[PATCH] ext4: page_cache pages over pinned in ext4_mb_free_metadata()

[jing zhang <zj.barak@gmail.com>]

From: Jing Zhang <zj.barak@gmail.com>

Date: Wed Mar 24 20:38:48     2010

The function, ext4_mb_free_metadata(), is called after
     ext4_mb_load_buddy(sb, block_group, &e4b);
and before
     ext4_mb_release_desc(&e4b);
in the function, ext4_mb_free_blocks(), so the bd_bitmap_page and
bd_buddy_page of e4b are well managed.

If for special purpose, page_cache_get() is issued on these two pages,
there should also be page_cache_release() issued correspondingly, or
the two pages are over pinned.

Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Andreas Dilger <adilger@sun.com>
Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: Jing Zhang <zj.barak@gmail.com>

---

--- linux-2.6.32/fs/ext4/mballoc.c	2009-12-03 11:51:22.000000000 +0800
+++ ext4_mm_leak/mballoc6.c	2010-03-24 20:31:52.000000000 +0800
@@ -4361,15 +4361,6 @@ ext4_mb_free_metadata(handle_t *handle,
 	new_node = &new_entry->node;
 	block = new_entry->start_blk;

-	if (!*n) {
-		/* first free block exent. We need to
-		   protect buddy cache from being freed,
-		 * otherwise we'll refresh it from
-		 * on-disk bitmap and lose not-yet-available
-		 * blocks */
-		page_cache_get(e4b->bd_buddy_page);
-		page_cache_get(e4b->bd_bitmap_page);
-	}
 	while (*n) {
 		parent = *n;
 		entry = rb_entry(parent, struct ext4_free_data, node);