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authorAndy Adamson <andros@netapp.com>2013-05-08 16:21:18 -0400
committerTrond Myklebust <Trond.Myklebust@netapp.com>2013-05-08 17:19:32 -0400
commitc23266d532b4de796a346f57a66587c5db17d27e (patch)
treeff380244bcc16957bb0849cac47d5383a2b710af /fs/nfs
parentd497ab975141666e674e7bd8729e00095ec23c9d (diff)
downloadlinux-linaro-stable-c23266d532b4de796a346f57a66587c5db17d27e.tar.gz
NFS4.1 Fix data server connection race
Unlike meta data server mounts which support multiple mount points to the same server via struct nfs_server, data servers support a single connection. Concurrent calls to setup the data server connection can race where the first call allocates the nfs_client struct, and before the cache struct nfs_client pointer can be set, a second call also tries to setup the connection, finds the already allocated nfs_client, bumps the reference count, re-initializes the session,etc. This results in a hanging data server session after umount. Signed-off-by: Andy Adamson <andros@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Diffstat (limited to 'fs/nfs')
-rw-r--r--fs/nfs/nfs4filelayout.h2
-rw-r--r--fs/nfs/nfs4filelayoutdev.c26
2 files changed, 26 insertions, 2 deletions
diff --git a/fs/nfs/nfs4filelayout.h b/fs/nfs/nfs4filelayout.h
index b8da95548d3d..235ff952d3c8 100644
--- a/fs/nfs/nfs4filelayout.h
+++ b/fs/nfs/nfs4filelayout.h
@@ -70,6 +70,8 @@ struct nfs4_pnfs_ds {
struct list_head ds_addrs;
struct nfs_client *ds_clp;
atomic_t ds_count;
+ unsigned long ds_state;
+#define NFS4DS_CONNECTING 0 /* ds is establishing connection */
};
struct nfs4_file_layout_dsaddr {
diff --git a/fs/nfs/nfs4filelayoutdev.c b/fs/nfs/nfs4filelayoutdev.c
index 1fe284f01f8b..661a0f611215 100644
--- a/fs/nfs/nfs4filelayoutdev.c
+++ b/fs/nfs/nfs4filelayoutdev.c
@@ -775,6 +775,22 @@ nfs4_fl_select_ds_fh(struct pnfs_layout_segment *lseg, u32 j)
return flseg->fh_array[i];
}
+static void nfs4_wait_ds_connect(struct nfs4_pnfs_ds *ds)
+{
+ might_sleep();
+ wait_on_bit(&ds->ds_state, NFS4DS_CONNECTING,
+ nfs_wait_bit_killable, TASK_KILLABLE);
+}
+
+static void nfs4_clear_ds_conn_bit(struct nfs4_pnfs_ds *ds)
+{
+ smp_mb__before_clear_bit();
+ clear_bit(NFS4DS_CONNECTING, &ds->ds_state);
+ smp_mb__after_clear_bit();
+ wake_up_bit(&ds->ds_state, NFS4DS_CONNECTING);
+}
+
+
struct nfs4_pnfs_ds *
nfs4_fl_prepare_ds(struct pnfs_layout_segment *lseg, u32 ds_idx)
{
@@ -791,16 +807,22 @@ nfs4_fl_prepare_ds(struct pnfs_layout_segment *lseg, u32 ds_idx)
filelayout_mark_devid_invalid(devid);
return NULL;
}
+ if (ds->ds_clp)
+ return ds;
- if (!ds->ds_clp) {
+ if (test_and_set_bit(NFS4DS_CONNECTING, &ds->ds_state) == 0) {
struct nfs_server *s = NFS_SERVER(lseg->pls_layout->plh_inode);
int err;
err = nfs4_ds_connect(s, ds);
if (err) {
nfs4_mark_deviceid_unavailable(devid);
- return NULL;
+ ds = NULL;
}
+ nfs4_clear_ds_conn_bit(ds);
+ } else {
+ /* Either ds is connected, or ds is NULL */
+ nfs4_wait_ds_connect(ds);
}
return ds;
}