-From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
-From: Changwei Ge <ge.changwei@h3c.com>
-Date: Wed, 31 Jan 2018 16:15:06 -0800
-Subject: [PATCH] ocfs2: try to reuse extent block in dealloc without
- meta_alloc
-MIME-Version: 1.0
-Content-Type: text/plain; charset=UTF-8
-Content-Transfer-Encoding: 8bit
-
-A crash issue was reported by John Lightsey with a call trace as follows:
-
- ocfs2_split_extent+0x1ad3/0x1b40 [ocfs2]
- ocfs2_change_extent_flag+0x33a/0x470 [ocfs2]
- ocfs2_mark_extent_written+0x172/0x220 [ocfs2]
- ocfs2_dio_end_io+0x62d/0x910 [ocfs2]
- dio_complete+0x19a/0x1a0
- do_blockdev_direct_IO+0x19dd/0x1eb0
- __blockdev_direct_IO+0x43/0x50
- ocfs2_direct_IO+0x8f/0xa0 [ocfs2]
- generic_file_direct_write+0xb2/0x170
- __generic_file_write_iter+0xc3/0x1b0
- ocfs2_file_write_iter+0x4bb/0xca0 [ocfs2]
- __vfs_write+0xae/0xf0
- vfs_write+0xb8/0x1b0
- SyS_write+0x4f/0xb0
- system_call_fastpath+0x16/0x75
-
-The BUG code told that extent tree wants to grow but no metadata was
-reserved ahead of time. From my investigation into this issue, the root
-cause it that although enough metadata is not reserved, there should be
-enough for following use. Rightmost extent is merged into its left one
-due to a certain times of marking extent written. Because during
-marking extent written, we got many physically continuous extents. At
-last, an empty extent showed up and the rightmost path is removed from
-extent tree.
-
-Add a new mechanism to reuse extent block cached in dealloc which were
-just unlinked from extent tree to solve this crash issue.
-
-Criteria is that during marking extents *written*, if extent rotation
-and merging results in unlinking extent with growing extent tree later
-without any metadata reserved ahead of time, try to reuse those extents
-in dealloc in which deleted extents are cached.
-
-Also, this patch addresses the issue John reported that ::dw_zero_count
-is not calculated properly.
-
-After applying this patch, the issue John reported was gone. Thanks for
-the reproducer provided by John. And this patch has passed
-ocfs2-test(29 cases) suite running by New H3C Group.
-
-[ge.changwei@h3c.com: fix static checker warnning]
- Link: http://lkml.kernel.org/r/63ADC13FD55D6546B7DECE290D39E373F29196AE@H3CMLB12-EX.srv.huawei-3com.com
-[akpm@linux-foundation.org: brelse(NULL) is legal]
-Link: http://lkml.kernel.org/r/1515479070-32653-2-git-send-email-ge.changwei@h3c.com
-Signed-off-by: Changwei Ge <ge.changwei@h3c.com>
-Reported-by: John Lightsey <john@nixnuts.net>
-Tested-by: John Lightsey <john@nixnuts.net>
-Cc: Joel Becker <jlbec@evilplan.org>
-Cc: Joseph Qi <jiangqi903@gmail.com>
-Cc: Junxiao Bi <junxiao.bi@oracle.com>
-Cc: Dan Carpenter <dan.carpenter@oracle.com>
-Cc: Mark Fasheh <mfasheh@versity.com>
-Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-(cherry picked from commit 71a36944042b7d9dd71f6a5d1c5ea1c2353b5d42)
-Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
----
