btrfs: remove the submit_extent_page return value

submit_extent_page always returns 0 since commit d5e4377d ("btrfs:
split zone append bios in btrfs_submit_bio").  Change it to a void return
type and remove all the unreachable error handling code in the callers.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/extent_io.c

@@ -1010,9 +1010,9 @@ static void alloc_new_bio(struct btrfs_inode *inode,
  * The mirror number for this IO should already be initizlied in
  * @bio_ctrl->mirror_num.
  */
-static int submit_extent_page(struct btrfs_bio_ctrl *bio_ctrl,
-			      u64 disk_bytenr, struct page *page,
-			      size_t size, unsigned long pg_offset)
+static void submit_extent_page(struct btrfs_bio_ctrl *bio_ctrl,
+			       u64 disk_bytenr, struct page *page,
+			       size_t size, unsigned long pg_offset)
 {
 	struct btrfs_inode *inode = BTRFS_I(page->mapping->host);
 	unsigned int cur = pg_offset;
@@ -1061,7 +1061,6 @@ static int submit_extent_page(struct btrfs_bio_ctrl *bio_ctrl,
 		}
 		cur += added;
 	}
-	return 0;
 }
 
 static int attach_extent_buffer_page(struct extent_buffer *eb,
@@ -1194,7 +1193,7 @@ static int btrfs_do_readpage(struct page *page, struct extent_map **em_cached,
 		unlock_extent(tree, start, end, NULL);
 		btrfs_page_set_error(fs_info, page, start, PAGE_SIZE);
 		unlock_page(page);
-		goto out;
+		return ret;
 	}
 
 	if (page->index == last_byte >> PAGE_SHIFT) {
@@ -1225,8 +1224,7 @@ static int btrfs_do_readpage(struct page *page, struct extent_map **em_cached,
 		if (IS_ERR(em)) {
 			unlock_extent(tree, cur, end, NULL);
 			end_page_read(page, false, cur, end + 1 - cur);
-			ret = PTR_ERR(em);
-			break;
+			return PTR_ERR(em);
 		}
 		extent_offset = cur - em->start;
 		BUG_ON(extent_map_end(em) <= cur);
@@ -1316,22 +1314,13 @@ static int btrfs_do_readpage(struct page *page, struct extent_map **em_cached,
 
 		if (force_bio_submit)
 			submit_one_bio(bio_ctrl);
-		ret = submit_extent_page(bio_ctrl, disk_bytenr, page, iosize,
-					 pg_offset);
-		if (ret) {
-			/*
-			 * We have to unlock the remaining range, or the page
-			 * will never be unlocked.
-			 */
-			unlock_extent(tree, cur, end, NULL);
-			end_page_read(page, false, cur, end + 1 - cur);
-			goto out;
-		}
+		submit_extent_page(bio_ctrl, disk_bytenr, page, iosize,
+				   pg_offset);
 		cur = cur + iosize;
 		pg_offset += iosize;
 	}
-out:
-	return ret;
+
+	return 0;
 }
 
 int btrfs_read_folio(struct file *file, struct folio *folio)
@@ -1622,19 +1611,9 @@ static noinline_for_stack int __extent_writepage_io(struct btrfs_inode *inode,
 		 */
 		btrfs_page_clear_dirty(fs_info, page, cur, iosize);
 
-		ret = submit_extent_page(bio_ctrl, disk_bytenr, page,
-					 iosize, cur - page_offset(page));
-		if (ret) {
-			has_error = true;
-			if (!saved_ret)
-				saved_ret = ret;
-
-			btrfs_page_set_error(fs_info, page, cur, iosize);
-			if (PageWriteback(page))
-				btrfs_page_clear_writeback(fs_info, page, cur,
-							   iosize);
-		}
-
+		submit_extent_page(bio_ctrl, disk_bytenr, page, iosize,
+				   cur - page_offset(page));
+		ret = 0;
 		cur += iosize;
 		nr++;
 	}
@@ -2090,13 +2069,12 @@ static void prepare_eb_write(struct extent_buffer *eb)
  * Unlike the work in write_one_eb(), we rely completely on extent locking.
  * Page locking is only utilized at minimum to keep the VMM code happy.
  */
-static int write_one_subpage_eb(struct extent_buffer *eb,
-				struct btrfs_bio_ctrl *bio_ctrl)
+static void write_one_subpage_eb(struct extent_buffer *eb,
+				 struct btrfs_bio_ctrl *bio_ctrl)
 {
 	struct btrfs_fs_info *fs_info = eb->fs_info;
 	struct page *page = eb->pages[0];
 	bool no_dirty_ebs = false;
-	int ret;
 
 	prepare_eb_write(eb);
 
