[PATCH] f2fs: fix max open zone constraints

[Wenjie]

From: Wenjie Qi <qwjhust@xxxxxxxxx>

1. If the max active zones of zoned devices are less than the active logs of F2FS, the device may error due to insufficient zone resources when multiple active logs are being written at the same time.

2. 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.

Signed-off-by: Wenjie Qi <qwjhust@xxxxxxxxx>
---
 fs/f2fs/data.c  | 35 +++++++++++++++++++++++++++++------
 fs/f2fs/f2fs.h  |  3 +++
 fs/f2fs/super.c | 11 +++++++++++
 3 files changed, 43 insertions(+), 6 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index dce8defdf4c7..b6809a619171 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -392,6 +392,21 @@ 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
+	
+	spin_lock(&sbi->available_active_zones_lock);
+	sbi->available_active_zones++;
+	spin_unlock(&sbi->available_active_zones_lock);
+	f2fs_write_end_io(bio);
+}
 #endif
 
 struct block_device *f2fs_target_device(struct f2fs_sb_info *sbi,
@@ -1087,12 +1102,20 @@ void f2fs_submit_page_write(struct f2fs_io_info *fio)
 #ifdef CONFIG_BLK_DEV_ZONED
 	if (f2fs_sb_has_blkzoned(sbi) && 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;
+		spin_lock_bh(&sbi->available_active_zones_lock);
+		if (sbi->available_active_zones > 0){
+			sbi->available_active_zones--;
+			spin_unlock_bh(&sbi->available_active_zones_lock);
+			io->bio->bi_end_io = f2fs_zone_write_end_io_nowait;
+		}else{
+			spin_unlock_bh(&sbi->available_active_zones_lock);
+			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..8637eea1dfb8 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1551,6 +1551,9 @@ 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 */
+	unsigned int available_active_zones;		/* remaining available zone resources for active logs */
+	spinlock_t available_active_zones_lock;		/* for available zone resources */
 #endif
 
 	/* for node-related operations */
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 206d03c82d96..84f390e4ef49 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -3932,6 +3932,17 @@ 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 && (sbi->max_active_zones < F2FS_OPTION(sbi).active_logs)) {
+		f2fs_err(sbi,
+			"zoned: max active zones %u is too small, need at least %u active zones",
+				 sbi->max_active_zones, F2FS_OPTION(sbi).active_logs);
+		return -EINVAL;
+	}
+
+	sbi->available_active_zones = sbi->max_active_zones - F2FS_OPTION(sbi).active_logs;
+	spin_lock_init(&sbi->available_active_zones_lock);
+
 	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