[PATCH 0/5] Enable extra optimisations on fcntl(F_UNLCK) requests on NFS

[PATCH 0/5] Enable extra optimisations on fcntl(F_UNLCK) requests on NFS

[Trond Myklebust]

Hi,

The following set of patches enables the NFS client to determine more
accurately whether or not it needs to send an NLM/NFSv4 unlock request
if the process has outstanding posix or flock locks:
The current heuristic just assumes that if inode->i_flock is non-null, then
we should always spam the server with an unlock request upon close().

The patchset introduces a new flag to the posix_lock_file()/flock_lock_file()
interfaces that tells them to return -ENOENT if an F_UNLCK request results in
no action.

Cheers,
  Trond

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[PATCH 1/5] VFS: Allow caller to determine if BSD or posix locks were actually freed

[Trond Myklebust]

From: Trond Myklebust <Trond.Myklebust@netapp.com>

Change posix_lock_file_conf(), and flock_lock_file() so that if called
with an F_UNLCK argument, and the FL_EXISTS flag they will indicate
whether or not any locks were actually freed by returning 0 or -ENOENT.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
---

 fs/locks.c         |   18 ++++++++++++++++--
 include/linux/fs.h |    1 +
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/fs/locks.c b/fs/locks.c
index 1ad29c9..50cb0a2 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -725,6 +725,10 @@ next_task:
 /* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
  * at the head of the list, but that's secret knowledge known only to
  * flock_lock_file and posix_lock_file.
+ *
+ * Note that if called with an FL_EXISTS argument, the caller may determine
+ * whether or not a lock was successfully freed by testing the return
+ * value for -ENOENT.
  */
 static int flock_lock_file(struct file *filp, struct file_lock *request)
 {
@@ -750,8 +754,11 @@ static int flock_lock_file(struct file *
 		break;
 	}
 
-	if (request->fl_type == F_UNLCK)
+	if (request->fl_type == F_UNLCK) {
+		if ((request->fl_flags & FL_EXISTS) && !found)
+			error = -ENOENT;
 		goto out;
+	}
 
 	error = -ENOMEM;
 	new_fl = locks_alloc_lock();
@@ -948,8 +955,11 @@ static int __posix_lock_file_conf(struct
 
 	error = 0;
 	if (!added) {
-		if (request->fl_type == F_UNLCK)
+		if (request->fl_type == F_UNLCK) {
+			if (request->fl_flags & FL_EXISTS)
+				error = -ENOENT;
 			goto out;
+		}
 
 		if (!new_fl) {
 			error = -ENOLCK;
@@ -996,6 +1006,10 @@ static int __posix_lock_file_conf(struct
  * Add a POSIX style lock to a file.
  * We merge adjacent & overlapping locks whenever possible.
  * POSIX locks are sorted by owner task, then by starting address
+ *
+ * Note that if called with an FL_EXISTS argument, the caller may determine
+ * whether or not a lock was successfully freed by testing the return
+ * value for -ENOENT.
  */
 int posix_lock_file(struct file *filp, struct file_lock *fl)
 {
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 2d8b348..31b1f6f 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -682,6 +682,7 @@ #endif
 #define FL_POSIX	1
 #define FL_FLOCK	2
 #define FL_ACCESS	8	/* not trying to lock, just looking */
+#define FL_EXISTS	16	/* when unlocking, test for existence */
 #define FL_LEASE	32	/* lease held on this file */
 #define FL_CLOSE	64	/* unlock on close */
 #define FL_SLEEP	128	/* A blocking lock */

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[PATCH 2/5] NLM, NFSv4: Don't put UNLOCK requests on the wire unless we hold a lock

[Trond Myklebust]

