From: Peter Staubach <staubach@redhat.com>
Subject: [PATCH RHEL-5] fcntl(F_SETLEASE, F_WRLCK) for a file on NFS always  returns EAGAIN
Date: Wed, 06 Jun 2007 10:40:19 -0400
Bugzilla: 216750
Message-Id: <4666C753.2090907@redhat.com>
Changelog: [fs] nfs does not support leases, send correct error


Hi.

Attached is a patch to address bz216750, "fcntl(F_SETLEASE, F_WRLCK)
for a file on NFS always returns EAGAIN".

The problem is that NFS does not support leases due to the lack of
appropriate protocol support.  However, a bogus error is returned
when an attempt is made to acquire a lease.  These changes modify
the system so that NFS, and any other file systems which want to
use the functionality, can notify the file system independent layer
that it does not support leases.  The file system independent layer
can then return an error indicating that the request was not valid
for the underlying file system.

These changes have been accepted into the -mm kernel.

   Thanx...

      ps

--- linux-2.6.18.i686/fs/nfs/super.c.org
+++ linux-2.6.18.i686/fs/nfs/super.c
@@ -520,6 +520,8 @@ static inline void nfs_initialise_sb(str
 
 	sb->s_magic = NFS_SUPER_MAGIC;
 
+	sb->s_flags |= MS_NO_LEASES;
+
 	/* We probably want something more informative here */
 	snprintf(sb->s_id, sizeof(sb->s_id),
 		 "%x:%x", MAJOR(sb->s_dev), MINOR(sb->s_dev));
--- linux-2.6.18.i686/fs/locks.c.org
+++ linux-2.6.18.i686/fs/locks.c
@@ -1486,6 +1486,9 @@ int fcntl_setlease(unsigned int fd, stru
 	struct inode *inode = dentry->d_inode;
 	int error;
 
+	if (IS_NO_LEASES(inode))
+		return -EINVAL;
+
 	if ((current->fsuid != inode->i_uid) && !capable(CAP_LEASE))
 		return -EACCES;
 	if (!S_ISREG(inode->i_mode))
--- linux-2.6.18.i686/include/linux/fs.h.org
+++ linux-2.6.18.i686/include/linux/fs.h
@@ -119,6 +119,7 @@ extern int dir_notify_enable;
 #define MS_PRIVATE	(1<<18)	/* change to private */
 #define MS_SLAVE	(1<<19)	/* change to slave */
 #define MS_SHARED	(1<<20)	/* change to shared */
+#define MS_NO_LEASES	(1<<21)	/* fs does not support leases */
 #define MS_ACTIVE	(1<<30)
 #define MS_NOUSER	(1<<31)
 
@@ -177,6 +178,7 @@ extern int dir_notify_enable;
 #define IS_NOCMTIME(inode)	((inode)->i_flags & S_NOCMTIME)
 #define IS_SWAPFILE(inode)	((inode)->i_flags & S_SWAPFILE)
 #define IS_PRIVATE(inode)	((inode)->i_flags & S_PRIVATE)
+#define IS_NO_LEASES(inode)	__IS_FLG(inode, MS_NO_LEASES)
 
 /* the read-only stuff doesn't really belong here, but any other place is
    probably as bad and I don't want to create yet another include file. */