NFSv4.1/pnfs: Fix a close/delegreturn hang when return-on-close is set

The helper pnfs_roc() has already verified that we have no delegations,
and no further open files, hence no outstanding I/O and it has marked
all the return-on-close lsegs as being invalid.
Furthermore, it sets the NFS_LAYOUT_RETURN bit, thus serialising the
close/delegreturn with all future layoutget calls on this inode.

The checks in pnfs_roc_drain() for valid layout segments are therefore
redundant: those cannot exist until another layoutget completes.
The other check for whether or not NFS_LAYOUT_RETURN is set, actually
causes a hang, since we already know that we hold that flag.

To fix, we therefore strip out all the functionality in pnfs_roc_drain()
except the retrieval of the barrier state, and then rename the function
accordingly.

Reported-by: Christoph Hellwig <hch@infradead.org>
Fixes: 5c4a79fb2b1c ("Don't prevent layoutgets when doing return-on-close")
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

1 files changed, 1 insertions, 23 deletions

diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 6151f39..6aabbb6 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -1141,25 +1141,14 @@ void pnfs_roc_set_barrier(struct inode *ino, u32 barrier)
 	spin_unlock(&ino->i_lock);
 }
 
-bool pnfs_roc_drain(struct inode *ino, u32 *barrier, struct rpc_task *task)
+void pnfs_roc_get_barrier(struct inode *ino, u32 *barrier)
 {
 	struct nfs_inode *nfsi = NFS_I(ino);
 	struct pnfs_layout_hdr *lo;
-	struct pnfs_layout_segment *lseg;
 	nfs4_stateid stateid;
 	u32 current_seqid;
-	bool layoutreturn = false;
 
 	spin_lock(&ino->i_lock);
-	list_for_each_entry(lseg, &nfsi->layout->plh_segs, pls_list) {
-		if (!test_bit(NFS_LSEG_ROC, &lseg->pls_flags))
-			continue;
-		if (test_bit(NFS_LSEG_VALID, &lseg->pls_flags))
-			continue;
-		rpc_sleep_on(&NFS_SERVER(ino)->roc_rpcwaitq, task, NULL);
-		spin_unlock(&ino->i_lock);
-		return true;
-	}
 	lo = nfsi->layout;
 	current_seqid = be32_to_cpu(lo->plh_stateid.seqid);
 
@@ -1168,18 +1157,7 @@ bool pnfs_roc_drain(struct inode *ino, u32 *barrier, struct rpc_task *task)
 	 */
 	*barrier = current_seqid + atomic_read(&lo->plh_outstanding);
 	stateid = lo->plh_stateid;
-	if (test_and_clear_bit(NFS_LAYOUT_RETURN_BEFORE_CLOSE,
-					   &lo->plh_flags))
-		layoutreturn = pnfs_prepare_layoutreturn(lo);
-	if (test_bit(NFS_LAYOUT_RETURN, &lo->plh_flags))
-		rpc_sleep_on(&NFS_SERVER(ino)->roc_rpcwaitq, task, NULL);
-
 	spin_unlock(&ino->i_lock);
-	if (layoutreturn) {
-		pnfs_send_layoutreturn(lo, stateid, IOMODE_ANY, false);
-		return true;
-	}
-	return false;
 }
 
 /*