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btrfs-progs: Fix wrong tree block alignment for unalianged block group

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Commit 854437ca(btrfs-progs: extent-tree: avoid allocating tree block
that crosses stripe boundary) introduces check for logical bytenr not
crossing stripe boundary.

However that check is not completely correct.
It only checks if the logical bytenr and length agaist absolute logical
offset.
That's to say, it only check if a tree block lies in 64K logical stripe.

But in fact, it's possible a block group starts at bytenr unaligned with
64K, just like the following case.

Then btrfsck will give false alert.

0       32K       64K       96K        128K         160K ...
        |--------------- Block group A ---------------------
	|<-----TB 32K------>|
        |/Scrub stripe unit/|
|    WRONG UNIT   |

In that case, TB(tree block) at bytenr 32K in fact fits into the kernel
scrub stripe unit.
But doesn't fit into the pure logical 64K stripe.

Fix check_crossing_stripes() to compare bytenr to block group start, not
to absolute logical bytenr.

Reported-by: Jussi Kansanen <jussi.kansanen@gmail.com>
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2016-10-24 15:22:33 +08:00 committed by David Sterba
parent b2fbfc8cdd
commit ffb1b847bd
3 changed files with 38 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
cmds-check.c
View File

@ -4662,8 +4662,8 @@ static int add_extent_rec_nolookup(struct cache_tree *extent_cache,
bytes_used += rec->nr;
if (tmpl->metadata)
rec->crossing_stripes = check_crossing_stripes(rec->start,
global_info->tree_root->nodesize);
rec->crossing_stripes = check_crossing_stripes(global_info,
rec->start, global_info->tree_root->nodesize);
check_extent_type(rec);
return ret;
}
@ -4764,7 +4764,8 @@ static int add_extent_rec(struct cache_tree *extent_cache,
*/
if (tmpl->metadata)
rec->crossing_stripes = check_crossing_stripes(
rec->start, global_info->tree_root->nodesize);
global_info, rec->start,
global_info->tree_root->nodesize);
check_extent_type(rec);
maybe_free_extent_rec(extent_cache, rec);
return ret;
@ -9359,7 +9360,8 @@ static int check_extent_item(struct btrfs_fs_info *fs_info,
if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
metadata = 1;
if (metadata && check_crossing_stripes(key.objectid, eb->len)) {
if (metadata && check_crossing_stripes(global_info, key.objectid,
eb->len)) {
error("bad metadata [%llu, %llu) crossing stripe boundary",
key.objectid, key.objectid + nodesize);
err |= CROSSING_STRIPE_BOUNDARY;

15
extent-tree.c
View File

@ -2606,11 +2606,20 @@ check_failed:
}
if (!(data & BTRFS_BLOCK_GROUP_DATA)) {
if (check_crossing_stripes(ins->objectid, num_bytes)) {
search_start = round_down(ins->objectid + num_bytes,
BTRFS_STRIPE_LEN);
if (check_crossing_stripes(info, ins->objectid, num_bytes)) {
struct btrfs_block_group_cache *bg_cache;
u64 bg_offset;
bg_cache = btrfs_lookup_block_group(info, ins->objectid);
if (!bg_cache)
goto no_bg_cache;
bg_offset = ins->objectid - bg_cache->key.objectid;
search_start = round_up(bg_offset + num_bytes,
BTRFS_STRIPE_LEN) + bg_offset;
goto new_group;
}
no_bg_cache:
block_group = btrfs_lookup_block_group(info, ins->objectid);
if (block_group)
trans->block_group = block_group;

23
volumes.h
View File

@ -155,11 +155,28 @@ struct map_lookup {
* Check if the given range cross stripes.
* To ensure kernel scrub won't causing bug on with METADATA in mixed
* block group
*
* Return 1 if the range crosses STRIPE boundary
* Return 0 if the range doesn't cross STRIPE boundary or it
* doesn't belong to any block group (no boundary to cross)
*/
static inline int check_crossing_stripes(u64 start, u64 len)
static inline int check_crossing_stripes(struct btrfs_fs_info *fs_info,
u64 start, u64 len)
{
return (start / BTRFS_STRIPE_LEN) !=
((start + len - 1) / BTRFS_STRIPE_LEN);
struct btrfs_block_group_cache *bg_cache;
u64 bg_offset;
bg_cache = btrfs_lookup_block_group(fs_info, start);
/*
* Does not belong to block group, no boundary to cross
* although it's a bigger problem, but here we don't care.
*/
if (!bg_cache)
return 0;
bg_offset = start - bg_cache->key.objectid;
return (bg_offset / BTRFS_STRIPE_LEN !=
(bg_offset + len - 1) / BTRFS_STRIPE_LEN);
}
int __btrfs_map_block(struct btrfs_mapping_tree *map_tree, int rw,