btrfs: fix null pointer deference at btrfs_sysfs_add_one+0x105
authorAnand Jain <Anand.Jain@oracle.com>
Wed, 15 Jan 2014 09:22:28 +0000 (17:22 +0800)
committerChris Mason <clm@fb.com>
Sat, 15 Feb 2014 16:03:09 +0000 (08:03 -0800)
commitf085381e6d08f4c8d6882825f31accd455c54d70
treea2288e14def975689e3f32c9960c9a0f68aa6d19
parent3a0dfa6a12e4bb64a434426ecb17d4842092db5e
btrfs: fix null pointer deference at btrfs_sysfs_add_one+0x105

bdev is null when disk has disappeared and mounted with
the degrade option

stack trace
---------
btrfs_sysfs_add_one+0x105/0x1c0 [btrfs]
open_ctree+0x15f3/0x1fe0 [btrfs]
btrfs_mount+0x5db/0x790 [btrfs]
? alloc_pages_current+0xa4/0x160
mount_fs+0x34/0x1b0
vfs_kern_mount+0x62/0xf0
do_mount+0x22e/0xa80
? __get_free_pages+0x9/0x40
? copy_mount_options+0x31/0x170
SyS_mount+0x7e/0xc0
system_call_fastpath+0x16/0x1b
---------

reproducer:
-------
mkfs.btrfs -draid1 -mraid1 /dev/sdc /dev/sdd
(detach a disk)
devmgt detach /dev/sdc [1]
mount -o degrade /dev/sdd /btrfs
-------

[1] github.com/anajain/devmgt.git

Signed-off-by: Anand Jain <Anand.Jain@oracle.com>
Tested-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
fs/btrfs/sysfs.c