f2fs: correct i_size change for atomic writes

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>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/f2fs.h

@@ -768,6 +768,7 @@ enum {
 	FI_COMPRESS_RELEASED,	/* compressed blocks were released */
 	FI_ALIGNED_WRITE,	/* enable aligned write */
 	FI_COW_FILE,		/* indicate COW file */
+	FI_ATOMIC_COMMITTED,	/* indicate atomic commit completed except disk sync */
 	FI_MAX,			/* max flag, never be used */
 };
 
@@ -826,6 +827,7 @@ 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,
@@ -3075,6 +3077,8 @@ static inline void f2fs_i_blocks_write(struct inode *inode,
 		set_inode_flag(inode, FI_AUTO_RECOVER);
 }
 
+static inline bool f2fs_is_atomic_file(struct inode *inode);
+
 static inline void f2fs_i_size_write(struct inode *inode, loff_t i_size)
 {
 	bool clean = !is_inode_flag_set(inode, FI_DIRTY_INODE);
@@ -3084,6 +3088,10 @@ static inline void f2fs_i_size_write(struct inode *inode, loff_t i_size)
 		return;
 
 	i_size_write(inode, i_size);
+
+	if (f2fs_is_atomic_file(inode))
+		return;
+
 	f2fs_mark_inode_dirty_sync(inode, true);
 	if (clean || recover)
 		set_inode_flag(inode, FI_AUTO_RECOVER);

fs/f2fs/file.c

@@ -2041,6 +2041,7 @@ 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))
@@ -2099,7 +2100,12 @@ 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);
 
 	stat_inc_atomic_inode(inode);
 
@@ -2137,16 +2143,14 @@ 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;

fs/f2fs/inode.c

@@ -621,9 +621,12 @@ void f2fs_update_inode(struct inode *inode, struct page *node_page)
 	ri->i_uid = cpu_to_le32(i_uid_read(inode));
 	ri->i_gid = cpu_to_le32(i_gid_read(inode));
 	ri->i_links = cpu_to_le32(inode->i_nlink);
-	ri->i_size = cpu_to_le64(i_size_read(inode));
 	ri->i_blocks = cpu_to_le64(SECTOR_TO_BLOCK(inode->i_blocks) + 1);
 
+	if (!f2fs_is_atomic_file(inode) ||
+			is_inode_flag_set(inode, FI_ATOMIC_COMMITTED))
+		ri->i_size = cpu_to_le64(i_size_read(inode));
+
 	if (et) {
 		read_lock(&et->lock);
 		set_raw_extent(&et->largest, &ri->i_ext);

fs/f2fs/segment.c

@@ -192,14 +192,18 @@ 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_COMMITTED);
 	clear_inode_flag(inode, FI_ATOMIC_FILE);
 	stat_dec_atomic_inode(inode);
+
+	if (clean) {
+		truncate_inode_pages_final(inode->i_mapping);
+		f2fs_i_size_write(inode, fi->original_i_size);
+	}
 }
 
 static int __replace_atomic_write_block(struct inode *inode, pgoff_t index,
@@ -335,10 +339,12 @@ static int __f2fs_commit_atomic_write(struct inode *inode)
 	}
 
 out:
-	if (ret)
+	if (ret) {
 		sbi->revoked_atomic_block += fi->atomic_write_cnt;
-	else
+	} else {
 		sbi->committed_atomic_block += fi->atomic_write_cnt;
+		set_inode_flag(inode, FI_ATOMIC_COMMITTED);
+	}
 
 	__complete_revoke_list(inode, &revoke_list, ret ? true : false);