On Fri, Nov 22, 2013 at 06:47:59PM +0800, Miao Xie wrote: > 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.
A good candidate for upstream and stable tree. Reviewed-by: Liu Bo <[email protected]> -liubo > > Reported-by: Tsutomu Itoh <[email protected]> > Signed-off-by: Miao Xie <[email protected]> > --- > fs/btrfs/super.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c > index fb62c45..fd05d7a 100644 > --- a/fs/btrfs/super.c > +++ b/fs/btrfs/super.c > @@ -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"); > -- > 1.8.3.1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
