From 9f251abbe1e79a790aaf3a3ca48de60deb0c2a10 Mon Sep 17 00:00:00 2001

From: John Snow <jsnow@redhat.com>

Date: Wed, 3 Apr 2019 18:18:55 +0200

Subject: [PATCH 150/163] block/dirty-bitmaps: implement inconsistent bit

RH-Author: John Snow <jsnow@redhat.com>

Message-id: <20190403181857.9693-20-jsnow@redhat.com>

Patchwork-id: 85428

O-Subject: [RHEL-7.7 qemu-kvm-rhev PATCH 19/21] block/dirty-bitmaps: implement inconsistent bit

Bugzilla: 1677073

RH-Acked-by: Max Reitz <mreitz@redhat.com>

RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

RH-Acked-by: Sergio Lopez Pascual <slp@redhat.com>

Set the inconsistent bit on load instead of rejecting such bitmaps.

There is no way to un-set it; the only option is to delete the bitmap.

Obvervations:

- bitmap loading does not need to update the header for in_use bitmaps.

- inconsistent bitmaps don't need to have their data loaded; they're

  glorified corruption sentinels.

- bitmap saving does not need to save inconsistent bitmaps back to disk.

- bitmap reopening DOES need to drop the readonly flag from inconsistent

  bitmaps to allow reopening of qcow2 files with non-qemu-owned bitmaps

  being eventually flushed back to disk.

Signed-off-by: John Snow <jsnow@redhat.com>

Reviewed-by: Eric Blake <eblake@redhat.com>

Message-id: 20190301191545.8728-8-jsnow@redhat.com

Signed-off-by: John Snow <jsnow@redhat.com>

(cherry picked from commit 74da6b943565c451d275de1b0253546c5e729d20)

Signed-off-by: John Snow <jsnow@redhat.com>

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 block/qcow2-bitmap.c | 99 +++++++++++++++++++++++++++-------------------------

 1 file changed, 51 insertions(+), 48 deletions(-)

diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c

index 4899719..cbab0e5 100644

--- a/block/qcow2-bitmap.c

+++ b/block/qcow2-bitmap.c

@@ -345,11 +345,17 @@ static BdrvDirtyBitmap *load_bitmap(BlockDriverState *bs,

     uint32_t granularity;

     BdrvDirtyBitmap *bitmap = NULL;

-    if (bm->flags & BME_FLAG_IN_USE) {

-        error_setg(errp, "Bitmap '%s' is in use", bm->name);

+    granularity = 1U << bm->granularity_bits;

+    bitmap = bdrv_create_dirty_bitmap(bs, granularity, bm->name, errp);

+    if (bitmap == NULL) {

         goto fail;

     }

+    if (bm->flags & BME_FLAG_IN_USE) {

+        /* Data is unusable, skip loading it */

+        return bitmap;

+    }

+

     ret = bitmap_table_load(bs, &bm->table, &bitmap_table);

     if (ret < 0) {

         error_setg_errno(errp, -ret,

@@ -358,12 +364,6 @@ static BdrvDirtyBitmap *load_bitmap(BlockDriverState *bs,

         goto fail;

     }

-    granularity = 1U << bm->granularity_bits;

-    bitmap = bdrv_create_dirty_bitmap(bs, granularity, bm->name, errp);

-    if (bitmap == NULL) {

-        goto fail;

-    }

-

     ret = load_bitmap_data(bs, bitmap_table, bm->table.size, bitmap);

     if (ret < 0) {

         error_setg_errno(errp, -ret, "Could not read bitmap '%s' from image",

@@ -951,6 +951,7 @@ bool qcow2_load_dirty_bitmaps(BlockDriverState *bs, Error **errp)

     Qcow2Bitmap *bm;

     GSList *created_dirty_bitmaps = NULL;

     bool header_updated = false;

+    bool needs_update = false;

     if (s->nb_bitmaps == 0) {

         /* No bitmaps - nothing to do */

@@ -964,35 +965,39 @@ bool qcow2_load_dirty_bitmaps(BlockDriverState *bs, Error **errp)

     }

     QSIMPLEQ_FOREACH(bm, bm_list, entry) {

-        if (!(bm->flags & BME_FLAG_IN_USE)) {

-            BdrvDirtyBitmap *bitmap = load_bitmap(bs, bm, errp);

-            if (bitmap == NULL) {

-                goto fail;

