pNFS: Prevent the layout header refcount going to zero in pnfs_roc()
Ensure that we hold a reference to the layout header when processing
the pNFS return-on-close so that the refcount value does not inadvertently
go to zero.
Reported-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: stable@vger.kernel.org # v4.10+
Tested-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index c13e826..ee723aa 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -292,8 +292,11 @@ pnfs_detach_layout_hdr(struct pnfs_layout_hdr *lo)
void
pnfs_put_layout_hdr(struct pnfs_layout_hdr *lo)
{
- struct inode *inode = lo->plh_inode;
+ struct inode *inode;
+ if (!lo)
+ return;
+ inode = lo->plh_inode;
pnfs_layoutreturn_before_put_layout_hdr(lo);
if (refcount_dec_and_lock(&lo->plh_refcount, &inode->i_lock)) {
@@ -1241,10 +1244,12 @@ bool pnfs_roc(struct inode *ino,
spin_lock(&ino->i_lock);
lo = nfsi->layout;
if (!lo || !pnfs_layout_is_valid(lo) ||
- test_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags))
+ test_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags)) {
+ lo = NULL;
goto out_noroc;
+ }
+ pnfs_get_layout_hdr(lo);
if (test_bit(NFS_LAYOUT_RETURN_LOCK, &lo->plh_flags)) {
- pnfs_get_layout_hdr(lo);
spin_unlock(&ino->i_lock);
wait_on_bit(&lo->plh_flags, NFS_LAYOUT_RETURN,
TASK_UNINTERRUPTIBLE);
@@ -1312,10 +1317,12 @@ bool pnfs_roc(struct inode *ino,
struct pnfs_layoutdriver_type *ld = NFS_SERVER(ino)->pnfs_curr_ld;
if (ld->prepare_layoutreturn)
ld->prepare_layoutreturn(args);
+ pnfs_put_layout_hdr(lo);
return true;
}
if (layoutreturn)
pnfs_send_layoutreturn(lo, &stateid, iomode, true);
+ pnfs_put_layout_hdr(lo);
return false;
}