Btrfs: kernel operation should come after user input has been verified

By general rule of thumb there shouldn't be any way that user land
could trigger a kernel operation just by sending wrong arguments.

Here do commit cleanups after user input has been verified.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 13 insertions, 13 deletions

diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index 7aed8a8ce694..02031fc07f7f 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -327,19 +327,6 @@ int btrfs_dev_replace_start(struct btrfs_root *root,
             args->start.tgtdev_name[0] == '\0')
                 return -EINVAL;
 
-        /*
-         * Here we commit the transaction to make sure commit_total_bytes
-         * of all the devices are updated.
-         */
-        trans = btrfs_attach_transaction(root);
-        if (!IS_ERR(trans)) {
-                ret = btrfs_commit_transaction(trans, root);
-                if (ret)
-                        return ret;
-        } else if (PTR_ERR(trans) != -ENOENT) {
-                return PTR_ERR(trans);
-        }
-
         /* the disk copy procedure reuses the scrub code */
         mutex_lock(&fs_info->volume_mutex);
         ret = btrfs_dev_replace_find_srcdev(root, args->start.srcdevid,
@@ -356,6 +343,19 @@ int btrfs_dev_replace_start(struct btrfs_root *root,
         if (ret)
                 return ret;
 
+        /*
+         * Here we commit the transaction to make sure commit_total_bytes
+         * of all the devices are updated.
+         */
+        trans = btrfs_attach_transaction(root);
+        if (!IS_ERR(trans)) {
+                ret = btrfs_commit_transaction(trans, root);
+                if (ret)
+                        return ret;
+        } else if (PTR_ERR(trans) != -ENOENT) {
+                return PTR_ERR(trans);
+        }
+
         btrfs_dev_replace_lock(dev_replace);
         switch (dev_replace->replace_state) {
         case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED: