139 		if (nilfs_doing_gc()) {
1140 			head = &sci->sc_gc_inodes;
1141 			ii = list_prepare_entry(sci->sc_stage.gc_inode_ptr,
1142 						head, i_dirty);
1143 			list_for_each_entry_continue(ii, head, i_dirty) {
1144 				err = nilfs_segctor_scan_file(
1145 					sci, &ii->vfs_inode,
1146 					&nilfs_sc_file_ops);
1147 				if (unlikely(err)) {
1148 					sci->sc_stage.gc_inode_ptr = list_entry(
1149 						ii->i_dirty.prev,
1150 						struct nilfs_inode_info,
1151 						i_dirty);
1152 					goto break_or_fail;
1153 				}
1154 				set_bit(NILFS_I_COLLECTED, &ii->i_state);
1155 			}
1156 			sci->sc_stage.gc_inode_ptr = NULL;
1157 		}
1158 		nilfs_sc_cstage_inc(sci);
1159 		fallthrough;
1160 	case NILFS_ST_FILE:
1161 		head = &sci->sc_dirty_files;
1162 		ii = list_prepare_entry(sci->sc_stage.dirty_file_ptr, head,
1163 					i_dirty);
1164 		list_for_each_entry_continue(ii, head, i_dirty) {
1165 			clear_bit(NILFS_I_DIRTY, &ii->i_state);
1166 
1167 			err = nilfs_segctor_scan_file(sci, &ii->vfs_inode,
1168 						      &nilfs_sc_file_ops);
1169 			if (unlikely(err)) {
1170 				sci->sc_stage.dirty_file_ptr =
1171 					list_entry(ii->i_dirty.prev,
1172 						   struct nilfs_inode_info,
1173 						   i_dirty);
1174 				goto break_or_fail;
1175 			}
1176 			/* sci->sc_stage.dirty_file_ptr = NILFS_I(inode); */
1177 			/* XXX: required ? */
1178 		}
1179 		sci->sc_stage.dirty_file_ptr = NULL;
1180 		if (mode == SC_FLUSH_FILE) {
1181 			nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1182 			return 0;
1183 		}
1184 		nilfs_sc_cstage_inc(sci);
1185 		sci->sc_stage.flags |= NILFS_CF_IFILE_STARTED;
1186 		fallthrough;
1187 	case NILFS_ST_IFILE:
1188 		err = nilfs_segctor_scan_file(sci, sci->sc_root->ifile,
1189 					      &nilfs_sc_file_ops);
1190 		if (unlikely(err))
1191 			break;
1192 		nilfs_sc_cstage_inc(sci);
1193 		/* Creating a checkpoint */
1194 		err = nilfs_segctor_create_checkpoint(sci);
1195 		if (unlikely(err))
1196 			break;
1197 		fallthrough;
1198 	case NILFS_ST_CPFILE:
1199 		err = nilfs_segctor_scan_file(sci, nilfs->ns_cpfile,
1200 					      &nilfs_sc_file_ops);
1201 		if (unlikely(err))
1202 			break;
1203 		nilfs_sc_cstage_inc(sci);
1204 		fallthrough;
1205 	case NILFS_ST_SUFILE:
1206 		err = nilfs_sufile_freev(nilfs->ns_sufile, sci->sc_freesegs,
1207 					 sci->sc_nfreesegs, &ndone);
1208 		if (unlikely(err)) {
1209 			nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1210 						  sci->sc_freesegs, ndone,
1211 						  NULL);
1212 			break;
1213 		}
1214 		sci->sc_stage.flags |= NILFS_CF_SUFREED;
1215 
1216 		err = nilfs_segctor_scan_file(sci, nilfs->ns_sufile,
1217 					      &nilfs_sc_file_ops);
1218 		if (unlikely(err))
1219 			break;
1220 		nilfs_sc_cstage_inc(sci);
1221 		fallthrough;
1222 	case NILFS_ST_DAT:
1223  dat_stage:
1224 		err = nilfs_segctor_scan_file(sci, nilfs->ns_dat,
1225 					      &nilfs_sc_dat_ops);
1226 		if (unlikely(err))
1227 			break;
1228 		if (mode == SC_FLUSH_DAT) {
1229 			nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1230 			return 0;
1231 		}
1232 		nilfs_sc_cstage_inc(sci);
1233 		fallthrough;
1234 	case NILFS_ST_SR:
1235 		if (mode == SC_LSEG_SR) {
1236 			/* Appending a super root */
1237 			err = nilfs_segctor_add_super_root(sci);
1238 			if (unlikely(err))
1239 				break;
1240 		}
1241 		/* End of a logical segment */
1242 		sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
1243 		nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1244 		return 0;
1245 	case NILFS_ST_DSYNC:
1246  dsync_mode:
1247 		sci->sc_curseg->sb_sum.flags |= NILFS_SS_SYNDT;
1248 		ii = sci->sc_dsync_inode;
1249 		if (!test_bit(NILFS_I_BUSY, &ii->i_state))
1250 			break;
1251 
1252 		err = nilfs_segctor_scan_file_dsync(sci, &ii->vfs_inode);
1253 		if (unlikely(err))
1254 			break;
1255 		sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
1256 		nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1257 		return 0;
1258 	case NILFS_ST_DONE:
1259 		return 0;
1260 	default:
1261 		BUG();
1262 	}
1263 
1264  break_or_fail:
1265 	return err;
1266 }
1267 
1268 /**
1269  * nilfs_segctor_begin_construction - setup segment buffer to make a new log
1270  * @sci: nilfs_sc_info
1271  * @nilfs: nilfs object
1272  */
1273 static int nilfs_segctor_begin_construction(struct nilfs_sc_info *sci,
1274 					    struct the_nilfs *nilfs)
1275 {
1276 	struct nilfs_segment_buffer *segbuf, *prev;
1277 	__u64 nextnum;
1278 	int err, alloc = 0;
1279 
1280 	segbuf = nilfs_segbuf_new(sci->sc_super);
1281 	if (unlikely(!segbuf))
1282 		return -ENOMEM;
1283 
1284 	if (list_empty(&sci->sc_write_logs)) {
1285 		nilfs_segbuf_map(segbuf, nilfs->ns_segnum,
1286 				 nilfs->ns_pseg_offset, nilfs);
1287 		if (segbuf->sb_rest_blocks < NILFS_PSEG_MIN_BLOCKS) {
1288 			nilfs_shift_to_next_segment(nilfs);
1289 			nilfs_segbuf_map(segbuf, nilfs->ns_segnum, 0, nilfs);
1290 		}
1291 
1292 		segbuf->sb_sum.seg_seq = nilfs->ns_seg_seq;
1293 		nextnum = nilfs->ns_nextnum;
1294 
1295 		if (nilfs->ns_segnum == nilfs->ns_nextnum)
1296 			/* Start from the head of a new full segment */
1297 			alloc++;
1298 	} else {
1299 		/* Continue logs */
1300 		prev = NILFS_LAST_SEGBUF(&sci->sc_write_logs);
1301 		nilfs_segbuf_map_cont(segbuf, prev);
1302 		segbuf->sb_sum.seg_seq = prev->sb_sum.seg_seq;
1303 		nextnum = prev->sb_nextnum;
1304 
1305 		if (segbuf->sb_rest_blocks < NILFS_PSEG_MIN_BLOCKS) {
1306 			nilfs_segbuf_map(segbuf, prev->sb_nextnum, 0, nilfs);
1307 			segbuf->sb_sum.seg_seq++;
1308 			alloc++;
1309 		}
1310 	}
1311 
1312 	err = nilfs_sufile_mark_dirty(nilfs->ns_sufile, segbuf->sb_segnum);
1313 	if (err)
1314 		goto failed;
1315 
1316 	if (alloc) {
1317 		err = nilfs_sufile_alloc(nilfs->ns_sufile, &nextnum);
1318 		if (err)
1319 			goto failed;
1320 	}
1321 	nilfs_segbuf_set_next_segnum(segbuf, nextnum, nilfs);
1322 
1323 	BUG_ON(!list_empty(&sci->sc_segbufs));
1324 	list_add_tail(&segbuf->sb_list, &sci->sc_segbufs);
1325 	sci->sc_segbuf_nblocks = segbuf->sb_rest_blocks;
1326 	return 0;
1327 
1328  failed:
1329 	nilfs_segbuf_free(segbuf);
1330 	return err;
1331 }
1332 
1333 static int nilfs_segctor_extend_segments(struct nilfs_sc_info *sci,
1334 					 struct the_nilfs *nilfs, int nadd)
1335 {
1336 	struct nilfs_segment_buffer *segbuf, *prev;
1337 	struct inode *sufile = nilfs->ns_sufile;
1338 	__u64 nextnextnum;
1339 	LIST_HEAD(list);
1340 	int err, ret, i;
1341 
1342 	prev = NILFS_LAST_SEGBUF(&sci->sc_segbufs);
1343 	/*
1344 	 * Since the segment specified with nextnum might be allocated during
1345 	 * the previous construction, the buffer including its segusage may
1346 	 * not be dirty.  The following call ensures that the buffer is dirty
1347 	 * and will pin the buffer on memory until the sufile is written.
