[PATCH 5.7 259/265] pNFS/flexfiles: Fix list corruption if the mirror count changes

Sasha Levin
2020-06-29T21:52:25Z

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

commit 8b04013737341442ed914b336cde866b902664ae upstream.

If the mirror count changes in the new layout we pick up inside
ff_layout_pg_init_write(), then we can end up adding the
request to the wrong mirror and corrupting the mirror->pg_list.

Fixes: d600ad1f2bdb ("NFS41: pop some layoutget errors to application")
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/nfs/flexfilelayout/flexfilelayout.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/fs/nfs/flexfilelayout/flexfilelayout.c b/fs/nfs/flexfilelayout/flexfilelayout.c
index 7d399f72ebbbf..de03e440b7eef 100644
--- a/fs/nfs/flexfilelayout/flexfilelayout.c
+++ b/fs/nfs/flexfilelayout/flexfilelayout.c
@@ -907,9 +907,8 @@ retry:
goto out_mds;

/* Use a direct mapping of ds_idx to pgio mirror_idx */
- if (WARN_ON_ONCE(pgio->pg_mirror_count !=
- FF_LAYOUT_MIRROR_COUNT(pgio->pg_lseg)))
- goto out_mds;
+ if (pgio->pg_mirror_count != FF_LAYOUT_MIRROR_COUNT(pgio->pg_lseg))
+ goto out_eagain;

for (i = 0; i < pgio->pg_mirror_count; i++) {
mirror = FF_LAYOUT_COMP(pgio->pg_lseg, i);
@@ -931,7 +930,10 @@ retry:
(NFS_MOUNT_SOFT|NFS_MOUNT_SOFTERR))
pgio->pg_maxretrans = io_maxretrans;
return;
-
+out_eagain:
+ pnfs_generic_pg_cleanup(pgio);
+ pgio->pg_error = -EAGAIN;
+ return;
out_mds:
trace_pnfs_mds_fallback_pg_init_write(pgio->pg_inode,
0, NFS4_MAX_UINT64, IOMODE_RW,
@@ -941,6 +943,7 @@ out_mds:
pgio->pg_lseg = NULL;
pgio->pg_maxretrans = 0;
nfs_pageio_reset_write_mds(pgio);
+ pgio->pg_error = -EAGAIN;
}

static unsigned int
--
2.25.1