xref: /linux/fs/nilfs2/segment.c (revision 2634682fdffd9ba6e74b76be8aa91cf8b2e05c41)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * segment.c - 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_gt(a, b)   \
138 	(typecheck(__u32, a) && typecheck(__u32, b) && \
139 	 ((__s32)(b) - (__s32)(a) < 0))
140 #define nilfs_cnt32_ge(a, b)   \
141 	(typecheck(__u32, a) && typecheck(__u32, b) && \
142 	 ((__s32)(a) - (__s32)(b) >= 0))
143 #define nilfs_cnt32_lt(a, b)  nilfs_cnt32_gt(b, a)
144 #define nilfs_cnt32_le(a, b)  nilfs_cnt32_ge(b, a)
145 
146 static int nilfs_prepare_segment_lock(struct super_block *sb,
147 				      struct nilfs_transaction_info *ti)
148 {
149 	struct nilfs_transaction_info *cur_ti = current->journal_info;
150 	void *save = NULL;
151 
152 	if (cur_ti) {
153 		if (cur_ti->ti_magic == NILFS_TI_MAGIC)
154 			return ++cur_ti->ti_count;
155 
156 		/*
157 		 * If journal_info field is occupied by other FS,
158 		 * it is saved and will be restored on
159 		 * nilfs_transaction_commit().
160 		 */
161 		nilfs_warn(sb, "journal info from a different FS");
162 		save = current->journal_info;
163 	}
164 	if (!ti) {
165 		ti = kmem_cache_alloc(nilfs_transaction_cachep, GFP_NOFS);
166 		if (!ti)
167 			return -ENOMEM;
168 		ti->ti_flags = NILFS_TI_DYNAMIC_ALLOC;
169 	} else {
170 		ti->ti_flags = 0;
171 	}
172 	ti->ti_count = 0;
173 	ti->ti_save = save;
174 	ti->ti_magic = NILFS_TI_MAGIC;
175 	current->journal_info = ti;
176 	return 0;
177 }
178 
179 /**
180  * nilfs_transaction_begin - start indivisible file operations.
181  * @sb: super block
182  * @ti: nilfs_transaction_info
183  * @vacancy_check: flags for vacancy rate checks
184  *
185  * nilfs_transaction_begin() acquires a reader/writer semaphore, called
186  * the segment semaphore, to make a segment construction and write tasks
187  * exclusive.  The function is used with nilfs_transaction_commit() in pairs.
188  * The region enclosed by these two functions can be nested.  To avoid a
189  * deadlock, the semaphore is only acquired or released in the outermost call.
190  *
191  * This function allocates a nilfs_transaction_info struct to keep context
192  * information on it.  It is initialized and hooked onto the current task in
193  * the outermost call.  If a pre-allocated struct is given to @ti, it is used
194  * instead; otherwise a new struct is assigned from a slab.
195  *
196  * When @vacancy_check flag is set, this function will check the amount of
197  * free space, and will wait for the GC to reclaim disk space if low capacity.
198  *
199  * Return Value: On success, 0 is returned. On error, one of the following
200  * negative error code is returned.
201  *
202  * %-ENOMEM - Insufficient memory available.
203  *
204  * %-ENOSPC - No space left on device
205  */
206 int nilfs_transaction_begin(struct super_block *sb,
207 			    struct nilfs_transaction_info *ti,
208 			    int vacancy_check)
209 {
210 	struct the_nilfs *nilfs;
211 	int ret = nilfs_prepare_segment_lock(sb, ti);
212 	struct nilfs_transaction_info *trace_ti;
213 
214 	if (unlikely(ret < 0))
215 		return ret;
216 	if (ret > 0) {
217 		trace_ti = current->journal_info;
218 
219 		trace_nilfs2_transaction_transition(sb, trace_ti,
220 				    trace_ti->ti_count, trace_ti->ti_flags,
221 				    TRACE_NILFS2_TRANSACTION_BEGIN);
222 		return 0;
223 	}
224 
225 	sb_start_intwrite(sb);
226 
227 	nilfs = sb->s_fs_info;
228 	down_read(&nilfs->ns_segctor_sem);
229 	if (vacancy_check && nilfs_near_disk_full(nilfs)) {
230 		up_read(&nilfs->ns_segctor_sem);
231 		ret = -ENOSPC;
232 		goto failed;
233 	}
234 
235 	trace_ti = current->journal_info;
236 	trace_nilfs2_transaction_transition(sb, trace_ti, trace_ti->ti_count,
237 					    trace_ti->ti_flags,
238 					    TRACE_NILFS2_TRANSACTION_BEGIN);
239 	return 0;
240 
241  failed:
242 	ti = current->journal_info;
243 	current->journal_info = ti->ti_save;
244 	if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
245 		kmem_cache_free(nilfs_transaction_cachep, ti);
246 	sb_end_intwrite(sb);
247 	return ret;
248 }
249 
250 /**
251  * nilfs_transaction_commit - commit indivisible file operations.
252  * @sb: super block
253  *
254  * nilfs_transaction_commit() releases the read semaphore which is
255  * acquired by nilfs_transaction_begin(). This is only performed
256  * in outermost call of this function.  If a commit flag is set,
257  * nilfs_transaction_commit() sets a timer to start the segment
258  * constructor.  If a sync flag is set, it starts construction
259  * directly.
260  */
261 int nilfs_transaction_commit(struct super_block *sb)
262 {
263 	struct nilfs_transaction_info *ti = current->journal_info;
264 	struct the_nilfs *nilfs = sb->s_fs_info;
265 	int err = 0;
266 
267 	BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
268 	ti->ti_flags |= NILFS_TI_COMMIT;
269 	if (ti->ti_count > 0) {
270 		ti->ti_count--;
271 		trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
272 			    ti->ti_flags, TRACE_NILFS2_TRANSACTION_COMMIT);
273 		return 0;
274 	}
275 	if (nilfs->ns_writer) {
276 		struct nilfs_sc_info *sci = nilfs->ns_writer;
277 
278 		if (ti->ti_flags & NILFS_TI_COMMIT)
279 			nilfs_segctor_start_timer(sci);
280 		if (atomic_read(&nilfs->ns_ndirtyblks) > sci->sc_watermark)
281 			nilfs_segctor_do_flush(sci, 0);
282 	}
283 	up_read(&nilfs->ns_segctor_sem);
284 	trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
285 			    ti->ti_flags, TRACE_NILFS2_TRANSACTION_COMMIT);
286 
287 	current->journal_info = ti->ti_save;
288 
289 	if (ti->ti_flags & NILFS_TI_SYNC)
290 		err = nilfs_construct_segment(sb);
291 	if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
292 		kmem_cache_free(nilfs_transaction_cachep, ti);
293 	sb_end_intwrite(sb);
294 	return err;
295 }
296 
297 void nilfs_transaction_abort(struct super_block *sb)
298 {
299 	struct nilfs_transaction_info *ti = current->journal_info;
300 	struct the_nilfs *nilfs = sb->s_fs_info;
301 
302 	BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
303 	if (ti->ti_count > 0) {
304 		ti->ti_count--;
305 		trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
306 			    ti->ti_flags, TRACE_NILFS2_TRANSACTION_ABORT);
307 		return;
308 	}
309 	up_read(&nilfs->ns_segctor_sem);
310 
311 	trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
312 		    ti->ti_flags, TRACE_NILFS2_TRANSACTION_ABORT);
313 
314 	current->journal_info = ti->ti_save;
315 	if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
316 		kmem_cache_free(nilfs_transaction_cachep, ti);
317 	sb_end_intwrite(sb);
318 }
319 
320 void nilfs_relax_pressure_in_lock(struct super_block *sb)
321 {
322 	struct the_nilfs *nilfs = sb->s_fs_info;
323 	struct nilfs_sc_info *sci = nilfs->ns_writer;
324 
325 	if (!sci || !sci->sc_flush_request)
326 		return;
327 
328 	set_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags);
329 	up_read(&nilfs->ns_segctor_sem);
330 
331 	down_write(&nilfs->ns_segctor_sem);
332 	if (sci->sc_flush_request &&
333 	    test_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags)) {
334 		struct nilfs_transaction_info *ti = current->journal_info;
335 
336 		ti->ti_flags |= NILFS_TI_WRITER;
337 		nilfs_segctor_do_immediate_flush(sci);
338 		ti->ti_flags &= ~NILFS_TI_WRITER;
339 	}
340 	downgrade_write(&nilfs->ns_segctor_sem);
341 }
342 
343 static void nilfs_transaction_lock(struct super_block *sb,
344 				   struct nilfs_transaction_info *ti,
345 				   int gcflag)
346 {
347 	struct nilfs_transaction_info *cur_ti = current->journal_info;
348 	struct the_nilfs *nilfs = sb->s_fs_info;
349 	struct nilfs_sc_info *sci = nilfs->ns_writer;
350 
351 	WARN_ON(cur_ti);
352 	ti->ti_flags = NILFS_TI_WRITER;
353 	ti->ti_count = 0;
354 	ti->ti_save = cur_ti;
355 	ti->ti_magic = NILFS_TI_MAGIC;
356 	current->journal_info = ti;
357 
358 	for (;;) {
359 		trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
360 			    ti->ti_flags, TRACE_NILFS2_TRANSACTION_TRYLOCK);
361 
362 		down_write(&nilfs->ns_segctor_sem);
363 		if (!test_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags))
364 			break;
365 
366 		nilfs_segctor_do_immediate_flush(sci);
367 
368 		up_write(&nilfs->ns_segctor_sem);
369 		cond_resched();
370 	}
371 	if (gcflag)
372 		ti->ti_flags |= NILFS_TI_GC;
373 
374 	trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
375 			    ti->ti_flags, TRACE_NILFS2_TRANSACTION_LOCK);
376 }
377 
378 static void nilfs_transaction_unlock(struct super_block *sb)
379 {
380 	struct nilfs_transaction_info *ti = current->journal_info;
381 	struct the_nilfs *nilfs = sb->s_fs_info;
382 
383 	BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
384 	BUG_ON(ti->ti_count > 0);
385 
386 	up_write(&nilfs->ns_segctor_sem);
387 	current->journal_info = ti->ti_save;
388 
389 	trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
390 			    ti->ti_flags, TRACE_NILFS2_TRANSACTION_UNLOCK);
391 }
392 
393 static void *nilfs_segctor_map_segsum_entry(struct nilfs_sc_info *sci,
394 					    struct nilfs_segsum_pointer *ssp,
395 					    unsigned int bytes)
396 {
397 	struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
398 	unsigned int blocksize = sci->sc_super->s_blocksize;
399 	void *p;
400 
401 	if (unlikely(ssp->offset + bytes > blocksize)) {
402 		ssp->offset = 0;
403 		BUG_ON(NILFS_SEGBUF_BH_IS_LAST(ssp->bh,
404 					       &segbuf->sb_segsum_buffers));
405 		ssp->bh = NILFS_SEGBUF_NEXT_BH(ssp->bh);
406 	}
407 	p = ssp->bh->b_data + ssp->offset;
408 	ssp->offset += bytes;
409 	return p;
410 }
411 
412 /**
413  * nilfs_segctor_reset_segment_buffer - reset the current segment buffer
414  * @sci: nilfs_sc_info
415  */
416 static int nilfs_segctor_reset_segment_buffer(struct nilfs_sc_info *sci)
417 {
418 	struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
419 	struct buffer_head *sumbh;
420 	unsigned int sumbytes;
421 	unsigned int flags = 0;
422 	int err;
423 
424 	if (nilfs_doing_gc())
425 		flags = NILFS_SS_GC;
426 	err = nilfs_segbuf_reset(segbuf, flags, sci->sc_seg_ctime, sci->sc_cno);
427 	if (unlikely(err))
428 		return err;
429 
430 	sumbh = NILFS_SEGBUF_FIRST_BH(&segbuf->sb_segsum_buffers);
431 	sumbytes = segbuf->sb_sum.sumbytes;
432 	sci->sc_finfo_ptr.bh = sumbh;  sci->sc_finfo_ptr.offset = sumbytes;
433 	sci->sc_binfo_ptr.bh = sumbh;  sci->sc_binfo_ptr.offset = sumbytes;
434 	sci->sc_blk_cnt = sci->sc_datablk_cnt = 0;
435 	return 0;
436 }
437 
438 static int nilfs_segctor_feed_segment(struct nilfs_sc_info *sci)
439 {
440 	sci->sc_nblk_this_inc += sci->sc_curseg->sb_sum.nblocks;
441 	if (NILFS_SEGBUF_IS_LAST(sci->sc_curseg, &sci->sc_segbufs))
442 		return -E2BIG; /*
443 				* The current segment is filled up
444 				* (internal code)
445 				*/
446 	sci->sc_curseg = NILFS_NEXT_SEGBUF(sci->sc_curseg);
447 	return nilfs_segctor_reset_segment_buffer(sci);
448 }
449 
450 static int nilfs_segctor_add_super_root(struct nilfs_sc_info *sci)
451 {
452 	struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
453 	int err;
454 
455 	if (segbuf->sb_sum.nblocks >= segbuf->sb_rest_blocks) {
456 		err = nilfs_segctor_feed_segment(sci);
457 		if (err)
458 			return err;
459 		segbuf = sci->sc_curseg;
460 	}
461 	err = nilfs_segbuf_extend_payload(segbuf, &segbuf->sb_super_root);
462 	if (likely(!err))
463 		segbuf->sb_sum.flags |= NILFS_SS_SR;
464 	return err;
465 }
466 
467 /*
468  * Functions for making segment summary and payloads
469  */
470 static int nilfs_segctor_segsum_block_required(
471 	struct nilfs_sc_info *sci, const struct nilfs_segsum_pointer *ssp,
472 	unsigned int binfo_size)
473 {
474 	unsigned int blocksize = sci->sc_super->s_blocksize;
475 	/* Size of finfo and binfo is enough small against blocksize */
476 
477 	return ssp->offset + binfo_size +
478 		(!sci->sc_blk_cnt ? sizeof(struct nilfs_finfo) : 0) >
479 		blocksize;
480 }
481 
482 static void nilfs_segctor_begin_finfo(struct nilfs_sc_info *sci,
483 				      struct inode *inode)
484 {
485 	sci->sc_curseg->sb_sum.nfinfo++;
486 	sci->sc_binfo_ptr = sci->sc_finfo_ptr;
487 	nilfs_segctor_map_segsum_entry(
