[PATCH] fsck.f2fs: flush device buffer before zone transition on zoned storage

[Daeho Jeong <daeho43@gmail.com>]

From: Daeho Jeong <daehojeong@google.com>

On zoned storage devices (F2FS_ZONED_HM), fsck.f2fs opens block devices
with buffered I/O (O_RDWR). When a curseg fills up its current zone and
moves to a new zone in find_next_free_block(), pending buffered writes
to the previous zone may still reside in the OS page cache / I/O queue.

As a result, issuing a write to the newly allocated zone can happen before
the device hardware finishes committing all blocks of the previous zone,
causing the hardware to see an additional open zone request that exceeds
the device's max open zone limit (e.g. open zones exceeded error).

Fix this by calling f2fs_fsync_device() right before allocating a new zone
when crossing zone boundaries (!(segno % segs_per_zone)). This flushes
all pending writes to physical media, ensuring the device hardware
auto-closes (FULL) the previous zone before opening the new zone.

Signed-off-by: Daeho Jeong <daehojeong@google.com>
---
 fsck/mount.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fsck/mount.c b/fsck/mount.c
index 6f640a0..3bd40fe 100644
--- a/fsck/mount.c
+++ b/fsck/mount.c
@@ -3073,6 +3073,9 @@ int find_next_free_block(struct f2fs_sb_info *sbi, u64 *to, int left,
 			if (!(segno % segs_per_zone)) {
 				u64 new_blkaddr = SM_I(sbi)->main_blkaddr;
 
+				if (c.zoned_model == F2FS_ZONED_HM)
+					f2fs_fsync_device();
+
 				ret = find_next_free_block(sbi, &new_blkaddr, 0,
 						want_type, true);
 				if (ret)
-- 
2.55.0.229.g6434b31f56-goog