From: Filipe Manana <fdmanana@suse.com>
Date: Tue, 26 Mar 2019 10:49:56 +0000
Git-commit: f35f06c35560a86e841631f0243b83a984dc11a9
Patch-mainline: 5.1
Subject: [PATCH] Btrfs: do not allow trimming when a fs is mounted with
the nologreplay option
References: bsc#1135758
Whan a filesystem is mounted with the nologreplay mount option, which
requires it to be mounted in RO mode as well, we can not allow discard on
free space inside block groups, because log trees refer to extents that
are not pinned in a block group's free space cache (pinning the extents is
precisely the first phase of replaying a log tree).
So do not allow the fitrim ioctl to do anything when the filesystem is
mounted with the nologreplay option, because later it can be mounted RW
without that option, which causes log replay to happen and result in
either a failure to replay the log trees (leading to a mount failure), a
crash or some silent corruption.
Reported-by: Darrick J. Wong <darrick.wong@oracle.com>
Fixes: 96da09192cda ("btrfs: Introduce new mount option to disable tree log replay")
CC: stable@vger.kernel.org # 4.9+
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
---
fs/btrfs/ioctl.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index d0264f604588..5090594a8310 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -387,6 +387,16 @@ static noinline int btrfs_ioctl_fitrim(struct file *file, void __user *arg)
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
+ /*
+ * If the fs is mounted with nologreplay, which requires it to be
+ * mounted in RO mode as well, we can not allow discard on free space
+ * inside block groups, because log trees refer to extents that are not
+ * pinned in a block group's free space cache (pinning the extents is
+ * precisely the first phase of replaying a log tree).
+ */
+ if (btrfs_test_opt(fs_info, NOLOGREPLAY))
+ return -EROFS;
+
rcu_read_lock();
list_for_each_entry_rcu(device, &fs_info->fs_devices->devices,
dev_list) {
--
2.19.0