From: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Date: Tue, 8 Jan 2008 23:32:41 +0000 (-0800)
Subject: fat: optimize fat_count_free_clusters()
X-Git-Tag: v2.6.24-rc8~67
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9f966be8996f2829406324c68e4c67c2d64d864b;p=pandora-kernel.git

fat: optimize fat_count_free_clusters()

On large partition, scanning the free clusters is very slow if users
doesn't use "usefree" option.

For optimizing it, this patch uses sb_breadahead() to read of FAT
sectors. On some user's 15GB partition, this patch improved it very
much (1min => 600ms).

The following is the result of 2GB partition on my machine.

without patch:
	root@devron (/)# time df -h > /dev/null

	real    0m1.202s
	user    0m0.000s
	sys     0m0.440s

with patch:
	root@devron (/)# time df -h > /dev/null

	real    0m0.378s
	user    0m0.012s
	sys     0m0.168s

Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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