blk-throttle: Only use seq_printf() in tg_prfill_limit()

Currently tg_prfill_limit() uses a combination of snprintf() and strcpy()
to generate the values parts of the limits string, before passing them as
arguments to seq_printf().

Convert to use only a sequence of seq_printf() calls per argument, which is
simpler.

Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240327094020.3505514-1-john.g.garry@oracle.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index f4850a6f860bbac8aba17aba9d217d83ec12f6a7..c515e1a96fad426628d1bc1bf01f19d5b657ff43 100644 (file)
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -1494,11 +1494,8 @@ static u64 tg_prfill_limit(struct seq_file *sf, struct blkg_policy_data *pd,
 {
        struct throtl_grp *tg = pd_to_tg(pd);
        const char *dname = blkg_dev_name(pd->blkg);
-       char bufs[4][21] = { "max", "max", "max", "max" };
        u64 bps_dft;
        unsigned int iops_dft;
-       char idle_time[26] = "";
-       char latency_time[26] = "";
 
        if (!dname)
                return 0;
@@ -1520,35 +1517,39 @@ static u64 tg_prfill_limit(struct seq_file *sf, struct blkg_policy_data *pd,
              tg->latency_target_conf == DFL_LATENCY_TARGET)))
                return 0;
 
-       if (tg->bps_conf[READ][off] != U64_MAX)
-               snprintf(bufs[0], sizeof(bufs[0]), "%llu",
-                       tg->bps_conf[READ][off]);
-       if (tg->bps_conf[WRITE][off] != U64_MAX)
-               snprintf(bufs[1], sizeof(bufs[1]), "%llu",
-                       tg->bps_conf[WRITE][off]);
-       if (tg->iops_conf[READ][off] != UINT_MAX)
-               snprintf(bufs[2], sizeof(bufs[2]), "%u",
-                       tg->iops_conf[READ][off]);
-       if (tg->iops_conf[WRITE][off] != UINT_MAX)
-               snprintf(bufs[3], sizeof(bufs[3]), "%u",
-                       tg->iops_conf[WRITE][off]);
+       seq_printf(sf, "%s", dname);
+       if (tg->bps_conf[READ][off] == U64_MAX)
+               seq_printf(sf, " rbps=max");
+       else
+               seq_printf(sf, " rbps=%llu", tg->bps_conf[READ][off]);
+
+       if (tg->bps_conf[WRITE][off] == U64_MAX)
+               seq_printf(sf, " wbps=max");
+       else
+               seq_printf(sf, " wbps=%llu", tg->bps_conf[WRITE][off]);
+
+       if (tg->iops_conf[READ][off] == UINT_MAX)
+               seq_printf(sf, " riops=max");
+       else
+               seq_printf(sf, " riops=%u", tg->iops_conf[READ][off]);
+
+       if (tg->iops_conf[WRITE][off] == UINT_MAX)
+               seq_printf(sf, " wiops=max");
+       else
+               seq_printf(sf, " wiops=%u", tg->iops_conf[WRITE][off]);
+
        if (off == LIMIT_LOW) {
                if (tg->idletime_threshold_conf == ULONG_MAX)
-                       strcpy(idle_time, " idle=max");
+                       seq_printf(sf, " idle=max");
                else
-                       snprintf(idle_time, sizeof(idle_time), " idle=%lu",
-                               tg->idletime_threshold_conf);
+                       seq_printf(sf, " idle=%lu", tg->idletime_threshold_conf);
 
                if (tg->latency_target_conf == ULONG_MAX)
-                       strcpy(latency_time, " latency=max");
+                       seq_printf(sf, " latency=max");
                else
-                       snprintf(latency_time, sizeof(latency_time),
-                               " latency=%lu", tg->latency_target_conf);
+                       seq_printf(sf, " latency=%lu", tg->latency_target_conf);
        }
-
-       seq_printf(sf, "%s rbps=%s wbps=%s riops=%s wiops=%s%s%s\n",
-                  dname, bufs[0], bufs[1], bufs[2], bufs[3], idle_time,
-                  latency_time);
+       seq_printf(sf, "\n");
        return 0;
 }