1 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
2 From: Changwei Ge <ge.changwei@h3c.com>
3 Date: Wed, 31 Jan 2018 16:15:06 -0800
4 Subject: [PATCH] ocfs2: try to reuse extent block in dealloc without
7 Content-Type: text/plain; charset=UTF-8
8 Content-Transfer-Encoding: 8bit
10 A crash issue was reported by John Lightsey with a call trace as follows:
12 ocfs2_split_extent+0x1ad3/0x1b40 [ocfs2]
13 ocfs2_change_extent_flag+0x33a/0x470 [ocfs2]
14 ocfs2_mark_extent_written+0x172/0x220 [ocfs2]
15 ocfs2_dio_end_io+0x62d/0x910 [ocfs2]
16 dio_complete+0x19a/0x1a0
17 do_blockdev_direct_IO+0x19dd/0x1eb0
18 __blockdev_direct_IO+0x43/0x50
19 ocfs2_direct_IO+0x8f/0xa0 [ocfs2]
20 generic_file_direct_write+0xb2/0x170
21 __generic_file_write_iter+0xc3/0x1b0
22 ocfs2_file_write_iter+0x4bb/0xca0 [ocfs2]
26 system_call_fastpath+0x16/0x75
28 The BUG code told that extent tree wants to grow but no metadata was
29 reserved ahead of time. From my investigation into this issue, the root
30 cause it that although enough metadata is not reserved, there should be
31 enough for following use. Rightmost extent is merged into its left one
32 due to a certain times of marking extent written. Because during
33 marking extent written, we got many physically continuous extents. At
34 last, an empty extent showed up and the rightmost path is removed from
37 Add a new mechanism to reuse extent block cached in dealloc which were
38 just unlinked from extent tree to solve this crash issue.
40 Criteria is that during marking extents *written*, if extent rotation
41 and merging results in unlinking extent with growing extent tree later
42 without any metadata reserved ahead of time, try to reuse those extents
43 in dealloc in which deleted extents are cached.
45 Also, this patch addresses the issue John reported that ::dw_zero_count
46 is not calculated properly.
48 After applying this patch, the issue John reported was gone. Thanks for
49 the reproducer provided by John. And this patch has passed
50 ocfs2-test(29 cases) suite running by New H3C Group.
52 [ge.changwei@h3c.com: fix static checker warnning]
53 Link: http://lkml.kernel.org/r/63ADC13FD55D6546B7DECE290D39E373F29196AE@H3CMLB12-EX.srv.huawei-3com.com
54 [akpm@linux-foundation.org: brelse(NULL) is legal]
55 Link: http://lkml.kernel.org/r/1515479070-32653-2-git-send-email-ge.changwei@h3c.com
56 Signed-off-by: Changwei Ge <ge.changwei@h3c.com>
57 Reported-by: John Lightsey <john@nixnuts.net>
58 Tested-by: John Lightsey <john@nixnuts.net>
59 Cc: Joel Becker <jlbec@evilplan.org>
60 Cc: Joseph Qi <jiangqi903@gmail.com>
61 Cc: Junxiao Bi <junxiao.bi@oracle.com>
62 Cc: Dan Carpenter <dan.carpenter@oracle.com>
63 Cc: Mark Fasheh <mfasheh@versity.com>
64 Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
65 Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
66 (cherry picked from commit 71a36944042b7d9dd71f6a5d1c5ea1c2353b5d42)
67 Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
69 fs/ocfs2/alloc.c | 206 ++++++++++++++++++++++++++++++++++++++++++++---
70 fs/ocfs2/alloc.h | 1 +
71 fs/ocfs2/aops.c | 6 ++
72 3 files changed, 203 insertions(+), 10 deletions(-)
74 diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c
75 index ab5105f9767e..2f2c76193f54 100644
76 --- a/fs/ocfs2/alloc.c
77 +++ b/fs/ocfs2/alloc.c
78 @@ -165,6 +165,13 @@ static int ocfs2_dinode_insert_check(struct ocfs2_extent_tree *et,
79 struct ocfs2_extent_rec *rec);
80 static int ocfs2_dinode_sanity_check(struct ocfs2_extent_tree *et);
81 static void ocfs2_dinode_fill_root_el(struct ocfs2_extent_tree *et);
83 +static int ocfs2_reuse_blk_from_dealloc(handle_t *handle,
84 + struct ocfs2_extent_tree *et,
85 + struct buffer_head **new_eb_bh,
86 + int blk_wanted, int *blk_given);
87 +static int ocfs2_is_dealloc_empty(struct ocfs2_extent_tree *et);
89 static const struct ocfs2_extent_tree_operations ocfs2_dinode_et_ops = {
90 .eo_set_last_eb_blk = ocfs2_dinode_set_last_eb_blk,
91 .eo_get_last_eb_blk = ocfs2_dinode_get_last_eb_blk,
92 @@ -448,6 +455,7 @@ static void __ocfs2_init_extent_tree(struct ocfs2_extent_tree *et,
94 obj = (void *)bh->b_data;
96 + et->et_dealloc = NULL;
98 et->et_ops->eo_fill_root_el(et);
99 if (!et->et_ops->eo_fill_max_leaf_clusters)
100 @@ -1158,7 +1166,7 @@ static int ocfs2_add_branch(handle_t *handle,
101 struct buffer_head **last_eb_bh,
102 struct ocfs2_alloc_context *meta_ac)
104 - int status, new_blocks, i;
105 + int status, new_blocks, i, block_given = 0;
106 u64 next_blkno, new_last_eb_blk;
107 struct buffer_head *bh;
108 struct buffer_head **new_eb_bhs = NULL;
109 @@ -1213,11 +1221,31 @@ static int ocfs2_add_branch(handle_t *handle,
113 - status = ocfs2_create_new_meta_bhs(handle, et, new_blocks,
114 - meta_ac, new_eb_bhs);
116 - mlog_errno(status);
118 + /* Firstyly, try to reuse dealloc since we have already estimated how
119 + * many extent blocks we may use.
