Commit 44ec9542 authored by Alan Stern's avatar Alan Stern Committed by James Bottomley
Browse files

[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: default avatarAlan Stern <stern@rowland.harvard.edu>
Acked-by: default avatarJens Axboe <jens.axboe@oracle.com>
Acked-by: default avatarDouglas Gilbert <dougg@torque.net>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@SteelEye.com>
parent 1079a2d2

block/ll_rw_blk.c

+2 −0
Original line number Diff line number Diff line
@@ -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

	 */

block/scsi_ioctl.c

+3 −1
Original line number Diff line number Diff line
@@ -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)

drivers/scsi/sg.c

+11 −2
Original line number Diff line number Diff line
@@ -917,6 +917,8 @@ sg_ioctl(struct inode *inode, struct file *filp, 
			return result;

                if (val < 0)

                        return -EINVAL;

		val = min_t(int, val,

				sdp->device->request_queue->max_sectors * 512);

		if (val != sfp->reserve.bufflen) {

			if (sg_res_in_use(sfp) || sfp->mmap_called)

				return -EBUSY;
@@ -925,7 +927,8 @@ sg_ioctl(struct inode *inode, struct file *filp, 
		}

		return 0;

	case SG_GET_RESERVED_SIZE:

		val = (int) sfp->reserve.bufflen;

		val = min_t(int, sfp->reserve.bufflen,

				sdp->device->request_queue->max_sectors * 512);

		return put_user(val, ip);

	case SG_SET_COMMAND_Q:

		result = get_user(val, ip);
@@ -1061,6 +1064,9 @@ sg_ioctl(struct inode *inode, struct file *filp, 
		if (sdp->detached)

			return -ENODEV;

		return scsi_ioctl(sdp->device, cmd_in, p);

	case BLKSECTGET:

		return put_user(sdp->device->request_queue->max_sectors * 512,

				ip);

	default:

		if (read_only)

			return -EPERM;	/* don't know so take safe approach */
@@ -2339,6 +2345,7 @@ sg_add_sfp(Sg_device * sdp, int dev) 
{

	Sg_fd *sfp;

	unsigned long iflags;

	int bufflen;



	sfp = kzalloc(sizeof(*sfp), GFP_ATOMIC | __GFP_NOWARN);

	if (!sfp)
@@ -2369,7 +2376,9 @@ sg_add_sfp(Sg_device * sdp, int dev) 
	if (unlikely(sg_big_buff != def_reserved_size))

		sg_big_buff = def_reserved_size;



	sg_build_reserve(sfp, sg_big_buff);

	bufflen = min_t(int, sg_big_buff,

			sdp->device->request_queue->max_sectors * 512);

	sg_build_reserve(sfp, bufflen);

	SCSI_LOG_TIMEOUT(3, printk("sg_add_sfp:   bufflen=%d, k_use_sg=%d\n",

			   sfp->reserve.bufflen, sfp->reserve.k_use_sg));

	return sfp;

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