mirrors/qemu
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

block: add request tracking

Browse Source 
The block layer does not know about pending requests.  This information
is necessary for copy-on-read since overlapping requests must be
serialized to prevent races that corrupt the image.

The BlockDriverState gets a new tracked_request list field which
contains all pending requests.  Each request is a BdrvTrackedRequest
record with sector_num, nb_sectors, and is_write fields.

Note that request tracking is always enabled but hopefully this extra
work is so small that it doesn't justify adding an enable/disable flag.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2011-11-17 13:40:27 +00:00 committed by Kevin Wolf
parent e8ee5e4c47
commit dbffbdcfff
2 changed files with 51 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

48
block.c
View File

@ -1071,6 +1071,42 @@ void bdrv_commit_all(void)
}
}
struct BdrvTrackedRequest {
BlockDriverState *bs;
int64_t sector_num;
int nb_sectors;
bool is_write;
QLIST_ENTRY(BdrvTrackedRequest) list;
};
/**
* Remove an active request from the tracked requests list
*
* This function should be called when a tracked request is completing.
*/
static void tracked_request_end(BdrvTrackedRequest *req)
{
QLIST_REMOVE(req, list);
}
/**
* Add an active request to the tracked requests list
*/
static void tracked_request_begin(BdrvTrackedRequest *req,
BlockDriverState *bs,
int64_t sector_num,
int nb_sectors, bool is_write)
{
*req = (BdrvTrackedRequest){
.bs = bs,
.sector_num = sector_num,
.nb_sectors = nb_sectors,
.is_write = is_write,
};
QLIST_INSERT_HEAD(&bs->tracked_requests, req, list);
}
/*
* Return values:
* 0 - success
@ -1350,6 +1386,8 @@ static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
{
BlockDriver *drv = bs->drv;
BdrvTrackedRequest req;
int ret;
if (!drv) {
return -ENOMEDIUM;
@ -1363,7 +1401,10 @@ static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs,
bdrv_io_limits_intercept(bs, false, nb_sectors);
}
return drv->bdrv_co_readv(bs, sector_num, nb_sectors, qiov);
tracked_request_begin(&req, bs, sector_num, nb_sectors, false);
ret = drv->bdrv_co_readv(bs, sector_num, nb_sectors, qiov);
tracked_request_end(&req);
return ret;
}
int coroutine_fn bdrv_co_readv(BlockDriverState *bs, int64_t sector_num,
@ -1381,6 +1422,7 @@ static int coroutine_fn bdrv_co_do_writev(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
{
BlockDriver *drv = bs->drv;
BdrvTrackedRequest req;
int ret;
if (!bs->drv) {
@ -1398,6 +1440,8 @@ static int coroutine_fn bdrv_co_do_writev(BlockDriverState *bs,
bdrv_io_limits_intercept(bs, true, nb_sectors);
}
tracked_request_begin(&req, bs, sector_num, nb_sectors, true);
ret = drv->bdrv_co_writev(bs, sector_num, nb_sectors, qiov);
if (bs->dirty_bitmap) {
@ -1408,6 +1452,8 @@ static int coroutine_fn bdrv_co_do_writev(BlockDriverState *bs,
bs->wr_highest_sector = sector_num + nb_sectors - 1;
}
tracked_request_end(&req);
return ret;
}

4
block_int.h
View File

@ -51,6 +51,8 @@
#define BLOCK_OPT_PREALLOC "preallocation"
#define BLOCK_OPT_SUBFMT "subformat"
typedef struct BdrvTrackedRequest BdrvTrackedRequest;
typedef struct AIOPool {
void (*cancel)(BlockDriverAIOCB *acb);
int aiocb_size;
@ -255,6 +257,8 @@ struct BlockDriverState {
int in_use; /* users other than guest access, eg. block migration */
QTAILQ_ENTRY(BlockDriverState) list;
void *private;
QLIST_HEAD(, BdrvTrackedRequest) tracked_requests;
};
struct BlockDriverAIOCB {