xref: /openbmc/linux/fs/nilfs2/segment.c (revision 68f436a8)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * NILFS segment constructor.
4  *
5  * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
6  *
7  * Written by Ryusuke Konishi.
8  *
9  */
10 
11 #include <linux/pagemap.h>
12 #include <linux/buffer_head.h>
13 #include <linux/writeback.h>
14 #include <linux/bitops.h>
15 #include <linux/bio.h>
16 #include <linux/completion.h>
17 #include <linux/blkdev.h>
18 #include <linux/backing-dev.h>
19 #include <linux/freezer.h>
20 #include <linux/kthread.h>
21 #include <linux/crc32.h>
22 #include <linux/pagevec.h>
23 #include <linux/slab.h>
24 #include <linux/sched/signal.h>
25 
26 #include "nilfs.h"
27 #include "btnode.h"
28 #include "page.h"
29 #include "segment.h"
30 #include "sufile.h"
31 #include "cpfile.h"
32 #include "ifile.h"
33 #include "segbuf.h"
34 
35 
36 /*
37  * Segment constructor
38  */
39 #define SC_N_INODEVEC	16   /* Size of locally allocated inode vector */
40 
41 #define SC_MAX_SEGDELTA 64   /*
42 			      * Upper limit of the number of segments
43 			      * appended in collection retry loop
44 			      */
45 
46 /* Construction mode */
47 enum {
48 	SC_LSEG_SR = 1,	/* Make a logical segment having a super root */
49 	SC_LSEG_DSYNC,	/*
50 			 * Flush data blocks of a given file and make
51 			 * a logical segment without a super root.
52 			 */
53 	SC_FLUSH_FILE,	/*
54 			 * Flush data files, leads to segment writes without
55 			 * creating a checkpoint.
56 			 */
57 	SC_FLUSH_DAT,	/*
58 			 * Flush DAT file.  This also creates segments
59 			 * without a checkpoint.
60 			 */
61 };
62 
63 /* Stage numbers of dirty block collection */
64 enum {
65 	NILFS_ST_INIT = 0,
66 	NILFS_ST_GC,		/* Collecting dirty blocks for GC */
67 	NILFS_ST_FILE,
68 	NILFS_ST_IFILE,
69 	NILFS_ST_CPFILE,
70 	NILFS_ST_SUFILE,
71 	NILFS_ST_DAT,
72 	NILFS_ST_SR,		/* Super root */
73 	NILFS_ST_DSYNC,		/* Data sync blocks */
74 	NILFS_ST_DONE,
75 };
76 
77 #define CREATE_TRACE_POINTS
78 #include <trace/events/nilfs2.h>
79 
80 /*
81  * nilfs_sc_cstage_inc(), nilfs_sc_cstage_set(), nilfs_sc_cstage_get() are
82  * wrapper functions of stage count (nilfs_sc_info->sc_stage.scnt). Users of
83  * the variable must use them because transition of stage count must involve
84  * trace events (trace_nilfs2_collection_stage_transition).
85  *
86  * nilfs_sc_cstage_get() isn't required for the above purpose because it doesn't
87  * produce tracepoint events. It is provided just for making the intention
88  * clear.
89  */
90 static inline void nilfs_sc_cstage_inc(struct nilfs_sc_info *sci)
91 {
92 	sci->sc_stage.scnt++;
93 	trace_nilfs2_collection_stage_transition(sci);
94 }
95 
96 static inline void nilfs_sc_cstage_set(struct nilfs_sc_info *sci, int next_scnt)
97 {
98 	sci->sc_stage.scnt = next_scnt;
99 	trace_nilfs2_collection_stage_transition(sci);
100 }
101 
102 static inline int nilfs_sc_cstage_get(struct nilfs_sc_info *sci)
103 {
104 	return sci->sc_stage.scnt;
105 }
106 
107 /* State flags of collection */
108 #define NILFS_CF_NODE		0x0001	/* Collecting node blocks */
109 #define NILFS_CF_IFILE_STARTED	0x0002	/* IFILE stage has started */
110 #define NILFS_CF_SUFREED	0x0004	/* segment usages has been freed */
111 #define NILFS_CF_HISTORY_MASK	(NILFS_CF_IFILE_STARTED | NILFS_CF_SUFREED)
112 
113 /* Operations depending on the construction mode and file type */
114 struct nilfs_sc_operations {
115 	int (*collect_data)(struct nilfs_sc_info *, struct buffer_head *,
116 			    struct inode *);
117 	int (*collect_node)(struct nilfs_sc_info *, struct buffer_head *,
118 			    struct inode *);
119 	int (*collect_bmap)(struct nilfs_sc_info *, struct buffer_head *,
120 			    struct inode *);
121 	void (*write_data_binfo)(struct nilfs_sc_info *,
122 				 struct nilfs_segsum_pointer *,
123 				 union nilfs_binfo *);
124 	void (*write_node_binfo)(struct nilfs_sc_info *,
125 				 struct nilfs_segsum_pointer *,
126 				 union nilfs_binfo *);
127 };
128 
129 /*
130  * Other definitions
131  */
132 static void nilfs_segctor_start_timer(struct nilfs_sc_info *);
133 static void nilfs_segctor_do_flush(struct nilfs_sc_info *, int);
134 static void nilfs_segctor_do_immediate_flush(struct nilfs_sc_info *);
135 static void nilfs_dispose_list(struct the_nilfs *, struct list_head *, int);
136 
137 #define nilfs_cnt32_ge(a, b)   \
138 	(typecheck(__u32, a) && typecheck(__u32, b) && \
139 	 ((__s32)(a) - (__s32)(b) >= 0))
140 
141 static int nilfs_prepare_segment_lock(struct super_block *sb,
142 				      struct nilfs_transaction_info *ti)
143 {
144 	struct nilfs_transaction_info *cur_ti = current->journal_info;
145 	void *save = NULL;
146 
147 	if (cur_ti) {
148 		if (cur_ti->ti_magic == NILFS_TI_MAGIC)
149 			return ++cur_ti->ti_count;
150 
151 		/*
152 		 * If journal_info field is occupied by other FS,
153 		 * it is saved and will be restored on
154 		 * nilfs_transaction_commit().
155 		 */
156 		nilfs_warn(sb, "journal info from a different FS");
157 		save = current->journal_info;
158 	}
159 	if (!ti) {
160 		ti = kmem_cache_alloc(nilfs_transaction_cachep, GFP_NOFS);
161 		if (!ti)
162 			return -ENOMEM;
163 		ti->ti_flags = NILFS_TI_DYNAMIC_ALLOC;
164 	} else {
165 		ti->ti_flags = 0;
166 	}
167 	ti->ti_count = 0;
168 	ti->ti_save = save;
169 	ti->ti_magic = NILFS_TI_MAGIC;
170 	current->journal_info = ti;
171 	return 0;
172 }
173 
174 /**
175  * nilfs_transaction_begin - start indivisible file operations.
176  * @sb: super block
177  * @ti: nilfs_transaction_info
178  * @vacancy_check: flags for vacancy rate checks
179  *
180  * nilfs_transaction_begin() acquires a reader/writer semaphore, called
181  * the segment semaphore, to make a segment construction and write tasks
182  * exclusive.  The function is used with nilfs_transaction_commit() in pairs.
183  * The region enclosed by these two functions can be nested.  To avoid a
184  * deadlock, the semaphore is only acquired or released in the outermost call.
185  *
186  * This function allocates a nilfs_transaction_info struct to keep context
187  * information on it.  It is initialized and hooked onto the current task in
188  * the outermost call.  If a pre-allocated struct is given to @ti, it is used
189  * instead; otherwise a new struct is assigned from a slab.
190  *
191  * When @vacancy_check flag is set, this function will check the amount of
192  * free space, and will wait for the GC to reclaim disk space if low capacity.
193  *
194  * Return Value: On success, 0 is returned. On error, one of the following
195  * negative error code is returned.
196  *
197  * %-ENOMEM - Insufficient memory available.
198  *
199  * %-ENOSPC - No space left on device
200  */
201 int nilfs_transaction_begin(struct super_block *sb,
202 			    struct nilfs_transaction_info *ti,
203 			    int vacancy_check)
204 {
205 	struct the_nilfs *nilfs;
206 	int ret = nilfs_prepare_segment_lock(sb, ti);
207 	struct nilfs_transaction_info *trace_ti;
208 
209 	if (unlikely(ret < 0))
210 		return ret;
211 	if (ret > 0) {
212 		trace_ti = current->journal_info;
213 
214 		trace_nilfs2_transaction_transition(sb, trace_ti,
215 				    trace_ti->ti_count, trace_ti->ti_flags,
216 				    TRACE_NILFS2_TRANSACTION_BEGIN);
217 		return 0;
218 	}
219 
220 	sb_start_intwrite(sb);
221 
222 	nilfs = sb->s_fs_info;
223 	down_read(&nilfs->ns_segctor_sem);
224 	if (vacancy_check && nilfs_near_disk_full(nilfs)) {
225 		up_read(&nilfs->ns_segctor_sem);
226 		ret = -ENOSPC;
227 		goto failed;
228 	}
229 
230 	trace_ti = current->journal_info;
231 	trace_nilfs2_transaction_transition(sb, trace_ti, trace_ti->ti_count,
232 					    trace_ti->ti_flags,
233 					    TRACE_NILFS2_TRANSACTION_BEGIN);
234 	return 0;
235 
236  failed:
237 	ti = current->journal_info;
238 	current->journal_info = ti->ti_save;
239 	if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
240 		kmem_cache_free(nilfs_transaction_cachep, ti);
241 	sb_end_intwrite(sb);
242 	return ret;
243 }
244 
245 /**
246  * nilfs_transaction_commit - commit indivisible file operations.
247  * @sb: super block
248  *
249  * nilfs_transaction_commit() releases the read semaphore which is
250  * acquired by nilfs_transaction_begin(). This is only performed
251  * in outermost call of this function.  If a commit flag is set,
252  * nilfs_transaction_commit() sets a timer to start the segment
253  * constructor.  If a sync flag is set, it starts construction
254  * directly.
255  */
256 int nilfs_transaction_commit(struct super_block *sb)
257 {
258 	struct nilfs_transaction_info *ti = current->journal_info;
259 	struct the_nilfs *nilfs = sb->s_fs_info;
260 	int err = 0;
261 
262 	BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
263 	ti->ti_flags |= NILFS_TI_COMMIT;
264 	if (ti->ti_count > 0) {
265 		ti->ti_count--;
266 		trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
267 			    ti->ti_flags, TRACE_NILFS2_TRANSACTION_COMMIT);
268 		return 0;
269 	}
270 	if (nilfs->ns_writer) {
271 		struct nilfs_sc_info *sci = nilfs->ns_writer;
272 
273 		if (ti->ti_flags & NILFS_TI_COMMIT)
274 			nilfs_segctor_start_timer(sci);
275 		if (atomic_read(&nilfs->ns_ndirtyblks) > sci->sc_watermark)
276 			nilfs_segctor_do_flush(sci, 0);
277 	}
278 	up_read(&nilfs->ns_segctor_sem);
279 	trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
280 			    ti->ti_flags, TRACE_NILFS2_TRANSACTION_COMMIT);
281 
282 	current->journal_info = ti->ti_save;
283 
284 	if (ti->ti_flags & NILFS_TI_SYNC)
285 		err = nilfs_construct_segment(sb);
286 	if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
287 		kmem_cache_free(nilfs_transaction_cachep, ti);
288 	sb_end_intwrite(sb);
289 	return err;
290 }
291 
292 void nilfs_transaction_abort(struct super_block *sb)
293 {
294 	struct nilfs_transaction_info *ti = current->journal_info;
295 	struct the_nilfs *nilfs = sb->s_fs_info;
296 
297 	BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
298 	if (ti->ti_count > 0) {
299 		ti->ti_count--;
300 		trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
301 			    ti->ti_flags, TRACE_NILFS2_TRANSACTION_ABORT);
302 		return;
303 	}
304 	up_read(&nilfs->ns_segctor_sem);
305 
306 	trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
307 		    ti->ti_flags, TRACE_NILFS2_TRANSACTION_ABORT);
308 
309 	current->journal_info = ti->ti_save;
310 	if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
311 		kmem_cache_free(nilfs_transaction_cachep, ti);
312 	sb_end_intwrite(sb);
313 }
314 
315 void nilfs_relax_pressure_in_lock(struct super_block *sb)
316 {
317 	struct the_nilfs *nilfs = sb->s_fs_info;
318 	struct nilfs_sc_info *sci = nilfs->ns_writer;
319 
320 	if (sb_rdonly(sb) || unlikely(!sci) || !sci->sc_flush_request)
321 		return;
322 
323 	set_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags);
324 	up_read(&nilfs->ns_segctor_sem);
325 
326 	down_write(&nilfs->ns_segctor_sem);
327 	if (sci->sc_flush_request &&
328 	    test_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags)) {
329 		struct nilfs_transaction_info *ti = current->journal_info;
330 
331 		ti->ti_flags |= NILFS_TI_WRITER;
332 		nilfs_segctor_do_immediate_flush(sci);
333 		ti->ti_flags &= ~NILFS_TI_WRITER;
334 	}
335 	downgrade_write(&nilfs->ns_segctor_sem);
336 }
337 
338 static void nilfs_transaction_lock(struct super_block *sb,
339 				   struct nilfs_transaction_info *ti,
340 				   int gcflag)
341 {
342 	struct nilfs_transaction_info *cur_ti = current->journal_info;
343 	struct the_nilfs *nilfs = sb->s_fs_info;
344 	struct nilfs_sc_info *sci = nilfs->ns_writer;
345 
346 	WARN_ON(cur_ti);
347 	ti->ti_flags = NILFS_TI_WRITER;
348 	ti->ti_count = 0;
349 	ti->ti_save = cur_ti;
350 	ti->ti_magic = NILFS_TI_MAGIC;
351 	current->journal_info = ti;
352 
353 	for (;;) {
354 		trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
355 			    ti->ti_flags, TRACE_NILFS2_TRANSACTION_TRYLOCK);
356 
357 		down_write(&nilfs->ns_segctor_sem);
358 		if (!test_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags))
359 			break;
360 
361 		nilfs_segctor_do_immediate_flush(sci);
362 
363 		up_write(&nilfs->ns_segctor_sem);
364 		cond_resched();
365 	}
366 	if (gcflag)
367 		ti->ti_flags |= NILFS_TI_GC;
368 
369 	trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
370 			    ti->ti_flags, TRACE_NILFS2_TRANSACTION_LOCK);
371 }
372 
373 static void nilfs_transaction_unlock(struct super_block *sb)
374 {
375 	struct nilfs_transaction_info *ti = current->journal_info;
376 	struct the_nilfs *nilfs = sb->s_fs_info;
377 
378 	BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
379 	BUG_ON(ti->ti_count > 0);
380 
381 	up_write(&nilfs->ns_segctor_sem);
382 	current->journal_info = ti->ti_save;
383 
384 	trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
385 			    ti->ti_flags, TRACE_NILFS2_TRANSACTION_UNLOCK);
386 }
387 
388 static void *nilfs_segctor_map_segsum_entry(struct nilfs_sc_info *sci,
389 					    struct nilfs_segsum_pointer *ssp,
390 					    unsigned int bytes)
391 {
392 	struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
393 	unsigned int blocksize = sci->sc_super->s_blocksize;
394 	void *p;
395 
396 	if (unlikely(ssp->offset + bytes > blocksize)) {
397 		ssp->offset = 0;
398 		BUG_ON(NILFS_SEGBUF_BH_IS_LAST(ssp->bh,
399 					       &segbuf->sb_segsum_buffers));
400 		ssp->bh = NILFS_SEGBUF_NEXT_BH(ssp->bh);
401 	}
402 	p = ssp->bh->b_data + ssp->offset;
403 	ssp->offset += bytes;
404 	return p;
405 }
406 
407 /**
408  * nilfs_segctor_reset_segment_buffer - reset the current segment buffer
409  * @sci: nilfs_sc_info
410  */
411 static int nilfs_segctor_reset_segment_buffer(struct nilfs_sc_info *sci)
412 {
413 	struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
414 	struct buffer_head *sumbh;
415 	unsigned int sumbytes;
416 	unsigned int flags = 0;
417 	int err;
418 
419 	if (nilfs_doing_gc())
420 		flags = NILFS_SS_GC;
421 	err = nilfs_segbuf_reset(segbuf, flags, sci->sc_seg_ctime, sci->sc_cno);
422 	if (unlikely(err))
423 		return err;
424 
425 	sumbh = NILFS_SEGBUF_FIRST_BH(&segbuf->sb_segsum_buffers);
426 	sumbytes = segbuf->sb_sum.sumbytes;
427 	sci->sc_finfo_ptr.bh = sumbh;  sci->sc_finfo_ptr.offset = sumbytes;
428 	sci->sc_binfo_ptr.bh = sumbh;  sci->sc_binfo_ptr.offset = sumbytes;
429 	sci->sc_blk_cnt = sci->sc_datablk_cnt = 0;
430 	return 0;
431 }
432 
433 /**
434  * nilfs_segctor_zeropad_segsum - zero pad the rest of the segment summary area
435  * @sci: segment constructor object
436  *
437  * nilfs_segctor_zeropad_segsum() zero-fills unallocated space at the end of
438  * the current segment summary block.
439  */
440 static void nilfs_segctor_zeropad_segsum(struct nilfs_sc_info *sci)
441 {
442 	struct nilfs_segsum_pointer *ssp;
443 
444 	ssp = sci->sc_blk_cnt > 0 ? &sci->sc_binfo_ptr : &sci->sc_finfo_ptr;
445 	if (ssp->offset < ssp->bh->b_size)
446 		memset(ssp->bh->b_data + ssp->offset, 0,
447 		       ssp->bh->b_size - ssp->offset);
448 }
449 
450 static int nilfs_segctor_feed_segment(struct nilfs_sc_info *sci)
451 {
452 	sci->sc_nblk_this_inc += sci->sc_curseg->sb_sum.nblocks;
453 	if (NILFS_SEGBUF_IS_LAST(sci->sc_curseg, &sci->sc_segbufs))
454 		return -E2BIG; /*
455 				* The current segment is filled up
456 				* (internal code)
457 				*/
458 	nilfs_segctor_zeropad_segsum(sci);
459 	sci->sc_curseg = NILFS_NEXT_SEGBUF(sci->sc_curseg);
460 	return nilfs_segctor_reset_segment_buffer(sci);
461 }
462 
463 static int nilfs_segctor_add_super_root(struct nilfs_sc_info *sci)
464 {
465 	struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
466 	int err;
467 
468 	if (segbuf->sb_sum.nblocks >= segbuf->sb_rest_blocks) {
469 		err = nilfs_segctor_feed_segment(sci);
470 		if (err)
471 			return err;
472 		segbuf = sci->sc_curseg;
473 	}
474 	err = nilfs_segbuf_extend_payload(segbuf, &segbuf->sb_super_root);
475 	if (likely(!err))
476 		segbuf->sb_sum.flags |= NILFS_SS_SR;
477 	return err;
478 }
479 
480 /*
481  * Functions for making segment summary and payloads
482  */
483 static int nilfs_segctor_segsum_block_required(
484 	struct nilfs_sc_info *sci, const struct nilfs_segsum_pointer *ssp,
485 	unsigned int binfo_size)
486 {
487 	unsigned int blocksize = sci->sc_super->s_blocksize;
488 	/* Size of finfo and binfo is enough small against blocksize */
489 
490 	return ssp->offset + binfo_size +
491 		(!sci->sc_blk_cnt ? sizeof(struct nilfs_finfo) : 0) >
492 		blocksize;
493 }
494 
495 static void nilfs_segctor_begin_finfo(struct nilfs_sc_info *sci,
496 				      struct inode *inode)
497 {
498 	sci->sc_curseg->sb_sum.nfinfo++;
499 	sci->sc_binfo_ptr = sci->sc_finfo_ptr;
500 	nilfs_segctor_map_segsum_entry(
501 		sci, &sci->sc_binfo_ptr, sizeof(struct nilfs_finfo));
502 
503 	if (NILFS_I(inode)->i_root &&
504 	    !test_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags))
505 		set_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
506 	/* skip finfo */
507 }
508 
509 static void nilfs_segctor_end_finfo(struct nilfs_sc_info *sci,
510 				    struct inode *inode)
511 {
512 	struct nilfs_finfo *finfo;
513 	struct nilfs_inode_info *ii;
514 	struct nilfs_segment_buffer *segbuf;
515 	__u64 cno;
516 
517 	if (sci->sc_blk_cnt == 0)
518 		return;
519 
520 	ii = NILFS_I(inode);
521 
522 	if (test_bit(NILFS_I_GCINODE, &ii->i_state))
523 		cno = ii->i_cno;
524 	else if (NILFS_ROOT_METADATA_FILE(inode->i_ino))
525 		cno = 0;
526 	else
527 		cno = sci->sc_cno;
528 
529 	finfo = nilfs_segctor_map_segsum_entry(sci, &sci->sc_finfo_ptr,
530 						 sizeof(*finfo));
531 	finfo->fi_ino = cpu_to_le64(inode->i_ino);
532 	finfo->fi_nblocks = cpu_to_le32(sci->sc_blk_cnt);
533 	finfo->fi_ndatablk = cpu_to_le32(sci->sc_datablk_cnt);
534 	finfo->fi_cno = cpu_to_le64(cno);
535 
536 	segbuf = sci->sc_curseg;
537 	segbuf->sb_sum.sumbytes = sci->sc_binfo_ptr.offset +
538 		sci->sc_super->s_blocksize * (segbuf->sb_sum.nsumblk - 1);
539 	sci->sc_finfo_ptr = sci->sc_binfo_ptr;
540 	sci->sc_blk_cnt = sci->sc_datablk_cnt = 0;
541 }
542 
543 static int nilfs_segctor_add_file_block(struct nilfs_sc_info *sci,
544 					struct buffer_head *bh,
545 					struct inode *inode,
546 					unsigned int binfo_size)
547 {
548 	struct nilfs_segment_buffer *segbuf;
549 	int required, err = 0;
550 
551  retry:
552 	segbuf = sci->sc_curseg;
553 	required = nilfs_segctor_segsum_block_required(
554 		sci, &sci->sc_binfo_ptr, binfo_size);
555 	if (segbuf->sb_sum.nblocks + required + 1 > segbuf->sb_rest_blocks) {
556 		nilfs_segctor_end_finfo(sci, inode);
557 		err = nilfs_segctor_feed_segment(sci);
558 		if (err)
559 			return err;
560 		goto retry;
561 	}
562 	if (unlikely(required)) {
563 		nilfs_segctor_zeropad_segsum(sci);
564 		err = nilfs_segbuf_extend_segsum(segbuf);
565 		if (unlikely(err))
566 			goto failed;
567 	}
568 	if (sci->sc_blk_cnt == 0)
569 		nilfs_segctor_begin_finfo(sci, inode);
570 
571 	nilfs_segctor_map_segsum_entry(sci, &sci->sc_binfo_ptr, binfo_size);
572 	/* Substitution to vblocknr is delayed until update_blocknr() */
573 	nilfs_segbuf_add_file_buffer(segbuf, bh);
574 	sci->sc_blk_cnt++;
575  failed:
576 	return err;
577 }
578 
579 /*
580  * Callback functions that enumerate, mark, and collect dirty blocks
581  */
582 static int nilfs_collect_file_data(struct nilfs_sc_info *sci,
583 				   struct buffer_head *bh, struct inode *inode)
584 {
585 	int err;
586 
587 	err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
588 	if (err < 0)
589 		return err;
590 
591 	err = nilfs_segctor_add_file_block(sci, bh, inode,
592 					   sizeof(struct nilfs_binfo_v));
593 	if (!err)
594 		sci->sc_datablk_cnt++;
595 	return err;
596 }
597 
598 static int nilfs_collect_file_node(struct nilfs_sc_info *sci,
599 				   struct buffer_head *bh,
600 				   struct inode *inode)
601 {
602 	return nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
603 }
604 
605 static int nilfs_collect_file_bmap(struct nilfs_sc_info *sci,
606 				   struct buffer_head *bh,
607 				   struct inode *inode)
608 {
609 	WARN_ON(!buffer_dirty(bh));
610 	return nilfs_segctor_add_file_block(sci, bh, inode, sizeof(__le64));
611 }
612 
613 static void nilfs_write_file_data_binfo(struct nilfs_sc_info *sci,
614 					struct nilfs_segsum_pointer *ssp,
615 					union nilfs_binfo *binfo)
616 {
617 	struct nilfs_binfo_v *binfo_v = nilfs_segctor_map_segsum_entry(
618 		sci, ssp, sizeof(*binfo_v));
619 	*binfo_v = binfo->bi_v;
620 }
621 
622 static void nilfs_write_file_node_binfo(struct nilfs_sc_info *sci,
623 					struct nilfs_segsum_pointer *ssp,
624 					union nilfs_binfo *binfo)
625 {
626 	__le64 *vblocknr = nilfs_segctor_map_segsum_entry(
627 		sci, ssp, sizeof(*vblocknr));
628 	*vblocknr = binfo->bi_v.bi_vblocknr;
629 }
630 
631 static const struct nilfs_sc_operations nilfs_sc_file_ops = {
632 	.collect_data = nilfs_collect_file_data,
633 	.collect_node = nilfs_collect_file_node,
634 	.collect_bmap = nilfs_collect_file_bmap,
635 	.write_data_binfo = nilfs_write_file_data_binfo,
636 	.write_node_binfo = nilfs_write_file_node_binfo,
637 };
638 
639 static int nilfs_collect_dat_data(struct nilfs_sc_info *sci,
640 				  struct buffer_head *bh, struct inode *inode)
641 {
642 	int err;
643 
644 	err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
645 	if (err < 0)
646 		return err;
647 
648 	err = nilfs_segctor_add_file_block(sci, bh, inode, sizeof(__le64));
649 	if (!err)
650 		sci->sc_datablk_cnt++;
651 	return err;
652 }
653 
654 static int nilfs_collect_dat_bmap(struct nilfs_sc_info *sci,
655 				  struct buffer_head *bh, struct inode *inode)
656 {
657 	WARN_ON(!buffer_dirty(bh));
658 	return nilfs_segctor_add_file_block(sci, bh, inode,
659 					    sizeof(struct nilfs_binfo_dat));
660 }
661 
662 static void nilfs_write_dat_data_binfo(struct nilfs_sc_info *sci,
663 				       struct nilfs_segsum_pointer *ssp,
664 				       union nilfs_binfo *binfo)
665 {
666 	__le64 *blkoff = nilfs_segctor_map_segsum_entry(sci, ssp,
667 							  sizeof(*blkoff));
668 	*blkoff = binfo->bi_dat.bi_blkoff;
669 }
670 
671 static void nilfs_write_dat_node_binfo(struct nilfs_sc_info *sci,
672 				       struct nilfs_segsum_pointer *ssp,
673 				       union nilfs_binfo *binfo)
674 {
675 	struct nilfs_binfo_dat *binfo_dat =
676 		nilfs_segctor_map_segsum_entry(sci, ssp, sizeof(*binfo_dat));
677 	*binfo_dat = binfo->bi_dat;
678 }
679 
680 static const struct nilfs_sc_operations nilfs_sc_dat_ops = {
681 	.collect_data = nilfs_collect_dat_data,
682 	.collect_node = nilfs_collect_file_node,
683 	.collect_bmap = nilfs_collect_dat_bmap,
684 	.write_data_binfo = nilfs_write_dat_data_binfo,
685 	.write_node_binfo = nilfs_write_dat_node_binfo,
686 };
687 
688 static const struct nilfs_sc_operations nilfs_sc_dsync_ops = {
689 	.collect_data = nilfs_collect_file_data,
690 	.collect_node = NULL,
691 	.collect_bmap = NULL,
692 	.write_data_binfo = nilfs_write_file_data_binfo,
693 	.write_node_binfo = NULL,
694 };
695 
696 static size_t nilfs_lookup_dirty_data_buffers(struct inode *inode,
697 					      struct list_head *listp,
698 					      size_t nlimit,
699 					      loff_t start, loff_t end)
700 {
701 	struct address_space *mapping = inode->i_mapping;
702 	struct folio_batch fbatch;
703 	pgoff_t index = 0, last = ULONG_MAX;
704 	size_t ndirties = 0;
705 	int i;
706 
707 	if (unlikely(start != 0 || end != LLONG_MAX)) {
708 		/*
709 		 * A valid range is given for sync-ing data pages. The
710 		 * range is rounded to per-page; extra dirty buffers
711 		 * may be included if blocksize < pagesize.
712 		 */
713 		index = start >> PAGE_SHIFT;
714 		last = end >> PAGE_SHIFT;
715 	}
716 	folio_batch_init(&fbatch);
717  repeat:
718 	if (unlikely(index > last) ||
719 	      !filemap_get_folios_tag(mapping, &index, last,
720 		      PAGECACHE_TAG_DIRTY, &fbatch))
721 		return ndirties;
722 
723 	for (i = 0; i < folio_batch_count(&fbatch); i++) {
724 		struct buffer_head *bh, *head;
725 		struct folio *folio = fbatch.folios[i];
726 
727 		folio_lock(folio);
728 		head = folio_buffers(folio);
729 		if (!head) {
730 			create_empty_buffers(&folio->page, i_blocksize(inode), 0);
731 			head = folio_buffers(folio);
732 		}
733 		folio_unlock(folio);
734 
735 		bh = head;
736 		do {
737 			if (!buffer_dirty(bh) || buffer_async_write(bh))
738 				continue;
739 			get_bh(bh);
740 			list_add_tail(&bh->b_assoc_buffers, listp);
741 			ndirties++;
742 			if (unlikely(ndirties >= nlimit)) {
743 				folio_batch_release(&fbatch);
744 				cond_resched();
745 				return ndirties;
746 			}
747 		} while (bh = bh->b_this_page, bh != head);
748 	}
749 	folio_batch_release(&fbatch);
750 	cond_resched();
751 	goto repeat;
752 }
753 
754 static void nilfs_lookup_dirty_node_buffers(struct inode *inode,
755 					    struct list_head *listp)
756 {
757 	struct nilfs_inode_info *ii = NILFS_I(inode);
758 	struct inode *btnc_inode = ii->i_assoc_inode;
759 	struct folio_batch fbatch;
760 	struct buffer_head *bh, *head;
761 	unsigned int i;
762 	pgoff_t index = 0;
763 
764 	if (!btnc_inode)
765 		return;
766 	folio_batch_init(&fbatch);
767 
768 	while (filemap_get_folios_tag(btnc_inode->i_mapping, &index,
769 				(pgoff_t)-1, PAGECACHE_TAG_DIRTY, &fbatch)) {
770 		for (i = 0; i < folio_batch_count(&fbatch); i++) {
771 			bh = head = folio_buffers(fbatch.folios[i]);
772 			do {
773 				if (buffer_dirty(bh) &&
774 						!buffer_async_write(bh)) {
775 					get_bh(bh);
776 					list_add_tail(&bh->b_assoc_buffers,
777 						      listp);
778 				}
779 				bh = bh->b_this_page;
780 			} while (bh != head);
781 		}
782 		folio_batch_release(&fbatch);
783 		cond_resched();
784 	}
785 }
786 
787 static void nilfs_dispose_list(struct the_nilfs *nilfs,
788 			       struct list_head *head, int force)
789 {
790 	struct nilfs_inode_info *ii, *n;
791 	struct nilfs_inode_info *ivec[SC_N_INODEVEC], **pii;
792 	unsigned int nv = 0;
793 
794 	while (!list_empty(head)) {
795 		spin_lock(&nilfs->ns_inode_lock);
796 		list_for_each_entry_safe(ii, n, head, i_dirty) {
797 			list_del_init(&ii->i_dirty);
798 			if (force) {
799 				if (unlikely(ii->i_bh)) {
800 					brelse(ii->i_bh);
801 					ii->i_bh = NULL;
802 				}
803 			} else if (test_bit(NILFS_I_DIRTY, &ii->i_state)) {
804 				set_bit(NILFS_I_QUEUED, &ii->i_state);
805 				list_add_tail(&ii->i_dirty,
806 					      &nilfs->ns_dirty_files);
807 				continue;
808 			}
809 			ivec[nv++] = ii;
810 			if (nv == SC_N_INODEVEC)
811 				break;
812 		}
813 		spin_unlock(&nilfs->ns_inode_lock);
814 
815 		for (pii = ivec; nv > 0; pii++, nv--)
816 			iput(&(*pii)->vfs_inode);
817 	}
818 }
819 
820 static void nilfs_iput_work_func(struct work_struct *work)
821 {
822 	struct nilfs_sc_info *sci = container_of(work, struct nilfs_sc_info,
823 						 sc_iput_work);
824 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
825 
826 	nilfs_dispose_list(nilfs, &sci->sc_iput_queue, 0);
827 }
828 
829 static int nilfs_test_metadata_dirty(struct the_nilfs *nilfs,
830 				     struct nilfs_root *root)
831 {
832 	int ret = 0;
833 
834 	if (nilfs_mdt_fetch_dirty(root->ifile))
835 		ret++;
836 	if (nilfs_mdt_fetch_dirty(nilfs->ns_cpfile))
837 		ret++;
838 	if (nilfs_mdt_fetch_dirty(nilfs->ns_sufile))
839 		ret++;
840 	if ((ret || nilfs_doing_gc()) && nilfs_mdt_fetch_dirty(nilfs->ns_dat))
841 		ret++;
842 	return ret;
843 }
844 
845 static int nilfs_segctor_clean(struct nilfs_sc_info *sci)
846 {
847 	return list_empty(&sci->sc_dirty_files) &&
848 		!test_bit(NILFS_SC_DIRTY, &sci->sc_flags) &&
849 		sci->sc_nfreesegs == 0 &&
850 		(!nilfs_doing_gc() || list_empty(&sci->sc_gc_inodes));
851 }
852 
853 static int nilfs_segctor_confirm(struct nilfs_sc_info *sci)
854 {
855 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
856 	int ret = 0;
857 
858 	if (nilfs_test_metadata_dirty(nilfs, sci->sc_root))
859 		set_bit(NILFS_SC_DIRTY, &sci->sc_flags);
860 
861 	spin_lock(&nilfs->ns_inode_lock);
862 	if (list_empty(&nilfs->ns_dirty_files) && nilfs_segctor_clean(sci))
863 		ret++;
864 
865 	spin_unlock(&nilfs->ns_inode_lock);
866 	return ret;
867 }
868 
869 static void nilfs_segctor_clear_metadata_dirty(struct nilfs_sc_info *sci)
870 {
871 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
872 
873 	nilfs_mdt_clear_dirty(sci->sc_root->ifile);
874 	nilfs_mdt_clear_dirty(nilfs->ns_cpfile);
875 	nilfs_mdt_clear_dirty(nilfs->ns_sufile);
876 	nilfs_mdt_clear_dirty(nilfs->ns_dat);
877 }
878 
879 static int nilfs_segctor_create_checkpoint(struct nilfs_sc_info *sci)
880 {
881 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
882 	struct buffer_head *bh_cp;
883 	struct nilfs_checkpoint *raw_cp;
884 	int err;
885 
886 	/* XXX: this interface will be changed */
887 	err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, 1,
888 					  &raw_cp, &bh_cp);
889 	if (likely(!err)) {
890 		/*
891 		 * The following code is duplicated with cpfile.  But, it is
892 		 * needed to collect the checkpoint even if it was not newly
893 		 * created.
894 		 */
895 		mark_buffer_dirty(bh_cp);
896 		nilfs_mdt_mark_dirty(nilfs->ns_cpfile);
897 		nilfs_cpfile_put_checkpoint(
898 			nilfs->ns_cpfile, nilfs->ns_cno, bh_cp);
899 	} else if (err == -EINVAL || err == -ENOENT) {
900 		nilfs_error(sci->sc_super,
901 			    "checkpoint creation failed due to metadata corruption.");
902 		err = -EIO;
903 	}
904 	return err;
905 }
906 
907 static int nilfs_segctor_fill_in_checkpoint(struct nilfs_sc_info *sci)
908 {
909 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
910 	struct buffer_head *bh_cp;
911 	struct nilfs_checkpoint *raw_cp;
912 	int err;
913 
914 	err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, 0,
915 					  &raw_cp, &bh_cp);
916 	if (unlikely(err)) {
917 		if (err == -EINVAL || err == -ENOENT) {
918 			nilfs_error(sci->sc_super,
919 				    "checkpoint finalization failed due to metadata corruption.");
920 			err = -EIO;
921 		}
922 		goto failed_ibh;
923 	}
924 	raw_cp->cp_snapshot_list.ssl_next = 0;
925 	raw_cp->cp_snapshot_list.ssl_prev = 0;
926 	raw_cp->cp_inodes_count =
927 		cpu_to_le64(atomic64_read(&sci->sc_root->inodes_count));
928 	raw_cp->cp_blocks_count =
929 		cpu_to_le64(atomic64_read(&sci->sc_root->blocks_count));
930 	raw_cp->cp_nblk_inc =
931 		cpu_to_le64(sci->sc_nblk_inc + sci->sc_nblk_this_inc);
932 	raw_cp->cp_create = cpu_to_le64(sci->sc_seg_ctime);
933 	raw_cp->cp_cno = cpu_to_le64(nilfs->ns_cno);
934 
935 	if (test_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags))
936 		nilfs_checkpoint_clear_minor(raw_cp);
937 	else
938 		nilfs_checkpoint_set_minor(raw_cp);
939 
940 	nilfs_write_inode_common(sci->sc_root->ifile,
941 				 &raw_cp->cp_ifile_inode, 1);
942 	nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, bh_cp);
943 	return 0;
944 
945  failed_ibh:
946 	return err;
947 }
948 
949 static void nilfs_fill_in_file_bmap(struct inode *ifile,
950 				    struct nilfs_inode_info *ii)
951 
952 {
953 	struct buffer_head *ibh;
954 	struct nilfs_inode *raw_inode;
955 
956 	if (test_bit(NILFS_I_BMAP, &ii->i_state)) {
957 		ibh = ii->i_bh;
958 		BUG_ON(!ibh);
959 		raw_inode = nilfs_ifile_map_inode(ifile, ii->vfs_inode.i_ino,
960 						  ibh);
961 		nilfs_bmap_write(ii->i_bmap, raw_inode);
962 		nilfs_ifile_unmap_inode(ifile, ii->vfs_inode.i_ino, ibh);
963 	}
964 }
965 
966 static void nilfs_segctor_fill_in_file_bmap(struct nilfs_sc_info *sci)
967 {
968 	struct nilfs_inode_info *ii;
969 
970 	list_for_each_entry(ii, &sci->sc_dirty_files, i_dirty) {
971 		nilfs_fill_in_file_bmap(sci->sc_root->ifile, ii);
972 		set_bit(NILFS_I_COLLECTED, &ii->i_state);
973 	}
974 }
975 
976 static void nilfs_segctor_fill_in_super_root(struct nilfs_sc_info *sci,
977 					     struct the_nilfs *nilfs)
978 {
979 	struct buffer_head *bh_sr;
980 	struct nilfs_super_root *raw_sr;
981 	unsigned int isz, srsz;
982 
983 	bh_sr = NILFS_LAST_SEGBUF(&sci->sc_segbufs)->sb_super_root;
984 
985 	lock_buffer(bh_sr);
986 	raw_sr = (struct nilfs_super_root *)bh_sr->b_data;
987 	isz = nilfs->ns_inode_size;
988 	srsz = NILFS_SR_BYTES(isz);
989 
990 	raw_sr->sr_sum = 0;  /* Ensure initialization within this update */
991 	raw_sr->sr_bytes = cpu_to_le16(srsz);
992 	raw_sr->sr_nongc_ctime
993 		= cpu_to_le64(nilfs_doing_gc() ?
