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Btrfs: don't clear the default compression type

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We met a oops caused by the wrong compression type:
[  556.512356] BUG: unable to handle kernel NULL pointer dereference at           (null)
[  556.512370] IP: [<ffffffff811dbaa0>] __list_del_entry+0x1/0x98
[SNIP]
[  556.512490]  [<ffffffff811dbb44>] ? list_del+0xd/0x2b
[  556.512539]  [<ffffffffa05dd5ce>] find_workspace+0x97/0x175 [btrfs]
[  556.512546]  [<ffffffff813c14b5>] ? _raw_spin_lock+0xe/0x10
[  556.512576]  [<ffffffffa05de276>] btrfs_compress_pages+0x2d/0xa2 [btrfs]
[  556.512601]  [<ffffffffa05af060>] compress_file_range.constprop.54+0x1f2/0x4e8 [btrfs]
[  556.512627]  [<ffffffffa05af388>] async_cow_start+0x32/0x4d [btrfs]
[  556.512655]  [<ffffffffa05cc7a1>] worker_loop+0x144/0x4c3 [btrfs]
[  556.512661]  [<ffffffff81059404>] ? finish_task_switch+0x80/0xb8
[  556.512689]  [<ffffffffa05cc65d>] ? btrfs_queue_worker+0x244/0x244 [btrfs]
[  556.512695]  [<ffffffff8104fa4e>] kthread+0x8d/0x95
[  556.512699]  [<ffffffff81050000>] ? bit_waitqueue+0x34/0x7d
[  556.512704]  [<ffffffff8104f9c1>] ? __kthread_parkme+0x65/0x65
[  556.512709]  [<ffffffff813c7eec>] ret_from_fork+0x7c/0xb0
[  556.512713]  [<ffffffff8104f9c1>] ? __kthread_parkme+0x65/0x65

Steps to reproduce:
 # mkfs.btrfs -f <dev>
 # mount -o nodatacow <dev> <mnt>
 # touch <mnt>/<file>
 # chattr =c <mnt>/<file>
 # dd if=/dev/zero of=<mnt>/<file> bs=1M count=10

It is because we cleared the default compression type when setting the
nodatacow. In fact, we needn't do it because we have used COMPRESS flag to
indicate if we need compressed the file data or not, needn't use the
variant -- compress_type -- in btrfs_info to do the same thing, and just
use it to hold the default compression type. Or we would get a wrong compress
type for a file whose own compress flag is set but the compress flag of its
filesystem is not set.

Reported-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
Miao Xie 2013-11-22 18:47:59 +08:00 committed by Chris Mason
parent c0778e2534
commit a7e252af5a
1 changed files with 2 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
fs/btrfs/super.c
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@ -432,7 +432,6 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
} else {
printk(KERN_INFO "btrfs: setting nodatacow\n");
}
info->compress_type = BTRFS_COMPRESS_NONE;
btrfs_clear_opt(info->mount_opt, COMPRESS);
btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
btrfs_set_opt(info->mount_opt, NODATACOW);
@ -461,7 +460,6 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
btrfs_set_fs_incompat(info, COMPRESS_LZO);
} else if (strncmp(args[0].from, "no", 2) == 0) {
compress_type = "no";
info->compress_type = BTRFS_COMPRESS_NONE;
btrfs_clear_opt(info->mount_opt, COMPRESS);
btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
compress_force = false;
@ -474,9 +472,10 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
btrfs_set_opt(info->mount_opt, FORCE_COMPRESS);
pr_info("btrfs: force %s compression\n",
compress_type);
} else
} else if (btrfs_test_opt(root, COMPRESS)) {
pr_info("btrfs: use %s compression\n",
compress_type);
}
break;
case Opt_ssd:
printk(KERN_INFO "btrfs: use ssd allocation scheme\n");