path: root/block
diff options
authorAlan Stern <>2007-02-20 11:01:57 -0500
committerJames Bottomley <>2007-04-17 18:09:56 -0400
commit44ec95425c1d9dce6e4638c29e4362cfb44814e7 (patch)
tree6af593dc23a2f7cdb9a0d3ecc46d37aae640c0d8 /block
parent1079a2d251f24a7d9e7576217f5f738bc4218337 (diff)
[SCSI] sg: cap reserved_size values at max_sectors
This patch (as857) modifies the SG_GET_RESERVED_SIZE and SG_SET_RESERVED_SIZE ioctls in the sg driver, capping the values at the device's request_queue's max_sectors value. This will permit cdrecord to obtain a legal value for the maximum transfer length, fixing Bugzilla #7026. The patch also caps the initial reserved_size value. There's no reason to have a reserved buffer larger than max_sectors, since it would be impossible to use the extra space. The corresponding ioctls in the block layer are modified similarly, and the initial value for the reserved_size is set as large as possible. This will effectively make it default to max_sectors. Note that the actual value is meaningless anyway, since block devices don't have a reserved buffer. Finally, the BLKSECTGET ioctl is added to sg, so that there will be a uniform way for users to determine the actual max_sectors value for any raw SCSI transport. Signed-off-by: Alan Stern <> Acked-by: Jens Axboe <> Acked-by: Douglas Gilbert <> Signed-off-by: James Bottomley <>
Diffstat (limited to 'block')
2 files changed, 5 insertions, 1 deletions
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index 38c293b987b..cf8752abd61 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -1925,6 +1925,8 @@ blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS);
blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS);
+ q->sg_reserved_size = INT_MAX;
* all done
diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c
index 65c6a3cba6d..e83f1dbf7c2 100644
--- a/block/scsi_ioctl.c
+++ b/block/scsi_ioctl.c
@@ -78,7 +78,9 @@ static int sg_set_timeout(request_queue_t *q, int __user *p)
static int sg_get_reserved_size(request_queue_t *q, int __user *p)
- return put_user(q->sg_reserved_size, p);
+ unsigned val = min(q->sg_reserved_size, q->max_sectors << 9);
+ return put_user(val, p);
static int sg_set_reserved_size(request_queue_t *q, int __user *p)