Btrfs: remove no longer needed range length checks for deduplication

Comparing the content of the pages in the range to deduplicate is now
done in generic_remap_checks called by the generic helper
generic_remap_file_range_prep(), which takes care of ensuring we do not
compare/deduplicate undefined data beyond a file's EOF (range from EOF
to the next block boundary). So remove these checks which are now
redundant.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/ioctl.c

@@ -3242,32 +3242,17 @@ static void btrfs_double_extent_lock(struct inode *inode1, u64 loff1,
 	lock_extent(&BTRFS_I(inode2)->io_tree, loff2, loff2 + len - 1);
 }
 
-static int btrfs_extent_same_range(struct inode *src, u64 loff, u64 olen,
+static int btrfs_extent_same_range(struct inode *src, u64 loff, u64 len,
 				   struct inode *dst, u64 dst_loff)
 {
-	u64 bs = BTRFS_I(src)->root->fs_info->sb->s_blocksize;
 	int ret;
-	u64 len = olen;
-
-	if (loff + len == src->i_size)
-		len = ALIGN(src->i_size, bs) - loff;
-	/*
-	 * For same inode case we don't want our length pushed out past i_size
-	 * as comparing that data range makes no sense.
-	 *
-	 * This effectively means we require aligned extents for the single
-	 * inode case, whereas the other cases allow an unaligned length so long
-	 * as it ends at i_size.
-	 */
-	if (dst == src && len != olen)
-		return -EINVAL;
 
 	/*
 	 * Lock destination range to serialize with concurrent readpages() and
 	 * source range to serialize with relocation.
 	 */
 	btrfs_double_extent_lock(src, loff, dst, dst_loff, len);
-	ret = btrfs_clone(src, dst, loff, olen, len, dst_loff, 1);
+	ret = btrfs_clone(src, dst, loff, len, len, dst_loff, 1);
 	btrfs_double_extent_unlock(src, loff, dst, dst_loff, len);
 
 	return ret;