nfs41: serialize first layoutget of a file
Per RFC 5661 Errata 3208:
| A client MAY always forget its layout state and associated
| layout stateid at any time (See also section 12.5.5.1).
| In such case, the client MUST use a non-layout stateid for the next
| LAYOUTGET operation. This will signal the server that the client has
| no more layouts on the file and its respective layout state can be
| released before issuing a new layout in response to LAYOUTGET.
In order to make such a signal unique to server, client needs to serialize
all layoutgets using non-layout stateid. We implement this by serializing
layoutgets when client has no layout segments at hand.
Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Tom Haynes <Thomas.Haynes@primarydata.com>
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index fa00b56..7e1bac1 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -1288,6 +1288,7 @@
struct nfs_client *clp = server->nfs_client;
struct pnfs_layout_hdr *lo;
struct pnfs_layout_segment *lseg = NULL;
+ bool first;
if (!pnfs_enabled_sb(NFS_SERVER(ino)))
goto out;
@@ -1295,6 +1296,8 @@
if (pnfs_within_mdsthreshold(ctx, ino, iomode))
goto out;
+lookup_again:
+ first = false;
spin_lock(&ino->i_lock);
lo = pnfs_find_alloc_layout(ino, ctx, gfp_flags);
if (lo == NULL) {
@@ -1312,10 +1315,27 @@
if (pnfs_layout_io_test_failed(lo, iomode))
goto out_unlock;
- /* Check to see if the layout for the given range already exists */
- lseg = pnfs_find_lseg(lo, &arg);
- if (lseg)
- goto out_unlock;
+ first = list_empty(&lo->plh_segs);
+ if (first) {
+ /* The first layoutget for the file. Need to serialize per
+ * RFC 5661 Errata 3208.
+ */
+ if (test_and_set_bit(NFS_LAYOUT_FIRST_LAYOUTGET,
+ &lo->plh_flags)) {
+ spin_unlock(&ino->i_lock);
+ wait_on_bit(&lo->plh_flags, NFS_LAYOUT_FIRST_LAYOUTGET,
+ TASK_UNINTERRUPTIBLE);
+ pnfs_put_layout_hdr(lo);
+ goto lookup_again;
+ }
+ } else {
+ /* Check to see if the layout for the given range
+ * already exists
+ */
+ lseg = pnfs_find_lseg(lo, &arg);
+ if (lseg)
+ goto out_unlock;
+ }
if (pnfs_layoutgets_blocked(lo, 0))
goto out_unlock;
@@ -1343,6 +1363,13 @@
lseg = send_layoutget(lo, ctx, &arg, gfp_flags);
atomic_dec(&lo->plh_outstanding);
out_put_layout_hdr:
+ if (first) {
+ unsigned long *bitlock = &lo->plh_flags;
+
+ clear_bit_unlock(NFS_LAYOUT_FIRST_LAYOUTGET, bitlock);
+ smp_mb__after_atomic();
+ wake_up_bit(bitlock, NFS_LAYOUT_FIRST_LAYOUTGET);
+ }
pnfs_put_layout_hdr(lo);
out:
dprintk("%s: inode %s/%llu pNFS layout segment %s for "
