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There are some issues with the way the seq_file interface is implemented for kstats backed by linked lists (zfs_dbgmsgs and certain per-pool debugging info): * We don't account for the fact that seq_file sometimes visits a node multiple times, which results in missing messages when read through procfs. * We don't keep separate state for each reader of a file, so concurrent readers will receive incorrect results. * We don't account for the fact that entries may have been removed from the list between read syscalls, so reading from these files in procfs can cause the system to crash. This change fixes these issues and adds procfs_list, a wrapper around a linked list which abstracts away the details of implementing the seq_file interface for a list and exposing the contents of the list through procfs. Reviewed by: Don Brady <don.brady@delphix.com> Reviewed-by: Serapheim Dimitropoulos <serapheim@delphix.com> Reviewed by: Brad Lewis <brad.lewis@delphix.com> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: John Gallagher <john.gallagher@delphix.com> External-issue: LX-1211 Closes #7819
72 lines
2.1 KiB
C
72 lines
2.1 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) 2018 by Delphix. All rights reserved.
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*/
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#ifndef _SPL_PROCFS_LIST_H
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#define _SPL_PROCFS_LIST_H
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#include <sys/kstat.h>
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#include <sys/mutex.h>
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#include <linux/proc_fs.h>
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#include <linux/seq_file.h>
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typedef struct procfs_list procfs_list_t;
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struct procfs_list {
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/* Accessed only by user of a procfs_list */
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void *pl_private;
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/*
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* Accessed both by user of a procfs_list and by procfs_list
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* implementation
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*/
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kmutex_t pl_lock;
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list_t pl_list;
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/* Accessed only by procfs_list implementation */
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uint64_t pl_next_id;
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int (*pl_show)(struct seq_file *f, void *p);
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int (*pl_show_header)(struct seq_file *f);
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int (*pl_clear)(procfs_list_t *procfs_list);
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size_t pl_node_offset;
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kstat_proc_entry_t pl_kstat_entry;
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};
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typedef struct procfs_list_node {
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list_node_t pln_link;
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uint64_t pln_id;
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} procfs_list_node_t;
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void procfs_list_install(const char *module,
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const char *name,
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procfs_list_t *procfs_list,
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int (*show)(struct seq_file *f, void *p),
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int (*show_header)(struct seq_file *f),
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int (*clear)(procfs_list_t *procfs_list),
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size_t procfs_list_node_off);
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void procfs_list_uninstall(procfs_list_t *procfs_list);
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void procfs_list_destroy(procfs_list_t *procfs_list);
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void procfs_list_add(procfs_list_t *procfs_list, void *p);
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#endif /* _SPL_PROCFS_LIST_H */
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