994 			      nilfs->ns_nongc_ctime : sci->sc_seg_ctime);
995 	raw_sr->sr_flags = 0;
996 
997 	nilfs_write_inode_common(nilfs->ns_dat, (void *)raw_sr +
998 				 NILFS_SR_DAT_OFFSET(isz), 1);
999 	nilfs_write_inode_common(nilfs->ns_cpfile, (void *)raw_sr +
1000 				 NILFS_SR_CPFILE_OFFSET(isz), 1);
1001 	nilfs_write_inode_common(nilfs->ns_sufile, (void *)raw_sr +
1002 				 NILFS_SR_SUFILE_OFFSET(isz), 1);
1003 	memset((void *)raw_sr + srsz, 0, nilfs->ns_blocksize - srsz);
1004 	set_buffer_uptodate(bh_sr);
1005 	unlock_buffer(bh_sr);
1006 }
1007 
1008 static void nilfs_redirty_inodes(struct list_head *head)
1009 {
1010 	struct nilfs_inode_info *ii;
1011 
1012 	list_for_each_entry(ii, head, i_dirty) {
1013 		if (test_bit(NILFS_I_COLLECTED, &ii->i_state))
1014 			clear_bit(NILFS_I_COLLECTED, &ii->i_state);
1015 	}
1016 }
1017 
1018 static void nilfs_drop_collected_inodes(struct list_head *head)
1019 {
1020 	struct nilfs_inode_info *ii;
1021 
1022 	list_for_each_entry(ii, head, i_dirty) {
1023 		if (!test_and_clear_bit(NILFS_I_COLLECTED, &ii->i_state))
1024 			continue;
1025 
1026 		clear_bit(NILFS_I_INODE_SYNC, &ii->i_state);
1027 		set_bit(NILFS_I_UPDATED, &ii->i_state);
1028 	}
1029 }
1030 
1031 static int nilfs_segctor_apply_buffers(struct nilfs_sc_info *sci,
1032 				       struct inode *inode,
1033 				       struct list_head *listp,
1034 				       int (*collect)(struct nilfs_sc_info *,
1035 						      struct buffer_head *,
1036 						      struct inode *))
1037 {
1038 	struct buffer_head *bh, *n;
1039 	int err = 0;
1040 
1041 	if (collect) {
1042 		list_for_each_entry_safe(bh, n, listp, b_assoc_buffers) {
1043 			list_del_init(&bh->b_assoc_buffers);
1044 			err = collect(sci, bh, inode);
1045 			brelse(bh);
1046 			if (unlikely(err))
1047 				goto dispose_buffers;
1048 		}
1049 		return 0;
1050 	}
1051 
1052  dispose_buffers:
1053 	while (!list_empty(listp)) {
1054 		bh = list_first_entry(listp, struct buffer_head,
1055 				      b_assoc_buffers);
1056 		list_del_init(&bh->b_assoc_buffers);
1057 		brelse(bh);
1058 	}
1059 	return err;
1060 }
1061 
1062 static size_t nilfs_segctor_buffer_rest(struct nilfs_sc_info *sci)
1063 {
1064 	/* Remaining number of blocks within segment buffer */
1065 	return sci->sc_segbuf_nblocks -
1066 		(sci->sc_nblk_this_inc + sci->sc_curseg->sb_sum.nblocks);
1067 }
1068 
1069 static int nilfs_segctor_scan_file(struct nilfs_sc_info *sci,
1070 				   struct inode *inode,
1071 				   const struct nilfs_sc_operations *sc_ops)
1072 {
1073 	LIST_HEAD(data_buffers);
1074 	LIST_HEAD(node_buffers);
1075 	int err;
1076 
1077 	if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
1078 		size_t n, rest = nilfs_segctor_buffer_rest(sci);
1079 
1080 		n = nilfs_lookup_dirty_data_buffers(
1081 			inode, &data_buffers, rest + 1, 0, LLONG_MAX);
1082 		if (n > rest) {
1083 			err = nilfs_segctor_apply_buffers(
1084 				sci, inode, &data_buffers,
1085 				sc_ops->collect_data);
1086 			BUG_ON(!err); /* always receive -E2BIG or true error */
1087 			goto break_or_fail;
1088 		}
1089 	}
1090 	nilfs_lookup_dirty_node_buffers(inode, &node_buffers);
1091 
1092 	if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
1093 		err = nilfs_segctor_apply_buffers(
1094 			sci, inode, &data_buffers, sc_ops->collect_data);
1095 		if (unlikely(err)) {
1096 			/* dispose node list */
1097 			nilfs_segctor_apply_buffers(
1098 				sci, inode, &node_buffers, NULL);
1099 			goto break_or_fail;
1100 		}
1101 		sci->sc_stage.flags |= NILFS_CF_NODE;
1102 	}
1103 	/* Collect node */
1104 	err = nilfs_segctor_apply_buffers(
1105 		sci, inode, &node_buffers, sc_ops->collect_node);
1106 	if (unlikely(err))
1107 		goto break_or_fail;
1108 
1109 	nilfs_bmap_lookup_dirty_buffers(NILFS_I(inode)->i_bmap, &node_buffers);
1110 	err = nilfs_segctor_apply_buffers(
1111 		sci, inode, &node_buffers, sc_ops->collect_bmap);
1112 	if (unlikely(err))
1113 		goto break_or_fail;
1114 
1115 	nilfs_segctor_end_finfo(sci, inode);
1116 	sci->sc_stage.flags &= ~NILFS_CF_NODE;
1117 
1118  break_or_fail:
1119 	return err;
1120 }
1121 
1122 static int nilfs_segctor_scan_file_dsync(struct nilfs_sc_info *sci,
1123 					 struct inode *inode)
1124 {
1125 	LIST_HEAD(data_buffers);
1126 	size_t n, rest = nilfs_segctor_buffer_rest(sci);
1127 	int err;
1128 
1129 	n = nilfs_lookup_dirty_data_buffers(inode, &data_buffers, rest + 1,
1130 					    sci->sc_dsync_start,
1131 					    sci->sc_dsync_end);
1132 
1133 	err = nilfs_segctor_apply_buffers(sci, inode, &data_buffers,
1134 					  nilfs_collect_file_data);
1135 	if (!err) {
1136 		nilfs_segctor_end_finfo(sci, inode);
1137 		BUG_ON(n > rest);
1138 		/* always receive -E2BIG or true error if n > rest */
1139 	}
1140 	return err;
1141 }
1142 
1143 static int nilfs_segctor_collect_blocks(struct nilfs_sc_info *sci, int mode)
1144 {
1145 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
1146 	struct list_head *head;
1147 	struct nilfs_inode_info *ii;
1148 	size_t ndone;
1149 	int err = 0;
1150 
1151 	switch (nilfs_sc_cstage_get(sci)) {
1152 	case NILFS_ST_INIT:
1153 		/* Pre-processes */
1154 		sci->sc_stage.flags = 0;
1155 
1156 		if (!test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags)) {
1157 			sci->sc_nblk_inc = 0;
1158 			sci->sc_curseg->sb_sum.flags = NILFS_SS_LOGBGN;
1159 			if (mode == SC_LSEG_DSYNC) {
1160 				nilfs_sc_cstage_set(sci, NILFS_ST_DSYNC);
1161 				goto dsync_mode;
1162 			}
1163 		}
1164 
1165 		sci->sc_stage.dirty_file_ptr = NULL;
1166 		sci->sc_stage.gc_inode_ptr = NULL;
1167 		if (mode == SC_FLUSH_DAT) {
1168 			nilfs_sc_cstage_set(sci, NILFS_ST_DAT);
1169 			goto dat_stage;
1170 		}
1171 		nilfs_sc_cstage_inc(sci);
1172 		fallthrough;
1173 	case NILFS_ST_GC:
1174 		if (nilfs_doing_gc()) {
1175 			head = &sci->sc_gc_inodes;
1176 			ii = list_prepare_entry(sci->sc_stage.gc_inode_ptr,
1177 						head, i_dirty);
1178 			list_for_each_entry_continue(ii, head, i_dirty) {
1179 				err = nilfs_segctor_scan_file(
1180 					sci, &ii->vfs_inode,
1181 					&nilfs_sc_file_ops);
1182 				if (unlikely(err)) {
1183 					sci->sc_stage.gc_inode_ptr = list_entry(
1184 						ii->i_dirty.prev,
1185 						struct nilfs_inode_info,
1186 						i_dirty);
1187 					goto break_or_fail;
1188 				}
1189 				set_bit(NILFS_I_COLLECTED, &ii->i_state);
1190 			}
1191 			sci->sc_stage.gc_inode_ptr = NULL;
1192 		}
1193 		nilfs_sc_cstage_inc(sci);
1194 		fallthrough;
1195 	case NILFS_ST_FILE:
1196 		head = &sci->sc_dirty_files;
1197 		ii = list_prepare_entry(sci->sc_stage.dirty_file_ptr, head,
1198 					i_dirty);
1199 		list_for_each_entry_continue(ii, head, i_dirty) {
1200 			clear_bit(NILFS_I_DIRTY, &ii->i_state);
1201 
1202 			err = nilfs_segctor_scan_file(sci, &ii->vfs_inode,
1203 						      &nilfs_sc_file_ops);
1204 			if (unlikely(err)) {
1205 				sci->sc_stage.dirty_file_ptr =
1206 					list_entry(ii->i_dirty.prev,
1207 						   struct nilfs_inode_info,
1208 						   i_dirty);
1209 				goto break_or_fail;
1210 			}
1211 			/* sci->sc_stage.dirty_file_ptr = NILFS_I(inode); */
1212 			/* XXX: required ? */
1213 		}
1214 		sci->sc_stage.dirty_file_ptr = NULL;
1215 		if (mode == SC_FLUSH_FILE) {
1216 			nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1217 			return 0;
1218 		}
1219 		nilfs_sc_cstage_inc(sci);
1220 		sci->sc_stage.flags |= NILFS_CF_IFILE_STARTED;
1221 		fallthrough;
1222 	case NILFS_ST_IFILE:
1223 		err = nilfs_segctor_scan_file(sci, sci->sc_root->ifile,
1224 					      &nilfs_sc_file_ops);
1225 		if (unlikely(err))
1226 			break;
1227 		nilfs_sc_cstage_inc(sci);
1228 		/* Creating a checkpoint */
1229 		err = nilfs_segctor_create_checkpoint(sci);
1230 		if (unlikely(err))
1231 			break;
1232 		fallthrough;
1233 	case NILFS_ST_CPFILE:
1234 		err = nilfs_segctor_scan_file(sci, nilfs->ns_cpfile,
1235 					      &nilfs_sc_file_ops);
1236 		if (unlikely(err))
1237 			break;
1238 		nilfs_sc_cstage_inc(sci);
1239 		fallthrough;
1240 	case NILFS_ST_SUFILE:
1241 		err = nilfs_sufile_freev(nilfs->ns_sufile, sci->sc_freesegs,
1242 					 sci->sc_nfreesegs, &ndone);
1243 		if (unlikely(err)) {
1244 			nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1245 						  sci->sc_freesegs, ndone,
1246 						  NULL);
1247 			break;
1248 		}
1249 		sci->sc_stage.flags |= NILFS_CF_SUFREED;
1250 
1251 		err = nilfs_segctor_scan_file(sci, nilfs->ns_sufile,
1252 					      &nilfs_sc_file_ops);
1253 		if (unlikely(err))
1254 			break;
1255 		nilfs_sc_cstage_inc(sci);
1256 		fallthrough;
1257 	case NILFS_ST_DAT:
1258  dat_stage:
1259 		err = nilfs_segctor_scan_file(sci, nilfs->ns_dat,
1260 					      &nilfs_sc_dat_ops);
1261 		if (unlikely(err))
1262 			break;
1263 		if (mode == SC_FLUSH_DAT) {
1264 			nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1265 			return 0;
1266 		}
1267 		nilfs_sc_cstage_inc(sci);
1268 		fallthrough;
1269 	case NILFS_ST_SR:
1270 		if (mode == SC_LSEG_SR) {
1271 			/* Appending a super root */
1272 			err = nilfs_segctor_add_super_root(sci);
1273 			if (unlikely(err))
1274 				break;
1275 		}
1276 		/* End of a logical segment */
1277 		sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
1278 		nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1279 		return 0;
1280 	case NILFS_ST_DSYNC:
1281  dsync_mode:
1282 		sci->sc_curseg->sb_sum.flags |= NILFS_SS_SYNDT;
1283 		ii = sci->sc_dsync_inode;
1284 		if (!test_bit(NILFS_I_BUSY, &ii->i_state))
1285 			break;
1286 
1287 		err = nilfs_segctor_scan_file_dsync(sci, &ii->vfs_inode);
1288 		if (unlikely(err))
1289 			break;
1290 		sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
1291 		nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1292 		return 0;
1293 	case NILFS_ST_DONE:
1294 		return 0;
1295 	default:
1296 		BUG();
1297 	}
1298 
1299  break_or_fail:
1300 	return err;
1301 }
1302 
1303 /**
1304  * nilfs_segctor_begin_construction - setup segment buffer to make a new log
1305  * @sci: nilfs_sc_info
1306  * @nilfs: nilfs object
1307  */
1308 static int nilfs_segctor_begin_construction(struct nilfs_sc_info *sci,
1309 					    struct the_nilfs *nilfs)
1310 {
1311 	struct nilfs_segment_buffer *segbuf, *prev;
1312 	__u64 nextnum;
1313 	int err, alloc = 0;
1314 
1315 	segbuf = nilfs_segbuf_new(sci->sc_super);
1316 	if (unlikely(!segbuf))
1317 		return -ENOMEM;
1318 
1319 	if (list_empty(&sci->sc_write_logs)) {
1320 		nilfs_segbuf_map(segbuf, nilfs->ns_segnum,
1321 				 nilfs->ns_pseg_offset, nilfs);
1322 		if (segbuf->sb_rest_blocks < NILFS_PSEG_MIN_BLOCKS) {
1323 			nilfs_shift_to_next_segment(nilfs);
1324 			nilfs_segbuf_map(segbuf, nilfs->ns_segnum, 0, nilfs);
1325 		}
1326 
1327 		segbuf->sb_sum.seg_seq = nilfs->ns_seg_seq;
1328 		nextnum = nilfs->ns_nextnum;
1329 
1330 		if (nilfs->ns_segnum == nilfs->ns_nextnum)
1331 			/* Start from the head of a new full segment */
1332 			alloc++;
1333 	} else {
1334 		/* Continue logs */
1335 		prev = NILFS_LAST_SEGBUF(&sci->sc_write_logs);
1336 		nilfs_segbuf_map_cont(segbuf, prev);
1337 		segbuf->sb_sum.seg_seq = prev->sb_sum.seg_seq;
1338 		nextnum = prev->sb_nextnum;
1339 
1340 		if (segbuf->sb_rest_blocks < NILFS_PSEG_MIN_BLOCKS) {
1341 			nilfs_segbuf_map(segbuf, prev->sb_nextnum, 0, nilfs);
1342 			segbuf->sb_sum.seg_seq++;
1343 			alloc++;
1344 		}
1345 	}
1346 
1347 	err = nilfs_sufile_mark_dirty(nilfs->ns_sufile, segbuf->sb_segnum);
1348 	if (err)
1349 		goto failed;
1350 
1351 	if (alloc) {
1352 		err = nilfs_sufile_alloc(nilfs->ns_sufile, &nextnum);
1353 		if (err)
1354 			goto failed;
1355 	}
1356 	nilfs_segbuf_set_next_segnum(segbuf, nextnum, nilfs);
1357 
1358 	BUG_ON(!list_empty(&sci->sc_segbufs));
1359 	list_add_tail(&segbuf->sb_list, &sci->sc_segbufs);
1360 	sci->sc_segbuf_nblocks = segbuf->sb_rest_blocks;
1361 	return 0;
1362 
1363  failed:
1364 	nilfs_segbuf_free(segbuf);
1365 	return err;
1366 }
1367 
1368 static int nilfs_segctor_extend_segments(struct nilfs_sc_info *sci,
1369 					 struct the_nilfs *nilfs, int nadd)
1370 {
1371 	struct nilfs_segment_buffer *segbuf, *prev;
1372 	struct inode *sufile = nilfs->ns_sufile;
1373 	__u64 nextnextnum;
1374 	LIST_HEAD(list);
1375 	int err, ret, i;
1376 
1377 	prev = NILFS_LAST_SEGBUF(&sci->sc_segbufs);
1378 	/*
1379 	 * Since the segment specified with nextnum might be allocated during
1380 	 * the previous construction, the buffer including its segusage may
1381 	 * not be dirty.  The following call ensures that the buffer is dirty
1382 	 * and will pin the buffer on memory until the sufile is written.