1348 	 */
1349 	err = nilfs_sufile_mark_dirty(sufile, prev->sb_nextnum);
1350 	if (unlikely(err))
1351 		return err;
1352 
1353 	for (i = 0; i < nadd; i++) {
1354 		/* extend segment info */
1355 		err = -ENOMEM;
1356 		segbuf = nilfs_segbuf_new(sci->sc_super);
1357 		if (unlikely(!segbuf))
1358 			goto failed;
1359 
1360 		/* map this buffer to region of segment on-disk */
1361 		nilfs_segbuf_map(segbuf, prev->sb_nextnum, 0, nilfs);
1362 		sci->sc_segbuf_nblocks += segbuf->sb_rest_blocks;
1363 
1364 		/* allocate the next next full segment */
1365 		err = nilfs_sufile_alloc(sufile, &nextnextnum);
1366 		if (unlikely(err))
1367 			goto failed_segbuf;
1368 
1369 		segbuf->sb_sum.seg_seq = prev->sb_sum.seg_seq + 1;
1370 		nilfs_segbuf_set_next_segnum(segbuf, nextnextnum, nilfs);
1371 
1372 		list_add_tail(&segbuf->sb_list, &list);
1373 		prev = segbuf;
1374 	}
1375 	list_splice_tail(&list, &sci->sc_segbufs);
1376 	return 0;
1377 
1378  failed_segbuf:
1379 	nilfs_segbuf_free(segbuf);
1380  failed:
1381 	list_for_each_entry(segbuf, &list, sb_list) {
1382 		ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1383 		WARN_ON(ret); /* never fails */
1384 	}
1385 	nilfs_destroy_logs(&list);
1386 	return err;
1387 }
1388 
1389 static void nilfs_free_incomplete_logs(struct list_head *logs,
1390 				       struct the_nilfs *nilfs)
1391 {
1392 	struct nilfs_segment_buffer *segbuf, *prev;
1393 	struct inode *sufile = nilfs->ns_sufile;
1394 	int ret;
1395 
1396 	segbuf = NILFS_FIRST_SEGBUF(logs);
1397 	if (nilfs->ns_nextnum != segbuf->sb_nextnum) {
1398 		ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1399 		WARN_ON(ret); /* never fails */
1400 	}
1401 	if (atomic_read(&segbuf->sb_err)) {
1402 		/* Case 1: The first segment failed */
1403 		if (segbuf->sb_pseg_start != segbuf->sb_fseg_start)
1404 			/*
1405 			 * Case 1a:  Partial segment appended into an existing
1406 			 * segment
1407 			 */
1408 			nilfs_terminate_segment(nilfs, segbuf->sb_fseg_start,
1409 						segbuf->sb_fseg_end);
1410 		else /* Case 1b:  New full segment */
1411 			set_nilfs_discontinued(nilfs);
1412 	}
1413 
1414 	prev = segbuf;
1415 	list_for_each_entry_continue(segbuf, logs, sb_list) {
1416 		if (prev->sb_nextnum != segbuf->sb_nextnum) {
1417 			ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1418 			WARN_ON(ret); /* never fails */
1419 		}
1420 		if (atomic_read(&segbuf->sb_err) &&
1421 		    segbuf->sb_segnum != nilfs->ns_nextnum)
1422 			/* Case 2: extended segment (!= next) failed */
1423 			nilfs_sufile_set_error(sufile, segbuf->sb_segnum);
1424 		prev = segbuf;
1425 	}
1426 }
1427 
1428 static void nilfs_segctor_update_segusage(struct nilfs_sc_info *sci,
1429 					  struct inode *sufile)
1430 {
1431 	struct nilfs_segment_buffer *segbuf;
1432 	unsigned long live_blocks;
1433 	int ret;
1434 
1435 	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1436 		live_blocks = segbuf->sb_sum.nblocks +
1437 			(segbuf->sb_pseg_start - segbuf->sb_fseg_start);
1438 		ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1439 						     live_blocks,
1440 						     sci->sc_seg_ctime);
1441 		WARN_ON(ret); /* always succeed because the segusage is dirty */
1442 	}
1443 }
1444 
1445 static void nilfs_cancel_segusage(struct list_head *logs, struct inode *sufile)
1446 {
1447 	struct nilfs_segment_buffer *segbuf;
1448 	int ret;
1449 
1450 	segbuf = NILFS_FIRST_SEGBUF(logs);
1451 	ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1452 					     segbuf->sb_pseg_start -
1453 					     segbuf->sb_fseg_start, 0);
1454 	WARN_ON(ret); /* always succeed because the segusage is dirty */
1455 
1456 	list_for_each_entry_continue(segbuf, logs, sb_list) {
1457 		ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1458 						     0, 0);
1459 		WARN_ON(ret); /* always succeed */
1460 	}
1461 }
1462 
1463 static void nilfs_segctor_truncate_segments(struct nilfs_sc_info *sci,
1464 					    struct nilfs_segment_buffer *last,
1465 					    struct inode *sufile)
1466 {
1467 	struct nilfs_segment_buffer *segbuf = last;
1468 	int ret;
1469 
1470 	list_for_each_entry_continue(segbuf, &sci->sc_segbufs, sb_list) {
1471 		sci->sc_segbuf_nblocks -= segbuf->sb_rest_blocks;
1472 		ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1473 		WARN_ON(ret);
1474 	}
1475 	nilfs_truncate_logs(&sci->sc_segbufs, last);
1476 }
1477 
1478 
1479 static int nilfs_segctor_collect(struct nilfs_sc_info *sci,
1480 				 struct the_nilfs *nilfs, int mode)
1481 {
1482 	struct nilfs_cstage prev_stage = sci->sc_stage;
1483 	int err, nadd = 1;
1484 
1485 	/* Collection retry loop */
1486 	for (;;) {
1487 		sci->sc_nblk_this_inc = 0;
1488 		sci->sc_curseg = NILFS_FIRST_SEGBUF(&sci->sc_segbufs);
1489 
1490 		err = nilfs_segctor_reset_segment_buffer(sci);
1491 		if (unlikely(err))
1492 			goto failed;
1493 
1494 		err = nilfs_segctor_collect_blocks(sci, mode);
1495 		sci->sc_nblk_this_inc += sci->sc_curseg->sb_sum.nblocks;
1496 		if (!err)
1497 			break;
1498 
1499 		if (unlikely(err != -E2BIG))
1500 			goto failed;
1501 
1502 		/* The current segment is filled up */
1503 		if (mode != SC_LSEG_SR ||
1504 		    nilfs_sc_cstage_get(sci) < NILFS_ST_CPFILE)
1505 			break;
1506 
1507 		nilfs_clear_logs(&sci->sc_segbufs);
1508 
1509 		if (sci->sc_stage.flags & NILFS_CF_SUFREED) {
1510 			err = nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1511 							sci->sc_freesegs,
1512 							sci->sc_nfreesegs,
1513 							NULL);
1514 			WARN_ON(err); /* do not happen */
1515 			sci->sc_stage.flags &= ~NILFS_CF_SUFREED;
1516 		}
1517 
1518 		err = nilfs_segctor_extend_segments(sci, nilfs, nadd);
1519 		if (unlikely(err))
1520 			return err;
1521 
1522 		nadd = min_t(int, nadd << 1, SC_MAX_SEGDELTA);
1523 		sci->sc_stage = prev_stage;
1524 	}
