From: Konstantin Khlebnikov <khlebnikov@openvz.org>
Date: Wed, 28 Mar 2012 21:42:54 +0000 (-0700)
Subject: radix-tree: use iterators in find_get_pages* functions
X-Git-Tag: v3.4-rc1~53^2~7
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0fc9d1040313047edf6a39fd4d7c7defdca97c62;p=pandora-kernel.git

radix-tree: use iterators in find_get_pages* functions

Replace radix_tree_gang_lookup_slot() and
radix_tree_gang_lookup_tag_slot() in page-cache lookup functions with
brand-new radix-tree direct iterating.  This avoids the double-scanning
and pointer copying.

Iterator don't stop after nr_pages page-get fails in a row, it continue
lookup till the radix-tree end.  Thus we can safely remove these restart
conditions.

Unfortunately, old implementation didn't forbid nr_pages == 0, this corner
case does not fit into new code, so the patch adds an extra check at the
beginning.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Tested-by: Hugh Dickins <hughd@google.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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