linux-kernel - [PATCH 3.16 137/410] NFS: commit direct writes even if they fail partially

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Message-ID: <lsq.1528380321.525524252@decadent.org.uk>
Date:   Thu, 07 Jun 2018 15:05:21 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "J. Bruce Fields" <bfields@...hat.com>,
        "Trond Myklebust" <trond.myklebust@...marydata.com>
Subject: [PATCH 3.16 137/410] NFS: commit direct writes even if they fail
 partially

3.16.57-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: "J. Bruce Fields" <bfields@...hat.com>

commit 1b8d97b0a837beaf48a8449955b52c650a7114b4 upstream.

If some of the WRITE calls making up an O_DIRECT write syscall fail,
we neglect to commit, even if some of the WRITEs succeed.

We also depend on the commit code to free the reference count on the
nfs_page taken in the "if (request_commit)" case at the end of
nfs_direct_write_completion().  The problem was originally noticed
because ENOSPC's encountered partway through a write would result in a
closed file being sillyrenamed when it should have been unlinked.

Signed-off-by: J. Bruce Fields <bfields@...hat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@...marydata.com>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 fs/nfs/direct.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -732,10 +732,8 @@ static void nfs_direct_write_completion(

 	spin_lock(&dreq->lock);

-	if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
-		dreq->flags = 0;
+	if (test_bit(NFS_IOHDR_ERROR, &hdr->flags))
 		dreq->error = hdr->error;
-	}
 	if (dreq->error != 0)
 		bit = NFS_IOHDR_ERROR;
 	else {