2013-04-05 23:38:53

by Todd Poynor

[permalink] [raw]
Subject: [PATCH RESEND] ext4: fixup 64-bit divides in 3.0-stable backport of upstream fix

Replace C division operators with div64_u64 for divides introduced in:
commit 503f4bdcc078e7abee273a85ce322de81b18a224
ext4: use atomic64_t for the per-flexbg free_clusters count

Specific to the 3.0-stable backport of the upstream patch.

Signed-off-by: Todd Poynor <[email protected]>
---
Re-send with linux-ext4 list cc'ed

3.0-stable backport has additional changes, including converting
blocks_per_flex and flexbg_free_blocks from int to ext4_fsblk_t (a
64-bit type), probably as a part of these additional changes mentioned
in the commit message:

[Backported for 3.0-stable. Renamed free_clusters back to free_blocks;
fixed a few more atomic_read's of free_blocks left in 3.0.]

Perhaps the better fix is to revert those additional changes and let
the ext4 folks figure out what to do about the remaining atomic_reads.


fs/ext4/ialloc.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index dd732c7..443ffb8 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -22,6 +22,7 @@
#include <linux/random.h>
#include <linux/bitops.h>
#include <linux/blkdev.h>
+#include <linux/math64.h>
#include <asm/byteorder.h>

#include "ext4.h"
@@ -356,7 +357,7 @@ static int find_group_flex(struct super_block *sb, struct inode *parent,

find_close_to_parent:
flexbg_free_blocks = atomic64_read(&flex_group[best_flex].free_blocks);
- flex_freeb_ratio = flexbg_free_blocks * 100 / blocks_per_flex;
+ flex_freeb_ratio = div64_u64(flexbg_free_blocks * 100, blocks_per_flex);
if (atomic_read(&flex_group[best_flex].free_inodes) &&
flex_freeb_ratio > free_block_ratio)
goto found_flexbg;
@@ -371,7 +372,7 @@ find_close_to_parent:
continue;

flexbg_free_blocks = atomic64_read(&flex_group[i].free_blocks);
- flex_freeb_ratio = flexbg_free_blocks * 100 / blocks_per_flex;
+ flex_freeb_ratio = div64_u64(flexbg_free_blocks * 100, blocks_per_flex);

if (flex_freeb_ratio > free_block_ratio &&
(atomic_read(&flex_group[i].free_inodes))) {
--
1.8.1.3