[2/2] mirror: fix improperly filled copy_bitmap for mirror block job
diff mbox

Message ID 1473424308-19812-3-git-send-email-den@openvz.org
State New
Headers show

Commit Message

Denis V. Lunev Sept. 9, 2016, 12:31 p.m. UTC
bdrv_is_allocated_above() returns true in the case even for completel
zeroed areas as BDRV_BLOCK_ALLOCATED flag is set in both cases.

The patch stops using bdrv_is_allocated_above() wrapper and switches to
bdrv_get_block_status_above() to distinguish zeroed areas and areas with
data to avoid extra IO operations if possible.

Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Stefan Hajnoczi <stefanha@redhat.com>
CC: Fam Zheng <famz@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
CC: Max Reitz <mreitz@redhat.com>
CC: Jeff Cody <jcody@redhat.com>
---
 block/mirror.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

Comments

Eric Blake Sept. 12, 2016, 9:46 p.m. UTC | #1
On 09/09/2016 07:31 AM, Denis V. Lunev wrote:
> bdrv_is_allocated_above() returns true in the case even for completel

s/completel/completely/

> zeroed areas as BDRV_BLOCK_ALLOCATED flag is set in both cases.
> 
> The patch stops using bdrv_is_allocated_above() wrapper and switches to
> bdrv_get_block_status_above() to distinguish zeroed areas and areas with
> data to avoid extra IO operations if possible.
> 
> Signed-off-by: Denis V. Lunev <den@openvz.org>
> CC: Stefan Hajnoczi <stefanha@redhat.com>
> CC: Fam Zheng <famz@redhat.com>
> CC: Kevin Wolf <kwolf@redhat.com>
> CC: Max Reitz <mreitz@redhat.com>
> CC: Jeff Cody <jcody@redhat.com>
> ---
>  block/mirror.c | 18 ++++++++++++------
>  1 file changed, 12 insertions(+), 6 deletions(-)
> 

> @@ -597,13 +602,14 @@ static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s)
>              return 0;
>          }
>  
> -        ret = bdrv_is_allocated_above(bs, base, sector_num, nb_sectors, &n);
> -        if (ret < 0) {
> -            return ret;
> +        status = bdrv_get_block_status_above(bs, base, sector_num,
> +                                             nb_sectors, &n, &file);

Eventually, we should probably fix bdrv_get_block_status_above() to be
byte-based, but that's not a problem with this patch.

Looks okay to me, but I haven't thought closely enough about potential
corner cases to feel comfortable with giving R-b yet...
Jeff Cody Sept. 13, 2016, 5:03 a.m. UTC | #2
On Fri, Sep 09, 2016 at 03:31:48PM +0300, Denis V. Lunev wrote:
> bdrv_is_allocated_above() returns true in the case even for completel
> zeroed areas as BDRV_BLOCK_ALLOCATED flag is set in both cases.
> 
> The patch stops using bdrv_is_allocated_above() wrapper and switches to
> bdrv_get_block_status_above() to distinguish zeroed areas and areas with
> data to avoid extra IO operations if possible.
> 
> Signed-off-by: Denis V. Lunev <den@openvz.org>
> CC: Stefan Hajnoczi <stefanha@redhat.com>
> CC: Fam Zheng <famz@redhat.com>
> CC: Kevin Wolf <kwolf@redhat.com>
> CC: Max Reitz <mreitz@redhat.com>
> CC: Jeff Cody <jcody@redhat.com>
> ---
>  block/mirror.c | 18 ++++++++++++------
>  1 file changed, 12 insertions(+), 6 deletions(-)
> 
> diff --git a/block/mirror.c b/block/mirror.c
> index e0b3f41..da55375 100644
> --- a/block/mirror.c
> +++ b/block/mirror.c
> @@ -548,14 +548,15 @@ static void mirror_throttle(MirrorBlockJob *s)
>  
>  static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s)
>  {
> -    int64_t sector_num, end;
> +    int64_t sector_num, end, alloc_mask;
>      BlockDriverState *base = s->base;
>      BlockDriverState *bs = blk_bs(s->common.blk);
>      BlockDriverState *target_bs = blk_bs(s->target);
> -    int ret, n;
> +    int n;
>  
>      end = s->bdev_length / BDRV_SECTOR_SIZE;
>  
> +    alloc_mask = BDRV_BLOCK_ALLOCATED;
>      if (base == NULL && !bdrv_has_zero_init(target_bs)) {
>          if (!bdrv_can_write_zeroes_with_unmap(target_bs)) {
>              bdrv_set_dirty_bitmap(s->dirty_bitmap, 0, end);
> @@ -583,6 +584,8 @@ static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s)
>          }
>  
>          mirror_drain(s);
> +
> +        alloc_mask = BDRV_BLOCK_DATA;

