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[Qemu-devel] [PATCH] block: implement bdrv_co_is_allocated() boundary ca
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PATCH] block: implement bdrv_co_is_allocated() boundary cases |
Date: |
Tue, 29 Nov 2011 13:49:51 +0000 |
Cases beyond the end of the disk image are only implemented for block
drivers that do not provide .bdrv_co_is_allocated(). It's worth making
these cases generic so that block drivers that do implement
.bdrv_co_is_allocated() also get them for free.
Suggested-by: Mark Wu <address@hidden>
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
block.c | 26 ++++++++++++++++++--------
1 files changed, 18 insertions(+), 8 deletions(-)
diff --git a/block.c b/block.c
index 4310eb5..1e468a7 100644
--- a/block.c
+++ b/block.c
@@ -2117,23 +2117,33 @@ typedef struct BdrvCoIsAllocatedData {
* not implementing the functionality are assumed to not support backing files,
* hence all their sectors are reported as allocated.
*
+ * If 'sector_num' is beyond the end of the disk image the return value is 0
+ * and 'pnum' is set to 0.
+ *
* 'pnum' is set to the number of sectors (including and immediately following
* the specified sector) that are known to be in the same
* allocated/unallocated state.
*
- * 'nb_sectors' is the max value 'pnum' should be set to.
+ * 'nb_sectors' is the max value 'pnum' should be set to. If nb_sectors goes
+ * beyond the end of the disk image it will be clamped.
*/
int coroutine_fn bdrv_co_is_allocated(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, int *pnum)
{
+ int64_t n;
+
+ if (sector_num >= bs->total_sectors) {
+ *pnum = 0;
+ return 0;
+ }
+
+ n = bs->total_sectors - sector_num;
+ if (n < nb_sectors) {
+ nb_sectors = n;
+ }
+
if (!bs->drv->bdrv_co_is_allocated) {
- int64_t n;
- if (sector_num >= bs->total_sectors) {
- *pnum = 0;
- return 0;
- }
- n = bs->total_sectors - sector_num;
- *pnum = (n < nb_sectors) ? (n) : (nb_sectors);
+ *pnum = nb_sectors;
return 1;
}
--
1.7.7.3
- [Qemu-devel] [PATCH] block: implement bdrv_co_is_allocated() boundary cases,
Stefan Hajnoczi <=