From 6c6b5a39c4bf3dbd8cf629c9f5450e983c19dbb9 Mon Sep 17 00:00:00 2001 From: Aleksa Sarai Date: Tue, 4 Jul 2017 21:49:06 +1000 Subject: [PATCH] btrfs: resume qgroup rescan on rw remount Several distributions mount the "proper root" as ro during initrd and then remount it as rw before pivot_root(2). Thus, if a rescan had been aborted by a previous shutdown, the rescan would never be resumed. This issue would manifest itself as several btrfs ioctl(2)s causing the entire machine to hang when btrfs_qgroup_wait_for_completion was hit (due to the fs_info->qgroup_rescan_running flag being set but the rescan itself not being resumed). Notably, Docker's btrfs storage driver makes regular use of BTRFS_QUOTA_CTL_DISABLE and BTRFS_IOC_QUOTA_RESCAN_WAIT (causing this problem to be manifested on boot for some machines). Cc: # v3.11+ Cc: Jeff Mahoney Fixes: b382a324b60f ("Btrfs: fix qgroup rescan resume on mount") Signed-off-by: Aleksa Sarai Reviewed-by: Nikolay Borisov Tested-by: Nikolay Borisov Signed-off-by: David Sterba --- fs/btrfs/super.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 58650f2..2351794 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -1815,6 +1815,8 @@ static int btrfs_remount(struct super_block *sb, int *flags, char *data) goto restore; } + btrfs_qgroup_rescan_resume(fs_info); + if (!fs_info->uuid_root) { btrfs_info(fs_info, "creating UUID tree"); ret = btrfs_create_uuid_tree(fs_info); -- 2.7.4