488 		sci, &sci->sc_binfo_ptr, sizeof(struct nilfs_finfo));
489 
490 	if (NILFS_I(inode)->i_root &&
491 	    !test_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags))
492 		set_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
493 	/* skip finfo */
494 }
495 
496 static void nilfs_segctor_end_finfo(struct nilfs_sc_info *sci,
497 				    struct inode *inode)
498 {
499 	struct nilfs_finfo *finfo;
500 	struct nilfs_inode_info *ii;
501 	struct nilfs_segment_buffer *segbuf;
502 	__u64 cno;
503 
504 	if (sci->sc_blk_cnt == 0)
505 		return;
506 
507 	ii = NILFS_I(inode);
508 
509 	if (test_bit(NILFS_I_GCINODE, &ii->i_state))
510 		cno = ii->i_cno;
511 	else if (NILFS_ROOT_METADATA_FILE(inode->i_ino))
512 		cno = 0;
513 	else
514 		cno = sci->sc_cno;
515 
516 	finfo = nilfs_segctor_map_segsum_entry(sci, &sci->sc_finfo_ptr,
517 						 sizeof(*finfo));
518 	finfo->fi_ino = cpu_to_le64(inode->i_ino);
519 	finfo->fi_nblocks = cpu_to_le32(sci->sc_blk_cnt);
520 	finfo->fi_ndatablk = cpu_to_le32(sci->sc_datablk_cnt);
521 	finfo->fi_cno = cpu_to_le64(cno);
522 
523 	segbuf = sci->sc_curseg;
524 	segbuf->sb_sum.sumbytes = sci->sc_binfo_ptr.offset +
525 		sci->sc_super->s_blocksize * (segbuf->sb_sum.nsumblk - 1);
526 	sci->sc_finfo_ptr = sci->sc_binfo_ptr;
527 	sci->sc_blk_cnt = sci->sc_datablk_cnt = 0;
528 }
529 
530 static int nilfs_segctor_add_file_block(struct nilfs_sc_info *sci,
531 					struct buffer_head *bh,
532 					struct inode *inode,
533 					unsigned int binfo_size)
534 {
535 	struct nilfs_segment_buffer *segbuf;
536 	int required, err = 0;
537 
538  retry:
539 	segbuf = sci->sc_curseg;
540 	required = nilfs_segctor_segsum_block_required(
541 		sci, &sci->sc_binfo_ptr, binfo_size);
542 	if (segbuf->sb_sum.nblocks + required + 1 > segbuf->sb_rest_blocks) {
543 		nilfs_segctor_end_finfo(sci, inode);
544 		err = nilfs_segctor_feed_segment(sci);
545 		if (err)
546 			return err;
547 		goto retry;
548 	}
549 	if (unlikely(required)) {
550 		err = nilfs_segbuf_extend_segsum(segbuf);
551 		if (unlikely(err))
552 			goto failed;
553 	}
554 	if (sci->sc_blk_cnt == 0)
555 		nilfs_segctor_begin_finfo(sci, inode);
556 
557 	nilfs_segctor_map_segsum_entry(sci, &sci->sc_binfo_ptr, binfo_size);
558 	/* Substitution to vblocknr is delayed until update_blocknr() */
559 	nilfs_segbuf_add_file_buffer(segbuf, bh);
560 	sci->sc_blk_cnt++;
561  failed:
562 	return err;
563 }
564 
565 /*
566  * Callback functions that enumerate, mark, and collect dirty blocks
567  */
568 static int nilfs_collect_file_data(struct nilfs_sc_info *sci,
569 				   struct buffer_head *bh, struct inode *inode)
570 {
571 	int err;
572 
573 	err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
574 	if (err < 0)
575 		return err;
576 
577 	err = nilfs_segctor_add_file_block(sci, bh, inode,
578 					   sizeof(struct nilfs_binfo_v));
579 	if (!err)
580 		sci->sc_datablk_cnt++;
581 	return err;
582 }
583 
584 static int nilfs_collect_file_node(struct nilfs_sc_info *sci,
585 				   struct buffer_head *bh,
586 				   struct inode *inode)
587 {
588 	return nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
589 }
590 
591 static int nilfs_collect_file_bmap(struct nilfs_sc_info *sci,
592 				   struct buffer_head *bh,
593 				   struct inode *inode)
594 {
595 	WARN_ON(!buffer_dirty(bh));
596 	return nilfs_segctor_add_file_block(sci, bh, inode, sizeof(__le64));
597 }
598 
599 static void nilfs_write_file_data_binfo(struct nilfs_sc_info *sci,
600 					struct nilfs_segsum_pointer *ssp,
601 					union nilfs_binfo *binfo)
602 {
603 	struct nilfs_binfo_v *binfo_v = nilfs_segctor_map_segsum_entry(
604 		sci, ssp, sizeof(*binfo_v));
605 	*binfo_v = binfo->bi_v;
606 }
607 
608 static void nilfs_write_file_node_binfo(struct nilfs_sc_info *sci,
609 					struct nilfs_segsum_pointer *ssp,
610 					union nilfs_binfo *binfo)
611 {
612 	__le64 *vblocknr = nilfs_segctor_map_segsum_entry(
613 		sci, ssp, sizeof(*vblocknr));
614 	*vblocknr = binfo->bi_v.bi_vblocknr;
615 }
616 
617 static const struct nilfs_sc_operations nilfs_sc_file_ops = {
618 	.collect_data = nilfs_collect_file_data,
619 	.collect_node = nilfs_collect_file_node,
620 	.collect_bmap = nilfs_collect_file_bmap,
621 	.write_data_binfo = nilfs_write_file_data_binfo,
622 	.write_node_binfo = nilfs_write_file_node_binfo,
623 };
624 
625 static int nilfs_collect_dat_data(struct nilfs_sc_info *sci,
626 				  struct buffer_head *bh, struct inode *inode)
627 {
628 	int err;
629 
630 	err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
631 	if (err < 0)
632 		return err;
633 
634 	err = nilfs_segctor_add_file_block(sci, bh, inode, sizeof(__le64));
635 	if (!err)
636 		sci->sc_datablk_cnt++;
637 	return err;
638 }
639 
640 static int nilfs_collect_dat_bmap(struct nilfs_sc_info *sci,
641 				  struct buffer_head *bh, struct inode *inode)
642 {
643 	WARN_ON(!buffer_dirty(bh));
644 	return nilfs_segctor_add_file_block(sci, bh, inode,
645 					    sizeof(struct nilfs_binfo_dat));
646 }
647 
648 static void nilfs_write_dat_data_binfo(struct nilfs_sc_info *sci,
649 				       struct nilfs_segsum_pointer *ssp,
650 				       union nilfs_binfo *binfo)
651 {
652 	__le64 *blkoff = nilfs_segctor_map_segsum_entry(sci, ssp,
653 							  sizeof(*blkoff));
654 	*blkoff = binfo->bi_dat.bi_blkoff;
655 }
656 
657 static void nilfs_write_dat_node_binfo(struct nilfs_sc_info *sci,
658 				       struct nilfs_segsum_pointer *ssp,
659 				       union nilfs_binfo *binfo)
660 {
661 	struct nilfs_binfo_dat *binfo_dat =
662 		nilfs_segctor_map_segsum_entry(sci, ssp, sizeof(*binfo_dat));
663 	*binfo_dat = binfo->bi_dat;
664 }
665 
666 static const struct nilfs_sc_operations nilfs_sc_dat_ops = {
667 	.collect_data = nilfs_collect_dat_data,
668 	.collect_node = nilfs_collect_file_node,
669 	.collect_bmap = nilfs_collect_dat_bmap,
670 	.write_data_binfo = nilfs_write_dat_data_binfo,
671 	.write_node_binfo = nilfs_write_dat_node_binfo,
672 };
673 
674 static const struct nilfs_sc_operations nilfs_sc_dsync_ops = {
675 	.collect_data = nilfs_collect_file_data,
676 	.collect_node = NULL,
677 	.collect_bmap = NULL,
678 	.write_data_binfo = nilfs_write_file_data_binfo,
679 	.write_node_binfo = NULL,
680 };
681 
682 static size_t nilfs_lookup_dirty_data_buffers(struct inode *inode,
683 					      struct list_head *listp,
684 					      size_t nlimit,
685 					      loff_t start, loff_t end)
686 {
687 	struct address_space *mapping = inode->i_mapping;
688 	struct pagevec pvec;
689 	pgoff_t index = 0, last = ULONG_MAX;
690 	size_t ndirties = 0;
691 	int i;
692 
693 	if (unlikely(start != 0 || end != LLONG_MAX)) {
694 		/*
695 		 * A valid range is given for sync-ing data pages. The
696 		 * range is rounded to per-page; extra dirty buffers
697 		 * may be included if blocksize < pagesize.
698 		 */
699 		index = start >> PAGE_SHIFT;
700 		last = end >> PAGE_SHIFT;
701 	}
702 	pagevec_init(&pvec);
703  repeat:
704 	if (unlikely(index > last) ||
705 	    !pagevec_lookup_range_tag(&pvec, mapping, &index, last,
706 				PAGECACHE_TAG_DIRTY))
707 		return ndirties;
708 
709 	for (i = 0; i < pagevec_count(&pvec); i++) {
710 		struct buffer_head *bh, *head;
711 		struct page *page = pvec.pages[i];
712 
713 		lock_page(page);
714 		if (!page_has_buffers(page))
715 			create_empty_buffers(page, i_blocksize(inode), 0);
716 		unlock_page(page);
717 
718 		bh = head = page_buffers(page);
719 		do {
720 			if (!buffer_dirty(bh) || buffer_async_write(bh))
721 				continue;
722 			get_bh(bh);
723 			list_add_tail(&bh->b_assoc_buffers, listp);
724 			ndirties++;
725 			if (unlikely(ndirties >= nlimit)) {
726 				pagevec_release(&pvec);
727 				cond_resched();
728 				return ndirties;
729 			}
730 		} while (bh = bh->b_this_page, bh != head);
731 	}
732 	pagevec_release(&pvec);
733 	cond_resched();
734 	goto repeat;
735 }
736 
737 static void nilfs_lookup_dirty_node_buffers(struct inode *inode,
738 					    struct list_head *listp)
739 {
740 	struct nilfs_inode_info *ii = NILFS_I(inode);
741 	struct address_space *mapping = &ii->i_btnode_cache;
742 	struct pagevec pvec;
743 	struct buffer_head *bh, *head;
744 	unsigned int i;
745 	pgoff_t index = 0;
746 
747 	pagevec_init(&pvec);
748 
749 	while (pagevec_lookup_tag(&pvec, mapping, &index,
750 					PAGECACHE_TAG_DIRTY)) {
751 		for (i = 0; i < pagevec_count(&pvec); i++) {
752 			bh = head = page_buffers(pvec.pages[i]);
753 			do {
754 				if (buffer_dirty(bh) &&
755 						!buffer_async_write(bh)) {
756 					get_bh(bh);
757 					list_add_tail(&bh->b_assoc_buffers,
758 						      listp);
759 				}
760 				bh = bh->b_this_page;
761 			} while (bh != head);
762 		}
763 		pagevec_release(&pvec);
764 		cond_resched();
765 	}
766 }
767 
768 static void nilfs_dispose_list(struct the_nilfs *nilfs,
769 			       struct list_head *head, int force)
770 {
771 	struct nilfs_inode_info *ii, *n;
772 	struct nilfs_inode_info *ivec[SC_N_INODEVEC], **pii;
773 	unsigned int nv = 0;
774 
775 	while (!list_empty(head)) {
776 		spin_lock(&nilfs->ns_inode_lock);
777 		list_for_each_entry_safe(ii, n, head, i_dirty) {
778 			list_del_init(&ii->i_dirty);
779 			if (force) {
780 				if (unlikely(ii->i_bh)) {
781 					brelse(ii->i_bh);
782 					ii->i_bh = NULL;
783 				}
784 			} else if (test_bit(NILFS_I_DIRTY, &ii->i_state)) {
785 				set_bit(NILFS_I_QUEUED, &ii->i_state);
786 				list_add_tail(&ii->i_dirty,
787 					      &nilfs->ns_dirty_files);
788 				continue;
789 			}
790 			ivec[nv++] = ii;
791 			if (nv == SC_N_INODEVEC)
792 				break;
793 		}
794 		spin_unlock(&nilfs->ns_inode_lock);
795 
796 		for (pii = ivec; nv > 0; pii++, nv--)
797 			iput(&(*pii)->vfs_inode);
798 	}
799 }
800 
801 static void nilfs_iput_work_func(struct work_struct *work)
802 {
803 	struct nilfs_sc_info *sci = container_of(work, struct nilfs_sc_info,
804 						 sc_iput_work);
805 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
806 
807 	nilfs_dispose_list(nilfs, &sci->sc_iput_queue, 0);
808 }
809 
810 static int nilfs_test_metadata_dirty(struct the_nilfs *nilfs,
811 				     struct nilfs_root *root)
812 {
813 	int ret = 0;
814 
815 	if (nilfs_mdt_fetch_dirty(root->ifile))
816 		ret++;
817 	if (nilfs_mdt_fetch_dirty(nilfs->ns_cpfile))
818 		ret++;
819 	if (nilfs_mdt_fetch_dirty(nilfs->ns_sufile))
820 		ret++;
821 	if ((ret || nilfs_doing_gc()) && nilfs_mdt_fetch_dirty(nilfs->ns_dat))
822 		ret++;
823 	return ret;
824 }
825 
826 static int nilfs_segctor_clean(struct nilfs_sc_info *sci)
827 {
828 	return list_empty(&sci->sc_dirty_files) &&
829 		!test_bit(NILFS_SC_DIRTY, &sci->sc_flags) &&
830 		sci->sc_nfreesegs == 0 &&
831 		(!nilfs_doing_gc() || list_empty(&sci->sc_gc_inodes));
832 }
833 
834 static int nilfs_segctor_confirm(struct nilfs_sc_info *sci)
835 {
836 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
837 	int ret = 0;
838 
839 	if (nilfs_test_metadata_dirty(nilfs, sci->sc_root))
840 		set_bit(NILFS_SC_DIRTY, &sci->sc_flags);
841 
842 	spin_lock(&nilfs->ns_inode_lock);
843 	if (list_empty(&nilfs->ns_dirty_files) && nilfs_segctor_clean(sci))
844 		ret++;
845 
846 	spin_unlock(&nilfs->ns_inode_lock);
847 	return ret;
848 }
849 
850 static void nilfs_segctor_clear_metadata_dirty(struct nilfs_sc_info *sci)
851 {
852 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
853 
854 	nilfs_mdt_clear_dirty(sci->sc_root->ifile);
855 	nilfs_mdt_clear_dirty(nilfs->ns_cpfile);
856 	nilfs_mdt_clear_dirty(nilfs->ns_sufile);
857 	nilfs_mdt_clear_dirty(nilfs->ns_dat);
858 }
859 
860 static int nilfs_segctor_create_checkpoint(struct nilfs_sc_info *sci)
861 {
862 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
863 	struct buffer_head *bh_cp;
864 	struct nilfs_checkpoint *raw_cp;
865 	int err;
866 
867 	/* XXX: this interface will be changed */
868 	err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, 1,
869 					  &raw_cp, &bh_cp);
870 	if (likely(!err)) {
871 		/*
872 		 * The following code is duplicated with cpfile.  But, it is
873 		 * needed to collect the checkpoint even if it was not newly
874 		 * created.
