Patch "btrfs: fix a bogus warning when converting only data or metadata" has been added to the 4.9-stable tree

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

btrfs: fix a bogus warning when converting only data or metadata

to the 4.9-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-fix-a-bogus-warning-when-converting-only-data-or-metadata.patch
and it can be found in the queue-4.9 subdirectory.

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

From: Adam Borowski <[email protected]>
Date: Tue, 7 Mar 2017 23:34:44 +0100
Subject: btrfs: fix a bogus warning when converting only data or metadata

From: Adam Borowski <[email protected]>

[ Upstream commit 14506127979a5a3d0c5d9b4cc76ce9d4ec23b717 ]

If your filesystem has, eg, data:raid0 metadata:raid1, and you run "btrfs balance -dconvert=raid1", the meta.target field will be uninitialized. That's otherwise ok, as it's unused except for this warning.

Thus, let's use the existing set of raid levels for the comparison.

As a side effect, non-convert balances will now nag about data>metadata.

---
 fs/btrfs/volumes.c |   12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

@@ -3765,6 +3765,7 @@ int btrfs_balance(struct btrfs_balance_c
 		  struct btrfs_ioctl_balance_args *bargs)
 {
 	struct btrfs_fs_info *fs_info = bctl->fs_info;
+	u64 meta_target, data_target;
 	u64 allowed;
 	int mixed = 0;
 	int ret;

@@ -3861,11 +3862,16 @@ int btrfs_balance(struct btrfs_balance_c
 		}
 	} while (read_seqretry(&fs_info->profiles_lock, seq));
 
-	if (btrfs_get_num_tolerated_disk_barrier_failures(bctl->meta.target) <
-		btrfs_get_num_tolerated_disk_barrier_failures(bctl->data.target)) {
+	/* if we're not converting, the target field is uninitialized */
+	meta_target = (bctl->meta.flags & BTRFS_BALANCE_ARGS_CONVERT) ?
+		bctl->meta.target : fs_info->avail_metadata_alloc_bits;
+	data_target = (bctl->data.flags & BTRFS_BALANCE_ARGS_CONVERT) ?
+		bctl->data.target : fs_info->avail_data_alloc_bits;
+	if (btrfs_get_num_tolerated_disk_barrier_failures(meta_target) <
+		btrfs_get_num_tolerated_disk_barrier_failures(data_target)) {
 		btrfs_warn(fs_info,
 			   "metadata profile 0x%llx has lower redundancy than data profile 0x%llx",
-			   bctl->meta.target, bctl->data.target);
+			   meta_target, data_target);
 	}
 
 	if (bctl->sys.flags & BTRFS_BALANCE_ARGS_CONVERT) {

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

queue-4.9/btrfs-fix-a-bogus-warning-when-converting-only-data-or-metadata.patch