Patch "btrfs: propagate error to btrfs_cmp_data_prepare caller" 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: propagate error to btrfs_cmp_data_prepare caller

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-propagate-error-to-btrfs_cmp_data_prepare-caller.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: Naohiro Aota <[email protected]>
Date: Fri, 8 Sep 2017 17:48:55 +0900
Subject: btrfs: propagate error to btrfs_cmp_data_prepare caller

From: Naohiro Aota <[email protected]>

commit 78ad4ce014d025f41b8dde3a81876832ead643cf upstream.

btrfs_cmp_data_prepare() (almost) always returns 0 i.e. ignoring errors from gather_extent_pages(). While the pages are freed by btrfs_cmp_data_free(), cmp->num_pages still has > 0. Then, btrfs_extent_same() try to access the already freed pages causing faults (or violates PageLocked assertion).

This patch just return the error as is so that the caller stop the process.

---
 fs/btrfs/ioctl.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -3052,7 +3052,7 @@ static int btrfs_cmp_data_prepare(struct
 out:
 	if (ret)
 		btrfs_cmp_data_free(cmp);
-	return 0;
+	return ret;
 }
 
 static int btrfs_cmp_data(struct inode *src, u64 loff, struct inode *dst,

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

queue-4.9/btrfs-propagate-error-to-btrfs_cmp_data_prepare-caller.patch queue-4.9/btrfs-fix-null-pointer-dereference-from-free_reloc_roots.patch