btrfs: lift uuid_mutex to callers of btrfs_parse_early_options

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@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index d470eb6..de87b7b 100644 (file)
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -890,6 +890,8 @@ static int btrfs_parse_early_options(const char *options, fmode_t flags,
        char *device_name, *opts, *orig, *p;
        int error = 0;
 
+       lockdep_assert_held(&uuid_mutex);
+
        if (!options)
                return 0;
 
@@ -915,10 +917,8 @@ static int btrfs_parse_early_options(const char *options, fmode_t flags,
                                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;
@@ -1526,8 +1526,10 @@ static struct dentry *btrfs_mount_root(struct file_system_type *fs_type,
        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);
        }