[PATCH] remove lock_kernel() from file_ops.flush()

Rework the file_ops.flush() API sothat it is no longer called under
lock_kernel().  Push lock_kernel() down to all impementations except CIFS,
which doesn't want it.

Documentation/filesystems/Locking

@@ -318,7 +318,7 @@ poll:		no
 ioctl:		yes	(see below)
 mmap:		no
 open:		maybe	(see below)
-flush:		yes
+flush:		no
 release:	no
 fsync:		yes	(see below)
 fasync:		yes	(see below)

fs/coda/file.c

@@ -153,19 +153,22 @@ int coda_flush(struct file *coda_file)
 	struct inode *coda_inode;
 	int err = 0, fcnt;
 
+	lock_kernel();
+
 	coda_vfs_stat.flush++;
 
 	/* last close semantics */
 	fcnt = file_count(coda_file);
-	if (fcnt > 1) return 0;
+	if (fcnt > 1)
+		goto out;
 
 	/* No need to make an upcall when we have not made any modifications
 	 * to the file */
 	if ((coda_file->f_flags & O_ACCMODE) == O_RDONLY)
-		return 0;
+		goto out;
 
 	if (use_coda_close)
-		return 0;
+		goto out;
 
 	cfi = CODA_FTOC(coda_file);
 	BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
@@ -180,6 +183,8 @@ int coda_flush(struct file *coda_file)
 		err = 0;
 	}
 
+out:
+	unlock_kernel();
 	return err;
 }
 

fs/nfs/file.c

@@ -104,11 +104,13 @@ nfs_file_flush(struct file *file)
 
 	dfprintk(VFS, "nfs: flush(%s/%ld)\n", inode->i_sb->s_id, inode->i_ino);
 
+	lock_kernel();
 	status = nfs_wb_file(inode, file);
 	if (!status) {
 		status = file->f_error;
 		file->f_error = 0;
 	}
+	unlock_kernel();
 	return status;
 }
 

fs/open.c

@@ -952,11 +952,8 @@ int filp_close(struct file *filp, fl_owner_t id)
 		return 0;
 	}
 	retval = 0;
-	if (filp->f_op && filp->f_op->flush) {
-		lock_kernel();
+	if (filp->f_op && filp->f_op->flush)
 		retval = filp->f_op->flush(filp);
-		unlock_kernel();
-	}
 	dnotify_flush(filp, id);
 	locks_remove_posix(filp, id);
 	fput(filp);