4.18-stable review patch. If anyone has any objections, please let me know.
------------------
From: David Sterba <dsterba@xxxxxxxx>
[ Upstream commit 5139cff598d42b1e531f40c84691a7e945f04553 ]
Prepartory work to fix race between mount and device scan.
btrfs_parse_early_options calls the device scan from mount and we'll
need to let mount completely manage the critical section.
Reviewed-by: Anand Jain <anand.jain@xxxxxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/btrfs/super.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -892,6 +892,8 @@ static int btrfs_parse_early_options(con
char *device_name, *opts, *orig, *p;
int error = 0;
+ lockdep_assert_held(&uuid_mutex);
+
if (!options)
return 0;
@@ -917,10 +919,8 @@ static int btrfs_parse_early_options(con
error = -ENOMEM;
goto out;
}
- mutex_lock(&uuid_mutex);
error = btrfs_scan_one_device(device_name,
flags, holder, fs_devices);
- mutex_unlock(&uuid_mutex);
kfree(device_name);
if (error)
goto out;
@@ -1528,8 +1528,10 @@ static struct dentry *btrfs_mount_root(s
if (!(flags & SB_RDONLY))
mode |= FMODE_WRITE;
+ mutex_lock(&uuid_mutex);
error = btrfs_parse_early_options(data, mode, fs_type,
&fs_devices);
+ mutex_unlock(&uuid_mutex);
if (error) {
return ERR_PTR(error);
}