1525 	nilfs_segctor_truncate_segments(sci, sci->sc_curseg, nilfs->ns_sufile);
1526 	return 0;
1527 
1528  failed:
1529 	return err;
1530 }
1531 
1532 static void nilfs_list_replace_buffer(struct buffer_head *old_bh,
1533 				      struct buffer_head *new_bh)
1534 {
1535 	BUG_ON(!list_empty(&new_bh->b_assoc_buffers));
1536 
1537 	list_replace_init(&old_bh->b_assoc_buffers, &new_bh->b_assoc_buffers);
1538 	/* The caller must release old_bh */
1539 }
1540 
1541 static int
1542 nilfs_segctor_update_payload_blocknr(struct nilfs_sc_info *sci,
1543 				     struct nilfs_segment_buffer *segbuf,
1544 				     int mode)
1545 {
1546 	struct inode *inode = NULL;
1547 	sector_t blocknr;
1548 	unsigned long nfinfo = segbuf->sb_sum.nfinfo;
1549 	unsigned long nblocks = 0, ndatablk = 0;
1550 	const struct nilfs_sc_operations *sc_op = NULL;
1551 	struct nilfs_segsum_pointer ssp;
1552 	struct nilfs_finfo *finfo = NULL;
1553 	union nilfs_binfo binfo;
1554 	struct buffer_head *bh, *bh_org;
1555 	ino_t ino = 0;
1556 	int err = 0;
1557 
1558 	if (!nfinfo)
1559 		goto out;
1560 
1561 	blocknr = segbuf->sb_pseg_start + segbuf->sb_sum.nsumblk;
1562 	ssp.bh = NILFS_SEGBUF_FIRST_BH(&segbuf->sb_segsum_buffers);
1563 	ssp.offset = sizeof(struct nilfs_segment_summary);
1564 
1565 	list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
1566 		if (bh == segbuf->sb_super_root)
1567 			break;
1568 		if (!finfo) {
1569 			finfo =	nilfs_segctor_map_segsum_entry(
1570 				sci, &ssp, sizeof(*finfo));
1571 			ino = le64_to_cpu(finfo->fi_ino);
1572 			nblocks = le32_to_cpu(finfo->fi_nblocks);
1573 			ndatablk = le32_to_cpu(finfo->fi_ndatablk);
1574 
1575 			inode = bh->b_page->mapping->host;
1576 
1577 			if (mode == SC_LSEG_DSYNC)
1578 				sc_op = &nilfs_sc_dsync_ops;
1579 			else if (ino == NILFS_DAT_INO)
1580 				sc_op = &nilfs_sc_dat_ops;
1581 			else /* file blocks */
1582 				sc_op = &nilfs_sc_file_ops;
1583 		}
1584 		bh_org = bh;
1585 		get_bh(bh_org);
1586 		err = nilfs_bmap_assign(NILFS_I(inode)->i_bmap, &bh, blocknr,
1587 					&binfo);
1588 		if (bh != bh_org)
1589 			nilfs_list_replace_buffer(bh_org, bh);
1590 		brelse(bh_org);
1591 		if (unlikely(err))
1592 			goto failed_bmap;
1593 
1594 		if (ndatablk > 0)
1595 			sc_op->write_data_binfo(sci, &ssp, &binfo);
1596 		else
1597 			sc_op->write_node_binfo(sci, &ssp, &binfo);
1598 
1599 		blocknr++;
1600 		if (--nblocks == 0) {
1601 			finfo = NULL;
1602 			if (--nfinfo == 0)
1603 				break;
1604 		} else if (ndatablk > 0)
1605 			ndatablk--;
1606 	}
1607  out:
1608 	return 0;
1609 
1610  failed_bmap:
1611 	return err;
1612 }
1613 
1614 static int nilfs_segctor_assign(struct nilfs_sc_info *sci, int mode)
1615 {
1616 	struct nilfs_segment_buffer *segbuf;
1617 	int err;
1618 
1619 	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1620 		err = nilfs_segctor_update_payload_blocknr(sci, segbuf, mode);
1621 		if (unlikely(err))
1622 			return err;
1623 		nilfs_segbuf_fill_in_segsum(segbuf);
1624 	}
1625 	return 0;
1626 }
1627 
1628 static void nilfs_begin_page_io(struct page *page)
1629 {
1630 	if (!page || PageWriteback(page))
1631 		/*
1632 		 * For split b-tree node pages, this function may be called
1633 		 * twice.  We ignore the 2nd or later calls by this check.
1634 		 */
1635 		return;
1636 
1637 	lock_page(page);
1638 	clear_page_dirty_for_io(page);
1639 	set_page_writeback(page);
1640 	unlock_page(page);
1641 }
1642 
1643 static void nilfs_segctor_prepare_write(struct nilfs_sc_info *sci)
1644 {
1645 	struct nilfs_segment_buffer *segbuf;
1646 	struct page *bd_page = NULL, *fs_page = NULL;
1647 
1648 	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1649 		struct buffer_head *bh;
1650 
1651 		list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1652 				    b_assoc_buffers) {
1653 			if (bh->b_page != bd_page) {
1654 				if (bd_page) {
1655 					lock_page(bd_page);
1656 					clear_page_dirty_for_io(bd_page);
1657 					set_page_writeback(bd_page);
1658 					unlock_page(bd_page);
1659 				}
1660 				bd_page = bh->b_page;
1661 			}
1662 		}
1663 
1664 		list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1665 				    b_assoc_buffers) {
1666 			set_buffer_async_write(bh);
1667 			if (bh == segbuf->sb_super_root) {
1668 				if (bh->b_page != bd_page) {
1669 					lock_page(bd_page);
1670 					clear_page_dirty_for_io(bd_page);
1671 					set_page_writeback(bd_page);
1672 					unlock_page(bd_page);
1673 					bd_page = bh->b_page;
1674 				}
1675 				break;
1676 			}
1677 			if (bh->b_page != fs_page) {
1678 				nilfs_begin_page_io(fs_page);
1679 				fs_page = bh->b_page;
1680 			}
1681 		}
1682 	}
1683 	if (bd_page) {
1684 		lock_page(bd_page);
1685 		clear_page_dirty_for_io(bd_page);
1686 		set_page_writeback(bd_page);
1687 		unlock_page(bd_page);
1688 	}
1689 	nilfs_begin_page_io(fs_page);
1690 }
1691 
1692 static int nilfs_segctor_write(struct nilfs_sc_info *sci,
1693 			       struct the_nilfs *nilfs)
1694 {
1695 	int ret;
1696 
1697 	ret = nilfs_write_logs(&sci->sc_segbufs, nilfs);
1698 	list_splice_tail_init(&sci->sc_segbufs, &sci->sc_write_logs);
1699 	return ret;
1700 }
1701 
1702 static void nilfs_end_page_io(struct page *page, int err)
1703 {
1704 	if (!page)
1705 		return;
1706 
1707 	if (buffer_nilfs_node(page_buffers(page)) && !PageWriteback(page)) {
1708 		/*
1709 		 * For b-tree node pages, this function may be called twice
1710 		 * or more because they might be split in a segment.
1711 		 */
1712 		if (PageDirty(page)) {
1713 			/*
1714 			 * For pages holding split b-tree node buffers, dirty
1715 			 * flag on the buffers may be cleared discretely.
1716 			 * In that case, the page is once redirtied for
1717 			 * remaining buffers, and it must be cancelled if
1718 			 * all the buffers get cleaned later.
1719 			 */
1720 			lock_page(page);
1721 			if (nilfs_page_buffers_clean(page))
1722 				__nilfs_clear_page_dirty(page);
1723 			unlock_page(page);
1724 		}
1725 		return;
1726 	}
1727 
1728 	if (!err) {
1729 		if (!nilfs_page_buffers_clean(page))
1730 			__set_page_dirty_nobuffers(page);
1731 		ClearPageError(page);
1732 	} else {
1733 		__set_page_dirty_nobuffers(page);
1734 		SetPageError(page);
1735 	}
1736 
1737 	end_page_writeback(page);
1738 }
1739 
1740 static void nilfs_abort_logs(struct list_head *logs, int err)
1741 {
1742 	struct nilfs_segment_buffer *segbuf;
1743 	struct page *bd_page = NULL, *fs_page = NULL;
1744 	struct buffer_head *bh;
1745 
1746 	if (list_empty(logs))
1747 		return;
1748 
1749 	list_for_each_entry(segbuf, logs, sb_list) {
1750 		list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1751 				    b_assoc_buffers) {
1752 			if (bh->b_page != bd_page) {
1753 				if (bd_page)
1754 					end_page_writeback(bd_page);
1755 				bd_page = bh->b_page;
1756 			}
1757 		}
1758 
1759 		list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1760 				    b_assoc_buffers) {
1761 			clear_buffer_async_write(bh);
1762 			if (bh == segbuf->sb_super_root) {
1763 				if (bh->b_page != bd_page) {
1764 					end_page_writeback(bd_page);
1765 					bd_page = bh->b_page;
1766 				}
1767 				break;
1768 			}
1769 			if (bh->b_page != fs_page) {
1770 				nilfs_end_page_io(fs_page, err);
1771 				fs_page = bh->b_page;
1772 			}
1773 		}
1774 	}
1775 	if (bd_page)
1776 		end_page_writeback(bd_page);
1777 
1778 	nilfs_end_page_io(fs_page, err);
1779 }
1780 
1781 static void nilfs_segctor_abort_construction(struct nilfs_sc_info *sci,
1782 					     struct the_nilfs *nilfs, int err)
1783 {
1784 	LIST_HEAD(logs);
1785 	int ret;
1786 
1787 	list_splice_tail_init(&sci->sc_write_logs, &logs);
1788 	ret = nilfs_wait_on_logs(&logs);
1789 	nilfs_abort_logs(&logs, ret ? : err);
1790 
1791 	list_splice_tail_init(&sci->sc_segbufs, &logs);
1792 	nilfs_cancel_segusage(&logs, nilfs->ns_sufile);
1793 	nilfs_free_incomplete_logs(&logs, nilfs);
1794 
1795 	if (sci->sc_stage.flags & NILFS_CF_SUFREED) {
1796 		ret = nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1797 						sci->sc_freesegs,
1798 						sci->sc_nfreesegs,
1799 						NULL);
1800 		WARN_ON(ret); /* do not happen */
1801 	}
1802 
1803 	nilfs_destroy_logs(&logs);
1804 }
1805 
1806 static void nilfs_set_next_segment(struct the_nilfs *nilfs,
1807 				   struct nilfs_segment_buffer *segbuf)
1808 {
1809 	nilfs->ns_segnum = segbuf->sb_segnum;
1810 	nilfs->ns_nextnum = segbuf->sb_nextnum;
1811 	nilfs->ns_pseg_offset = segbuf->sb_pseg_start - segbuf->sb_fseg_start
1812 		+ segbuf->sb_sum.nblocks;
1813 	nilfs->ns_seg_seq = segbuf->sb_sum.seg_seq;
1814 	nilfs->ns_ctime = segbuf->sb_sum.ctime;
1815 }
1816 
1817 static void nilfs_segctor_complete_write(struct nilfs_sc_info *sci)
1818 {
1819 	struct nilfs_segment_buffer *segbuf;
1820 	struct page *bd_page = NULL, *fs_page = NULL;
1821 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
1822 	int update_sr = false;
1823 
1824 	list_for_each_entry(segbuf, &sci->sc_write_logs, sb_list) {
1825 		struct buffer_head *bh;
1826 
1827 		list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1828 				    b_assoc_buffers) {
1829 			set_buffer_uptodate(bh);
1830 			clear_buffer_dirty(bh);
1831 			if (bh->b_page != bd_page) {
1832 				if (bd_page)
1833 					end_page_writeback(bd_page);
1834 				bd_page = bh->b_page;
1835 			}
1836 		}
1837 		/*
1838 		 * We assume that the buffers which belong to the same page
1839 		 * continue over the buffer list.
1840 		 * Under this assumption, the last BHs of pages is
1841 		 * identifiable by the discontinuity of bh->b_page
1842 		 * (page != fs_page).
1843 		 *
1844 		 * For B-tree node blocks, however, this assumption is not
1845 		 * guaranteed.  The cleanup code of B-tree node pages needs
1846 		 * special care.
1847 		 */
1848 		list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1849 				    b_assoc_buffers) {
1850 			const unsigned long set_bits = BIT(BH_Uptodate);
1851 			const unsigned long clear_bits =
1852 				(BIT(BH_Dirty) | BIT(BH_Async_Write) |
1853 				 BIT(BH_Delay) | BIT(BH_NILFS_Volatile) |
1854 				 BIT(BH_NILFS_Redirected));
1855 
1856 			set_mask_bits(&bh->b_state, clear_bits, set_bits);
1857 			if (bh == segbuf->sb_super_root) {
1858 				if (bh->b_page != bd_page) {
1859 					end_page_writeback(bd_page);
1860 					bd_page = bh->b_page;
1861 				}
1862 				update_sr = true;
1863 				break;
1864 			}
1865 			if (bh->b_page != fs_page) {
1866 				nilfs_end_page_io(fs_page, 0);
1867 				fs_page = bh->b_page;
1868 			}
1869 		}
1870 
1871 		if (!nilfs_segbuf_simplex(segbuf)) {
1872 			if (segbuf->sb_sum.flags & NILFS_SS_LOGBGN) {
1873 				set_bit(NILFS_SC_UNCLOSED, &sci->sc_flags);
1874 				sci->sc_lseg_stime = jiffies;
1875 			}
1876 			if (segbuf->sb_sum.flags & NILFS_SS_LOGEND)
1877 				clear_bit(NILFS_SC_UNCLOSED, &sci->sc_flags);
1878 		}
1879 	}
1880 	/*
1881 	 * Since pages may continue over multiple segment buffers,
1882 	 * end of the last page must be checked outside of the loop.
1883 	 */
1884 	if (bd_page)
1885 		end_page_writeback(bd_page);
1886 
1887 	nilfs_end_page_io(fs_page, 0);
1888 
1889 	nilfs_drop_collected_inodes(&sci->sc_dirty_files);
1890 
1891 	if (nilfs_doing_gc())
1892 		nilfs_drop_collected_inodes(&sci->sc_gc_inodes);
1893 	else
1894 		nilfs->ns_nongc_ctime = sci->sc_seg_ctime;
1895 
1896 	sci->sc_nblk_inc += sci->sc_nblk_this_inc;
1897 
1898 	segbuf = NILFS_LAST_SEGBUF(&sci->sc_write_logs);
1899 	nilfs_set_next_segment(nilfs, segbuf);
1900 
1901 	if (update_sr) {
1902 		nilfs->ns_flushed_device = 0;
1903 		nilfs_set_last_segment(nilfs, segbuf->sb_pseg_start,
1904 				       segbuf->sb_sum.seg_seq, nilfs->ns_cno++);
1905 
1906 		clear_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
1907 		clear_bit(NILFS_SC_DIRTY, &sci->sc_flags);
1908 		set_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags);
1909 		nilfs_segctor_clear_metadata_dirty(sci);
1910 	} else
1911 		clear_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags);
1912 }
1913 
1914 static int nilfs_segctor_wait(struct nilfs_sc_info *sci)
1915 {
1916 	int ret;
1917 
1918 	ret = nilfs_wait_on_logs(&sci->sc_write_logs);
1919 	if (!ret) {
1920 		nilfs_segctor_complete_write(sci);
1921 		nilfs_destroy_logs(&sci->sc_write_logs);
1922 	}
1923 	return ret;
1924 }
1925 
1926 static int nilfs_segctor_collect_dirty_files(struct nilfs_sc_info *sci,
1927 					     struct the_nilfs *nilfs)
1928 {
1929 	struct nilfs_inode_info *ii, *n;
1930 	struct inode *ifile = sci->sc_root->ifile;
1931 
1932 	spin_lock(&nilfs->ns_inode_lock);
1933  retry:
1934 	list_for_each_entry_safe(ii, n, &nilfs->ns_dirty_files, i_dirty) {
1935 		if (!ii->i_bh) {
1936 			struct buffer_head *ibh;
1937 			int err;
1938 
1939 			spin_unlock(&nilfs->ns_inode_lock);
1940 			err = nilfs_ifile_get_inode_block(
1941 				ifile, ii->vfs_inode.i_ino, &ibh);
1942 			if (unlikely(err)) {
1943 				nilfs_warn(sci->sc_super,
1944 					   "log writer: error %d getting inode block (ino=%lu)",
1945 					   err, ii->vfs_inode.i_ino);
1946 				return err;
1947 			}
1948 			spin_lock(&nilfs->ns_inode_lock);
1949 			if (likely(!ii->i_bh))
1950 				ii->i_bh = ibh;
1951 			else
1952 				brelse(ibh);
1953 			goto retry;
1954 		}
1955 
1956 		// Always redirty the buffer to avoid race condition
1957 		mark_buffer_dirty(ii->i_bh);
1958 		nilfs_mdt_mark_dirty(ifile);
1959 
1960 		clear_bit(NILFS_I_QUEUED, &ii->i_state);
1961 		set_bit(NILFS_I_BUSY, &ii->i_state);
1962 		list_move_tail(&ii->i_dirty, &sci->sc_dirty_files);
1963 	}
1964 	spin_unlock(&nilfs->ns_inode_lock);
1965 
1966 	return 0;
1967 }
1968 
1969 static void nilfs_segctor_drop_written_files(struct nilfs_sc_info *sci,
1970 					     struct the_nilfs *nilfs)
1971 {
1972 	struct nilfs_inode_info *ii, *n;
1973 	int during_mount = !(sci->sc_super->s_flags & SB_ACTIVE);
1974 	int defer_iput = false;
1975 
1976 	spin_lock(&nilfs->ns_inode_lock);
1977 	list_for_each_entry_safe(ii, n, &sci->sc_dirty_files, i_dirty) {
1978 		if (!test_and_clear_bit(NILFS_I_UPDATED, &ii->i_state) ||
1979 		    test_bit(NILFS_I_DIRTY, &ii->i_state))
1980 			continue;
1981 
1982 		clear_bit(NILFS_I_BUSY, &ii->i_state);
1983 		brelse(ii->i_bh);
1984 		ii->i_bh = NULL;
1985 		list_del_init(&ii->i_dirty);
1986 		if (!ii->vfs_inode.i_nlink || during_mount) {
1987 			/*
1988 			 * Defer calling iput() to avoid deadlocks if
1989 			 * i_nlink == 0 or mount is not yet finished.
