xref: /openbmc/linux/fs/nilfs2/segment.c (revision be2b81b5)
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 static int nilfs_segctor_feed_segment(struct nilfs_sc_info *sci)
434 {
435 	sci->sc_nblk_this_inc += sci->sc_curseg->sb_sum.nblocks;
436 	if (NILFS_SEGBUF_IS_LAST(sci->sc_curseg, &sci->sc_segbufs))
437 		return -E2BIG; /*
438 				* The current segment is filled up
439 				* (internal code)
440 				*/
441 	sci->sc_curseg = NILFS_NEXT_SEGBUF(sci->sc_curseg);
442 	return nilfs_segctor_reset_segment_buffer(sci);
443 }
444 
445 static int nilfs_segctor_add_super_root(struct nilfs_sc_info *sci)
446 {
447 	struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
448 	int err;
449 
450 	if (segbuf->sb_sum.nblocks >= segbuf->sb_rest_blocks) {
451 		err = nilfs_segctor_feed_segment(sci);
452 		if (err)
453 			return err;
454 		segbuf = sci->sc_curseg;
455 	}
456 	err = nilfs_segbuf_extend_payload(segbuf, &segbuf->sb_super_root);
457 	if (likely(!err))
458 		segbuf->sb_sum.flags |= NILFS_SS_SR;
459 	return err;
460 }
461 
462 /*
463  * Functions for making segment summary and payloads
464  */
465 static int nilfs_segctor_segsum_block_required(
466 	struct nilfs_sc_info *sci, const struct nilfs_segsum_pointer *ssp,
467 	unsigned int binfo_size)
468 {
469 	unsigned int blocksize = sci->sc_super->s_blocksize;
470 	/* Size of finfo and binfo is enough small against blocksize */
471 
472 	return ssp->offset + binfo_size +
473 		(!sci->sc_blk_cnt ? sizeof(struct nilfs_finfo) : 0) >
474 		blocksize;
475 }
476 
477 static void nilfs_segctor_begin_finfo(struct nilfs_sc_info *sci,
478 				      struct inode *inode)
479 {
480 	sci->sc_curseg->sb_sum.nfinfo++;
481 	sci->sc_binfo_ptr = sci->sc_finfo_ptr;
482 	nilfs_segctor_map_segsum_entry(
483 		sci, &sci->sc_binfo_ptr, sizeof(struct nilfs_finfo));
484 
485 	if (NILFS_I(inode)->i_root &&
486 	    !test_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags))
487 		set_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
488 	/* skip finfo */
489 }
490 
491 static void nilfs_segctor_end_finfo(struct nilfs_sc_info *sci,
492 				    struct inode *inode)
493 {
494 	struct nilfs_finfo *finfo;
495 	struct nilfs_inode_info *ii;
496 	struct nilfs_segment_buffer *segbuf;
497 	__u64 cno;
498 
499 	if (sci->sc_blk_cnt == 0)
500 		return;
501 
502 	ii = NILFS_I(inode);
503 
504 	if (test_bit(NILFS_I_GCINODE, &ii->i_state))
505 		cno = ii->i_cno;
506 	else if (NILFS_ROOT_METADATA_FILE(inode->i_ino))
507 		cno = 0;
508 	else
509 		cno = sci->sc_cno;
510 
511 	finfo = nilfs_segctor_map_segsum_entry(sci, &sci->sc_finfo_ptr,
512 						 sizeof(*finfo));
513 	finfo->fi_ino = cpu_to_le64(inode->i_ino);
514 	finfo->fi_nblocks = cpu_to_le32(sci->sc_blk_cnt);
515 	finfo->fi_ndatablk = cpu_to_le32(sci->sc_datablk_cnt);
516 	finfo->fi_cno = cpu_to_le64(cno);
517 
518 	segbuf = sci->sc_curseg;
519 	segbuf->sb_sum.sumbytes = sci->sc_binfo_ptr.offset +
520 		sci->sc_super->s_blocksize * (segbuf->sb_sum.nsumblk - 1);
521 	sci->sc_finfo_ptr = sci->sc_binfo_ptr;
522 	sci->sc_blk_cnt = sci->sc_datablk_cnt = 0;
523 }
524 
525 static int nilfs_segctor_add_file_block(struct nilfs_sc_info *sci,
526 					struct buffer_head *bh,
527 					struct inode *inode,
528 					unsigned int binfo_size)
529 {
530 	struct nilfs_segment_buffer *segbuf;
531 	int required, err = 0;
532 
533  retry:
534 	segbuf = sci->sc_curseg;
535 	required = nilfs_segctor_segsum_block_required(
536 		sci, &sci->sc_binfo_ptr, binfo_size);
537 	if (segbuf->sb_sum.nblocks + required + 1 > segbuf->sb_rest_blocks) {
538 		nilfs_segctor_end_finfo(sci, inode);
539 		err = nilfs_segctor_feed_segment(sci);
540 		if (err)
541 			return err;
542 		goto retry;
543 	}
544 	if (unlikely(required)) {
545 		err = nilfs_segbuf_extend_segsum(segbuf);
546 		if (unlikely(err))
547 			goto failed;
548 	}
549 	if (sci->sc_blk_cnt == 0)
550 		nilfs_segctor_begin_finfo(sci, inode);
551 
552 	nilfs_segctor_map_segsum_entry(sci, &sci->sc_binfo_ptr, binfo_size);
553 	/* Substitution to vblocknr is delayed until update_blocknr() */
554 	nilfs_segbuf_add_file_buffer(segbuf, bh);
555 	sci->sc_blk_cnt++;
556  failed:
557 	return err;
558 }
559 
560 /*
561  * Callback functions that enumerate, mark, and collect dirty blocks
562  */
563 static int nilfs_collect_file_data(struct nilfs_sc_info *sci,
564 				   struct buffer_head *bh, struct inode *inode)
565 {
566 	int err;
567 
568 	err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
569 	if (err < 0)
570 		return err;
571 
572 	err = nilfs_segctor_add_file_block(sci, bh, inode,
573 					   sizeof(struct nilfs_binfo_v));
574 	if (!err)
575 		sci->sc_datablk_cnt++;
576 	return err;
577 }
578 
579 static int nilfs_collect_file_node(struct nilfs_sc_info *sci,
580 				   struct buffer_head *bh,
581 				   struct inode *inode)
582 {
583 	return nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
584 }
585 
586 static int nilfs_collect_file_bmap(struct nilfs_sc_info *sci,
587 				   struct buffer_head *bh,
588 				   struct inode *inode)
589 {
590 	WARN_ON(!buffer_dirty(bh));
591 	return nilfs_segctor_add_file_block(sci, bh, inode, sizeof(__le64));
592 }
593 
594 static void nilfs_write_file_data_binfo(struct nilfs_sc_info *sci,
595 					struct nilfs_segsum_pointer *ssp,
596 					union nilfs_binfo *binfo)
597 {
598 	struct nilfs_binfo_v *binfo_v = nilfs_segctor_map_segsum_entry(
599 		sci, ssp, sizeof(*binfo_v));
600 	*binfo_v = binfo->bi_v;
601 }
602 
603 static void nilfs_write_file_node_binfo(struct nilfs_sc_info *sci,
604 					struct nilfs_segsum_pointer *ssp,
605 					union nilfs_binfo *binfo)
606 {
607 	__le64 *vblocknr = nilfs_segctor_map_segsum_entry(
608 		sci, ssp, sizeof(*vblocknr));
609 	*vblocknr = binfo->bi_v.bi_vblocknr;
610 }
611 
612 static const struct nilfs_sc_operations nilfs_sc_file_ops = {
613 	.collect_data = nilfs_collect_file_data,
614 	.collect_node = nilfs_collect_file_node,
615 	.collect_bmap = nilfs_collect_file_bmap,
616 	.write_data_binfo = nilfs_write_file_data_binfo,
617 	.write_node_binfo = nilfs_write_file_node_binfo,
618 };
619 
620 static int nilfs_collect_dat_data(struct nilfs_sc_info *sci,
621 				  struct buffer_head *bh, struct inode *inode)
622 {
623 	int err;
624 
625 	err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
626 	if (err < 0)
627 		return err;
628 
629 	err = nilfs_segctor_add_file_block(sci, bh, inode, sizeof(__le64));
630 	if (!err)
631 		sci->sc_datablk_cnt++;
632 	return err;
633 }
634 
635 static int nilfs_collect_dat_bmap(struct nilfs_sc_info *sci,
636 				  struct buffer_head *bh, struct inode *inode)
637 {
638 	WARN_ON(!buffer_dirty(bh));
639 	return nilfs_segctor_add_file_block(sci, bh, inode,
640 					    sizeof(struct nilfs_binfo_dat));
641 }
642 
643 static void nilfs_write_dat_data_binfo(struct nilfs_sc_info *sci,
644 				       struct nilfs_segsum_pointer *ssp,
645 				       union nilfs_binfo *binfo)
646 {
647 	__le64 *blkoff = nilfs_segctor_map_segsum_entry(sci, ssp,
648 							  sizeof(*blkoff));
649 	*blkoff = binfo->bi_dat.bi_blkoff;
650 }
651 
652 static void nilfs_write_dat_node_binfo(struct nilfs_sc_info *sci,
653 				       struct nilfs_segsum_pointer *ssp,
654 				       union nilfs_binfo *binfo)
655 {
656 	struct nilfs_binfo_dat *binfo_dat =
657 		nilfs_segctor_map_segsum_entry(sci, ssp, sizeof(*binfo_dat));
658 	*binfo_dat = binfo->bi_dat;
659 }
660 
661 static const struct nilfs_sc_operations nilfs_sc_dat_ops = {
662 	.collect_data = nilfs_collect_dat_data,
663 	.collect_node = nilfs_collect_file_node,
664 	.collect_bmap = nilfs_collect_dat_bmap,
665 	.write_data_binfo = nilfs_write_dat_data_binfo,
666 	.write_node_binfo = nilfs_write_dat_node_binfo,
667 };
668 
669 static const struct nilfs_sc_operations nilfs_sc_dsync_ops = {
670 	.collect_data = nilfs_collect_file_data,
671 	.collect_node = NULL,
672 	.collect_bmap = NULL,
673 	.write_data_binfo = nilfs_write_file_data_binfo,
674 	.write_node_binfo = NULL,
675 };
676 
677 static size_t nilfs_lookup_dirty_data_buffers(struct inode *inode,
678 					      struct list_head *listp,
679 					      size_t nlimit,
680 					      loff_t start, loff_t end)
681 {
682 	struct address_space *mapping = inode->i_mapping;
683 	struct pagevec pvec;
684 	pgoff_t index = 0, last = ULONG_MAX;
685 	size_t ndirties = 0;
686 	int i;
687 
688 	if (unlikely(start != 0 || end != LLONG_MAX)) {
689 		/*
690 		 * A valid range is given for sync-ing data pages. The
691 		 * range is rounded to per-page; extra dirty buffers
692 		 * may be included if blocksize < pagesize.
