linux-kernel - [PATCH v2] f2fs: wait IO writeback in commit_inmem

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Date:   Mon, 23 Apr 2018 23:14:25 +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 <yuchao0@...wei.com>
Subject: [PATCH v2] f2fs: wait IO writeback in commit_inmem_pages()

From: Chao Yu <yuchao0@...wei.com>

Thread A				Thread B
- f2fs_ioc_commit_atomic_write
 - commit_inmem_pages
  - f2fs_submit_merged_write_cond
  : write data
					- write_checkpoint
					 - do_checkpoint
					 : commit all node within CP
					 -> SPO
  - f2fs_do_sync_file
   - file_write_and_wait_range
   : wait data writeback

In above race condition, data/node can be flushed in reversed order when
coming a checkpoint before f2fs_do_sync_file, after SPOR, it results in
atomic written data being corrupted.

This patch adds filemap_fdatawait() in commit_inmem_pages() to keep data
and node of atomic file being flushed orderly.

Signed-off-by: Chao Yu <yuchao0@...wei.com>
---
v2:
- clean up codes suggested by Jaegeuk.
 fs/f2fs/file.c    | 4 ++++
 fs/f2fs/segment.c | 2 ++
 2 files changed, 6 insertions(+)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index bac059474342..0cfa65c21d3f 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -217,6 +217,9 @@ static int f2fs_do_sync_file(struct file *file, loff_t start, loff_t end,
 
 	trace_f2fs_sync_file_enter(inode);
 
+	if (atomic)
+		goto write_done;
+
 	/* if fdatasync is triggered, let's do in-place-update */
 	if (datasync || get_dirty_pages(inode) <= SM_I(sbi)->min_fsync_blocks)
 		set_inode_flag(inode, FI_NEED_IPU);
@@ -228,6 +231,7 @@ static int f2fs_do_sync_file(struct file *file, loff_t start, loff_t end,
 		return ret;
 	}
 
+write_done:
 	/* if the inode is dirty, let's recover all the time */
 	if (!f2fs_skip_inode_update(inode, datasync)) {
 		f2fs_write_inode(inode, NULL);
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 710d817c4350..31336fc54d8e 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -419,6 +419,8 @@ static int __commit_inmem_pages(struct inode *inode)
 		__revoke_inmem_pages(inode, &fi->inmem_pages, true, false);
 	} else {
 		__revoke_inmem_pages(inode, &revoke_list, false, false);
+
+		err = filemap_fdatawait(inode->i_mapping);
 	}
 
 	return err;
-- 
2.16.2.17.g38e79b1fd