Dmitry Monakhov <dmonakhov@xxxxxxxxxx> writes:
> Generic pcpu counter has some memory overhead but it is negligible for
> modern systems, and embedded systems compiles without quota support.
> And code reuse is always good thing. This patch should fix complain
> from preemptive kernels which was introduced by dde9588853b1bde
Opps, sorry forget to add a sign.
Signed-off-by: Dmitry Monakhov <dmonakhov@xxxxxxxxxx>
BTW: Side effect of this patch is that proc files now contains
64 bits value, but i do not expect any problems here because only
very badly written applications with hard-coded buffer sizes will be
broken.
> ---
> fs/quota/dquot.c | 60 +++++++++++++++---------------------------------
> include/linux/quota.h | 28 ++++------------------
> 2 files changed, 24 insertions(+), 64 deletions(-)
>
> diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
> index 655a4c5..2b54548 100644
> --- a/fs/quota/dquot.c
> +++ b/fs/quota/dquot.c
> @@ -228,10 +228,6 @@ static struct hlist_head *dquot_hash;
>
> struct dqstats dqstats;
> EXPORT_SYMBOL(dqstats);
> -#ifdef CONFIG_SMP
> -struct dqstats *dqstats_pcpu;
> -EXPORT_SYMBOL(dqstats_pcpu);
> -#endif
>
> static qsize_t inode_get_rsv_space(struct inode *inode);
> static void __dquot_initialize(struct inode *inode, int type);
> @@ -676,22 +672,6 @@ static void prune_dqcache(int count)
> }
> }
>
> -static int dqstats_read(unsigned int type)
> -{
> - int count = 0;
> -#ifdef CONFIG_SMP
> - int cpu;
> - for_each_possible_cpu(cpu)
> - count += per_cpu_ptr(dqstats_pcpu, cpu)->stat[type];
> - /* Statistics reading is racy, but absolute accuracy isn't required */
> - if (count < 0)
> - count = 0;
> -#else
> - count = dqstats.stat[type];
> -#endif
> - return count;
> -}
> -
> /*
> * This is called from kswapd when we think we need some
> * more memory
> @@ -704,7 +684,8 @@ static int shrink_dqcache_memory(int nr, gfp_t gfp_mask)
> prune_dqcache(nr);
> spin_unlock(&dq_list_lock);
> }
> - return (dqstats_read(DQST_FREE_DQUOTS)/100) * sysctl_vfs_cache_pressure;
> + return (percpu_counter_sum_positive(dqstats.cntp + DQST_FREE_DQUOTS) /
> + 100) * sysctl_vfs_cache_pressure;
> }
>
> static struct shrinker dqcache_shrinker = {
> @@ -2509,68 +2490,66 @@ const struct quotactl_ops vfs_quotactl_ops = {
> static int do_proc_dqstats(struct ctl_table *table, int write,
> void __user *buffer, size_t *lenp, loff_t *ppos)
> {
> -#ifdef CONFIG_SMP
> /* Update global table */
> - unsigned int type = (int *)table->data - dqstats.stat;
> - dqstats.stat[type] = dqstats_read(type);
> -#endif
> - return proc_dointvec(table, write, buffer, lenp, ppos);
> + unsigned int type = (s64 *)table->data - dqstats.stat;
> + dqstats.stat[type] = percpu_counter_sum_positive(dqstats.cntp + type);
> + return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
> }
>
> static ctl_table fs_dqstats_table[] = {
> {
> .procname = "lookups",
> .data = &dqstats.stat[DQST_LOOKUPS],
> - .maxlen = sizeof(int),
> + .maxlen = sizeof(s64),
> .mode = 0444,
> .proc_handler = do_proc_dqstats,
> },
> {
> .procname = "drops",
> .data = &dqstats.stat[DQST_DROPS],
> - .maxlen = sizeof(int),
> + .maxlen = sizeof(s64),
> .mode = 0444,
> .proc_handler = do_proc_dqstats,
> },
> {
> .procname = "reads",
> .data = &dqstats.stat[DQST_READS],
