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OpenZFS 9425 - channel programs can be interrupted

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Problem Statement
=================
ZFS Channel program scripts currently require a timeout, so that hung or
long-running scripts return a timeout error instead of causing ZFS to get
wedged. This limit can currently be set up to 100 million Lua instructions.
Even with a limit in place, it would be desirable to have a sys admin
(support engineer) be able to cancel a script that is taking a long time.

Proposed Solution
=================
Make it possible to abort a channel program by sending an interrupt signal.In
the underlying txg_wait_sync function, switch the cv_wait to a cv_wait_sig to
catch the signal. Once a signal is encountered, the dsl_sync_task function can
install a Lua hook that will get called before the Lua interpreter executes a
new line of code. The dsl_sync_task can resume with a standard txg_wait_sync
call and wait for the txg to complete.  Meanwhile, the hook will abort the
script and indicate that the channel program was canceled. The kernel returns
a EINTR to indicate that the channel program run was canceled.

Porting notes: Added missing return value from cv_wait_sig()

Authored by: Don Brady <don.brady@delphix.com>
Reviewed by: Sebastien Roy <sebastien.roy@delphix.com>
Reviewed by: Serapheim Dimitropoulos <serapheim.dimitro@delphix.com>
Reviewed by: Matt Ahrens <matt@delphix.com>
Reviewed by: Sara Hartse <sara.hartse@delphix.com>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Approved by: Robert Mustacchi <rm@joyent.com>
Ported-by: Don Brady <don.brady@delphix.com>
Signed-off-by: Don Brady <don.brady@delphix.com>

OpenZFS-issue: https://www.illumos.org/issues/9425
OpenZFS-commit: https://github.com/illumos/illumos-gate/commit/d0cb1fb926
Closes #8904
This commit is contained in:
Don Brady
2019-06-22 16:51:46 -07:00
committed by Tony Hutter
parent cbb9154958
commit e625030c11
13 changed files with 323 additions and 97 deletions
Download Patch File Download Diff File Expand all files Collapse all files
module/spl/spl-condvar.c
+18 -1
View File
@@ -29,6 +29,12 @@
#include <linux/hrtimer.h>
#include <linux/compiler_compat.h>
#include <linux/sched.h>
#ifdef HAVE_SCHED_SIGNAL_HEADER
#include <linux/sched/signal.h>
#endif
void
__cv_init(kcondvar_t *cvp, char *name, kcv_type_t type, void *arg)
{
@@ -144,10 +150,21 @@ __cv_wait_io(kcondvar_t *cvp, kmutex_t *mp)
}
EXPORT_SYMBOL(__cv_wait_io);
void
int
__cv_wait_io_sig(kcondvar_t *cvp, kmutex_t *mp)
{
cv_wait_common(cvp, mp, TASK_INTERRUPTIBLE, 1);
return (signal_pending(current) ? 0 : 1);
}
EXPORT_SYMBOL(__cv_wait_io_sig);
int
__cv_wait_sig(kcondvar_t *cvp, kmutex_t *mp)
{
cv_wait_common(cvp, mp, TASK_INTERRUPTIBLE, 0);
return (signal_pending(current) ? 0 : 1);
}
EXPORT_SYMBOL(__cv_wait_sig);