[PATCH 3.16.y-ckt 040/133] NFS: nfs_set_pgio_error sometimes misses errors

From: Luis Henriques
Date: Wed Sep 30 2015 - 06:28:38 EST

3.16.7-ckt18 -stable review patch. If anyone has any objections, please let me know.


From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>

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: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
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 54d049f930f7..2bd81a6d308c 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -63,8 +63,8 @@ EXPORT_SYMBOL_GPL(nfs_pgheader_init);
void nfs_set_pgio_error(struct nfs_pgio_header *hdr, int error, loff_t pos)
- 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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