Patch "xfs: xfs_iflush_cluster fails to abort on error" has been added to the 4.6-stable tree

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

xfs: xfs_iflush_cluster fails to abort on error

to the 4.6-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:
xfs-xfs_iflush_cluster-fails-to-abort-on-error.patch
and it can be found in the queue-4.6 subdirectory.

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

From: Dave Chinner <[email protected]>
Date: Wed, 18 May 2016 13:53:42 +1000
Subject: xfs: xfs_iflush_cluster fails to abort on error

From: Dave Chinner <[email protected]>

commit b1438f477934f5a4d5a44df26f3079a7575d5946 upstream.

When a failure due to an inode buffer occurs, the error handling fails to abort the inode writeback correctly. This can result in the inode being reclaimed whilst still in the AIL, leading to use-after-free situations as well as filesystems that cannot be unmounted as the inode log items left in the AIL never get removed.

Fix this by ensuring fatal errors from xfs_imap_to_bp() result in the inode flush being aborted correctly.

---
 fs/xfs/xfs_inode.c |   17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

@@ -3327,7 +3327,7 @@ xfs_iflush(
 	struct xfs_buf		**bpp)
 {
 	struct xfs_mount	*mp = ip->i_mount;
-	struct xfs_buf		*bp;
+	struct xfs_buf		*bp = NULL;
 	struct xfs_dinode	*dip;
 	int			error;
 

@@ -3369,14 +3369,22 @@ xfs_iflush(
 	}
 
 	/*
-	 * Get the buffer containing the on-disk inode.
+	 * Get the buffer containing the on-disk inode. We are doing a try-lock
+	 * operation here, so we may get  an EAGAIN error. In that case, we
+	 * simply want to return with the inode still dirty.
+	 *
+	 * If we get any other error, we effectively have a corruption situation
+	 * and we cannot flush the inode, so we treat it the same as failing
+	 * xfs_iflush_int().
 	 */
 	error = xfs_imap_to_bp(mp, NULL, &ip->i_imap, &dip, &bp, XBF_TRYLOCK,
 			       0);
-	if (error || !bp) {
+	if (error == -EAGAIN) {
 		xfs_ifunlock(ip);
 		return error;
 	}
+	if (error)
+		goto corrupt_out;
 
 	/*
 	 * First flush out the inode that xfs_iflush was called with.

@@ -3404,7 +3412,8 @@ xfs_iflush(
 	return 0;
 
 corrupt_out:
-	xfs_buf_relse(bp);
+	if (bp)
+		xfs_buf_relse(bp);
 	xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
 cluster_corrupt_out:
 	error = -EFSCORRUPTED;

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

queue-4.6/xfs-xfs_iflush_cluster-fails-to-abort-on-error.patch queue-4.6/xfs-disallow-rw-remount-on-fs-with-unknown-ro-compat-features.patch queue-4.6/xfs-fix-inode-validity-check-in-xfs_iflush_cluster.patch queue-4.6/xfs-skip-stale-inodes-in-xfs_iflush_cluster.patch queue-4.6/xfs-remove-xfs_fs_evict_inode.patch queue-4.6/xfs-don-t-wrap-growfs-agfl-indexes.patch