875 		 */
876 		mark_buffer_dirty(bh_cp);
877 		nilfs_mdt_mark_dirty(nilfs->ns_cpfile);
878 		nilfs_cpfile_put_checkpoint(
879 			nilfs->ns_cpfile, nilfs->ns_cno, bh_cp);
880 	} else
881 		WARN_ON(err == -EINVAL || err == -ENOENT);
882 
883 	return err;
884 }
885 
886 static int nilfs_segctor_fill_in_checkpoint(struct nilfs_sc_info *sci)
887 {
888 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
889 	struct buffer_head *bh_cp;
890 	struct nilfs_checkpoint *raw_cp;
891 	int err;
892 
893 	err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, 0,
894 					  &raw_cp, &bh_cp);
895 	if (unlikely(err)) {
896 		WARN_ON(err == -EINVAL || err == -ENOENT);
897 		goto failed_ibh;
898 	}
899 	raw_cp->cp_snapshot_list.ssl_next = 0;
900 	raw_cp->cp_snapshot_list.ssl_prev = 0;
901 	raw_cp->cp_inodes_count =
902 		cpu_to_le64(atomic64_read(&sci->sc_root->inodes_count));
903 	raw_cp->cp_blocks_count =
904 		cpu_to_le64(atomic64_read(&sci->sc_root->blocks_count));
905 	raw_cp->cp_nblk_inc =
906 		cpu_to_le64(sci->sc_nblk_inc + sci->sc_nblk_this_inc);
907 	raw_cp->cp_create = cpu_to_le64(sci->sc_seg_ctime);
908 	raw_cp->cp_cno = cpu_to_le64(nilfs->ns_cno);
909 
910 	if (test_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags))
911 		nilfs_checkpoint_clear_minor(raw_cp);
912 	else
913 		nilfs_checkpoint_set_minor(raw_cp);
914 
915 	nilfs_write_inode_common(sci->sc_root->ifile,
916 				 &raw_cp->cp_ifile_inode, 1);
917 	nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, bh_cp);
918 	return 0;
919 
920  failed_ibh:
921 	return err;
922 }
923 
924 static void nilfs_fill_in_file_bmap(struct inode *ifile,
925 				    struct nilfs_inode_info *ii)
926 
927 {
928 	struct buffer_head *ibh;
929 	struct nilfs_inode *raw_inode;
930 
931 	if (test_bit(NILFS_I_BMAP, &ii->i_state)) {
932 		ibh = ii->i_bh;
933 		BUG_ON(!ibh);
934 		raw_inode = nilfs_ifile_map_inode(ifile, ii->vfs_inode.i_ino,
935 						  ibh);
936 		nilfs_bmap_write(ii->i_bmap, raw_inode);
937 		nilfs_ifile_unmap_inode(ifile, ii->vfs_inode.i_ino, ibh);
938 	}
939 }
940 
941 static void nilfs_segctor_fill_in_file_bmap(struct nilfs_sc_info *sci)
942 {
943 	struct nilfs_inode_info *ii;
944 
945 	list_for_each_entry(ii, &sci->sc_dirty_files, i_dirty) {
946 		nilfs_fill_in_file_bmap(sci->sc_root->ifile, ii);
947 		set_bit(NILFS_I_COLLECTED, &ii->i_state);
948 	}
949 }
950 
951 static void nilfs_segctor_fill_in_super_root(struct nilfs_sc_info *sci,
952 					     struct the_nilfs *nilfs)
953 {
954 	struct buffer_head *bh_sr;
955 	struct nilfs_super_root *raw_sr;
956 	unsigned int isz, srsz;
957 
958 	bh_sr = NILFS_LAST_SEGBUF(&sci->sc_segbufs)->sb_super_root;
959 	raw_sr = (struct nilfs_super_root *)bh_sr->b_data;
960 	isz = nilfs->ns_inode_size;
961 	srsz = NILFS_SR_BYTES(isz);
962 
963 	raw_sr->sr_bytes = cpu_to_le16(srsz);
964 	raw_sr->sr_nongc_ctime
965 		= cpu_to_le64(nilfs_doing_gc() ?
966 			      nilfs->ns_nongc_ctime : sci->sc_seg_ctime);
967 	raw_sr->sr_flags = 0;
968 
969 	nilfs_write_inode_common(nilfs->ns_dat, (void *)raw_sr +
970 				 NILFS_SR_DAT_OFFSET(isz), 1);
971 	nilfs_write_inode_common(nilfs->ns_cpfile, (void *)raw_sr +
972 				 NILFS_SR_CPFILE_OFFSET(isz), 1);
973 	nilfs_write_inode_common(nilfs->ns_sufile, (void *)raw_sr +
974 				 NILFS_SR_SUFILE_OFFSET(isz), 1);
975 	memset((void *)raw_sr + srsz, 0, nilfs->ns_blocksize - srsz);
976 }
977 
978 static void nilfs_redirty_inodes(struct list_head *head)
979 {
980 	struct nilfs_inode_info *ii;
981 
982 	list_for_each_entry(ii, head, i_dirty) {
983 		if (test_bit(NILFS_I_COLLECTED, &ii->i_state))
984 			clear_bit(NILFS_I_COLLECTED, &ii->i_state);
985 	}
986 }
987 
988 static void nilfs_drop_collected_inodes(struct list_head *head)
989 {
990 	struct nilfs_inode_info *ii;
991 
992 	list_for_each_entry(ii, head, i_dirty) {
993 		if (!test_and_clear_bit(NILFS_I_COLLECTED, &ii->i_state))
994 			continue;
995 
996 		clear_bit(NILFS_I_INODE_SYNC, &ii->i_state);
997 		set_bit(NILFS_I_UPDATED, &ii->i_state);
998 	}
999 }
1000 
1001 static int nilfs_segctor_apply_buffers(struct nilfs_sc_info *sci,
1002 				       struct inode *inode,
1003 				       struct list_head *listp,
1004 				       int (*collect)(struct nilfs_sc_info *,
1005 						      struct buffer_head *,
1006 						      struct inode *))
1007 {
1008 	struct buffer_head *bh, *n;
1009 	int err = 0;
1010 
1011 	if (collect) {
1012 		list_for_each_entry_safe(bh, n, listp, b_assoc_buffers) {
1013 			list_del_init(&bh->b_assoc_buffers);
1014 			err = collect(sci, bh, inode);
1015 			brelse(bh);
1016 			if (unlikely(err))
1017 				goto dispose_buffers;
1018 		}
1019 		return 0;
1020 	}
1021 
1022  dispose_buffers:
1023 	while (!list_empty(listp)) {
1024 		bh = list_first_entry(listp, struct buffer_head,
1025 				      b_assoc_buffers);
1026 		list_del_init(&bh->b_assoc_buffers);
1027 		brelse(bh);
1028 	}
1029 	return err;
1030 }
1031 
1032 static size_t nilfs_segctor_buffer_rest(struct nilfs_sc_info *sci)
1033 {
1034 	/* Remaining number of blocks within segment buffer */
1035 	return sci->sc_segbuf_nblocks -
1036 		(sci->sc_nblk_this_inc + sci->sc_curseg->sb_sum.nblocks);
1037 }
1038 
1039 static int nilfs_segctor_scan_file(struct nilfs_sc_info *sci,
1040 				   struct inode *inode,
1041 				   const struct nilfs_sc_operations *sc_ops)
1042 {
1043 	LIST_HEAD(data_buffers);
1044 	LIST_HEAD(node_buffers);
1045 	int err;
1046 
1047 	if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
1048 		size_t n, rest = nilfs_segctor_buffer_rest(sci);
1049 
1050 		n = nilfs_lookup_dirty_data_buffers(
1051 			inode, &data_buffers, rest + 1, 0, LLONG_MAX);
1052 		if (n > rest) {
1053 			err = nilfs_segctor_apply_buffers(
1054 				sci, inode, &data_buffers,
1055 				sc_ops->collect_data);
1056 			BUG_ON(!err); /* always receive -E2BIG or true error */
1057 			goto break_or_fail;
1058 		}
1059 	}
1060 	nilfs_lookup_dirty_node_buffers(inode, &node_buffers);
1061 
1062 	if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
1063 		err = nilfs_segctor_apply_buffers(
1064 			sci, inode, &data_buffers, sc_ops->collect_data);
1065 		if (unlikely(err)) {
1066 			/* dispose node list */
1067 			nilfs_segctor_apply_buffers(
1068 				sci, inode, &node_buffers, NULL);
1069 			goto break_or_fail;
1070 		}
1071 		sci->sc_stage.flags |= NILFS_CF_NODE;
1072 	}
1073 	/* Collect node */
1074 	err = nilfs_segctor_apply_buffers(
1075 		sci, inode, &node_buffers, sc_ops->collect_node);
1076 	if (unlikely(err))
1077 		goto break_or_fail;
1078 
1079 	nilfs_bmap_lookup_dirty_buffers(NILFS_I(inode)->i_bmap, &node_buffers);
1080 	err = nilfs_segctor_apply_buffers(
1081 		sci, inode, &node_buffers, sc_ops->collect_bmap);
1082 	if (unlikely(err))
1083 		goto break_or_fail;
1084 
1085 	nilfs_segctor_end_finfo(sci, inode);
1086 	sci->sc_stage.flags &= ~NILFS_CF_NODE;
1087 
1088  break_or_fail:
1089 	return err;
1090 }
1091 
1092 static int nilfs_segctor_scan_file_dsync(struct nilfs_sc_info *sci,
1093 					 struct inode *inode)
1094 {
1095 	LIST_HEAD(data_buffers);
1096 	size_t n, rest = nilfs_segctor_buffer_rest(sci);
1097 	int err;
1098 
1099 	n = nilfs_lookup_dirty_data_buffers(inode, &data_buffers, rest + 1,
1100 					    sci->sc_dsync_start,
1101 					    sci->sc_dsync_end);
1102 
1103 	err = nilfs_segctor_apply_buffers(sci, inode, &data_buffers,
1104 					  nilfs_collect_file_data);
1105 	if (!err) {
1106 		nilfs_segctor_end_finfo(sci, inode);
1107 		BUG_ON(n > rest);
1108 		/* always receive -E2BIG or true error if n > rest */
1109 	}
1110 	return err;
1111 }
1112 
1113 static int nilfs_segctor_collect_blocks(struct nilfs_sc_info *sci, int mode)
1114 {
1115 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
1116 	struct list_head *head;
1117 	struct nilfs_inode_info *ii;
1118 	size_t ndone;
1119 	int err = 0;
1120 
1121 	switch (nilfs_sc_cstage_get(sci)) {
1122 	case NILFS_ST_INIT:
1123 		/* Pre-processes */
1124 		sci->sc_stage.flags = 0;
1125 
1126 		if (!test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags)) {
1127 			sci->sc_nblk_inc = 0;
1128 			sci->sc_curseg->sb_sum.flags = NILFS_SS_LOGBGN;
1129 			if (mode == SC_LSEG_DSYNC) {
1130 				nilfs_sc_cstage_set(sci, NILFS_ST_DSYNC);
1131 				goto dsync_mode;
1132 			}
1133 		}
1134 
1135 		sci->sc_stage.dirty_file_ptr = NULL;
1136 		sci->sc_stage.gc_inode_ptr = NULL;
1137 		if (mode == SC_FLUSH_DAT) {
1138 			nilfs_sc_cstage_set(sci, NILFS_ST_DAT);
1139 			goto dat_stage;
1140 		}
1141 		nilfs_sc_cstage_inc(sci);
1142 		fallthrough;
1143 	case NILFS_ST_GC:
1144 		if (nilfs_doing_gc()) {
1145 			head = &sci->sc_gc_inodes;
1146 			ii = list_prepare_entry(sci->sc_stage.gc_inode_ptr,
1147 						head, i_dirty);
1148 			list_for_each_entry_continue(ii, head, i_dirty) {
1149 				err = nilfs_segctor_scan_file(
1150 					sci, &ii->vfs_inode,
1151 					&nilfs_sc_file_ops);
1152 				if (unlikely(err)) {
1153 					sci->sc_stage.gc_inode_ptr = list_entry(
1154 						ii->i_dirty.prev,
1155 						struct nilfs_inode_info,
1156 						i_dirty);
1157 					goto break_or_fail;
1158 				}
1159 				set_bit(NILFS_I_COLLECTED, &ii->i_state);
1160 			}
1161 			sci->sc_stage.gc_inode_ptr = NULL;
1162 		}
1163 		nilfs_sc_cstage_inc(sci);
1164 		fallthrough;
1165 	case NILFS_ST_FILE:
1166 		head = &sci->sc_dirty_files;
1167 		ii = list_prepare_entry(sci->sc_stage.dirty_file_ptr, head,
1168 					i_dirty);
1169 		list_for_each_entry_continue(ii, head, i_dirty) {
1170 			clear_bit(NILFS_I_DIRTY, &ii->i_state);
1171 
1172 			err = nilfs_segctor_scan_file(sci, &ii->vfs_inode,
1173 						      &nilfs_sc_file_ops);
1174 			if (unlikely(err)) {
1175 				sci->sc_stage.dirty_file_ptr =
1176 					list_entry(ii->i_dirty.prev,
1177 						   struct nilfs_inode_info,
1178 						   i_dirty);
1179 				goto break_or_fail;
1180 			}
1181 			/* sci->sc_stage.dirty_file_ptr = NILFS_I(inode); */
1182 			/* XXX: required ? */
1183 		}
1184 		sci->sc_stage.dirty_file_ptr = NULL;
1185 		if (mode == SC_FLUSH_FILE) {
1186 			nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1187 			return 0;
1188 		}
1189 		nilfs_sc_cstage_inc(sci);
1190 		sci->sc_stage.flags |= NILFS_CF_IFILE_STARTED;
