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Message-Id: <20260120091215.62608-1-chao@kernel.org>
Date: Tue, 20 Jan 2026 17:12:14 +0800
From: Chao Yu <chao@...nel.org>
To: jaegeuk@...nel.org
Cc: linux-f2fs-devel@...ts.sourceforge.net,
linux-kernel@...r.kernel.org,
Chao Yu <chao@...nel.org>
Subject: [PATCH v2 1/2] f2fs: check skipped write in f2fs_enable_checkpoint()
This patch introduces sbi->nr_pages[F2FS_SKIPPED_WRITE] to record any
skipped write during data flush in f2fs_enable_checkpoint().
So in the loop of data flush, if there is any skipped write in previous
flush, let's retry sync_inode_sb(), otherwise, all dirty data written
before f2fs_enable_checkpoint() should have been persisted, then break
the retry loop.
Signed-off-by: Chao Yu <chao@...nel.org>
---
v2:
- update F2FS_SKIPPED_WRITE only when a) wbc->sync_mode is WB_SYNC_ALL
and b) return value of f2fs_write_cache_pages() is non-zero.
fs/f2fs/data.c | 19 +++++++++++++++++++
fs/f2fs/f2fs.h | 2 ++
fs/f2fs/super.c | 37 +++++++++++++++++++++++++++++++++----
3 files changed, 54 insertions(+), 4 deletions(-)
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index d509172b51df..25b4d3f21fa7 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -3495,6 +3495,16 @@ static inline void account_writeback(struct inode *inode, bool inc)
f2fs_up_read(&F2FS_I(inode)->i_sem);
}
+static inline void update_skipped_write(struct f2fs_sb_info *sbi,
+ struct writeback_control *wbc)
+{
+ long skipped = wbc->pages_skipped;
+
+ if (is_sbi_flag_set(sbi, SBI_ENABLE_CHECKPOINT) && skipped &&
+ wbc->sync_mode == WB_SYNC_ALL)
+ atomic_add(skipped, &sbi->nr_pages[F2FS_SKIPPED_WRITE]);
+}
+
static int __f2fs_write_data_pages(struct address_space *mapping,
struct writeback_control *wbc,
enum iostat_type io_type)
@@ -3559,10 +3569,19 @@ static int __f2fs_write_data_pages(struct address_space *mapping,
*/
f2fs_remove_dirty_inode(inode);
+
+ /*
+ * f2fs_write_cache_pages() has retry logic for EAGAIN case which is
+ * common when racing w/ checkpoint, so only update skipped write
+ * when ret is non-zero.
+ */
+ if (ret)
+ update_skipped_write(sbi, wbc);
return ret;
skip_write:
wbc->pages_skipped += get_dirty_pages(inode);
+ update_skipped_write(sbi, wbc);
trace_f2fs_writepages(mapping->host, wbc, DATA);
return 0;
}
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 035239758e33..52cec6b3ecf0 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1238,6 +1238,7 @@ enum count_type {
F2FS_RD_META,
F2FS_DIO_WRITE,
F2FS_DIO_READ,
+ F2FS_SKIPPED_WRITE, /* skip or fail during f2fs_enable_checkpoint() */
NR_COUNT_TYPE,
};
@@ -1476,6 +1477,7 @@ enum {
SBI_IS_RESIZEFS, /* resizefs is in process */
SBI_IS_FREEZING, /* freezefs is in process */
SBI_IS_WRITABLE, /* remove ro mountoption transiently */
+ SBI_ENABLE_CHECKPOINT, /* indicate it's during f2fs_enable_checkpoint() */
MAX_SBI_FLAG,
};
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 97c2264ec7fe..0afe9f829058 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -2690,6 +2690,7 @@ static int f2fs_enable_checkpoint(struct f2fs_sb_info *sbi)
long long start, writeback, end;
int ret;
struct f2fs_lock_context lc;
+ long long skipped_write, dirty_data;
f2fs_info(sbi, "f2fs_enable_checkpoint() starts, meta: %lld, node: %lld, data: %lld",
get_pages(sbi, F2FS_DIRTY_META),
@@ -2698,17 +2699,45 @@ static int f2fs_enable_checkpoint(struct f2fs_sb_info *sbi)
start = ktime_get();
+ set_sbi_flag(sbi, SBI_ENABLE_CHECKPOINT);
+
/* we should flush all the data to keep data consistency */
do {
+ skipped_write = get_pages(sbi, F2FS_SKIPPED_WRITE);
+ dirty_data = get_pages(sbi, F2FS_DIRTY_DATA);
+
sync_inodes_sb(sbi->sb);
f2fs_io_schedule_timeout(DEFAULT_SCHEDULE_TIMEOUT);
- } while (get_pages(sbi, F2FS_DIRTY_DATA) && retry--);
+
+ f2fs_info(sbi, "sync_inode_sb done, dirty_data: %lld, %lld, "
+ "skipped write: %lld, %lld, retry: %d",
+ get_pages(sbi, F2FS_DIRTY_DATA),
+ dirty_data,
+ get_pages(sbi, F2FS_SKIPPED_WRITE),
+ skipped_write, retry);
+
+ /*
+ * sync_inodes_sb() has retry logic, so let's check dirty_data
+ * in prior to skipped_write in case there is no dirty data.
+ */
+ if (!get_pages(sbi, F2FS_DIRTY_DATA))
+ break;
+ if (get_pages(sbi, F2FS_SKIPPED_WRITE) == skipped_write)
+ break;
+ } while (retry--);
+
+ clear_sbi_flag(sbi, SBI_ENABLE_CHECKPOINT);
writeback = ktime_get();
- if (unlikely(get_pages(sbi, F2FS_DIRTY_DATA)))
- f2fs_warn(sbi, "checkpoint=enable has some unwritten data: %lld",
- get_pages(sbi, F2FS_DIRTY_DATA));
+ if (unlikely(get_pages(sbi, F2FS_DIRTY_DATA) ||
+ get_pages(sbi, F2FS_SKIPPED_WRITE)))
+ f2fs_warn(sbi, "checkpoint=enable unwritten data: %lld, skipped data: %lld, retry: %d",
+ get_pages(sbi, F2FS_DIRTY_DATA),
+ get_pages(sbi, F2FS_SKIPPED_WRITE), retry);
+
+ if (get_pages(sbi, F2FS_SKIPPED_WRITE))
+ atomic_set(&sbi->nr_pages[F2FS_SKIPPED_WRITE], 0);
f2fs_down_write_trace(&sbi->gc_lock, &lc);
f2fs_dirty_to_prefree(sbi);
--
2.40.1
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