693 		 */
694 		index = start >> PAGE_SHIFT;
695 		last = end >> PAGE_SHIFT;
696 	}
697 	pagevec_init(&pvec);
698  repeat:
699 	if (unlikely(index > last) ||
700 	    !pagevec_lookup_range_tag(&pvec, mapping, &index, last,
701 				PAGECACHE_TAG_DIRTY))
702 		return ndirties;
703 
704 	for (i = 0; i < pagevec_count(&pvec); i++) {
705 		struct buffer_head *bh, *head;
706 		struct page *page = pvec.pages[i];
707 
708 		lock_page(page);
709 		if (!page_has_buffers(page))
710 			create_empty_buffers(page, i_blocksize(inode), 0);
711 		unlock_page(page);
712 
713 		bh = head = page_buffers(page);
714 		do {
715 			if (!buffer_dirty(bh) || buffer_async_write(bh))
716 				continue;
717 			get_bh(bh);
718 			list_add_tail(&bh->b_assoc_buffers, listp);
719 			ndirties++;
720 			if (unlikely(ndirties >= nlimit)) {
721 				pagevec_release(&pvec);
722 				cond_resched();
723 				return ndirties;
724 			}
725 		} while (bh = bh->b_this_page, bh != head);
726 	}
727 	pagevec_release(&pvec);
728 	cond_resched();
729 	goto repeat;
730 }
731 
732 static void nilfs_lookup_dirty_node_buffers(struct inode *inode,
733 					    struct list_head *listp)
734 {
735 	struct nilfs_inode_info *ii = NILFS_I(inode);
736 	struct inode *btnc_inode = ii->i_assoc_inode;
737 	struct pagevec pvec;
738 	struct buffer_head *bh, *head;
739 	unsigned int i;
740 	pgoff_t index = 0;
741 
742 	if (!btnc_inode)
743 		return;
744 
745 	pagevec_init(&pvec);
746 
747 	while (pagevec_lookup_tag(&pvec, btnc_inode->i_mapping, &index,
748 					PAGECACHE_TAG_DIRTY)) {
749 		for (i = 0; i < pagevec_count(&pvec); i++) {
750 			bh = head = page_buffers(pvec.pages[i]);
751 			do {
752 				if (buffer_dirty(bh) &&
753 						!buffer_async_write(bh)) {
754 					get_bh(bh);
755 					list_add_tail(&bh->b_assoc_buffers,
756 						      listp);
757 				}
758 				bh = bh->b_this_page;
759 			} while (bh != head);
760 		}
761 		pagevec_release(&pvec);
762 		cond_resched();
763 	}
764 }
765 
766 static void nilfs_dispose_list(struct the_nilfs *nilfs,
767 			       struct list_head *head, int force)
768 {
769 	struct nilfs_inode_info *ii, *n;
770 	struct nilfs_inode_info *ivec[SC_N_INODEVEC], **pii;
771 	unsigned int nv = 0;
772 
773 	while (!list_empty(head)) {
774 		spin_lock(&nilfs->ns_inode_lock);
775 		list_for_each_entry_safe(ii, n, head, i_dirty) {
776 			list_del_init(&ii->i_dirty);
777 			if (force) {
778 				if (unlikely(ii->i_bh)) {
779 					brelse(ii->i_bh);
780 					ii->i_bh = NULL;
781 				}
782 			} else if (test_bit(NILFS_I_DIRTY, &ii->i_state)) {
783 				set_bit(NILFS_I_QUEUED, &ii->i_state);
784 				list_add_tail(&ii->i_dirty,
785 					      &nilfs->ns_dirty_files);
786 				continue;
787 			}
788 			ivec[nv++] = ii;
789 			if (nv == SC_N_INODEVEC)
790 				break;
791 		}
792 		spin_unlock(&nilfs->ns_inode_lock);
793 
794 		for (pii = ivec; nv > 0; pii++, nv--)
795 			iput(&(*pii)->vfs_inode);
796 	}
797 }
798 
799 static void nilfs_iput_work_func(struct work_struct *work)
800 {
801 	struct nilfs_sc_info *sci = container_of(work, struct nilfs_sc_info,
802 						 sc_iput_work);
803 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
804 
805 	nilfs_dispose_list(nilfs, &sci->sc_iput_queue, 0);
806 }
807 
808 static int nilfs_test_metadata_dirty(struct the_nilfs *nilfs,
809 				     struct nilfs_root *root)
810 {
811 	int ret = 0;
812 
813 	if (nilfs_mdt_fetch_dirty(root->ifile))
814 		ret++;
815 	if (nilfs_mdt_fetch_dirty(nilfs->ns_cpfile))
816 		ret++;
817 	if (nilfs_mdt_fetch_dirty(nilfs->ns_sufile))
818 		ret++;
819 	if ((ret || nilfs_doing_gc()) && nilfs_mdt_fetch_dirty(nilfs->ns_dat))
820 		ret++;
821 	return ret;
822 }
823 
824 static int nilfs_segctor_clean(struct nilfs_sc_info *sci)
825 {
826 	return list_empty(&sci->sc_dirty_files) &&
827 		!test_bit(NILFS_SC_DIRTY, &sci->sc_flags) &&
828 		sci->sc_nfreesegs == 0 &&
829 		(!nilfs_doing_gc() || list_empty(&sci->sc_gc_inodes));
830 }
831 
832 static int nilfs_segctor_confirm(struct nilfs_sc_info *sci)
833 {
834 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
835 	int ret = 0;
836 
837 	if (nilfs_test_metadata_dirty(nilfs, sci->sc_root))
838 		set_bit(NILFS_SC_DIRTY, &sci->sc_flags);
839 
840 	spin_lock(&nilfs->ns_inode_lock);
841 	if (list_empty(&nilfs->ns_dirty_files) && nilfs_segctor_clean(sci))
842 		ret++;
843 
844 	spin_unlock(&nilfs->ns_inode_lock);
845 	return ret;
846 }
847 
848 static void nilfs_segctor_clear_metadata_dirty(struct nilfs_sc_info *sci)
849 {
850 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
851 
852 	nilfs_mdt_clear_dirty(sci->sc_root->ifile);
853 	nilfs_mdt_clear_dirty(nilfs->ns_cpfile);
854 	nilfs_mdt_clear_dirty(nilfs->ns_sufile);
855 	nilfs_mdt_clear_dirty(nilfs->ns_dat);
856 }
857 
858 static int nilfs_segctor_create_checkpoint(struct nilfs_sc_info *sci)
859 {
860 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
861 	struct buffer_head *bh_cp;
862 	struct nilfs_checkpoint *raw_cp;
863 	int err;
864 
865 	/* XXX: this interface will be changed */
866 	err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, 1,
867 					  &raw_cp, &bh_cp);
868 	if (likely(!err)) {
869 		/*
870 		 * The following code is duplicated with cpfile.  But, it is
871 		 * needed to collect the checkpoint even if it was not newly
872 		 * created.
873 		 */
874 		mark_buffer_dirty(bh_cp);
875 		nilfs_mdt_mark_dirty(nilfs->ns_cpfile);
876 		nilfs_cpfile_put_checkpoint(
877 			nilfs->ns_cpfile, nilfs->ns_cno, bh_cp);
878 	} else if (err == -EINVAL || err == -ENOENT) {
879 		nilfs_error(sci->sc_super,
880 			    "checkpoint creation failed due to metadata corruption.");
881 		err = -EIO;
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 		if (err == -EINVAL || err == -ENOENT) {
897 			nilfs_error(sci->sc_super,
898 				    "checkpoint finalization failed due to metadata corruption.");
899 			err = -EIO;
900 		}
901 		goto failed_ibh;
902 	}
903 	raw_cp->cp_snapshot_list.ssl_next = 0;
904 	raw_cp->cp_snapshot_list.ssl_prev = 0;
905 	raw_cp->cp_inodes_count =
906 		cpu_to_le64(atomic64_read(&sci->sc_root->inodes_count));
907 	raw_cp->cp_blocks_count =
908 		cpu_to_le64(atomic64_read(&sci->sc_root->blocks_count));
909 	raw_cp->cp_nblk_inc =
910 		cpu_to_le64(sci->sc_nblk_inc + sci->sc_nblk_this_inc);
911 	raw_cp->cp_create = cpu_to_le64(sci->sc_seg_ctime);
912 	raw_cp->cp_cno = cpu_to_le64(nilfs->ns_cno);
913 
914 	if (test_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags))
915 		nilfs_checkpoint_clear_minor(raw_cp);
916 	else
917 		nilfs_checkpoint_set_minor(raw_cp);
918 
919 	nilfs_write_inode_common(sci->sc_root->ifile,
920 				 &raw_cp->cp_ifile_inode, 1);
921 	nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, bh_cp);
922 	return 0;
923 
924  failed_ibh:
925 	return err;
926 }
927 
928 static void nilfs_fill_in_file_bmap(struct inode *ifile,
929 				    struct nilfs_inode_info *ii)
930 
931 {
932 	struct buffer_head *ibh;
933 	struct nilfs_inode *raw_inode;
934 
935 	if (test_bit(NILFS_I_BMAP, &ii->i_state)) {
936 		ibh = ii->i_bh;
937 		BUG_ON(!ibh);
938 		raw_inode = nilfs_ifile_map_inode(ifile, ii->vfs_inode.i_ino,
939 						  ibh);
940 		nilfs_bmap_write(ii->i_bmap, raw_inode);
941 		nilfs_ifile_unmap_inode(ifile, ii->vfs_inode.i_ino, ibh);
942 	}
943 }
944 
945 static void nilfs_segctor_fill_in_file_bmap(struct nilfs_sc_info *sci)
946 {
947 	struct nilfs_inode_info *ii;
948 
949 	list_for_each_entry(ii, &sci->sc_dirty_files, i_dirty) {
950 		nilfs_fill_in_file_bmap(sci->sc_root->ifile, ii);
951 		set_bit(NILFS_I_COLLECTED, &ii->i_state);
952 	}
953 }
954 
955 static void nilfs_segctor_fill_in_super_root(struct nilfs_sc_info *sci,
956 					     struct the_nilfs *nilfs)
957 {
958 	struct buffer_head *bh_sr;
959 	struct nilfs_super_root *raw_sr;
960 	unsigned int isz, srsz;
961 
962 	bh_sr = NILFS_LAST_SEGBUF(&sci->sc_segbufs)->sb_super_root;
963 	raw_sr = (struct nilfs_super_root *)bh_sr->b_data;
964 	isz = nilfs->ns_inode_size;
965 	srsz = NILFS_SR_BYTES(isz);
966 
967 	raw_sr->sr_bytes = cpu_to_le16(srsz);
968 	raw_sr->sr_nongc_ctime
969 		= cpu_to_le64(nilfs_doing_gc() ?
