[PATCH] mm/zswap: add crypto engine failures debugfs counter

[SeongJae Park]

compress_fail counts failures of general attempts to compress a given
apge into a size smaller than PAGE_SIZE.  It could be happened because
the content of the page is not easy to be compressed, or the crypto
engine error-ed for any reason.  Adda new debugfs file, namely
compress_engine_fail, for coutning the latter case.  Keep the
comress_fail count, since the failures due to the compression ratio
failure can be calculated by subtracting the new counter
(compress_engine_fail) value from that of the existing one
(compress_fail).

Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
---
 mm/zswap.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/mm/zswap.c b/mm/zswap.c
index 0fb940d03268..6b2144126fba 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -62,6 +62,8 @@ static u64 zswap_reject_reclaim_fail;
 static u64 zswap_reject_compress_fail;
 /* Compression into a size of <PAGE_SIZE failed */
 static u64 zswap_compress_fail;
+/* Compression failed by the crypto engine */
+static u64 zswap_compress_engine_fail;
 /* Compressed page was too big for the allocator to (optimally) store */
 static u64 zswap_reject_compress_poor;
 /* Load or writeback failed due to decompression failure */
@@ -988,6 +990,8 @@ static bool zswap_compress(struct page *page, struct zswap_entry *entry,
 	 */
 	if (comp_ret || dlen >= PAGE_SIZE) {
 		zswap_compress_fail++;
+		if (comp_ret)
+			zswap_compress_engine_fail++;
 		if (mem_cgroup_zswap_writeback_enabled(
 					folio_memcg(page_folio(page)))) {
 			comp_ret = 0;
@@ -1841,6 +1845,8 @@ static int zswap_debugfs_init(void)
 			   zswap_debugfs_root, &zswap_reject_compress_fail);
 	debugfs_create_u64("compress_fail", 0444,
 			   zswap_debugfs_root, &zswap_compress_fail);
+	debugfs_create_u64("compress_engine_fail", 0444,
+			   zswap_debugfs_root, &zswap_compress_engine_fail);
 	debugfs_create_u64("reject_compress_poor", 0444,
 			   zswap_debugfs_root, &zswap_reject_compress_poor);
 	debugfs_create_u64("decompress_fail", 0444,
-- 
2.39.5