diff mbox series

[v6,4/5] block/io: fix bdrv_is_allocated_above

Message ID 20200916122008.20303-5-vsementsov@virtuozzo.com
State New
Headers show
Series fix & merge block_status_above and is_allocated_above | expand

Commit Message

Vladimir Sementsov-Ogievskiy Sept. 16, 2020, 12:20 p.m. UTC 
bdrv_is_allocated_above wrongly handles short backing files: it reports
after-EOF space as UNALLOCATED which is wrong, as on read the data is
generated on the level of short backing file (if all overlays has
unallocated area at that place).

Reusing bdrv_common_block_status_above fixes the issue and unifies code
path.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
---
 block/io.c | 43 +++++--------------------------------------
 1 file changed, 5 insertions(+), 38 deletions(-)

Comments

Alberto Garcia Sept. 24, 2020, 4:21 p.m. UTC | #1 
On Wed 16 Sep 2020 02:20:07 PM CEST, Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> wrote:
> bdrv_is_allocated_above wrongly handles short backing files: it reports
> after-EOF space as UNALLOCATED which is wrong, as on read the data is
> generated on the level of short backing file (if all overlays has
> unallocated area at that place).
>
> Reusing bdrv_common_block_status_above fixes the issue and unifies code
> path.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> Reviewed-by: Eric Blake <eblake@redhat.com>

Reviewed-by: Alberto Garcia <berto@igalia.com>

Berto
diff mbox series

Patch

diff --git a/block/io.c b/block/io.c
index d864d035ac..95b86429ca 100644
--- a/block/io.c
+++ b/block/io.c
@@ -2491,52 +2491,19 @@  int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t offset,
  * at 'offset + *pnum' may return the same allocation status (in other
  * words, the result is not necessarily the maximum possible range);
  * but 'pnum' will only be 0 when end of file is reached.
- *
  */
 int bdrv_is_allocated_above(BlockDriverState *top,
                             BlockDriverState *base,
                             bool include_base, int64_t offset,
                             int64_t bytes, int64_t *pnum)
 {
-    BlockDriverState *intermediate;
-    int ret;
-    int64_t n = bytes;
-
-    assert(base || !include_base);
-
-    intermediate = top;
-    while (include_base || intermediate != base) {
-        int64_t pnum_inter;
-        int64_t size_inter;
-
-        assert(intermediate);
-        ret = bdrv_is_allocated(intermediate, offset, bytes, &pnum_inter);
-        if (ret < 0) {
-            return ret;
-        }
-        if (ret) {
-            *pnum = pnum_inter;
-            return 1;
-        }
-
-        size_inter = bdrv_getlength(intermediate);
-        if (size_inter < 0) {
-            return size_inter;
-        }
-        if (n > pnum_inter &&
-            (intermediate == top || offset + pnum_inter < size_inter)) {
-            n = pnum_inter;
-        }
-
-        if (intermediate == base) {
-            break;
-        }
-
-        intermediate = backing_bs(intermediate);
+    int ret = bdrv_common_block_status_above(top, base, include_base, false,
+                                             offset, bytes, pnum, NULL, NULL);
+    if (ret < 0) {
+        return ret;
     }
 
-    *pnum = n;
-    return 0;
+    return !!(ret & BDRV_BLOCK_ALLOCATED);
 }
 
 int coroutine_fn