[PATCH v1] f2fs: fix max open zone constraints

[Wenjie Qi <qwjhust@gmail.com>]

We can get the number of remaining available zone
resources by subtracting the number of active logs from
the number of max active zones of zoned devices. We can
use these available zone resources to reduce the number
of pending bio when switching zones.
If max active zones is 0, there is no limit.

Signed-off-by: Wenjie Qi <qwjhust@gmail.com>
---
 fs/f2fs/data.c  | 32 +++++++++++++++++++++++++-------
 fs/f2fs/f2fs.h  |  2 ++
 fs/f2fs/super.c | 11 +++++++++++
 3 files changed, 38 insertions(+), 7 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index dce8defdf4c7..0b62ca296074 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -392,6 +392,19 @@ static void f2fs_zone_write_end_io(struct bio *bio)
 	complete(&io->zone_wait);
 	f2fs_write_end_io(bio);
 }
+
+static void f2fs_zone_write_end_io_nowait(struct bio *bio)
+{
+#ifdef CONFIG_F2FS_IOSTAT
+	struct bio_iostat_ctx *iostat_ctx = bio->bi_private;
+	struct f2fs_sb_info *sbi = iostat_ctx->sbi;
+#else
+	struct f2fs_sb_info *sbi = (struct f2fs_sb_info *)bio->bi_private;
+#endif
+
+	atomic_inc(&sbi->available_active_zones);
+	f2fs_write_end_io(bio);
+}
 #endif
 
 struct block_device *f2fs_target_device(struct f2fs_sb_info *sbi,
@@ -1085,14 +1098,19 @@ void f2fs_submit_page_write(struct f2fs_io_info *fio)
 		goto next;
 out:
 #ifdef CONFIG_BLK_DEV_ZONED
-	if (f2fs_sb_has_blkzoned(sbi) && btype < META &&
+	if (f2fs_sb_has_blkzoned(sbi) && sbi->max_active_zones && btype < META &&
 			is_end_zone_blkaddr(sbi, fio->new_blkaddr)) {
-		bio_get(io->bio);
-		reinit_completion(&io->zone_wait);
-		io->bi_private = io->bio->bi_private;
-		io->bio->bi_private = io;
-		io->bio->bi_end_io = f2fs_zone_write_end_io;
-		io->zone_pending_bio = io->bio;
+		if (!atomic_add_negative(-1, &sbi->available_active_zones)) {
+			io->bio->bi_end_io = f2fs_zone_write_end_io_nowait;
+		} else {
+			atomic_inc(&sbi->available_active_zones);
+			bio_get(io->bio);
+			reinit_completion(&io->zone_wait);
+			io->bi_private = io->bio->bi_private;
+			io->bio->bi_private = io;
+			io->bio->bi_end_io = f2fs_zone_write_end_io;
+			io->zone_pending_bio = io->bio;
+		}
 		__submit_merged_bio(io);
 	}
 #endif
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 65294e3b0bef..2aade367ac66 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1551,6 +1551,8 @@ struct f2fs_sb_info {
 
 #ifdef CONFIG_BLK_DEV_ZONED
 	unsigned int blocks_per_blkz;		/* F2FS blocks per zone */
+	unsigned int max_active_zones;		/* max zone resources of the zoned device */
+	atomic_t available_active_zones;	/* remaining zone resources for zone switch */
 #endif
 
 	/* for node-related operations */
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 206d03c82d96..6711283ff187 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -2385,6 +2385,12 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
 	if (err)
 		goto restore_opts;
 
+#ifdef CONFIG_BLK_DEV_ZONED
+	if (sbi->max_active_zones)
+		atomic_set(&sbi->available_active_zones,
+				sbi->max_active_zones - F2FS_OPTION(sbi).active_logs);
+#endif
+
 	/* flush outstanding errors before changing fs state */
 	flush_work(&sbi->s_error_work);
 
@@ -3932,6 +3938,11 @@ static int init_blkz_info(struct f2fs_sb_info *sbi, int devi)
 	if (!f2fs_sb_has_blkzoned(sbi))
 		return 0;
 
+	sbi->max_active_zones = bdev_max_active_zones(bdev);
+	if (sbi->max_active_zones)
+		atomic_set(&sbi->available_active_zones,
+				sbi->max_active_zones - F2FS_OPTION(sbi).active_logs);
+
 	zone_sectors = bdev_zone_sectors(bdev);
 	if (!is_power_of_2(zone_sectors)) {
 		f2fs_err(sbi, "F2FS does not support non power of 2 zone sizes\n");
-- 
2.34.1