- fs/ocfs2/alloc.c | 206 ++++++++++++++++++++++++++++++++++++++++++++++++++++---
- fs/ocfs2/alloc.h | 1 +
- fs/ocfs2/aops.c | 6 ++
- 3 files changed, 203 insertions(+), 10 deletions(-)
-
-diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c
-index 386aecce881d..9b5e7d8ba710 100644
---- a/fs/ocfs2/alloc.c
-+++ b/fs/ocfs2/alloc.c
-@@ -165,6 +165,13 @@ static int ocfs2_dinode_insert_check(struct ocfs2_extent_tree *et,
- struct ocfs2_extent_rec *rec);
- static int ocfs2_dinode_sanity_check(struct ocfs2_extent_tree *et);
- static void ocfs2_dinode_fill_root_el(struct ocfs2_extent_tree *et);
-+
-+static int ocfs2_reuse_blk_from_dealloc(handle_t *handle,
-+ struct ocfs2_extent_tree *et,
-+ struct buffer_head **new_eb_bh,
-+ int blk_wanted, int *blk_given);
-+static int ocfs2_is_dealloc_empty(struct ocfs2_extent_tree *et);
-+
- static const struct ocfs2_extent_tree_operations ocfs2_dinode_et_ops = {
- .eo_set_last_eb_blk = ocfs2_dinode_set_last_eb_blk,
- .eo_get_last_eb_blk = ocfs2_dinode_get_last_eb_blk,
-@@ -448,6 +455,7 @@ static void __ocfs2_init_extent_tree(struct ocfs2_extent_tree *et,
- if (!obj)
- obj = (void *)bh->b_data;
- et->et_object = obj;
-+ et->et_dealloc = NULL;
-
- et->et_ops->eo_fill_root_el(et);
- if (!et->et_ops->eo_fill_max_leaf_clusters)
-@@ -1159,7 +1167,7 @@ static int ocfs2_add_branch(handle_t *handle,
- struct buffer_head **last_eb_bh,
- struct ocfs2_alloc_context *meta_ac)
- {
-- int status, new_blocks, i;
-+ int status, new_blocks, i, block_given = 0;
- u64 next_blkno, new_last_eb_blk;
- struct buffer_head *bh;
- struct buffer_head **new_eb_bhs = NULL;
-@@ -1214,11 +1222,31 @@ static int ocfs2_add_branch(handle_t *handle,
- goto bail;
- }
-
-- status = ocfs2_create_new_meta_bhs(handle, et, new_blocks,
-- meta_ac, new_eb_bhs);
-- if (status < 0) {
-- mlog_errno(status);
-- goto bail;
-+ /* Firstyly, try to reuse dealloc since we have already estimated how
-+ * many extent blocks we may use.
-+ */
-+ if (!ocfs2_is_dealloc_empty(et)) {
-+ status = ocfs2_reuse_blk_from_dealloc(handle, et,
-+ new_eb_bhs, new_blocks,
-+ &block_given);
-+ if (status < 0) {
-+ mlog_errno(status);
-+ goto bail;
-+ }
-+ }
-+
-+ BUG_ON(block_given > new_blocks);
-+
-+ if (block_given < new_blocks) {
-+ BUG_ON(!meta_ac);
-+ status = ocfs2_create_new_meta_bhs(handle, et,
-+ new_blocks - block_given,
-+ meta_ac,
-+ &new_eb_bhs[block_given]);
-+ if (status < 0) {
-+ mlog_errno(status);
-+ goto bail;
-+ }
- }
-
- /* Note: new_eb_bhs[new_blocks - 1] is the guy which will be
-@@ -1341,15 +1369,25 @@ static int ocfs2_shift_tree_depth(handle_t *handle,
- struct ocfs2_alloc_context *meta_ac,
- struct buffer_head **ret_new_eb_bh)
- {
-- int status, i;
-+ int status, i, block_given = 0;
- u32 new_clusters;
- struct buffer_head *new_eb_bh = NULL;
- struct ocfs2_extent_block *eb;
- struct ocfs2_extent_list *root_el;
- struct ocfs2_extent_list *eb_el;
-
-- status = ocfs2_create_new_meta_bhs(handle, et, 1, meta_ac,
-- &new_eb_bh);