-            }

+        BdrvDirtyBitmap *bitmap = load_bitmap(bs, bm, errp);

+        if (bitmap == NULL) {

+            goto fail;

+        }

-            if (!(bm->flags & BME_FLAG_AUTO)) {

-                bdrv_disable_dirty_bitmap(bitmap);

-            }

-            bdrv_dirty_bitmap_set_persistance(bitmap, true);

+        bdrv_dirty_bitmap_set_persistance(bitmap, true);

+        if (bm->flags & BME_FLAG_IN_USE) {

+            bdrv_dirty_bitmap_set_inconsistent(bitmap);

+        } else {

+            /* NB: updated flags only get written if can_write(bs) is true. */

             bm->flags |= BME_FLAG_IN_USE;

-            created_dirty_bitmaps =

-                    g_slist_append(created_dirty_bitmaps, bitmap);

+            needs_update = true;

         }

+        if (!(bm->flags & BME_FLAG_AUTO)) {

+            bdrv_disable_dirty_bitmap(bitmap);

+        }

+        created_dirty_bitmaps =

+            g_slist_append(created_dirty_bitmaps, bitmap);

     }

-    if (created_dirty_bitmaps != NULL) {

-        if (can_write(bs)) {

-            /* in_use flags must be updated */

-            int ret = update_ext_header_and_dir_in_place(bs, bm_list);

-            if (ret < 0) {

-                error_setg_errno(errp, -ret, "Can't update bitmap directory");

-                goto fail;

-            }

-            header_updated = true;

-        } else {

-            g_slist_foreach(created_dirty_bitmaps, set_readonly_helper,

-                            (gpointer)true);

+    if (needs_update && can_write(bs)) {

+        /* in_use flags must be updated */

+        int ret = update_ext_header_and_dir_in_place(bs, bm_list);

+        if (ret < 0) {

+            error_setg_errno(errp, -ret, "Can't update bitmap directory");

+            goto fail;

         }

+        header_updated = true;

+    }

+

+    if (!can_write(bs)) {

+        g_slist_foreach(created_dirty_bitmaps, set_readonly_helper,

+                        (gpointer)true);

     }

     g_slist_free(created_dirty_bitmaps);

@@ -1114,23 +1119,21 @@ int qcow2_reopen_bitmaps_rw_hint(BlockDriverState *bs, bool *header_updated,

     }

     QSIMPLEQ_FOREACH(bm, bm_list, entry) {

-        if (!(bm->flags & BME_FLAG_IN_USE)) {

-            BdrvDirtyBitmap *bitmap = bdrv_find_dirty_bitmap(bs, bm->name);

-            if (bitmap == NULL) {

-                continue;

-            }

-

-            if (!bdrv_dirty_bitmap_readonly(bitmap)) {

-                error_setg(errp, "Bitmap %s is not readonly but not marked"

-                                 "'IN_USE' in the image. Something went wrong,"

-                                 "all the bitmaps may be corrupted", bm->name);

-                ret = -EINVAL;

-                goto out;

-            }

+        BdrvDirtyBitmap *bitmap = bdrv_find_dirty_bitmap(bs, bm->name);

+        if (bitmap == NULL) {

+            continue;

+        }

-            bm->flags |= BME_FLAG_IN_USE;

-            ro_dirty_bitmaps = g_slist_append(ro_dirty_bitmaps, bitmap);

+        if (!bdrv_dirty_bitmap_readonly(bitmap)) {

+            error_setg(errp, "Bitmap %s was loaded prior to rw-reopen, but was "

+                       "not marked as readonly. This is a bug, something went "

+                       "wrong. All of the bitmaps may be corrupted", bm->name);

+            ret = -EINVAL;

+            goto out;

         }

+

+        bm->flags |= BME_FLAG_IN_USE;

+        ro_dirty_bitmaps = g_slist_append(ro_dirty_bitmaps, bitmap);

     }

     if (ro_dirty_bitmaps != NULL) {

@@ -1426,8 +1429,8 @@ void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs, Error **errp)

         Qcow2Bitmap *bm;

         if (!bdrv_dirty_bitmap_get_persistance(bitmap) ||

-            bdrv_dirty_bitmap_readonly(bitmap))

-        {

+            bdrv_dirty_bitmap_readonly(bitmap) ||

+            bdrv_dirty_bitmap_inconsistent(bitmap)) {

             continue;

         }

-- 

1.8.3.1