970 			      nilfs->ns_nongc_ctime : sci->sc_seg_ctime);
971 	raw_sr->sr_flags = 0;
972 
973 	nilfs_write_inode_common(nilfs->ns_dat, (void *)raw_sr +
974 				 NILFS_SR_DAT_OFFSET(isz), 1);
975 	nilfs_write_inode_common(nilfs->ns_cpfile, (void *)raw_sr +
976 				 NILFS_SR_CPFILE_OFFSET(isz), 1);
977 	nilfs_write_inode_common(nilfs->ns_sufile, (void *)raw_sr +
978 				 NILFS_SR_SUFILE_OFFSET(isz), 1);
979 	memset((void *)raw_sr + srsz, 0, nilfs->ns_blocksize - srsz);
980 }
981 
982 static void nilfs_redirty_inodes(struct list_head *head)
983 {
984 	struct nilfs_inode_info *ii;
985 
986 	list_for_each_entry(ii, head, i_dirty) {
987 		if (test_bit(NILFS_I_COLLECTED, &ii->i_state))
988 			clear_bit(NILFS_I_COLLECTED, &ii->i_state);
989 	}
990 }
991 
992 static void nilfs_drop_collected_inodes(struct list_head *head)
993 {
994 	struct nilfs_inode_info *ii;
995 
996 	list_for_each_entry(ii, head, i_dirty) {
997 		if (!test_and_clear_bit(NILFS_I_COLLECTED, &ii->i_state))
998 			continue;
999 
1000 		clear_bit(NILFS_I_INODE_SYNC, &ii->i_state);
1001 		set_bit(NILFS_I_UPDATED, &ii->i_state);
1002 	}
1003 }
1004 
1005 static int nilfs_segctor_apply_buffers(struct nilfs_sc_info *sci,
1006 				       struct inode *inode,
1007 				       struct list_head *listp,
1008 				       int (*collect)(struct nilfs_sc_info *,
1009 						      struct buffer_head *,
1010 						      struct inode *))
1011 {
1012 	struct buffer_head *bh, *n;
1013 	int err = 0;
1014 
1015 	if (collect) {
1016 		list_for_each_entry_safe(bh, n, listp, b_assoc_buffers) {
1017 			list_del_init(&bh->b_assoc_buffers);
1018 			err = collect(sci, bh, inode);
1019 			brelse(bh);
1020 			if (unlikely(err))
1021 				goto dispose_buffers;
1022 		}
1023 		return 0;
1024 	}
1025 
1026  dispose_buffers:
1027 	while (!list_empty(listp)) {
1028 		bh = list_first_entry(listp, struct buffer_head,
1029 				      b_assoc_buffers);
1030 		list_del_init(&bh->b_assoc_buffers);
1031 		brelse(bh);
1032 	}
1033 	return err;
1034 }
1035 
1036 static size_t nilfs_segctor_buffer_rest(struct nilfs_sc_info *sci)
1037 {
1038 	/* Remaining number of blocks within segment buffer */
1039 	return sci->sc_segbuf_nblocks -
1040 		(sci->sc_nblk_this_inc + sci->sc_curseg->sb_sum.nblocks);
1041 }
1042 
1043 static int nilfs_segctor_scan_file(struct nilfs_sc_info *sci,
1044 				   struct inode *inode,
1045 				   const struct nilfs_sc_operations *sc_ops)
1046 {
1047 	LIST_HEAD(data_buffers);
1048 	LIST_HEAD(node_buffers);
1049 	int err;
1050 
1051 	if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
1052 		size_t n, rest = nilfs_segctor_buffer_rest(sci);
1053 
1054 		n = nilfs_lookup_dirty_data_buffers(
1055 			inode, &data_buffers, rest + 1, 0, LLONG_MAX);
1056 		if (n > rest) {
1057 			err = nilfs_segctor_apply_buffers(
1058 				sci, inode, &data_buffers,
1059 				sc_ops->collect_data);
1060 			BUG_ON(!err); /* always receive -E2BIG or true error */
1061 			goto break_or_fail;
1062 		}
1063 	}
1064 	nilfs_lookup_dirty_node_buffers(inode, &node_buffers);
1065 
1066 	if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
1067 		err = nilfs_segctor_apply_buffers(
1068 			sci, inode, &data_buffers, sc_ops->collect_data);
1069 		if (unlikely(err)) {
1070 			/* dispose node list */
1071 			nilfs_segctor_apply_buffers(
1072 				sci, inode, &node_buffers, NULL);
1073 			goto break_or_fail;
1074 		}
1075 		sci->sc_stage.flags |= NILFS_CF_NODE;
1076 	}
1077 	/* Collect node */
1078 	err = nilfs_segctor_apply_buffers(
1079 		sci, inode, &node_buffers, sc_ops->collect_node);
1080 	if (unlikely(err))
1081 		goto break_or_fail;
1082 
1083 	nilfs_bmap_lookup_dirty_buffers(NILFS_I(inode)->i_bmap, &node_buffers);
1084 	err = nilfs_segctor_apply_buffers(
1085 		sci, inode, &node_buffers, sc_ops->collect_bmap);
1086 	if (unlikely(err))
1087 		goto break_or_fail;
1088 
1089 	nilfs_segctor_end_finfo(sci, inode);
1090 	sci->sc_stage.flags &= ~NILFS_CF_NODE;
1091 
1092  break_or_fail:
1093 	return err;
1094 }
1095 
1096 static int nilfs_segctor_scan_file_dsync(struct nilfs_sc_info *sci,
1097 					 struct inode *inode)
1098 {
1099 	LIST_HEAD(data_buffers);
1100 	size_t n, rest = nilfs_segctor_buffer_rest(sci);
1101 	int err;
1102 
1103 	n = nilfs_lookup_dirty_data_buffers(inode, &data_buffers, rest + 1,
1104 					    sci->sc_dsync_start,
1105 					    sci->sc_dsync_end);
1106 
1107 	err = nilfs_segctor_apply_buffers(sci, inode, &data_buffers,
1108 					  nilfs_collect_file_data);
1109 	if (!err) {
1110 		nilfs_segctor_end_finfo(sci, inode);
1111 		BUG_ON(n > rest);
1112 		/* always receive -E2BIG or true error if n > rest */
1113 	}
1114 	return err;
1115 }
1116 
1117 static int nilfs_segctor_collect_blocks(struct nilfs_sc_info *sci, int mode)
1118 {
1119 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
1120 	struct list_head *head;
1121 	struct nilfs_inode_info *ii;
1122 	size_t ndone;
1123 	int err = 0;
1124 
1125 	switch (nilfs_sc_cstage_get(sci)) {
1126 	case NILFS_ST_INIT:
1127 		/* Pre-processes */
1128 		sci->sc_stage.flags = 0;
1129 
1130 		if (!test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags)) {
1131 			sci->sc_nblk_inc = 0;
1132 			sci->sc_curseg->sb_sum.flags = NILFS_SS_LOGBGN;
1133 			if (mode == SC_LSEG_DSYNC) {
1134 				nilfs_sc_cstage_set(sci, NILFS_ST_DSYNC);
1135 				goto dsync_mode;
1136 			}
1137 		}
1138 
1139 		sci->sc_stage.dirty_file_ptr = NULL;
1140 		sci->sc_stage.gc_inode_ptr = NULL;
1141 		if (mode == SC_FLUSH_DAT) {
1142 			nilfs_sc_cstage_set(sci, NILFS_ST_DAT);
1143 			goto dat_stage;
1144 		}
1145 		nilfs_sc_cstage_inc(sci);
1146 		fallthrough;
1147 	case NILFS_ST_GC:
1148 		if (nilfs_doing_gc()) {
1149 			head = &sci->sc_gc_inodes;
1150 			ii = list_prepare_entry(sci->sc_stage.gc_inode_ptr,
1151 						head, i_dirty);
1152 			list_for_each_entry_continue(ii, head, i_dirty) {
1153 				err = nilfs_segctor_scan_file(
1154 					sci, &ii->vfs_inode,
1155 					&nilfs_sc_file_ops);
1156 				if (unlikely(err)) {
1157 					sci->sc_stage.gc_inode_ptr = list_entry(
1158 						ii->i_dirty.prev,
1159 						struct nilfs_inode_info,
1160 						i_dirty);
1161 					goto break_or_fail;
1162 				}
1163 				set_bit(NILFS_I_COLLECTED, &ii->i_state);
1164 			}
1165 			sci->sc_stage.gc_inode_ptr = NULL;
1166 		}
1167 		nilfs_sc_cstage_inc(sci);
1168 		fallthrough;
1169 	case NILFS_ST_FILE:
1170 		head = &sci->sc_dirty_files;
1171 		ii = list_prepare_entry(sci->sc_stage.dirty_file_ptr, head,
1172 					i_dirty);
1173 		list_for_each_entry_continue(ii, head, i_dirty) {
1174 			clear_bit(NILFS_I_DIRTY, &ii->i_state);
1175 
1176 			err = nilfs_segctor_scan_file(sci, &ii->vfs_inode,
1177 						      &nilfs_sc_file_ops);
1178 			if (unlikely(err)) {
1179 				sci->sc_stage.dirty_file_ptr =
1180 					list_entry(ii->i_dirty.prev,
1181 						   struct nilfs_inode_info,
1182 						   i_dirty);
1183 				goto break_or_fail;
1184 			}
1185 			/* sci->sc_stage.dirty_file_ptr = NILFS_I(inode); */
1186 			/* XXX: required ? */
1187 		}
1188 		sci->sc_stage.dirty_file_ptr = NULL;
1189 		if (mode == SC_FLUSH_FILE) {
1190 			nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1191 			return 0;
1192 		}
1193 		nilfs_sc_cstage_inc(sci);
1194 		sci->sc_stage.flags |= NILFS_CF_IFILE_STARTED;
1195 		fallthrough;
1196 	case NILFS_ST_IFILE:
1197 		err = nilfs_segctor_scan_file(sci, sci->sc_root->ifile,
1198 					      &nilfs_sc_file_ops);
1199 		if (unlikely(err))
1200 			break;
1201 		nilfs_sc_cstage_inc(sci);
1202 		/* Creating a checkpoint */
1203 		err = nilfs_segctor_create_checkpoint(sci);
1204 		if (unlikely(err))
1205 			break;
1206 		fallthrough;
1207 	case NILFS_ST_CPFILE:
1208 		err = nilfs_segctor_scan_file(sci, nilfs->ns_cpfile,
1209 					      &nilfs_sc_file_ops);
1210 		if (unlikely(err))
1211 			break;
1212 		nilfs_sc_cstage_inc(sci);
1213 		fallthrough;
1214 	case NILFS_ST_SUFILE:
1215 		err = nilfs_sufile_freev(nilfs->ns_sufile, sci->sc_freesegs,
1216 					 sci->sc_nfreesegs, &ndone);
1217 		if (unlikely(err)) {
1218 			nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1219 						  sci->sc_freesegs, ndone,
1220 						  NULL);
1221 			break;
1222 		}
1223 		sci->sc_stage.flags |= NILFS_CF_SUFREED;
1224 
1225 		err = nilfs_segctor_scan_file(sci, nilfs->ns_sufile,
1226 					      &nilfs_sc_file_ops);
1227 		if (unlikely(err))
1228 			break;
1229 		nilfs_sc_cstage_inc(sci);
1230 		fallthrough;
1231 	case NILFS_ST_DAT:
1232  dat_stage:
1233 		err = nilfs_segctor_scan_file(sci, nilfs->ns_dat,
1234 					      &nilfs_sc_dat_ops);
1235 		if (unlikely(err))
1236 			break;
1237 		if (mode == SC_FLUSH_DAT) {
1238 			nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1239 			return 0;
1240 		}
1241 		nilfs_sc_cstage_inc(sci);
1242 		fallthrough;
1243 	case NILFS_ST_SR:
1244 		if (mode == SC_LSEG_SR) {
1245 			/* Appending a super root */
1246 			err = nilfs_segctor_add_super_root(sci);
1247 			if (unlikely(err))
1248 				break;
1249 		}
1250 		/* End of a logical segment */
1251 		sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
1252 		nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1253 		return 0;
1254 	case NILFS_ST_DSYNC:
1255  dsync_mode:
1256 		sci->sc_curseg->sb_sum.flags |= NILFS_SS_SYNDT;
1257 		ii = sci->sc_dsync_inode;
1258 		if (!test_bit(NILFS_I_BUSY, &ii->i_state))
1259 			break;
1260 
1261 		err = nilfs_segctor_scan_file_dsync(sci, &ii->vfs_inode);
1262 		if (unlikely(err))
1263 			break;
1264 		sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
1265 		nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1266 		return 0;
1267 	case NILFS_ST_DONE:
1268 		return 0;
1269 	default:
1270 		BUG();
1271 	}
1272 
1273  break_or_fail:
1274 	return err;
1275 }
1276 
1277 /**
1278  * nilfs_segctor_begin_construction - setup segment buffer to make a new log
1279  * @sci: nilfs_sc_info
1280  * @nilfs: nilfs object
1281  */
1282 static int nilfs_segctor_begin_construction(struct nilfs_sc_info *sci,
1283 					    struct the_nilfs *nilfs)
1284 {
1285 	struct nilfs_segment_buffer *segbuf, *prev;
1286 	__u64 nextnum;
1287 	int err, alloc = 0;
1288 
1289 	segbuf = nilfs_segbuf_new(sci->sc_super);
1290 	if (unlikely(!segbuf))
1291 		return -ENOMEM;
1292 
1293 	if (list_empty(&sci->sc_write_logs)) {
1294 		nilfs_segbuf_map(segbuf, nilfs->ns_segnum,
1295 				 nilfs->ns_pseg_offset, nilfs);
1296 		if (segbuf->sb_rest_blocks < NILFS_PSEG_MIN_BLOCKS) {
1297 			nilfs_shift_to_next_segment(nilfs);
1298 			nilfs_segbuf_map(segbuf, nilfs->ns_segnum, 0, nilfs);
1299 		}
1300 
1301 		segbuf->sb_sum.seg_seq = nilfs->ns_seg_seq;
1302 		nextnum = nilfs->ns_nextnum;
1303 
1304 		if (nilfs->ns_segnum == nilfs->ns_nextnum)
1305 			/* Start from the head of a new full segment */
1306 			alloc++;
1307 	} else {
1308 		/* Continue logs */
1309 		prev = NILFS_LAST_SEGBUF(&sci->sc_write_logs);
1310 		nilfs_segbuf_map_cont(segbuf, prev);
1311 		segbuf->sb_sum.seg_seq = prev->sb_sum.seg_seq;
1312 		nextnum = prev->sb_nextnum;
1313 
1314 		if (segbuf->sb_rest_blocks < NILFS_PSEG_MIN_BLOCKS) {
1315 			nilfs_segbuf_map(segbuf, prev->sb_nextnum, 0, nilfs);
1316 			segbuf->sb_sum.seg_seq++;
1317 			alloc++;
1318 		}
1319 	}
1320 
1321 	err = nilfs_sufile_mark_dirty(nilfs->ns_sufile, segbuf->sb_segnum);
1322 	if (err)
1323 		goto failed;
1324 
1325 	if (alloc) {
1326 		err = nilfs_sufile_alloc(nilfs->ns_sufile, &nextnum);
1327 		if (err)
1328 			goto failed;
1329 	}
1330 	nilfs_segbuf_set_next_segnum(segbuf, nextnum, nilfs);
1331 
1332 	BUG_ON(!list_empty(&sci->sc_segbufs));
1333 	list_add_tail(&segbuf->sb_list, &sci->sc_segbufs);
1334 	sci->sc_segbuf_nblocks = segbuf->sb_rest_blocks;
1335 	return 0;
1336 
1337  failed:
1338 	nilfs_segbuf_free(segbuf);
1339 	return err;
1340 }
1341 
1342 static int nilfs_segctor_extend_segments(struct nilfs_sc_info *sci,
1343 					 struct the_nilfs *nilfs, int nadd)
1344 {
1345 	struct nilfs_segment_buffer *segbuf, *prev;
1346 	struct inode *sufile = nilfs->ns_sufile;
1347 	__u64 nextnextnum;
1348 	LIST_HEAD(list);
1349 	int err, ret, i;
1350 
1351 	prev = NILFS_LAST_SEGBUF(&sci->sc_segbufs);
1352 	/*
1353 	 * Since the segment specified with nextnum might be allocated during
1354 	 * the previous construction, the buffer including its segusage may
1355 	 * not be dirty.  The following call ensures that the buffer is dirty
1356 	 * and will pin the buffer on memory until the sufile is written.
