[Qemu-devel] [patch 0/5] block migration interaction fixes

[Qemu-devel] [patch 0/5] block migration interaction fixes

[Marcelo Tosatti]

See individual patches for details.

[Qemu-devel] [patch 1/5] block-migration: actually disable dirty tracking on cleanup

[Marcelo Tosatti]

[-- Attachment #1: 00-fix-dirty-log-disable --]
[-- Type: text/plain, Size: 739 bytes --]

Call to set_dirty_tracking() is misplaced.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

Index: qemu/block-migration.c
===================================================================
--- qemu.orig/block-migration.c
+++ qemu/block-migration.c
@@ -528,6 +528,8 @@ static void blk_mig_cleanup(Monitor *mon
     BlkMigDevState *bmds;
     BlkMigBlock *blk;
 
+    set_dirty_tracking(0);
+
     while ((bmds = QSIMPLEQ_FIRST(&block_mig_state.bmds_list)) != NULL) {
         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.bmds_list, entry);
         qemu_free(bmds->aio_bitmap);
@@ -540,8 +542,6 @@ static void blk_mig_cleanup(Monitor *mon
         qemu_free(blk);
     }
 
-    set_dirty_tracking(0);
-
     monitor_printf(mon, "\n");
 }
 

[Qemu-devel] [patch 2/5] blockdev: add refcount to DriveInfo

[Marcelo Tosatti]

[-- Attachment #1: 01-driveinfo-ref --]
[-- Type: text/plain, Size: 2628 bytes --]

The host part of a block device can be deleted with in progress
block migration.

To fix this, add a reference count to DriveInfo, freeing resources
on last reference.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
CC: Markus Armbruster <armbru@redhat.com>

Index: qemu/blockdev.c
===================================================================
--- qemu.orig/blockdev.c
+++ qemu/blockdev.c
@@ -40,7 +40,7 @@ void blockdev_auto_del(BlockDriverState 
     DriveInfo *dinfo = drive_get_by_blockdev(bs);
 
     if (dinfo && dinfo->auto_del) {
-        drive_uninit(dinfo);
+        drive_put_ref(dinfo);
     }
 }
 
@@ -110,7 +110,7 @@ static void bdrv_format_print(void *opaq
     fprintf(stderr, " %s", name);
 }
 
-void drive_uninit(DriveInfo *dinfo)
+static void drive_uninit(DriveInfo *dinfo)
 {
     qemu_opts_del(dinfo->opts);
     bdrv_delete(dinfo->bdrv);
@@ -118,6 +118,19 @@ void drive_uninit(DriveInfo *dinfo)
     qemu_free(dinfo);
 }
 
+void drive_put_ref(DriveInfo *dinfo)
+{
+    assert(dinfo->refcount);
+    if (--dinfo->refcount == 0) {
+        drive_uninit(dinfo);
+    }
+}
+
+void drive_get_ref(DriveInfo *dinfo)
+{
+    dinfo->refcount++;
+}
+
 static int parse_block_error_action(const char *buf, int is_read)
 {
     if (!strcmp(buf, "ignore")) {
@@ -421,6 +434,7 @@ DriveInfo *drive_init(QemuOpts *opts, in
     dinfo->bus = bus_id;
     dinfo->unit = unit_id;
     dinfo->opts = opts;
+    dinfo->refcount = 1;
     if (serial)
         strncpy(dinfo->serial, serial, sizeof(dinfo->serial) - 1);
     QTAILQ_INSERT_TAIL(&drives, dinfo, next);
Index: qemu/blockdev.h
===================================================================
--- qemu.orig/blockdev.h
+++ qemu/blockdev.h
@@ -29,6 +29,7 @@ struct DriveInfo {
     QemuOpts *opts;
     char serial[BLOCK_SERIAL_STRLEN + 1];
     QTAILQ_ENTRY(DriveInfo) next;
+    int refcount;
 };
 
 #define MAX_IDE_DEVS	2
@@ -36,7 +37,8 @@ struct DriveInfo {
 
 DriveInfo *drive_get(BlockInterfaceType type, int bus, int unit);
 int drive_get_max_bus(BlockInterfaceType type);
-void drive_uninit(DriveInfo *dinfo);
+void drive_get_ref(DriveInfo *dinfo);
+void drive_put_ref(DriveInfo *dinfo);
 DriveInfo *drive_get_by_blockdev(BlockDriverState *bs);
 
 QemuOpts *drive_add(const char *file, const char *fmt, ...) GCC_FMT_ATTR(2, 3);
Index: qemu/hw/pci-hotplug.c
===================================================================
--- qemu.orig/hw/pci-hotplug.c
+++ qemu/hw/pci-hotplug.c
@@ -146,7 +146,7 @@ void drive_hot_add(Monitor *mon, const Q
 
 err:
     if (dinfo)
-        drive_uninit(dinfo);
+        drive_put_ref(dinfo);
     return;
 }
 

[Qemu-devel] [patch 3/5] block-migration: add reference to target DriveInfo

[Marcelo Tosatti]

[-- Attachment #1: 02-block-migration-use-drive-ref --]
[-- Type: text/plain, Size: 1196 bytes --]

So that ejection of attached device by guest does not free data
in use by block migration instance.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
CC: Markus Armbruster <armbru@redhat.com>

Index: qemu/block-migration.c
===================================================================
--- qemu.orig/block-migration.c
+++ qemu/block-migration.c
@@ -19,6 +19,7 @@
 #include "monitor.h"
 #include "block-migration.h"
 #include "migration.h"
+#include "blockdev.h"
 #include <assert.h>
 
