Patch "nfsd: Make init_open_stateid() a bit more whole" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    nfsd: Make init_open_stateid() a bit more whole

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     nfsd-make-init_open_stateid-a-bit-more-whole.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 8c7245abda877d4689b3371db8ae2a4400d7d9ce Mon Sep 17 00:00:00 2001
From: Oleg Drokin <green@linuxhacker.ru>
Date: Tue, 14 Jun 2016 23:28:06 -0400
Subject: nfsd: Make init_open_stateid() a bit more whole

From: Oleg Drokin <green@linuxhacker.ru>

commit 8c7245abda877d4689b3371db8ae2a4400d7d9ce upstream.

Move the state selection logic inside from the caller,
always making it return correct stp to use.

Signed-off-by: J . Bruce Fields <bfields@fieldses.org>
Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/nfsd/nfs4state.c |   27 ++++++++++++---------------
 1 file changed, 12 insertions(+), 15 deletions(-)

--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -3420,13 +3420,14 @@ alloc_init_open_stateowner(unsigned int
 }
 
 static struct nfs4_ol_stateid *
-init_open_stateid(struct nfs4_ol_stateid *stp, struct nfs4_file *fp,
-		struct nfsd4_open *open)
+init_open_stateid(struct nfs4_file *fp, struct nfsd4_open *open)
 {
 
 	struct nfs4_openowner *oo = open->op_openowner;
 	struct nfs4_ol_stateid *retstp = NULL;
+	struct nfs4_ol_stateid *stp;
 
+	stp = open->op_stp;
 	/* We are moving these outside of the spinlocks to avoid the warnings */
 	mutex_init(&stp->st_mutex);
 	mutex_lock(&stp->st_mutex);
@@ -3437,6 +3438,8 @@ init_open_stateid(struct nfs4_ol_stateid
 	retstp = nfsd4_find_existing_open(fp, open);
 	if (retstp)
 		goto out_unlock;
+
+	open->op_stp = NULL;
 	atomic_inc(&stp->st_stid.sc_count);
 	stp->st_stid.sc_type = NFS4_OPEN_STID;
 	INIT_LIST_HEAD(&stp->st_locks);
@@ -3454,10 +3457,11 @@ out_unlock:
 	spin_unlock(&oo->oo_owner.so_client->cl_lock);
 	if (retstp) {
 		mutex_lock(&retstp->st_mutex);
-		/* Not that we need to, just for neatness */
+		/* To keep mutex tracking happy */
 		mutex_unlock(&stp->st_mutex);
+		stp = retstp;
 	}
-	return retstp;
+	return stp;
 }
 
 /*
@@ -4260,7 +4264,6 @@ nfsd4_process_open2(struct svc_rqst *rqs
 	struct nfs4_client *cl = open->op_openowner->oo_owner.so_client;
 	struct nfs4_file *fp = NULL;
 	struct nfs4_ol_stateid *stp = NULL;
-	struct nfs4_ol_stateid *swapstp = NULL;
 	struct nfs4_delegation *dp = NULL;
 	__be32 status;
 
@@ -4297,16 +4300,10 @@ nfsd4_process_open2(struct svc_rqst *rqs
 			goto out;
 		}
 	} else {
-		stp = open->op_stp;
-		open->op_stp = NULL;
-		/*
-		 * init_open_stateid() either returns a locked stateid
-		 * it found, or initializes and locks the new one we passed in
-		 */
-		swapstp = init_open_stateid(stp, fp, open);
-		if (swapstp) {
-			nfs4_put_stid(&stp->st_stid);
-			stp = swapstp;
+		/* stp is returned locked. */
+		stp = init_open_stateid(fp, open);
+		/* See if we lost the race to some other thread */
+		if (stp->st_access_bmap != 0) {
 			status = nfs4_upgrade_open(rqstp, fp, current_fh,
 						stp, open);
 			if (status) {


Patches currently in stable-queue which might be from green@linuxhacker.ru are

queue-4.4/nfsd-make-init_open_stateid-a-bit-more-whole.patch