1191 		fallthrough;
1192 	case NILFS_ST_IFILE:
1193 		err = nilfs_segctor_scan_file(sci, sci->sc_root->ifile,
1194 					      &nilfs_sc_file_ops);
1195 		if (unlikely(err))
1196 			break;
1197 		nilfs_sc_cstage_inc(sci);
1198 		/* Creating a checkpoint */
1199 		err = nilfs_segctor_create_checkpoint(sci);
1200 		if (unlikely(err))
1201 			break;
1202 		fallthrough;
1203 	case NILFS_ST_CPFILE:
1204 		err = nilfs_segctor_scan_file(sci, nilfs->ns_cpfile,
1205 					      &nilfs_sc_file_ops);
1206 		if (unlikely(err))
1207 			break;
1208 		nilfs_sc_cstage_inc(sci);
1209 		fallthrough;
1210 	case NILFS_ST_SUFILE:
1211 		err = nilfs_sufile_freev(nilfs->ns_sufile, sci->sc_freesegs,
1212 					 sci->sc_nfreesegs, &ndone);
1213 		if (unlikely(err)) {
1214 			nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1215 						  sci->sc_freesegs, ndone,
1216 						  NULL);
1217 			break;
1218 		}
1219 		sci->sc_stage.flags |= NILFS_CF_SUFREED;
1220 
1221 		err = nilfs_segctor_scan_file(sci, nilfs->ns_sufile,
1222 					      &nilfs_sc_file_ops);
1223 		if (unlikely(err))
1224 			break;
1225 		nilfs_sc_cstage_inc(sci);
1226 		fallthrough;
1227 	case NILFS_ST_DAT:
1228  dat_stage:
1229 		err = nilfs_segctor_scan_file(sci, nilfs->ns_dat,
1230 					      &nilfs_sc_dat_ops);
1231 		if (unlikely(err))
1232 			break;
1233 		if (mode == SC_FLUSH_DAT) {
1234 			nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1235 			return 0;
1236 		}
1237 		nilfs_sc_cstage_inc(sci);
1238 		fallthrough;
1239 	case NILFS_ST_SR:
1240 		if (mode == SC_LSEG_SR) {
1241 			/* Appending a super root */
1242 			err = nilfs_segctor_add_super_root(sci);
1243 			if (unlikely(err))
1244 				break;
1245 		}
1246 		/* End of a logical segment */
1247 		sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
1248 		nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1249 		return 0;
1250 	case NILFS_ST_DSYNC:
1251  dsync_mode:
1252 		sci->sc_curseg->sb_sum.flags |= NILFS_SS_SYNDT;
1253 		ii = sci->sc_dsync_inode;
1254 		if (!test_bit(NILFS_I_BUSY, &ii->i_state))
1255 			break;
1256 
1257 		err = nilfs_segctor_scan_file_dsync(sci, &ii->vfs_inode);
1258 		if (unlikely(err))
1259 			break;
1260 		sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
1261 		nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1262 		return 0;
1263 	case NILFS_ST_DONE:
1264 		return 0;
1265 	default:
1266 		BUG();
1267 	}
1268 
1269  break_or_fail:
1270 	return err;
1271 }
1272 
1273 /**
1274  * nilfs_segctor_begin_construction - setup segment buffer to make a new log
1275  * @sci: nilfs_sc_info
1276  * @nilfs: nilfs object
1277  */
1278 static int nilfs_segctor_begin_construction(struct nilfs_sc_info *sci,
1279 					    struct the_nilfs *nilfs)
1280 {
1281 	struct nilfs_segment_buffer *segbuf, *prev;
1282 	__u64 nextnum;
1283 	int err, alloc = 0;
1284 
1285 	segbuf = nilfs_segbuf_new(sci->sc_super);
1286 	if (unlikely(!segbuf))
1287 		return -ENOMEM;
1288 
1289 	if (list_empty(&sci->sc_write_logs)) {
1290 		nilfs_segbuf_map(segbuf, nilfs->ns_segnum,
1291 				 nilfs->ns_pseg_offset, nilfs);
1292 		if (segbuf->sb_rest_blocks < NILFS_PSEG_MIN_BLOCKS) {
1293 			nilfs_shift_to_next_segment(nilfs);
1294 			nilfs_segbuf_map(segbuf, nilfs->ns_segnum, 0, nilfs);
1295 		}
1296 
1297 		segbuf->sb_sum.seg_seq = nilfs->ns_seg_seq;
1298 		nextnum = nilfs->ns_nextnum;
1299 
1300 		if (nilfs->ns_segnum == nilfs->ns_nextnum)
1301 			/* Start from the head of a new full segment */
1302 			alloc++;
1303 	} else {
1304 		/* Continue logs */
1305 		prev = NILFS_LAST_SEGBUF(&sci->sc_write_logs);
1306 		nilfs_segbuf_map_cont(segbuf, prev);
1307 		segbuf->sb_sum.seg_seq = prev->sb_sum.seg_seq;
1308 		nextnum = prev->sb_nextnum;
1309 
1310 		if (segbuf->sb_rest_blocks < NILFS_PSEG_MIN_BLOCKS) {
1311 			nilfs_segbuf_map(segbuf, prev->sb_nextnum, 0, nilfs);
1312 			segbuf->sb_sum.seg_seq++;
1313 			alloc++;
1314 		}
1315 	}
1316 
1317 	err = nilfs_sufile_mark_dirty(nilfs->ns_sufile, segbuf->sb_segnum);
1318 	if (err)
1319 		goto failed;
1320 
1321 	if (alloc) {
1322 		err = nilfs_sufile_alloc(nilfs->ns_sufile, &nextnum);
1323 		if (err)
1324 			goto failed;
1325 	}
1326 	nilfs_segbuf_set_next_segnum(segbuf, nextnum, nilfs);
1327 
1328 	BUG_ON(!list_empty(&sci->sc_segbufs));
1329 	list_add_tail(&segbuf->sb_list, &sci->sc_segbufs);
1330 	sci->sc_segbuf_nblocks = segbuf->sb_rest_blocks;
1331 	return 0;
1332 
1333  failed:
1334 	nilfs_segbuf_free(segbuf);
1335 	return err;
1336 }
1337 
1338 static int nilfs_segctor_extend_segments(struct nilfs_sc_info *sci,
1339 					 struct the_nilfs *nilfs, int nadd)
1340 {
1341 	struct nilfs_segment_buffer *segbuf, *prev;
1342 	struct inode *sufile = nilfs->ns_sufile;
1343 	__u64 nextnextnum;
1344 	LIST_HEAD(list);
1345 	int err, ret, i;
1346 
1347 	prev = NILFS_LAST_SEGBUF(&sci->sc_segbufs);
1348 	/*
1349 	 * Since the segment specified with nextnum might be allocated during
1350 	 * the previous construction, the buffer including its segusage may
1351 	 * not be dirty.  The following call ensures that the buffer is dirty
1352 	 * and will pin the buffer on memory until the sufile is written.
1353 	 */
1354 	err = nilfs_sufile_mark_dirty(sufile, prev->sb_nextnum);
1355 	if (unlikely(err))
1356 		return err;
1357 
1358 	for (i = 0; i < nadd; i++) {
1359 		/* extend segment info */
1360 		err = -ENOMEM;
1361 		segbuf = nilfs_segbuf_new(sci->sc_super);
1362 		if (unlikely(!segbuf))
1363 			goto failed;
1364 
1365 		/* map this buffer to region of segment on-disk */
1366 		nilfs_segbuf_map(segbuf, prev->sb_nextnum, 0, nilfs);
1367 		sci->sc_segbuf_nblocks += segbuf->sb_rest_blocks;
1368 
1369 		/* allocate the next next full segment */
1370 		err = nilfs_sufile_alloc(sufile, &nextnextnum);
1371 		if (unlikely(err))
1372 			goto failed_segbuf;
1373 
1374 		segbuf->sb_sum.seg_seq = prev->sb_sum.seg_seq + 1;
1375 		nilfs_segbuf_set_next_segnum(segbuf, nextnextnum, nilfs);
1376 
1377 		list_add_tail(&segbuf->sb_list, &list);
1378 		prev = segbuf;
1379 	}
1380 	list_splice_tail(&list, &sci->sc_segbufs);
1381 	return 0;
1382 
1383  failed_segbuf:
1384 	nilfs_segbuf_free(segbuf);
1385  failed:
1386 	list_for_each_entry(segbuf, &list, sb_list) {
1387 		ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1388 		WARN_ON(ret); /* never fails */
1389 	}
1390 	nilfs_destroy_logs(&list);
1391 	return err;
1392 }
1393 
1394 static void nilfs_free_incomplete_logs(struct list_head *logs,
1395 				       struct the_nilfs *nilfs)
1396 {
1397 	struct nilfs_segment_buffer *segbuf, *prev;
1398 	struct inode *sufile = nilfs->ns_sufile;
1399 	int ret;
1400 
1401 	segbuf = NILFS_FIRST_SEGBUF(logs);
1402 	if (nilfs->ns_nextnum != segbuf->sb_nextnum) {
1403 		ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1404 		WARN_ON(ret); /* never fails */
1405 	}
1406 	if (atomic_read(&segbuf->sb_err)) {
1407 		/* Case 1: The first segment failed */
1408 		if (segbuf->sb_pseg_start != segbuf->sb_fseg_start)
1409 			/*
1410 			 * Case 1a:  Partial segment appended into an existing
1411 			 * segment
1412 			 */
1413 			nilfs_terminate_segment(nilfs, segbuf->sb_fseg_start,
1414 						segbuf->sb_fseg_end);
1415 		else /* Case 1b:  New full segment */
1416 			set_nilfs_discontinued(nilfs);
1417 	}
1418 
1419 	prev = segbuf;
1420 	list_for_each_entry_continue(segbuf, logs, sb_list) {
1421 		if (prev->sb_nextnum != segbuf->sb_nextnum) {
1422 			ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1423 			WARN_ON(ret); /* never fails */
1424 		}
1425 		if (atomic_read(&segbuf->sb_err) &&
1426 		    segbuf->sb_segnum != nilfs->ns_nextnum)
1427 			/* Case 2: extended segment (!= next) failed */
1428 			nilfs_sufile_set_error(sufile, segbuf->sb_segnum);
1429 		prev = segbuf;
1430 	}
1431 }
1432 
1433 static void nilfs_segctor_update_segusage(struct nilfs_sc_info *sci,
1434 					  struct inode *sufile)
1435 {
1436 	struct nilfs_segment_buffer *segbuf;
1437 	unsigned long live_blocks;
1438 	int ret;
1439 
1440 	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1441 		live_blocks = segbuf->sb_sum.nblocks +
1442 			(segbuf->sb_pseg_start - segbuf->sb_fseg_start);
1443 		ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1444 						     live_blocks,
1445 						     sci->sc_seg_ctime);
1446 		WARN_ON(ret); /* always succeed because the segusage is dirty */
1447 	}
1448 }
1449 
1450 static void nilfs_cancel_segusage(struct list_head *logs, struct inode *sufile)
1451 {
1452 	struct nilfs_segment_buffer *segbuf;
1453 	int ret;
1454 
1455 	segbuf = NILFS_FIRST_SEGBUF(logs);
1456 	ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1457 					     segbuf->sb_pseg_start -
1458 					     segbuf->sb_fseg_start, 0);
1459 	WARN_ON(ret); /* always succeed because the segusage is dirty */
1460 
1461 	list_for_each_entry_continue(segbuf, logs, sb_list) {
1462 		ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1463 						     0, 0);
1464 		WARN_ON(ret); /* always succeed */
1465 	}
1466 }
1467 
1468 static void nilfs_segctor_truncate_segments(struct nilfs_sc_info *sci,
1469 					    struct nilfs_segment_buffer *last,
1470 					    struct inode *sufile)
1471 {
1472 	struct nilfs_segment_buffer *segbuf = last;
1473 	int ret;
1474 
1475 	list_for_each_entry_continue(segbuf, &sci->sc_segbufs, sb_list) {
1476 		sci->sc_segbuf_nblocks -= segbuf->sb_rest_blocks;
1477 		ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1478 		WARN_ON(ret);
1479 	}
1480 	nilfs_truncate_logs(&sci->sc_segbufs, last);
1481 }
1482 
1483 
1484 static int nilfs_segctor_collect(struct nilfs_sc_info *sci,
1485 				 struct the_nilfs *nilfs, int mode)
1486 {
1487 	struct nilfs_cstage prev_stage = sci->sc_stage;
1488 	int err, nadd = 1;
1489 
1490 	/* Collection retry loop */
1491 	for (;;) {
1492 		sci->sc_nblk_this_inc = 0;
1493 		sci->sc_curseg = NILFS_FIRST_SEGBUF(&sci->sc_segbufs);
1494 
1495 		err = nilfs_segctor_reset_segment_buffer(sci);
1496 		if (unlikely(err))
1497 			goto failed;
1498 
1499 		err = nilfs_segctor_collect_blocks(sci, mode);
1500 		sci->sc_nblk_this_inc += sci->sc_curseg->sb_sum.nblocks;
1501 		if (!err)
1502 			break;
1503 
1504 		if (unlikely(err != -E2BIG))