-+ if (!ocfs2_is_dealloc_empty(et)) {
-+ status = ocfs2_reuse_blk_from_dealloc(handle, et,
-+ &new_eb_bh, 1,
-+ &block_given);
-+ } else if (meta_ac) {
-+ status = ocfs2_create_new_meta_bhs(handle, et, 1, meta_ac,
-+ &new_eb_bh);
-+
-+ } else {
-+ BUG();
-+ }
-+
- if (status < 0) {
- mlog_errno(status);
- goto bail;
-@@ -1512,7 +1550,7 @@ static int ocfs2_grow_tree(handle_t *handle, struct ocfs2_extent_tree *et,
- int depth = le16_to_cpu(el->l_tree_depth);
- struct buffer_head *bh = NULL;
-
-- BUG_ON(meta_ac == NULL);
-+ BUG_ON(meta_ac == NULL && ocfs2_is_dealloc_empty(et));
-
- shift = ocfs2_find_branch_target(et, &bh);
- if (shift < 0) {
-@@ -6593,6 +6631,154 @@ ocfs2_find_per_slot_free_list(int type,
- return fl;
- }
-
-+static struct ocfs2_per_slot_free_list *
-+ocfs2_find_preferred_free_list(int type,
-+ int preferred_slot,
-+ int *real_slot,
-+ struct ocfs2_cached_dealloc_ctxt *ctxt)
-+{
-+ struct ocfs2_per_slot_free_list *fl = ctxt->c_first_suballocator;
-+
-+ while (fl) {
-+ if (fl->f_inode_type == type && fl->f_slot == preferred_slot) {
-+ *real_slot = fl->f_slot;
-+ return fl;
-+ }
-+
-+ fl = fl->f_next_suballocator;
-+ }
-+
-+ /* If we can't find any free list matching preferred slot, just use
-+ * the first one.
-+ */
-+ fl = ctxt->c_first_suballocator;
-+ *real_slot = fl->f_slot;
-+
-+ return fl;
-+}
-+
-+/* Return Value 1 indicates empty */
-+static int ocfs2_is_dealloc_empty(struct ocfs2_extent_tree *et)
-+{
-+ struct ocfs2_per_slot_free_list *fl = NULL;
-+
-+ if (!et->et_dealloc)
-+ return 1;
-+
-+ fl = et->et_dealloc->c_first_suballocator;
-+ if (!fl)
-+ return 1;
-+
-+ if (!fl->f_first)
-+ return 1;
-+
-+ return 0;
-+}
-+
-+/* If extent was deleted from tree due to extent rotation and merging, and
-+ * no metadata is reserved ahead of time. Try to reuse some extents
-+ * just deleted. This is only used to reuse extent blocks.
-+ * It is supposed to find enough extent blocks in dealloc if our estimation
-+ * on metadata is accurate.
-+ */
-+static int ocfs2_reuse_blk_from_dealloc(handle_t *handle,
-+ struct ocfs2_extent_tree *et,
-+ struct buffer_head **new_eb_bh,
-+ int blk_wanted, int *blk_given)
-+{
-+ int i, status = 0, real_slot;
-+ struct ocfs2_cached_dealloc_ctxt *dealloc;
-+ struct ocfs2_per_slot_free_list *fl;
-+ struct ocfs2_cached_block_free *bf;
-+ struct ocfs2_extent_block *eb;
-+ struct ocfs2_super *osb =
-+ OCFS2_SB(ocfs2_metadata_cache_get_super(et->et_ci));
-+
-+ *blk_given = 0;
-+
-+ /* If extent tree doesn't have a dealloc, this is not faulty. Just
-+ * tell upper caller dealloc can't provide any block and it should
-+ * ask for alloc to claim more space.
-+ */
-+ dealloc = et->et_dealloc;
-+ if (!dealloc)
-+ goto bail;
-+
-+ for (i = 0; i < blk_wanted; i++) {
-+ /* Prefer to use local slot */
-+ fl = ocfs2_find_preferred_free_list(EXTENT_ALLOC_SYSTEM_INODE,
-+ osb->slot_num, &real_slot,
-+ dealloc);
-+ /* If no more block can be reused, we should claim more
-+ * from alloc. Just return here normally.
