btrfs: remove trivial wrapper btrfs_force_ra

It's a simple call page_cache_sync_readahead, same arguments in the same
order.
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/ctree.h

@@ -3136,14 +3136,6 @@ noinline int can_nocow_extent(struct inode *inode, u64 offset, u64 *len,
 			      u64 *orig_start, u64 *orig_block_len,
 			      u64 *ram_bytes);
 
-/* This forces readahead on a given range of bytes in an inode */
-static inline void btrfs_force_ra(struct address_space *mapping,
-				  struct file_ra_state *ra, struct file *file,
-				  pgoff_t offset, unsigned long req_size)
-{
-	page_cache_sync_readahead(mapping, ra, file, offset, req_size);
-}
-
 struct inode *btrfs_lookup_dentry(struct inode *dir, struct dentry *dentry);
 int btrfs_set_inode_index(struct btrfs_inode *dir, u64 *index);
 int btrfs_unlink_inode(struct btrfs_trans_handle *trans,

fs/btrfs/ioctl.c

@@ -1364,8 +1364,8 @@ int btrfs_defrag_file(struct inode *inode, struct file *file,
 		if (i + cluster > ra_index) {
 			ra_index = max(i, ra_index);
 			if (ra)
-				btrfs_force_ra(inode->i_mapping, ra, file,
-						ra_index, cluster);
+				page_cache_sync_readahead(inode->i_mapping, ra,
+						file, ra_index, cluster);
 			ra_index += cluster;
 		}
 

fs/btrfs/send.c

@@ -4733,7 +4733,7 @@ static ssize_t fill_read_buf(struct send_ctx *sctx, u64 offset, u32 len)
 	/* initial readahead */
 	memset(&sctx->ra, 0, sizeof(struct file_ra_state));
 	file_ra_state_init(&sctx->ra, inode->i_mapping);
-	btrfs_force_ra(inode->i_mapping, &sctx->ra, NULL, index,
+	page_cache_sync_readahead(inode->i_mapping, &sctx->ra, NULL, index,
 		       last_index - index + 1);
 
 	while (index <= last_index) {