From 3eb52487d917d81e7f7ff3e46fafad221e1d3637 Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Tue, 26 Mar 2019 10:49:56 +0000 Subject: Btrfs: do not allow trimming when a fs is mounted with the nologreplay option commit f35f06c35560a86e841631f0243b83a984dc11a9 upstream. 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 Fixes: 96da09192cda ("btrfs: Introduce new mount option to disable tree log replay") CC: stable@vger.kernel.org # 4.9+ Reviewed-by: Nikolay Borisov Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/ioctl.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index cddd63b9103f..dd3b4820ac30 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -357,6 +357,16 @@ 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) { -- cgit v1.2.3