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| author | Nikolay Borisov <nborisov@suse.com> | 2018-04-18 08:41:54 +0200 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2018-04-20 19:17:25 +0200 |
| commit | 5e388e95815408c27f3612190d089afc0774b870 (patch) | |
| tree | ad9882fb36439900d634df34ea76796957732c3d /fs/btrfs/delayed-ref.h | |
| parent | btrfs: fix unaligned access in readdir (diff) | |
| download | linux-5e388e95815408c27f3612190d089afc0774b870.tar.xz linux-5e388e95815408c27f3612190d089afc0774b870.zip | |
btrfs: Fix race condition between delayed refs and blockgroup removal
When the delayed refs for a head are all run, eventually
cleanup_ref_head is called which (in case of deletion) obtains a
reference for the relevant btrfs_space_info struct by querying the bg
for the range. This is problematic because when the last extent of a
bg is deleted a race window emerges between removal of that bg and the
subsequent invocation of cleanup_ref_head. This can result in cache being null
and either a null pointer dereference or assertion failure.
task: ffff8d04d31ed080 task.stack: ffff9e5dc10cc000
RIP: 0010:assfail.constprop.78+0x18/0x1a [btrfs]
RSP: 0018:ffff9e5dc10cfbe8 EFLAGS: 00010292
RAX: 0000000000000044 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff8d04ffc1f868 RSI: ffff8d04ffc178c8 RDI: ffff8d04ffc178c8
RBP: ffff8d04d29e5ea0 R08: 00000000000001f0 R09: 0000000000000001
R10: ffff9e5dc0507d58 R11: 0000000000000001 R12: ffff8d04d29e5ea0
R13: ffff8d04d29e5f08 R14: ffff8d04efe29b40 R15: ffff8d04efe203e0
FS: 00007fbf58ead500(0000) GS:ffff8d04ffc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe6c6975648 CR3: 0000000013b2a000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
__btrfs_run_delayed_refs+0x10e7/0x12c0 [btrfs]
btrfs_run_delayed_refs+0x68/0x250 [btrfs]
btrfs_should_end_transaction+0x42/0x60 [btrfs]
btrfs_truncate_inode_items+0xaac/0xfc0 [btrfs]
btrfs_evict_inode+0x4c6/0x5c0 [btrfs]
evict+0xc6/0x190
do_unlinkat+0x19c/0x300
do_syscall_64+0x74/0x140
entry_SYSCALL_64_after_hwframe+0x3d/0xa2
RIP: 0033:0x7fbf589c57a7
To fix this, introduce a new flag "is_system" to head_ref structs,
which is populated at insertion time. This allows to decouple the
querying for the spaceinfo from querying the possibly deleted bg.
Fixes: d7eae3403f46 ("Btrfs: rework delayed ref total_bytes_pinned accounting")
CC: stable@vger.kernel.org # 4.14+
Suggested-by: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/delayed-ref.h')
| -rw-r--r-- | fs/btrfs/delayed-ref.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/btrfs/delayed-ref.h b/fs/btrfs/delayed-ref.h index 741869dbc316..7f00db50bd24 100644 --- a/fs/btrfs/delayed-ref.h +++ b/fs/btrfs/delayed-ref.h @@ -127,6 +127,7 @@ struct btrfs_delayed_ref_head { */ unsigned int must_insert_reserved:1; unsigned int is_data:1; + unsigned int is_system:1; unsigned int processing:1; }; |