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block: handle -EBUSY in bdrv_commit_all()

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Monitor operations that manipulate image files must not execute while a
background job (like image streaming) is in progress.  This prevents
corruptions from happening when two pieces of code are manipulating the
image file without knowledge of each other.

The monitor "commit" command raises QERR_DEVICE_IN_USE when
bdrv_commit() returns -EBUSY but "commit all" has no error handling.
This is easy to fix, although note that we do not deliver a detailed
error about which device was busy in the "commit all" case.

Suggested-by: Kevin Wolf <kwolf@redhat.com>
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 2012-03-05 18:10:11 +00:00 committed by Kevin Wolf
parent 3cce16f44d
commit e88774971c
3 changed files with 13 additions and 6 deletions
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8
block.c
View File

@ -1244,13 +1244,17 @@ ro_cleanup:
return ret;
}
void bdrv_commit_all(void)
int bdrv_commit_all(void)
{
BlockDriverState *bs;
QTAILQ_FOREACH(bs, &bdrv_states, list) {
bdrv_commit(bs);
int ret = bdrv_commit(bs);
if (ret < 0) {
return ret;
}
}
return 0;
}
struct BdrvTrackedRequest {

2
block.h
View File

@ -165,7 +165,7 @@ int64_t bdrv_get_allocated_file_size(BlockDriverState *bs);
void bdrv_get_geometry(BlockDriverState *bs, uint64_t *nb_sectors_ptr);
void bdrv_guess_geometry(BlockDriverState *bs, int *pcyls, int *pheads, int *psecs);
int bdrv_commit(BlockDriverState *bs);
void bdrv_commit_all(void);
int bdrv_commit_all(void);
int bdrv_change_backing_file(BlockDriverState *bs,
const char *backing_file, const char *backing_fmt);
void bdrv_register(BlockDriver *bdrv);

9
blockdev.c
View File

@ -627,12 +627,15 @@ void do_commit(Monitor *mon, const QDict *qdict)
{
const char *device = qdict_get_str(qdict, "device");
BlockDriverState *bs;
int ret;
if (!strcmp(device, "all")) {
bdrv_commit_all();
ret = bdrv_commit_all();
if (ret == -EBUSY) {
qerror_report(QERR_DEVICE_IN_USE, device);
return;
}
} else {
int ret;
bs = bdrv_find(device);
if (!bs) {
qerror_report(QERR_DEVICE_NOT_FOUND, device);