Patch "btrfs: handle errors while updating refcounts in update_ref_for_cow" has been added to the 4.14-stable tree

This is a note to let you know that I've just added the patch titled

btrfs: handle errors while updating refcounts in update_ref_for_cow

to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
btrfs-handle-errors-while-updating-refcounts-in-update_ref_for_cow.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Jeff Mahoney <[email protected]>
Date: Tue, 21 Nov 2017 13:58:49 -0500
Subject: btrfs: handle errors while updating refcounts in update_ref_for_cow

From: Jeff Mahoney <[email protected]>

commit 692826b2738101549f032a761a9191636e83be4e upstream.

Since commit fb235dc06fa (btrfs: qgroup: Move half of the qgroup accounting time out of commit trans) the assumption that btrfs_add_delayed_{data,tree}_ref can only return 0 or -ENOMEM has been false. The qgroup operations call into btrfs_search_slot and friends and can now return the full spectrum of error codes.

Fortunately, the fix here is easy since update_ref_for_cow failing is already handled so we just need to bail early with the error code.

---
 fs/btrfs/ctree.c |   18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

@@ -1032,14 +1032,17 @@ static noinline int update_ref_for_cow(s
 		     root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) &&
 		    !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
 			ret = btrfs_inc_ref(trans, root, buf, 1);
-			BUG_ON(ret); /* -ENOMEM */
+			if (ret)
+				return ret;
 
 			if (root->root_key.objectid ==
 			    BTRFS_TREE_RELOC_OBJECTID) {
 				ret = btrfs_dec_ref(trans, root, buf, 0);
-				BUG_ON(ret); /* -ENOMEM */
+				if (ret)
+					return ret;
 				ret = btrfs_inc_ref(trans, root, cow, 1);
-				BUG_ON(ret); /* -ENOMEM */
+				if (ret)
+					return ret;
 			}
 			new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
 		} else {

@@ -1049,7 +1052,8 @@ static noinline int update_ref_for_cow(s
 				ret = btrfs_inc_ref(trans, root, cow, 1);
 			else
 				ret = btrfs_inc_ref(trans, root, cow, 0);
-			BUG_ON(ret); /* -ENOMEM */
+			if (ret)
+				return ret;
 		}
 		if (new_flags != 0) {
 			int level = btrfs_header_level(buf);

@@ -1068,9 +1072,11 @@ static noinline int update_ref_for_cow(s
 				ret = btrfs_inc_ref(trans, root, cow, 1);
 			else
 				ret = btrfs_inc_ref(trans, root, cow, 0);
-			BUG_ON(ret); /* -ENOMEM */
+			if (ret)
+				return ret;
 			ret = btrfs_dec_ref(trans, root, buf, 1);
-			BUG_ON(ret); /* -ENOMEM */
+			if (ret)
+				return ret;
 		}
 		clean_tree_block(fs_info, buf);
 		*last_ref = 1;

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/btrfs-fix-missing-error-return-in-btrfs_drop_snapshot.patch queue-4.14/btrfs-handle-errors-while-updating-refcounts-in-update_ref_for_cow.patch