1990 			 */
1991 			list_add_tail(&ii->i_dirty, &sci->sc_iput_queue);
1992 			defer_iput = true;
1993 		} else {
1994 			spin_unlock(&nilfs->ns_inode_lock);
1995 			iput(&ii->vfs_inode);
1996 			spin_lock(&nilfs->ns_inode_lock);
1997 		}
1998 	}
1999 	spin_unlock(&nilfs->ns_inode_lock);
2000 
2001 	if (defer_iput)
2002 		schedule_work(&sci->sc_iput_work);
2003 }
2004 
2005 /*
2006  * Main procedure of segment constructor
2007  */
2008 static int nilfs_segctor_do_construct(struct nilfs_sc_info *sci, int mode)
2009 {
2010 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2011 	int err;
2012 
2013 	nilfs_sc_cstage_set(sci, NILFS_ST_INIT);
2014 	sci->sc_cno = nilfs->ns_cno;
2015 
2016 	err = nilfs_segctor_collect_dirty_files(sci, nilfs);
2017 	if (unlikely(err))
2018 		goto out;
2019 
2020 	if (nilfs_test_metadata_dirty(nilfs, sci->sc_root))
2021 		set_bit(NILFS_SC_DIRTY, &sci->sc_flags);
2022 
2023 	if (nilfs_segctor_clean(sci))
2024 		goto out;
2025 
2026 	do {
2027 		sci->sc_stage.flags &= ~NILFS_CF_HISTORY_MASK;
2028 
2029 		err = nilfs_segctor_begin_construction(sci, nilfs);
2030 		if (unlikely(err))
2031 			goto out;
2032 
2033 		/* Update time stamp */
2034 		sci->sc_seg_ctime = ktime_get_real_seconds();
2035 
2036 		err = nilfs_segctor_collect(sci, nilfs, mode);
2037 		if (unlikely(err))
2038 			goto failed;
2039 
2040 		/* Avoid empty segment */
2041 		if (nilfs_sc_cstage_get(sci) == NILFS_ST_DONE &&
2042 		    nilfs_segbuf_empty(sci->sc_curseg)) {
2043 			nilfs_segctor_abort_construction(sci, nilfs, 1);
2044 			goto out;
2045 		}
2046 
2047 		err = nilfs_segctor_assign(sci, mode);
2048 		if (unlikely(err))
2049 			goto failed;
2050 
2051 		if (sci->sc_stage.flags & NILFS_CF_IFILE_STARTED)
2052 			nilfs_segctor_fill_in_file_bmap(sci);
2053 
2054 		if (mode == SC_LSEG_SR &&
2055 		    nilfs_sc_cstage_get(sci) >= NILFS_ST_CPFILE) {
2056 			err = nilfs_segctor_fill_in_checkpoint(sci);
2057 			if (unlikely(err))
2058 				goto failed_to_write;
2059 
2060 			nilfs_segctor_fill_in_super_root(sci, nilfs);
2061 		}
2062 		nilfs_segctor_update_segusage(sci, nilfs->ns_sufile);
2063 
2064 		/* Write partial segments */
2065 		nilfs_segctor_prepare_write(sci);
2066 
2067 		nilfs_add_checksums_on_logs(&sci->sc_segbufs,
2068 					    nilfs->ns_crc_seed);
2069 
2070 		err = nilfs_segctor_write(sci, nilfs);
2071 		if (unlikely(err))
2072 			goto failed_to_write;
2073 
2074 		if (nilfs_sc_cstage_get(sci) == NILFS_ST_DONE ||
2075 		    nilfs->ns_blocksize_bits != PAGE_SHIFT) {
2076 			/*
2077 			 * At this point, we avoid double buffering
2078 			 * for blocksize < pagesize because page dirty
2079 			 * flag is turned off during write and dirty
2080 			 * buffers are not properly collected for
2081 			 * pages crossing over segments.
2082 			 */
2083 			err = nilfs_segctor_wait(sci);
2084 			if (err)
2085 				goto failed_to_write;
2086 		}
2087 	} while (nilfs_sc_cstage_get(sci) != NILFS_ST_DONE);
2088 
2089  out:
2090 	nilfs_segctor_drop_written_files(sci, nilfs);
2091 	return err;
2092 
2093  failed_to_write:
2094 	if (sci->sc_stage.flags & NILFS_CF_IFILE_STARTED)
2095 		nilfs_redirty_inodes(&sci->sc_dirty_files);
2096 
2097  failed:
2098 	if (nilfs_doing_gc())
2099 		nilfs_redirty_inodes(&sci->sc_gc_inodes);
2100 	nilfs_segctor_abort_construction(sci, nilfs, err);
2101 	goto out;
2102 }
2103 
2104 /**
2105  * nilfs_segctor_start_timer - set timer of background write
2106  * @sci: nilfs_sc_info
2107  *
2108  * If the timer has already been set, it ignores the new request.
2109  * This function MUST be called within a section locking the segment
2110  * semaphore.
2111  */
2112 static void nilfs_segctor_start_timer(struct nilfs_sc_info *sci)
2113 {
2114 	spin_lock(&sci->sc_state_lock);
2115 	if (!(sci->sc_state & NILFS_SEGCTOR_COMMIT)) {
2116 		sci->sc_timer.expires = jiffies + sci->sc_interval;
2117 		add_timer(&sci->sc_timer);
2118 		sci->sc_state |= NILFS_SEGCTOR_COMMIT;
2119 	}
2120 	spin_unlock(&sci->sc_state_lock);
2121 }
2122 
2123 static void nilfs_segctor_do_flush(struct nilfs_sc_info *sci, int bn)
2124 {
2125 	spin_lock(&sci->sc_state_lock);
2126 	if (!(sci->sc_flush_request & BIT(bn))) {
2127 		unsigned long prev_req = sci->sc_flush_request;
2128 
2129 		sci->sc_flush_request |= BIT(bn);
2130 		if (!prev_req)
2131 			wake_up(&sci->sc_wait_daemon);
2132 	}
2133 	spin_unlock(&sci->sc_state_lock);
2134 }
2135 
2136 /**
2137  * nilfs_flush_segment - trigger a segment construction for resource control
2138  * @sb: super block
2139  * @ino: inode number of the file to be flushed out.
2140  */
2141 void nilfs_flush_segment(struct super_block *sb, ino_t ino)
2142 {
2143 	struct the_nilfs *nilfs = sb->s_fs_info;
2144 	struct nilfs_sc_info *sci = nilfs->ns_writer;
2145 
2146 	if (!sci || nilfs_doing_construction())
2147 		return;
2148 	nilfs_segctor_do_flush(sci, NILFS_MDT_INODE(sb, ino) ? ino : 0);
2149 					/* assign bit 0 to data files */
2150 }
2151 
2152 struct nilfs_segctor_wait_request {
2153 	wait_queue_entry_t	wq;
2154 	__u32		seq;
2155 	int		err;
2156 	atomic_t	done;
2157 };
2158 
2159 static int nilfs_segctor_sync(struct nilfs_sc_info *sci)
2160 {
2161 	struct nilfs_segctor_wait_request wait_req;
2162 	int err = 0;
2163 
2164 	spin_lock(&sci->sc_state_lock);
2165 	init_wait(&wait_req.wq);
2166 	wait_req.err = 0;
2167 	atomic_set(&wait_req.done, 0);
2168 	wait_req.seq = ++sci->sc_seq_request;
2169 	spin_unlock(&sci->sc_state_lock);
2170 
2171 	init_waitqueue_entry(&wait_req.wq, current);
2172 	add_wait_queue(&sci->sc_wait_request, &wait_req.wq);
2173 	set_current_state(TASK_INTERRUPTIBLE);
2174 	wake_up(&sci->sc_wait_daemon);
2175 
2176 	for (;;) {
2177 		if (atomic_read(&wait_req.done)) {
2178 			err = wait_req.err;
2179 			break;
2180 		}
2181 		if (!signal_pending(current)) {
2182 			schedule();
2183 			continue;
2184 		}
2185 		err = -ERESTARTSYS;
2186 		break;
2187 	}
2188 	finish_wait(&sci->sc_wait_request, &wait_req.wq);
2189 	return err;
2190 }
2191 
2192 static void nilfs_segctor_wakeup(struct nilfs_sc_info *sci, int err)
2193 {
2194 	struct nilfs_segctor_wait_request *wrq, *n;
2195 	unsigned long flags;
2196 
2197 	spin_lock_irqsave(&sci->sc_wait_request.lock, flags);
2198 	list_for_each_entry_safe(wrq, n, &sci->sc_wait_request.head, wq.entry) {
2199 		if (!atomic_read(&wrq->done) &&
2200 		    nilfs_cnt32_ge(sci->sc_seq_done, wrq->seq)) {
2201 			wrq->err = err;
2202 			atomic_set(&wrq->done, 1);
2203 		}
2204 		if (atomic_read(&wrq->done)) {
2205 			wrq->wq.func(&wrq->wq,
2206 				     TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
2207 				     0, NULL);
2208 		}
2209 	}
2210 	spin_unlock_irqrestore(&sci->sc_wait_request.lock, flags);
2211 }
2212 
2213 /**
2214  * nilfs_construct_segment - construct a logical segment
2215  * @sb: super block
2216  *
2217  * Return Value: On success, 0 is returned. On errors, one of the following
2218  * negative error code is returned.
