[PATCH 1/3] f2fs: fix to account entry_cnt for all write bios

[Chao Yu <chao@kernel.org>]

From: Chao Yu <chao@kernel.org>

Commit f32744a8b83d ("f2fs: introduce max_atc_write_bio_entry_cnt")
tracks the number of entries queued to a write bio via entry_cnt, so
that f2fs_write_end_io() can offload the completion of a write bio with
too many entries to sbi->wq if it is called in atomic context.

However, entry_cnt is only increased in f2fs_submit_page_write() and
f2fs_submit_cache_write(), it misses below write paths:
- f2fs_submit_page_bio(): single folio write bio.
- add_bio_entry(): the first folio of an IPU write bio.
- add_ipu_page(): folios merged into an IPU write bio.

So entry_cnt of these bios is less than the actual number of folios,
and a merged IPU write bio, which may contain up to BIO_MAX_VECS folios,
will never be offloaded to sbi->wq, then it may be completed in atomic
context with high latency. Let's fix to account entry_cnt in all above
paths.

Cc: stable@kernel.org
Fixes: f32744a8b83d ("f2fs: introduce max_atc_write_bio_entry_cnt")
Signed-off-by: Chao Yu <chao@kernel.org>
---
 fs/f2fs/data.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index a8d39add5cbe..16ab2c693aa9 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -870,6 +870,9 @@ int f2fs_submit_page_bio(struct f2fs_io_info *fio)
 			fio_folio->index, fio, GFP_NOIO);
 	bio_add_folio_nofail(bio, data_folio, folio_size(data_folio), 0);
 
+	if (!is_read_io(fio->op))
+		F2FS_BIO(bio)->entry_cnt++;
+
 	if (fio->io_wbc && !is_read_io(fio->op))
 		wbc_account_cgroup_owner(fio->io_wbc, fio_folio, PAGE_SIZE);
 
@@ -940,6 +943,7 @@ static void add_bio_entry(struct f2fs_sb_info *sbi, struct bio *bio,
 	bio_get(bio);
 
 	bio_add_folio_nofail(bio, folio, folio_size(folio), 0);
+	F2FS_BIO(bio)->entry_cnt++;
 
 	f2fs_down_write(&io->bio_list_lock);
 	list_add_tail(&be->list, &io->bio_list);
@@ -980,6 +984,7 @@ static int add_ipu_page(struct f2fs_io_info *fio, struct bio **bio,
 					fio_folio->mapping->host,
 					fio_folio->index, fio) &&
 			    bio_add_folio(*bio, folio, folio_size(folio), 0)) {
+				F2FS_BIO(*bio)->entry_cnt++;
 				ret = 0;
 				break;
 			}
-- 
2.49.0