Subject: + block-do-not-call-sector_div-with-a-64-bit-divisor.patch added to -mm tree
To: geert@xxxxxxxxxxxxxx,axboe@xxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Mon, 04 Nov 2013 13:01:58 -0800
The patch titled
Subject: block: do not call sector_div() with a 64-bit divisor
has been added to the -mm tree. Its filename is
block-do-not-call-sector_div-with-a-64-bit-divisor.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/block-do-not-call-sector_div-with-a-64-bit-divisor.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/block-do-not-call-sector_div-with-a-64-bit-divisor.patch
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From: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Subject: block: do not call sector_div() with a 64-bit divisor
do_div() (called by sector_div() if CONFIG_LBDAF=y) is meant for divisions
of 64-bit number by 32-bit numbers. Passing 64-bit divisor types caused
issues in the past on 32-bit platforms, cfr. commit ea077b1b96e073ea
("m68k: Truncate base in do_div()").
As queue_limits.max_discard_sectors and .discard_granularity are unsigned
int, max_discard_sectors and granularity should be unsigned int. As
bdev_discard_alignment() returns int, alignment should be int. Now 2
calls to sector_div() can be replaced by 32-bit arithmetic:
- The 64-bit modulo operation can become a 32-bit modulo operation,
- The 64-bit division and multiplication can be replaced by a 32-bit
modulo operation and a subtraction.
Signed-off-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
block/blk-lib.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)
diff -puN block/blk-lib.c~block-do-not-call-sector_div-with-a-64-bit-divisor block/blk-lib.c
--- a/block/blk-lib.c~block-do-not-call-sector_div-with-a-64-bit-divisor
+++ a/block/blk-lib.c
@@ -43,8 +43,8 @@ int blkdev_issue_discard(struct block_de
DECLARE_COMPLETION_ONSTACK(wait);
struct request_queue *q = bdev_get_queue(bdev);
int type = REQ_WRITE | REQ_DISCARD;
- sector_t max_discard_sectors;
- sector_t granularity, alignment;
+ unsigned int max_discard_sectors, granularity;
+ int alignment;
struct bio_batch bb;
struct bio *bio;
int ret = 0;
@@ -58,16 +58,14 @@ int blkdev_issue_discard(struct block_de
/* Zero-sector (unknown) and one-sector granularities are the same. */
granularity = max(q->limits.discard_granularity >> 9, 1U);
- alignment = bdev_discard_alignment(bdev) >> 9;
- alignment = sector_div(alignment, granularity);
+ alignment = (bdev_discard_alignment(bdev) >> 9) % granularity;
/*
* Ensure that max_discard_sectors is of the proper
* granularity, so that requests stay aligned after a split.
*/
max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9);
- sector_div(max_discard_sectors, granularity);
- max_discard_sectors *= granularity;
+ max_discard_sectors -= max_discard_sectors % granularity;
if (unlikely(!max_discard_sectors)) {
/* Avoid infinite loop below. Being cautious never hurts. */
return -EOPNOTSUPP;
_
Patches currently in -mm which might be from geert@xxxxxxxxxxxxxx are
genirq-correct-fuzzy-and-fragile-irq_retval-definition.patch
block-do-not-call-sector_div-with-a-64-bit-divisor.patch
syscallsh-use-gcc-alias-instead-of-assembler-aliases-for-syscalls.patch
scripts-mod-modpostc-handle-non-abs-crc-symbols.patch
kernel-sysc-remove-obsolete-include-linux-kexech.patch
inith-document-the-existence-of-__initconst.patch
init-make-init-failures-more-explicit.patch
linux-next.patch
x86-add-missed-pgtable_pmd_page_ctor-dtor-calls-for-preallocated-pmds.patch
m68k-handle-pgtable_page_ctor-fail.patch
m68k-handle-pgtable_page_ctor-fail-fix.patch
m68k-handle-pgtable_page_ctor-fail-fix-fix.patch
mm-dynamically-allocate-page-ptl-if-it-cannot-be-embedded-to-struct-page.patch
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