1357 	 */
1358 	err = nilfs_sufile_mark_dirty(sufile, prev->sb_nextnum);
1359 	if (unlikely(err))
1360 		return err;
1361 
1362 	for (i = 0; i < nadd; i++) {
1363 		/* extend segment info */
1364 		err = -ENOMEM;
1365 		segbuf = nilfs_segbuf_new(sci->sc_super);
1366 		if (unlikely(!segbuf))
1367 			goto failed;
1368 
1369 		/* map this buffer to region of segment on-disk */
1370 		nilfs_segbuf_map(segbuf, prev->sb_nextnum, 0, nilfs);
1371 		sci->sc_segbuf_nblocks += segbuf->sb_rest_blocks;
1372 
1373 		/* allocate the next next full segment */
1374 		err = nilfs_sufile_alloc(sufile, &nextnextnum);
1375 		if (unlikely(err))
1376 			goto failed_segbuf;
1377 
1378 		segbuf->sb_sum.seg_seq = prev->sb_sum.seg_seq + 1;
1379 		nilfs_segbuf_set_next_segnum(segbuf, nextnextnum, nilfs);
1380 
1381 		list_add_tail(&segbuf->sb_list, &list);
1382 		prev = segbuf;
1383 	}
1384 	list_splice_tail(&list, &sci->sc_segbufs);
1385 	return 0;
1386 
1387  failed_segbuf:
1388 	nilfs_segbuf_free(segbuf);
1389  failed:
1390 	list_for_each_entry(segbuf, &list, sb_list) {
1391 		ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1392 		WARN_ON(ret); /* never fails */
1393 	}
1394 	nilfs_destroy_logs(&list);
1395 	return err;
1396 }
1397 
1398 static void nilfs_free_incomplete_logs(struct list_head *logs,
1399 				       struct the_nilfs *nilfs)
1400 {
1401 	struct nilfs_segment_buffer *segbuf, *prev;
1402 	struct inode *sufile = nilfs->ns_sufile;
1403 	int ret;
1404 
1405 	segbuf = NILFS_FIRST_SEGBUF(logs);
1406 	if (nilfs->ns_nextnum != segbuf->sb_nextnum) {
1407 		ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1408 		WARN_ON(ret); /* never fails */
1409 	}
1410 	if (atomic_read(&segbuf->sb_err)) {
1411 		/* Case 1: The first segment failed */
1412 		if (segbuf->sb_pseg_start != segbuf->sb_fseg_start)
1413 			/*
1414 			 * Case 1a:  Partial segment appended into an existing
1415 			 * segment
1416 			 */
1417 			nilfs_terminate_segment(nilfs, segbuf->sb_fseg_start,
1418 						segbuf->sb_fseg_end);
1419 		else /* Case 1b:  New full segment */
1420 			set_nilfs_discontinued(nilfs);
1421 	}
1422 
1423 	prev = segbuf;
1424 	list_for_each_entry_continue(segbuf, logs, sb_list) {
1425 		if (prev->sb_nextnum != segbuf->sb_nextnum) {
1426 			ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1427 			WARN_ON(ret); /* never fails */
1428 		}
1429 		if (atomic_read(&segbuf->sb_err) &&
1430 		    segbuf->sb_segnum != nilfs->ns_nextnum)
1431 			/* Case 2: extended segment (!= next) failed */
1432 			nilfs_sufile_set_error(sufile, segbuf->sb_segnum);
1433 		prev = segbuf;
1434 	}
1435 }
1436 
1437 static void nilfs_segctor_update_segusage(struct nilfs_sc_info *sci,
1438 					  struct inode *sufile)
1439 {
1440 	struct nilfs_segment_buffer *segbuf;
1441 	unsigned long live_blocks;
1442 	int ret;
1443 
1444 	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1445 		live_blocks = segbuf->sb_sum.nblocks +
1446 			(segbuf->sb_pseg_start - segbuf->sb_fseg_start);
1447 		ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1448 						     live_blocks,
1449 						     sci->sc_seg_ctime);
1450 		WARN_ON(ret); /* always succeed because the segusage is dirty */
1451 	}
1452 }
1453 
1454 static void nilfs_cancel_segusage(struct list_head *logs, struct inode *sufile)
1455 {
1456 	struct nilfs_segment_buffer *segbuf;
1457 	int ret;
1458 
1459 	segbuf = NILFS_FIRST_SEGBUF(logs);
1460 	ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1461 					     segbuf->sb_pseg_start -
1462 					     segbuf->sb_fseg_start, 0);
1463 	WARN_ON(ret); /* always succeed because the segusage is dirty */
1464 
1465 	list_for_each_entry_continue(segbuf, logs, sb_list) {
1466 		ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1467 						     0, 0);
1468 		WARN_ON(ret); /* always succeed */
1469 	}
1470 }
1471 
1472 static void nilfs_segctor_truncate_segments(struct nilfs_sc_info *sci,
1473 					    struct nilfs_segment_buffer *last,
1474 					    struct inode *sufile)
1475 {
1476 	struct nilfs_segment_buffer *segbuf = last;
1477 	int ret;
1478 
1479 	list_for_each_entry_continue(segbuf, &sci->sc_segbufs, sb_list) {
1480 		sci->sc_segbuf_nblocks -= segbuf->sb_rest_blocks;
1481 		ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1482 		WARN_ON(ret);
1483 	}
1484 	nilfs_truncate_logs(&sci->sc_segbufs, last);
1485 }
1486 
1487 
1488 static int nilfs_segctor_collect(struct nilfs_sc_info *sci,
1489 				 struct the_nilfs *nilfs, int mode)
1490 {
1491 	struct nilfs_cstage prev_stage = sci->sc_stage;
1492 	int err, nadd = 1;
1493 
1494 	/* Collection retry loop */
1495 	for (;;) {
1496 		sci->sc_nblk_this_inc = 0;
1497 		sci->sc_curseg = NILFS_FIRST_SEGBUF(&sci->sc_segbufs);
1498 
1499 		err = nilfs_segctor_reset_segment_buffer(sci);
1500 		if (unlikely(err))
1501 			goto failed;
1502 
1503 		err = nilfs_segctor_collect_blocks(sci, mode);
1504 		sci->sc_nblk_this_inc += sci->sc_curseg->sb_sum.nblocks;
1505 		if (!err)
1506 			break;
1507 
1508 		if (unlikely(err != -E2BIG))
1509 			goto failed;
1510 
1511 		/* The current segment is filled up */
1512 		if (mode != SC_LSEG_SR ||
1513 		    nilfs_sc_cstage_get(sci) < NILFS_ST_CPFILE)
1514 			break;
1515 
1516 		nilfs_clear_logs(&sci->sc_segbufs);
1517 
1518 		if (sci->sc_stage.flags & NILFS_CF_SUFREED) {
1519 			err = nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1520 							sci->sc_freesegs,
1521 							sci->sc_nfreesegs,
1522 							NULL);
1523 			WARN_ON(err); /* do not happen */
1524 			sci->sc_stage.flags &= ~NILFS_CF_SUFREED;
1525 		}
1526 
1527 		err = nilfs_segctor_extend_segments(sci, nilfs, nadd);
1528 		if (unlikely(err))
1529 			return err;
1530 
1531 		nadd = min_t(int, nadd << 1, SC_MAX_SEGDELTA);
1532 		sci->sc_stage = prev_stage;
1533 	}
1534 	nilfs_segctor_truncate_segments(sci, sci->sc_curseg, nilfs->ns_sufile);
1535 	return 0;
1536 
1537  failed:
1538 	return err;
1539 }
1540 
1541 static void nilfs_list_replace_buffer(struct buffer_head *old_bh,
1542 				      struct buffer_head *new_bh)
1543 {
1544 	BUG_ON(!list_empty(&new_bh->b_assoc_buffers));
1545 
1546 	list_replace_init(&old_bh->b_assoc_buffers, &new_bh->b_assoc_buffers);
1547 	/* The caller must release old_bh */
1548 }
1549 
1550 static int
1551 nilfs_segctor_update_payload_blocknr(struct nilfs_sc_info *sci,
1552 				     struct nilfs_segment_buffer *segbuf,
1553 				     int mode)
1554 {
1555 	struct inode *inode = NULL;
1556 	sector_t blocknr;
1557 	unsigned long nfinfo = segbuf->sb_sum.nfinfo;
1558 	unsigned long nblocks = 0, ndatablk = 0;
1559 	const struct nilfs_sc_operations *sc_op = NULL;
1560 	struct nilfs_segsum_pointer ssp;
1561 	struct nilfs_finfo *finfo = NULL;
1562 	union nilfs_binfo binfo;
1563 	struct buffer_head *bh, *bh_org;
1564 	ino_t ino = 0;
1565 	int err = 0;
1566 
1567 	if (!nfinfo)
1568 		goto out;
1569 
1570 	blocknr = segbuf->sb_pseg_start + segbuf->sb_sum.nsumblk;
1571 	ssp.bh = NILFS_SEGBUF_FIRST_BH(&segbuf->sb_segsum_buffers);
1572 	ssp.offset = sizeof(struct nilfs_segment_summary);
1573 
1574 	list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
1575 		if (bh == segbuf->sb_super_root)
1576 			break;
1577 		if (!finfo) {
1578 			finfo =	nilfs_segctor_map_segsum_entry(
1579 				sci, &ssp, sizeof(*finfo));
1580 			ino = le64_to_cpu(finfo->fi_ino);
1581 			nblocks = le32_to_cpu(finfo->fi_nblocks);
1582 			ndatablk = le32_to_cpu(finfo->fi_ndatablk);
1583 
1584 			inode = bh->b_page->mapping->host;
1585 
1586 			if (mode == SC_LSEG_DSYNC)
1587 				sc_op = &nilfs_sc_dsync_ops;
1588 			else if (ino == NILFS_DAT_INO)
1589 				sc_op = &nilfs_sc_dat_ops;
1590 			else /* file blocks */
1591 				sc_op = &nilfs_sc_file_ops;
1592 		}
1593 		bh_org = bh;
1594 		get_bh(bh_org);
1595 		err = nilfs_bmap_assign(NILFS_I(inode)->i_bmap, &bh, blocknr,
1596 					&binfo);
1597 		if (bh != bh_org)
1598 			nilfs_list_replace_buffer(bh_org, bh);
1599 		brelse(bh_org);
1600 		if (unlikely(err))
1601 			goto failed_bmap;
1602 
1603 		if (ndatablk > 0)
1604 			sc_op->write_data_binfo(sci, &ssp, &binfo);
1605 		else
1606 			sc_op->write_node_binfo(sci, &ssp, &binfo);
1607 
1608 		blocknr++;
1609 		if (--nblocks == 0) {
1610 			finfo = NULL;
1611 			if (--nfinfo == 0)
1612 				break;
1613 		} else if (ndatablk > 0)
1614 			ndatablk--;
1615 	}
1616  out:
1617 	return 0;
1618 
1619  failed_bmap:
1620 	return err;
1621 }
1622 
1623 static int nilfs_segctor_assign(struct nilfs_sc_info *sci, int mode)
1624 {
1625 	struct nilfs_segment_buffer *segbuf;
1626 	int err;
1627 
1628 	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1629 		err = nilfs_segctor_update_payload_blocknr(sci, segbuf, mode);
1630 		if (unlikely(err))
1631 			return err;
1632 		nilfs_segbuf_fill_in_segsum(segbuf);
1633 	}
1634 	return 0;
1635 }
1636 
1637 static void nilfs_begin_page_io(struct page *page)
1638 {
1639 	if (!page || PageWriteback(page))
1640 		/*
1641 		 * For split b-tree node pages, this function may be called
1642 		 * twice.  We ignore the 2nd or later calls by this check.