1505 			goto failed;
1506 
1507 		/* The current segment is filled up */
1508 		if (mode != SC_LSEG_SR ||
1509 		    nilfs_sc_cstage_get(sci) < NILFS_ST_CPFILE)
1510 			break;
1511 
1512 		nilfs_clear_logs(&sci->sc_segbufs);
1513 
1514 		if (sci->sc_stage.flags & NILFS_CF_SUFREED) {
1515 			err = nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1516 							sci->sc_freesegs,
1517 							sci->sc_nfreesegs,
1518 							NULL);
1519 			WARN_ON(err); /* do not happen */
1520 			sci->sc_stage.flags &= ~NILFS_CF_SUFREED;
1521 		}
1522 
1523 		err = nilfs_segctor_extend_segments(sci, nilfs, nadd);
1524 		if (unlikely(err))
1525 			return err;
1526 
1527 		nadd = min_t(int, nadd << 1, SC_MAX_SEGDELTA);
1528 		sci->sc_stage = prev_stage;
1529 	}
1530 	nilfs_segctor_truncate_segments(sci, sci->sc_curseg, nilfs->ns_sufile);
1531 	return 0;
1532 
1533  failed:
1534 	return err;
1535 }
1536 
1537 static void nilfs_list_replace_buffer(struct buffer_head *old_bh,
1538 				      struct buffer_head *new_bh)
1539 {
1540 	BUG_ON(!list_empty(&new_bh->b_assoc_buffers));
1541 
1542 	list_replace_init(&old_bh->b_assoc_buffers, &new_bh->b_assoc_buffers);
1543 	/* The caller must release old_bh */
1544 }
1545 
1546 static int
1547 nilfs_segctor_update_payload_blocknr(struct nilfs_sc_info *sci,
1548 				     struct nilfs_segment_buffer *segbuf,
1549 				     int mode)
1550 {
1551 	struct inode *inode = NULL;
1552 	sector_t blocknr;
1553 	unsigned long nfinfo = segbuf->sb_sum.nfinfo;
1554 	unsigned long nblocks = 0, ndatablk = 0;
1555 	const struct nilfs_sc_operations *sc_op = NULL;
1556 	struct nilfs_segsum_pointer ssp;
1557 	struct nilfs_finfo *finfo = NULL;
1558 	union nilfs_binfo binfo;
1559 	struct buffer_head *bh, *bh_org;
1560 	ino_t ino = 0;
1561 	int err = 0;
1562 
1563 	if (!nfinfo)
1564 		goto out;
1565 
1566 	blocknr = segbuf->sb_pseg_start + segbuf->sb_sum.nsumblk;
1567 	ssp.bh = NILFS_SEGBUF_FIRST_BH(&segbuf->sb_segsum_buffers);
1568 	ssp.offset = sizeof(struct nilfs_segment_summary);
1569 
1570 	list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
1571 		if (bh == segbuf->sb_super_root)
1572 			break;
1573 		if (!finfo) {
1574 			finfo =	nilfs_segctor_map_segsum_entry(
1575 				sci, &ssp, sizeof(*finfo));
1576 			ino = le64_to_cpu(finfo->fi_ino);
1577 			nblocks = le32_to_cpu(finfo->fi_nblocks);
1578 			ndatablk = le32_to_cpu(finfo->fi_ndatablk);
1579 
1580 			inode = bh->b_page->mapping->host;
1581 
1582 			if (mode == SC_LSEG_DSYNC)
1583 				sc_op = &nilfs_sc_dsync_ops;
1584 			else if (ino == NILFS_DAT_INO)
1585 				sc_op = &nilfs_sc_dat_ops;
1586 			else /* file blocks */
1587 				sc_op = &nilfs_sc_file_ops;
1588 		}
1589 		bh_org = bh;
1590 		get_bh(bh_org);
1591 		err = nilfs_bmap_assign(NILFS_I(inode)->i_bmap, &bh, blocknr,
1592 					&binfo);
1593 		if (bh != bh_org)
1594 			nilfs_list_replace_buffer(bh_org, bh);
1595 		brelse(bh_org);
1596 		if (unlikely(err))
1597 			goto failed_bmap;
1598 
1599 		if (ndatablk > 0)
1600 			sc_op->write_data_binfo(sci, &ssp, &binfo);
1601 		else
1602 			sc_op->write_node_binfo(sci, &ssp, &binfo);
1603 
1604 		blocknr++;
1605 		if (--nblocks == 0) {
1606 			finfo = NULL;
1607 			if (--nfinfo == 0)
1608 				break;
1609 		} else if (ndatablk > 0)
1610 			ndatablk--;
1611 	}
1612  out:
1613 	return 0;
1614 
1615  failed_bmap:
1616 	return err;
1617 }
1618 
1619 static int nilfs_segctor_assign(struct nilfs_sc_info *sci, int mode)
1620 {
1621 	struct nilfs_segment_buffer *segbuf;
1622 	int err;
1623 
1624 	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1625 		err = nilfs_segctor_update_payload_blocknr(sci, segbuf, mode);
1626 		if (unlikely(err))
1627 			return err;
1628 		nilfs_segbuf_fill_in_segsum(segbuf);
1629 	}
1630 	return 0;
1631 }
1632 
1633 static void nilfs_begin_page_io(struct page *page)
1634 {
1635 	if (!page || PageWriteback(page))
1636 		/*
1637 		 * For split b-tree node pages, this function may be called
1638 		 * twice.  We ignore the 2nd or later calls by this check.
1639 		 */
1640 		return;
1641 
1642 	lock_page(page);
1643 	clear_page_dirty_for_io(page);
1644 	set_page_writeback(page);
1645 	unlock_page(page);
1646 }
1647 
1648 static void nilfs_segctor_prepare_write(struct nilfs_sc_info *sci)
1649 {
1650 	struct nilfs_segment_buffer *segbuf;
1651 	struct page *bd_page = NULL, *fs_page = NULL;
1652 
1653 	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1654 		struct buffer_head *bh;
1655 
1656 		list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1657 				    b_assoc_buffers) {
1658 			if (bh->b_page != bd_page) {
1659 				if (bd_page) {
1660 					lock_page(bd_page);
1661 					clear_page_dirty_for_io(bd_page);
1662 					set_page_writeback(bd_page);
1663 					unlock_page(bd_page);
1664 				}
1665 				bd_page = bh->b_page;
1666 			}
1667 		}
1668 
1669 		list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1670 				    b_assoc_buffers) {
1671 			set_buffer_async_write(bh);
1672 			if (bh == segbuf->sb_super_root) {
1673 				if (bh->b_page != bd_page) {
1674 					lock_page(bd_page);
1675 					clear_page_dirty_for_io(bd_page);
1676 					set_page_writeback(bd_page);
1677 					unlock_page(bd_page);
1678 					bd_page = bh->b_page;
1679 				}
1680 				break;
1681 			}
1682 			if (bh->b_page != fs_page) {
1683 				nilfs_begin_page_io(fs_page);
1684 				fs_page = bh->b_page;
1685 			}
1686 		}
1687 	}
1688 	if (bd_page) {
1689 		lock_page(bd_page);
1690 		clear_page_dirty_for_io(bd_page);
1691 		set_page_writeback(bd_page);
1692 		unlock_page(bd_page);
1693 	}
1694 	nilfs_begin_page_io(fs_page);
1695 }
1696 
1697 static int nilfs_segctor_write(struct nilfs_sc_info *sci,
1698 			       struct the_nilfs *nilfs)
1699 {
1700 	int ret;
1701 
1702 	ret = nilfs_write_logs(&sci->sc_segbufs, nilfs);
1703 	list_splice_tail_init(&sci->sc_segbufs, &sci->sc_write_logs);
1704 	return ret;
1705 }
1706 
1707 static void nilfs_end_page_io(struct page *page, int err)
1708 {
1709 	if (!page)
1710 		return;
1711 
1712 	if (buffer_nilfs_node(page_buffers(page)) && !PageWriteback(page)) {
1713 		/*
1714 		 * For b-tree node pages, this function may be called twice
1715 		 * or more because they might be split in a segment.
1716 		 */
1717 		if (PageDirty(page)) {
1718 			/*
1719 			 * For pages holding split b-tree node buffers, dirty
1720 			 * flag on the buffers may be cleared discretely.
1721 			 * In that case, the page is once redirtied for
1722 			 * remaining buffers, and it must be cancelled if
1723 			 * all the buffers get cleaned later.
1724 			 */
1725 			lock_page(page);
1726 			if (nilfs_page_buffers_clean(page))
1727 				__nilfs_clear_page_dirty(page);
1728 			unlock_page(page);
1729 		}
1730 		return;
1731 	}
1732 
1733 	if (!err) {
1734 		if (!nilfs_page_buffers_clean(page))
1735 			__set_page_dirty_nobuffers(page);
1736 		ClearPageError(page);
1737 	} else {
1738 		__set_page_dirty_nobuffers(page);
1739 		SetPageError(page);
1740 	}
1741 
1742 	end_page_writeback(page);
1743 }
1744 
1745 static void nilfs_abort_logs(struct list_head *logs, int err)
1746 {
1747 	struct nilfs_segment_buffer *segbuf;
1748 	struct page *bd_page = NULL, *fs_page = NULL;
1749 	struct buffer_head *bh;
1750 
1751 	if (list_empty(logs))
1752 		return;
1753 
1754 	list_for_each_entry(segbuf, logs, sb_list) {
1755 		list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1756 				    b_assoc_buffers) {
1757 			if (bh->b_page != bd_page) {
1758 				if (bd_page)
1759 					end_page_writeback(bd_page);
1760 				bd_page = bh->b_page;
1761 			}
1762 		}
1763 
1764 		list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1765 				    b_assoc_buffers) {
1766 			clear_buffer_async_write(bh);
1767 			if (bh == segbuf->sb_super_root) {
1768 				if (bh->b_page != bd_page) {
1769 					end_page_writeback(bd_page);
1770 					bd_page = bh->b_page;
1771 				}
1772 				break;
1773 			}
1774 			if (bh->b_page != fs_page) {
1775 				nilfs_end_page_io(fs_page, err);
1776 				fs_page = bh->b_page;
1777 			}
1778 		}
1779 	}
1780 	if (bd_page)
1781 		end_page_writeback(bd_page);
1782 
1783 	nilfs_end_page_io(fs_page, err);
1784 }
1785 
1786 static void nilfs_segctor_abort_construction(struct nilfs_sc_info *sci,
1787 					     struct the_nilfs *nilfs, int err)
1788 {
1789 	LIST_HEAD(logs);
1790 	int ret;
1791 
1792 	list_splice_tail_init(&sci->sc_write_logs, &logs);
1793 	ret = nilfs_wait_on_logs(&logs);
1794 	nilfs_abort_logs(&logs, ret ? : err);
1795 
1796 	list_splice_tail_init(&sci->sc_segbufs, &logs);
1797 	nilfs_cancel_segusage(&logs, nilfs->ns_sufile);
1798 	nilfs_free_incomplete_logs(&logs, nilfs);
1799 
1800 	if (sci->sc_stage.flags & NILFS_CF_SUFREED) {
1801 		ret = nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1802 						sci->sc_freesegs,
1803 						sci->sc_nfreesegs,
1804 						NULL);
1805 		WARN_ON(ret); /* do not happen */
1806 	}
1807 
1808 	nilfs_destroy_logs(&logs);
1809 }
1810 
1811 static void nilfs_set_next_segment(struct the_nilfs *nilfs,
1812 				   struct nilfs_segment_buffer *segbuf)
1813 {
1814 	nilfs->ns_segnum = segbuf->sb_segnum;
1815 	nilfs->ns_nextnum = segbuf->sb_nextnum;
1816 	nilfs->ns_pseg_offset = segbuf->sb_pseg_start - segbuf->sb_fseg_start
1817 		+ segbuf->sb_sum.nblocks;
1818 	nilfs->ns_seg_seq = segbuf->sb_sum.seg_seq;
1819 	nilfs->ns_ctime = segbuf->sb_sum.ctime;
1820 }
1821 
1822 static void nilfs_segctor_complete_write(struct nilfs_sc_info *sci)
1823 {
1824 	struct nilfs_segment_buffer *segbuf;
1825 	struct page *bd_page = NULL, *fs_page = NULL;
1826 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
1827 	int update_sr = false;
1828 
1829 	list_for_each_entry(segbuf, &sci->sc_write_logs, sb_list) {
1830 		struct buffer_head *bh;
1831 
1832 		list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1833 				    b_assoc_buffers) {
1834 			set_buffer_uptodate(bh);
1835 			clear_buffer_dirty(bh);
1836 			if (bh->b_page != bd_page) {
1837 				if (bd_page)
1838 					end_page_writeback(bd_page);
1839 				bd_page = bh->b_page;
1840 			}
1841 		}
1842 		/*
1843 		 * We assume that the buffers which belong to the same page
1844 		 * continue over the buffer list.
