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bdev/ocf: take additional reference for ocf_cache

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Fixes #1498

When shutting down the application, it was possible to
reference stale ocf_cache pointer. This was the case
when two or more vbdev_ocf devices were based on top
of single cache bdev.

This issue did not occur outside of the shutdown case,
since RPC only allows deletion of the vbdev_ocf.
This erases on disk metadata and next run of the application,
would not detect such vbdev_ocf.

Shutdown meanwhile works different, by first stopping
the instance of running "ocf_mngt_cache" and later detaching
"core" devices (the ones being cached). This prevented
erasing the on disk metadata and allowed for restarted
application to detect vbdev_ocf.
See patch (1292ef2) for details.

Since references to ocf_cache are copied between vbdev_ocf
[see start_cache()], the reference count inside ocf_cache
was limited to original ocf_mngt_cache_start() and
management queue creation. First call into ocf_mngt_cache_stop()
released all references to ocf_cache. Leaving other
vbdev_ocfs pointing to released memory.

This patch works around this issue by increasing ref cnt
on ocf_cache for each vbdev based on top of it.
It allows to call into ocf_mngt_cache_stop(), but not
release the memory for ocf_cache until last vbdev.

Note:
A proper redesign here is in order:
- either rearranging structures to be based around single ocf_cache,
rather than multiple vbdev_ocf instances
- better use of OCF API to reduce book keeping logic in vbdev

There are plans to implement detach/attach in RPC,
so it should be a focus during that effort.

Signed-off-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/3574 (master)

(cherry picked from commit 1350922d09)
Change-Id: I560a7fbb1c052bf53970e655bdb60803c561a252
Signed-off-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/3593
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
This commit is contained in:
Tomasz Zawadzki 2020-07-28 10:43:06 -04:00
parent 71469b64ba
commit ab691e3d5a
2 changed files with 4 additions and 2 deletions
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3
module/bdev/ocf/vbdev_ocf.c
View File

@ -199,6 +199,7 @@ static void
unregister_finish(struct vbdev_ocf *vbdev)
{
spdk_bdev_destruct_done(&vbdev->exp_bdev, vbdev->state.stop_status);
ocf_mngt_cache_put(vbdev->ocf_cache);
vbdev_ocf_cache_ctx_put(vbdev->cache_ctx);
vbdev_ocf_mngt_continue(vbdev, 0);
}
@ -1059,6 +1060,7 @@ start_cache(struct vbdev_ocf *vbdev)
SPDK_NOTICELOG("OCF bdev %s connects to existing cache device %s\n",
vbdev->name, vbdev->cache.name);
vbdev->ocf_cache = existing;
ocf_mngt_cache_get(vbdev->ocf_cache);
vbdev->cache_ctx = ocf_cache_get_priv(existing);
vbdev_ocf_cache_ctx_get(vbdev->cache_ctx);
vbdev_ocf_mngt_continue(vbdev, 0);
@ -1079,6 +1081,7 @@ start_cache(struct vbdev_ocf *vbdev)
vbdev_ocf_mngt_exit(vbdev, unregister_path_dirty, rc);
return;
}
ocf_mngt_cache_get(vbdev->ocf_cache);
ocf_cache_set_priv(vbdev->ocf_cache, vbdev->cache_ctx);

3
test/ocf/ocf.sh
View File

@ -10,6 +10,5 @@ run_test "ocf_bdevperf_iotypes" "$testdir/integrity/bdevperf-iotypes.sh"
run_test "ocf_stats" "$testdir/integrity/stats.sh"
run_test "ocf_create_destruct" "$testdir/management/create-destruct.sh"
run_test "ocf_multicore" "$testdir/management/multicore.sh"
# Disabled due to issue #1498
# run_test "ocf_persistent_metadata" "$testdir/management/persistent-metadata.sh"
run_test "ocf_persistent_metadata" "$testdir/management/persistent-metadata.sh"
run_test "ocf_remove" "$testdir/management/remove.sh"