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, 2 deletions

diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
index 02630c17da93..2fce8fa0dac8 100644
--- a/fs/f2fs/inode.c
+++ b/fs/f2fs/inode.c
@@ -745,9 +745,8 @@ void f2fs_evict_inode(struct inode *inode)
 	nid_t xnid = F2FS_I(inode)->i_xattr_nid;
 	int err = 0;
 
-	/* some remained atomic pages should discarded */
 	if (f2fs_is_atomic_file(inode))
-		f2fs_drop_inmem_pages(inode);
+		f2fs_abort_atomic_write(inode, true);
 
 	trace_f2fs_evict_inode(inode);
 	truncate_inode_pages_final(&inode->i_data);