Patch "btrfs: do not write corrupted metadata blocks to disk" has been added to the 4.5-stable tree

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

btrfs: do not write corrupted metadata blocks to disk

to the 4.5-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-do-not-write-corrupted-metadata-blocks-to-disk.patch
and it can be found in the queue-4.5 subdirectory.

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

From: Alex Lyakas <[email protected]>
Date: Thu, 10 Mar 2016 13:10:15 +0200
Subject: btrfs: do not write corrupted metadata blocks to disk

From: Alex Lyakas <[email protected]>

commit 0f805531daa2ebfb5706422dc2ead1cff9e53e65 upstream.

csum_dirty_buffer was issuing a warning in case the extent buffer did not look alright, but was still returning success.
Let's return error in this case, and also add an additional sanity check on the extent buffer header.
The caller up the chain may BUG_ON on this, for example flush_epd_write_bio will, but it is better than to have a silent metadata corruption on disk.

---
 fs/btrfs/disk-io.c |   15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

@@ -513,9 +513,20 @@ static int csum_dirty_buffer(struct btrf
 	eb = (struct extent_buffer *)page->private;
 	if (page != eb->pages[0])
 		return 0;
+
 	found_start = btrfs_header_bytenr(eb);
-	if (WARN_ON(found_start != start || !PageUptodate(page)))
-		return 0;
+	/*
+	 * Please do not consolidate these warnings into a single if.
+	 * It is useful to know what went wrong.
+	 */
+	if (WARN_ON(found_start != start))
+		return -EUCLEAN;
+	if (WARN_ON(!PageUptodate(page)))
+		return -EUCLEAN;
+
+	ASSERT(memcmp_extent_buffer(eb, fs_info->fsid,
+			btrfs_header_fsid(), BTRFS_FSID_SIZE) == 0);
+
 	return csum_tree_block(fs_info, eb, 0);
 }
 

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

queue-4.5/btrfs-csum_tree_block-return-proper-errno-value.patch queue-4.5/btrfs-do-not-write-corrupted-metadata-blocks-to-disk.patch