From: Andrew Morton <akpm@osdl.org>
Date: Sun, 30 Jul 2006 10:03:28 +0000 (-0700)
Subject: [PATCH] invalidate_bdev() speedup
X-Git-Tag: v2.6.18-rc4~130
X-Git-Url: http://ftp.safe.ca/?a=commitdiff_plain;h=0e1dfc66b6ec94984a4778132147a8aa36461d58;p=safe%2Fjmp%2Flinux-2.6

[PATCH] invalidate_bdev() speedup

We can immediately bail from invalidate_bdev() if the blockdev has no
pagecache.

This solves the huge IPI storms which hald is causing on the big ia64
machines when it polls CDROM drives.

Acked-by: Jes Sorensen <jes@sgi.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

diff --git a/fs/buffer.c b/fs/buffer.c
index 3660dcb..71649ef 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -470,13 +470,18 @@ out:
    pass does the actual I/O. */
 void invalidate_bdev(struct block_device *bdev, int destroy_dirty_buffers)
 {
+	struct address_space *mapping = bdev->bd_inode->i_mapping;
+
+	if (mapping->nrpages == 0)
+		return;
+
 	invalidate_bh_lrus();
 	/*
 	 * FIXME: what about destroy_dirty_buffers?
 	 * We really want to use invalidate_inode_pages2() for
 	 * that, but not until that's cleaned up.
 	 */
-	invalidate_inode_pages(bdev->bd_inode->i_mapping);
+	invalidate_inode_pages(mapping);
 }
 
 /*