From: Trond Myklebust <Trond.Myklebust@netapp.com>

Use the new behaviour of {flock,posix}_file_lock(F_UNLCK) to determine if
we held a lock, and only send the RPC request to the server if this was the
case.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
---

 fs/lockd/clntproc.c |   18 ++++++++++--------
 fs/nfs/nfs4proc.c   |   31 ++++++++++++-------------------
 2 files changed, 22 insertions(+), 27 deletions(-)

diff --git a/fs/lockd/clntproc.c b/fs/lockd/clntproc.c
index 4db6209..e6dd725 100644
--- a/fs/lockd/clntproc.c
+++ b/fs/lockd/clntproc.c
@@ -455,7 +455,7 @@ static void nlmclnt_locks_init_private(s
 	fl->fl_ops = &nlmclnt_lock_ops;
 }
 
-static void do_vfs_lock(struct file_lock *fl)
+static int do_vfs_lock(struct file_lock *fl)
 {
 	int res = 0;
 	switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) {
@@ -468,9 +468,7 @@ static void do_vfs_lock(struct file_lock
 		default:
 			BUG();
 	}
-	if (res < 0)
-		printk(KERN_WARNING "%s: VFS is out of sync with lock manager!\n",
-				__FUNCTION__);
+	return res;
 }
 
 /*
@@ -542,7 +540,8 @@ again:
 		}
 		fl->fl_flags |= FL_SLEEP;
 		/* Ensure the resulting lock will get added to granted list */
-		do_vfs_lock(fl);
+		if (do_vfs_lock(fl) < 0)
+			printk(KERN_WARNING "%s: VFS is out of sync with lock manager!\n", __FUNCTION__);
 		up_read(&host->h_rwsem);
 	}
 	status = nlm_stat_to_errno(resp->status);
@@ -607,15 +606,19 @@ nlmclnt_unlock(struct nlm_rqst *req, str
 {
 	struct nlm_host	*host = req->a_host;
 	struct nlm_res	*resp = &req->a_res;
-	int		status;
+	int status = 0;
 
 	/*
 	 * Note: the server is supposed to either grant us the unlock
 	 * request, or to deny it with NLM_LCK_DENIED_GRACE_PERIOD. In either
 	 * case, we want to unlock.
 	 */
+	fl->fl_flags |= FL_EXISTS;
 	down_read(&host->h_rwsem);
-	do_vfs_lock(fl);
+	if (do_vfs_lock(fl) == -ENOENT) {
+		up_read(&host->h_rwsem);
+		goto out;
+	}
 	up_read(&host->h_rwsem);
 
 	if (req->a_flags & RPC_TASK_ASYNC)
@@ -625,7 +628,6 @@ nlmclnt_unlock(struct nlm_rqst *req, str
 	if (status < 0)
 		goto out;
 
-	status = 0;
 	if (resp->status == NLM_LCK_GRANTED)
 		goto out;
 
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index b4916b0..b8c6375 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -3144,9 +3144,6 @@ static int do_vfs_lock(struct file *file
 		default:
 			BUG();
 	}
-	if (res < 0)
-		printk(KERN_WARNING "%s: VFS is out of sync with lock manager!\n",
-				__FUNCTION__);
 	return res;
 }
 
@@ -3258,8 +3255,6 @@ static struct rpc_task *nfs4_do_unlck(st
 		return ERR_PTR(-ENOMEM);
 	}
 
-	/* Unlock _before_ we do the RPC call */
-	do_vfs_lock(fl->fl_file, fl);
 	return rpc_run_task(NFS_CLIENT(lsp->ls_state->inode), RPC_TASK_ASYNC, &nfs4_locku_ops, data);
 }
 
@@ -3270,30 +3265,28 @@ static int nfs4_proc_unlck(struct nfs4_s
 	struct rpc_task *task;
 	int status = 0;
 
