From 44ec95425c1d9dce6e4638c29e4362cfb44814e7 Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Tue, 20 Feb 2007 11:01:57 -0500 Subject: [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 --- block/ll_rw_blk.c | 2 ++ block/scsi_ioctl.c | 4 +++- 2 files changed, 5 insertions(+), 1 deletion(-) (limited to 'block') 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) -- cgit v1.2.3-70-g09d2