f2fs: remove allow_outplace_dio()

We can just check f2fs_lfs_mode() directly.  The block_unaligned_IO()
check is redundant because in LFS mode, f2fs doesn't do direct I/O
writes that aren't block-aligned (due to f2fs_force_buffered_io()
returning true in this case, triggering the fallback to buffered I/O).
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/data.c

@@ -3553,7 +3553,7 @@ static ssize_t f2fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 	if (f2fs_force_buffered_io(inode, iocb, iter))
 		return 0;
 
-	do_opu = allow_outplace_dio(inode, iocb, iter);
+	do_opu = rw == WRITE && f2fs_lfs_mode(sbi);
 
 	trace_f2fs_direct_IO_enter(inode, offset, count, rw);
 

fs/f2fs/f2fs.h

@@ -4311,16 +4311,6 @@ static inline int block_unaligned_IO(struct inode *inode,
 	return align & blocksize_mask;
 }
 
-static inline int allow_outplace_dio(struct inode *inode,
-				struct kiocb *iocb, struct iov_iter *iter)
-{
-	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
-	int rw = iov_iter_rw(iter);
-
-	return (f2fs_lfs_mode(sbi) && (rw == WRITE) &&
-				!block_unaligned_IO(inode, iocb, iter));
-}
-
 static inline bool f2fs_force_buffered_io(struct inode *inode,
 				struct kiocb *iocb, struct iov_iter *iter)
 {

fs/f2fs/file.c

@@ -4292,7 +4292,7 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 			 * back to buffered IO.
 			 */
 			if (!f2fs_force_buffered_io(inode, iocb, from) &&
-					allow_outplace_dio(inode, iocb, from))
+					f2fs_lfs_mode(F2FS_I_SB(inode)))
 				goto write;
 		}
 		preallocated = true;