> - .maxlen = sizeof(int),
> + .maxlen = sizeof(s64),
> .mode = 0444,
> .proc_handler = do_proc_dqstats,
> },
> {
> .procname = "writes",
> .data = &dqstats.stat[DQST_WRITES],
> - .maxlen = sizeof(int),
> + .maxlen = sizeof(s64),
> .mode = 0444,
> .proc_handler = do_proc_dqstats,
> },
> {
> .procname = "cache_hits",
> .data = &dqstats.stat[DQST_CACHE_HITS],
> - .maxlen = sizeof(int),
> + .maxlen = sizeof(s64),
> .mode = 0444,
> .proc_handler = do_proc_dqstats,
> },
> {
> .procname = "allocated_dquots",
> .data = &dqstats.stat[DQST_ALLOC_DQUOTS],
> - .maxlen = sizeof(int),
> + .maxlen = sizeof(s64),
> .mode = 0444,
> .proc_handler = do_proc_dqstats,
> },
> {
> .procname = "free_dquots",
> .data = &dqstats.stat[DQST_FREE_DQUOTS],
> - .maxlen = sizeof(int),
> + .maxlen = sizeof(s64),
> .mode = 0444,
> .proc_handler = do_proc_dqstats,
> },
> {
> .procname = "syncs",
> .data = &dqstats.stat[DQST_SYNCS],
> - .maxlen = sizeof(int),
> + .maxlen = sizeof(s64),
> .mode = 0444,
> .proc_handler = do_proc_dqstats,
> },
> @@ -2606,7 +2585,7 @@ static ctl_table sys_table[] = {
>
> static int __init dquot_init(void)
> {
> - int i;
> + int i, ret;
> unsigned long nr_hash, order;
>
> printk(KERN_NOTICE "VFS: Disk quotas %s\n", __DQUOT_VERSION__);
> @@ -2624,12 +2603,11 @@ static int __init dquot_init(void)
> if (!dquot_hash)
> panic("Cannot create dquot hash table");
>
> -#ifdef CONFIG_SMP
> - dqstats_pcpu = alloc_percpu(struct dqstats);
> - if (!dqstats_pcpu)
> - panic("Cannot create dquot stats table");
> -#endif
> - memset(&dqstats, 0, sizeof(struct dqstats));
> + for(i = 0; i < _DQST_DQSTAT_LAST; i++) {
> + ret = percpu_counter_init(dqstats.cntp + i, 0);
> + if (ret)
> + panic("Cannot create dquot stat counters");
> + }
>
> /* Find power-of-two hlist_heads which can fit into allocation */
> nr_hash = (1UL << order) * PAGE_SIZE / sizeof(struct hlist_head);
> diff --git a/include/linux/quota.h b/include/linux/quota.h
> index 7126a15..edd57d9 100644
> --- a/include/linux/quota.h
> +++ b/include/linux/quota.h
> @@ -174,8 +174,7 @@ enum {
> #include <linux/rwsem.h>
> #include <linux/spinlock.h>
> #include <linux/wait.h>
> -#include <linux/percpu.h>
> -#include <linux/smp.h>
> +#include <linux/percpu_counter.h>
>
> #include <linux/dqblk_xfs.h>
> #include <linux/dqblk_v1.h>
> @@ -253,29 +252,12 @@ enum {
> };
>
> struct dqstats {
> - int stat[_DQST_DQSTAT_LAST];
> + struct percpu_counter cntp[_DQST_DQSTAT_LAST];
> + s64 stat[_DQST_DQSTAT_LAST];
> };
> -
> -extern struct dqstats *dqstats_pcpu;
> extern struct dqstats dqstats;
> -
> -static inline void dqstats_inc(unsigned int type)
> -{
> -#ifdef CONFIG_SMP
> - per_cpu_ptr(dqstats_pcpu, smp_processor_id())->stat[type]++;
> -#else
> - dqstats.stat[type]++;
> -#endif
> -}
> -
> -static inline void dqstats_dec(unsigned int type)
> -{
> -#ifdef CONFIG_SMP
> - per_cpu_ptr(dqstats_pcpu, smp_processor_id())->stat[type]--;
> -#else
> - dqstats.stat[type]--;
> -#endif
> -}
> +#define dqstats_inc(type) percpu_counter_inc(&dqstats.cntp[(type)])
> +#define dqstats_dec(type) percpu_counter_dec(&dqstats.cntp[(type)])
>
> #define DQ_MOD_B 0 /* dquot modified since read */
> #define DQ_BLKS_B 1 /* uid/gid has been warned about blk limit */
--
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