1383 	 */
1384 	err = nilfs_sufile_mark_dirty(sufile, prev->sb_nextnum);
1385 	if (unlikely(err))
1386 		return err;
1387 
1388 	for (i = 0; i < nadd; i++) {
1389 		/* extend segment info */
1390 		err = -ENOMEM;
1391 		segbuf = nilfs_segbuf_new(sci->sc_super);
1392 		if (unlikely(!segbuf))
1393 			goto failed;
1394 
1395 		/* map this buffer to region of segment on-disk */
1396 		nilfs_segbuf_map(segbuf, prev->sb_nextnum, 0, nilfs);
1397 		sci->sc_segbuf_nblocks += segbuf->sb_rest_blocks;
1398 
1399 		/* allocate the next next full segment */
1400 		err = nilfs_sufile_alloc(sufile, &nextnextnum);
1401 		if (unlikely(err))
1402 			goto failed_segbuf;
1403 
1404 		segbuf->sb_sum.seg_seq = prev->sb_sum.seg_seq + 1;
1405 		nilfs_segbuf_set_next_segnum(segbuf, nextnextnum, nilfs);
1406 
1407 		list_add_tail(&segbuf->sb_list, &list);
1408 		prev = segbuf;
1409 	}
1410 	list_splice_tail(&list, &sci->sc_segbufs);
1411 	return 0;
1412 
1413  failed_segbuf:
1414 	nilfs_segbuf_free(segbuf);
1415  failed:
1416 	list_for_each_entry(segbuf, &list, sb_list) {
1417 		ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1418 		WARN_ON(ret); /* never fails */
1419 	}
1420 	nilfs_destroy_logs(&list);
1421 	return err;
1422 }
1423 
1424 static void nilfs_free_incomplete_logs(struct list_head *logs,
1425 				       struct the_nilfs *nilfs)
1426 {
1427 	struct nilfs_segment_buffer *segbuf, *prev;
1428 	struct inode *sufile = nilfs->ns_sufile;
1429 	int ret;
1430 
1431 	segbuf = NILFS_FIRST_SEGBUF(logs);
1432 	if (nilfs->ns_nextnum != segbuf->sb_nextnum) {
1433 		ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1434 		WARN_ON(ret); /* never fails */
1435 	}
1436 	if (atomic_read(&segbuf->sb_err)) {
1437 		/* Case 1: The first segment failed */
1438 		if (segbuf->sb_pseg_start != segbuf->sb_fseg_start)
1439 			/*
1440 			 * Case 1a:  Partial segment appended into an existing
1441 			 * segment
1442 			 */
1443 			nilfs_terminate_segment(nilfs, segbuf->sb_fseg_start,
1444 						segbuf->sb_fseg_end);
1445 		else /* Case 1b:  New full segment */
1446 			set_nilfs_discontinued(nilfs);
1447 	}
1448 
1449 	prev = segbuf;
1450 	list_for_each_entry_continue(segbuf, logs, sb_list) {
1451 		if (prev->sb_nextnum != segbuf->sb_nextnum) {
1452 			ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1453 			WARN_ON(ret); /* never fails */
1454 		}
1455 		if (atomic_read(&segbuf->sb_err) &&
1456 		    segbuf->sb_segnum != nilfs->ns_nextnum)
1457 			/* Case 2: extended segment (!= next) failed */
1458 			nilfs_sufile_set_error(sufile, segbuf->sb_segnum);
1459 		prev = segbuf;
1460 	}
1461 }
1462 
1463 static void nilfs_segctor_update_segusage(struct nilfs_sc_info *sci,
1464 					  struct inode *sufile)
1465 {
1466 	struct nilfs_segment_buffer *segbuf;
1467 	unsigned long live_blocks;
1468 	int ret;
1469 
1470 	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1471 		live_blocks = segbuf->sb_sum.nblocks +
1472 			(segbuf->sb_pseg_start - segbuf->sb_fseg_start);
1473 		ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1474 						     live_blocks,
1475 						     sci->sc_seg_ctime);
1476 		WARN_ON(ret); /* always succeed because the segusage is dirty */
1477 	}
1478 }
1479 
1480 static void nilfs_cancel_segusage(struct list_head *logs, struct inode *sufile)
1481 {
1482 	struct nilfs_segment_buffer *segbuf;
1483 	int ret;
1484 
1485 	segbuf = NILFS_FIRST_SEGBUF(logs);
1486 	ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1487 					     segbuf->sb_pseg_start -
1488 					     segbuf->sb_fseg_start, 0);
1489 	WARN_ON(ret); /* always succeed because the segusage is dirty */
1490 
1491 	list_for_each_entry_continue(segbuf, logs, sb_list) {
1492 		ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1493 						     0, 0);
1494 		WARN_ON(ret); /* always succeed */
1495 	}
1496 }
1497 
1498 static void nilfs_segctor_truncate_segments(struct nilfs_sc_info *sci,
1499 					    struct nilfs_segment_buffer *last,
1500 					    struct inode *sufile)
1501 {
1502 	struct nilfs_segment_buffer *segbuf = last;
1503 	int ret;
1504 
1505 	list_for_each_entry_continue(segbuf, &sci->sc_segbufs, sb_list) {
1506 		sci->sc_segbuf_nblocks -= segbuf->sb_rest_blocks;
1507 		ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1508 		WARN_ON(ret);
1509 	}
1510 	nilfs_truncate_logs(&sci->sc_segbufs, last);
1511 }
1512 
1513 
1514 static int nilfs_segctor_collect(struct nilfs_sc_info *sci,
1515 				 struct the_nilfs *nilfs, int mode)
1516 {
1517 	struct nilfs_cstage prev_stage = sci->sc_stage;
1518 	int err, nadd = 1;
1519 
1520 	/* Collection retry loop */
1521 	for (;;) {
1522 		sci->sc_nblk_this_inc = 0;
1523 		sci->sc_curseg = NILFS_FIRST_SEGBUF(&sci->sc_segbufs);
1524 
1525 		err = nilfs_segctor_reset_segment_buffer(sci);
1526 		if (unlikely(err))
1527 			goto failed;
1528 
1529 		err = nilfs_segctor_collect_blocks(sci, mode);
1530 		sci->sc_nblk_this_inc += sci->sc_curseg->sb_sum.nblocks;
1531 		if (!err)
1532 			break;
1533 
1534 		if (unlikely(err != -E2BIG))
1535 			goto failed;
1536 
1537 		/* The current segment is filled up */
1538 		if (mode != SC_LSEG_SR ||
1539 		    nilfs_sc_cstage_get(sci) < NILFS_ST_CPFILE)
1540 			break;
1541 
1542 		nilfs_clear_logs(&sci->sc_segbufs);
1543 
1544 		if (sci->sc_stage.flags & NILFS_CF_SUFREED) {
1545 			err = nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1546 							sci->sc_freesegs,
1547 							sci->sc_nfreesegs,
1548 							NULL);
1549 			WARN_ON(err); /* do not happen */
1550 			sci->sc_stage.flags &= ~NILFS_CF_SUFREED;
1551 		}
1552 
1553 		err = nilfs_segctor_extend_segments(sci, nilfs, nadd);
1554 		if (unlikely(err))
1555 			return err;
1556 
1557 		nadd = min_t(int, nadd << 1, SC_MAX_SEGDELTA);
1558 		sci->sc_stage = prev_stage;
1559 	}
1560 	nilfs_segctor_zeropad_segsum(sci);
1561 	nilfs_segctor_truncate_segments(sci, sci->sc_curseg, nilfs->ns_sufile);
1562 	return 0;
1563 
1564  failed:
1565 	return err;
1566 }
1567 
1568 static void nilfs_list_replace_buffer(struct buffer_head *old_bh,
1569 				      struct buffer_head *new_bh)
1570 {
1571 	BUG_ON(!list_empty(&new_bh->b_assoc_buffers));
1572 
1573 	list_replace_init(&old_bh->b_assoc_buffers, &new_bh->b_assoc_buffers);
1574 	/* The caller must release old_bh */
1575 }
1576 
1577 static int
1578 nilfs_segctor_update_payload_blocknr(struct nilfs_sc_info *sci,
1579 				     struct nilfs_segment_buffer *segbuf,
1580 				     int mode)
1581 {
1582 	struct inode *inode = NULL;
1583 	sector_t blocknr;
1584 	unsigned long nfinfo = segbuf->sb_sum.nfinfo;
1585 	unsigned long nblocks = 0, ndatablk = 0;
1586 	const struct nilfs_sc_operations *sc_op = NULL;
1587 	struct nilfs_segsum_pointer ssp;
1588 	struct nilfs_finfo *finfo = NULL;
1589 	union nilfs_binfo binfo;
1590 	struct buffer_head *bh, *bh_org;
1591 	ino_t ino = 0;
1592 	int err = 0;
1593 
1594 	if (!nfinfo)
1595 		goto out;
1596 
1597 	blocknr = segbuf->sb_pseg_start + segbuf->sb_sum.nsumblk;
1598 	ssp.bh = NILFS_SEGBUF_FIRST_BH(&segbuf->sb_segsum_buffers);
1599 	ssp.offset = sizeof(struct nilfs_segment_summary);
1600 
1601 	list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
1602 		if (bh == segbuf->sb_super_root)
1603 			break;
1604 		if (!finfo) {
1605 			finfo =	nilfs_segctor_map_segsum_entry(
1606 				sci, &ssp, sizeof(*finfo));
1607 			ino = le64_to_cpu(finfo->fi_ino);
1608 			nblocks = le32_to_cpu(finfo->fi_nblocks);
1609 			ndatablk = le32_to_cpu(finfo->fi_ndatablk);
1610 
1611 			inode = bh->b_folio->mapping->host;
1612 
1613 			if (mode == SC_LSEG_DSYNC)
1614 				sc_op = &nilfs_sc_dsync_ops;
1615 			else if (ino == NILFS_DAT_INO)
1616 				sc_op = &nilfs_sc_dat_ops;
1617 			else /* file blocks */
1618 				sc_op = &nilfs_sc_file_ops;
1619 		}
1620 		bh_org = bh;
1621 		get_bh(bh_org);
1622 		err = nilfs_bmap_assign(NILFS_I(inode)->i_bmap, &bh, blocknr,
1623 					&binfo);
1624 		if (bh != bh_org)
1625 			nilfs_list_replace_buffer(bh_org, bh);
1626 		brelse(bh_org);
1627 		if (unlikely(err))
1628 			goto failed_bmap;
1629 
1630 		if (ndatablk > 0)
1631 			sc_op->write_data_binfo(sci, &ssp, &binfo);
1632 		else
1633 			sc_op->write_node_binfo(sci, &ssp, &binfo);
1634 
1635 		blocknr++;
1636 		if (--nblocks == 0) {
1637 			finfo = NULL;
1638 			if (--nfinfo == 0)
1639 				break;
1640 		} else if (ndatablk > 0)
1641 			ndatablk--;
1642 	}
1643  out:
1644 	return 0;
1645 
1646  failed_bmap:
1647 	return err;
1648 }
1649 
1650 static int nilfs_segctor_assign(struct nilfs_sc_info *sci, int mode)
1651 {
1652 	struct nilfs_segment_buffer *segbuf;
1653 	int err;
1654 
1655 	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1656 		err = nilfs_segctor_update_payload_blocknr(sci, segbuf, mode);
1657 		if (unlikely(err))
1658 			return err;
1659 		nilfs_segbuf_fill_in_segsum(segbuf);
1660 	}
1661 	return 0;
1662 }
1663 
1664 static void nilfs_begin_page_io(struct page *page)
1665 {
1666 	if (!page || PageWriteback(page))
1667 		/*
1668 		 * For split b-tree node pages, this function may be called
1669 		 * twice.  We ignore the 2nd or later calls by this check.
1670 		 */
1671 		return;
1672 
1673 	lock_page(page);
1674 	clear_page_dirty_for_io(page);
1675 	set_page_writeback(page);
1676 	unlock_page(page);
1677 }
1678 
1679 static void nilfs_segctor_prepare_write(struct nilfs_sc_info *sci)
1680 {
1681 	struct nilfs_segment_buffer *segbuf;
1682 	struct page *bd_page = NULL, *fs_page = NULL;
1683 
1684 	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1685 		struct buffer_head *bh;
1686 
1687 		list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1688 				    b_assoc_buffers) {
1689 			if (bh->b_page != bd_page) {
1690 				if (bd_page) {
1691 					lock_page(bd_page);
1692 					clear_page_dirty_for_io(bd_page);
1693 					set_page_writeback(bd_page);
1694 					unlock_page(bd_page);
1695 				}
1696 				bd_page = bh->b_page;
1697 			}
1698 		}
1699 
1700 		list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1701 				    b_assoc_buffers) {
1702 			set_buffer_async_write(bh);
1703 			if (bh == segbuf->sb_super_root) {
1704 				if (bh->b_page != bd_page) {
1705 					lock_page(bd_page);
1706 					clear_page_dirty_for_io(bd_page);
1707 					set_page_writeback(bd_page);
1708 					unlock_page(bd_page);
1709 					bd_page = bh->b_page;
1710 				}
1711 				break;
1712 			}
1713 			if (bh->b_page != fs_page) {
1714 				nilfs_begin_page_io(fs_page);
1715 				fs_page = bh->b_page;
1716 			}
1717 		}
1718 	}
1719 	if (bd_page) {
1720 		lock_page(bd_page);
1721 		clear_page_dirty_for_io(bd_page);
1722 		set_page_writeback(bd_page);
1723 		unlock_page(bd_page);
1724 	}
1725 	nilfs_begin_page_io(fs_page);
1726 }
1727 
1728 static int nilfs_segctor_write(struct nilfs_sc_info *sci,
1729 			       struct the_nilfs *nilfs)
1730 {
1731 	int ret;
1732 
1733 	ret = nilfs_write_logs(&sci->sc_segbufs, nilfs);
1734 	list_splice_tail_init(&sci->sc_segbufs, &sci->sc_write_logs);
1735 	return ret;
1736 }
1737 
1738 static void nilfs_end_page_io(struct page *page, int err)
1739 {
1740 	if (!page)
1741 		return;
1742 
1743 	if (buffer_nilfs_node(page_buffers(page)) && !PageWriteback(page)) {
1744 		/*
1745 		 * For b-tree node pages, this function may be called twice
1746 		 * or more because they might be split in a segment.
1747 		 */
1748 		if (PageDirty(page)) {
1749 			/*
1750 			 * For pages holding split b-tree node buffers, dirty
1751 			 * flag on the buffers may be cleared discretely.
1752 			 * In that case, the page is once redirtied for
1753 			 * remaining buffers, and it must be cancelled if
1754 			 * all the buffers get cleaned later.
