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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
128 lines
4.1 KiB
C
128 lines
4.1 KiB
C
/*
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* CDDL HEADER START
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*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License (the "License").
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* You may not use this file except in compliance with the License.
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*
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* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
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* or http://www.opensolaris.org/os/licensing.
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* See the License for the specific language governing permissions
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* and limitations under the License.
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*
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
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* If applicable, add the following below this CDDL HEADER, with the
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* fields enclosed by brackets "[]" replaced with your own identifying
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* information: Portions Copyright [yyyy] [name of copyright owner]
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*
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* CDDL HEADER END
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*/
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/*
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* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
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* Copyright (c) 2012, 2017 by Delphix. All rights reserved.
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*/
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#ifndef _SYS_DSL_SYNCTASK_H
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#define _SYS_DSL_SYNCTASK_H
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#include <sys/txg.h>
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#include <sys/zfs_context.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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struct dsl_pool;
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typedef int (dsl_checkfunc_t)(void *, dmu_tx_t *);
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typedef void (dsl_syncfunc_t)(void *, dmu_tx_t *);
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typedef void (dsl_sigfunc_t)(void *, dmu_tx_t *);
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typedef enum zfs_space_check {
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/*
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* Normal space check: if there is less than 3.2% free space,
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* the operation will fail. Operations which are logically
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* creating things should use this (e.g. "zfs create", "zfs snapshot").
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* User writes (via the ZPL / ZVOL) also fail at this point.
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*/
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ZFS_SPACE_CHECK_NORMAL,
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/*
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* Space check allows use of half the slop space. If there
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* is less than 1.6% free space, the operation will fail. Most
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* operations should use this (e.g. "zfs set", "zfs rename"),
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* because we want them to succeed even after user writes are failing,
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* so that they can be used as part of the space recovery process.
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*/
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ZFS_SPACE_CHECK_RESERVED,
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/*
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* Space check allows use of three quarters of the slop space.
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* If there is less than 0.8% free space, the operation will
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* fail.
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*/
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ZFS_SPACE_CHECK_EXTRA_RESERVED,
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/*
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* In all cases "zfs destroy" is expected to result in an net
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* reduction of space, except one. When the pool has a
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* checkpoint, space freed by "zfs destroy" will not actually
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* free anything internally. Thus, it starts failing after
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* three quarters of the slop space is exceeded.
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*/
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ZFS_SPACE_CHECK_DESTROY = ZFS_SPACE_CHECK_EXTRA_RESERVED,
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/*
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* A channel program can run a "zfs destroy" as part of its
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* script and therefore has the same space_check policy when
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* being evaluated.
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*/
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ZFS_SPACE_CHECK_ZCP_EVAL = ZFS_SPACE_CHECK_DESTROY,
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/*
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* No space check is performed. This level of space check should
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* be used cautiously as operations that use it can even run when
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* 0.8% capacity is left for use. In this scenario, if there is a
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* checkpoint, async destroys are suspended and any kind of freeing
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* can potentially add space instead of freeing it.
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*
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* See also the comments above spa_slop_shift.
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*/
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ZFS_SPACE_CHECK_NONE,
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ZFS_SPACE_CHECK_DISCARD_CHECKPOINT = ZFS_SPACE_CHECK_NONE,
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} zfs_space_check_t;
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typedef struct dsl_sync_task {
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txg_node_t dst_node;
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struct dsl_pool *dst_pool;
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uint64_t dst_txg;
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int dst_space;
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zfs_space_check_t dst_space_check;
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dsl_checkfunc_t *dst_checkfunc;
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dsl_syncfunc_t *dst_syncfunc;
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void *dst_arg;
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int dst_error;
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boolean_t dst_nowaiter;
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} dsl_sync_task_t;
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void dsl_sync_task_sync(dsl_sync_task_t *, dmu_tx_t *);
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int dsl_sync_task(const char *, dsl_checkfunc_t *,
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dsl_syncfunc_t *, void *, int, zfs_space_check_t);
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void dsl_sync_task_nowait(struct dsl_pool *, dsl_syncfunc_t *,
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void *, int, zfs_space_check_t, dmu_tx_t *);
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int dsl_early_sync_task(const char *, dsl_checkfunc_t *,
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dsl_syncfunc_t *, void *, int, zfs_space_check_t);
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void dsl_early_sync_task_nowait(struct dsl_pool *, dsl_syncfunc_t *,
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void *, int, zfs_space_check_t, dmu_tx_t *);
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int dsl_sync_task_sig(const char *, dsl_checkfunc_t *, dsl_syncfunc_t *,
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dsl_sigfunc_t *, void *, int, zfs_space_check_t);
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#ifdef __cplusplus
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}
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#endif
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#endif /* _SYS_DSL_SYNCTASK_H */
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