252 lines
6.7 KiB
C
252 lines
6.7 KiB
C
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/*
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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) 2010, Oracle and/or its affiliates. All rights reserved.
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* Copyright (c) 2013 by Delphix. All rights reserved.
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*/
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#include <sys/types.h>
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#include <sys/param.h>
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#include <sys/errno.h>
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#include <sys/kmem.h>
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#include <sys/sunddi.h>
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#include <sys/zfs_ioctl.h>
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#include <sys/zfs_onexit.h>
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#include <sys/zvol.h>
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/*
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* ZFS kernel routines may add/delete callback routines to be invoked
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* upon process exit (triggered via the close operation from the /dev/zfs
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* driver).
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*
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* These cleanup callbacks are intended to allow for the accumulation
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* of kernel state across multiple ioctls. User processes participate
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* simply by opening ZFS_DEV. This causes the ZFS driver to do create
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* some private data for the file descriptor and generating a unique
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* minor number. The process then passes along that file descriptor to
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* each ioctl that might have a cleanup operation.
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*
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* Consumers of the onexit routines should call zfs_onexit_fd_hold() early
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* on to validate the given fd and add a reference to its file table entry.
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* This allows the consumer to do its work and then add a callback, knowing
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* that zfs_onexit_add_cb() won't fail with EBADF. When finished, consumers
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* should call zfs_onexit_fd_rele().
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*
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* A simple example is zfs_ioc_recv(), where we might create an AVL tree
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* with dataset/GUID mappings and then reuse that tree on subsequent
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* zfs_ioc_recv() calls.
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*
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* On the first zfs_ioc_recv() call, dmu_recv_stream() will kmem_alloc()
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* the AVL tree and pass it along with a callback function to
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* zfs_onexit_add_cb(). The zfs_onexit_add_cb() routine will register the
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* callback and return an action handle.
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*
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* The action handle is then passed from user space to subsequent
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* zfs_ioc_recv() calls, so that dmu_recv_stream() can fetch its AVL tree
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* by calling zfs_onexit_cb_data() with the device minor number and
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* action handle.
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*
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* If the user process exits abnormally, the callback is invoked implicitly
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* as part of the driver close operation. Once the user space process is
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* finished with the accumulated kernel state, it can also just call close(2)
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* on the cleanup fd to trigger the cleanup callback.
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*/
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void
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zfs_onexit_init(zfs_onexit_t **zop)
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{
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zfs_onexit_t *zo;
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zo = *zop = kmem_zalloc(sizeof (zfs_onexit_t), KM_SLEEP);
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mutex_init(&zo->zo_lock, NULL, MUTEX_DEFAULT, NULL);
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list_create(&zo->zo_actions, sizeof (zfs_onexit_action_node_t),
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offsetof(zfs_onexit_action_node_t, za_link));
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}
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void
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zfs_onexit_destroy(zfs_onexit_t *zo)
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{
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zfs_onexit_action_node_t *ap;
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mutex_enter(&zo->zo_lock);
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while ((ap = list_head(&zo->zo_actions)) != NULL) {
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list_remove(&zo->zo_actions, ap);
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mutex_exit(&zo->zo_lock);
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ap->za_func(ap->za_data);
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kmem_free(ap, sizeof (zfs_onexit_action_node_t));
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mutex_enter(&zo->zo_lock);
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}
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mutex_exit(&zo->zo_lock);
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list_destroy(&zo->zo_actions);
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mutex_destroy(&zo->zo_lock);
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kmem_free(zo, sizeof (zfs_onexit_t));
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}
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static int
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zfs_onexit_minor_to_state(minor_t minor, zfs_onexit_t **zo)
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{
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*zo = zfsdev_get_state(minor, ZST_ONEXIT);
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if (*zo == NULL)
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return (SET_ERROR(EBADF));
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return (0);
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}
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/*
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* Consumers might need to operate by minor number instead of fd, since
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* they might be running in another thread (e.g. txg_sync_thread). Callers
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* of this function must call zfs_onexit_fd_rele() when they're finished
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* using the minor number.