What about when base == NULL, and bdrv_has_zero_init(target_bs) == true?  In
that case we also know the target image is zeroed, but this does not take
advantage of that.

>      }
>  
>      /* First part, loop on the sectors and initialize the dirty bitmap.  */
> @@ -590,6 +593,8 @@ static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s)
>          /* Just to make sure we are not exceeding int limit. */
>          int nb_sectors = MIN(INT_MAX >> BDRV_SECTOR_BITS,
>                               end - sector_num);
> +        int64_t status;
> +        BlockDriverState *file;
>  
>          mirror_throttle(s);
>  
> @@ -597,13 +602,14 @@ static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s)
>              return 0;
>          }
>  
> -        ret = bdrv_is_allocated_above(bs, base, sector_num, nb_sectors, &n);
> -        if (ret < 0) {
> -            return ret;
> +        status = bdrv_get_block_status_above(bs, base, sector_num,
> +                                             nb_sectors, &n, &file);
> +        if (status < 0) {
> +            return status;

>          }
>  
>          assert(n > 0);
> -        if (ret == 1) {
> +        if (status & alloc_mask) {
>              bdrv_set_dirty_bitmap(s->dirty_bitmap, sector_num, n);
>          }
>          sector_num += n;

-Jeff

Patch
diff mbox

diff --git a/block/mirror.c b/block/mirror.c
index e0b3f41..da55375 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -548,14 +548,15 @@  static void mirror_throttle(MirrorBlockJob *s)
 
 static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s)
 {
-    int64_t sector_num, end;
+    int64_t sector_num, end, alloc_mask;
     BlockDriverState *base = s->base;
     BlockDriverState *bs = blk_bs(s->common.blk);
     BlockDriverState *target_bs = blk_bs(s->target);
-    int ret, n;
+    int n;
 
     end = s->bdev_length / BDRV_SECTOR_SIZE;
 
+    alloc_mask = BDRV_BLOCK_ALLOCATED;
     if (base == NULL && !bdrv_has_zero_init(target_bs)) {
         if (!bdrv_can_write_zeroes_with_unmap(target_bs)) {
             bdrv_set_dirty_bitmap(s->dirty_bitmap, 0, end);
@@ -583,6 +584,8 @@  static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s)
         }
 
         mirror_drain(s);
+
+        alloc_mask = BDRV_BLOCK_DATA;
     }
 
     /* First part, loop on the sectors and initialize the dirty bitmap.  */
@@ -590,6 +593,8 @@  static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s)
         /* Just to make sure we are not exceeding int limit. */
         int nb_sectors = MIN(INT_MAX >> BDRV_SECTOR_BITS,
                              end - sector_num);
+        int64_t status;
+        BlockDriverState *file;
 
         mirror_throttle(s);
 
@@ -597,13 +602,14 @@  static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s)
             return 0;
         }
 
-        ret = bdrv_is_allocated_above(bs, base, sector_num, nb_sectors, &n);
-        if (ret < 0) {
-            return ret;
+        status = bdrv_get_block_status_above(bs, base, sector_num,
+                                             nb_sectors, &n, &file);
+        if (status < 0) {
+            return status;
         }
 
         assert(n > 0);
-        if (ret == 1) {
+        if (status & alloc_mask) {
             bdrv_set_dirty_bitmap(s->dirty_bitmap, sector_num, n);
         }
         sector_num += n;