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block, block-backend: write some hot coroutine wrappers by hand

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The introduction of the graph lock is causing blk_get_geometry, a hot function
used in the I/O path, to create a coroutine.  However, the only part that really
needs to run in coroutine context is the call to bdrv_co_refresh_total_sectors,
which in turn only happens in the rare case of host CD-ROM devices.

So, write by hand the three wrappers on the path from blk_co_get_geometry to
bdrv_co_refresh_total_sectors, so that the coroutine wrapper is only created
if bdrv_nb_sectors actually calls bdrv_refresh_total_sectors.

Reported-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20230407153303.391121-9-pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Paolo Bonzini 2023-04-07 17:33:03 +02:00 • committed by Kevin Wolf
parent 9ed98cae15
commit 81f730d4d0
4 changed files with 52 additions and 4 deletions
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2
include/block/block-io.h
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@ -79,7 +79,7 @@ bdrv_co_truncate(BdrvChild *child, int64_t offset, bool exact,
PreallocMode prealloc, BdrvRequestFlags flags, Error **errp);
int64_t coroutine_fn GRAPH_RDLOCK bdrv_co_nb_sectors(BlockDriverState *bs);
int64_t co_wrapper_mixed_bdrv_rdlock bdrv_nb_sectors(BlockDriverState *bs);
int64_t coroutine_mixed_fn bdrv_nb_sectors(BlockDriverState *bs);
int64_t coroutine_fn GRAPH_RDLOCK bdrv_co_getlength(BlockDriverState *bs);
int64_t co_wrapper_mixed_bdrv_rdlock bdrv_getlength(BlockDriverState *bs);