linux-kernel - [PATCH 4.2 082/134] NFS: nfs_set_pgio

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Message-Id: <20150926205316.766649859@linuxfoundation.org>
Date:	Sat, 26 Sep 2015 13:55:34 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org,
	Trond Myklebust <trond.myklebust@...marydata.com>
Subject: [PATCH 4.2 082/134] NFS: nfs_set_pgio_error sometimes misses errors

4.2-stable review patch.  If anyone has any objections, please let me know.

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

From: Trond Myklebust <trond.myklebust@...marydata.com>

commit e9ae58aeee8842a50f7e199d602a5ccb2e41a95f upstream.

We should ensure that we always set the pgio_header's error field
if a READ or WRITE RPC call returns an error. The current code depends
on 'hdr->good_bytes' always being initialised to a large value, which
is not always done correctly by callers.
When this happens, applications may end up missing important errors.

Signed-off-by: Trond Myklebust <trond.myklebust@...marydata.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/nfs/pagelist.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -77,8 +77,8 @@ EXPORT_SYMBOL_GPL(nfs_pgheader_init);
 void nfs_set_pgio_error(struct nfs_pgio_header *hdr, int error, loff_t pos)
 {
 	spin_lock(&hdr->lock);
-	if (pos < hdr->io_start + hdr->good_bytes) {
-		set_bit(NFS_IOHDR_ERROR, &hdr->flags);
+	if (!test_and_set_bit(NFS_IOHDR_ERROR, &hdr->flags)
+	    || pos < hdr->io_start + hdr->good_bytes) {
 		clear_bit(NFS_IOHDR_EOF, &hdr->flags);
 		hdr->good_bytes = pos - hdr->io_start;
 		hdr->error = error;


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