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[SCSI] seperate max_sectors from max_hw_sectors

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- export __blk_put_request and blk_execute_rq_nowait
needed for async REQ_BLOCK_PC requests
- seperate max_hw_sectors and max_sectors for block/scsi_ioctl.c and
SG_IO bio.c helpers per Jens's last comments. Since block/scsi_ioctl.c SG_IO was
already testing against max_sectors and SCSI-ml was setting max_sectors and
max_hw_sectors to the same value this does not change any scsi SG_IO behavior. It only
prepares ll_rw_blk.c, scsi_ioctl.c and bio.c for when SCSI-ml begins to set
a valid max_hw_sectors for all LLDs. Today if a LLD does not set it
SCSI-ml sets it to a safe default and some LLDs set it to a artificial low
value to overcome memory and feedback issues.

Note: Since we now cap max_sectors to BLK_DEF_MAX_SECTORS, which is 1024,
drivers that used to call blk_queue_max_sectors with a large value of
max_sectors will now see the fs requests capped to BLK_DEF_MAX_SECTORS.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
This commit is contained in:
Mike Christie
2005-12-05 02:37:06 -06:00
committed by James Bottomley
parent 8b05b773b6
commit defd94b754
6 changed files with 42 additions and 21 deletions
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3
include/linux/blkdev.h
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@@ -702,7 +702,8 @@ extern int blkdev_issue_flush(struct block_device *, sector_t *);
#define MAX_PHYS_SEGMENTS 128
#define MAX_HW_SEGMENTS 128
#define MAX_SECTORS 255
#define SAFE_MAX_SECTORS 255
#define BLK_DEF_MAX_SECTORS 1024
#define MAX_SEGMENT_SIZE 65536