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>

block.c

@@ -483,6 +483,19 @@ int bdrv_create_file(const char* filename, QEMUOptionParameter *options,
     return ret;
 }
 
+static int bdrv_refresh_limits(BlockDriverState *bs)
+{
+    BlockDriver *drv = bs->drv;
+
+    memset(&bs->bl, 0, sizeof(bs->bl));
+
+    if (drv && drv->bdrv_refresh_limits) {
+        return drv->bdrv_refresh_limits(bs);
+    }
+
+    return 0;
+}
+
 /*
  * Create a uniquely-named empty temporary file.
  * Return 0 upon success, otherwise a negative errno value.
@@ -872,6 +885,8 @@ static int bdrv_open_common(BlockDriverState *bs, BlockDriverState *file,
         goto free_and_fail;
     }
 
+    bdrv_refresh_limits(bs);
+
 #ifndef _WIN32
     if (bs->is_temporary) {
         assert(bs->filename[0] != '\0');
@@ -1085,6 +1100,9 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp)
                 bs->backing_hd->file->filename);
     }
 
+    /* Recalculate the BlockLimits with the backing file */
+    bdrv_refresh_limits(bs);
+
     return 0;
 }
 

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,

block/qcow2.c

@@ -718,7 +718,6 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
     }
 
     qemu_opts_del(opts);
-    bs->bl.write_zeroes_alignment = s->cluster_sectors;
 
     if (s->use_lazy_refcounts && s->qcow_version < 3) {
         error_setg(errp, "Lazy refcounts require a qcow2 image with at least "
@@ -751,6 +750,15 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
     return ret;
 }
 
+static int qcow2_refresh_limits(BlockDriverState *bs)
+{
+    BDRVQcowState *s = bs->opaque;
+
+    bs->bl.write_zeroes_alignment = s->cluster_sectors;
+
+    return 0;
+}
+
 static int qcow2_set_key(BlockDriverState *bs, const char *key)
 {
     BDRVQcowState *s = bs->opaque;
@@ -2268,6 +2276,7 @@ static BlockDriver bdrv_qcow2 = {
 
     .bdrv_change_backing_file   = qcow2_change_backing_file,
 
+    .bdrv_refresh_limits        = qcow2_refresh_limits,
     .bdrv_invalidate_cache      = qcow2_invalidate_cache,
 
     .create_options = qcow2_create_options,

block/qed.c

@@ -495,7 +495,6 @@ static int bdrv_qed_open(BlockDriverState *bs, QDict *options, int flags,
         }
     }
 
-    bs->bl.write_zeroes_alignment = s->header.cluster_size >> BDRV_SECTOR_BITS;
     s->need_check_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL,
                                             qed_need_check_timer_cb, s);
 
@@ -507,6 +506,15 @@ out:
     return ret;
 }
 
+static int bdrv_qed_refresh_limits(BlockDriverState *bs)
+{
+    BDRVQEDState *s = bs->opaque;
+
+    bs->bl.write_zeroes_alignment = s->header.cluster_size >> BDRV_SECTOR_BITS;
+
+    return 0;
+}
+
 /* We have nothing to do for QED reopen, stubs just return
  * success */
 static int bdrv_qed_reopen_prepare(BDRVReopenState *state,
@@ -1616,6 +1624,7 @@ static BlockDriver bdrv_qed = {
     .bdrv_truncate            = bdrv_qed_truncate,
     .bdrv_getlength           = bdrv_qed_getlength,
     .bdrv_get_info            = bdrv_qed_get_info,
+    .bdrv_refresh_limits      = bdrv_qed_refresh_limits,
     .bdrv_change_backing_file = bdrv_qed_change_backing_file,
     .bdrv_invalidate_cache    = bdrv_qed_invalidate_cache,
     .bdrv_check               = bdrv_qed_check,

block/vmdk.c

@@ -428,10 +428,6 @@ static int vmdk_add_extent(BlockDriverState *bs,
     extent->l2_size = l2_size;
     extent->cluster_sectors = flat ? sectors : cluster_sectors;
 
-    if (!flat) {
-        bs->bl.write_zeroes_alignment =
-            MAX(bs->bl.write_zeroes_alignment, cluster_sectors);
-    }
     if (s->num_extents > 1) {
         extent->end_sector = (*(extent - 1)).end_sector + extent->sectors;
     } else {
@@ -902,6 +898,23 @@ fail:
     return ret;
 }
 
+
+static int vmdk_refresh_limits(BlockDriverState *bs)
+{
+    BDRVVmdkState *s = bs->opaque;
+    int i;
+
+    for (i = 0; i < s->num_extents; i++) {
+        if (!s->extents[i].flat) {
+            bs->bl.write_zeroes_alignment =
+                MAX(bs->bl.write_zeroes_alignment,
+                    s->extents[i].cluster_sectors);
+        }
+    }
+
+    return 0;
+}
+
 static int get_whole_cluster(BlockDriverState *bs,
                 VmdkExtent *extent,
                 uint64_t cluster_offset,
@@ -2013,6 +2026,7 @@ static BlockDriver bdrv_vmdk = {
     .bdrv_get_allocated_file_size = vmdk_get_allocated_file_size,
     .bdrv_has_zero_init           = vmdk_has_zero_init,
     .bdrv_get_specific_info       = vmdk_get_specific_info,
+    .bdrv_refresh_limits          = vmdk_refresh_limits,
 
     .create_options               = vmdk_create_options,
 };

include/block/block_int.h

@@ -232,6 +232,8 @@ struct BlockDriver {
     int (*bdrv_debug_resume)(BlockDriverState *bs, const char *tag);
     bool (*bdrv_debug_is_suspended)(BlockDriverState *bs, const char *tag);
 
+    int (*bdrv_refresh_limits)(BlockDriverState *bs);
+
     /*
      * Returns 1 if newly created images are guaranteed to contain only
      * zeros, 0 otherwise.