1845 		 * Under this assumption, the last BHs of pages is
1846 		 * identifiable by the discontinuity of bh->b_page
1847 		 * (page != fs_page).
1848 		 *
1849 		 * For B-tree node blocks, however, this assumption is not
1850 		 * guaranteed.  The cleanup code of B-tree node pages needs
1851 		 * special care.
1852 		 */
1853 		list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1854 				    b_assoc_buffers) {
1855 			const unsigned long set_bits = BIT(BH_Uptodate);
1856 			const unsigned long clear_bits =
1857 				(BIT(BH_Dirty) | BIT(BH_Async_Write) |
1858 				 BIT(BH_Delay) | BIT(BH_NILFS_Volatile) |
1859 				 BIT(BH_NILFS_Redirected));
1860 
1861 			set_mask_bits(&bh->b_state, clear_bits, set_bits);
1862 			if (bh == segbuf->sb_super_root) {
1863 				if (bh->b_page != bd_page) {
1864 					end_page_writeback(bd_page);
1865 					bd_page = bh->b_page;
1866 				}
1867 				update_sr = true;
1868 				break;
1869 			}
1870 			if (bh->b_page != fs_page) {
1871 				nilfs_end_page_io(fs_page, 0);
1872 				fs_page = bh->b_page;
1873 			}
1874 		}
1875 
1876 		if (!nilfs_segbuf_simplex(segbuf)) {
1877 			if (segbuf->sb_sum.flags & NILFS_SS_LOGBGN) {
1878 				set_bit(NILFS_SC_UNCLOSED, &sci->sc_flags);
1879 				sci->sc_lseg_stime = jiffies;
1880 			}
1881 			if (segbuf->sb_sum.flags & NILFS_SS_LOGEND)
1882 				clear_bit(NILFS_SC_UNCLOSED, &sci->sc_flags);
1883 		}
1884 	}
1885 	/*
1886 	 * Since pages may continue over multiple segment buffers,
1887 	 * end of the last page must be checked outside of the loop.
1888 	 */
1889 	if (bd_page)
1890 		end_page_writeback(bd_page);
1891 
1892 	nilfs_end_page_io(fs_page, 0);
1893 
1894 	nilfs_drop_collected_inodes(&sci->sc_dirty_files);
1895 
1896 	if (nilfs_doing_gc())
1897 		nilfs_drop_collected_inodes(&sci->sc_gc_inodes);
1898 	else
1899 		nilfs->ns_nongc_ctime = sci->sc_seg_ctime;
1900 
1901 	sci->sc_nblk_inc += sci->sc_nblk_this_inc;
1902 
1903 	segbuf = NILFS_LAST_SEGBUF(&sci->sc_write_logs);
1904 	nilfs_set_next_segment(nilfs, segbuf);
1905 
1906 	if (update_sr) {
1907 		nilfs->ns_flushed_device = 0;
1908 		nilfs_set_last_segment(nilfs, segbuf->sb_pseg_start,
1909 				       segbuf->sb_sum.seg_seq, nilfs->ns_cno++);
1910 
1911 		clear_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
1912 		clear_bit(NILFS_SC_DIRTY, &sci->sc_flags);
1913 		set_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags);
1914 		nilfs_segctor_clear_metadata_dirty(sci);
1915 	} else
1916 		clear_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags);
1917 }
1918 
1919 static int nilfs_segctor_wait(struct nilfs_sc_info *sci)
1920 {
1921 	int ret;
1922 
1923 	ret = nilfs_wait_on_logs(&sci->sc_write_logs);
1924 	if (!ret) {
1925 		nilfs_segctor_complete_write(sci);
1926 		nilfs_destroy_logs(&sci->sc_write_logs);
1927 	}
1928 	return ret;
1929 }
1930 
1931 static int nilfs_segctor_collect_dirty_files(struct nilfs_sc_info *sci,
1932 					     struct the_nilfs *nilfs)
1933 {
1934 	struct nilfs_inode_info *ii, *n;
1935 	struct inode *ifile = sci->sc_root->ifile;
1936 
1937 	spin_lock(&nilfs->ns_inode_lock);
1938  retry:
1939 	list_for_each_entry_safe(ii, n, &nilfs->ns_dirty_files, i_dirty) {
1940 		if (!ii->i_bh) {
1941 			struct buffer_head *ibh;
1942 			int err;
1943 
1944 			spin_unlock(&nilfs->ns_inode_lock);
1945 			err = nilfs_ifile_get_inode_block(
1946 				ifile, ii->vfs_inode.i_ino, &ibh);
1947 			if (unlikely(err)) {
1948 				nilfs_warn(sci->sc_super,
1949 					   "log writer: error %d getting inode block (ino=%lu)",
1950 					   err, ii->vfs_inode.i_ino);
1951 				return err;
1952 			}
1953 			spin_lock(&nilfs->ns_inode_lock);
1954 			if (likely(!ii->i_bh))
1955 				ii->i_bh = ibh;
1956 			else
1957 				brelse(ibh);
1958 			goto retry;
1959 		}
1960 
1961 		// Always redirty the buffer to avoid race condition
1962 		mark_buffer_dirty(ii->i_bh);
1963 		nilfs_mdt_mark_dirty(ifile);
1964 
1965 		clear_bit(NILFS_I_QUEUED, &ii->i_state);
1966 		set_bit(NILFS_I_BUSY, &ii->i_state);
1967 		list_move_tail(&ii->i_dirty, &sci->sc_dirty_files);
1968 	}
1969 	spin_unlock(&nilfs->ns_inode_lock);
1970 
1971 	return 0;
1972 }
1973 
1974 static void nilfs_segctor_drop_written_files(struct nilfs_sc_info *sci,
1975 					     struct the_nilfs *nilfs)
1976 {
1977 	struct nilfs_inode_info *ii, *n;
1978 	int during_mount = !(sci->sc_super->s_flags & SB_ACTIVE);
1979 	int defer_iput = false;
1980 
1981 	spin_lock(&nilfs->ns_inode_lock);
1982 	list_for_each_entry_safe(ii, n, &sci->sc_dirty_files, i_dirty) {
1983 		if (!test_and_clear_bit(NILFS_I_UPDATED, &ii->i_state) ||
1984 		    test_bit(NILFS_I_DIRTY, &ii->i_state))
1985 			continue;
1986 
1987 		clear_bit(NILFS_I_BUSY, &ii->i_state);
1988 		brelse(ii->i_bh);
1989 		ii->i_bh = NULL;
1990 		list_del_init(&ii->i_dirty);
1991 		if (!ii->vfs_inode.i_nlink || during_mount) {
1992 			/*
1993 			 * Defer calling iput() to avoid deadlocks if
1994 			 * i_nlink == 0 or mount is not yet finished.
1995 			 */
1996 			list_add_tail(&ii->i_dirty, &sci->sc_iput_queue);
1997 			defer_iput = true;
1998 		} else {
1999 			spin_unlock(&nilfs->ns_inode_lock);
2000 			iput(&ii->vfs_inode);
2001 			spin_lock(&nilfs->ns_inode_lock);
2002 		}
2003 	}
2004 	spin_unlock(&nilfs->ns_inode_lock);
2005 
2006 	if (defer_iput)
2007 		schedule_work(&sci->sc_iput_work);
2008 }
2009 
2010 /*
2011  * Main procedure of segment constructor
2012  */
2013 static int nilfs_segctor_do_construct(struct nilfs_sc_info *sci, int mode)
2014 {
2015 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2016 	int err;
2017 
2018 	nilfs_sc_cstage_set(sci, NILFS_ST_INIT);
2019 	sci->sc_cno = nilfs->ns_cno;
2020 
2021 	err = nilfs_segctor_collect_dirty_files(sci, nilfs);
2022 	if (unlikely(err))
2023 		goto out;
2024 
2025 	if (nilfs_test_metadata_dirty(nilfs, sci->sc_root))
2026 		set_bit(NILFS_SC_DIRTY, &sci->sc_flags);
2027 
2028 	if (nilfs_segctor_clean(sci))
2029 		goto out;
2030 
2031 	do {
2032 		sci->sc_stage.flags &= ~NILFS_CF_HISTORY_MASK;
2033 
2034 		err = nilfs_segctor_begin_construction(sci, nilfs);
2035 		if (unlikely(err))
2036 			goto out;
2037 
2038 		/* Update time stamp */
2039 		sci->sc_seg_ctime = ktime_get_real_seconds();
2040 
2041 		err = nilfs_segctor_collect(sci, nilfs, mode);
2042 		if (unlikely(err))
2043 			goto failed;
2044 
2045 		/* Avoid empty segment */
2046 		if (nilfs_sc_cstage_get(sci) == NILFS_ST_DONE &&
2047 		    nilfs_segbuf_empty(sci->sc_curseg)) {
2048 			nilfs_segctor_abort_construction(sci, nilfs, 1);
2049 			goto out;
2050 		}
2051 
2052 		err = nilfs_segctor_assign(sci, mode);
2053 		if (unlikely(err))
2054 			goto failed;
2055 
2056 		if (sci->sc_stage.flags & NILFS_CF_IFILE_STARTED)
2057 			nilfs_segctor_fill_in_file_bmap(sci);
2058 
2059 		if (mode == SC_LSEG_SR &&
2060 		    nilfs_sc_cstage_get(sci) >= NILFS_ST_CPFILE) {
2061 			err = nilfs_segctor_fill_in_checkpoint(sci);
2062 			if (unlikely(err))
2063 				goto failed_to_write;
2064 
2065 			nilfs_segctor_fill_in_super_root(sci, nilfs);
2066 		}
2067 		nilfs_segctor_update_segusage(sci, nilfs->ns_sufile);
2068 
2069 		/* Write partial segments */
2070 		nilfs_segctor_prepare_write(sci);
2071 
2072 		nilfs_add_checksums_on_logs(&sci->sc_segbufs,
2073 					    nilfs->ns_crc_seed);
2074 
2075 		err = nilfs_segctor_write(sci, nilfs);
2076 		if (unlikely(err))
2077 			goto failed_to_write;
2078 
2079 		if (nilfs_sc_cstage_get(sci) == NILFS_ST_DONE ||
2080 		    nilfs->ns_blocksize_bits != PAGE_SHIFT) {
2081 			/*
2082 			 * At this point, we avoid double buffering
2083 			 * for blocksize < pagesize because page dirty
2084 			 * flag is turned off during write and dirty
2085 			 * buffers are not properly collected for
2086 			 * pages crossing over segments.
2087 			 */
2088 			err = nilfs_segctor_wait(sci);
2089 			if (err)
2090 				goto failed_to_write;
2091 		}
2092 	} while (nilfs_sc_cstage_get(sci) != NILFS_ST_DONE);
2093 
2094  out:
2095 	nilfs_segctor_drop_written_files(sci, nilfs);
2096 	return err;
2097 
2098  failed_to_write:
2099 	if (sci->sc_stage.flags & NILFS_CF_IFILE_STARTED)
2100 		nilfs_redirty_inodes(&sci->sc_dirty_files);
2101 
2102  failed:
2103 	if (nilfs_doing_gc())
2104 		nilfs_redirty_inodes(&sci->sc_gc_inodes);
2105 	nilfs_segctor_abort_construction(sci, nilfs, err);
2106 	goto out;
2107 }
2108 
2109 /**
2110  * nilfs_segctor_start_timer - set timer of background write
2111  * @sci: nilfs_sc_info
2112  *
2113  * If the timer has already been set, it ignores the new request.
2114  * This function MUST be called within a section locking the segment
2115  * semaphore.
2116  */
2117 static void nilfs_segctor_start_timer(struct nilfs_sc_info *sci)
2118 {
2119 	spin_lock(&sci->sc_state_lock);
2120 	if (!(sci->sc_state & NILFS_SEGCTOR_COMMIT)) {
2121 		sci->sc_timer.expires = jiffies + sci->sc_interval;
2122 		add_timer(&sci->sc_timer);
2123 		sci->sc_state |= NILFS_SEGCTOR_COMMIT;
2124 	}
2125 	spin_unlock(&sci->sc_state_lock);
2126 }
2127 
2128 static void nilfs_segctor_do_flush(struct nilfs_sc_info *sci, int bn)
2129 {
2130 	spin_lock(&sci->sc_state_lock);
2131 	if (!(sci->sc_flush_request & BIT(bn))) {
2132 		unsigned long prev_req = sci->sc_flush_request;
2133 
2134 		sci->sc_flush_request |= BIT(bn);
2135 		if (!prev_req)
2136 			wake_up(&sci->sc_wait_daemon);
2137 	}
2138 	spin_unlock(&sci->sc_state_lock);
2139 }
2140 
2141 /**
2142  * nilfs_flush_segment - trigger a segment construction for resource control
2143  * @sb: super block
2144  * @ino: inode number of the file to be flushed out.
