OpenE2K/qemu-e2k
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block: Add bdrv_drain_all_{begin,end}()

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bdrv_drain_all() doesn't allow the caller to do anything after all
pending requests have been completed but before block jobs are
resumed.

This patch splits bdrv_drain_all() into _begin() and _end() for that
purpose. It also adds aio_{disable,enable}_external() calls to disable
external clients in the meantime.

An important restriction of this split is that no new block jobs or
BlockDriverStates can be created between the bdrv_drain_all_begin()
and bdrv_drain_all_end() calls. This is not a concern now because
we'll only be using this in bdrv_reopen_multiple(), but it must be
dealt with if we ever have other uses cases in the future.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Alberto Garcia 2016-10-28 10:08:02 +03:00 committed by Kevin Wolf
parent ad0e90a682
commit c0778f6693
2 changed files with 26 additions and 3 deletions
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27
block/io.c
View File

@ -273,8 +273,14 @@ void bdrv_drain(BlockDriverState *bs)
*
* This function does not flush data to disk, use bdrv_flush_all() for that
* after calling this function.
*
* This pauses all block jobs and disables external clients. It must
* be paired with bdrv_drain_all_end().
*
* NOTE: no new block jobs or BlockDriverStates can be created between
* the bdrv_drain_all_begin() and bdrv_drain_all_end() calls.
*/
void bdrv_drain_all(void)
void bdrv_drain_all_begin(void)
{
/* Always run first iteration so any pending completion BHs run */
bool waited = true;
@ -297,6 +303,7 @@ void bdrv_drain_all(void)
aio_context_acquire(aio_context);
bdrv_parent_drained_begin(bs);
bdrv_io_unplugged_begin(bs);
aio_disable_external(aio_context);
aio_context_release(aio_context);
if (!g_slist_find(aio_ctxs, aio_context)) {
@ -326,17 +333,25 @@ void bdrv_drain_all(void)
}
}
g_slist_free(aio_ctxs);
}
void bdrv_drain_all_end(void)
{
BlockDriverState *bs;
BdrvNextIterator it;
BlockJob *job = NULL;
for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
AioContext *aio_context = bdrv_get_aio_context(bs);
aio_context_acquire(aio_context);
aio_enable_external(aio_context);
bdrv_io_unplugged_end(bs);
bdrv_parent_drained_end(bs);
aio_context_release(aio_context);
}
g_slist_free(aio_ctxs);
job = NULL;
while ((job = block_job_next(job))) {
AioContext *aio_context = blk_get_aio_context(job->blk);
@ -346,6 +361,12 @@ void bdrv_drain_all(void)
}
}
void bdrv_drain_all(void)
{
bdrv_drain_all_begin();
bdrv_drain_all_end();
}
/**
* Remove an active request from the tracked requests list
*

2
include/block/block.h
View File

@ -332,6 +332,8 @@ int bdrv_flush_all(void);
void bdrv_close_all(void);
void bdrv_drain(BlockDriverState *bs);
void coroutine_fn bdrv_co_drain(BlockDriverState *bs);
void bdrv_drain_all_begin(void);
void bdrv_drain_all_end(void);
void bdrv_drain_all(void);
#define BDRV_POLL_WHILE(bs, cond) ({ \