btrfs: remove mirror_num argument from extent_read_full_page

It's called only from btrfs_readpage which always passes 0 so just sink
the argument into extent_read_full_page.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/extent_io.c

@@ -3381,15 +3381,15 @@ static int __extent_read_full_page(struct page *page, struct bio **bio,
 	return ret;
 }
 
-int extent_read_full_page(struct page *page, int mirror_num)
+int extent_read_full_page(struct page *page)
 {
 	struct bio *bio = NULL;
 	unsigned long bio_flags = 0;
 	int ret;
 
-	ret = __extent_read_full_page(page, &bio, mirror_num, &bio_flags, 0);
+	ret = __extent_read_full_page(page, &bio, 0, &bio_flags, 0);
 	if (bio)
-		ret = submit_one_bio(bio, mirror_num, bio_flags);
+		ret = submit_one_bio(bio, 0, bio_flags);
 	return ret;
 }
 

fs/btrfs/extent_io.h

@@ -193,7 +193,7 @@ typedef struct extent_map *(get_extent_t)(struct btrfs_inode *inode,
 int try_release_extent_mapping(struct page *page, gfp_t mask);
 int try_release_extent_buffer(struct page *page);
 
-int extent_read_full_page(struct page *page, int mirror_num);
+int extent_read_full_page(struct page *page);
 int extent_write_full_page(struct page *page, struct writeback_control *wbc);
 int extent_write_locked_range(struct inode *inode, u64 start, u64 end,
 			      int mode);

fs/btrfs/inode.c

@@ -8040,7 +8040,7 @@ static int btrfs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 
 int btrfs_readpage(struct file *file, struct page *page)
 {
-	return extent_read_full_page(page, 0);
+	return extent_read_full_page(page);
 }
 
 static int btrfs_writepage(struct page *page, struct writeback_control *wbc)