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[Qemu-devel] [PULL 30/42] block: define get_block_status return value
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PULL 30/42] block: define get_block_status return value |
Date: |
Fri, 6 Sep 2013 17:39:01 +0200 |
From: Paolo Bonzini <address@hidden>
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 3-8
are left for future extensions.
The return code is compatible with the old is_allocated API: if a driver
only returns 0 or 1 (aka BDRV_BLOCK_DATA) like is_allocated used to,
clients of is_allocated will not have any change in behavior. Still,
we will return more precise information in the next patches and the
new definition of bdrv_is_allocated is already prepared for this.
Reviewed-by: Eric Blake <address@hidden>
Signed-off-by: Paolo Bonzini <address@hidden>
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
block.c | 10 ++++++++--
include/block/block.h | 26 ++++++++++++++++++++++++++
2 files changed, 34 insertions(+), 2 deletions(-)
diff --git a/block.c b/block.c
index a5bfe74..97406ec 100644
--- a/block.c
+++ b/block.c
@@ -3093,7 +3093,7 @@ 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);
@@ -3143,7 +3143,13 @@ 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);
+ if (ret < 0) {
+ return ret;
+ }
+ 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 0b83321..728ec1a 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;
--
1.8.3.1
- [Qemu-devel] [PULL 09/42] aio / timers: fix build of test/test-aio.c on non-linux platforms, (continued)
- [Qemu-devel] [PULL 09/42] aio / timers: fix build of test/test-aio.c on non-linux platforms, Stefan Hajnoczi, 2013/09/06
- [Qemu-devel] [PULL 11/42] iscsi: use bdrv_new() instead of stack structure, Stefan Hajnoczi, 2013/09/06
- [Qemu-devel] [PULL 12/42] block: implement reference count for BlockDriverState, Stefan Hajnoczi, 2013/09/06
- [Qemu-devel] [PULL 13/42] block: make bdrv_delete() static, Stefan Hajnoczi, 2013/09/06
- [Qemu-devel] [PULL 14/42] migration: omit drive ref as we have bdrv_ref now, Stefan Hajnoczi, 2013/09/06
- [Qemu-devel] [PULL 15/42] xen_disk: simplify blk_disconnect with refcnt, Stefan Hajnoczi, 2013/09/06
- [Qemu-devel] [PULL 27/42] qemu-img: always probe the input image for allocated sectors, Stefan Hajnoczi, 2013/09/06
- [Qemu-devel] [PULL 28/42] block: make bdrv_has_zero_init return false for copy-on-write-images, Stefan Hajnoczi, 2013/09/06
- [Qemu-devel] [PULL 29/42] block: introduce bdrv_get_block_status API, Stefan Hajnoczi, 2013/09/06
- [Qemu-devel] [PULL 31/42] block: return get_block_status data and flags for formats, Stefan Hajnoczi, 2013/09/06
- [Qemu-devel] [PULL 30/42] block: define get_block_status return value,
Stefan Hajnoczi <=
- [Qemu-devel] [PULL 32/42] block: use bdrv_has_zero_init to return BDRV_BLOCK_ZERO, Stefan Hajnoczi, 2013/09/06
- [Qemu-devel] [PULL 33/42] block: return BDRV_BLOCK_ZERO past end of backing file, Stefan Hajnoczi, 2013/09/06
[Qemu-devel] [PULL 34/42] qemu-img: add a "map" subcommand, Stefan Hajnoczi, 2013/09/06