-	/* Is this a delegated lock? */
-	if (test_bit(NFS_DELEGATED_STATE, &state->flags))
-		goto out_unlock;
-	/* Is this open_owner holding any locks on the server? */
-	if (test_bit(LK_STATE_IN_USE, &state->flags) == 0)
-		goto out_unlock;
-
 	status = nfs4_set_lock_state(state, request);
+	/* Unlock _before_ we do the RPC call */
+	request->fl_flags |= FL_EXISTS;
+	if (do_vfs_lock(request->fl_file, request) == -ENOENT)
+		goto out;
 	if (status != 0)
-		goto out_unlock;
+		goto out;
+	/* Is this a delegated lock? */
+	if (test_bit(NFS_DELEGATED_STATE, &state->flags))
+		goto out;
 	lsp = request->fl_u.nfs4_fl.owner;
-	status = -ENOMEM;
 	seqid = nfs_alloc_seqid(&lsp->ls_seqid);
+	status = -ENOMEM;
 	if (seqid == NULL)
-		goto out_unlock;
+		goto out;
 	task = nfs4_do_unlck(request, request->fl_file->private_data, lsp, seqid);
 	status = PTR_ERR(task);
 	if (IS_ERR(task))
-		goto out_unlock;
+		goto out;
 	status = nfs4_wait_for_completion_rpc_task(task);
 	rpc_release_task(task);
-	return status;
-out_unlock:
-	do_vfs_lock(request->fl_file, request);
+out:
 	return status;
 }
 

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[PATCH 3/5] NFSv4: Ensure nfs4_lock_expired() caches delegated locks

[Trond Myklebust]

From: Trond Myklebust <Trond.Myklebust@netapp.com>

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
---

 fs/nfs/nfs4proc.c |    8 +++++---
 1 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index b8c6375..8bdfe3f 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -3454,10 +3454,10 @@ static int nfs4_lock_reclaim(struct nfs4
 	struct nfs4_exception exception = { };
 	int err;
 
-	/* Cache the lock if possible... */
-	if (test_bit(NFS_DELEGATED_STATE, &state->flags))
-		return 0;
 	do {
+		/* Cache the lock if possible... */
+		if (test_bit(NFS_DELEGATED_STATE, &state->flags) != 0)
+			return 0;
 		err = _nfs4_do_setlk(state, F_SETLK, request, 1);
 		if (err != -NFS4ERR_DELAY)
 			break;
@@ -3476,6 +3476,8 @@ static int nfs4_lock_expired(struct nfs4
 	if (err != 0)
 		return err;
 	do {
+		if (test_bit(NFS_DELEGATED_STATE, &state->flags) != 0)
+			return 0;
 		err = _nfs4_do_setlk(state, F_SETLK, request, 0);
 		if (err != -NFS4ERR_DELAY)
 			break;

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[PATCH 4/5] VFS: Add support for the FL_ACCESS flag to flock_lock_file()

[Trond Myklebust]

From: Trond Myklebust <Trond.Myklebust@netapp.com>

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
---

 fs/locks.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/fs/locks.c b/fs/locks.c
index 50cb0a2..b0b41a6 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -739,6 +739,8 @@ static int flock_lock_file(struct file *
 	int found = 0;
 
 	lock_kernel();
+	if (request->fl_flags & FL_ACCESS)
+		goto find_conflict;
 	for_each_lock(inode, before) {
 		struct file_lock *fl = *before;
 		if (IS_POSIX(fl))
@@ -771,6 +773,7 @@ static int flock_lock_file(struct file *
 	if (found)
 		cond_resched();
 
+find_conflict:
 	for_each_lock(inode, before) {
 		struct file_lock *fl = *before;
 		if (IS_POSIX(fl))
@@ -784,6 +787,8 @@ static int flock_lock_file(struct file *
 			locks_insert_block(fl, request);
 		goto out;
 	}
+	if (request->fl_flags & FL_ACCESS)
+		goto out;
 	locks_copy_lock(new_fl, request);
 	locks_insert_lock(&inode->i_flock, new_fl);
 	new_fl = NULL;

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[PATCH 5/5] NLM, NFSv4: Wait on local locks before we put RPC calls on the wire

[Trond Myklebust]

From: Trond Myklebust <Trond.Myklebust@netapp.com>

Use FL_ACCESS flag to test and/or wait for local locks before we try
requesting a lock from the server

