[PATCH 3.12 55/84] NFS: nfs_set_pgio_error sometimes misses errors

[Jiri Slaby]

From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>

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

===============

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@xxxxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
 fs/nfs/pagelist.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 27d7f2742592..11763ce73709 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -60,8 +60,8 @@ 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;
-- 
2.6.0

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/