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From: Hanna Reitz <hreitz@redhat.com>
To: qemu-block@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>, Hanna Reitz <hreitz@redhat.com>,
	Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
	qemu-devel@nongnu.org
Subject: [PATCH v3 4/6] block/file-posix: Do not force-cap *pnum
Date: Thu, 12 Aug 2021 10:41:46 +0200	[thread overview]
Message-ID: <20210812084148.14458-5-hreitz@redhat.com> (raw)
In-Reply-To: <20210812084148.14458-1-hreitz@redhat.com>

bdrv_co_block_status() does it for us, we do not need to do it here.

The advantage of not capping *pnum is that bdrv_co_block_status() can
cache larger data regions than requested by its caller.

Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
---
 block/file-posix.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/block/file-posix.c b/block/file-posix.c
index cb9bffe047..9f35e5631a 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -2744,7 +2744,8 @@ static int find_allocation(BlockDriverState *bs, off_t start,
  * the specified offset) that are known to be in the same
  * allocated/unallocated state.
  *
- * 'bytes' is the max value 'pnum' should be set to.
+ * 'bytes' is a soft cap for 'pnum'.  If the information is free, 'pnum' may
+ * well exceed it.
  */
 static int coroutine_fn raw_co_block_status(BlockDriverState *bs,
                                             bool want_zero,
@@ -2782,7 +2783,7 @@ static int coroutine_fn raw_co_block_status(BlockDriverState *bs,
     } else if (data == offset) {
         /* On a data extent, compute bytes to the end of the extent,
          * possibly including a partial sector at EOF. */
-        *pnum = MIN(bytes, hole - offset);
+        *pnum = hole - offset;
 
         /*
          * We are not allowed to return partial sectors, though, so
@@ -2801,7 +2802,7 @@ static int coroutine_fn raw_co_block_status(BlockDriverState *bs,
     } else {
         /* On a hole, compute bytes to the beginning of the next extent.  */
         assert(hole == offset);
-        *pnum = MIN(bytes, data - offset);
+        *pnum = data - offset;
         ret = BDRV_BLOCK_ZERO;
     }
     *map = offset;
-- 
2.31.1



  parent reply	other threads:[~2021-08-12  8:45 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-12  8:41 [PATCH v3 0/6] block-status cache for data regions Hanna Reitz
2021-08-12  8:41 ` [PATCH v3 1/6] block: Drop BDS comment regarding bdrv_append() Hanna Reitz
2021-08-12  8:41 ` [PATCH v3 2/6] block: block-status cache for data regions Hanna Reitz
2021-08-16 21:38   ` Eric Blake
2021-08-17  6:19     ` Hanna Reitz
2021-08-25  9:54   ` Vladimir Sementsov-Ogievskiy
2021-08-12  8:41 ` [PATCH v3 3/6] block: Clarify that @bytes is no limit on *pnum Hanna Reitz
2021-08-17 15:03   ` Eric Blake
2021-08-12  8:41 ` Hanna Reitz [this message]
2021-08-12  8:41 ` [PATCH v3 5/6] block/gluster: Do not force-cap *pnum Hanna Reitz
2021-08-12  8:41 ` [PATCH v3 6/6] block/iscsi: " Hanna Reitz
2021-09-07  9:23 ` [PATCH v3 0/6] block-status cache for data regions Hanna Reitz

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