[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] [PATCH 01/11] block: switch blk_write_compressed() to b

From: Pavel Butsykin
Subject: Re: [Qemu-devel] [PATCH 01/11] block: switch blk_write_compressed() to byte-based interface
Date: Tue, 28 Jun 2016 14:32:09 +0300
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0

On 28.06.2016 13:53, Kevin Wolf wrote:
Am 13.06.2016 um 16:23 hat Eric Blake geschrieben:
On 05/31/2016 03:15 AM, Denis V. Lunev wrote:
From: Pavel Butsykin <address@hidden>

This is a preparatory patch, which continues the general trend of the transition
to the byte-based interfaces.

Signed-off-by: Pavel Butsykin <address@hidden>
Signed-off-by: Denis V. Lunev <address@hidden>
CC: Jeff Cody <address@hidden>
CC: Markus Armbruster <address@hidden>
CC: Eric Blake <address@hidden>
CC: John Snow <address@hidden>
CC: Stefan Hajnoczi <address@hidden>
CC: Kevin Wolf <address@hidden>

-int bdrv_write_compressed(BlockDriverState *bs, int64_t sector_num,
-                          const uint8_t *buf, int nb_sectors)
+int bdrv_pwrite_compressed(BlockDriverState *bs, int64_t offset,
+                           const void *buf, int count)
      BlockDriver *drv = bs->drv;
      int ret;
@@ -1791,14 +1791,15 @@ int bdrv_write_compressed(BlockDriverState *bs, int64_t 
      if (!drv->bdrv_write_compressed) {
          return -ENOTSUP;
-    ret = bdrv_check_request(bs, sector_num, nb_sectors);
+    ret = bdrv_check_byte_request(bs, offset, count);
      if (ret < 0) {
          return ret;


-    return drv->bdrv_write_compressed(bs, sector_num, buf, nb_sectors);
+    return drv->bdrv_write_compressed(bs, offset >> BDRV_SECTOR_BITS, buf,
+                                      count >> BDRV_SECTOR_BITS);

If you are going to shift right, you need to first assert that offset
and count are aligned (and thus that our call to a sector interface
isn't going to operate on the wrong data).  See for example commit 166fe960.

Yes, I would like to have these assertions at least.

But I'm wondering what the point of converting the interface is when we
don't intend to actually support sub-sector requests and the sector
alignment is still required at the end of the series.

Because at the time of sending patches, the format drivers still had
the sector-based interfaces. In the end, the assertions are not
necessary, because the interface format driver now also byte-based.


reply via email to

[Prev in Thread] Current Thread [Next in Thread]