From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from aserp1040.oracle.com ([141.146.126.69]:24322 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751109Ab3LKJTN (ORCPT ); Wed, 11 Dec 2013 04:19:13 -0500 Date: Wed, 11 Dec 2013 17:19:02 +0800 From: Liu Bo To: Miao Xie Cc: linux-btrfs@vger.kernel.org Subject: Re: [PATCH] Btrfs: don't clear the default compression type Message-ID: <20131211091902.GC22511@localhost.localdomain> Reply-To: bo.li.liu@oracle.com References: <1385117279-32009-1-git-send-email-miaox@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1385117279-32009-1-git-send-email-miaox@cn.fujitsu.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: 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: [] __list_del_entry+0x1/0x98 > [SNIP] > [ 556.512490] [] ? list_del+0xd/0x2b > [ 556.512539] [] find_workspace+0x97/0x175 [btrfs] > [ 556.512546] [] ? _raw_spin_lock+0xe/0x10 > [ 556.512576] [] btrfs_compress_pages+0x2d/0xa2 [btrfs] > [ 556.512601] [] compress_file_range.constprop.54+0x1f2/0x4e8 [btrfs] > [ 556.512627] [] async_cow_start+0x32/0x4d [btrfs] > [ 556.512655] [] worker_loop+0x144/0x4c3 [btrfs] > [ 556.512661] [] ? finish_task_switch+0x80/0xb8 > [ 556.512689] [] ? btrfs_queue_worker+0x244/0x244 [btrfs] > [ 556.512695] [] kthread+0x8d/0x95 > [ 556.512699] [] ? bit_waitqueue+0x34/0x7d > [ 556.512704] [] ? __kthread_parkme+0x65/0x65 > [ 556.512709] [] ret_from_fork+0x7c/0xb0 > [ 556.512713] [] ? __kthread_parkme+0x65/0x65 > > Steps to reproduce: > # mkfs.btrfs -f > # mount -o nodatacow > # touch / > # chattr =c / > # dd if=/dev/zero of=/ 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 -liubo > > Reported-by: Tsutomu Itoh > Signed-off-by: Miao Xie > --- > 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 majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html