1643 		 */
1644 		return;
1645 
1646 	lock_page(page);
1647 	clear_page_dirty_for_io(page);
1648 	set_page_writeback(page);
1649 	unlock_page(page);
1650 }
1651 
1652 static void nilfs_segctor_prepare_write(struct nilfs_sc_info *sci)
1653 {
1654 	struct nilfs_segment_buffer *segbuf;
1655 	struct page *bd_page = NULL, *fs_page = NULL;
1656 
1657 	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1658 		struct buffer_head *bh;
1659 
1660 		list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1661 				    b_assoc_buffers) {
1662 			if (bh->b_page != bd_page) {
1663 				if (bd_page) {
1664 					lock_page(bd_page);
1665 					clear_page_dirty_for_io(bd_page);
1666 					set_page_writeback(bd_page);
1667 					unlock_page(bd_page);
1668 				}
1669 				bd_page = bh->b_page;
1670 			}
1671 		}
1672 
1673 		list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1674 				    b_assoc_buffers) {
1675 			set_buffer_async_write(bh);
1676 			if (bh == segbuf->sb_super_root) {
1677 				if (bh->b_page != bd_page) {
1678 					lock_page(bd_page);
1679 					clear_page_dirty_for_io(bd_page);
1680 					set_page_writeback(bd_page);
1681 					unlock_page(bd_page);
1682 					bd_page = bh->b_page;
1683 				}
1684 				break;
1685 			}
1686 			if (bh->b_page != fs_page) {
1687 				nilfs_begin_page_io(fs_page);
1688 				fs_page = bh->b_page;
1689 			}
1690 		}
1691 	}
1692 	if (bd_page) {
1693 		lock_page(bd_page);
1694 		clear_page_dirty_for_io(bd_page);
1695 		set_page_writeback(bd_page);
1696 		unlock_page(bd_page);
1697 	}
1698 	nilfs_begin_page_io(fs_page);
1699 }
1700 
1701 static int nilfs_segctor_write(struct nilfs_sc_info *sci,
1702 			       struct the_nilfs *nilfs)
1703 {
1704 	int ret;
1705 
1706 	ret = nilfs_write_logs(&sci->sc_segbufs, nilfs);
1707 	list_splice_tail_init(&sci->sc_segbufs, &sci->sc_write_logs);
1708 	return ret;
1709 }
1710 
1711 static void nilfs_end_page_io(struct page *page, int err)
1712 {
1713 	if (!page)
1714 		return;
1715 
1716 	if (buffer_nilfs_node(page_buffers(page)) && !PageWriteback(page)) {
1717 		/*
1718 		 * For b-tree node pages, this function may be called twice
1719 		 * or more because they might be split in a segment.
1720 		 */
1721 		if (PageDirty(page)) {
1722 			/*
1723 			 * For pages holding split b-tree node buffers, dirty
1724 			 * flag on the buffers may be cleared discretely.
1725 			 * In that case, the page is once redirtied for
1726 			 * remaining buffers, and it must be cancelled if
1727 			 * all the buffers get cleaned later.
1728 			 */
1729 			lock_page(page);
1730 			if (nilfs_page_buffers_clean(page))
1731 				__nilfs_clear_page_dirty(page);
1732 			unlock_page(page);
1733 		}
1734 		return;
1735 	}
1736 
1737 	if (!err) {
1738 		if (!nilfs_page_buffers_clean(page))
1739 			__set_page_dirty_nobuffers(page);
1740 		ClearPageError(page);
1741 	} else {
1742 		__set_page_dirty_nobuffers(page);
1743 		SetPageError(page);
1744 	}
1745 
1746 	end_page_writeback(page);
1747 }
1748 
1749 static void nilfs_abort_logs(struct list_head *logs, int err)
1750 {
1751 	struct nilfs_segment_buffer *segbuf;
1752 	struct page *bd_page = NULL, *fs_page = NULL;
1753 	struct buffer_head *bh;
1754 
1755 	if (list_empty(logs))
1756 		return;
1757 
1758 	list_for_each_entry(segbuf, logs, sb_list) {
1759 		list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1760 				    b_assoc_buffers) {
1761 			if (bh->b_page != bd_page) {
1762 				if (bd_page)
1763 					end_page_writeback(bd_page);
1764 				bd_page = bh->b_page;
1765 			}
1766 		}
1767 
1768 		list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1769 				    b_assoc_buffers) {
1770 			clear_buffer_async_write(bh);
1771 			if (bh == segbuf->sb_super_root) {
1772 				if (bh->b_page != bd_page) {
1773 					end_page_writeback(bd_page);
1774 					bd_page = bh->b_page;
1775 				}
1776 				break;
1777 			}
1778 			if (bh->b_page != fs_page) {
1779 				nilfs_end_page_io(fs_page, err);
1780 				fs_page = bh->b_page;
1781 			}
1782 		}
1783 	}
1784 	if (bd_page)
1785 		end_page_writeback(bd_page);
1786 
1787 	nilfs_end_page_io(fs_page, err);
1788 }
1789 
1790 static void nilfs_segctor_abort_construction(struct nilfs_sc_info *sci,
1791 					     struct the_nilfs *nilfs, int err)
1792 {
1793 	LIST_HEAD(logs);
1794 	int ret;
1795 
1796 	list_splice_tail_init(&sci->sc_write_logs, &logs);
1797 	ret = nilfs_wait_on_logs(&logs);
1798 	nilfs_abort_logs(&logs, ret ? : err);
1799 
1800 	list_splice_tail_init(&sci->sc_segbufs, &logs);
1801 	nilfs_cancel_segusage(&logs, nilfs->ns_sufile);
1802 	nilfs_free_incomplete_logs(&logs, nilfs);
1803 
1804 	if (sci->sc_stage.flags & NILFS_CF_SUFREED) {
1805 		ret = nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1806 						sci->sc_freesegs,
1807 						sci->sc_nfreesegs,
1808 						NULL);
1809 		WARN_ON(ret); /* do not happen */
1810 	}
1811 
1812 	nilfs_destroy_logs(&logs);
1813 }
1814 
1815 static void nilfs_set_next_segment(struct the_nilfs *nilfs,
1816 				   struct nilfs_segment_buffer *segbuf)
1817 {
1818 	nilfs->ns_segnum = segbuf->sb_segnum;
1819 	nilfs->ns_nextnum = segbuf->sb_nextnum;
1820 	nilfs->ns_pseg_offset = segbuf->sb_pseg_start - segbuf->sb_fseg_start
1821 		+ segbuf->sb_sum.nblocks;
1822 	nilfs->ns_seg_seq = segbuf->sb_sum.seg_seq;
1823 	nilfs->ns_ctime = segbuf->sb_sum.ctime;
1824 }
1825 
1826 static void nilfs_segctor_complete_write(struct nilfs_sc_info *sci)
1827 {
1828 	struct nilfs_segment_buffer *segbuf;
1829 	struct page *bd_page = NULL, *fs_page = NULL;
1830 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
1831 	int update_sr = false;
1832 
1833 	list_for_each_entry(segbuf, &sci->sc_write_logs, sb_list) {
1834 		struct buffer_head *bh;
1835 
1836 		list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1837 				    b_assoc_buffers) {
1838 			set_buffer_uptodate(bh);
1839 			clear_buffer_dirty(bh);
1840 			if (bh->b_page != bd_page) {
1841 				if (bd_page)
1842 					end_page_writeback(bd_page);
1843 				bd_page = bh->b_page;
1844 			}
1845 		}
1846 		/*
1847 		 * We assume that the buffers which belong to the same page
1848 		 * continue over the buffer list.
1849 		 * Under this assumption, the last BHs of pages is
1850 		 * identifiable by the discontinuity of bh->b_page
1851 		 * (page != fs_page).
1852 		 *
1853 		 * For B-tree node blocks, however, this assumption is not
1854 		 * guaranteed.  The cleanup code of B-tree node pages needs
1855 		 * special care.
1856 		 */
1857 		list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1858 				    b_assoc_buffers) {
1859 			const unsigned long set_bits = BIT(BH_Uptodate);
1860 			const unsigned long clear_bits =
1861 				(BIT(BH_Dirty) | BIT(BH_Async_Write) |
1862 				 BIT(BH_Delay) | BIT(BH_NILFS_Volatile) |
1863 				 BIT(BH_NILFS_Redirected));
1864 
1865 			set_mask_bits(&bh->b_state, clear_bits, set_bits);
1866 			if (bh == segbuf->sb_super_root) {
1867 				if (bh->b_page != bd_page) {
1868 					end_page_writeback(bd_page);
1869 					bd_page = bh->b_page;
1870 				}
1871 				update_sr = true;
1872 				break;
1873 			}
1874 			if (bh->b_page != fs_page) {
1875 				nilfs_end_page_io(fs_page, 0);
1876 				fs_page = bh->b_page;
1877 			}
1878 		}
1879 
1880 		if (!nilfs_segbuf_simplex(segbuf)) {
1881 			if (segbuf->sb_sum.flags & NILFS_SS_LOGBGN) {
1882 				set_bit(NILFS_SC_UNCLOSED, &sci->sc_flags);
1883 				sci->sc_lseg_stime = jiffies;
1884 			}
1885 			if (segbuf->sb_sum.flags & NILFS_SS_LOGEND)
1886 				clear_bit(NILFS_SC_UNCLOSED, &sci->sc_flags);
1887 		}
1888 	}
1889 	/*
1890 	 * Since pages may continue over multiple segment buffers,
1891 	 * end of the last page must be checked outside of the loop.
