Patch "xfs: don't unconditionally clear the reflink flag on zero-block files" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

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

    xfs: don't unconditionally clear the reflink flag on zero-block files

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:
     xfs-don-t-unconditionally-clear-the-reflink-flag-on-zero-block-files.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 <stable@vger.kernel.org> know about it.


>From cc6f77710a6de6210f9feda7cd53e2f5ee7a7e69 Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <darrick.wong@oracle.com>
Date: Mon, 18 Sep 2017 09:41:16 -0700
Subject: xfs: don't unconditionally clear the reflink flag on zero-block files

From: Darrick J. Wong <darrick.wong@oracle.com>

commit cc6f77710a6de6210f9feda7cd53e2f5ee7a7e69 upstream.

If we have speculative cow preallocations hanging around in the cow
fork, don't let a truncate operation clear the reflink flag because if
we do then there's a chance we'll forget to free those extents when we
destroy the incore inode.

Reported-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/xfs/xfs_inode.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -1632,10 +1632,12 @@ xfs_itruncate_extents(
 		goto out;
 
 	/*
-	 * Clear the reflink flag if we truncated everything.
+	 * Clear the reflink flag if there are no data fork blocks and
+	 * there are no extents staged in the cow fork.
 	 */
-	if (ip->i_d.di_nblocks == 0 && xfs_is_reflink_inode(ip)) {
-		ip->i_d.di_flags2 &= ~XFS_DIFLAG2_REFLINK;
+	if (xfs_is_reflink_inode(ip) && ip->i_cnextents == 0) {
+		if (ip->i_d.di_nblocks == 0)
+			ip->i_d.di_flags2 &= ~XFS_DIFLAG2_REFLINK;
 		xfs_inode_clear_cowblocks_tag(ip);
 	}
 


Patches currently in stable-queue which might be from darrick.wong@oracle.com are

queue-4.9/xfs-don-t-unconditionally-clear-the-reflink-flag-on-zero-block-files.patch
queue-4.9/xfs-cancel-dirty-pages-on-invalidation.patch
queue-4.9/xfs-reinit-btree-pointer-on-attr-tree-inactivation-walk.patch
queue-4.9/xfs-report-zeroed-or-not-correctly-in-xfs_zero_range.patch
queue-4.9/xfs-move-more-rt-specific-code-under-config_xfs_rt.patch
queue-4.9/xfs-don-t-change-inode-mode-if-acl-update-fails.patch
queue-4.9/xfs-handle-error-if-xfs_btree_get_bufs-fails.patch
queue-4.9/xfs-update-i_size-after-unwritten-conversion-in-dio-completion.patch
queue-4.9/xfs-trim-writepage-mapping-to-within-eof.patch
queue-4.9/xfs-handle-racy-aio-in-xfs_reflink_end_cow.patch
queue-4.9/xfs-evict-cow-fork-extents-when-performing-finsert-fcollapse.patch
queue-4.9/xfs-capture-state-of-the-right-inode-in-xfs_iflush_done.patch
queue-4.9/fs-xfs-use-ps-printk-format-for-direct-addresses.patch
queue-4.9/xfs-perag-initialization-should-only-touch-m_ag_max_usable-for-ag-0.patch
queue-4.9/xfs-always-swap-the-cow-forks-when-swapping-extents.patch
queue-4.9/xfs-don-t-log-uninitialised-fields-in-inode-structures.patch