lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

block: Allow devices to indicate whether discarded blocks are zeroed

Browse Source 
The discard ioctl is used by mkfs utilities to clear a block device
prior to putting metadata down.  However, not all devices return zeroed
blocks after a discard.  Some drives return stale data, potentially
containing old superblocks.  It is therefore important to know whether
discarded blocks are properly zeroed.

Both ATA and SCSI drives have configuration bits that indicate whether
zeroes are returned after a discard operation.  Implement a block level
interface that allows this information to be bubbled up the stack and
queried via a new block device ioctl.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Martin K. Petersen
2009-12-03 09:24:48 +01:00
committed by Jens Axboe
parent 464191c65b
commit 98262f2762
6 changed files with 32 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
include/linux/blkdev.h
View File

@ -322,6 +322,7 @@ struct queue_limits {
unsigned char misaligned;
unsigned char discard_misaligned;
unsigned char no_cluster;
signed char discard_zeroes_data;
};
struct request_queue
@ -1150,6 +1151,19 @@ static inline int queue_sector_discard_alignment(struct request_queue *q,
& (q->limits.discard_granularity - 1);
}
static inline unsigned int queue_discard_zeroes_data(struct request_queue *q)
{
if (q->limits.discard_zeroes_data == 1)
return 1;
return 0;
}
static inline unsigned int bdev_discard_zeroes_data(struct block_device *bdev)
{
return queue_discard_zeroes_data(bdev_get_queue(bdev));
}
static inline int queue_dma_alignment(struct request_queue *q)
{
return q ? q->dma_alignment : 511;