1755 			 */
1756 			lock_page(page);
1757 			if (nilfs_page_buffers_clean(page))
1758 				__nilfs_clear_page_dirty(page);
1759 			unlock_page(page);
1760 		}
1761 		return;
1762 	}
1763 
1764 	if (!err) {
1765 		if (!nilfs_page_buffers_clean(page))
1766 			__set_page_dirty_nobuffers(page);
1767 		ClearPageError(page);
1768 	} else {
1769 		__set_page_dirty_nobuffers(page);
1770 		SetPageError(page);
1771 	}
1772 
1773 	end_page_writeback(page);
1774 }
1775 
1776 static void nilfs_abort_logs(struct list_head *logs, int err)
1777 {
1778 	struct nilfs_segment_buffer *segbuf;
1779 	struct page *bd_page = NULL, *fs_page = NULL;
1780 	struct buffer_head *bh;
1781 
1782 	if (list_empty(logs))
1783 		return;
1784 
1785 	list_for_each_entry(segbuf, logs, sb_list) {
1786 		list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1787 				    b_assoc_buffers) {
1788 			clear_buffer_uptodate(bh);
1789 			if (bh->b_page != bd_page) {
1790 				if (bd_page)
1791 					end_page_writeback(bd_page);
1792 				bd_page = bh->b_page;
1793 			}
1794 		}
1795 
1796 		list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1797 				    b_assoc_buffers) {
1798 			clear_buffer_async_write(bh);
1799 			if (bh == segbuf->sb_super_root) {
1800 				clear_buffer_uptodate(bh);
1801 				if (bh->b_page != bd_page) {
1802 					end_page_writeback(bd_page);
1803 					bd_page = bh->b_page;
1804 				}
1805 				break;
1806 			}
1807 			if (bh->b_page != fs_page) {
1808 				nilfs_end_page_io(fs_page, err);
1809 				fs_page = bh->b_page;
1810 			}
1811 		}
1812 	}
1813 	if (bd_page)
1814 		end_page_writeback(bd_page);
1815 
1816 	nilfs_end_page_io(fs_page, err);
1817 }
1818 
1819 static void nilfs_segctor_abort_construction(struct nilfs_sc_info *sci,
1820 					     struct the_nilfs *nilfs, int err)
1821 {
1822 	LIST_HEAD(logs);
1823 	int ret;
1824 
1825 	list_splice_tail_init(&sci->sc_write_logs, &logs);
1826 	ret = nilfs_wait_on_logs(&logs);
1827 	nilfs_abort_logs(&logs, ret ? : err);
1828 
1829 	list_splice_tail_init(&sci->sc_segbufs, &logs);
1830 	nilfs_cancel_segusage(&logs, nilfs->ns_sufile);
1831 	nilfs_free_incomplete_logs(&logs, nilfs);
1832 
1833 	if (sci->sc_stage.flags & NILFS_CF_SUFREED) {
1834 		ret = nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1835 						sci->sc_freesegs,
1836 						sci->sc_nfreesegs,
1837 						NULL);
1838 		WARN_ON(ret); /* do not happen */
1839 	}
1840 
1841 	nilfs_destroy_logs(&logs);
1842 }
1843 
1844 static void nilfs_set_next_segment(struct the_nilfs *nilfs,
1845 				   struct nilfs_segment_buffer *segbuf)
1846 {
1847 	nilfs->ns_segnum = segbuf->sb_segnum;
1848 	nilfs->ns_nextnum = segbuf->sb_nextnum;
1849 	nilfs->ns_pseg_offset = segbuf->sb_pseg_start - segbuf->sb_fseg_start
1850 		+ segbuf->sb_sum.nblocks;
1851 	nilfs->ns_seg_seq = segbuf->sb_sum.seg_seq;
1852 	nilfs->ns_ctime = segbuf->sb_sum.ctime;
1853 }
1854 
1855 static void nilfs_segctor_complete_write(struct nilfs_sc_info *sci)
1856 {
1857 	struct nilfs_segment_buffer *segbuf;
1858 	struct page *bd_page = NULL, *fs_page = NULL;
1859 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
1860 	int update_sr = false;
1861 
1862 	list_for_each_entry(segbuf, &sci->sc_write_logs, sb_list) {
1863 		struct buffer_head *bh;
1864 
1865 		list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1866 				    b_assoc_buffers) {
1867 			set_buffer_uptodate(bh);
1868 			clear_buffer_dirty(bh);
1869 			if (bh->b_page != bd_page) {
1870 				if (bd_page)
1871 					end_page_writeback(bd_page);
1872 				bd_page = bh->b_page;
1873 			}
1874 		}
1875 		/*
1876 		 * We assume that the buffers which belong to the same page
1877 		 * continue over the buffer list.
1878 		 * Under this assumption, the last BHs of pages is
1879 		 * identifiable by the discontinuity of bh->b_page
1880 		 * (page != fs_page).
1881 		 *
1882 		 * For B-tree node blocks, however, this assumption is not
1883 		 * guaranteed.  The cleanup code of B-tree node pages needs
1884 		 * special care.
1885 		 */
1886 		list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1887 				    b_assoc_buffers) {
1888 			const unsigned long set_bits = BIT(BH_Uptodate);
1889 			const unsigned long clear_bits =
1890 				(BIT(BH_Dirty) | BIT(BH_Async_Write) |
1891 				 BIT(BH_Delay) | BIT(BH_NILFS_Volatile) |
1892 				 BIT(BH_NILFS_Redirected));
1893 
1894 			set_mask_bits(&bh->b_state, clear_bits, set_bits);
1895 			if (bh == segbuf->sb_super_root) {
1896 				if (bh->b_page != bd_page) {
1897 					end_page_writeback(bd_page);
1898 					bd_page = bh->b_page;
1899 				}
1900 				update_sr = true;
1901 				break;
1902 			}
1903 			if (bh->b_page != fs_page) {
1904 				nilfs_end_page_io(fs_page, 0);
1905 				fs_page = bh->b_page;
1906 			}
1907 		}
1908 
1909 		if (!nilfs_segbuf_simplex(segbuf)) {
1910 			if (segbuf->sb_sum.flags & NILFS_SS_LOGBGN) {
1911 				set_bit(NILFS_SC_UNCLOSED, &sci->sc_flags);
1912 				sci->sc_lseg_stime = jiffies;
1913 			}
1914 			if (segbuf->sb_sum.flags & NILFS_SS_LOGEND)
1915 				clear_bit(NILFS_SC_UNCLOSED, &sci->sc_flags);
1916 		}
1917 	}
1918 	/*
1919 	 * Since pages may continue over multiple segment buffers,
1920 	 * end of the last page must be checked outside of the loop.
1921 	 */
1922 	if (bd_page)
1923 		end_page_writeback(bd_page);
1924 
1925 	nilfs_end_page_io(fs_page, 0);
1926 
1927 	nilfs_drop_collected_inodes(&sci->sc_dirty_files);
1928 
1929 	if (nilfs_doing_gc())
1930 		nilfs_drop_collected_inodes(&sci->sc_gc_inodes);
1931 	else
1932 		nilfs->ns_nongc_ctime = sci->sc_seg_ctime;
1933 
1934 	sci->sc_nblk_inc += sci->sc_nblk_this_inc;
1935 
1936 	segbuf = NILFS_LAST_SEGBUF(&sci->sc_write_logs);
1937 	nilfs_set_next_segment(nilfs, segbuf);
1938 
1939 	if (update_sr) {
1940 		nilfs->ns_flushed_device = 0;
1941 		nilfs_set_last_segment(nilfs, segbuf->sb_pseg_start,
1942 				       segbuf->sb_sum.seg_seq, nilfs->ns_cno++);
1943 
1944 		clear_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
1945 		clear_bit(NILFS_SC_DIRTY, &sci->sc_flags);
1946 		set_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags);
1947 		nilfs_segctor_clear_metadata_dirty(sci);
1948 	} else
1949 		clear_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags);
1950 }
1951 
1952 static int nilfs_segctor_wait(struct nilfs_sc_info *sci)
1953 {
1954 	int ret;
1955 
1956 	ret = nilfs_wait_on_logs(&sci->sc_write_logs);
1957 	if (!ret) {
1958 		nilfs_segctor_complete_write(sci);
1959 		nilfs_destroy_logs(&sci->sc_write_logs);
1960 	}
1961 	return ret;
1962 }
1963 
1964 static int nilfs_segctor_collect_dirty_files(struct nilfs_sc_info *sci,
1965 					     struct the_nilfs *nilfs)
1966 {
1967 	struct nilfs_inode_info *ii, *n;
1968 	struct inode *ifile = sci->sc_root->ifile;
1969 
1970 	spin_lock(&nilfs->ns_inode_lock);
1971  retry:
1972 	list_for_each_entry_safe(ii, n, &nilfs->ns_dirty_files, i_dirty) {
1973 		if (!ii->i_bh) {
1974 			struct buffer_head *ibh;
1975 			int err;
1976 
1977 			spin_unlock(&nilfs->ns_inode_lock);
1978 			err = nilfs_ifile_get_inode_block(
1979 				ifile, ii->vfs_inode.i_ino, &ibh);
1980 			if (unlikely(err)) {
1981 				nilfs_warn(sci->sc_super,
1982 					   "log writer: error %d getting inode block (ino=%lu)",
1983 					   err, ii->vfs_inode.i_ino);
1984 				return err;
1985 			}
1986 			spin_lock(&nilfs->ns_inode_lock);
1987 			if (likely(!ii->i_bh))
1988 				ii->i_bh = ibh;
1989 			else
1990 				brelse(ibh);
1991 			goto retry;
1992 		}
1993 
1994 		// Always redirty the buffer to avoid race condition
1995 		mark_buffer_dirty(ii->i_bh);
1996 		nilfs_mdt_mark_dirty(ifile);
1997 
1998 		clear_bit(NILFS_I_QUEUED, &ii->i_state);
1999 		set_bit(NILFS_I_BUSY, &ii->i_state);
2000 		list_move_tail(&ii->i_dirty, &sci->sc_dirty_files);
2001 	}
2002 	spin_unlock(&nilfs->ns_inode_lock);
2003 
2004 	return 0;
2005 }
2006 
2007 static void nilfs_segctor_drop_written_files(struct nilfs_sc_info *sci,
2008 					     struct the_nilfs *nilfs)
2009 {
2010 	struct nilfs_inode_info *ii, *n;
2011 	int during_mount = !(sci->sc_super->s_flags & SB_ACTIVE);
2012 	int defer_iput = false;
2013 
2014 	spin_lock(&nilfs->ns_inode_lock);
2015 	list_for_each_entry_safe(ii, n, &sci->sc_dirty_files, i_dirty) {
2016 		if (!test_and_clear_bit(NILFS_I_UPDATED, &ii->i_state) ||
2017 		    test_bit(NILFS_I_DIRTY, &ii->i_state))
2018 			continue;
2019 
2020 		clear_bit(NILFS_I_BUSY, &ii->i_state);
2021 		brelse(ii->i_bh);
2022 		ii->i_bh = NULL;
2023 		list_del_init(&ii->i_dirty);
2024 		if (!ii->vfs_inode.i_nlink || during_mount) {
2025 			/*
2026 			 * Defer calling iput() to avoid deadlocks if
2027 			 * i_nlink == 0 or mount is not yet finished.
2028 			 */
2029 			list_add_tail(&ii->i_dirty, &sci->sc_iput_queue);
2030 			defer_iput = true;
2031 		} else {
2032 			spin_unlock(&nilfs->ns_inode_lock);
2033 			iput(&ii->vfs_inode);
2034 			spin_lock(&nilfs->ns_inode_lock);
2035 		}
2036 	}
2037 	spin_unlock(&nilfs->ns_inode_lock);
2038 
2039 	if (defer_iput)
2040 		schedule_work(&sci->sc_iput_work);
2041 }
2042 
2043 /*
2044  * Main procedure of segment constructor
2045  */
2046 static int nilfs_segctor_do_construct(struct nilfs_sc_info *sci, int mode)
2047 {
2048 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2049 	int err;
2050 
2051 	if (sb_rdonly(sci->sc_super))
2052 		return -EROFS;
2053 
2054 	nilfs_sc_cstage_set(sci, NILFS_ST_INIT);
2055 	sci->sc_cno = nilfs->ns_cno;
2056 
2057 	err = nilfs_segctor_collect_dirty_files(sci, nilfs);
2058 	if (unlikely(err))
2059 		goto out;
2060 
2061 	if (nilfs_test_metadata_dirty(nilfs, sci->sc_root))
2062 		set_bit(NILFS_SC_DIRTY, &sci->sc_flags);
2063 
2064 	if (nilfs_segctor_clean(sci))
2065 		goto out;
2066 
2067 	do {
2068 		sci->sc_stage.flags &= ~NILFS_CF_HISTORY_MASK;
2069 
2070 		err = nilfs_segctor_begin_construction(sci, nilfs);
2071 		if (unlikely(err))
2072 			goto out;
2073 
2074 		/* Update time stamp */
2075 		sci->sc_seg_ctime = ktime_get_real_seconds();
2076 
2077 		err = nilfs_segctor_collect(sci, nilfs, mode);
2078 		if (unlikely(err))
2079 			goto failed;
2080 
2081 		/* Avoid empty segment */
2082 		if (nilfs_sc_cstage_get(sci) == NILFS_ST_DONE &&
2083 		    nilfs_segbuf_empty(sci->sc_curseg)) {
2084 			nilfs_segctor_abort_construction(sci, nilfs, 1);
2085 			goto out;
2086 		}
2087 
2088 		err = nilfs_segctor_assign(sci, mode);
2089 		if (unlikely(err))
2090 			goto failed;
2091 
2092 		if (sci->sc_stage.flags & NILFS_CF_IFILE_STARTED)
2093 			nilfs_segctor_fill_in_file_bmap(sci);
2094 
2095 		if (mode == SC_LSEG_SR &&
2096 		    nilfs_sc_cstage_get(sci) >= NILFS_ST_CPFILE) {
2097 			err = nilfs_segctor_fill_in_checkpoint(sci);
2098 			if (unlikely(err))
2099 				goto failed_to_write;
2100 
2101 			nilfs_segctor_fill_in_super_root(sci, nilfs);
2102 		}
2103 		nilfs_segctor_update_segusage(sci, nilfs->ns_sufile);
2104 
2105 		/* Write partial segments */
2106 		nilfs_segctor_prepare_write(sci);
2107 
2108 		nilfs_add_checksums_on_logs(&sci->sc_segbufs,
2109 					    nilfs->ns_crc_seed);
2110 
2111 		err = nilfs_segctor_write(sci, nilfs);
2112 		if (unlikely(err))
2113 			goto failed_to_write;
2114 
2115 		if (nilfs_sc_cstage_get(sci) == NILFS_ST_DONE ||
2116 		    nilfs->ns_blocksize_bits != PAGE_SHIFT) {
2117 			/*
2118 			 * At this point, we avoid double buffering
2119 			 * for blocksize < pagesize because page dirty
2120 			 * flag is turned off during write and dirty
2121 			 * buffers are not properly collected for
2122 			 * pages crossing over segments.
2123 			 */
2124 			err = nilfs_segctor_wait(sci);
2125 			if (err)
2126 				goto failed_to_write;
2127 		}
2128 	} while (nilfs_sc_cstage_get(sci) != NILFS_ST_DONE);
2129 
2130  out:
2131 	nilfs_segctor_drop_written_files(sci, nilfs);
2132 	return err;
2133 
2134  failed_to_write:
2135 	if (sci->sc_stage.flags & NILFS_CF_IFILE_STARTED)
2136 		nilfs_redirty_inodes(&sci->sc_dirty_files);
2137 
2138  failed:
2139 	if (nilfs_doing_gc())
2140 		nilfs_redirty_inodes(&sci->sc_gc_inodes);
2141 	nilfs_segctor_abort_construction(sci, nilfs, err);
2142 	goto out;
2143 }
2144 
2145 /**
2146  * nilfs_segctor_start_timer - set timer of background write
2147  * @sci: nilfs_sc_info
2148  *
2149  * If the timer has already been set, it ignores the new request.
2150  * This function MUST be called within a section locking the segment
2151  * semaphore.
