From: Zhao Lei <zhao...@cn.fujitsu.com>
Scrub panic in following operation:
mkfs.ext4 /dev/vdh
btrfs-convert /dev/vdh
mount /dev/vdh /mnt/tmp1
btrfs scrub start -B /dev/vdh
(panic)
Reason:
1: In some case, leaf created by btrfs-convert was splited into 2
strips.
2: Scrub bypassed part of above wrong leaf data, but remain data
caused panic in scrub_checksum_tree_block().
For reason 1:
we can get following information after some simple operation.
a. mkfs.ext4 /dev/vdh
btrfs-convert /dev/vdh
b. btrfs-debug-tree /dev/vdh
we can see following item in extent tree:
item 25 key (27054080 METADATA_ITEM 0) itemoff 15083 itemsize 33
Its logical address is [27054080, 27070464)
and acrossed 2 strips:
[27000832, 27066368)
[27066368, 27131904)
Will be fixed in btrfs-progs(btrfs-convert, btrfsck, ...)
For reason 2:
Scrub is trying to do a "bypass" in this case, but the result is
"panic", because current code lacks of some condition in bypass,
and let some wrong leaf data escaped.
This patch fixed above scrub code.
Before patch:
# btrfs scrub start -B /dev/vdh
(panic)
After patch:
# btrfs scrub start -B /dev/vdh
scrub done for 353cec8f-da31-4a94-aa35-be72d997b06e
...
# dmesg
...
[ 59.088697] BTRFS error (device vdh): scrub: tree block 27054080 spanning
stripes, ignored. logical=27000832
[ 59.089929] BTRFS error (device vdh): scrub: tree block 27054080 spanning
stripes, ignored. logical=27066368
#
Reported-by: Chris Murphy <li...@colorremedies.com>
Signed-off-by: Zhao Lei <zhao...@cn.fujitsu.com>
---
fs/btrfs/scrub.c | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 94db0fa..35d49b2 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -2881,11 +2881,12 @@ static noinline_for_stack int
scrub_raid56_parity(struct scrub_ctx *sctx,
flags = btrfs_extent_flags(l, extent);
generation = btrfs_extent_generation(l, extent);
- if (key.objectid < logic_start &&
- (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)) {
- btrfs_err(fs_info,
- "scrub: tree block %llu spanning
stripes, ignored. logical=%llu",
- key.objectid, logic_start);
+ if ((flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) &&
+ (key.objectid < logic_start ||
+ key.objectid + bytes >
+ logic_start + map->stripe_len)) {
+ btrfs_err(fs_info, "scrub: tree block %llu
spanning stripes, ignored. logical=%llu",
+ key.objectid, logic_start);
goto next;
}
again:
@@ -3212,8 +3213,10 @@ static noinline_for_stack int scrub_stripe(struct
scrub_ctx *sctx,
flags = btrfs_extent_flags(l, extent);
generation = btrfs_extent_generation(l, extent);
- if (key.objectid < logical &&
- (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)) {
+ if ((flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) &&
+ (key.objectid < logical ||
+ key.objectid + bytes >
+ logical + map->stripe_len)) {
btrfs_err(fs_info,
"scrub: tree block %llu spanning "
"stripes, ignored. logical=%llu",
--
1.8.5.1
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