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>
return bs->total_sectors;
}
+/*
+ * This wrapper is written by hand because this function is in the hot I/O path,
+ * via blk_get_geometry.
+ */
+int64_t coroutine_mixed_fn bdrv_nb_sectors(BlockDriverState *bs)
+{
+ BlockDriver *drv = bs->drv;
+ IO_CODE();
+
+ if (!drv)
+ return -ENOMEDIUM;
+
+ if (bs->bl.has_variable_length) {
+ int ret = bdrv_refresh_total_sectors(bs, bs->total_sectors);
+ if (ret < 0) {
+ return ret;
+ }
+ }
+
+ return bs->total_sectors;
+}
+
/**
* Return length in bytes on success, -errno on error.
* The length is always a multiple of BDRV_SECTOR_SIZE.
}
}
+/*
+ * This wrapper is written by hand because this function is in the hot I/O path,
+ * via blk_get_geometry.
+ */
+int64_t coroutine_mixed_fn blk_nb_sectors(BlockBackend *blk)
+{
+ BlockDriverState *bs = blk_bs(blk);
+
+ IO_CODE();
+
+ if (!bs) {
+ return -ENOMEDIUM;
+ } else {
+ return bdrv_nb_sectors(bs);
+ }
+}
+
/* return 0 as number of sectors if no device present or error */
void coroutine_fn blk_co_get_geometry(BlockBackend *blk,
uint64_t *nb_sectors_ptr)
*nb_sectors_ptr = ret < 0 ? 0 : ret;
}
+/*
+ * This wrapper is written by hand because this function is in the hot I/O path.
+ */
+void coroutine_mixed_fn blk_get_geometry(BlockBackend *blk,
+ uint64_t *nb_sectors_ptr)
+{
+ int64_t ret = blk_nb_sectors(blk);
+ *nb_sectors_ptr = ret < 0 ? 0 : ret;
+}
+
BlockAIOCB *blk_aio_preadv(BlockBackend *blk, int64_t offset,
QEMUIOVector *qiov, BdrvRequestFlags flags,
BlockCompletionFunc *cb, void *opaque)
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);
void coroutine_fn blk_co_get_geometry(BlockBackend *blk,
uint64_t *nb_sectors_ptr);
-void co_wrapper_mixed blk_get_geometry(BlockBackend *blk,
- uint64_t *nb_sectors_ptr);
+void blk_get_geometry(BlockBackend *blk, uint64_t *nb_sectors_ptr);
int64_t coroutine_fn blk_co_nb_sectors(BlockBackend *blk);
-int64_t co_wrapper_mixed blk_nb_sectors(BlockBackend *blk);
+int64_t blk_nb_sectors(BlockBackend *blk);
void *blk_try_blockalign(BlockBackend *blk, size_t size);
void *blk_blockalign(BlockBackend *blk, size_t size);