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Re: [Qemu-devel] bogus bdrv_check_request in bdrv_co_discard
From: |
Olaf Hering |
Subject: |
Re: [Qemu-devel] bogus bdrv_check_request in bdrv_co_discard |
Date: |
Wed, 16 Mar 2016 11:18:40 +0100 |
User-agent: |
Mutt/1.5.24 (6572) |
On Wed, Mar 09, Olaf Hering wrote:
> On Wed, Mar 09, Kevin Wolf wrote:
>
> > Removing integer overflow checks without removing the potentially
> > overflowing operation doesn't feel like a particularly good idea,
> > though.
>
> Why does the code use signed ints anyway for sectors and offset?!
Until this underlying bug is fixed a change like this works for me:
diff --git a/block/io.c b/block/io.c
index a69bfc4..df1e383 100644
--- a/block/io.c
+++ b/block/io.c
@@ -2464,7 +2464,7 @@ static void coroutine_fn bdrv_discard_co_entry(void
*opaque)
rwco->ret = bdrv_co_discard(rwco->bs, rwco->sector_num, rwco->nb_sectors);
}
-int coroutine_fn bdrv_co_discard(BlockDriverState *bs, int64_t sector_num,
+static int __bdrv_co_discard(BlockDriverState *bs, int64_t sector_num,
int nb_sectors)
{
BdrvTrackedRequest req;
@@ -2546,6 +2546,26 @@ out:
return ret;
}
+int coroutine_fn bdrv_co_discard(BlockDriverState *bs, int64_t sector_num,
+ int nb_sectors)
+{
+ int num, ret;
+ int limit = BDRV_REQUEST_MAX_SECTORS;
+ int remaining = nb_sectors;
+ int64_t sector_offset = sector_num;
+
+ do {
+ num = remaining > limit ? limit : remaining;
+ ret = __bdrv_co_discard(bs, sector_offset, num);
+ if (ret < 0)
+ break;
+ remaining -= num;
+ sector_offset += num;
+ } while (remaining > 0);
+
+ return ret;
+}
+
int bdrv_discard(BlockDriverState *bs, int64_t sector_num, int nb_sectors)
{
Coroutine *co;
Olaf