@@ -2112,17 +2090,8 @@ static int write_one_subpage_eb(struct extent_buffer *eb,
 
 	bio_ctrl->end_io_func = end_bio_subpage_eb_writepage;
 
-	ret = submit_extent_page(bio_ctrl, eb->start, page, eb->len,
-			eb->start - page_offset(page));
-	if (ret) {
-		btrfs_subpage_clear_writeback(fs_info, page, eb->start, eb->len);
-		set_btree_ioerr(page, eb);
-		unlock_page(page);
-
-		if (atomic_dec_and_test(&eb->io_pages))
-			end_extent_buffer_writeback(eb);
-		return -EIO;
-	}
+	submit_extent_page(bio_ctrl, eb->start, page, eb->len,
+			   eb->start - page_offset(page));
 	unlock_page(page);
 	/*
 	 * Submission finished without problem, if no range of the page is
@@ -2130,15 +2099,13 @@ static int write_one_subpage_eb(struct extent_buffer *eb,
 	 */
 	if (no_dirty_ebs)
 		bio_ctrl->wbc->nr_to_write--;
-	return ret;
 }
 
-static noinline_for_stack int write_one_eb(struct extent_buffer *eb,
+static noinline_for_stack void write_one_eb(struct extent_buffer *eb,
 			struct btrfs_bio_ctrl *bio_ctrl)
 {
 	u64 disk_bytenr = eb->start;
 	int i, num_pages;
-	int ret = 0;
 
 	prepare_eb_write(eb);
 
@@ -2150,30 +2117,11 @@ static noinline_for_stack int write_one_eb(struct extent_buffer *eb,
 
 		clear_page_dirty_for_io(p);
 		set_page_writeback(p);
-		ret = submit_extent_page(bio_ctrl, disk_bytenr, p, PAGE_SIZE, 0);
-		if (ret) {
-			set_btree_ioerr(p, eb);
-			if (PageWriteback(p))
-				end_page_writeback(p);
-			if (atomic_sub_and_test(num_pages - i, &eb->io_pages))
-				end_extent_buffer_writeback(eb);
-			ret = -EIO;
-			break;
-		}
+		submit_extent_page(bio_ctrl, disk_bytenr, p, PAGE_SIZE, 0);
 		disk_bytenr += PAGE_SIZE;
 		bio_ctrl->wbc->nr_to_write--;
 		unlock_page(p);
 	}
-
-	if (unlikely(ret)) {
-		for (; i < num_pages; i++) {
-			struct page *p = eb->pages[i];
-			clear_page_dirty_for_io(p);
-			unlock_page(p);
-		}
-	}
-
-	return ret;
 }
 
 /*
@@ -2252,10 +2200,8 @@ static int submit_eb_subpage(struct page *page, struct btrfs_bio_ctrl *bio_ctrl)
 			free_extent_buffer(eb);
 			goto cleanup;
 		}
-		ret = write_one_subpage_eb(eb, bio_ctrl);
+		write_one_subpage_eb(eb, bio_ctrl);
 		free_extent_buffer(eb);
-		if (ret < 0)
-			goto cleanup;
 		submitted++;
 	}
 	return submitted;
@@ -2357,10 +2303,8 @@ static int submit_eb_page(struct page *page, struct btrfs_bio_ctrl *bio_ctrl,
 		btrfs_schedule_zone_finish_bg(cache, eb);
 		btrfs_put_block_group(cache);
 	}
-	ret = write_one_eb(eb, bio_ctrl);
+	write_one_eb(eb, bio_ctrl);
 	free_extent_buffer(eb);
-	if (ret < 0)
-		return ret;
 	return 1;
 }
 
@@ -4381,7 +4325,7 @@ static int read_extent_buffer_subpage(struct extent_buffer *eb, int wait,
 		.mirror_num = mirror_num,
 		.parent_check = check,
 	};
-	int ret = 0;
+	int ret;
 