2145  */
2146 void nilfs_flush_segment(struct super_block *sb, ino_t ino)
2147 {
2148 	struct the_nilfs *nilfs = sb->s_fs_info;
2149 	struct nilfs_sc_info *sci = nilfs->ns_writer;
2150 
2151 	if (!sci || nilfs_doing_construction())
2152 		return;
2153 	nilfs_segctor_do_flush(sci, NILFS_MDT_INODE(sb, ino) ? ino : 0);
2154 					/* assign bit 0 to data files */
2155 }
2156 
2157 struct nilfs_segctor_wait_request {
2158 	wait_queue_entry_t	wq;
2159 	__u32		seq;
2160 	int		err;
2161 	atomic_t	done;
2162 };
2163 
2164 static int nilfs_segctor_sync(struct nilfs_sc_info *sci)
2165 {
2166 	struct nilfs_segctor_wait_request wait_req;
2167 	int err = 0;
2168 
2169 	spin_lock(&sci->sc_state_lock);
2170 	init_wait(&wait_req.wq);
2171 	wait_req.err = 0;
2172 	atomic_set(&wait_req.done, 0);
2173 	wait_req.seq = ++sci->sc_seq_request;
2174 	spin_unlock(&sci->sc_state_lock);
2175 
2176 	init_waitqueue_entry(&wait_req.wq, current);
2177 	add_wait_queue(&sci->sc_wait_request, &wait_req.wq);
2178 	set_current_state(TASK_INTERRUPTIBLE);
2179 	wake_up(&sci->sc_wait_daemon);
2180 
2181 	for (;;) {
2182 		if (atomic_read(&wait_req.done)) {
2183 			err = wait_req.err;
2184 			break;
2185 		}
2186 		if (!signal_pending(current)) {
2187 			schedule();
2188 			continue;
2189 		}
2190 		err = -ERESTARTSYS;
2191 		break;
2192 	}
2193 	finish_wait(&sci->sc_wait_request, &wait_req.wq);
2194 	return err;
2195 }
2196 
2197 static void nilfs_segctor_wakeup(struct nilfs_sc_info *sci, int err)
2198 {
2199 	struct nilfs_segctor_wait_request *wrq, *n;
2200 	unsigned long flags;
2201 
2202 	spin_lock_irqsave(&sci->sc_wait_request.lock, flags);
2203 	list_for_each_entry_safe(wrq, n, &sci->sc_wait_request.head, wq.entry) {
2204 		if (!atomic_read(&wrq->done) &&
2205 		    nilfs_cnt32_ge(sci->sc_seq_done, wrq->seq)) {
2206 			wrq->err = err;
2207 			atomic_set(&wrq->done, 1);
2208 		}
2209 		if (atomic_read(&wrq->done)) {
2210 			wrq->wq.func(&wrq->wq,
2211 				     TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
2212 				     0, NULL);
2213 		}
2214 	}
2215 	spin_unlock_irqrestore(&sci->sc_wait_request.lock, flags);
2216 }
2217 
2218 /**
2219  * nilfs_construct_segment - construct a logical segment
2220  * @sb: super block
2221  *
2222  * Return Value: On success, 0 is retured. On errors, one of the following
2223  * negative error code is returned.
2224  *
2225  * %-EROFS - Read only filesystem.
2226  *
2227  * %-EIO - I/O error
2228  *
2229  * %-ENOSPC - No space left on device (only in a panic state).
2230  *
2231  * %-ERESTARTSYS - Interrupted.
2232  *
2233  * %-ENOMEM - Insufficient memory available.
2234  */
2235 int nilfs_construct_segment(struct super_block *sb)
2236 {
2237 	struct the_nilfs *nilfs = sb->s_fs_info;
2238 	struct nilfs_sc_info *sci = nilfs->ns_writer;
2239 	struct nilfs_transaction_info *ti;
2240 	int err;
2241 
2242 	if (!sci)
2243 		return -EROFS;
2244 
2245 	/* A call inside transactions causes a deadlock. */
2246 	BUG_ON((ti = current->journal_info) && ti->ti_magic == NILFS_TI_MAGIC);
2247 
2248 	err = nilfs_segctor_sync(sci);
2249 	return err;
2250 }
2251 
2252 /**
2253  * nilfs_construct_dsync_segment - construct a data-only logical segment
2254  * @sb: super block
2255  * @inode: inode whose data blocks should be written out
2256  * @start: start byte offset
2257  * @end: end byte offset (inclusive)
2258  *
2259  * Return Value: On success, 0 is retured. On errors, one of the following
2260  * negative error code is returned.
2261  *
2262  * %-EROFS - Read only filesystem.
2263  *
2264  * %-EIO - I/O error
2265  *
2266  * %-ENOSPC - No space left on device (only in a panic state).
2267  *
2268  * %-ERESTARTSYS - Interrupted.
2269  *
2270  * %-ENOMEM - Insufficient memory available.
2271  */
2272 int nilfs_construct_dsync_segment(struct super_block *sb, struct inode *inode,
2273 				  loff_t start, loff_t end)
2274 {
2275 	struct the_nilfs *nilfs = sb->s_fs_info;
2276 	struct nilfs_sc_info *sci = nilfs->ns_writer;
2277 	struct nilfs_inode_info *ii;
2278 	struct nilfs_transaction_info ti;
2279 	int err = 0;
2280 
2281 	if (!sci)
2282 		return -EROFS;
2283 
2284 	nilfs_transaction_lock(sb, &ti, 0);
2285 
2286 	ii = NILFS_I(inode);
2287 	if (test_bit(NILFS_I_INODE_SYNC, &ii->i_state) ||
2288 	    nilfs_test_opt(nilfs, STRICT_ORDER) ||
2289 	    test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags) ||
2290 	    nilfs_discontinued(nilfs)) {
2291 		nilfs_transaction_unlock(sb);
2292 		err = nilfs_segctor_sync(sci);
2293 		return err;
2294 	}
2295 
2296 	spin_lock(&nilfs->ns_inode_lock);
2297 	if (!test_bit(NILFS_I_QUEUED, &ii->i_state) &&
2298 	    !test_bit(NILFS_I_BUSY, &ii->i_state)) {
2299 		spin_unlock(&nilfs->ns_inode_lock);
2300 		nilfs_transaction_unlock(sb);
2301 		return 0;
2302 	}
2303 	spin_unlock(&nilfs->ns_inode_lock);
2304 	sci->sc_dsync_inode = ii;
2305 	sci->sc_dsync_start = start;
2306 	sci->sc_dsync_end = end;
2307 
2308 	err = nilfs_segctor_do_construct(sci, SC_LSEG_DSYNC);
2309 	if (!err)
2310 		nilfs->ns_flushed_device = 0;
2311 
2312 	nilfs_transaction_unlock(sb);
2313 	return err;
2314 }
2315 
2316 #define FLUSH_FILE_BIT	(0x1) /* data file only */
2317 #define FLUSH_DAT_BIT	BIT(NILFS_DAT_INO) /* DAT only */
2318 
2319 /**
2320  * nilfs_segctor_accept - record accepted sequence count of log-write requests
2321  * @sci: segment constructor object
2322  */
2323 static void nilfs_segctor_accept(struct nilfs_sc_info *sci)
2324 {
2325 	spin_lock(&sci->sc_state_lock);
2326 	sci->sc_seq_accepted = sci->sc_seq_request;
2327 	spin_unlock(&sci->sc_state_lock);
2328 	del_timer_sync(&sci->sc_timer);
2329 }
2330 
2331 /**
2332  * nilfs_segctor_notify - notify the result of request to caller threads
2333  * @sci: segment constructor object
2334  * @mode: mode of log forming
2335  * @err: error code to be notified
2336  */
2337 static void nilfs_segctor_notify(struct nilfs_sc_info *sci, int mode, int err)
2338 {
2339 	/* Clear requests (even when the construction failed) */
2340 	spin_lock(&sci->sc_state_lock);
2341 
2342 	if (mode == SC_LSEG_SR) {
2343 		sci->sc_state &= ~NILFS_SEGCTOR_COMMIT;
2344 		sci->sc_seq_done = sci->sc_seq_accepted;
2345 		nilfs_segctor_wakeup(sci, err);
2346 		sci->sc_flush_request = 0;
2347 	} else {
2348 		if (mode == SC_FLUSH_FILE)
2349 			sci->sc_flush_request &= ~FLUSH_FILE_BIT;
2350 		else if (mode == SC_FLUSH_DAT)
2351 			sci->sc_flush_request &= ~FLUSH_DAT_BIT;
2352 
2353 		/* re-enable timer if checkpoint creation was not done */
2354 		if ((sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
2355 		    time_before(jiffies, sci->sc_timer.expires))
2356 			add_timer(&sci->sc_timer);
2357 	}
2358 	spin_unlock(&sci->sc_state_lock);
2359 }
2360 
2361 /**
2362  * nilfs_segctor_construct - form logs and write them to disk
2363  * @sci: segment constructor object
2364  * @mode: mode of log forming
2365  */
2366 static int nilfs_segctor_construct(struct nilfs_sc_info *sci, int mode)
2367 {
2368 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2369 	struct nilfs_super_block **sbp;
2370 	int err = 0;
2371 
2372 	nilfs_segctor_accept(sci);
2373 
2374 	if (nilfs_discontinued(nilfs))
2375 		mode = SC_LSEG_SR;
2376 	if (!nilfs_segctor_confirm(sci))
2377 		err = nilfs_segctor_do_construct(sci, mode);
2378 
2379 	if (likely(!err)) {
2380 		if (mode != SC_FLUSH_DAT)
2381 			atomic_set(&nilfs->ns_ndirtyblks, 0);
2382 		if (test_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags) &&
2383 		    nilfs_discontinued(nilfs)) {
2384 			down_write(&nilfs->ns_sem);
2385 			err = -EIO;
2386 			sbp = nilfs_prepare_super(sci->sc_super,
2387 						  nilfs_sb_will_flip(nilfs));
2388 			if (likely(sbp)) {
2389 				nilfs_set_log_cursor(sbp[0], nilfs);
2390 				err = nilfs_commit_super(sci->sc_super,
2391 							 NILFS_SB_COMMIT);
2392 			}
2393 			up_write(&nilfs->ns_sem);
2394 		}
2395 	}
2396 
2397 	nilfs_segctor_notify(sci, mode, err);
2398 	return err;
2399 }
2400 
2401 static void nilfs_construction_timeout(struct timer_list *t)
2402 {
2403 	struct nilfs_sc_info *sci = from_timer(sci, t, sc_timer);
2404 
2405 	wake_up_process(sci->sc_timer_task);
2406 }
2407 
2408 static void
2409 nilfs_remove_written_gcinodes(struct the_nilfs *nilfs, struct list_head *head)
2410 {
2411 	struct nilfs_inode_info *ii, *n;
2412 
2413 	list_for_each_entry_safe(ii, n, head, i_dirty) {
2414 		if (!test_bit(NILFS_I_UPDATED, &ii->i_state))
2415 			continue;
2416 		list_del_init(&ii->i_dirty);
2417 		truncate_inode_pages(&ii->vfs_inode.i_data, 0);
2418 		nilfs_btnode_cache_clear(&ii->i_btnode_cache);
2419 		iput(&ii->vfs_inode);
2420 	}
2421 }
2422 
2423 int nilfs_clean_segments(struct super_block *sb, struct nilfs_argv *argv,
2424 			 void **kbufs)
2425 {
2426 	struct the_nilfs *nilfs = sb->s_fs_info;
2427 	struct nilfs_sc_info *sci = nilfs->ns_writer;
2428 	struct nilfs_transaction_info ti;
2429 	int err;
2430 
2431 	if (unlikely(!sci))
2432 		return -EROFS;
2433 
2434 	nilfs_transaction_lock(sb, &ti, 1);
2435 
2436 	err = nilfs_mdt_save_to_shadow_map(nilfs->ns_dat);
2437 	if (unlikely(err))
2438 		goto out_unlock;
2439 
2440 	err = nilfs_ioctl_prepare_clean_segments(nilfs, argv, kbufs);
2441 	if (unlikely(err)) {
2442 		nilfs_mdt_restore_from_shadow_map(nilfs->ns_dat);
2443 		goto out_unlock;
2444 	}
2445 
2446 	sci->sc_freesegs = kbufs[4];
2447 	sci->sc_nfreesegs = argv[4].v_nmembs;
2448 	list_splice_tail_init(&nilfs->ns_gc_inodes, &sci->sc_gc_inodes);
2449 
2450 	for (;;) {
2451 		err = nilfs_segctor_construct(sci, SC_LSEG_SR);
2452 		nilfs_remove_written_gcinodes(nilfs, &sci->sc_gc_inodes);
2453 
2454 		if (likely(!err))
2455 			break;
2456 
2457 		nilfs_warn(sb, "error %d cleaning segments", err);
2458 		set_current_state(TASK_INTERRUPTIBLE);
2459 		schedule_timeout(sci->sc_interval);
2460 	}
2461 	if (nilfs_test_opt(nilfs, DISCARD)) {
2462 		int ret = nilfs_discard_segments(nilfs, sci->sc_freesegs,
2463 						 sci->sc_nfreesegs);
2464 		if (ret) {
2465 			nilfs_warn(sb,
2466 				   "error %d on discard request, turning discards off for the device",
2467 				   ret);
2468 			nilfs_clear_opt(nilfs, DISCARD);
2469 		}
2470 	}
2471 
2472  out_unlock:
2473 	sci->sc_freesegs = NULL;
2474 	sci->sc_nfreesegs = 0;
2475 	nilfs_mdt_clear_shadow_map(nilfs->ns_dat);
2476 	nilfs_transaction_unlock(sb);
2477 	return err;
2478 }
2479 
2480 static void nilfs_segctor_thread_construct(struct nilfs_sc_info *sci, int mode)
2481 {
2482 	struct nilfs_transaction_info ti;
2483 
2484 	nilfs_transaction_lock(sci->sc_super, &ti, 0);
2485 	nilfs_segctor_construct(sci, mode);
2486 
2487 	/*
2488 	 * Unclosed segment should be retried.  We do this using sc_timer.
2489 	 * Timeout of sc_timer will invoke complete construction which leads
2490 	 * to close the current logical segment.