2152  */
2153 static void nilfs_segctor_start_timer(struct nilfs_sc_info *sci)
2154 {
2155 	spin_lock(&sci->sc_state_lock);
2156 	if (!(sci->sc_state & NILFS_SEGCTOR_COMMIT)) {
2157 		sci->sc_timer.expires = jiffies + sci->sc_interval;
2158 		add_timer(&sci->sc_timer);
2159 		sci->sc_state |= NILFS_SEGCTOR_COMMIT;
2160 	}
2161 	spin_unlock(&sci->sc_state_lock);
2162 }
2163 
2164 static void nilfs_segctor_do_flush(struct nilfs_sc_info *sci, int bn)
2165 {
2166 	spin_lock(&sci->sc_state_lock);
2167 	if (!(sci->sc_flush_request & BIT(bn))) {
2168 		unsigned long prev_req = sci->sc_flush_request;
2169 
2170 		sci->sc_flush_request |= BIT(bn);
2171 		if (!prev_req)
2172 			wake_up(&sci->sc_wait_daemon);
2173 	}
2174 	spin_unlock(&sci->sc_state_lock);
2175 }
2176 
2177 /**
2178  * nilfs_flush_segment - trigger a segment construction for resource control
2179  * @sb: super block
2180  * @ino: inode number of the file to be flushed out.
2181  */
2182 void nilfs_flush_segment(struct super_block *sb, ino_t ino)
2183 {
2184 	struct the_nilfs *nilfs = sb->s_fs_info;
2185 	struct nilfs_sc_info *sci = nilfs->ns_writer;
2186 
2187 	if (!sci || nilfs_doing_construction())
2188 		return;
2189 	nilfs_segctor_do_flush(sci, NILFS_MDT_INODE(sb, ino) ? ino : 0);
2190 					/* assign bit 0 to data files */
2191 }
2192 
2193 struct nilfs_segctor_wait_request {
2194 	wait_queue_entry_t	wq;
2195 	__u32		seq;
2196 	int		err;
2197 	atomic_t	done;
2198 };
2199 
2200 static int nilfs_segctor_sync(struct nilfs_sc_info *sci)
2201 {
2202 	struct nilfs_segctor_wait_request wait_req;
2203 	int err = 0;
2204 
2205 	spin_lock(&sci->sc_state_lock);
2206 	init_wait(&wait_req.wq);
2207 	wait_req.err = 0;
2208 	atomic_set(&wait_req.done, 0);
2209 	wait_req.seq = ++sci->sc_seq_request;
2210 	spin_unlock(&sci->sc_state_lock);
2211 
2212 	init_waitqueue_entry(&wait_req.wq, current);
2213 	add_wait_queue(&sci->sc_wait_request, &wait_req.wq);
2214 	set_current_state(TASK_INTERRUPTIBLE);
2215 	wake_up(&sci->sc_wait_daemon);
2216 
2217 	for (;;) {
2218 		if (atomic_read(&wait_req.done)) {
2219 			err = wait_req.err;
2220 			break;
2221 		}
2222 		if (!signal_pending(current)) {
2223 			schedule();
2224 			continue;
2225 		}
2226 		err = -ERESTARTSYS;
2227 		break;
2228 	}
2229 	finish_wait(&sci->sc_wait_request, &wait_req.wq);
2230 	return err;
2231 }
2232 
2233 static void nilfs_segctor_wakeup(struct nilfs_sc_info *sci, int err)
2234 {
2235 	struct nilfs_segctor_wait_request *wrq, *n;
2236 	unsigned long flags;
2237 
2238 	spin_lock_irqsave(&sci->sc_wait_request.lock, flags);
2239 	list_for_each_entry_safe(wrq, n, &sci->sc_wait_request.head, wq.entry) {
2240 		if (!atomic_read(&wrq->done) &&
2241 		    nilfs_cnt32_ge(sci->sc_seq_done, wrq->seq)) {
2242 			wrq->err = err;
2243 			atomic_set(&wrq->done, 1);
2244 		}
2245 		if (atomic_read(&wrq->done)) {
2246 			wrq->wq.func(&wrq->wq,
2247 				     TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
2248 				     0, NULL);
2249 		}
2250 	}
2251 	spin_unlock_irqrestore(&sci->sc_wait_request.lock, flags);
2252 }
2253 
2254 /**
2255  * nilfs_construct_segment - construct a logical segment
2256  * @sb: super block
2257  *
2258  * Return Value: On success, 0 is returned. On errors, one of the following
2259  * negative error code is returned.
2260  *
2261  * %-EROFS - Read only filesystem.
2262  *
2263  * %-EIO - I/O error
2264  *
2265  * %-ENOSPC - No space left on device (only in a panic state).
2266  *
2267  * %-ERESTARTSYS - Interrupted.
2268  *
2269  * %-ENOMEM - Insufficient memory available.
2270  */
2271 int nilfs_construct_segment(struct super_block *sb)
2272 {
2273 	struct the_nilfs *nilfs = sb->s_fs_info;
2274 	struct nilfs_sc_info *sci = nilfs->ns_writer;
2275 	struct nilfs_transaction_info *ti;
2276 
2277 	if (sb_rdonly(sb) || unlikely(!sci))
2278 		return -EROFS;
2279 
2280 	/* A call inside transactions causes a deadlock. */
2281 	BUG_ON((ti = current->journal_info) && ti->ti_magic == NILFS_TI_MAGIC);
2282 
2283 	return nilfs_segctor_sync(sci);
2284 }
2285 
2286 /**
2287  * nilfs_construct_dsync_segment - construct a data-only logical segment
2288  * @sb: super block
2289  * @inode: inode whose data blocks should be written out
2290  * @start: start byte offset
2291  * @end: end byte offset (inclusive)
2292  *
2293  * Return Value: On success, 0 is returned. On errors, one of the following
2294  * negative error code is returned.
2295  *
2296  * %-EROFS - Read only filesystem.
2297  *
2298  * %-EIO - I/O error
2299  *
2300  * %-ENOSPC - No space left on device (only in a panic state).
2301  *
2302  * %-ERESTARTSYS - Interrupted.
2303  *
2304  * %-ENOMEM - Insufficient memory available.
2305  */
2306 int nilfs_construct_dsync_segment(struct super_block *sb, struct inode *inode,
2307 				  loff_t start, loff_t end)
2308 {
2309 	struct the_nilfs *nilfs = sb->s_fs_info;
2310 	struct nilfs_sc_info *sci = nilfs->ns_writer;
2311 	struct nilfs_inode_info *ii;
2312 	struct nilfs_transaction_info ti;
2313 	int err = 0;
2314 
2315 	if (sb_rdonly(sb) || unlikely(!sci))
2316 		return -EROFS;
2317 
2318 	nilfs_transaction_lock(sb, &ti, 0);
2319 
2320 	ii = NILFS_I(inode);
2321 	if (test_bit(NILFS_I_INODE_SYNC, &ii->i_state) ||
2322 	    nilfs_test_opt(nilfs, STRICT_ORDER) ||
2323 	    test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags) ||
2324 	    nilfs_discontinued(nilfs)) {
2325 		nilfs_transaction_unlock(sb);
2326 		err = nilfs_segctor_sync(sci);
2327 		return err;
2328 	}
2329 
2330 	spin_lock(&nilfs->ns_inode_lock);
2331 	if (!test_bit(NILFS_I_QUEUED, &ii->i_state) &&
2332 	    !test_bit(NILFS_I_BUSY, &ii->i_state)) {
2333 		spin_unlock(&nilfs->ns_inode_lock);
2334 		nilfs_transaction_unlock(sb);
2335 		return 0;
2336 	}
2337 	spin_unlock(&nilfs->ns_inode_lock);
2338 	sci->sc_dsync_inode = ii;
2339 	sci->sc_dsync_start = start;
2340 	sci->sc_dsync_end = end;
2341 
2342 	err = nilfs_segctor_do_construct(sci, SC_LSEG_DSYNC);
2343 	if (!err)
2344 		nilfs->ns_flushed_device = 0;
2345 
2346 	nilfs_transaction_unlock(sb);
2347 	return err;
2348 }
2349 
2350 #define FLUSH_FILE_BIT	(0x1) /* data file only */
2351 #define FLUSH_DAT_BIT	BIT(NILFS_DAT_INO) /* DAT only */
2352 
2353 /**
2354  * nilfs_segctor_accept - record accepted sequence count of log-write requests
2355  * @sci: segment constructor object
2356  */
2357 static void nilfs_segctor_accept(struct nilfs_sc_info *sci)
2358 {
2359 	spin_lock(&sci->sc_state_lock);
2360 	sci->sc_seq_accepted = sci->sc_seq_request;
2361 	spin_unlock(&sci->sc_state_lock);
2362 	del_timer_sync(&sci->sc_timer);
2363 }
2364 
2365 /**
2366  * nilfs_segctor_notify - notify the result of request to caller threads
2367  * @sci: segment constructor object
2368  * @mode: mode of log forming
2369  * @err: error code to be notified
2370  */
2371 static void nilfs_segctor_notify(struct nilfs_sc_info *sci, int mode, int err)
2372 {
2373 	/* Clear requests (even when the construction failed) */
2374 	spin_lock(&sci->sc_state_lock);
2375 
2376 	if (mode == SC_LSEG_SR) {
2377 		sci->sc_state &= ~NILFS_SEGCTOR_COMMIT;
2378 		sci->sc_seq_done = sci->sc_seq_accepted;
2379 		nilfs_segctor_wakeup(sci, err);
2380 		sci->sc_flush_request = 0;
2381 	} else {
2382 		if (mode == SC_FLUSH_FILE)
2383 			sci->sc_flush_request &= ~FLUSH_FILE_BIT;
2384 		else if (mode == SC_FLUSH_DAT)
2385 			sci->sc_flush_request &= ~FLUSH_DAT_BIT;
2386 
2387 		/* re-enable timer if checkpoint creation was not done */
2388 		if ((sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
2389 		    time_before(jiffies, sci->sc_timer.expires))
2390 			add_timer(&sci->sc_timer);
2391 	}
2392 	spin_unlock(&sci->sc_state_lock);
2393 }
2394 
2395 /**
2396  * nilfs_segctor_construct - form logs and write them to disk
2397  * @sci: segment constructor object
2398  * @mode: mode of log forming
2399  */
2400 static int nilfs_segctor_construct(struct nilfs_sc_info *sci, int mode)
2401 {
2402 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2403 	struct nilfs_super_block **sbp;
2404 	int err = 0;
2405 
2406 	nilfs_segctor_accept(sci);
2407 
2408 	if (nilfs_discontinued(nilfs))
2409 		mode = SC_LSEG_SR;
2410 	if (!nilfs_segctor_confirm(sci))
2411 		err = nilfs_segctor_do_construct(sci, mode);
2412 
2413 	if (likely(!err)) {
2414 		if (mode != SC_FLUSH_DAT)
2415 			atomic_set(&nilfs->ns_ndirtyblks, 0);
2416 		if (test_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags) &&
2417 		    nilfs_discontinued(nilfs)) {
2418 			down_write(&nilfs->ns_sem);
2419 			err = -EIO;
2420 			sbp = nilfs_prepare_super(sci->sc_super,
2421 						  nilfs_sb_will_flip(nilfs));
2422 			if (likely(sbp)) {
2423 				nilfs_set_log_cursor(sbp[0], nilfs);
2424 				err = nilfs_commit_super(sci->sc_super,
2425 							 NILFS_SB_COMMIT);
2426 			}
2427 			up_write(&nilfs->ns_sem);
2428 		}
2429 	}
2430 
2431 	nilfs_segctor_notify(sci, mode, err);
2432 	return err;
2433 }
2434 
2435 static void nilfs_construction_timeout(struct timer_list *t)
2436 {
2437 	struct nilfs_sc_info *sci = from_timer(sci, t, sc_timer);
2438 
2439 	wake_up_process(sci->sc_timer_task);
2440 }
2441 
2442 static void
2443 nilfs_remove_written_gcinodes(struct the_nilfs *nilfs, struct list_head *head)
2444 {
2445 	struct nilfs_inode_info *ii, *n;
2446 
2447 	list_for_each_entry_safe(ii, n, head, i_dirty) {
2448 		if (!test_bit(NILFS_I_UPDATED, &ii->i_state))
2449 			continue;
2450 		list_del_init(&ii->i_dirty);
2451 		truncate_inode_pages(&ii->vfs_inode.i_data, 0);
2452 		nilfs_btnode_cache_clear(ii->i_assoc_inode->i_mapping);
2453 		iput(&ii->vfs_inode);
2454 	}
2455 }
2456 
2457 int nilfs_clean_segments(struct super_block *sb, struct nilfs_argv *argv,
2458 			 void **kbufs)
2459 {
2460 	struct the_nilfs *nilfs = sb->s_fs_info;
2461 	struct nilfs_sc_info *sci = nilfs->ns_writer;
2462 	struct nilfs_transaction_info ti;
2463 	int err;
2464 
2465 	if (unlikely(!sci))
2466 		return -EROFS;
2467 
2468 	nilfs_transaction_lock(sb, &ti, 1);
2469 
2470 	err = nilfs_mdt_save_to_shadow_map(nilfs->ns_dat);
2471 	if (unlikely(err))
2472 		goto out_unlock;
2473 
2474 	err = nilfs_ioctl_prepare_clean_segments(nilfs, argv, kbufs);
2475 	if (unlikely(err)) {
2476 		nilfs_mdt_restore_from_shadow_map(nilfs->ns_dat);
2477 		goto out_unlock;
2478 	}
2479 
2480 	sci->sc_freesegs = kbufs[4];
2481 	sci->sc_nfreesegs = argv[4].v_nmembs;
2482 	list_splice_tail_init(&nilfs->ns_gc_inodes, &sci->sc_gc_inodes);
2483 
2484 	for (;;) {
2485 		err = nilfs_segctor_construct(sci, SC_LSEG_SR);
2486 		nilfs_remove_written_gcinodes(nilfs, &sci->sc_gc_inodes);
2487 
2488 		if (likely(!err))
2489 			break;
2490 
2491 		nilfs_warn(sb, "error %d cleaning segments", err);
2492 		set_current_state(TASK_INTERRUPTIBLE);
2493 		schedule_timeout(sci->sc_interval);
2494 	}
2495 	if (nilfs_test_opt(nilfs, DISCARD)) {
2496 		int ret = nilfs_discard_segments(nilfs, sci->sc_freesegs,
2497 						 sci->sc_nfreesegs);
2498 		if (ret) {
2499 			nilfs_warn(sb,
2500 				   "error %d on discard request, turning discards off for the device",
2501 				   ret);
2502 			nilfs_clear_opt(nilfs, DISCARD);
2503 		}
2504 	}
2505 
2506  out_unlock:
2507 	sci->sc_freesegs = NULL;
2508 	sci->sc_nfreesegs = 0;
2509 	nilfs_mdt_clear_shadow_map(nilfs->ns_dat);
2510 	nilfs_transaction_unlock(sb);
2511 	return err;
2512 }
2513 
2514 static void nilfs_segctor_thread_construct(struct nilfs_sc_info *sci, int mode)
2515 {
2516 	struct nilfs_transaction_info ti;
2517 
2518 	nilfs_transaction_lock(sci->sc_super, &ti, 0);
2519 	nilfs_segctor_construct(sci, mode);
2520 
2521 	/*
2522 	 * Unclosed segment should be retried.  We do this using sc_timer.
