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

Message ID 1385456183-24840-4-git-send-email-pl@kamp.de
State New
Headers show

Commit Message

Peter Lieven Nov. 26, 2013, 8:56 a.m. UTC 
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 <pbonzini@redhat.com>
Signed-off-by: Peter Lieven <pl@kamp.de>
---
 block/iscsi.c |    7 +++++++
 1 file changed, 7 insertions(+)
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Patch

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;
 }