f2fs: change the current atomic write way

Current atomic write has three major issues like below.
 - keeps the updates in non-reclaimable memory space and they are even
   hard to be migrated, which is not good for contiguous memory
   allocation.
 - disk spaces used for atomic files cannot be garbage collected, so
   this makes it difficult for the filesystem to be defragmented.
 - If atomic write operations hit the threshold of either memory usage
   or garbage collection failure count, All the atomic write operations
   will fail immediately.

To resolve the issues, I will keep a COW inode internally for all the
updates to be flushed from memory, when we need to flush them out in a
situation like high memory pressure. These COW inodes will be tagged
as orphan inodes to be reclaimed in case of sudden power-cut or system
failure during atomic writes.

Signed-off-by: Daeho Jeong <daehojeong@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 1 insertions, 5 deletions

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index aa51c30333d3..0900c552a16c 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1339,9 +1339,6 @@ static struct inode *f2fs_alloc_inode(struct super_block *sb)
 	spin_lock_init(&fi->i_size_lock);
 	INIT_LIST_HEAD(&fi->dirty_list);
 	INIT_LIST_HEAD(&fi->gdirty_list);
-	INIT_LIST_HEAD(&fi->inmem_ilist);
-	INIT_LIST_HEAD(&fi->inmem_pages);
-	mutex_init(&fi->inmem_lock);
 	init_f2fs_rwsem(&fi->i_gc_rwsem[READ]);
 	init_f2fs_rwsem(&fi->i_gc_rwsem[WRITE]);
 	init_f2fs_rwsem(&fi->i_xattr_sem);
@@ -1382,9 +1379,8 @@ static int f2fs_drop_inode(struct inode *inode)
 			atomic_inc(&inode->i_count);
 			spin_unlock(&inode->i_lock);
 
-			/* some remained atomic pages should discarded */
 			if (f2fs_is_atomic_file(inode))
-				f2fs_drop_inmem_pages(inode);
+				f2fs_abort_atomic_write(inode, true);
 
 			/* should remain fi->extent_tree for writepage */
 			f2fs_destroy_extent_node(inode);