121 + if (!ocfs2_is_dealloc_empty(et)) {
122 + status = ocfs2_reuse_blk_from_dealloc(handle, et,
123 + new_eb_bhs, new_blocks,
126 + mlog_errno(status);
131 + BUG_ON(block_given > new_blocks);
133 + if (block_given < new_blocks) {
135 + status = ocfs2_create_new_meta_bhs(handle, et,
136 + new_blocks - block_given,
138 + &new_eb_bhs[block_given]);
140 + mlog_errno(status);
145 /* Note: new_eb_bhs[new_blocks - 1] is the guy which will be
146 @@ -1340,15 +1368,25 @@ static int ocfs2_shift_tree_depth(handle_t *handle,
147 struct ocfs2_alloc_context *meta_ac,
148 struct buffer_head **ret_new_eb_bh)
151 + int status, i, block_given = 0;
153 struct buffer_head *new_eb_bh = NULL;
154 struct ocfs2_extent_block *eb;
155 struct ocfs2_extent_list *root_el;
156 struct ocfs2_extent_list *eb_el;
158 - status = ocfs2_create_new_meta_bhs(handle, et, 1, meta_ac,
160 + if (!ocfs2_is_dealloc_empty(et)) {
161 + status = ocfs2_reuse_blk_from_dealloc(handle, et,
164 + } else if (meta_ac) {
165 + status = ocfs2_create_new_meta_bhs(handle, et, 1, meta_ac,
175 @@ -1511,7 +1549,7 @@ static int ocfs2_grow_tree(handle_t *handle, struct ocfs2_extent_tree *et,
176 int depth = le16_to_cpu(el->l_tree_depth);
177 struct buffer_head *bh = NULL;
179 - BUG_ON(meta_ac == NULL);
180 + BUG_ON(meta_ac == NULL && ocfs2_is_dealloc_empty(et));
182 shift = ocfs2_find_branch_target(et, &bh);
184 @@ -6585,6 +6623,154 @@ ocfs2_find_per_slot_free_list(int type,
188 +static struct ocfs2_per_slot_free_list *
189 +ocfs2_find_preferred_free_list(int type,
190 + int preferred_slot,
192 + struct ocfs2_cached_dealloc_ctxt *ctxt)
194 + struct ocfs2_per_slot_free_list *fl = ctxt->c_first_suballocator;
197 + if (fl->f_inode_type == type && fl->f_slot == preferred_slot) {
198 + *real_slot = fl->f_slot;
202 + fl = fl->f_next_suballocator;
205 + /* If we can't find any free list matching preferred slot, just use
208 + fl = ctxt->c_first_suballocator;
209 + *real_slot = fl->f_slot;
214 +/* Return Value 1 indicates empty */
215 +static int ocfs2_is_dealloc_empty(struct ocfs2_extent_tree *et)
217 + struct ocfs2_per_slot_free_list *fl = NULL;
219 + if (!et->et_dealloc)
222 + fl = et->et_dealloc->c_first_suballocator;
232 +/* If extent was deleted from tree due to extent rotation and merging, and
233 + * no metadata is reserved ahead of time. Try to reuse some extents
234 + * just deleted. This is only used to reuse extent blocks.
235 + * It is supposed to find enough extent blocks in dealloc if our estimation
236 + * on metadata is accurate.
