When `dmu_tx_assign` is called from `zil_lwb_write_issue`, it's possible
for either `ERESTART` or `EIO` to be returned.
If `ERESTART` is returned, this will cause an assertion to fail directly
in `zil_lwb_write_issue`, where the code assumes the return value is
`EIO` if `dmu_tx_assign` returns a non-zero value. This can occur if the
SPA is suspended when `dmu_tx_assign` is called, and most often occurs
when running `zloop`.
If `EIO` is returned, this can cause assertions to fail elsewhere in the
ZIL code. For example, `zil_commit_waiter_timeout` contains the
following logic:
lwb_t *nlwb = zil_lwb_write_issue(zilog, lwb);
ASSERT3S(lwb->lwb_state, !=, LWB_STATE_OPENED);
In this case, if `dmu_tx_assign` returned `EIO` from within
`zil_lwb_write_issue`, the `lwb` variable passed in will not be issued
to disk. Thus, it's `lwb_state` field will remain `LWB_STATE_OPENED` and
this assertion will fail. `zil_commit_waiter_timeout` assumes that after
it calls `zil_lwb_write_issue`, the `lwb` will be issued to disk, and
doesn't handle the case where this is not true; i.e. it doesn't handle
the case where `dmu_tx_assign` returns `EIO`.
This change modifies `zil_lwb_write_issue` to verify that the return
code from `dmu_tx_assign` is either `ERESTART` or `0`.
If `EIO` is returned, the system will panic. This behavior is similar to
how we use `VERIFY0` when calling `dmu_tx_assign` elsewhere in the ZFS
code.
If `ERESTART` is returned, `zil_lwb_write_issue` will retry the
operation, and continually attempt to assign the transation until it
succeeds.
Upstream bugs: DLPX-54873
You can view, comment on, or merge this pull request online at:
https://github.com/openzfs/openzfs/pull/507
-- Commit Summary --
* 0000 ztest assertion failure in zil_lwb_write_issue (v2)
-- File Changes --
M usr/src/uts/common/fs/zfs/zil.c (23)
-- Patch Links --
https://github.com/openzfs/openzfs/pull/507.patch
https://github.com/openzfs/openzfs/pull/507.diff
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