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block: Fix discard topology stacking and reporting

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In some cases we would end up stacking discard_zeroes_data incorrectly.
Fix this by enabling the feature by default for stacking drivers and
clearing it for low-level drivers. Incorporating a device that does not
support dzd will then cause the feature to be disabled in the stacking
driver.

Also ensure that the maximum discard value does not overflow when
exported in sysfs and return 0 in the alignment and dzd fields for
devices that don't support discard.

Reported-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
This commit is contained in:
Martin K. Petersen
2011-05-18 10:37:35 +02:00
committed by Jens Axboe
parent bbdd304cf6
commit a934a00a69
3 changed files with 9 additions and 4 deletions
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7
include/linux/blkdev.h
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@@ -257,7 +257,7 @@ struct queue_limits {
unsigned char misaligned;
unsigned char discard_misaligned;
unsigned char cluster;
signed char discard_zeroes_data;
unsigned char discard_zeroes_data;
};
struct request_queue
@@ -1069,13 +1069,16 @@ static inline int queue_limit_discard_alignment(struct queue_limits *lim, sector
{
unsigned int alignment = (sector << 9) & (lim->discard_granularity - 1);
if (!lim->max_discard_sectors)
return 0;
return (lim->discard_granularity + lim->discard_alignment - alignment)
& (lim->discard_granularity - 1);
}
static inline unsigned int queue_discard_zeroes_data(struct request_queue *q)
{
if (q->limits.discard_zeroes_data == 1)
if (q->limits.max_discard_sectors && q->limits.discard_zeroes_data == 1)
return 1;
return 0;