diff options
author | Qu Wenruo <wqu@suse.com> | 2017-11-22 17:03:15 +0800 |
---|---|---|
committer | David Sterba <dsterba@suse.com> | 2018-01-03 17:09:07 +0100 |
commit | beb06b63cc9a54f0d33dae43c3c6ff956ccc885a (patch) | |
tree | e557180c59560f0ff67478989258534cce498d4d | |
parent | 86fe5fb2c15aa49e4b98ad83c071d5d63895a0be (diff) |
btrfs-progs: lowmem check: Fix regression which screws up extent allocator
[BUG]
Commit 723427d7e6b7 ("btrfs-progs: check: change the way lowmem mode
traverses metadata") introduces a regression which could make some fsck
self test case to fail.
For fsck test case 004-no-dir-item, btrfs check --mode=lowmem --repair
can cause BUG_ON() with ret = -17 (-EEXIST) when committing transaction.
The problem happens with the following backtrace:
./btrfs(+0x22045)[0x555d0dade045]
./btrfs(+0x2216f)[0x555d0dade16f]
./btrfs(+0x29df1)[0x555d0dae5df1]
./btrfs(+0x2a142)[0x555d0dae6142]
./btrfs(btrfs_alloc_free_block+0x78)[0x555d0dae6202]
./btrfs(__btrfs_cow_block+0x177)[0x555d0dad00a2]
./btrfs(btrfs_cow_block+0x116)[0x555d0dad05a8]
./btrfs(commit_tree_roots+0x91)[0x555d0db1fd4f]
./btrfs(btrfs_commit_transaction+0x18c)[0x555d0db20100]
./btrfs(btrfs_fix_super_size+0x190)[0x555d0db005a4]
./btrfs(btrfs_fix_device_and_super_size+0x177)[0x555d0db00771]
./btrfs(cmd_check+0x1757)[0x555d0db4f6ab]
./btrfs(main+0x138)[0x555d0dace5dd]
/usr/lib/libc.so.6(__libc_start_main+0xea)[0x7fa5e4613f6a]
./btrfs(_start+0x2a)[0x555d0dacddda]
The bug is triggered by that, extent allocator considers range
[29360128, 29376512) as free and allocates it. However when inserting
EXTENT_ITEM, btrfs finds there is already one tree block (fs tree root),
returning -EEXIST and causing the later BUG_ON().
[CAUSE]
The cause is in repair mode, lowmem check always pins all metadata
blocks. However pinned metadata blocks will be unpined when transaction
commits, and will be marked as *FREE* space.
So later extent allocator will consider such range free and allocates
them incorrectly.
[FIX]
Don't pin metadata blocks without valid reason or preparation (like
discard all free space cache to re-calculate free space on next write).
Fixes: 723427d7e6b7 ("btrfs-progs: check: change the way lowmem mode traverses metadata")
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
-rw-r--r-- | cmds-check.c | 10 |
1 files changed, 0 insertions, 10 deletions
diff --git a/cmds-check.c b/cmds-check.c index a93ac2c8..644ee084 100644 --- a/cmds-check.c +++ b/cmds-check.c @@ -6623,8 +6623,6 @@ out: return ret; } -static int pin_metadata_blocks(struct btrfs_fs_info *fs_info); - /* * Iterate all items in the tree and call check_inode_item() to check. * @@ -13306,8 +13304,6 @@ out: return err; } -static int pin_metadata_blocks(struct btrfs_fs_info *fs_info); - /* * Low memory usage version check_chunks_and_extents. */ @@ -13326,12 +13322,6 @@ static int check_chunks_and_extents_v2(struct btrfs_fs_info *fs_info) root = fs_info->fs_root; if (repair) { - /* pin every tree block to avoid extent overwrite */ - ret = pin_metadata_blocks(fs_info); - if (ret) { - error("failed to pin metadata blocks"); - return ret; - } trans = btrfs_start_transaction(fs_info->extent_root, 1); if (IS_ERR(trans)) { error("failed to start transaction before check"); |