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block: Add blk_remove_all_bs() 

When bdrv_close_all() is called, instead of force-closing all root
BlockDriverStates, it is better to just drop the reference from all
BlockBackends and let them be closed automatically. This prevents BDS
from getting closed that are still referenced by other BDS, which may
result in loss of cached data.

This patch adds a function for doing that, but does not yet incorporate
it in bdrv_close_all().

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Max Reitz 2016-01-29 16:36:13 +01:00
parent 9c4218e957
commit d8da3cef3b
2 changed files with 16 additions and 0 deletions
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15
block/block-backend.c
View File

@ -223,6 +223,21 @@ void blk_unref(BlockBackend *blk)
}
}
void blk_remove_all_bs(void)
{
BlockBackend *blk;
QTAILQ_FOREACH(blk, &blk_backends, link) {
AioContext *ctx = blk_get_aio_context(blk);
aio_context_acquire(ctx);
if (blk->bs) {
blk_remove_bs(blk);
}
aio_context_release(ctx);
}
}
/*
* Return the BlockBackend after @blk.
* If @blk is null, return the first one.

1
include/sysemu/block-backend.h
View File

@ -68,6 +68,7 @@ BlockBackend *blk_new_open(const char *name, const char *filename,
int blk_get_refcnt(BlockBackend *blk);
void blk_ref(BlockBackend *blk);
void blk_unref(BlockBackend *blk);
void blk_remove_all_bs(void);
const char *blk_name(BlockBackend *blk);
BlockBackend *blk_by_name(const char *name);
BlockBackend *blk_next(BlockBackend *blk);