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
---

 fs/lockd/clntproc.c |    8 +++++++-
 fs/nfs/nfs4proc.c   |   35 ++++++++++++++++++++++++-----------
 2 files changed, 31 insertions(+), 12 deletions(-)

diff --git a/fs/lockd/clntproc.c b/fs/lockd/clntproc.c
index e6dd725..ad089d0 100644
--- a/fs/lockd/clntproc.c
+++ b/fs/lockd/clntproc.c
@@ -497,6 +497,7 @@ nlmclnt_lock(struct nlm_rqst *req, struc
 	struct nlm_host	*host = req->a_host;
 	struct nlm_res	*resp = &req->a_res;
 	struct nlm_wait *block = NULL;
+	unsigned char fl_flags = fl->fl_flags;
 	int status = -ENOLCK;
 
 	if (!host->h_monitored && nsm_monitor(host) < 0) {
@@ -504,6 +505,10 @@ nlmclnt_lock(struct nlm_rqst *req, struc
 					host->h_name);
 		goto out;
 	}
+	fl->fl_flags |= FL_ACCESS;
+	status = do_vfs_lock(fl);
+	if (status < 0)
+		goto out;
 
 	block = nlmclnt_prepare_block(host, fl);
 again:
@@ -538,8 +543,8 @@ again:
 			up_read(&host->h_rwsem);
 			goto again;
 		}
-		fl->fl_flags |= FL_SLEEP;
 		/* Ensure the resulting lock will get added to granted list */
+		fl->fl_flags = fl_flags | FL_SLEEP;
 		if (do_vfs_lock(fl) < 0)
 			printk(KERN_WARNING "%s: VFS is out of sync with lock manager!\n", __FUNCTION__);
 		up_read(&host->h_rwsem);
@@ -552,6 +557,7 @@ out_unblock:
 		nlmclnt_cancel(host, req->a_args.block, fl);
 out:
 	nlm_release_call(req);
+	fl->fl_flags = fl_flags;
 	return status;
 }
 
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 8bdfe3f..e6ee97f 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -3489,29 +3489,42 @@ static int nfs4_lock_expired(struct nfs4
 static int _nfs4_proc_setlk(struct nfs4_state *state, int cmd, struct file_lock *request)
 {
 	struct nfs4_client *clp = state->owner->so_client;
+	unsigned char fl_flags = request->fl_flags;
 	int status;
 
 	/* Is this a delegated open? */
-	if (NFS_I(state->inode)->delegation_state != 0) {
-		/* Yes: cache locks! */
-		status = do_vfs_lock(request->fl_file, request);
-		/* ...but avoid races with delegation recall... */
-		if (status < 0 || test_bit(NFS_DELEGATED_STATE, &state->flags))
-			return status;
-	}
-	down_read(&clp->cl_sem);
 	status = nfs4_set_lock_state(state, request);
 	if (status != 0)
 		goto out;
+	request->fl_flags |= FL_ACCESS;
+	status = do_vfs_lock(request->fl_file, request);
+	if (status < 0)
+		goto out;
+	down_read(&clp->cl_sem);
+	if (test_bit(NFS_DELEGATED_STATE, &state->flags)) {
+		struct nfs_inode *nfsi = NFS_I(state->inode);
+		/* Yes: cache locks! */
+		down_read(&nfsi->rwsem);
+		/* ...but avoid races with delegation recall... */
+		if (test_bit(NFS_DELEGATED_STATE, &state->flags)) {
+			request->fl_flags = fl_flags & ~FL_SLEEP;
+			status = do_vfs_lock(request->fl_file, request);
+			up_read(&nfsi->rwsem);
+			goto out_unlock;
+		}
+		up_read(&nfsi->rwsem);
+	}
 	status = _nfs4_do_setlk(state, cmd, request, 0);
 	if (status != 0)
-		goto out;
+		goto out_unlock;
 	/* Note: we always want to sleep here! */
-	request->fl_flags |= FL_SLEEP;
+	request->fl_flags = fl_flags | FL_SLEEP;
 	if (do_vfs_lock(request->fl_file, request) < 0)
 		printk(KERN_WARNING "%s: VFS is out of sync with lock manager!\n", __FUNCTION__);
-out:
+out_unlock:
 	up_read(&clp->cl_sem);
+out:
+	request->fl_flags = fl_flags;
 	return status;
 }
 

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