2219  *
2220  * %-EROFS - Read only filesystem.
2221  *
2222  * %-EIO - I/O error
2223  *
2224  * %-ENOSPC - No space left on device (only in a panic state).
2225  *
2226  * %-ERESTARTSYS - Interrupted.
2227  *
2228  * %-ENOMEM - Insufficient memory available.
2229  */
2230 int nilfs_construct_segment(struct super_block *sb)
2231 {
2232 	struct the_nilfs *nilfs = sb->s_fs_info;
2233 	struct nilfs_sc_info *sci = nilfs->ns_writer;
2234 	struct nilfs_transaction_info *ti;
2235 	int err;
2236 
2237 	if (!sci)
2238 		return -EROFS;
2239 
2240 	/* A call inside transactions causes a deadlock. */
2241 	BUG_ON((ti = current->journal_info) && ti->ti_magic == NILFS_TI_MAGIC);
2242 
2243 	err = nilfs_segctor_sync(sci);
2244 	return err;
2245 }
2246 
2247 /**
2248  * nilfs_construct_dsync_segment - construct a data-only logical segment
2249  * @sb: super block
2250  * @inode: inode whose data blocks should be written out
2251  * @start: start byte offset
2252  * @end: end byte offset (inclusive)
2253  *
2254  * Return Value: On success, 0 is returned. On errors, one of the following
2255  * negative error code is returned.
2256  *
2257  * %-EROFS - Read only filesystem.
2258  *
2259  * %-EIO - I/O error
2260  *
2261  * %-ENOSPC - No space left on device (only in a panic state).
2262  *
2263  * %-ERESTARTSYS - Interrupted.
2264  *
2265  * %-ENOMEM - Insufficient memory available.
2266  */
2267 int nilfs_construct_dsync_segment(struct super_block *sb, struct inode *inode,
2268 				  loff_t start, loff_t end)
2269 {
2270 	struct the_nilfs *nilfs = sb->s_fs_info;
2271 	struct nilfs_sc_info *sci = nilfs->ns_writer;
2272 	struct nilfs_inode_info *ii;
2273 	struct nilfs_transaction_info ti;
2274 	int err = 0;
2275 
2276 	if (!sci)
2277 		return -EROFS;
2278 
2279 	nilfs_transaction_lock(sb, &ti, 0);
2280 
2281 	ii = NILFS_I(inode);
2282 	if (test_bit(NILFS_I_INODE_SYNC, &ii->i_state) ||
2283 	    nilfs_test_opt(nilfs, STRICT_ORDER) ||
2284 	    test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags) ||
2285 	    nilfs_discontinued(nilfs)) {
2286 		nilfs_transaction_unlock(sb);
2287 		err = nilfs_segctor_sync(sci);
2288 		return err;
2289 	}
2290 
2291 	spin_lock(&nilfs->ns_inode_lock);
2292 	if (!test_bit(NILFS_I_QUEUED, &ii->i_state) &&
2293 	    !test_bit(NILFS_I_BUSY, &ii->i_state)) {
2294 		spin_unlock(&nilfs->ns_inode_lock);
2295 		nilfs_transaction_unlock(sb);
2296 		return 0;
2297 	}
2298 	spin_unlock(&nilfs->ns_inode_lock);
2299 	sci->sc_dsync_inode = ii;
2300 	sci->sc_dsync_start = start;
2301 	sci->sc_dsync_end = end;
2302 
2303 	err = nilfs_segctor_do_construct(sci, SC_LSEG_DSYNC);
2304 	if (!err)
2305 		nilfs->ns_flushed_device = 0;
2306 
2307 	nilfs_transaction_unlock(sb);
2308 	return err;
2309 }
2310 
2311 #define FLUSH_FILE_BIT	(0x1) /* data file only */
2312 #define FLUSH_DAT_BIT	BIT(NILFS_DAT_INO) /* DAT only */
2313 
2314 /**
2315  * nilfs_segctor_accept - record accepted sequence count of log-write requests
2316  * @sci: segment constructor object
2317  */
2318 static void nilfs_segctor_accept(struct nilfs_sc_info *sci)
2319 {
2320 	spin_lock(&sci->sc_state_lock);
2321 	sci->sc_seq_accepted = sci->sc_seq_request;
2322 	spin_unlock(&sci->sc_state_lock);
2323 	del_timer_sync(&sci->sc_timer);
2324 }
2325 
2326 /**
2327  * nilfs_segctor_notify - notify the result of request to caller threads
2328  * @sci: segment constructor object
2329  * @mode: mode of log forming
2330  * @err: error code to be notified
2331  */
2332 static void nilfs_segctor_notify(struct nilfs_sc_info *sci, int mode, int err)
2333 {
2334 	/* Clear requests (even when the construction failed) */
2335 	spin_lock(&sci->sc_state_lock);
2336 
2337 	if (mode == SC_LSEG_SR) {
2338 		sci->sc_state &= ~NILFS_SEGCTOR_COMMIT;
2339 		sci->sc_seq_done = sci->sc_seq_accepted;
2340 		nilfs_segctor_wakeup(sci, err);
2341 		sci->sc_flush_request = 0;
2342 	} else {
2343 		if (mode == SC_FLUSH_FILE)
2344 			sci->sc_flush_request &= ~FLUSH_FILE_BIT;
2345 		else if (mode == SC_FLUSH_DAT)
2346 			sci->sc_flush_request &= ~FLUSH_DAT_BIT;
2347 
2348 		/* re-enable timer if checkpoint creation was not done */
2349 		if ((sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
2350 		    time_before(jiffies, sci->sc_timer.expires))
2351 			add_timer(&sci->sc_timer);
2352 	}
2353 	spin_unlock(&sci->sc_state_lock);
2354 }
2355 
2356 /**
2357  * nilfs_segctor_construct - form logs and write them to disk
2358  * @sci: segment constructor object
2359  * @mode: mode of log forming
2360  */
2361 static int nilfs_segctor_construct(struct nilfs_sc_info *sci, int mode)
2362 {
2363 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2364 	struct nilfs_super_block **sbp;
2365 	int err = 0;
2366 
2367 	nilfs_segctor_accept(sci);
2368 
2369 	if (nilfs_discontinued(nilfs))
2370 		mode = SC_LSEG_SR;
2371 	if (!nilfs_segctor_confirm(sci))
2372 		err = nilfs_segctor_do_construct(sci, mode);
2373 
2374 	if (likely(!err)) {
2375 		if (mode != SC_FLUSH_DAT)
2376 			atomic_set(&nilfs->ns_ndirtyblks, 0);
2377 		if (test_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags) &&
2378 		    nilfs_discontinued(nilfs)) {
2379 			down_write(&nilfs->ns_sem);
2380 			err = -EIO;
2381 			sbp = nilfs_prepare_super(sci->sc_super,
2382 						  nilfs_sb_will_flip(nilfs));
2383 			if (likely(sbp)) {
2384 				nilfs_set_log_cursor(sbp[0], nilfs);
2385 				err = nilfs_commit_super(sci->sc_super,
2386 							 NILFS_SB_COMMIT);
2387 			}
2388 			up_write(&nilfs->ns_sem);
2389 		}
2390 	}
2391 
2392 	nilfs_segctor_notify(sci, mode, err);
2393 	return err;
2394 }
2395 
2396 static void nilfs_construction_timeout(struct timer_list *t)
2397 {
2398 	struct nilfs_sc_info *sci = from_timer(sci, t, sc_timer);
2399 
2400 	wake_up_process(sci->sc_timer_task);
2401 }
2402 
2403 static void
2404 nilfs_remove_written_gcinodes(struct the_nilfs *nilfs, struct list_head *head)
2405 {
2406 	struct nilfs_inode_info *ii, *n;
2407 
2408 	list_for_each_entry_safe(ii, n, head, i_dirty) {
2409 		if (!test_bit(NILFS_I_UPDATED, &ii->i_state))
2410 			continue;
2411 		list_del_init(&ii->i_dirty);
2412 		truncate_inode_pages(&ii->vfs_inode.i_data, 0);
2413 		nilfs_btnode_cache_clear(&ii->i_btnode_cache);
2414 		iput(&ii->vfs_inode);
2415 	}
2416 }
2417 
2418 int nilfs_clean_segments(struct super_block *sb, struct nilfs_argv *argv,
