As the blobstore is being unlaoded, async esnap channel destructions may
be in flight. In such a case, spdk_bs_unload() needs to defer the unload
of the blobstore until channel destructions are complete.
The following commands lead to the illustrated states.
bdev_malloc_create -b malloc0
bdev_lvol_clone_bdev lvs1 malloc0 eclone
.---------. .--------.
| malloc0 |<--| eclone |
`---------' `--------'
bdev_lvol_snapshot lvs1/eclone snap
.---------. .------. .--------.
| malloc0 |<--| snap |<--| eclone |
`---------' `------' `--------'
bdev_lvol_clone lvs1/snap eclone
.--------.
,-| eclone |
.---------. .------.<-' `--------'
| malloc0 |<--| snap |
`---------' `------'<-. .-------.
`-| clone |
`-------'
As the blobstore is preparing to be unloaded spdk_blob_unload(snap) is
called once for eclone, once for clone, and once for snap. The last of
these calls happens just before spdk_bs_unload() is called.
spdk_blob_unload() needs to destroy channels on each thread. During this
thread iteration, spdk_bs_unload() starts. The work performed in the
iteration maintains a reference to the blob, and as such it
spdk_bs_unload() cannot do its work until the iteration is complete.
Change-Id: Id9b92ad73341fb3437441146110055c84ee6dc52
Signed-off-by: Mike Gerdts <mgerdts@nvidia.com>
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/14975
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Community-CI: Mellanox Build Bot
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
ba91ffbae1