Commit 8004198b authored by Aleksa Sarai's avatar Aleksa Sarai Committed by Greg Kroah-Hartman

btrfs: resume qgroup rescan on rw remount

commit 6c6b5a39 upstream.

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: Jeff Mahoney <jeffm@suse.com>
Fixes: b382a324 ("Btrfs: fix qgroup rescan resume on mount")
Signed-off-by: default avatarAleksa Sarai <asarai@suse.de>
Reviewed-by: default avatarNikolay Borisov <nborisov@suse.com>
Tested-by: default avatarNikolay Borisov <nborisov@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 9a5537a7
......@@ -1828,6 +1828,8 @@ 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);
......
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