From: Marc Eshel <eshel@almaden.ibm.com>
Subject: [patch] flock/fcntl bug
Date: Wed, 15 Dec 2004 10:15:41 -0800
Message-ID: <OF05A12F51.B9794B13-ON88256F6B.0062DC68-88256F6B.0064504D@us.ibm.com>
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To: nfs@lists.sourceforge.net
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To fs/locks.c owner

There is a bug in the unlock of posix locks. If there is an flock held on a
file that is being closed an unneeded call is made to the file system to do
an fcntl unlock. In the case of NFS it will be a call to the NFS server
which is expensive. This patch just checks that it is a posix lock before
calling the file system.

Marc.


--- linux-2.6.10-rc2.orig/fs/locks.c      2004-11-14 17:28:31.000000000
-0800
+++ linux-2.6.10-rc2-locks/fs/locks.c     2004-12-15 09:44:25.857512320
-0800
@@ -1846,11 +1962,6 @@ void locks_remove_posix(struct file *fil
  lock.fl_ops = NULL;
  lock.fl_lmops = NULL;

-     if (filp->f_op && filp->f_op->lock != NULL) {
-           filp->f_op->lock(filp, F_SETLK, &lock);
-           goto out;
-     }
-
  /* Can't use posix_lock_file here; we need to remove it no matter
   * which pid we have.
   */
@@ -1858,6 +1969,11 @@ void locks_remove_posix(struct file *fil
  while (*before != NULL) {
   struct file_lock *fl = *before;
   if (IS_POSIX(fl) && posix_same_owner(fl, &lock)) {
+                 if (filp->f_op && filp->f_op->lock != NULL) {
+                       unlock_kernel();
+                       filp->f_op->lock(filp, F_SETLK, &lock);
+                       goto out;
+                 }
    locks_delete_lock(before);
    continue;
   }


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