]> git.proxmox.com Git - mirror_ubuntu-eoan-kernel.git/commit
btrfs: qgroup: Don't copy extent buffer to do qgroup rescan
authorQu Wenruo <quwenruo@cn.fujitsu.com>
Mon, 26 Oct 2015 01:19:43 +0000 (09:19 +0800)
committerChris Mason <clm@fb.com>
Tue, 27 Oct 2015 02:42:30 +0000 (19:42 -0700)
commit0a0e8b89389266bed9cc074c57ea662e4b9b2621
treedc4ba61a3abd9b9c3bf4803127c3a7337450439d
parentb66d62ba1e0d7ada5b89afffe19d12662b5c92c9
btrfs: qgroup: Don't copy extent buffer to do qgroup rescan

Ancient qgroup code call memcpy() on a extent buffer and use it for leaf
iteration.

As extent buffer contains lock, pointers to pages, it's never sane to do
such copy.

The following bug may be caused by this insane operation:
[92098.841309] general protection fault: 0000 [#1] SMP
[92098.841338] Modules linked in: ...
[92098.841814] CPU: 1 PID: 24655 Comm: kworker/u4:12 Not tainted
4.3.0-rc1 #1
[92098.841868] Workqueue: btrfs-qgroup-rescan btrfs_qgroup_rescan_helper
[btrfs]
[92098.842261] Call Trace:
[92098.842277]  [<ffffffffc035a5d8>] ? read_extent_buffer+0xb8/0x110
[btrfs]
[92098.842304]  [<ffffffffc0396d00>] ? btrfs_find_all_roots+0x60/0x70
[btrfs]
[92098.842329]  [<ffffffffc039af3d>]
btrfs_qgroup_rescan_worker+0x28d/0x5a0 [btrfs]

Where btrfs_qgroup_rescan_worker+0x28d is btrfs_disk_key_to_cpu(),
called in reading key from the copied extent_buffer.

This patch will use btrfs_clone_extent_buffer() to a better copy of
extent buffer to deal such case.

Reported-by: Stephane Lesimple <stephane_btrfs@lesimple.fr>
Suggested-by: Filipe Manana <fdmanana@kernel.org>
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
fs/btrfs/qgroup.c