f2fs: use meta inode for GC of COW file

commit f18d0076933689775fe7faeeb10ee93ff01be6ab upstream.

In case of the COW file, new updates and GC writes are already
separated to page caches of the atomic file and COW file. As some cases
that use the meta inode for GC, there are some race issues between a
foreground thread and GC thread.

To handle them, we need to take care when to invalidate and wait
writeback of GC pages in COW files as the case of using the meta inode.
Also, a pointer from the COW inode to the original inode is required to
check the state of original pages.

For the former, we can solve the problem by using the meta inode for GC
of COW files. Then let's get a page from the original inode in
move_data_block when GCing the COW file to avoid race condition.

Fixes: 3db1de0e582c ("f2fs: change the current atomic write way")
Cc: stable@vger.kernel.org #v5.19+
Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
Reviewed-by: Yeongjin Gil <youngjin.gil@samsung.com>
Signed-off-by: Sunmin Jeong <s_min.jeong@samsung.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

6 files changed, 23 insertions, 7 deletions

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 6dd60b406243..03bfba48b1cf 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -2601,7 +2601,7 @@ bool f2fs_should_update_outplace(struct inode *inode, struct f2fs_io_info *fio)
 		return true;
 	if (IS_NOQUOTA(inode))
 		return true;
-	if (f2fs_is_atomic_file(inode))
+	if (f2fs_used_in_atomic_write(inode))
 		return true;
 	/* rewrite low ratio compress data w/ OPU mode to avoid fragmentation */
 	if (f2fs_compressed_file(inode) &&
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 9c2525a5d10e..7a73bc38c0a5 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -842,7 +842,11 @@ struct f2fs_inode_info {
 	struct task_struct *atomic_write_task;	/* store atomic write task */
 	struct extent_tree *extent_tree[NR_EXTENT_CACHES];
 					/* cached extent_tree entry */
-	struct inode *cow_inode;	/* copy-on-write inode for atomic write */
+	union {
+		struct inode *cow_inode;	/* copy-on-write inode for atomic write */
+		struct inode *atomic_inode;
+					/* point to atomic_inode, available only for cow_inode */
+	};
 
 	/* avoid racing between foreground op and gc */
 	struct f2fs_rwsem i_gc_rwsem[2];
@@ -4261,9 +4265,14 @@ static inline bool f2fs_post_read_required(struct inode *inode)
 		f2fs_compressed_file(inode);
 }
 
+static inline bool f2fs_used_in_atomic_write(struct inode *inode)
+{
+	return f2fs_is_atomic_file(inode) || f2fs_is_cow_file(inode);
+}
+
 static inline bool f2fs_meta_inode_gc_required(struct inode *inode)
 {
-	return f2fs_post_read_required(inode) || f2fs_is_atomic_file(inode);
+	return f2fs_post_read_required(inode) || f2fs_used_in_atomic_write(inode);
 }
 
 /*
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 0cbaeb97c7f5..485d72ff0522 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -2143,6 +2143,9 @@ static int f2fs_ioc_start_atomic_write(struct file *filp, bool truncate)
 
 		set_inode_flag(fi->cow_inode, FI_COW_FILE);
 		clear_inode_flag(fi->cow_inode, FI_INLINE_DATA);
+
+		/* Set the COW inode's atomic_inode to the atomic inode */
+		F2FS_I(fi->cow_inode)->atomic_inode = inode;
 	} else {
 		/* Reuse the already created COW inode */
 		ret = f2fs_do_truncate_blocks(fi->cow_inode, 0, true);
diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 7ae9257a3ca4..b2951cd930d8 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -1171,7 +1171,8 @@ static bool is_alive(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
 static int ra_data_block(struct inode *inode, pgoff_t index)
 {
 	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
-	struct address_space *mapping = inode->i_mapping;
+	struct address_space *mapping = f2fs_is_cow_file(inode) ?
+				F2FS_I(inode)->atomic_inode->i_mapping : inode->i_mapping;
 	struct dnode_of_data dn;
 	struct page *page;
 	struct f2fs_io_info fio = {
@@ -1260,6 +1261,8 @@ put_page:
 static int move_data_block(struct inode *inode, block_t bidx,
 				int gc_type, unsigned int segno, int off)
 {
+	struct address_space *mapping = f2fs_is_cow_file(inode) ?
+				F2FS_I(inode)->atomic_inode->i_mapping : inode->i_mapping;
 	struct f2fs_io_info fio = {
 		.sbi = F2FS_I_SB(inode),
 		.ino = inode->i_ino,
@@ -1282,7 +1285,7 @@ static int move_data_block(struct inode *inode, block_t bidx,
 				CURSEG_ALL_DATA_ATGC : CURSEG_COLD_DATA;
 
 	/* do not read out */
-	page = f2fs_grab_cache_page(inode->i_mapping, bidx, false);
+	page = f2fs_grab_cache_page(mapping, bidx, false);
 	if (!page)
 		return -ENOMEM;
 
diff --git a/fs/f2fs/inline.c b/fs/f2fs/inline.c
index 46ccd614853b..215daa71dc18 100644
--- a/fs/f2fs/inline.c
+++ b/fs/f2fs/inline.c
@@ -16,7 +16,7 @@
 
 static bool support_inline_data(struct inode *inode)
 {
-	if (f2fs_is_atomic_file(inode))
+	if (f2fs_used_in_atomic_write(inode))
 		return false;
 	if (!S_ISREG(inode->i_mode) && !S_ISLNK(inode->i_mode))
 		return false;
diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
index 755d4268013c..a8ca54ba4349 100644
--- a/fs/f2fs/inode.c
+++ b/fs/f2fs/inode.c
@@ -816,8 +816,9 @@ void f2fs_evict_inode(struct inode *inode)
 
 	f2fs_abort_atomic_write(inode, true);
 
-	if (fi->cow_inode) {
+	if (fi->cow_inode && f2fs_is_cow_file(fi->cow_inode)) {
 		clear_inode_flag(fi->cow_inode, FI_COW_FILE);
+		F2FS_I(fi->cow_inode)->atomic_inode = NULL;
 		iput(fi->cow_inode);
 		fi->cow_inode = NULL;
 	}