block: Move initialisation of BlockLimits to bdrv_refresh_limits()

This function separates filling the BlockLimits from bdrv_open(), which
allows it to call it from other operations which may change the limits
(e.g. modifications to the backing file chain or bdrv_reopen)

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Benoit Canet <benoit@irqsave.net>

1 files changed, 29 insertions, 17 deletions

diff --git a/block/iscsi.c b/block/iscsi.c
index 76b3c96d38..c8bf8dc049 100644
--- a/block/iscsi.c
+++ b/block/iscsi.c
@@ -1265,23 +1265,6 @@ static int iscsi_open(BlockDriverState *bs, QDict *options, int flags,
                sizeof(struct scsi_inquiry_block_limits));
         scsi_free_scsi_task(task);
         task = NULL;
-
-        if (iscsilun->bl.max_unmap < 0xffffffff) {
-            bs->bl.max_discard = sector_lun2qemu(iscsilun->bl.max_unmap,
-                                                 iscsilun);
-        }
-        bs->bl.discard_alignment = sector_lun2qemu(iscsilun->bl.opt_unmap_gran,
-                                                   iscsilun);
-
-        if (iscsilun->bl.max_ws_len < 0xffffffff) {
-            bs->bl.max_write_zeroes = sector_lun2qemu(iscsilun->bl.max_ws_len,
-                                                      iscsilun);
-        }
-        bs->bl.write_zeroes_alignment = sector_lun2qemu(iscsilun->bl.opt_unmap_gran,
-                                                        iscsilun);
-
-        bs->bl.opt_transfer_length = sector_lun2qemu(iscsilun->bl.opt_xfer_len,
-                                                     iscsilun);
     }
 
 #if defined(LIBISCSI_FEATURE_NOP_COUNTER)
@@ -1326,6 +1309,34 @@ static void iscsi_close(BlockDriverState *bs)
     memset(iscsilun, 0, sizeof(IscsiLun));
 }
 
+static int iscsi_refresh_limits(BlockDriverState *bs)
+{
+    IscsiLun *iscsilun = bs->opaque;
+
+    /* We don't actually refresh here, but just return data queried in
+     * iscsi_open(): iscsi targets don't change their limits. */
+    if (iscsilun->lbp.lbpu || iscsilun->lbp.lbpws) {
+        if (iscsilun->bl.max_unmap < 0xffffffff) {
+            bs->bl.max_discard = sector_lun2qemu(iscsilun->bl.max_unmap,
+                                                 iscsilun);
+        }
+        bs->bl.discard_alignment = sector_lun2qemu(iscsilun->bl.opt_unmap_gran,
+                                                   iscsilun);
+
+        if (iscsilun->bl.max_ws_len < 0xffffffff) {
+            bs->bl.max_write_zeroes = sector_lun2qemu(iscsilun->bl.max_ws_len,
+                                                      iscsilun);
+        }
+        bs->bl.write_zeroes_alignment = sector_lun2qemu(iscsilun->bl.opt_unmap_gran,
+                                                        iscsilun);
+
+        bs->bl.opt_transfer_length = sector_lun2qemu(iscsilun->bl.opt_xfer_len,
+                                                     iscsilun);
+    }
+
+    return 0;
+}
+
 static int iscsi_truncate(BlockDriverState *bs, int64_t offset)
 {
     IscsiLun *iscsilun = bs->opaque;
@@ -1438,6 +1449,7 @@ static BlockDriver bdrv_iscsi = {
     .bdrv_getlength  = iscsi_getlength,
     .bdrv_get_info   = iscsi_get_info,
     .bdrv_truncate   = iscsi_truncate,
+    .bdrv_refresh_limits = iscsi_refresh_limits,
 
 #if defined(LIBISCSI_FEATURE_IOVECTOR)
     .bdrv_co_get_block_status = iscsi_co_get_block_status,