[Qemu-devel] [PATCH 3/3] block: get max_transfer limit for char (scsi-generic) devices

[Eric Farman <farman@linux.vnet.ibm.com>]

Commit 6f607174 introduced a routine to get the maximum number
of bytes for a single I/O transfer for block devices, however
scsi generic devices are character devices, not block.  Add
a condition for this, with slightly different logic because
the value is already in bytes, and need not be converted from
blocks as happens for block devices.

Signed-off-by: Eric Farman <farman@linux.vnet.ibm.com>
---
 block/file-posix.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/block/file-posix.c b/block/file-posix.c
index 2115155..c0843c2 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -679,6 +679,13 @@ static void raw_refresh_limits(BlockDriverState *bs, Error **errp)
             if (ret > 0 && ret <= BDRV_REQUEST_MAX_SECTORS) {
                 bs->bl.max_transfer = pow2floor(ret << BDRV_SECTOR_BITS);
             }
+        } else if (S_ISCHR(st.st_mode)) {
+            /* sg returns transfer length in bytes already */
+            int ret = hdev_get_max_transfer_length(bs, s->fd);
+            if (ret > 0 &&
+                (ret >> BDRV_SECTOR_BITS) <= BDRV_REQUEST_MAX_SECTORS) {
+                bs->bl.max_transfer = pow2floor(ret);
+            }
         }
     }
 
-- 
2.8.4