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DAFS: Do not let VScheduleSalvage_r free vp

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In VScheduleSalvage_r, we were calling VCancelReservation_r, which has
the possibility of free'ing vp. Since we still use vp after doing this
(and since we're already inside VCancelReservation_r to begin with),
we must not free vp. Instead, just decrement nWaiters without
triggering any of the dtor code in VCancelReservation_r. This is safe
as long as all VScheduleSalvage_r callers ensure that they check to
free the vp if necessary, which they all do.

Thanks to Derrick Brashear.

Change-Id: Iebdbdf47c6307cd7c036b88ad4dbc25bc7a3279a
Reviewed-on: http://gerrit.openafs.org/3272
Tested-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>
This commit is contained in:
Andrew Deason 2010-11-05 14:34:05 -05:00 committed by Derrick Brashear
parent a8d1fe61f4
commit ef4b9e13ef
1 changed files with 16 additions and 1 deletions
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17
src/vol/volume.c
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@ -4963,6 +4963,10 @@ VOfflineForSalvage_r(struct Volume *vp)
* *
* @note this is one of the event handlers called by VCancelReservation_r * @note this is one of the event handlers called by VCancelReservation_r
* *
* @note the caller must check if the volume needs to be freed after calling
* this; the volume may not have any references or be on any lists after
* we return, and we do not free it
*
* @see VCancelReservation_r * @see VCancelReservation_r
* *
* @internal volume package internal use only. * @internal volume package internal use only.
@ -5237,6 +5241,10 @@ try_FSSYNC(Volume *vp, char *partName, int *code) {
* server over SALVSYNC. If we are not the fileserver, the request will be * server over SALVSYNC. If we are not the fileserver, the request will be
* sent to the fileserver over FSSYNC (FSYNC_VOL_FORCE_ERROR/FSYNC_SALVAGE). * sent to the fileserver over FSSYNC (FSYNC_VOL_FORCE_ERROR/FSYNC_SALVAGE).
* *
* @note the caller must check if the volume needs to be freed after calling
* this; the volume may not have any references or be on any lists after
* we return, and we do not free it
*
* @note DAFS only * @note DAFS only
* *
* @internal volume package internal use only. * @internal volume package internal use only.
@ -5329,7 +5337,14 @@ VScheduleSalvage_r(Volume * vp)
} }
} }
} }
VCancelReservation_r(vp);
/* NB: this is cancelling the reservation we obtained above, but we do
* not call VCancelReservation_r, since that may trigger the vp dtor,
* possibly free'ing the vp. We need to keep the vp around after
* this, as the caller may reference vp without any refs. Instead, it
* is the duty of the caller to inspect 'vp' after we return to see if
* needs to be freed. */
osi_Assert(--vp->nWaiters >= 0);
return ret; return ret;
} }
#endif /* SALVSYNC_BUILD_CLIENT || FSSYNC_BUILD_CLIENT */ #endif /* SALVSYNC_BUILD_CLIENT || FSSYNC_BUILD_CLIENT */