[PATCH 4.19 126/131] pNFS/flexfiles: Fix list corruption if the mirror count changes

Sasha Levin
2020-06-29T20:15:42Z

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 e0fe9a0f1bf18..d8cba46a9395c 100644
--- a/fs/nfs/flexfilelayout/flexfilelayout.c
+++ b/fs/nfs/flexfilelayout/flexfilelayout.c
@@ -915,9 +915,8 @@ ff_layout_pg_init_write(struct nfs_pageio_descriptor *pgio,
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++) {
ds = nfs4_ff_layout_prepare_ds(pgio->pg_lseg, i, true);
@@ -936,11 +935,15 @@ ff_layout_pg_init_write(struct nfs_pageio_descriptor *pgio,
}

return;
-
+out_eagain:
+ pnfs_generic_pg_cleanup(pgio);
+ pgio->pg_error = -EAGAIN;
+ return;
out_mds:
pnfs_put_lseg(pgio->pg_lseg);
pgio->pg_lseg = NULL;
nfs_pageio_reset_write_mds(pgio);
+ pgio->pg_error = -EAGAIN;
}

static unsigned int
--
2.25.1