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https://github.com/versity/scoutfs.git
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e354fd18b1
I wanted to add a sysfs file that exports the fsid for the mount of a given device. But our use of sysfs was confusing and spread through super.c and counters.c. This moves the core of our sysfs use to sysfs.c. Instead of defining the per-mount dir as a kset we define it as an object with attributes which gives us a place to add an fsid attribute. counters still have their own whack of sysfs implementation. We'll let it keep it for now but we could move it into sysfs.c. It's just counter interation around the insane sysfs obj/attr/type nonsense. For now it just needs to know to add its counters dir as a child of the per-mount dir instead of adding it to the kset. Signed-off-by: Zach Brown <zab@versity.com>
133 lines
3.5 KiB
C
133 lines
3.5 KiB
C
/*
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* Copyright (C) 2016 Versity Software, Inc. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License v2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*/
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/fs.h>
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#include <linux/percpu_counter.h>
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#include "super.h"
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#include "sysfs.h"
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#include "counters.h"
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/*
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* Maintain simple percpu counters which are always ticking. sysfs
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* makes this a whole lot more noisy than it needs to be.
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*/
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#undef EXPAND_COUNTER
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#define EXPAND_COUNTER(which) { .name = __stringify(which), .mode = 0644 },
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static struct attribute scoutfs_counter_attrs[] = {
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EXPAND_EACH_COUNTER
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};
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/* zero BSS and + 1 makes this null terminated */
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#define NR_ATTRS ARRAY_SIZE(scoutfs_counter_attrs)
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static struct attribute *scoutfs_counter_attr_ptrs[NR_ATTRS + 1];
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static ssize_t scoutfs_counter_attr_show(struct kobject *kobj,
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struct attribute *attr, char *buf)
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{
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struct scoutfs_counters *counters;
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struct percpu_counter *pcpu;
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size_t index;
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/* use the index in the _attrs array to discover the pcpu pointer */
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counters = container_of(kobj, struct scoutfs_counters, kobj);
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index = attr - scoutfs_counter_attrs;
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pcpu = &counters->FIRST_COUNTER + index;
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return snprintf(buf, PAGE_SIZE, "%lld\n", percpu_counter_sum(pcpu));
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}
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static void scoutfs_counters_kobj_release(struct kobject *kobj)
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{
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struct scoutfs_counters *counters;
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counters = container_of(kobj, struct scoutfs_counters, kobj);
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complete(&counters->comp);
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}
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static const struct sysfs_ops scoutfs_counter_attr_ops = {
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.show = scoutfs_counter_attr_show,
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};
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static struct kobj_type scoutfs_counters_ktype = {
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.default_attrs = scoutfs_counter_attr_ptrs,
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.sysfs_ops = &scoutfs_counter_attr_ops,
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.release = scoutfs_counters_kobj_release,
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};
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int scoutfs_setup_counters(struct super_block *sb)
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{
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struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
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struct scoutfs_counters *counters;
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struct percpu_counter *pcpu;
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int ret;
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counters = kzalloc(sizeof(struct scoutfs_counters), GFP_KERNEL);
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if (!counters)
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return -ENOMEM;
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sbi->counters = counters;
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scoutfs_foreach_counter(sb, pcpu) {
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ret = percpu_counter_init(pcpu, 0, GFP_KERNEL);
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if (ret)
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goto out;
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}
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init_completion(&counters->comp);
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ret = kobject_init_and_add(&counters->kobj, &scoutfs_counters_ktype,
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scoutfs_sysfs_sb_dir(sb), "counters");
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out:
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if (ret) {
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/* tear down partial to avoid destroying null kobjs */
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scoutfs_foreach_counter(sb, pcpu)
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percpu_counter_destroy(pcpu);
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kfree(counters);
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sbi->counters = NULL;
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}
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return ret;
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}
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void scoutfs_destroy_counters(struct super_block *sb)
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{
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struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
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struct scoutfs_counters *counters = sbi->counters;
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struct percpu_counter *pcpu;
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/* this only destroys fully initialized counters */
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if (!counters)
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return;
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kobject_del(&counters->kobj);
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kobject_put(&counters->kobj);
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wait_for_completion(&counters->comp);
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scoutfs_foreach_counter(sb, pcpu)
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percpu_counter_destroy(pcpu);
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kfree(counters);
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sbi->counters = NULL;
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}
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void __init scoutfs_init_counters(void)
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{
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int i;
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/* not ARRAY_SIZE because that would clobber null term */
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for (i = 0; i < NR_ATTRS; i++)
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scoutfs_counter_attr_ptrs[i] = &scoutfs_counter_attrs[i];
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}
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