238 +static int ocfs2_reuse_blk_from_dealloc(handle_t *handle,
239 + struct ocfs2_extent_tree *et,
240 + struct buffer_head **new_eb_bh,
241 + int blk_wanted, int *blk_given)
243 + int i, status = 0, real_slot;
244 + struct ocfs2_cached_dealloc_ctxt *dealloc;
245 + struct ocfs2_per_slot_free_list *fl;
246 + struct ocfs2_cached_block_free *bf;
247 + struct ocfs2_extent_block *eb;
248 + struct ocfs2_super *osb =
249 + OCFS2_SB(ocfs2_metadata_cache_get_super(et->et_ci));
253 + /* If extent tree doesn't have a dealloc, this is not faulty. Just
254 + * tell upper caller dealloc can't provide any block and it should
255 + * ask for alloc to claim more space.
257 + dealloc = et->et_dealloc;
261 + for (i = 0; i < blk_wanted; i++) {
262 + /* Prefer to use local slot */
263 + fl = ocfs2_find_preferred_free_list(EXTENT_ALLOC_SYSTEM_INODE,
264 + osb->slot_num, &real_slot,
266 + /* If no more block can be reused, we should claim more
267 + * from alloc. Just return here normally.
275 + fl->f_first = bf->free_next;
277 + new_eb_bh[i] = sb_getblk(osb->sb, bf->free_blk);
278 + if (new_eb_bh[i] == NULL) {
280 + mlog_errno(status);
284 + mlog(0, "Reusing block(%llu) from "
285 + "dealloc(local slot:%d, real slot:%d)\n",
286 + bf->free_blk, osb->slot_num, real_slot);
288 + ocfs2_set_new_buffer_uptodate(et->et_ci, new_eb_bh[i]);
290 + status = ocfs2_journal_access_eb(handle, et->et_ci,
292 + OCFS2_JOURNAL_ACCESS_CREATE);
294 + mlog_errno(status);
298 + memset(new_eb_bh[i]->b_data, 0, osb->sb->s_blocksize);
299 + eb = (struct ocfs2_extent_block *) new_eb_bh[i]->b_data;
301 + /* We can't guarantee that buffer head is still cached, so
302 + * polutlate the extent block again.
304 + strcpy(eb->h_signature, OCFS2_EXTENT_BLOCK_SIGNATURE);
305 + eb->h_blkno = cpu_to_le64(bf->free_blk);
306 + eb->h_fs_generation = cpu_to_le32(osb->fs_generation);
307 + eb->h_suballoc_slot = cpu_to_le16(real_slot);
308 + eb->h_suballoc_loc = cpu_to_le64(bf->free_bg);
309 + eb->h_suballoc_bit = cpu_to_le16(bf->free_bit);
310 + eb->h_list.l_count =
311 + cpu_to_le16(ocfs2_extent_recs_per_eb(osb->sb));
313 + /* We'll also be dirtied by the caller, so
314 + * this isn't absolutely necessary.
316 + ocfs2_journal_dirty(handle, new_eb_bh[i]);
318 + if (!fl->f_first) {
319 + dealloc->c_first_suballocator = fl->f_next_suballocator;
328 + if (unlikely(status < 0)) {
329 + for (i = 0; i < blk_wanted; i++)
330 + brelse(new_eb_bh[i]);
336 int ocfs2_cache_block_dealloc(struct ocfs2_cached_dealloc_ctxt *ctxt,
337 int type, int slot, u64 suballoc,
338 u64 blkno, unsigned int bit)
339 diff --git a/fs/ocfs2/alloc.h b/fs/ocfs2/alloc.h
340 index 27b75cf32cfa..250bcacdf9e9 100644
341 --- a/fs/ocfs2/alloc.h
342 +++ b/fs/ocfs2/alloc.h
343 @@ -61,6 +61,7 @@ struct ocfs2_extent_tree {
344 ocfs2_journal_access_func et_root_journal_access;
346 unsigned int et_max_leaf_clusters;
347 + struct ocfs2_cached_dealloc_ctxt *et_dealloc;
351 diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
352 index 256986aca8df..e8e205bf2e41 100644
353 --- a/fs/ocfs2/aops.c
354 +++ b/fs/ocfs2/aops.c
355 @@ -2332,6 +2332,12 @@ static int ocfs2_dio_end_io_write(struct inode *inode,
357 ocfs2_init_dinode_extent_tree(&et, INODE_CACHE(inode), di_bh);
359 + /* Attach dealloc with extent tree in case that we may reuse extents
360 + * which are already unlinked from current extent tree due to extent
361 + * rotation and merging.
363 + et.et_dealloc = &dealloc;
365 ret = ocfs2_lock_allocators(inode, &et, 0, dwc->dw_zero_count*2,