On 16.07.2013 18:29, Paolo Bonzini wrote:
Define the return value of get_block_status. Bits 0, 1, 2 and 9-62
are valid; bit 63 (the sign bit) is reserved for errors. Bits 3-7
are left for future extensions.
The return code is compatible with the old is_allocated API: returning
just 0 or 1 (aka BDRV_BLOCK_DATA) will not cause any behavioral change
in clients of is_allocated. We will return more precise information
in the next patches.
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
v1->v2: improved comment
block.c | 7 +++++--
include/block/block.h | 26 ++++++++++++++++++++++++++
2 files changed, 31 insertions(+), 2 deletions(-)
diff --git a/block.c b/block.c
index 6e7a8a3..7ff0716 100644
--- a/block.c
+++ b/block.c
@@ -2990,7 +2990,7 @@ static int64_t coroutine_fn
bdrv_co_get_block_status(BlockDriverState *bs,
if (!bs->drv->bdrv_co_get_block_status) {
*pnum = nb_sectors;
- return 1;
+ return BDRV_BLOCK_DATA;
}
return bs->drv->bdrv_co_get_block_status(bs, sector_num, nb_sectors, pnum);
@@ -3040,7 +3040,10 @@ int64_t bdrv_get_block_status(BlockDriverState *bs,
int64_t sector_num,
int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, int *pnum)
{
- return bdrv_get_block_status(bs, sector_num, nb_sectors, pnum);
+ int64_t ret = bdrv_get_block_status(bs, sector_num, nb_sectors, pnum);
just stumbled about a question i have:
isn't here a
if (ret < 0) {
*pnum = 0;
return 0;
}
missing?
I was told that this is the expected return behaviour in the
error case of the old API.
Peter
+ return
+ (ret & BDRV_BLOCK_DATA) ||
+ ((ret & BDRV_BLOCK_ZERO) && !bdrv_has_zero_init(bs));
}
/*
diff --git a/include/block/block.h b/include/block/block.h
index fbc0822..83c7112 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -81,6 +81,32 @@ typedef struct BlockDevOps {
#define BDRV_SECTOR_SIZE (1ULL << BDRV_SECTOR_BITS)
#define BDRV_SECTOR_MASK ~(BDRV_SECTOR_SIZE - 1)
+/* BDRV_BLOCK_DATA: data is read from bs->file or another file
+ * BDRV_BLOCK_ZERO: sectors read as zero
+ * BDRV_BLOCK_OFFSET_VALID: sector stored in bs->file as raw data
+ *
+ * If BDRV_BLOCK_OFFSET_VALID is set, bits 9-62 represent the offset in
+ * bs->file where sector data can be read from as raw data.
+ *
+ * DATA == 0 && ZERO == 0 means that data is read from backing_hd if present.
+ *
+ * DATA ZERO OFFSET_VALID
+ * t t t sectors read as zero, bs->file is zero at offset
+ * t f t sectors read as valid from bs->file at offset
+ * f t t sectors preallocated, read as zero, bs->file not
+ * necessarily zero at offset
+ * f f t sectors preallocated but read from backing_hd,
+ * bs->file contains garbage at offset
+ * t t f sectors preallocated, read as zero, unknown offset
+ * t f f sectors read from unknown file or offset
+ * f t f not allocated or unknown offset, read as zero
+ * f f f not allocated or unknown offset, read from backing_hd
+ */
+#define BDRV_BLOCK_DATA 1
+#define BDRV_BLOCK_ZERO 2
+#define BDRV_BLOCK_OFFSET_VALID 4
+#define BDRV_BLOCK_OFFSET_MASK BDRV_SECTOR_MASK
+
typedef enum {
BDRV_ACTION_REPORT, BDRV_ACTION_IGNORE, BDRV_ACTION_STOP
} BlockErrorAction;
--
Mit freundlichen Grüßen
Peter Lieven
...........................................................
KAMP Netzwerkdienste GmbH
Vestische Str. 89-91 | 46117 Oberhausen
Tel: +49 (0) 208.89 402-50 | Fax: +49 (0) 208.89 402-40
p...@kamp.de | http://www.kamp.de
Geschäftsführer: Heiner Lante | Michael Lante
Amtsgericht Duisburg | HRB Nr. 12154
USt-Id-Nr.: DE 120607556
...........................................................