2419 			 void **kbufs)
2420 {
2421 	struct the_nilfs *nilfs = sb->s_fs_info;
2422 	struct nilfs_sc_info *sci = nilfs->ns_writer;
2423 	struct nilfs_transaction_info ti;
2424 	int err;
2425 
2426 	if (unlikely(!sci))
2427 		return -EROFS;
2428 
2429 	nilfs_transaction_lock(sb, &ti, 1);
2430 
2431 	err = nilfs_mdt_save_to_shadow_map(nilfs->ns_dat);
2432 	if (unlikely(err))
2433 		goto out_unlock;
2434 
2435 	err = nilfs_ioctl_prepare_clean_segments(nilfs, argv, kbufs);
2436 	if (unlikely(err)) {
2437 		nilfs_mdt_restore_from_shadow_map(nilfs->ns_dat);
2438 		goto out_unlock;
2439 	}
2440 
2441 	sci->sc_freesegs = kbufs[4];
2442 	sci->sc_nfreesegs = argv[4].v_nmembs;
2443 	list_splice_tail_init(&nilfs->ns_gc_inodes, &sci->sc_gc_inodes);
2444 
2445 	for (;;) {
2446 		err = nilfs_segctor_construct(sci, SC_LSEG_SR);
2447 		nilfs_remove_written_gcinodes(nilfs, &sci->sc_gc_inodes);
2448 
2449 		if (likely(!err))
2450 			break;
2451 
2452 		nilfs_warn(sb, "error %d cleaning segments", err);
2453 		set_current_state(TASK_INTERRUPTIBLE);
2454 		schedule_timeout(sci->sc_interval);
2455 	}
2456 	if (nilfs_test_opt(nilfs, DISCARD)) {
2457 		int ret = nilfs_discard_segments(nilfs, sci->sc_freesegs,
2458 						 sci->sc_nfreesegs);
2459 		if (ret) {
2460 			nilfs_warn(sb,
2461 				   "error %d on discard request, turning discards off for the device",
2462 				   ret);
2463 			nilfs_clear_opt(nilfs, DISCARD);
2464 		}
2465 	}
2466 
2467  out_unlock:
2468 	sci->sc_freesegs = NULL;
2469 	sci->sc_nfreesegs = 0;
2470 	nilfs_mdt_clear_shadow_map(nilfs->ns_dat);
2471 	nilfs_transaction_unlock(sb);
2472 	return err;
2473 }
2474 
2475 static void nilfs_segctor_thread_construct(struct nilfs_sc_info *sci, int mode)
2476 {
2477 	struct nilfs_transaction_info ti;
2478 
2479 	nilfs_transaction_lock(sci->sc_super, &ti, 0);
2480 	nilfs_segctor_construct(sci, mode);
2481 
2482 	/*
2483 	 * Unclosed segment should be retried.  We do this using sc_timer.
2484 	 * Timeout of sc_timer will invoke complete construction which leads
2485 	 * to close the current logical segment.
2486 	 */
2487 	if (test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags))
2488 		nilfs_segctor_start_timer(sci);
2489 
2490 	nilfs_transaction_unlock(sci->sc_super);
2491 }
2492 
2493 static void nilfs_segctor_do_immediate_flush(struct nilfs_sc_info *sci)
2494 {
2495 	int mode = 0;
2496 
2497 	spin_lock(&sci->sc_state_lock);
2498 	mode = (sci->sc_flush_request & FLUSH_DAT_BIT) ?
2499 		SC_FLUSH_DAT : SC_FLUSH_FILE;
2500 	spin_unlock(&sci->sc_state_lock);
2501 
2502 	if (mode) {
2503 		nilfs_segctor_do_construct(sci, mode);
2504 
2505 		spin_lock(&sci->sc_state_lock);
2506 		sci->sc_flush_request &= (mode == SC_FLUSH_FILE) ?
2507 			~FLUSH_FILE_BIT : ~FLUSH_DAT_BIT;
2508 		spin_unlock(&sci->sc_state_lock);
2509 	}
2510 	clear_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags);
2511 }
2512 
2513 static int nilfs_segctor_flush_mode(struct nilfs_sc_info *sci)
2514 {
2515 	if (!test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags) ||
2516 	    time_before(jiffies, sci->sc_lseg_stime + sci->sc_mjcp_freq)) {
2517 		if (!(sci->sc_flush_request & ~FLUSH_FILE_BIT))
2518 			return SC_FLUSH_FILE;
2519 		else if (!(sci->sc_flush_request & ~FLUSH_DAT_BIT))
2520 			return SC_FLUSH_DAT;
2521 	}
2522 	return SC_LSEG_SR;
2523 }
2524 
2525 /**
2526  * nilfs_segctor_thread - main loop of the segment constructor thread.
2527  * @arg: pointer to a struct nilfs_sc_info.
2528  *
2529  * nilfs_segctor_thread() initializes a timer and serves as a daemon
2530  * to execute segment constructions.
2531  */
2532 static int nilfs_segctor_thread(void *arg)
2533 {
2534 	struct nilfs_sc_info *sci = (struct nilfs_sc_info *)arg;
2535 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2536 	int timeout = 0;
2537 
2538 	sci->sc_timer_task = current;
2539 
2540 	/* start sync. */
2541 	sci->sc_task = current;
2542 	wake_up(&sci->sc_wait_task); /* for nilfs_segctor_start_thread() */
2543 	nilfs_info(sci->sc_super,
2544 		   "segctord starting. Construction interval = %lu seconds, CP frequency < %lu seconds",
2545 		   sci->sc_interval / HZ, sci->sc_mjcp_freq / HZ);
2546 
2547 	spin_lock(&sci->sc_state_lock);
2548  loop:
2549 	for (;;) {
2550 		int mode;
2551 
2552 		if (sci->sc_state & NILFS_SEGCTOR_QUIT)
2553 			goto end_thread;
2554 
2555 		if (timeout || sci->sc_seq_request != sci->sc_seq_done)
2556 			mode = SC_LSEG_SR;
2557 		else if (sci->sc_flush_request)
2558 			mode = nilfs_segctor_flush_mode(sci);
2559 		else
2560 			break;
2561 
2562 		spin_unlock(&sci->sc_state_lock);
2563 		nilfs_segctor_thread_construct(sci, mode);
2564 		spin_lock(&sci->sc_state_lock);
2565 		timeout = 0;
2566 	}
2567 
2568 
2569 	if (freezing(current)) {
2570 		spin_unlock(&sci->sc_state_lock);
2571 		try_to_freeze();
2572 		spin_lock(&sci->sc_state_lock);
2573 	} else {
2574 		DEFINE_WAIT(wait);
2575 		int should_sleep = 1;
2576 
2577 		prepare_to_wait(&sci->sc_wait_daemon, &wait,
2578 				TASK_INTERRUPTIBLE);
2579 
2580 		if (sci->sc_seq_request != sci->sc_seq_done)
2581 			should_sleep = 0;
2582 		else if (sci->sc_flush_request)
2583 			should_sleep = 0;
2584 		else if (sci->sc_state & NILFS_SEGCTOR_COMMIT)
2585 			should_sleep = time_before(jiffies,
2586 					sci->sc_timer.expires);
2587 
2588 		if (should_sleep) {
2589 			spin_unlock(&sci->sc_state_lock);
2590 			schedule();
2591 			spin_lock(&sci->sc_state_lock);
2592 		}
2593 		finish_wait(&sci->sc_wait_daemon, &wait);
2594 		timeout = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
2595 			   time_after_eq(jiffies, sci->sc_timer.expires));
2596 
2597 		if (nilfs_sb_dirty(nilfs) && nilfs_sb_need_update(nilfs))
2598 			set_nilfs_discontinued(nilfs);
2599 	}
2600 	goto loop;
2601 
2602  end_thread:
2603 	spin_unlock(&sci->sc_state_lock);
2604 
2605 	/* end sync. */
2606 	sci->sc_task = NULL;
2607 	wake_up(&sci->sc_wait_task); /* for nilfs_segctor_kill_thread() */
2608 	return 0;
2609 }
2610 
2611 static int nilfs_segctor_start_thread(struct nilfs_sc_info *sci)
2612 {
2613 	struct task_struct *t;
2614 
2615 	t = kthread_run(nilfs_segctor_thread, sci, "segctord");
2616 	if (IS_ERR(t)) {
2617 		int err = PTR_ERR(t);
2618 
2619 		nilfs_err(sci->sc_super, "error %d creating segctord thread",
