aboutsummaryrefslogtreecommitdiff
path: root/fs
diff options
context:
space:
mode:
authorTrond Myklebust <trond.myklebust@primarydata.com>2017-07-20 17:00:02 -0400
committerAnna Schumaker <Anna.Schumaker@Netapp.com>2017-07-21 14:08:45 -0400
commit1ebf980127924c639e2b85c08468311ba1c95b70 (patch)
tree514331ff7257270cc81f6963cc483b91cd0f0530 /fs
parentecbb903c56745d59c301db26dd7d8b74b520eb84 (diff)
downloadlinux-stericsson-1ebf980127924c639e2b85c08468311ba1c95b70.tar.gz
NFS/filelayout: Fix racy setting of fl->dsaddr in filelayout_check_deviceid()
We must set fl->dsaddr once, and once only, even if there are multiple processes calling filelayout_check_deviceid() for the same layout segment. Reported-by: Olga Kornievskaia <kolga@netapp.com> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/nfs/filelayout/filelayout.c13
1 files changed, 11 insertions, 2 deletions
diff --git a/fs/nfs/filelayout/filelayout.c b/fs/nfs/filelayout/filelayout.c
index 080fc6b278bd..44c638b7876c 100644
--- a/fs/nfs/filelayout/filelayout.c
+++ b/fs/nfs/filelayout/filelayout.c
@@ -542,6 +542,10 @@ filelayout_check_deviceid(struct pnfs_layout_hdr *lo,
struct nfs4_file_layout_dsaddr *dsaddr;
int status = -EINVAL;
+ /* Is the deviceid already set? If so, we're good. */
+ if (fl->dsaddr != NULL)
+ return 0;
+
/* find and reference the deviceid */
d = nfs4_find_get_deviceid(NFS_SERVER(lo->plh_inode), &fl->deviceid,
lo->plh_lc_cred, gfp_flags);
@@ -553,8 +557,6 @@ filelayout_check_deviceid(struct pnfs_layout_hdr *lo,
if (filelayout_test_devid_unavailable(&dsaddr->id_node))
goto out_put;
- fl->dsaddr = dsaddr;
-
if (fl->first_stripe_index >= dsaddr->stripe_count) {
dprintk("%s Bad first_stripe_index %u\n",
__func__, fl->first_stripe_index);
@@ -570,6 +572,13 @@ filelayout_check_deviceid(struct pnfs_layout_hdr *lo,
goto out_put;
}
status = 0;
+
+ /*
+ * Atomic compare and xchange to ensure we don't scribble
+ * over a non-NULL pointer.
+ */
+ if (cmpxchg(&fl->dsaddr, NULL, dsaddr) != NULL)
+ goto out_put;
out:
return status;
out_put: