Commit c0778f66 authored by Alberto Garcia's avatar Alberto Garcia Committed by Kevin Wolf
Browse files

block: Add bdrv_drain_all_{begin,end}() 



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: default avatarAlberto Garcia <berto@igalia.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: default avatarKevin Wolf <kwolf@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent ad0e90a6

block/io.c

+24 −3
Original line number Diff line number Diff line
@@ -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

 *

include/block/block.h

+2 −0
Original line number Diff line number Diff line
@@ -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) ({                       \