2523 	 * Timeout of sc_timer will invoke complete construction which leads
2524 	 * to close the current logical segment.
2525 	 */
2526 	if (test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags))
2527 		nilfs_segctor_start_timer(sci);
2528 
2529 	nilfs_transaction_unlock(sci->sc_super);
2530 }
2531 
2532 static void nilfs_segctor_do_immediate_flush(struct nilfs_sc_info *sci)
2533 {
2534 	int mode = 0;
2535 
2536 	spin_lock(&sci->sc_state_lock);
2537 	mode = (sci->sc_flush_request & FLUSH_DAT_BIT) ?
2538 		SC_FLUSH_DAT : SC_FLUSH_FILE;
2539 	spin_unlock(&sci->sc_state_lock);
2540 
2541 	if (mode) {
2542 		nilfs_segctor_do_construct(sci, mode);
2543 
2544 		spin_lock(&sci->sc_state_lock);
2545 		sci->sc_flush_request &= (mode == SC_FLUSH_FILE) ?
2546 			~FLUSH_FILE_BIT : ~FLUSH_DAT_BIT;
2547 		spin_unlock(&sci->sc_state_lock);
2548 	}
2549 	clear_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags);
2550 }
2551 
2552 static int nilfs_segctor_flush_mode(struct nilfs_sc_info *sci)
2553 {
2554 	if (!test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags) ||
2555 	    time_before(jiffies, sci->sc_lseg_stime + sci->sc_mjcp_freq)) {
2556 		if (!(sci->sc_flush_request & ~FLUSH_FILE_BIT))
2557 			return SC_FLUSH_FILE;
2558 		else if (!(sci->sc_flush_request & ~FLUSH_DAT_BIT))
2559 			return SC_FLUSH_DAT;
2560 	}
2561 	return SC_LSEG_SR;
2562 }
2563 
2564 /**
2565  * nilfs_segctor_thread - main loop of the segment constructor thread.
2566  * @arg: pointer to a struct nilfs_sc_info.
2567  *
2568  * nilfs_segctor_thread() initializes a timer and serves as a daemon
2569  * to execute segment constructions.
2570  */
2571 static int nilfs_segctor_thread(void *arg)
2572 {
2573 	struct nilfs_sc_info *sci = (struct nilfs_sc_info *)arg;
2574 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2575 	int timeout = 0;
2576 
2577 	sci->sc_timer_task = current;
2578 
2579 	/* start sync. */
2580 	sci->sc_task = current;
2581 	wake_up(&sci->sc_wait_task); /* for nilfs_segctor_start_thread() */
2582 	nilfs_info(sci->sc_super,
2583 		   "segctord starting. Construction interval = %lu seconds, CP frequency < %lu seconds",
2584 		   sci->sc_interval / HZ, sci->sc_mjcp_freq / HZ);
2585 
2586 	spin_lock(&sci->sc_state_lock);
2587  loop:
2588 	for (;;) {
2589 		int mode;
2590 
2591 		if (sci->sc_state & NILFS_SEGCTOR_QUIT)
2592 			goto end_thread;
2593 
2594 		if (timeout || sci->sc_seq_request != sci->sc_seq_done)
2595 			mode = SC_LSEG_SR;
2596 		else if (sci->sc_flush_request)
2597 			mode = nilfs_segctor_flush_mode(sci);
2598 		else
2599 			break;
2600 
2601 		spin_unlock(&sci->sc_state_lock);
2602 		nilfs_segctor_thread_construct(sci, mode);
2603 		spin_lock(&sci->sc_state_lock);
2604 		timeout = 0;
2605 	}
2606 
2607 
2608 	if (freezing(current)) {
2609 		spin_unlock(&sci->sc_state_lock);
2610 		try_to_freeze();
2611 		spin_lock(&sci->sc_state_lock);
2612 	} else {
2613 		DEFINE_WAIT(wait);
2614 		int should_sleep = 1;
2615 
2616 		prepare_to_wait(&sci->sc_wait_daemon, &wait,
2617 				TASK_INTERRUPTIBLE);
2618 
2619 		if (sci->sc_seq_request != sci->sc_seq_done)
2620 			should_sleep = 0;
2621 		else if (sci->sc_flush_request)
2622 			should_sleep = 0;
2623 		else if (sci->sc_state & NILFS_SEGCTOR_COMMIT)
2624 			should_sleep = time_before(jiffies,
2625 					sci->sc_timer.expires);
2626 
2627 		if (should_sleep) {
2628 			spin_unlock(&sci->sc_state_lock);
2629 			schedule();
2630 			spin_lock(&sci->sc_state_lock);
2631 		}
2632 		finish_wait(&sci->sc_wait_daemon, &wait);
2633 		timeout = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
2634 			   time_after_eq(jiffies, sci->sc_timer.expires));
2635 
2636 		if (nilfs_sb_dirty(nilfs) && nilfs_sb_need_update(nilfs))
2637 			set_nilfs_discontinued(nilfs);
2638 	}
2639 	goto loop;
2640 
2641  end_thread:
2642 	/* end sync. */
2643 	sci->sc_task = NULL;
2644 	wake_up(&sci->sc_wait_task); /* for nilfs_segctor_kill_thread() */
2645 	spin_unlock(&sci->sc_state_lock);
2646 	return 0;
2647 }
2648 
2649 static int nilfs_segctor_start_thread(struct nilfs_sc_info *sci)
2650 {
2651 	struct task_struct *t;
2652 
2653 	t = kthread_run(nilfs_segctor_thread, sci, "segctord");
2654 	if (IS_ERR(t)) {
2655 		int err = PTR_ERR(t);
2656 
2657 		nilfs_err(sci->sc_super, "error %d creating segctord thread",
2658 			  err);
2659 		return err;
2660 	}
2661 	wait_event(sci->sc_wait_task, sci->sc_task != NULL);
2662 	return 0;
2663 }
2664 
2665 static void nilfs_segctor_kill_thread(struct nilfs_sc_info *sci)
2666 	__acquires(&sci->sc_state_lock)
2667 	__releases(&sci->sc_state_lock)
2668 {
2669 	sci->sc_state |= NILFS_SEGCTOR_QUIT;
2670 
2671 	while (sci->sc_task) {
2672 		wake_up(&sci->sc_wait_daemon);
2673 		spin_unlock(&sci->sc_state_lock);
2674 		wait_event(sci->sc_wait_task, sci->sc_task == NULL);
2675 		spin_lock(&sci->sc_state_lock);
2676 	}
2677 }
2678 
2679 /*
2680  * Setup & clean-up functions
2681  */
2682 static struct nilfs_sc_info *nilfs_segctor_new(struct super_block *sb,
2683 					       struct nilfs_root *root)
2684 {
2685 	struct the_nilfs *nilfs = sb->s_fs_info;
2686 	struct nilfs_sc_info *sci;
2687 
2688 	sci = kzalloc(sizeof(*sci), GFP_KERNEL);
2689 	if (!sci)
2690 		return NULL;
2691 
2692 	sci->sc_super = sb;
2693 
2694 	nilfs_get_root(root);
2695 	sci->sc_root = root;
2696 
2697 	init_waitqueue_head(&sci->sc_wait_request);
2698 	init_waitqueue_head(&sci->sc_wait_daemon);
2699 	init_waitqueue_head(&sci->sc_wait_task);
2700 	spin_lock_init(&sci->sc_state_lock);
2701 	INIT_LIST_HEAD(&sci->sc_dirty_files);
2702 	INIT_LIST_HEAD(&sci->sc_segbufs);
2703 	INIT_LIST_HEAD(&sci->sc_write_logs);
2704 	INIT_LIST_HEAD(&sci->sc_gc_inodes);
2705 	INIT_LIST_HEAD(&sci->sc_iput_queue);
2706 	INIT_WORK(&sci->sc_iput_work, nilfs_iput_work_func);
2707 	timer_setup(&sci->sc_timer, nilfs_construction_timeout, 0);
2708 
2709 	sci->sc_interval = HZ * NILFS_SC_DEFAULT_TIMEOUT;
2710 	sci->sc_mjcp_freq = HZ * NILFS_SC_DEFAULT_SR_FREQ;
2711 	sci->sc_watermark = NILFS_SC_DEFAULT_WATERMARK;
2712 
2713 	if (nilfs->ns_interval)
2714 		sci->sc_interval = HZ * nilfs->ns_interval;
2715 	if (nilfs->ns_watermark)
2716 		sci->sc_watermark = nilfs->ns_watermark;
2717 	return sci;
2718 }
2719 
2720 static void nilfs_segctor_write_out(struct nilfs_sc_info *sci)
2721 {
2722 	int ret, retrycount = NILFS_SC_CLEANUP_RETRY;
2723 
2724 	/*
2725 	 * The segctord thread was stopped and its timer was removed.
2726 	 * But some tasks remain.
2727 	 */
2728 	do {
2729 		struct nilfs_transaction_info ti;
2730 
2731 		nilfs_transaction_lock(sci->sc_super, &ti, 0);
2732 		ret = nilfs_segctor_construct(sci, SC_LSEG_SR);
2733 		nilfs_transaction_unlock(sci->sc_super);
2734 
2735 		flush_work(&sci->sc_iput_work);
2736 
2737 	} while (ret && ret != -EROFS && retrycount-- > 0);
2738 }
2739 
2740 /**
2741  * nilfs_segctor_destroy - destroy the segment constructor.
2742  * @sci: nilfs_sc_info
2743  *
2744  * nilfs_segctor_destroy() kills the segctord thread and frees
2745  * the nilfs_sc_info struct.
2746  * Caller must hold the segment semaphore.
2747  */
2748 static void nilfs_segctor_destroy(struct nilfs_sc_info *sci)
2749 {
2750 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2751 	int flag;
2752 
2753 	up_write(&nilfs->ns_segctor_sem);
2754 
2755 	spin_lock(&sci->sc_state_lock);
2756 	nilfs_segctor_kill_thread(sci);
2757 	flag = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) || sci->sc_flush_request
2758 		|| sci->sc_seq_request != sci->sc_seq_done);
2759 	spin_unlock(&sci->sc_state_lock);
2760 
2761 	if (flush_work(&sci->sc_iput_work))
2762 		flag = true;
2763 
2764 	if (flag || !nilfs_segctor_confirm(sci))
2765 		nilfs_segctor_write_out(sci);
2766 
2767 	if (!list_empty(&sci->sc_dirty_files)) {
2768 		nilfs_warn(sci->sc_super,
2769 			   "disposed unprocessed dirty file(s) when stopping log writer");
2770 		nilfs_dispose_list(nilfs, &sci->sc_dirty_files, 1);
2771 	}
2772 
2773 	if (!list_empty(&sci->sc_iput_queue)) {
2774 		nilfs_warn(sci->sc_super,
2775 			   "disposed unprocessed inode(s) in iput queue when stopping log writer");
2776 		nilfs_dispose_list(nilfs, &sci->sc_iput_queue, 1);
2777 	}
2778 
2779 	WARN_ON(!list_empty(&sci->sc_segbufs));
2780 	WARN_ON(!list_empty(&sci->sc_write_logs));
2781 
2782 	nilfs_put_root(sci->sc_root);
2783 
2784 	down_write(&nilfs->ns_segctor_sem);
2785 
2786 	timer_shutdown_sync(&sci->sc_timer);
2787 	kfree(sci);
2788 }
2789 
2790 /**
2791  * nilfs_attach_log_writer - attach log writer
2792  * @sb: super block instance
2793  * @root: root object of the current filesystem tree
2794  *
2795  * This allocates a log writer object, initializes it, and starts the
2796  * log writer.
2797  *
2798  * Return Value: On success, 0 is returned. On error, one of the following
2799  * negative error code is returned.
2800  *
2801  * %-ENOMEM - Insufficient memory available.
2802  */
2803 int nilfs_attach_log_writer(struct super_block *sb, struct nilfs_root *root)
2804 {
2805 	struct the_nilfs *nilfs = sb->s_fs_info;
2806 	int err;
2807 
2808 	if (nilfs->ns_writer) {
2809 		/*
2810 		 * This happens if the filesystem is made read-only by
2811 		 * __nilfs_error or nilfs_remount and then remounted
2812 		 * read/write.  In these cases, reuse the existing
2813 		 * writer.
2814 		 */
2815 		return 0;
2816 	}
2817 
2818 	nilfs->ns_writer = nilfs_segctor_new(sb, root);
2819 	if (!nilfs->ns_writer)
2820 		return -ENOMEM;
2821 
2822 	inode_attach_wb(nilfs->ns_bdev->bd_inode, NULL);
2823 
2824 	err = nilfs_segctor_start_thread(nilfs->ns_writer);
2825 	if (unlikely(err))
2826 		nilfs_detach_log_writer(sb);
2827 
2828 	return err;
2829 }
2830 
2831 /**
2832  * nilfs_detach_log_writer - destroy log writer
2833  * @sb: super block instance
2834  *
2835  * This kills log writer daemon, frees the log writer object, and
2836  * destroys list of dirty files.
2837  */
2838 void nilfs_detach_log_writer(struct super_block *sb)
2839 {
2840 	struct the_nilfs *nilfs = sb->s_fs_info;
2841 	LIST_HEAD(garbage_list);
2842 
2843 	down_write(&nilfs->ns_segctor_sem);
2844 	if (nilfs->ns_writer) {
2845 		nilfs_segctor_destroy(nilfs->ns_writer);
2846 		nilfs->ns_writer = NULL;
2847 	}
2848 
2849 	/* Force to free the list of dirty files */
2850 	spin_lock(&nilfs->ns_inode_lock);
2851 	if (!list_empty(&nilfs->ns_dirty_files)) {
2852 		list_splice_init(&nilfs->ns_dirty_files, &garbage_list);
2853 		nilfs_warn(sb,
2854 			   "disposed unprocessed dirty file(s) when detaching log writer");
2855 	}
2856 	spin_unlock(&nilfs->ns_inode_lock);
2857 	up_write(&nilfs->ns_segctor_sem);
2858 
2859 	nilfs_dispose_list(nilfs, &garbage_list, 1);
2860 }
2861