 	ASSERT(!test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags));
 	ASSERT(PagePrivate(page));
@@ -4399,14 +4343,13 @@ static int read_extent_buffer_subpage(struct extent_buffer *eb, int wait,
 			return ret;
 	}
 
-	ret = 0;
 	if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags) ||
 	    PageUptodate(page) ||
 	    btrfs_subpage_test_uptodate(fs_info, page, eb->start, eb->len)) {
 		set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
 		unlock_extent(io_tree, eb->start, eb->start + eb->len - 1,
 			      &cached_state);
-		return ret;
+		return 0;
 	}
 
 	clear_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags);
@@ -4418,27 +4361,19 @@ static int read_extent_buffer_subpage(struct extent_buffer *eb, int wait,
 	btrfs_subpage_clear_error(fs_info, page, eb->start, eb->len);
 
 	btrfs_subpage_start_reader(fs_info, page, eb->start, eb->len);
-	ret = submit_extent_page(&bio_ctrl, eb->start, page, eb->len,
-				 eb->start - page_offset(page));
-	if (ret) {
-		/*
-		 * In the endio function, if we hit something wrong we will
-		 * increase the io_pages, so here we need to decrease it for
-		 * error path.
-		 */
-		atomic_dec(&eb->io_pages);
-	}
+	submit_extent_page(&bio_ctrl, eb->start, page, eb->len,
+			   eb->start - page_offset(page));
 	submit_one_bio(&bio_ctrl);
-	if (ret || wait != WAIT_COMPLETE) {
+	if (wait != WAIT_COMPLETE) {
 		free_extent_state(cached_state);
-		return ret;
+		return 0;
 	}
 
 	wait_extent_bit(io_tree, eb->start, eb->start + eb->len - 1,
 			EXTENT_LOCKED, &cached_state);
 	if (!test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags))
-		ret = -EIO;
-	return ret;
+		return -EIO;
+	return 0;
 }
 
 int read_extent_buffer_pages(struct extent_buffer *eb, int wait, int mirror_num,
@@ -4446,8 +4381,6 @@ int read_extent_buffer_pages(struct extent_buffer *eb, int wait, int mirror_num,
 {
 	int i;
 	struct page *page;
-	int err;
-	int ret = 0;
 	int locked_pages = 0;
 	int all_uptodate = 1;
 	int num_pages;
@@ -4521,27 +4454,9 @@ int read_extent_buffer_pages(struct extent_buffer *eb, int wait, int mirror_num,
 		page = eb->pages[i];
 
 		if (!PageUptodate(page)) {
-			if (ret) {
-				atomic_dec(&eb->io_pages);
-				unlock_page(page);
-				continue;
-			}
-
 			ClearPageError(page);
-			err = submit_extent_page(&bio_ctrl,
-						 page_offset(page), page,
-						 PAGE_SIZE, 0);
-			if (err) {
-				/*
-				 * We failed to submit the bio so it's the
-				 * caller's responsibility to perform cleanup
-				 * i.e unlock page/set error bit.
-				 */
-				ret = err;
-				SetPageError(page);
-				unlock_page(page);
-				atomic_dec(&eb->io_pages);
-			}
+			submit_extent_page(&bio_ctrl, page_offset(page), page,
+					   PAGE_SIZE, 0);
 		} else {
 			unlock_page(page);
 		}
@@ -4549,17 +4464,17 @@ int read_extent_buffer_pages(struct extent_buffer *eb, int wait, int mirror_num,
 
 	submit_one_bio(&bio_ctrl);
 
-	if (ret || wait != WAIT_COMPLETE)
-		return ret;
+	if (wait != WAIT_COMPLETE)
+		return 0;
 
 	for (i = 0; i < num_pages; i++) {
 		page = eb->pages[i];
 		wait_on_page_locked(page);
 		if (!PageUptodate(page))
-			ret = -EIO;
+			return -EIO;
 	}
 
-	return ret;
+	return 0;
 
 unlock_exit:
 	while (locked_pages > 0) {
@@ -4567,7 +4482,7 @@ int read_extent_buffer_pages(struct extent_buffer *eb, int wait, int mirror_num,
 		page = eb->pages[locked_pages];
 		unlock_page(page);
 	}
-	return ret;
+	return 0;
 }
 
 static bool report_eb_range(const struct extent_buffer *eb, unsigned long start,