Revert "Btrfs: race free update of commit root for ro snapshots"

[karo-tx-linux.git] / fs / btrfs / ioctl.c

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index e732274f1afd9c0e7ed8075465c00d1a40a6cfcf..33c80f560f98d17a4de320c910f3f9ec7be25478 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -713,6 +713,39 @@ static int create_snapshot(struct btrfs_root *root, struct inode *dir,
        if (ret)
                goto fail;
 
+       ret = btrfs_orphan_cleanup(pending_snapshot->snap);
+       if (ret)
+               goto fail;
+
+       /*
+        * If orphan cleanup did remove any orphans, it means the tree was
+        * modified and therefore the commit root is not the same as the
+        * current root anymore. This is a problem, because send uses the
+        * commit root and therefore can see inode items that don't exist
+        * in the current root anymore, and for example make calls to
+        * btrfs_iget, which will do tree lookups based on the current root
+        * and not on the commit root. Those lookups will fail, returning a
+        * -ESTALE error, and making send fail with that error. So make sure
+        * a send does not see any orphans we have just removed, and that it
+        * will see the same inodes regardless of whether a transaction
+        * commit happened before it started (meaning that the commit root
+        * will be the same as the current root) or not.
+        */
+       if (readonly && pending_snapshot->snap->node !=
+           pending_snapshot->snap->commit_root) {
+               trans = btrfs_join_transaction(pending_snapshot->snap);
+               if (IS_ERR(trans) && PTR_ERR(trans) != -ENOENT) {
+                       ret = PTR_ERR(trans);
+                       goto fail;
+               }
+               if (!IS_ERR(trans)) {
+                       ret = btrfs_commit_transaction(trans,
+                                                      pending_snapshot->snap);
+                       if (ret)
+                               goto fail;
+               }
+       }
+
        inode = btrfs_lookup_dentry(dentry->d_parent->d_inode, dentry);
        if (IS_ERR(inode)) {
                ret = PTR_ERR(inode);