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From:   Daeho Jeong <daeho43@gmail.com>
To:     linux-kernel@vger.kernel.org,
        linux-f2fs-devel@lists.sourceforge.net, kernel-team@android.com
Cc:     Daeho Jeong <daehojeong@google.com>
Subject: [PATCH v4 1/2] f2fs: correct i_size change for atomic writes
Date:   Tue,  4 Oct 2022 10:13:50 -0700
Message-Id: <20221004171351.3678194-1-daeho43@gmail.com>
MIME-Version: 1.0
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From: Daeho Jeong <daehojeong@google.com>

We need to make sure i_size doesn't change until atomic write commit is
successful and restore it when commit is failed.

Signed-off-by: Daeho Jeong <daehojeong@google.com>
---
v4: move i_size update after clearing atomic file flag in
    f2fs_abort_atomic_write()
v3: make sure inode is clean while atomic writing
---
 fs/f2fs/f2fs.h    |  1 +
 fs/f2fs/file.c    | 18 +++++++++++-------
 fs/f2fs/inode.c   |  3 +++
 fs/f2fs/segment.c |  7 +++++--
 4 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index dee7b67a17a6..539da7f12cfc 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -821,6 +821,7 @@ struct f2fs_inode_info {
 	unsigned int i_cluster_size;		/* cluster size */
 
 	unsigned int atomic_write_cnt;
+	loff_t original_i_size;		/* original i_size before atomic write */
 };
 
 static inline void get_extent_info(struct extent_info *ext,
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 5efe0e4a725a..ce2336d2f688 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -1989,6 +1989,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
 	struct f2fs_inode_info *fi = F2FS_I(inode);
 	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
 	struct inode *pinode;
+	loff_t isize;
 	int ret;
 
 	if (!inode_owner_or_capable(mnt_userns, inode))
@@ -2047,7 +2048,12 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
 		f2fs_up_write(&fi->i_gc_rwsem[WRITE]);
 		goto out;
 	}
-	f2fs_i_size_write(fi->cow_inode, i_size_read(inode));
+
+	f2fs_write_inode(inode, NULL);
+
+	isize = i_size_read(inode);
+	fi->original_i_size = isize;
+	f2fs_i_size_write(fi->cow_inode, isize);
 
 	spin_lock(&sbi->inode_lock[ATOMIC_FILE]);
 	sbi->atomic_files++;
@@ -2087,16 +2093,14 @@ static int f2fs_ioc_commit_atomic_write(struct file *filp)
 
 	if (f2fs_is_atomic_file(inode)) {
 		ret = f2fs_commit_atomic_write(inode);
-		if (ret)
-			goto unlock_out;
-
-		ret = f2fs_do_sync_file(filp, 0, LLONG_MAX, 0, true);
 		if (!ret)
-			f2fs_abort_atomic_write(inode, false);
+			ret = f2fs_do_sync_file(filp, 0, LLONG_MAX, 0, true);
+
+		f2fs_abort_atomic_write(inode, ret);
 	} else {
 		ret = f2fs_do_sync_file(filp, 0, LLONG_MAX, 1, false);
 	}
-unlock_out:
+
 	inode_unlock(inode);
 	mnt_drop_write_file(filp);
 	return ret;
diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
index cde0a3dc80c3..64d7772b4cd9 100644
--- a/fs/f2fs/inode.c
+++ b/fs/f2fs/inode.c
@@ -30,6 +30,9 @@ void f2fs_mark_inode_dirty_sync(struct inode *inode, bool sync)
 	if (f2fs_inode_dirtied(inode, sync))
 		return;
 
+	if (f2fs_is_atomic_file(inode))
+		return;
+
 	mark_inode_dirty_sync(inode);
 }
 
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 460048f3c850..abb55cd418c1 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -193,14 +193,17 @@ void f2fs_abort_atomic_write(struct inode *inode, bool clean)
 	if (!f2fs_is_atomic_file(inode))
 		return;
 
-	if (clean)
-		truncate_inode_pages_final(inode->i_mapping);
 	clear_inode_flag(fi->cow_inode, FI_COW_FILE);
 	iput(fi->cow_inode);
 	fi->cow_inode = NULL;
 	release_atomic_write_cnt(inode);
 	clear_inode_flag(inode, FI_ATOMIC_FILE);
 
+	if (clean) {
+		truncate_inode_pages_final(inode->i_mapping);
+		f2fs_i_size_write(inode, fi->original_i_size);
+	}
+
 	spin_lock(&sbi->inode_lock[ATOMIC_FILE]);
 	sbi->atomic_files--;
 	spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);
-- 
2.38.0.rc1.362.ged0d419d3c-goog