On 11/27/2014 05:55 PM, Markus Armbruster wrote:
I'm sorry for the delay. I got the flu and have difficulties thinking
straight for longer than a few minutes.
Ekaterina Tumanova <tuman...@linux.vnet.ibm.com> writes:
Add driver functions for geometry and blocksize detection
Signed-off-by: Ekaterina Tumanova <tuman...@linux.vnet.ibm.com>
---
block.c | 26 ++++++++++++++++++++++++++
include/block/block.h | 20 ++++++++++++++++++++
include/block/block_int.h | 3 +++
3 files changed, 49 insertions(+)
diff --git a/block.c b/block.c
index a612594..5df35cf 100644
--- a/block.c
+++ b/block.c
@@ -548,6 +548,32 @@ void bdrv_refresh_limits(BlockDriverState *bs, Error
**errp)
}
}
+struct ProbeBlockSize bdrv_probe_blocksizes(BlockDriverState *bs)
+{
+ BlockDriver *drv = bs->drv;
+ struct ProbeBlockSize err_geo = { .rc = -1 };
+
+ assert(drv != NULL);
+ if (drv->bdrv_probe_blocksizes) {
+ return drv->bdrv_probe_blocksizes(bs);
+ }
+
+ return err_geo;
+}
I'm not sure about "probe". Naming is hard. "get"?
There was already "bdrv_get_geometry", and I wanted the _geometry and
_blocksize functions to use the same naming convention.
I thought probe might be more suitable, since we do not "get" the value
for sure. maybe "detect"?
Squashing status and actual payload into a single struct to use as
return type isn't wrong, but unusual. When the payload can't represent
failure conveniently, we usually return status, and write the payload to
a buffer provided by the caller, like this:
int bdrv_get_blocksizes(BlockDriverState *bs,
uint16_t *physical_blk_sz,
uint16_t *logical_blk_sz)
Or, with a struct to hold both sizes:
int bdrv_get_blocksizes(BlockDriverState *bs, BlockSizes *bsz)
Do you insist on changing that? Returning a struct via stack seemed
useful to me, since there was less probability of caller allocating
a buffer of incorrect size or smth like that.
Such a struct should ideally be used in other places where we store both
sizes.
A brief function contract comment wouldn't hurt. Something like
/*
* Try to get @bs's logical and physical block size.
* Block sizes are always a multiple of BDRV_SECTOR_SIZE.
* On success, store them in ... and return 0.
* On failure, return -errno.
*/
will do
+
+struct ProbeGeometry bdrv_probe_geometry(BlockDriverState *bs)
+{
+ BlockDriver *drv = bs->drv;
+ struct ProbeGeometry err_geo = { .rc = -1 };
+
+ assert(drv != NULL);
+ if (drv->bdrv_probe_geometry) {
+ return drv->bdrv_probe_geometry(bs);
+ }
+
+ return err_geo;
+}
+
/*
* Create a uniquely-named empty temporary file.
* Return 0 upon success, otherwise a negative errno value.
diff --git a/include/block/block.h b/include/block/block.h
index 5450610..3287dbc 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -60,6 +60,24 @@ typedef enum {
BDRV_REQ_MAY_UNMAP = 0x4,
} BdrvRequestFlags;
+struct ProbeBlockSize {
+ int rc;
+ struct BlockSize {
+ uint16_t phys;
+ uint16_t log;
+ } size;
+};
Use of uint16_t for block sizes is silly, but not your fault, you just
follow existing usage.
+
+struct ProbeGeometry {
+ int rc;
+ struct HDGeometry {
+ uint32_t heads;
+ uint32_t sectors;
+ uint32_t cylinders;
+ uint32_t start;
+ } geo;
+};
+
#define BDRV_O_RDWR 0x0002
#define BDRV_O_SNAPSHOT 0x0008 /* open the file read only and save writes
in a snapshot */
#define BDRV_O_TEMPORARY 0x0010 /* delete the file after use */
@@ -538,6 +556,8 @@ AioContext *bdrv_get_aio_context(BlockDriverState *bs);
* the old #AioContext is not executing.
*/
void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context);
+struct ProbeBlockSize bdrv_probe_blocksizes(BlockDriverState *bs);
+struct ProbeGeometry bdrv_probe_geometry(BlockDriverState *bs);
void bdrv_io_plug(BlockDriverState *bs);
void bdrv_io_unplug(BlockDriverState *bs);
diff --git a/include/block/block_int.h b/include/block/block_int.h
index a1c17b9..830e564 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -271,6 +271,9 @@ struct BlockDriver {
void (*bdrv_io_unplug)(BlockDriverState *bs);
void (*bdrv_flush_io_queue)(BlockDriverState *bs);
+ struct ProbeBlockSize (*bdrv_probe_blocksizes)(BlockDriverState *bs);
+ struct ProbeGeometry (*bdrv_probe_geometry)(BlockDriverState *bs);
+
QLIST_ENTRY(BlockDriver) list;
};
Callbacks need contracts even more than functions do. I know this file
is full of bad examples. Let's not add more :)
Thanks!
Kate.