1892 	 */
1893 	if (bd_page)
1894 		end_page_writeback(bd_page);
1895 
1896 	nilfs_end_page_io(fs_page, 0);
1897 
1898 	nilfs_drop_collected_inodes(&sci->sc_dirty_files);
1899 
1900 	if (nilfs_doing_gc())
1901 		nilfs_drop_collected_inodes(&sci->sc_gc_inodes);
1902 	else
1903 		nilfs->ns_nongc_ctime = sci->sc_seg_ctime;
1904 
1905 	sci->sc_nblk_inc += sci->sc_nblk_this_inc;
1906 
1907 	segbuf = NILFS_LAST_SEGBUF(&sci->sc_write_logs);
1908 	nilfs_set_next_segment(nilfs, segbuf);
1909 
1910 	if (update_sr) {
1911 		nilfs->ns_flushed_device = 0;
1912 		nilfs_set_last_segment(nilfs, segbuf->sb_pseg_start,
1913 				       segbuf->sb_sum.seg_seq, nilfs->ns_cno++);
1914 
1915 		clear_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
1916 		clear_bit(NILFS_SC_DIRTY, &sci->sc_flags);
1917 		set_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags);
1918 		nilfs_segctor_clear_metadata_dirty(sci);
1919 	} else
1920 		clear_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags);
1921 }
1922 
1923 static int nilfs_segctor_wait(struct nilfs_sc_info *sci)
1924 {
1925 	int ret;
1926 
1927 	ret = nilfs_wait_on_logs(&sci->sc_write_logs);
1928 	if (!ret) {
1929 		nilfs_segctor_complete_write(sci);
1930 		nilfs_destroy_logs(&sci->sc_write_logs);
1931 	}
1932 	return ret;
1933 }
1934 
1935 static int nilfs_segctor_collect_dirty_files(struct nilfs_sc_info *sci,
1936 					     struct the_nilfs *nilfs)
1937 {
1938 	struct nilfs_inode_info *ii, *n;
1939 	struct inode *ifile = sci->sc_root->ifile;
1940 
1941 	spin_lock(&nilfs->ns_inode_lock);
1942  retry:
1943 	list_for_each_entry_safe(ii, n, &nilfs->ns_dirty_files, i_dirty) {
1944 		if (!ii->i_bh) {
1945 			struct buffer_head *ibh;
1946 			int err;
1947 
1948 			spin_unlock(&nilfs->ns_inode_lock);
1949 			err = nilfs_ifile_get_inode_block(
1950 				ifile, ii->vfs_inode.i_ino, &ibh);
1951 			if (unlikely(err)) {
1952 				nilfs_warn(sci->sc_super,
1953 					   "log writer: error %d getting inode block (ino=%lu)",
1954 					   err, ii->vfs_inode.i_ino);
1955 				return err;
1956 			}
1957 			spin_lock(&nilfs->ns_inode_lock);
1958 			if (likely(!ii->i_bh))
1959 				ii->i_bh = ibh;
1960 			else
1961 				brelse(ibh);
1962 			goto retry;
1963 		}
1964 
1965 		// Always redirty the buffer to avoid race condition
1966 		mark_buffer_dirty(ii->i_bh);
1967 		nilfs_mdt_mark_dirty(ifile);
1968 
1969 		clear_bit(NILFS_I_QUEUED, &ii->i_state);
1970 		set_bit(NILFS_I_BUSY, &ii->i_state);
1971 		list_move_tail(&ii->i_dirty, &sci->sc_dirty_files);
1972 	}
1973 	spin_unlock(&nilfs->ns_inode_lock);
1974 
1975 	return 0;
1976 }
1977 
1978 static void nilfs_segctor_drop_written_files(struct nilfs_sc_info *sci,
1979 					     struct the_nilfs *nilfs)
1980 {
1981 	struct nilfs_inode_info *ii, *n;
1982 	int during_mount = !(sci->sc_super->s_flags & SB_ACTIVE);
1983 	int defer_iput = false;
1984 
1985 	spin_lock(&nilfs->ns_inode_lock);
1986 	list_for_each_entry_safe(ii, n, &sci->sc_dirty_files, i_dirty) {
1987 		if (!test_and_clear_bit(NILFS_I_UPDATED, &ii->i_state) ||
1988 		    test_bit(NILFS_I_DIRTY, &ii->i_state))
1989 			continue;
1990 
1991 		clear_bit(NILFS_I_BUSY, &ii->i_state);
1992 		brelse(ii->i_bh);
1993 		ii->i_bh = NULL;
1994 		list_del_init(&ii->i_dirty);
1995 		if (!ii->vfs_inode.i_nlink || during_mount) {
1996 			/*
1997 			 * Defer calling iput() to avoid deadlocks if
1998 			 * i_nlink == 0 or mount is not yet finished.
1999 			 */
2000 			list_add_tail(&ii->i_dirty, &sci->sc_iput_queue);
2001 			defer_iput = true;
2002 		} else {
2003 			spin_unlock(&nilfs->ns_inode_lock);
2004 			iput(&ii->vfs_inode);
2005 			spin_lock(&nilfs->ns_inode_lock);
2006 		}
2007 	}
2008 	spin_unlock(&nilfs->ns_inode_lock);
2009 
2010 	if (defer_iput)
2011 		schedule_work(&sci->sc_iput_work);
2012 }
2013 
2014 /*
2015  * Main procedure of segment constructor
2016  */
2017 static int nilfs_segctor_do_construct(struct nilfs_sc_info *sci, int mode)
2018 {
2019 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2020 	int err;
2021 
2022 	nilfs_sc_cstage_set(sci, NILFS_ST_INIT);
2023 	sci->sc_cno = nilfs->ns_cno;
2024 
2025 	err = nilfs_segctor_collect_dirty_files(sci, nilfs);
2026 	if (unlikely(err))
2027 		goto out;
2028 
2029 	if (nilfs_test_metadata_dirty(nilfs, sci->sc_root))
2030 		set_bit(NILFS_SC_DIRTY, &sci->sc_flags);
2031 
2032 	if (nilfs_segctor_clean(sci))
2033 		goto out;
2034 
2035 	do {
2036 		sci->sc_stage.flags &= ~NILFS_CF_HISTORY_MASK;
2037 
2038 		err = nilfs_segctor_begin_construction(sci, nilfs);
2039 		if (unlikely(err))
2040 			goto out;
2041 
2042 		/* Update time stamp */
2043 		sci->sc_seg_ctime = ktime_get_real_seconds();
2044 
2045 		err = nilfs_segctor_collect(sci, nilfs, mode);
2046 		if (unlikely(err))
2047 			goto failed;
2048 
2049 		/* Avoid empty segment */
2050 		if (nilfs_sc_cstage_get(sci) == NILFS_ST_DONE &&
2051 		    nilfs_segbuf_empty(sci->sc_curseg)) {
2052 			nilfs_segctor_abort_construction(sci, nilfs, 1);
2053 			goto out;
2054 		}
2055 
2056 		err = nilfs_segctor_assign(sci, mode);
2057 		if (unlikely(err))
2058 			goto failed;
2059 
2060 		if (sci->sc_stage.flags & NILFS_CF_IFILE_STARTED)
2061 			nilfs_segctor_fill_in_file_bmap(sci);
2062 
2063 		if (mode == SC_LSEG_SR &&
2064 		    nilfs_sc_cstage_get(sci) >= NILFS_ST_CPFILE) {
2065 			err = nilfs_segctor_fill_in_checkpoint(sci);
2066 			if (unlikely(err))
2067 				goto failed_to_write;
2068 
2069 			nilfs_segctor_fill_in_super_root(sci, nilfs);
2070 		}
2071 		nilfs_segctor_update_segusage(sci, nilfs->ns_sufile);
2072 
2073 		/* Write partial segments */
2074 		nilfs_segctor_prepare_write(sci);
2075 
2076 		nilfs_add_checksums_on_logs(&sci->sc_segbufs,
2077 					    nilfs->ns_crc_seed);
2078 
2079 		err = nilfs_segctor_write(sci, nilfs);
2080 		if (unlikely(err))
2081 			goto failed_to_write;
2082 
2083 		if (nilfs_sc_cstage_get(sci) == NILFS_ST_DONE ||
2084 		    nilfs->ns_blocksize_bits != PAGE_SHIFT) {
2085 			/*
2086 			 * At this point, we avoid double buffering
2087 			 * for blocksize < pagesize because page dirty
2088 			 * flag is turned off during write and dirty
2089 			 * buffers are not properly collected for
2090 			 * pages crossing over segments.
2091 			 */
2092 			err = nilfs_segctor_wait(sci);
2093 			if (err)
2094 				goto failed_to_write;
2095 		}
2096 	} while (nilfs_sc_cstage_get(sci) != NILFS_ST_DONE);
2097 
2098  out:
2099 	nilfs_segctor_drop_written_files(sci, nilfs);
2100 	return err;
2101 
2102  failed_to_write:
2103 	if (sci->sc_stage.flags & NILFS_CF_IFILE_STARTED)
2104 		nilfs_redirty_inodes(&sci->sc_dirty_files);
2105 
2106  failed:
2107 	if (nilfs_doing_gc())
2108 		nilfs_redirty_inodes(&sci->sc_gc_inodes);
2109 	nilfs_segctor_abort_construction(sci, nilfs, err);
2110 	goto out;
2111 }
2112 
2113 /**
2114  * nilfs_segctor_start_timer - set timer of background write
2115  * @sci: nilfs_sc_info
2116  *
2117  * If the timer has already been set, it ignores the new request.
2118  * This function MUST be called within a section locking the segment
2119  * semaphore.
2120  */
2121 static void nilfs_segctor_start_timer(struct nilfs_sc_info *sci)
2122 {
2123 	spin_lock(&sci->sc_state_lock);
2124 	if (!(sci->sc_state & NILFS_SEGCTOR_COMMIT)) {
2125 		sci->sc_timer.expires = jiffies + sci->sc_interval;
2126 		add_timer(&sci->sc_timer);
2127 		sci->sc_state |= NILFS_SEGCTOR_COMMIT;
2128 	}
2129 	spin_unlock(&sci->sc_state_lock);
2130 }
2131 
2132 static void nilfs_segctor_do_flush(struct nilfs_sc_info *sci, int bn)
2133 {
2134 	spin_lock(&sci->sc_state_lock);
2135 	if (!(sci->sc_flush_request & BIT(bn))) {
2136 		unsigned long prev_req = sci->sc_flush_request;
2137 
2138 		sci->sc_flush_request |= BIT(bn);
2139 		if (!prev_req)
2140 			wake_up(&sci->sc_wait_daemon);
2141 	}
2142 	spin_unlock(&sci->sc_state_lock);
2143 }
2144 
2145 /**
2146  * nilfs_flush_segment - trigger a segment construction for resource control
2147  * @sb: super block
2148  * @ino: inode number of the file to be flushed out.
2149  */
2150 void nilfs_flush_segment(struct super_block *sb, ino_t ino)
2151 {
2152 	struct the_nilfs *nilfs = sb->s_fs_info;
2153 	struct nilfs_sc_info *sci = nilfs->ns_writer;
2154 
2155 	if (!sci || nilfs_doing_construction())
2156 		return;
2157 	nilfs_segctor_do_flush(sci, NILFS_MDT_INODE(sb, ino) ? ino : 0);
2158 					/* assign bit 0 to data files */
2159 }
2160 
2161 struct nilfs_segctor_wait_request {
2162 	wait_queue_entry_t	wq;
2163 	__u32		seq;
2164 	int		err;
2165 	atomic_t	done;
2166 };
2167 
2168 static int nilfs_segctor_sync(struct nilfs_sc_info *sci)
2169 {
2170 	struct nilfs_segctor_wait_request wait_req;
2171 	int err = 0;
2172 
2173 	spin_lock(&sci->sc_state_lock);
2174 	init_wait(&wait_req.wq);
2175 	wait_req.err = 0;
2176 	atomic_set(&wait_req.done, 0);
2177 	wait_req.seq = ++sci->sc_seq_request;
2178 	spin_unlock(&sci->sc_state_lock);
2179 
2180 	init_waitqueue_entry(&wait_req.wq, current);
2181 	add_wait_queue(&sci->sc_wait_request, &wait_req.wq);
2182 	set_current_state(TASK_INTERRUPTIBLE);
2183 	wake_up(&sci->sc_wait_daemon);
2184 
2185 	for (;;) {
2186 		if (atomic_read(&wait_req.done)) {
2187 			err = wait_req.err;
2188 			break;
2189 		}
2190 		if (!signal_pending(current)) {
2191 			schedule();
2192 			continue;
2193 		}
2194 		err = -ERESTARTSYS;
2195 		break;
2196 	}
2197 	finish_wait(&sci->sc_wait_request, &wait_req.wq);
2198 	return err;
2199 }
2200 
2201 static void nilfs_segctor_wakeup(struct nilfs_sc_info *sci, int err)
2202 {
2203 	struct nilfs_segctor_wait_request *wrq, *n;
2204 	unsigned long flags;
2205 
2206 	spin_lock_irqsave(&sci->sc_wait_request.lock, flags);
2207 	list_for_each_entry_safe(wrq, n, &sci->sc_wait_request.head, wq.entry) {
2208 		if (!atomic_read(&wrq->done) &&
2209 		    nilfs_cnt32_ge(sci->sc_seq_done, wrq->seq)) {
2210 			wrq->err = err;
2211 			atomic_set(&wrq->done, 1);
2212 		}
2213 		if (atomic_read(&wrq->done)) {
2214 			wrq->wq.func(&wrq->wq,
2215 				     TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
2216 				     0, NULL);
2217 		}
2218 	}
2219 	spin_unlock_irqrestore(&sci->sc_wait_request.lock, flags);
2220 }
2221 
2222 /**
2223  * nilfs_construct_segment - construct a logical segment
2224  * @sb: super block
2225  *
2226  * Return Value: On success, 0 is returned. On errors, one of the following
2227  * negative error code is returned.
2228  *
2229  * %-EROFS - Read only filesystem.
2230  *
2231  * %-EIO - I/O error
2232  *
2233  * %-ENOSPC - No space left on device (only in a panic state).
2234  *
2235  * %-ERESTARTSYS - Interrupted.
2236  *
2237  * %-ENOMEM - Insufficient memory available.
