f2fs: export ipu policy in debugfs

Export ipu_policy as a string in debugfs for better readability and
it can help us better understand some strategies of the file system.

Signed-off-by: Yangtao Li <frank.li@vivo.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/debug.c

@@ -354,6 +354,17 @@ static char *s_flag[] = {
 	[SBI_IS_FREEZING]	= " freezefs",
 };
 
+static const char *ipu_mode_names[F2FS_IPU_MAX] = {
+	[F2FS_IPU_FORCE]	= "FORCE",
+	[F2FS_IPU_SSR]		= "SSR",
+	[F2FS_IPU_UTIL]		= "UTIL",
+	[F2FS_IPU_SSR_UTIL]	= "SSR_UTIL",
+	[F2FS_IPU_FSYNC]	= "FSYNC",
+	[F2FS_IPU_ASYNC]	= "ASYNC",
+	[F2FS_IPU_NOCACHE]	= "NOCACHE",
+	[F2FS_IPU_HONOR_OPU_WRITE]	= "HONOR_OPU_WRITE",
+};
+
 static int stat_show(struct seq_file *s, void *v)
 {
 	struct f2fs_stat_info *si;
@@ -384,6 +395,19 @@ static int stat_show(struct seq_file *s, void *v)
 		seq_printf(s, "Current Time Sec: %llu / Mounted Time Sec: %llu\n\n",
 					ktime_get_boottime_seconds(),
 					SIT_I(si->sbi)->mounted_time);
+
+		seq_puts(s, "Policy:\n");
+		seq_puts(s, "  - IPU: [");
+		if (IS_F2FS_IPU_DISABLE(si->sbi)) {
+			seq_puts(s, " DISABLE");
+		} else {
+			unsigned long policy = SM_I(si->sbi)->ipu_policy;
+
+			for_each_set_bit(j, &policy, F2FS_IPU_MAX)
+				seq_printf(s, " %s", ipu_mode_names[j]);
+		}
+		seq_puts(s, " ]\n\n");
+
 		if (test_opt(si->sbi, DISCARD))
 			seq_printf(s, "Utilization: %u%% (%u valid blocks, %u discard blocks)\n",
 				si->utilization, si->valid_count, si->discard_blks);

fs/f2fs/segment.h

@@ -672,6 +672,7 @@ static inline int utilization(struct f2fs_sb_info *sbi)
 
 #define F2FS_IPU_DISABLE	0
 
+/* Modification on enum should be synchronized with ipu_mode_names array */
 enum {
 	F2FS_IPU_FORCE,
 	F2FS_IPU_SSR,