2491 	 */
2492 	if (test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags))
2493 		nilfs_segctor_start_timer(sci);
2494 
2495 	nilfs_transaction_unlock(sci->sc_super);
2496 }
2497 
2498 static void nilfs_segctor_do_immediate_flush(struct nilfs_sc_info *sci)
2499 {
2500 	int mode = 0;
2501 
2502 	spin_lock(&sci->sc_state_lock);
2503 	mode = (sci->sc_flush_request & FLUSH_DAT_BIT) ?
2504 		SC_FLUSH_DAT : SC_FLUSH_FILE;
2505 	spin_unlock(&sci->sc_state_lock);
2506 
2507 	if (mode) {
2508 		nilfs_segctor_do_construct(sci, mode);
2509 
2510 		spin_lock(&sci->sc_state_lock);
2511 		sci->sc_flush_request &= (mode == SC_FLUSH_FILE) ?
2512 			~FLUSH_FILE_BIT : ~FLUSH_DAT_BIT;
2513 		spin_unlock(&sci->sc_state_lock);
2514 	}
2515 	clear_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags);
2516 }
2517 
2518 static int nilfs_segctor_flush_mode(struct nilfs_sc_info *sci)
2519 {
2520 	if (!test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags) ||
2521 	    time_before(jiffies, sci->sc_lseg_stime + sci->sc_mjcp_freq)) {
2522 		if (!(sci->sc_flush_request & ~FLUSH_FILE_BIT))
2523 			return SC_FLUSH_FILE;
2524 		else if (!(sci->sc_flush_request & ~FLUSH_DAT_BIT))
2525 			return SC_FLUSH_DAT;
2526 	}
2527 	return SC_LSEG_SR;
2528 }
2529 
2530 /**
2531  * nilfs_segctor_thread - main loop of the segment constructor thread.
2532  * @arg: pointer to a struct nilfs_sc_info.
2533  *
2534  * nilfs_segctor_thread() initializes a timer and serves as a daemon
2535  * to execute segment constructions.
2536  */
2537 static int nilfs_segctor_thread(void *arg)
2538 {
2539 	struct nilfs_sc_info *sci = (struct nilfs_sc_info *)arg;
2540 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2541 	int timeout = 0;
2542 
2543 	sci->sc_timer_task = current;
2544 
2545 	/* start sync. */
2546 	sci->sc_task = current;
2547 	wake_up(&sci->sc_wait_task); /* for nilfs_segctor_start_thread() */
2548 	nilfs_info(sci->sc_super,
2549 		   "segctord starting. Construction interval = %lu seconds, CP frequency < %lu seconds",
2550 		   sci->sc_interval / HZ, sci->sc_mjcp_freq / HZ);
2551 
2552 	spin_lock(&sci->sc_state_lock);
2553  loop:
2554 	for (;;) {
2555 		int mode;
2556 
2557 		if (sci->sc_state & NILFS_SEGCTOR_QUIT)
2558 			goto end_thread;
2559 
2560 		if (timeout || sci->sc_seq_request != sci->sc_seq_done)
2561 			mode = SC_LSEG_SR;
2562 		else if (sci->sc_flush_request)
2563 			mode = nilfs_segctor_flush_mode(sci);
2564 		else
2565 			break;
2566 
2567 		spin_unlock(&sci->sc_state_lock);
2568 		nilfs_segctor_thread_construct(sci, mode);
2569 		spin_lock(&sci->sc_state_lock);
2570 		timeout = 0;
2571 	}
2572 
2573 
2574 	if (freezing(current)) {
2575 		spin_unlock(&sci->sc_state_lock);
2576 		try_to_freeze();
2577 		spin_lock(&sci->sc_state_lock);
2578 	} else {
2579 		DEFINE_WAIT(wait);
2580 		int should_sleep = 1;
2581 
2582 		prepare_to_wait(&sci->sc_wait_daemon, &wait,
2583 				TASK_INTERRUPTIBLE);
2584 
2585 		if (sci->sc_seq_request != sci->sc_seq_done)
2586 			should_sleep = 0;
2587 		else if (sci->sc_flush_request)
2588 			should_sleep = 0;
2589 		else if (sci->sc_state & NILFS_SEGCTOR_COMMIT)
2590 			should_sleep = time_before(jiffies,
2591 					sci->sc_timer.expires);
2592 
2593 		if (should_sleep) {
2594 			spin_unlock(&sci->sc_state_lock);
2595 			schedule();
2596 			spin_lock(&sci->sc_state_lock);
2597 		}
2598 		finish_wait(&sci->sc_wait_daemon, &wait);
2599 		timeout = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
2600 			   time_after_eq(jiffies, sci->sc_timer.expires));
2601 
2602 		if (nilfs_sb_dirty(nilfs) && nilfs_sb_need_update(nilfs))
2603 			set_nilfs_discontinued(nilfs);
2604 	}
2605 	goto loop;
2606 
2607  end_thread:
2608 	spin_unlock(&sci->sc_state_lock);
2609 
2610 	/* end sync. */
2611 	sci->sc_task = NULL;
2612 	wake_up(&sci->sc_wait_task); /* for nilfs_segctor_kill_thread() */
2613 	return 0;
2614 }
2615 
2616 static int nilfs_segctor_start_thread(struct nilfs_sc_info *sci)
2617 {
2618 	struct task_struct *t;
2619 
2620 	t = kthread_run(nilfs_segctor_thread, sci, "segctord");
2621 	if (IS_ERR(t)) {
2622 		int err = PTR_ERR(t);
2623 
2624 		nilfs_err(sci->sc_super, "error %d creating segctord thread",
2625 			  err);
2626 		return err;
2627 	}
2628 	wait_event(sci->sc_wait_task, sci->sc_task != NULL);
2629 	return 0;
2630 }
2631 
2632 static void nilfs_segctor_kill_thread(struct nilfs_sc_info *sci)
2633 	__acquires(&sci->sc_state_lock)
2634 	__releases(&sci->sc_state_lock)
2635 {
2636 	sci->sc_state |= NILFS_SEGCTOR_QUIT;
2637 
2638 	while (sci->sc_task) {
2639 		wake_up(&sci->sc_wait_daemon);
2640 		spin_unlock(&sci->sc_state_lock);
2641 		wait_event(sci->sc_wait_task, sci->sc_task == NULL);
2642 		spin_lock(&sci->sc_state_lock);
2643 	}
2644 }
2645 
2646 /*
2647  * Setup & clean-up functions
2648  */
2649 static struct nilfs_sc_info *nilfs_segctor_new(struct super_block *sb,
2650 					       struct nilfs_root *root)
2651 {
2652 	struct the_nilfs *nilfs = sb->s_fs_info;
2653 	struct nilfs_sc_info *sci;
2654 
2655 	sci = kzalloc(sizeof(*sci), GFP_KERNEL);
2656 	if (!sci)
2657 		return NULL;
2658 
2659 	sci->sc_super = sb;
2660 
2661 	nilfs_get_root(root);
2662 	sci->sc_root = root;
2663 
2664 	init_waitqueue_head(&sci->sc_wait_request);
2665 	init_waitqueue_head(&sci->sc_wait_daemon);
2666 	init_waitqueue_head(&sci->sc_wait_task);
2667 	spin_lock_init(&sci->sc_state_lock);
2668 	INIT_LIST_HEAD(&sci->sc_dirty_files);
2669 	INIT_LIST_HEAD(&sci->sc_segbufs);
2670 	INIT_LIST_HEAD(&sci->sc_write_logs);
2671 	INIT_LIST_HEAD(&sci->sc_gc_inodes);
2672 	INIT_LIST_HEAD(&sci->sc_iput_queue);
2673 	INIT_WORK(&sci->sc_iput_work, nilfs_iput_work_func);
2674 	timer_setup(&sci->sc_timer, nilfs_construction_timeout, 0);
2675 
2676 	sci->sc_interval = HZ * NILFS_SC_DEFAULT_TIMEOUT;
2677 	sci->sc_mjcp_freq = HZ * NILFS_SC_DEFAULT_SR_FREQ;
2678 	sci->sc_watermark = NILFS_SC_DEFAULT_WATERMARK;
2679 
2680 	if (nilfs->ns_interval)
2681 		sci->sc_interval = HZ * nilfs->ns_interval;
2682 	if (nilfs->ns_watermark)
2683 		sci->sc_watermark = nilfs->ns_watermark;
2684 	return sci;
2685 }
2686 
2687 static void nilfs_segctor_write_out(struct nilfs_sc_info *sci)
2688 {
2689 	int ret, retrycount = NILFS_SC_CLEANUP_RETRY;
2690 
2691 	/*
2692 	 * The segctord thread was stopped and its timer was removed.
2693 	 * But some tasks remain.
2694 	 */
2695 	do {
2696 		struct nilfs_transaction_info ti;
2697 
2698 		nilfs_transaction_lock(sci->sc_super, &ti, 0);
2699 		ret = nilfs_segctor_construct(sci, SC_LSEG_SR);
2700 		nilfs_transaction_unlock(sci->sc_super);
2701 
2702 		flush_work(&sci->sc_iput_work);
2703 
2704 	} while (ret && retrycount-- > 0);
2705 }
2706 
2707 /**
2708  * nilfs_segctor_destroy - destroy the segment constructor.
2709  * @sci: nilfs_sc_info
2710  *
2711  * nilfs_segctor_destroy() kills the segctord thread and frees
2712  * the nilfs_sc_info struct.
2713  * Caller must hold the segment semaphore.
2714  */
2715 static void nilfs_segctor_destroy(struct nilfs_sc_info *sci)
2716 {
2717 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2718 	int flag;
2719 
2720 	up_write(&nilfs->ns_segctor_sem);
2721 
2722 	spin_lock(&sci->sc_state_lock);
2723 	nilfs_segctor_kill_thread(sci);
2724 	flag = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) || sci->sc_flush_request
2725 		|| sci->sc_seq_request != sci->sc_seq_done);
2726 	spin_unlock(&sci->sc_state_lock);
2727 
2728 	if (flush_work(&sci->sc_iput_work))
2729 		flag = true;
2730 
2731 	if (flag || !nilfs_segctor_confirm(sci))
2732 		nilfs_segctor_write_out(sci);
2733 
2734 	if (!list_empty(&sci->sc_dirty_files)) {
2735 		nilfs_warn(sci->sc_super,
2736 			   "disposed unprocessed dirty file(s) when stopping log writer");
2737 		nilfs_dispose_list(nilfs, &sci->sc_dirty_files, 1);
2738 	}
2739 
2740 	if (!list_empty(&sci->sc_iput_queue)) {
2741 		nilfs_warn(sci->sc_super,
2742 			   "disposed unprocessed inode(s) in iput queue when stopping log writer");
2743 		nilfs_dispose_list(nilfs, &sci->sc_iput_queue, 1);
2744 	}
2745 
2746 	WARN_ON(!list_empty(&sci->sc_segbufs));
2747 	WARN_ON(!list_empty(&sci->sc_write_logs));
2748 
2749 	nilfs_put_root(sci->sc_root);
2750 
2751 	down_write(&nilfs->ns_segctor_sem);
2752 
2753 	del_timer_sync(&sci->sc_timer);
2754 	kfree(sci);
2755 }
2756 
2757 /**
2758  * nilfs_attach_log_writer - attach log writer
2759  * @sb: super block instance
2760  * @root: root object of the current filesystem tree
2761  *
2762  * This allocates a log writer object, initializes it, and starts the
2763  * log writer.
2764  *
2765  * Return Value: On success, 0 is returned. On error, one of the following
2766  * negative error code is returned.
2767  *
2768  * %-ENOMEM - Insufficient memory available.
2769  */
2770 int nilfs_attach_log_writer(struct super_block *sb, struct nilfs_root *root)
2771 {
2772 	struct the_nilfs *nilfs = sb->s_fs_info;
2773 	int err;
2774 
2775 	if (nilfs->ns_writer) {
2776 		/*
2777 		 * This happens if the filesystem was remounted
2778 		 * read/write after nilfs_error degenerated it into a
2779 		 * read-only mount.
2780 		 */
2781 		nilfs_detach_log_writer(sb);
2782 	}
2783 
2784 	nilfs->ns_writer = nilfs_segctor_new(sb, root);
2785 	if (!nilfs->ns_writer)
2786 		return -ENOMEM;
2787 
2788 	inode_attach_wb(nilfs->ns_bdev->bd_inode, NULL);
2789 
2790 	err = nilfs_segctor_start_thread(nilfs->ns_writer);
2791 	if (err) {
2792 		kfree(nilfs->ns_writer);
2793 		nilfs->ns_writer = NULL;
2794 	}
2795 	return err;
2796 }
2797 
2798 /**
2799  * nilfs_detach_log_writer - destroy log writer
2800  * @sb: super block instance
2801  *
2802  * This kills log writer daemon, frees the log writer object, and
2803  * destroys list of dirty files.
2804  */
2805 void nilfs_detach_log_writer(struct super_block *sb)
2806 {
2807 	struct the_nilfs *nilfs = sb->s_fs_info;
2808 	LIST_HEAD(garbage_list);
2809 
2810 	down_write(&nilfs->ns_segctor_sem);
2811 	if (nilfs->ns_writer) {
2812 		nilfs_segctor_destroy(nilfs->ns_writer);
2813 		nilfs->ns_writer = NULL;
2814 	}
2815 
2816 	/* Force to free the list of dirty files */
2817 	spin_lock(&nilfs->ns_inode_lock);
2818 	if (!list_empty(&nilfs->ns_dirty_files)) {
2819 		list_splice_init(&nilfs->ns_dirty_files, &garbage_list);
2820 		nilfs_warn(sb,
2821 			   "disposed unprocessed dirty file(s) when detaching log writer");
2822 	}
2823 	spin_unlock(&nilfs->ns_inode_lock);
2824 	up_write(&nilfs->ns_segctor_sem);
2825 
2826 	nilfs_dispose_list(nilfs, &garbage_list, 1);
2827 }
2828