2238  */
2239 int nilfs_construct_segment(struct super_block *sb)
2240 {
2241 	struct the_nilfs *nilfs = sb->s_fs_info;
2242 	struct nilfs_sc_info *sci = nilfs->ns_writer;
2243 	struct nilfs_transaction_info *ti;
2244 
2245 	if (sb_rdonly(sb) || unlikely(!sci))
2246 		return -EROFS;
2247 
2248 	/* A call inside transactions causes a deadlock. */
2249 	BUG_ON((ti = current->journal_info) && ti->ti_magic == NILFS_TI_MAGIC);
2250 
2251 	return nilfs_segctor_sync(sci);
2252 }
2253 
2254 /**
2255  * nilfs_construct_dsync_segment - construct a data-only logical segment
2256  * @sb: super block
2257  * @inode: inode whose data blocks should be written out
2258  * @start: start byte offset
2259  * @end: end byte offset (inclusive)
2260  *
2261  * Return Value: On success, 0 is returned. On errors, one of the following
2262  * negative error code is returned.
2263  *
2264  * %-EROFS - Read only filesystem.
2265  *
2266  * %-EIO - I/O error
2267  *
2268  * %-ENOSPC - No space left on device (only in a panic state).
2269  *
2270  * %-ERESTARTSYS - Interrupted.
2271  *
2272  * %-ENOMEM - Insufficient memory available.
2273  */
2274 int nilfs_construct_dsync_segment(struct super_block *sb, struct inode *inode,
2275 				  loff_t start, loff_t end)
2276 {
2277 	struct the_nilfs *nilfs = sb->s_fs_info;
2278 	struct nilfs_sc_info *sci = nilfs->ns_writer;
2279 	struct nilfs_inode_info *ii;
2280 	struct nilfs_transaction_info ti;
2281 	int err = 0;
2282 
2283 	if (sb_rdonly(sb) || unlikely(!sci))
2284 		return -EROFS;
2285 
2286 	nilfs_transaction_lock(sb, &ti, 0);
2287 
2288 	ii = NILFS_I(inode);
2289 	if (test_bit(NILFS_I_INODE_SYNC, &ii->i_state) ||
2290 	    nilfs_test_opt(nilfs, STRICT_ORDER) ||
2291 	    test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags) ||
2292 	    nilfs_discontinued(nilfs)) {
2293 		nilfs_transaction_unlock(sb);
2294 		err = nilfs_segctor_sync(sci);
2295 		return err;
2296 	}
2297 
2298 	spin_lock(&nilfs->ns_inode_lock);
2299 	if (!test_bit(NILFS_I_QUEUED, &ii->i_state) &&
2300 	    !test_bit(NILFS_I_BUSY, &ii->i_state)) {
2301 		spin_unlock(&nilfs->ns_inode_lock);
2302 		nilfs_transaction_unlock(sb);
2303 		return 0;
2304 	}
2305 	spin_unlock(&nilfs->ns_inode_lock);
2306 	sci->sc_dsync_inode = ii;
2307 	sci->sc_dsync_start = start;
2308 	sci->sc_dsync_end = end;
2309 
2310 	err = nilfs_segctor_do_construct(sci, SC_LSEG_DSYNC);
2311 	if (!err)
2312 		nilfs->ns_flushed_device = 0;
2313 
2314 	nilfs_transaction_unlock(sb);
2315 	return err;
2316 }
2317 
2318 #define FLUSH_FILE_BIT	(0x1) /* data file only */
2319 #define FLUSH_DAT_BIT	BIT(NILFS_DAT_INO) /* DAT only */
2320 
2321 /**
2322  * nilfs_segctor_accept - record accepted sequence count of log-write requests
2323  * @sci: segment constructor object
2324  */
2325 static void nilfs_segctor_accept(struct nilfs_sc_info *sci)
2326 {
2327 	spin_lock(&sci->sc_state_lock);
2328 	sci->sc_seq_accepted = sci->sc_seq_request;
2329 	spin_unlock(&sci->sc_state_lock);
2330 	del_timer_sync(&sci->sc_timer);
2331 }
2332 
2333 /**
2334  * nilfs_segctor_notify - notify the result of request to caller threads
2335  * @sci: segment constructor object
2336  * @mode: mode of log forming
2337  * @err: error code to be notified
2338  */
2339 static void nilfs_segctor_notify(struct nilfs_sc_info *sci, int mode, int err)
2340 {
2341 	/* Clear requests (even when the construction failed) */
2342 	spin_lock(&sci->sc_state_lock);
2343 
2344 	if (mode == SC_LSEG_SR) {
2345 		sci->sc_state &= ~NILFS_SEGCTOR_COMMIT;
2346 		sci->sc_seq_done = sci->sc_seq_accepted;
2347 		nilfs_segctor_wakeup(sci, err);
2348 		sci->sc_flush_request = 0;
2349 	} else {
2350 		if (mode == SC_FLUSH_FILE)
2351 			sci->sc_flush_request &= ~FLUSH_FILE_BIT;
2352 		else if (mode == SC_FLUSH_DAT)
2353 			sci->sc_flush_request &= ~FLUSH_DAT_BIT;
2354 
2355 		/* re-enable timer if checkpoint creation was not done */
2356 		if ((sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
2357 		    time_before(jiffies, sci->sc_timer.expires))
2358 			add_timer(&sci->sc_timer);
2359 	}
2360 	spin_unlock(&sci->sc_state_lock);
2361 }
2362 
2363 /**
2364  * nilfs_segctor_construct - form logs and write them to disk
2365  * @sci: segment constructor object
2366  * @mode: mode of log forming
2367  */
2368 static int nilfs_segctor_construct(struct nilfs_sc_info *sci, int mode)
2369 {
2370 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2371 	struct nilfs_super_block **sbp;
2372 	int err = 0;
2373 
2374 	nilfs_segctor_accept(sci);
2375 
2376 	if (nilfs_discontinued(nilfs))
2377 		mode = SC_LSEG_SR;
2378 	if (!nilfs_segctor_confirm(sci))
2379 		err = nilfs_segctor_do_construct(sci, mode);
2380 
2381 	if (likely(!err)) {
2382 		if (mode != SC_FLUSH_DAT)
2383 			atomic_set(&nilfs->ns_ndirtyblks, 0);
2384 		if (test_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags) &&
2385 		    nilfs_discontinued(nilfs)) {
2386 			down_write(&nilfs->ns_sem);
2387 			err = -EIO;
2388 			sbp = nilfs_prepare_super(sci->sc_super,
2389 						  nilfs_sb_will_flip(nilfs));
2390 			if (likely(sbp)) {
2391 				nilfs_set_log_cursor(sbp[0], nilfs);
2392 				err = nilfs_commit_super(sci->sc_super,
2393 							 NILFS_SB_COMMIT);
2394 			}
2395 			up_write(&nilfs->ns_sem);
2396 		}
2397 	}
2398 
2399 	nilfs_segctor_notify(sci, mode, err);
2400 	return err;
2401 }
2402 
2403 static void nilfs_construction_timeout(struct timer_list *t)
2404 {
2405 	struct nilfs_sc_info *sci = from_timer(sci, t, sc_timer);
2406 
2407 	wake_up_process(sci->sc_timer_task);
2408 }
2409 
2410 static void
2411 nilfs_remove_written_gcinodes(struct the_nilfs *nilfs, struct list_head *head)
2412 {
2413 	struct nilfs_inode_info *ii, *n;
2414 
2415 	list_for_each_entry_safe(ii, n, head, i_dirty) {
2416 		if (!test_bit(NILFS_I_UPDATED, &ii->i_state))
2417 			continue;
2418 		list_del_init(&ii->i_dirty);
2419 		truncate_inode_pages(&ii->vfs_inode.i_data, 0);
2420 		nilfs_btnode_cache_clear(ii->i_assoc_inode->i_mapping);
2421 		iput(&ii->vfs_inode);
2422 	}
2423 }
2424 
2425 int nilfs_clean_segments(struct super_block *sb, struct nilfs_argv *argv,
2426 			 void **kbufs)
2427 {
2428 	struct the_nilfs *nilfs = sb->s_fs_info;
2429 	struct nilfs_sc_info *sci = nilfs->ns_writer;
2430 	struct nilfs_transaction_info ti;
2431 	int err;
2432 
2433 	if (unlikely(!sci))
2434 		return -EROFS;
2435 
2436 	nilfs_transaction_lock(sb, &ti, 1);
2437 
2438 	err = nilfs_mdt_save_to_shadow_map(nilfs->ns_dat);
2439 	if (unlikely(err))
2440 		goto out_unlock;
2441 
2442 	err = nilfs_ioctl_prepare_clean_segments(nilfs, argv, kbufs);
2443 	if (unlikely(err)) {
2444 		nilfs_mdt_restore_from_shadow_map(nilfs->ns_dat);
2445 		goto out_unlock;
2446 	}
2447 
2448 	sci->sc_freesegs = kbufs[4];
2449 	sci->sc_nfreesegs = argv[4].v_nmembs;
2450 	list_splice_tail_init(&nilfs->ns_gc_inodes, &sci->sc_gc_inodes);
2451 
2452 	for (;;) {
2453 		err = nilfs_segctor_construct(sci, SC_LSEG_SR);
2454 		nilfs_remove_written_gcinodes(nilfs, &sci->sc_gc_inodes);
2455 
2456 		if (likely(!err))
2457 			break;
2458 
2459 		nilfs_warn(sb, "error %d cleaning segments", err);
2460 		set_current_state(TASK_INTERRUPTIBLE);
2461 		schedule_timeout(sci->sc_interval);
2462 	}
2463 	if (nilfs_test_opt(nilfs, DISCARD)) {
2464 		int ret = nilfs_discard_segments(nilfs, sci->sc_freesegs,
2465 						 sci->sc_nfreesegs);
2466 		if (ret) {
2467 			nilfs_warn(sb,
2468 				   "error %d on discard request, turning discards off for the device",
2469 				   ret);
2470 			nilfs_clear_opt(nilfs, DISCARD);
2471 		}
2472 	}
2473 
2474  out_unlock:
2475 	sci->sc_freesegs = NULL;
2476 	sci->sc_nfreesegs = 0;
2477 	nilfs_mdt_clear_shadow_map(nilfs->ns_dat);
2478 	nilfs_transaction_unlock(sb);
2479 	return err;
2480 }
2481 
2482 static void nilfs_segctor_thread_construct(struct nilfs_sc_info *sci, int mode)
2483 {
2484 	struct nilfs_transaction_info ti;
2485 
2486 	nilfs_transaction_lock(sci->sc_super, &ti, 0);
2487 	nilfs_segctor_construct(sci, mode);
2488 
2489 	/*
2490 	 * Unclosed segment should be retried.  We do this using sc_timer.
2491 	 * Timeout of sc_timer will invoke complete construction which leads
2492 	 * to close the current logical segment.
2493 	 */
2494 	if (test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags))
2495 		nilfs_segctor_start_timer(sci);
2496 
2497 	nilfs_transaction_unlock(sci->sc_super);
2498 }
2499 
2500 static void nilfs_segctor_do_immediate_flush(struct nilfs_sc_info *sci)
2501 {
2502 	int mode = 0;
2503 
2504 	spin_lock(&sci->sc_state_lock);
2505 	mode = (sci->sc_flush_request & FLUSH_DAT_BIT) ?
2506 		SC_FLUSH_DAT : SC_FLUSH_FILE;
2507 	spin_unlock(&sci->sc_state_lock);
2508 
2509 	if (mode) {
2510 		nilfs_segctor_do_construct(sci, mode);
2511 
2512 		spin_lock(&sci->sc_state_lock);
2513 		sci->sc_flush_request &= (mode == SC_FLUSH_FILE) ?
2514 			~FLUSH_FILE_BIT : ~FLUSH_DAT_BIT;
2515 		spin_unlock(&sci->sc_state_lock);
2516 	}
2517 	clear_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags);
2518 }
2519 
2520 static int nilfs_segctor_flush_mode(struct nilfs_sc_info *sci)
2521 {
2522 	if (!test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags) ||
2523 	    time_before(jiffies, sci->sc_lseg_stime + sci->sc_mjcp_freq)) {
2524 		if (!(sci->sc_flush_request & ~FLUSH_FILE_BIT))
2525 			return SC_FLUSH_FILE;
2526 		else if (!(sci->sc_flush_request & ~FLUSH_DAT_BIT))
2527 			return SC_FLUSH_DAT;
2528 	}
2529 	return SC_LSEG_SR;
2530 }
2531 
2532 /**
2533  * nilfs_segctor_thread - main loop of the segment constructor thread.
