Changwei Ge
2018-Jan-09 06:24 UTC
[Ocfs2-devel] [PATCH RESEND v3 1/2] ocfs2: make metadata estimation accurate and clear
For Andrew's convenience, resend this patch
Current code assume that ::w_unwritten_list always has only one item on.
This is not right and hard to get understood.
So improve how to count unwritten item.
Reported-by: John Lightsey <john at nixnuts.net>
Signed-off-by: Changwei Ge <ge.changwei at h3c.com>
---
fs/ocfs2/aops.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index 88a31e9..77ec9b4 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -784,6 +784,7 @@ struct ocfs2_write_ctxt {
struct ocfs2_cached_dealloc_ctxt w_dealloc;
struct list_head w_unwritten_list;
+ unsigned int w_unwritten_count;
};
void ocfs2_unlock_and_free_pages(struct page **pages, int num_pages)
@@ -1373,6 +1374,7 @@ static int ocfs2_unwritten_check(struct inode *inode,
desc->c_clear_unwritten = 0;
list_add_tail(&new->ue_ip_node, &oi->ip_unwritten_list);
list_add_tail(&new->ue_node, &wc->w_unwritten_list);
+ wc->w_unwritten_count++;
new = NULL;
unlock:
spin_unlock(&oi->ip_lock);
@@ -2246,7 +2248,7 @@ static int ocfs2_dio_get_block(struct inode *inode,
sector_t iblock,
ue->ue_phys = desc->c_phys;
list_splice_tail_init(&wc->w_unwritten_list,
&dwc->dw_zero_list);
- dwc->dw_zero_count++;
+ dwc->dw_zero_count += wc->w_unwritten_count;
}
ret = ocfs2_write_end_nolock(inode->i_mapping, pos, len, len, wc);
--
2.7.4
Changwei Ge
2018-Jan-09 06:24 UTC
[Ocfs2-devel] [PATCH RESEND v3 2/2] ocfs2: try to reuse extent block in dealloc without meta_alloc
For Andrew's convenience, resend this patch A crash issue was reported by John. The call trace 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 althoughenough 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. Change from v2: 1)Separate improvement for how to estimate metadata into respective patch 2)Solve the issue reported by John in last version of this patch - try to reuse metadata in dealloc ahead of claiming new metadata. 3)Add a method ocfs2_find_preferred_free_list() to find space of local slot at higher priority. Reported-by: John Lightsey <john at nixnuts.net> Signed-off-by: Changwei Ge <ge.changwei at h3c.com> --- fs/ocfs2/alloc.c | 208 ++++++++++++++++++++++++++++++++++++++++++++++++++++--- fs/ocfs2/alloc.h | 1 + fs/ocfs2/aops.c | 6 ++ 3 files changed, 205 insertions(+), 10 deletions(-) diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c index addd7c5..ec1ebbf 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) @@ -1158,7 +1166,7 @@ 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; @@ -1213,11 +1221,31 @@ 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 @@ -1340,15 +1368,25 @@ 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; @@ -1511,7 +1549,7 @@ 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) { @@ -6587,6 +6625,156 @@ 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)) { + for (; i >= 0; i--) { + if (new_eb_bh[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 27b75cf..250bcac 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 77ec9b4..2ff02dd 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) { -- 2.7.4