Commits
Qu Wenruo committed 0a0e8b89389
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>