[Qemu-devel] [PATCHv2 1.8 3/9] block/iscsi: set bdi->cluster_size

[Peter Lieven]

this patch aims to set bdi->cluster_size to the internal page size
of the iscsi target so that enabled callers can align requests
properly.

Reviewed-by: Paolo Bonzini <address@hidden>
Signed-off-by: Peter Lieven <address@hidden>
---
 block/iscsi.c |    7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/block/iscsi.c b/block/iscsi.c
index 93fee6d..75d6b87 100644
--- a/block/iscsi.c
+++ b/block/iscsi.c
@@ -1580,6 +1580,13 @@ static int iscsi_get_info(BlockDriverState *bs, 
BlockDriverInfo *bdi)
     IscsiLun *iscsilun = bs->opaque;
     bdi->unallocated_blocks_are_zero = !!iscsilun->lbprz;
     bdi->can_write_zeroes_with_unmap = iscsilun->lbprz && iscsilun->lbp.lbpws;
+    /* Guess the internal cluster (page) size of the iscsi target by the means
+     * of opt_unmap_gran. Transfer the unmap granularity only if it has a
+     * reasonable size for bdi->cluster_size */
+    if (iscsilun->bl.opt_unmap_gran * iscsilun->block_size >= 64 * 1024 &&
+        iscsilun->bl.opt_unmap_gran * iscsilun->block_size <= 16 * 1024 * 
1024) {
+        bdi->cluster_size = iscsilun->bl.opt_unmap_gran * iscsilun->block_size;
+    }
     return 0;
 }
 
-- 
1.7.9.5