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*/
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int
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zfs_onexit_fd_hold(int fd, minor_t *minorp)
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{
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file_t *fp;
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zfs_onexit_t *zo;
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int error;
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fp = getf(fd);
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if (fp == NULL)
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return (SET_ERROR(EBADF));
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error = zfsdev_getminor(fp->f_file, minorp);
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if (error == 0)
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error = zfs_onexit_minor_to_state(*minorp, &zo);
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if (error)
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zfs_onexit_fd_rele(fd);
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return (error);
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}
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void
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zfs_onexit_fd_rele(int fd)
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{
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releasef(fd);
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}
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/*
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* Add a callback to be invoked when the calling process exits.
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*/
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int
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zfs_onexit_add_cb(minor_t minor, void (*func)(void *), void *data,
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uint64_t *action_handle)
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{
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zfs_onexit_t *zo;
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zfs_onexit_action_node_t *ap;
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int error;
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error = zfs_onexit_minor_to_state(minor, &zo);
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if (error)
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return (error);
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ap = kmem_alloc(sizeof (zfs_onexit_action_node_t), KM_SLEEP);
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list_link_init(&ap->za_link);
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ap->za_func = func;
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ap->za_data = data;
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mutex_enter(&zo->zo_lock);
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list_insert_tail(&zo->zo_actions, ap);
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mutex_exit(&zo->zo_lock);
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if (action_handle)
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*action_handle = (uint64_t)(uintptr_t)ap;
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return (0);
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}
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static zfs_onexit_action_node_t *
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zfs_onexit_find_cb(zfs_onexit_t *zo, uint64_t action_handle)
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{
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zfs_onexit_action_node_t *match;
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zfs_onexit_action_node_t *ap;
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list_t *l;
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ASSERT(MUTEX_HELD(&zo->zo_lock));
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match = (zfs_onexit_action_node_t *)(uintptr_t)action_handle;
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l = &zo->zo_actions;
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for (ap = list_head(l); ap != NULL; ap = list_next(l, ap)) {
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if (match == ap)
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break;
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}
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return (ap);
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}
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/*
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* Delete the callback, triggering it first if 'fire' is set.
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*/
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int
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zfs_onexit_del_cb(minor_t minor, uint64_t action_handle, boolean_t fire)
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{
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zfs_onexit_t *zo;
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zfs_onexit_action_node_t *ap;
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int error;
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error = zfs_onexit_minor_to_state(minor, &zo);
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if (error)
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return (error);
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mutex_enter(&zo->zo_lock);
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ap = zfs_onexit_find_cb(zo, action_handle);
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if (ap != NULL) {
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list_remove(&zo->zo_actions, ap);
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mutex_exit(&zo->zo_lock);
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if (fire)
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ap->za_func(ap->za_data);
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kmem_free(ap, sizeof (zfs_onexit_action_node_t));
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} else {
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mutex_exit(&zo->zo_lock);
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error = SET_ERROR(ENOENT);
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}
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return (error);
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}
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/*
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* Return the data associated with this callback. This allows consumers
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* of the cleanup-on-exit interfaces to stash kernel data across system
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* calls, knowing that it will be cleaned up if the calling process exits.
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*/
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int
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zfs_onexit_cb_data(minor_t minor, uint64_t action_handle, void **data)
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{
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zfs_onexit_t *zo;
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zfs_onexit_action_node_t *ap;
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int error;
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*data = NULL;
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error = zfs_onexit_minor_to_state(minor, &zo);
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if (error)
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return (error);
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mutex_enter(&zo->zo_lock);
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ap = zfs_onexit_find_cb(zo, action_handle);
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if (ap != NULL)
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*data = ap->za_data;
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else
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error = SET_ERROR(ENOENT);
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mutex_exit(&zo->zo_lock);
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return (error);
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}
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