2620 			  err);
2621 		return err;
2622 	}
2623 	wait_event(sci->sc_wait_task, sci->sc_task != NULL);
2624 	return 0;
2625 }
2626 
2627 static void nilfs_segctor_kill_thread(struct nilfs_sc_info *sci)
2628 	__acquires(&sci->sc_state_lock)
2629 	__releases(&sci->sc_state_lock)
2630 {
2631 	sci->sc_state |= NILFS_SEGCTOR_QUIT;
2632 
2633 	while (sci->sc_task) {
2634 		wake_up(&sci->sc_wait_daemon);
2635 		spin_unlock(&sci->sc_state_lock);
2636 		wait_event(sci->sc_wait_task, sci->sc_task == NULL);
2637 		spin_lock(&sci->sc_state_lock);
2638 	}
2639 }
2640 
2641 /*
2642  * Setup & clean-up functions
2643  */
2644 static struct nilfs_sc_info *nilfs_segctor_new(struct super_block *sb,
2645 					       struct nilfs_root *root)
2646 {
2647 	struct the_nilfs *nilfs = sb->s_fs_info;
2648 	struct nilfs_sc_info *sci;
2649 
2650 	sci = kzalloc(sizeof(*sci), GFP_KERNEL);
2651 	if (!sci)
2652 		return NULL;
2653 
2654 	sci->sc_super = sb;
2655 
2656 	nilfs_get_root(root);
2657 	sci->sc_root = root;
2658 
2659 	init_waitqueue_head(&sci->sc_wait_request);
2660 	init_waitqueue_head(&sci->sc_wait_daemon);
2661 	init_waitqueue_head(&sci->sc_wait_task);
2662 	spin_lock_init(&sci->sc_state_lock);
2663 	INIT_LIST_HEAD(&sci->sc_dirty_files);
2664 	INIT_LIST_HEAD(&sci->sc_segbufs);
2665 	INIT_LIST_HEAD(&sci->sc_write_logs);
2666 	INIT_LIST_HEAD(&sci->sc_gc_inodes);
2667 	INIT_LIST_HEAD(&sci->sc_iput_queue);
2668 	INIT_WORK(&sci->sc_iput_work, nilfs_iput_work_func);
2669 	timer_setup(&sci->sc_timer, nilfs_construction_timeout, 0);
2670 
2671 	sci->sc_interval = HZ * NILFS_SC_DEFAULT_TIMEOUT;
2672 	sci->sc_mjcp_freq = HZ * NILFS_SC_DEFAULT_SR_FREQ;
2673 	sci->sc_watermark = NILFS_SC_DEFAULT_WATERMARK;
2674 
2675 	if (nilfs->ns_interval)
2676 		sci->sc_interval = HZ * nilfs->ns_interval;
2677 	if (nilfs->ns_watermark)
2678 		sci->sc_watermark = nilfs->ns_watermark;
2679 	return sci;
2680 }
2681 
2682 static void nilfs_segctor_write_out(struct nilfs_sc_info *sci)
2683 {
2684 	int ret, retrycount = NILFS_SC_CLEANUP_RETRY;
2685 
2686 	/*
2687 	 * The segctord thread was stopped and its timer was removed.
2688 	 * But some tasks remain.
2689 	 */
2690 	do {
2691 		struct nilfs_transaction_info ti;
2692 
2693 		nilfs_transaction_lock(sci->sc_super, &ti, 0);
2694 		ret = nilfs_segctor_construct(sci, SC_LSEG_SR);
2695 		nilfs_transaction_unlock(sci->sc_super);
2696 
2697 		flush_work(&sci->sc_iput_work);
2698 
2699 	} while (ret && retrycount-- > 0);
2700 }
2701 
2702 /**
2703  * nilfs_segctor_destroy - destroy the segment constructor.
2704  * @sci: nilfs_sc_info
2705  *
2706  * nilfs_segctor_destroy() kills the segctord thread and frees
2707  * the nilfs_sc_info struct.
2708  * Caller must hold the segment semaphore.
2709  */
2710 static void nilfs_segctor_destroy(struct nilfs_sc_info *sci)
2711 {
2712 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2713 	int flag;
2714 
2715 	up_write(&nilfs->ns_segctor_sem);
2716 
2717 	spin_lock(&sci->sc_state_lock);
2718 	nilfs_segctor_kill_thread(sci);
2719 	flag = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) || sci->sc_flush_request
2720 		|| sci->sc_seq_request != sci->sc_seq_done);
2721 	spin_unlock(&sci->sc_state_lock);
2722 
2723 	if (flush_work(&sci->sc_iput_work))
2724 		flag = true;
2725 
2726 	if (flag || !nilfs_segctor_confirm(sci))
2727 		nilfs_segctor_write_out(sci);
2728 
2729 	if (!list_empty(&sci->sc_dirty_files)) {
2730 		nilfs_warn(sci->sc_super,
2731 			   "disposed unprocessed dirty file(s) when stopping log writer");
2732 		nilfs_dispose_list(nilfs, &sci->sc_dirty_files, 1);
2733 	}
2734 
2735 	if (!list_empty(&sci->sc_iput_queue)) {
2736 		nilfs_warn(sci->sc_super,
2737 			   "disposed unprocessed inode(s) in iput queue when stopping log writer");
2738 		nilfs_dispose_list(nilfs, &sci->sc_iput_queue, 1);
2739 	}
2740 
2741 	WARN_ON(!list_empty(&sci->sc_segbufs));
2742 	WARN_ON(!list_empty(&sci->sc_write_logs));
2743 
2744 	nilfs_put_root(sci->sc_root);
2745 
2746 	down_write(&nilfs->ns_segctor_sem);
2747 
2748 	del_timer_sync(&sci->sc_timer);
2749 	kfree(sci);
2750 }
2751 
2752 /**
2753  * nilfs_attach_log_writer - attach log writer
2754  * @sb: super block instance
2755  * @root: root object of the current filesystem tree
2756  *
2757  * This allocates a log writer object, initializes it, and starts the
2758  * log writer.
2759  *
2760  * Return Value: On success, 0 is returned. On error, one of the following
2761  * negative error code is returned.
2762  *
2763  * %-ENOMEM - Insufficient memory available.
2764  */
2765 int nilfs_attach_log_writer(struct super_block *sb, struct nilfs_root *root)
2766 {
2767 	struct the_nilfs *nilfs = sb->s_fs_info;
2768 	int err;
2769 
2770 	if (nilfs->ns_writer) {
2771 		/*
2772 		 * This happens if the filesystem was remounted
2773 		 * read/write after nilfs_error degenerated it into a
2774 		 * read-only mount.
2775 		 */
2776 		nilfs_detach_log_writer(sb);
2777 	}
2778 
2779 	nilfs->ns_writer = nilfs_segctor_new(sb, root);
2780 	if (!nilfs->ns_writer)
2781 		return -ENOMEM;
2782 
2783 	inode_attach_wb(nilfs->ns_bdev->bd_inode, NULL);
2784 
2785 	err = nilfs_segctor_start_thread(nilfs->ns_writer);
2786 	if (err) {
2787 		kfree(nilfs->ns_writer);
2788 		nilfs->ns_writer = NULL;
2789 	}
2790 	return err;
2791 }
2792 
2793 /**
2794  * nilfs_detach_log_writer - destroy log writer
2795  * @sb: super block instance
2796  *
2797  * This kills log writer daemon, frees the log writer object, and
2798  * destroys list of dirty files.
2799  */
2800 void nilfs_detach_log_writer(struct super_block *sb)
2801 {
2802 	struct the_nilfs *nilfs = sb->s_fs_info;
2803 	LIST_HEAD(garbage_list);
2804 
2805 	down_write(&nilfs->ns_segctor_sem);
2806 	if (nilfs->ns_writer) {
2807 		nilfs_segctor_destroy(nilfs->ns_writer);
2808 		nilfs->ns_writer = NULL;
2809 	}
2810 
2811 	/* Force to free the list of dirty files */
2812 	spin_lock(&nilfs->ns_inode_lock);
2813 	if (!list_empty(&nilfs->ns_dirty_files)) {
2814 		list_splice_init(&nilfs->ns_dirty_files, &garbage_list);
2815 		nilfs_warn(sb,
2816 			   "disposed unprocessed dirty file(s) when detaching log writer");
2817 	}
2818 	spin_unlock(&nilfs->ns_inode_lock);
2819 	up_write(&nilfs->ns_segctor_sem);
2820 
2821 	nilfs_dispose_list(nilfs, &garbage_list, 1);
2822 }
2823