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authorKonstantin Khlebnikov <khlebnikov@yandex-team.ru>2019-11-10 12:49:06 +0300
committerJan Kara <jack@suse.cz>2019-11-11 11:06:27 +0100
commit6fcbcec9cfc7b3c6a2c1f1a23ebacedff7073e0a (patch)
tree4552e3c0221e26fc3d0552ed677f553b54f668c5
parent355b9aae868512747c0ff90231e8ae8ea0278a60 (diff)
fs/quota: handle overflows of sysctl fs.quota.* and report as unsigned long
Quota statistics counted as 64-bit per-cpu counter. Reading sums per-cpu fractions as signed 64-bit int, filters negative values and then reports lower half as signed 32-bit int. Result may looks like: fs.quota.allocated_dquots = 22327 fs.quota.cache_hits = -489852115 fs.quota.drops = -487288718 fs.quota.free_dquots = 22083 fs.quota.lookups = -486883485 fs.quota.reads = 22327 fs.quota.syncs = 335064 fs.quota.writes = 3088689 Values bigger than 2^31-1 reported as negative. All counters except "allocated_dquots" and "free_dquots" are monotonic, thus they should be reported as is without filtering negative values. Kernel doesn't have generic helper for 64-bit sysctl yet, let's use at least unsigned long. Link: https://lore.kernel.org/r/157337934693.2078.9842146413181153727.stgit@buzz Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Signed-off-by: Jan Kara <jack@suse.cz>
-rw-r--r--fs/quota/dquot.c29
-rw-r--r--include/linux/quota.h2
2 files changed, 18 insertions, 13 deletions
diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 54a6626c2e9b..4639d53e96a3 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -2848,68 +2848,73 @@ EXPORT_SYMBOL(dquot_quotactl_sysfile_ops);
static int do_proc_dqstats(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
- unsigned int type = (int *)table->data - dqstats.stat;
+ unsigned int type = (unsigned long *)table->data - dqstats.stat;
+ s64 value = percpu_counter_sum(&dqstats.counter[type]);
+
+ /* Filter negative values for non-monotonic counters */
+ if (value < 0 && (type == DQST_ALLOC_DQUOTS ||
+ type == DQST_FREE_DQUOTS))
+ value = 0;
/* Update global table */
- dqstats.stat[type] =
- percpu_counter_sum_positive(&dqstats.counter[type]);
- return proc_dointvec(table, write, buffer, lenp, ppos);
+ dqstats.stat[type] = value;
+ return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
}
static struct ctl_table fs_dqstats_table[] = {
{
.procname = "lookups",
.data = &dqstats.stat[DQST_LOOKUPS],
- .maxlen = sizeof(int),
+ .maxlen = sizeof(unsigned long),
.mode = 0444,
.proc_handler = do_proc_dqstats,
},
{
.procname = "drops",
.data = &dqstats.stat[DQST_DROPS],
- .maxlen = sizeof(int),
+ .maxlen = sizeof(unsigned long),
.mode = 0444,
.proc_handler = do_proc_dqstats,
},
{
.procname = "reads",
.data = &dqstats.stat[DQST_READS],
- .maxlen = sizeof(int),
+ .maxlen = sizeof(unsigned long),
.mode = 0444,
.proc_handler = do_proc_dqstats,
},
{
.procname = "writes",
.data = &dqstats.stat[DQST_WRITES],
- .maxlen = sizeof(int),
+ .maxlen = sizeof(unsigned long),
.mode = 0444,
.proc_handler = do_proc_dqstats,
},
{
.procname = "cache_hits",
.data = &dqstats.stat[DQST_CACHE_HITS],
- .maxlen = sizeof(int),
+ .maxlen = sizeof(unsigned long),
.mode = 0444,
.proc_handler = do_proc_dqstats,
},
{
.procname = "allocated_dquots",
.data = &dqstats.stat[DQST_ALLOC_DQUOTS],
- .maxlen = sizeof(int),
+ .maxlen = sizeof(unsigned long),
.mode = 0444,
.proc_handler = do_proc_dqstats,
},
{
.procname = "free_dquots",
.data = &dqstats.stat[DQST_FREE_DQUOTS],
- .maxlen = sizeof(int),
+ .maxlen = sizeof(unsigned long),
.mode = 0444,
.proc_handler = do_proc_dqstats,
},
{
.procname = "syncs",
.data = &dqstats.stat[DQST_SYNCS],
- .maxlen = sizeof(int),
+ .maxlen = sizeof(unsigned long),
.mode = 0444,
.proc_handler = do_proc_dqstats,
},
diff --git a/include/linux/quota.h b/include/linux/quota.h
index f32dd270b8e3..27aab84fcbaa 100644
--- a/include/linux/quota.h
+++ b/include/linux/quota.h
@@ -263,7 +263,7 @@ enum {
};
struct dqstats {
- int stat[_DQST_DQSTAT_LAST];
+ unsigned long stat[_DQST_DQSTAT_LAST];
struct percpu_counter counter[_DQST_DQSTAT_LAST];
};