 #define BLOCK_SIZE (BDRV_SECTORS_PER_DIRTY_CHUNK << BDRV_SECTOR_BITS)
@@ -299,6 +300,7 @@ static void init_blk_migration_it(void *
         bmds->completed_sectors = 0;
         bmds->shared_base = block_mig_state.shared_base;
         alloc_aio_bitmap(bmds);
+        drive_get_ref(drive_get_by_blockdev(bs));
 
         block_mig_state.total_sector_sum += sectors;
 
@@ -532,6 +534,7 @@ static void blk_mig_cleanup(Monitor *mon
 
     while ((bmds = QSIMPLEQ_FIRST(&block_mig_state.bmds_list)) != NULL) {
         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.bmds_list, entry);
+        drive_put_ref(drive_get_by_blockdev(bmds->bs));
         qemu_free(bmds->aio_bitmap);
         qemu_free(bmds);
     }

[Qemu-devel] [patch 4/5] Add flag to indicate external users to block device

[Marcelo Tosatti]

[-- Attachment #1: 03-driveinfo-inuse --]
[-- Type: text/plain, Size: 1673 bytes --]

Certain operations such as drive_del or resize cannot be performed
while external users (eg. block migration) reference the block device.

Add a flag to indicate that.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

Index: qemu/block.c
===================================================================
--- qemu.orig/block.c
+++ qemu/block.c
@@ -2770,6 +2770,17 @@ int64_t bdrv_get_dirty_count(BlockDriver
     return bs->dirty_count;
 }
 
+void bdrv_set_in_use(BlockDriverState *bs, int in_use)
+{
+    assert(bs->in_use != in_use);
+    bs->in_use = in_use;
+}
+
+int bdrv_in_use(BlockDriverState *bs)
+{
+    return bs->in_use;
+}
+
 int bdrv_img_create(const char *filename, const char *fmt,
                     const char *base_filename, const char *base_fmt,
                     char *options, uint64_t img_size, int flags)
Index: qemu/block_int.h
===================================================================
--- qemu.orig/block_int.h
+++ qemu/block_int.h
@@ -199,6 +199,7 @@ struct BlockDriverState {
     char device_name[32];
     unsigned long *dirty_bitmap;
     int64_t dirty_count;
+    int in_use; /* users other than guest access, eg. block migration */
     QTAILQ_ENTRY(BlockDriverState) list;
     void *private;
 };
Index: qemu/block.h
===================================================================
--- qemu.orig/block.h
+++ qemu/block.h
@@ -240,6 +240,8 @@ void bdrv_reset_dirty(BlockDriverState *
                       int nr_sectors);
 int64_t bdrv_get_dirty_count(BlockDriverState *bs);
 
+void bdrv_set_in_use(BlockDriverState *bs, int in_use);
+int bdrv_in_use(BlockDriverState *bs);
 
 typedef enum {
     BLKDBG_L1_UPDATE,

[Qemu-devel] [patch 5/5] block: enable in_use flag

[Marcelo Tosatti]

[-- Attachment #1: 04-driveinfo-use-inuse --]
[-- Type: text/plain, Size: 1880 bytes --]

Set block device in use during block migration, disallow drive_del and
bdrv_truncate for in use devices.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

Index: qemu/blockdev.c
===================================================================
--- qemu.orig/blockdev.c
+++ qemu/blockdev.c
@@ -690,6 +690,10 @@ int do_drive_del(Monitor *mon, const QDi
         qerror_report(QERR_DEVICE_NOT_FOUND, id);
         return -1;
     }
+    if (bdrv_in_use(bs)) {
+        qerror_report(QERR_DEVICE_IN_USE, id);
+        return -1;
+    }
 
     /* quiesce block driver; prevent further io */
     qemu_aio_flush();
Index: qemu/block-migration.c
===================================================================
--- qemu.orig/block-migration.c
+++ qemu/block-migration.c
@@ -301,6 +301,7 @@ static void init_blk_migration_it(void *
         bmds->shared_base = block_mig_state.shared_base;
         alloc_aio_bitmap(bmds);
         drive_get_ref(drive_get_by_blockdev(bs));
+        bdrv_set_in_use(bs, 1);
 
         block_mig_state.total_sector_sum += sectors;
 
@@ -534,6 +535,7 @@ static void blk_mig_cleanup(Monitor *mon
 
     while ((bmds = QSIMPLEQ_FIRST(&block_mig_state.bmds_list)) != NULL) {
         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.bmds_list, entry);
+        bdrv_set_in_use(bmds->bs, 0);
         drive_put_ref(drive_get_by_blockdev(bmds->bs));
         qemu_free(bmds->aio_bitmap);
         qemu_free(bmds);
Index: qemu/block.c
===================================================================
--- qemu.orig/block.c
+++ qemu/block.c
@@ -1132,6 +1132,8 @@ int bdrv_truncate(BlockDriverState *bs, 
         return -ENOTSUP;
     if (bs->read_only)
         return -EACCES;
+    if (bdrv_in_use(bs))
+        return -EBUSY;
     ret = drv->bdrv_truncate(bs, offset);
     if (ret == 0) {
         ret = refresh_total_sectors(bs, offset >> BDRV_SECTOR_BITS);

[Qemu-devel] Re: [patch 0/5] block migration interaction fixes

[Kevin Wolf]

Am 26.01.2011 15:12, schrieb Marcelo Tosatti:
> See individual patches for details.

Thanks, applied all to the block branch.

Kevin