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blk-cgroup: refactor blkcg_print_stat 

Factor out a helper to deal with a single blkcg_gq to make the code a
little bit easier to follow.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20210810152623.1796144-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2021-08-10 17:26:22 +02:00 committed by Jens Axboe
parent 3973e15fa5
commit 49cb5168a7
1 changed files with 76 additions and 76 deletions
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152
block/blk-cgroup.c
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@ -870,6 +870,81 @@ static void blkcg_fill_root_iostats(void)
}
}
static void blkcg_print_one_stat(struct blkcg_gq *blkg, struct seq_file *s)
{
struct blkg_iostat_set *bis = &blkg->iostat;
u64 rbytes, wbytes, rios, wios, dbytes, dios;
bool has_stats = false;
const char *dname;
unsigned seq;
char *buf;
size_t size = seq_get_buf(s, &buf), off = 0;
int i;
if (!blkg->online)
return;
dname = blkg_dev_name(blkg);
if (!dname)
return;
/*
* Hooray string manipulation, count is the size written NOT
* INCLUDING THE \0, so size is now count+1 less than what we
* had before, but we want to start writing the next bit from
* the \0 so we only add count to buf.
*/
off += scnprintf(buf+off, size-off, "%s ", dname);
do {
seq = u64_stats_fetch_begin(&bis->sync);
rbytes = bis->cur.bytes[BLKG_IOSTAT_READ];
wbytes = bis->cur.bytes[BLKG_IOSTAT_WRITE];
dbytes = bis->cur.bytes[BLKG_IOSTAT_DISCARD];
rios = bis->cur.ios[BLKG_IOSTAT_READ];
wios = bis->cur.ios[BLKG_IOSTAT_WRITE];
dios = bis->cur.ios[BLKG_IOSTAT_DISCARD];
} while (u64_stats_fetch_retry(&bis->sync, seq));
if (rbytes || wbytes || rios || wios) {
has_stats = true;
off += scnprintf(buf+off, size-off,
"rbytes=%llu wbytes=%llu rios=%llu wios=%llu dbytes=%llu dios=%llu",
rbytes, wbytes, rios, wios,
dbytes, dios);
}
if (blkcg_debug_stats && atomic_read(&blkg->use_delay)) {
has_stats = true;
off += scnprintf(buf+off, size-off, " use_delay=%d delay_nsec=%llu",
atomic_read(&blkg->use_delay),
atomic64_read(&blkg->delay_nsec));
}
for (i = 0; i < BLKCG_MAX_POLS; i++) {
struct blkcg_policy *pol = blkcg_policy[i];
size_t written;
if (!blkg->pd[i] || !pol->pd_stat_fn)
continue;
written = pol->pd_stat_fn(blkg->pd[i], buf+off, size-off);
if (written)
has_stats = true;
off += written;
}
if (has_stats) {
if (off < size - 1) {
off += scnprintf(buf+off, size-off, "\n");
seq_commit(s, off);
} else {
seq_commit(s, -1);
}
}
}
static int blkcg_print_stat(struct seq_file *sf, void *v)
{
struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
@ -881,86 +956,11 @@ static int blkcg_print_stat(struct seq_file *sf, void *v)
cgroup_rstat_flush(blkcg->css.cgroup);
rcu_read_lock();
hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) {
struct blkg_iostat_set *bis = &blkg->iostat;
const char *dname;
char *buf;
u64 rbytes, wbytes, rios, wios, dbytes, dios;
size_t size = seq_get_buf(sf, &buf), off = 0;
int i;
bool has_stats = false;
unsigned seq;
spin_lock_irq(&blkg->q->queue_lock);
if (!blkg->online)
goto skip;
dname = blkg_dev_name(blkg);
if (!dname)
goto skip;
/*
* Hooray string manipulation, count is the size written NOT
* INCLUDING THE \0, so size is now count+1 less than what we
* had before, but we want to start writing the next bit from
* the \0 so we only add count to buf.
*/
off += scnprintf(buf+off, size-off, "%s ", dname);
do {
seq = u64_stats_fetch_begin(&bis->sync);
rbytes = bis->cur.bytes[BLKG_IOSTAT_READ];
wbytes = bis->cur.bytes[BLKG_IOSTAT_WRITE];
dbytes = bis->cur.bytes[BLKG_IOSTAT_DISCARD];
rios = bis->cur.ios[BLKG_IOSTAT_READ];
wios = bis->cur.ios[BLKG_IOSTAT_WRITE];
dios = bis->cur.ios[BLKG_IOSTAT_DISCARD];
} while (u64_stats_fetch_retry(&bis->sync, seq));
if (rbytes || wbytes || rios || wios) {
has_stats = true;
off += scnprintf(buf+off, size-off,
"rbytes=%llu wbytes=%llu rios=%llu wios=%llu dbytes=%llu dios=%llu",
rbytes, wbytes, rios, wios,
dbytes, dios);
}
if (blkcg_debug_stats && atomic_read(&blkg->use_delay)) {
has_stats = true;
off += scnprintf(buf+off, size-off,
" use_delay=%d delay_nsec=%llu",
atomic_read(&blkg->use_delay),
(unsigned long long)atomic64_read(&blkg->delay_nsec));
}
for (i = 0; i < BLKCG_MAX_POLS; i++) {
struct blkcg_policy *pol = blkcg_policy[i];
size_t written;
if (!blkg->pd[i] || !pol->pd_stat_fn)
continue;
written = pol->pd_stat_fn(blkg->pd[i], buf+off, size-off);
if (written)
has_stats = true;
off += written;
}
if (has_stats) {
if (off < size - 1) {
off += scnprintf(buf+off, size-off, "\n");
seq_commit(sf, off);
} else {
seq_commit(sf, -1);
}
}
skip:
blkcg_print_one_stat(blkg, sf);
spin_unlock_irq(&blkg->q->queue_lock);
}
rcu_read_unlock();
return 0;
}