Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=44ec95425c1d9dce6e4638c29e4362cfb44814e7
Commit:     44ec95425c1d9dce6e4638c29e4362cfb44814e7
Parent:     1079a2d251f24a7d9e7576217f5f738bc4218337
Author:     Alan Stern <[EMAIL PROTECTED]>
AuthorDate: Tue Feb 20 11:01:57 2007 -0500
Committer:  James Bottomley <[EMAIL PROTECTED]>
CommitDate: Tue Apr 17 18:09:56 2007 -0400

    [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 <[EMAIL PROTECTED]>
    Acked-by: Jens Axboe <[EMAIL PROTECTED]>
    Acked-by: Douglas Gilbert <[EMAIL PROTECTED]>
    Signed-off-by: James Bottomley <[EMAIL PROTECTED]>
---
 block/ll_rw_blk.c  |    2 ++
 block/scsi_ioctl.c |    4 +++-
 drivers/scsi/sg.c  |   13 +++++++++++--
 3 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index 38c293b..cf8752a 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 65c6a3c..e83f1db 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)
diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 81e3bc7..570977c 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -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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