-+ */
-+ if (!fl) {
-+ status = 0;
-+ break;
-+ }
-+
-+ bf = fl->f_first;
-+ fl->f_first = bf->free_next;
-+
-+ new_eb_bh[i] = sb_getblk(osb->sb, bf->free_blk);
-+ if (new_eb_bh[i] == NULL) {
-+ status = -ENOMEM;
-+ mlog_errno(status);
-+ goto bail;
-+ }
-+
-+ mlog(0, "Reusing block(%llu) from "
-+ "dealloc(local slot:%d, real slot:%d)\n",
-+ bf->free_blk, osb->slot_num, real_slot);
-+
-+ ocfs2_set_new_buffer_uptodate(et->et_ci, new_eb_bh[i]);
-+
-+ status = ocfs2_journal_access_eb(handle, et->et_ci,
-+ new_eb_bh[i],
-+ OCFS2_JOURNAL_ACCESS_CREATE);
-+ if (status < 0) {
-+ mlog_errno(status);
-+ goto bail;
-+ }
-+
-+ memset(new_eb_bh[i]->b_data, 0, osb->sb->s_blocksize);
-+ eb = (struct ocfs2_extent_block *) new_eb_bh[i]->b_data;
-+
-+ /* We can't guarantee that buffer head is still cached, so
-+ * polutlate the extent block again.
-+ */
-+ strcpy(eb->h_signature, OCFS2_EXTENT_BLOCK_SIGNATURE);
-+ eb->h_blkno = cpu_to_le64(bf->free_blk);
-+ eb->h_fs_generation = cpu_to_le32(osb->fs_generation);
-+ eb->h_suballoc_slot = cpu_to_le16(real_slot);
-+ eb->h_suballoc_loc = cpu_to_le64(bf->free_bg);
-+ eb->h_suballoc_bit = cpu_to_le16(bf->free_bit);
-+ eb->h_list.l_count =
-+ cpu_to_le16(ocfs2_extent_recs_per_eb(osb->sb));
-+
-+ /* We'll also be dirtied by the caller, so
-+ * this isn't absolutely necessary.
-+ */
-+ ocfs2_journal_dirty(handle, new_eb_bh[i]);
-+
-+ if (!fl->f_first) {
-+ dealloc->c_first_suballocator = fl->f_next_suballocator;
-+ kfree(fl);
-+ }
-+ kfree(bf);
-+ }
-+
-+ *blk_given = i;
-+
-+bail:
-+ if (unlikely(status < 0)) {
-+ for (i = 0; i < blk_wanted; i++)
-+ brelse(new_eb_bh[i]);
-+ }
-+
-+ return status;
-+}
-+
- int ocfs2_cache_block_dealloc(struct ocfs2_cached_dealloc_ctxt *ctxt,
- int type, int slot, u64 suballoc,
- u64 blkno, unsigned int bit)
-diff --git a/fs/ocfs2/alloc.h b/fs/ocfs2/alloc.h
-index 4a5152ec88a3..571692171dd1 100644
---- a/fs/ocfs2/alloc.h
-+++ b/fs/ocfs2/alloc.h
-@@ -61,6 +61,7 @@ struct ocfs2_extent_tree {
- ocfs2_journal_access_func et_root_journal_access;
- void *et_object;
- unsigned int et_max_leaf_clusters;
-+ struct ocfs2_cached_dealloc_ctxt *et_dealloc;
- };
-
- /*
-diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
-index 77ec9b495027..2ff02dda97d8 100644
---- a/fs/ocfs2/aops.c
-+++ b/fs/ocfs2/aops.c
-@@ -2322,6 +2322,12 @@ static int ocfs2_dio_end_io_write(struct inode *inode,
-
- ocfs2_init_dinode_extent_tree(&et, INODE_CACHE(inode), di_bh);
-
-+ /* Attach dealloc with extent tree in case that we may reuse extents
-+ * which are already unlinked from current extent tree due to extent
-+ * rotation and merging.
-+ */
-+ et.et_dealloc = &dealloc;
-+
- ret = ocfs2_lock_allocators(inode, &et, 0, dwc->dw_zero_count*2,
- &data_ac, &meta_ac);
- if (ret) {
---
-2.14.2
-
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