2534  * @arg: pointer to a struct nilfs_sc_info.
2535  *
2536  * nilfs_segctor_thread() initializes a timer and serves as a daemon
2537  * to execute segment constructions.
2538  */
2539 static int nilfs_segctor_thread(void *arg)
2540 {
2541 	struct nilfs_sc_info *sci = (struct nilfs_sc_info *)arg;
2542 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2543 	int timeout = 0;
2544 
2545 	sci->sc_timer_task = current;
2546 
2547 	/* start sync. */
2548 	sci->sc_task = current;
2549 	wake_up(&sci->sc_wait_task); /* for nilfs_segctor_start_thread() */
2550 	nilfs_info(sci->sc_super,
2551 		   "segctord starting. Construction interval = %lu seconds, CP frequency < %lu seconds",
2552 		   sci->sc_interval / HZ, sci->sc_mjcp_freq / HZ);
2553 
2554 	spin_lock(&sci->sc_state_lock);
2555  loop:
2556 	for (;;) {
2557 		int mode;
2558 
2559 		if (sci->sc_state & NILFS_SEGCTOR_QUIT)
2560 			goto end_thread;
2561 
2562 		if (timeout || sci->sc_seq_request != sci->sc_seq_done)
2563 			mode = SC_LSEG_SR;
2564 		else if (sci->sc_flush_request)
2565 			mode = nilfs_segctor_flush_mode(sci);
2566 		else
2567 			break;
2568 
2569 		spin_unlock(&sci->sc_state_lock);
2570 		nilfs_segctor_thread_construct(sci, mode);
2571 		spin_lock(&sci->sc_state_lock);
2572 		timeout = 0;
2573 	}
2574 
2575 
2576 	if (freezing(current)) {
2577 		spin_unlock(&sci->sc_state_lock);
2578 		try_to_freeze();
2579 		spin_lock(&sci->sc_state_lock);
2580 	} else {
2581 		DEFINE_WAIT(wait);
2582 		int should_sleep = 1;
2583 
2584 		prepare_to_wait(&sci->sc_wait_daemon, &wait,
2585 				TASK_INTERRUPTIBLE);
2586 
2587 		if (sci->sc_seq_request != sci->sc_seq_done)
2588 			should_sleep = 0;
2589 		else if (sci->sc_flush_request)
2590 			should_sleep = 0;
2591 		else if (sci->sc_state & NILFS_SEGCTOR_COMMIT)
2592 			should_sleep = time_before(jiffies,
2593 					sci->sc_timer.expires);
2594 
2595 		if (should_sleep) {
2596 			spin_unlock(&sci->sc_state_lock);
2597 			schedule();
2598 			spin_lock(&sci->sc_state_lock);
2599 		}
2600 		finish_wait(&sci->sc_wait_daemon, &wait);
2601 		timeout = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
2602 			   time_after_eq(jiffies, sci->sc_timer.expires));
2603 
2604 		if (nilfs_sb_dirty(nilfs) && nilfs_sb_need_update(nilfs))
2605 			set_nilfs_discontinued(nilfs);
2606 	}
2607 	goto loop;
2608 
2609  end_thread:
2610 	spin_unlock(&sci->sc_state_lock);
2611 
2612 	/* end sync. */
2613 	sci->sc_task = NULL;
2614 	wake_up(&sci->sc_wait_task); /* for nilfs_segctor_kill_thread() */
2615 	return 0;
2616 }
2617 
2618 static int nilfs_segctor_start_thread(struct nilfs_sc_info *sci)
2619 {
2620 	struct task_struct *t;
2621 
2622 	t = kthread_run(nilfs_segctor_thread, sci, "segctord");
2623 	if (IS_ERR(t)) {
2624 		int err = PTR_ERR(t);
2625 
2626 		nilfs_err(sci->sc_super, "error %d creating segctord thread",
2627 			  err);
2628 		return err;
2629 	}
2630 	wait_event(sci->sc_wait_task, sci->sc_task != NULL);
2631 	return 0;
2632 }
2633 
2634 static void nilfs_segctor_kill_thread(struct nilfs_sc_info *sci)
2635 	__acquires(&sci->sc_state_lock)
2636 	__releases(&sci->sc_state_lock)
2637 {
2638 	sci->sc_state |= NILFS_SEGCTOR_QUIT;
2639 
2640 	while (sci->sc_task) {
2641 		wake_up(&sci->sc_wait_daemon);
2642 		spin_unlock(&sci->sc_state_lock);
2643 		wait_event(sci->sc_wait_task, sci->sc_task == NULL);
2644 		spin_lock(&sci->sc_state_lock);
2645 	}
2646 }
2647 
2648 /*
2649  * Setup & clean-up functions
2650  */
2651 static struct nilfs_sc_info *nilfs_segctor_new(struct super_block *sb,
2652 					       struct nilfs_root *root)
2653 {
2654 	struct the_nilfs *nilfs = sb->s_fs_info;
2655 	struct nilfs_sc_info *sci;
2656 
2657 	sci = kzalloc(sizeof(*sci), GFP_KERNEL);
2658 	if (!sci)
2659 		return NULL;
2660 
2661 	sci->sc_super = sb;
2662 
2663 	nilfs_get_root(root);
2664 	sci->sc_root = root;
2665 
2666 	init_waitqueue_head(&sci->sc_wait_request);
2667 	init_waitqueue_head(&sci->sc_wait_daemon);
2668 	init_waitqueue_head(&sci->sc_wait_task);
2669 	spin_lock_init(&sci->sc_state_lock);
2670 	INIT_LIST_HEAD(&sci->sc_dirty_files);
2671 	INIT_LIST_HEAD(&sci->sc_segbufs);
2672 	INIT_LIST_HEAD(&sci->sc_write_logs);
2673 	INIT_LIST_HEAD(&sci->sc_gc_inodes);
2674 	INIT_LIST_HEAD(&sci->sc_iput_queue);
2675 	INIT_WORK(&sci->sc_iput_work, nilfs_iput_work_func);
2676 	timer_setup(&sci->sc_timer, nilfs_construction_timeout, 0);
2677 
2678 	sci->sc_interval = HZ * NILFS_SC_DEFAULT_TIMEOUT;
2679 	sci->sc_mjcp_freq = HZ * NILFS_SC_DEFAULT_SR_FREQ;
2680 	sci->sc_watermark = NILFS_SC_DEFAULT_WATERMARK;
2681 
2682 	if (nilfs->ns_interval)
2683 		sci->sc_interval = HZ * nilfs->ns_interval;
2684 	if (nilfs->ns_watermark)
2685 		sci->sc_watermark = nilfs->ns_watermark;
2686 	return sci;
2687 }
2688 
2689 static void nilfs_segctor_write_out(struct nilfs_sc_info *sci)
2690 {
2691 	int ret, retrycount = NILFS_SC_CLEANUP_RETRY;
2692 
2693 	/*
2694 	 * The segctord thread was stopped and its timer was removed.
2695 	 * But some tasks remain.
2696 	 */
2697 	do {
2698 		struct nilfs_transaction_info ti;
2699 
2700 		nilfs_transaction_lock(sci->sc_super, &ti, 0);
2701 		ret = nilfs_segctor_construct(sci, SC_LSEG_SR);
2702 		nilfs_transaction_unlock(sci->sc_super);
2703 
2704 		flush_work(&sci->sc_iput_work);
2705 
2706 	} while (ret && retrycount-- > 0);
2707 }
2708 
2709 /**
2710  * nilfs_segctor_destroy - destroy the segment constructor.
2711  * @sci: nilfs_sc_info
2712  *
2713  * nilfs_segctor_destroy() kills the segctord thread and frees
2714  * the nilfs_sc_info struct.
2715  * Caller must hold the segment semaphore.
2716  */
2717 static void nilfs_segctor_destroy(struct nilfs_sc_info *sci)
2718 {
2719 	struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2720 	int flag;
2721 
2722 	up_write(&nilfs->ns_segctor_sem);
2723 
2724 	spin_lock(&sci->sc_state_lock);
2725 	nilfs_segctor_kill_thread(sci);
2726 	flag = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) || sci->sc_flush_request
2727 		|| sci->sc_seq_request != sci->sc_seq_done);
2728 	spin_unlock(&sci->sc_state_lock);
2729 
2730 	if (flush_work(&sci->sc_iput_work))
2731 		flag = true;
2732 
2733 	if (flag || !nilfs_segctor_confirm(sci))
2734 		nilfs_segctor_write_out(sci);
2735 
2736 	if (!list_empty(&sci->sc_dirty_files)) {
2737 		nilfs_warn(sci->sc_super,
2738 			   "disposed unprocessed dirty file(s) when stopping log writer");
2739 		nilfs_dispose_list(nilfs, &sci->sc_dirty_files, 1);
2740 	}
2741 
2742 	if (!list_empty(&sci->sc_iput_queue)) {
2743 		nilfs_warn(sci->sc_super,
2744 			   "disposed unprocessed inode(s) in iput queue when stopping log writer");
2745 		nilfs_dispose_list(nilfs, &sci->sc_iput_queue, 1);
2746 	}
2747 
2748 	WARN_ON(!list_empty(&sci->sc_segbufs));
2749 	WARN_ON(!list_empty(&sci->sc_write_logs));
2750 
2751 	nilfs_put_root(sci->sc_root);
2752 
2753 	down_write(&nilfs->ns_segctor_sem);
2754 
2755 	timer_shutdown_sync(&sci->sc_timer);
2756 	kfree(sci);
2757 }
2758 
2759 /**
2760  * nilfs_attach_log_writer - attach log writer
2761  * @sb: super block instance
2762  * @root: root object of the current filesystem tree
2763  *
2764  * This allocates a log writer object, initializes it, and starts the
2765  * log writer.
2766  *
2767  * Return Value: On success, 0 is returned. On error, one of the following
2768  * negative error code is returned.
2769  *
2770  * %-ENOMEM - Insufficient memory available.
2771  */
2772 int nilfs_attach_log_writer(struct super_block *sb, struct nilfs_root *root)
2773 {
2774 	struct the_nilfs *nilfs = sb->s_fs_info;
2775 	int err;
2776 
2777 	if (nilfs->ns_writer) {
2778 		/*
2779 		 * This happens if the filesystem is made read-only by
2780 		 * __nilfs_error or nilfs_remount and then remounted
2781 		 * read/write.  In these cases, reuse the existing
2782 		 * writer.
2783 		 */
2784 		return 0;
2785 	}
2786 
2787 	nilfs->ns_writer = nilfs_segctor_new(sb, root);
2788 	if (!nilfs->ns_writer)
2789 		return -ENOMEM;
2790 
2791 	inode_attach_wb(nilfs->ns_bdev->bd_inode, NULL);
2792 
2793 	err = nilfs_segctor_start_thread(nilfs->ns_writer);
2794 	if (unlikely(err))
2795 		nilfs_detach_log_writer(sb);
2796 
2797 	return err;
2798 }
2799 
2800 /**
2801  * nilfs_detach_log_writer - destroy log writer
2802  * @sb: super block instance
2803  *
2804  * This kills log writer daemon, frees the log writer object, and
2805  * destroys list of dirty files.
2806  */
2807 void nilfs_detach_log_writer(struct super_block *sb)
2808 {
2809 	struct the_nilfs *nilfs = sb->s_fs_info;
2810 	LIST_HEAD(garbage_list);
2811 
2812 	down_write(&nilfs->ns_segctor_sem);
2813 	if (nilfs->ns_writer) {
2814 		nilfs_segctor_destroy(nilfs->ns_writer);
2815 		nilfs->ns_writer = NULL;
2816 	}
2817 
2818 	/* Force to free the list of dirty files */
2819 	spin_lock(&nilfs->ns_inode_lock);
2820 	if (!list_empty(&nilfs->ns_dirty_files)) {
2821 		list_splice_init(&nilfs->ns_dirty_files, &garbage_list);
2822 		nilfs_warn(sb,
2823 			   "disposed unprocessed dirty file(s) when detaching log writer");
2824 	}
2825 	spin_unlock(&nilfs->ns_inode_lock);
2826 	up_write(&nilfs->ns_segctor_sem);
2827 
2828 	nilfs_dispose_list(nilfs, &garbage_list, 1);
2829 }
2830