fs/buffer: add folio_set_bh helper

Patch series "convert create_page_buffers to folio_create_buffers". One of the first kernel panic we hit when we try to increase the block size > 4k is inside create_page_buffers()[1]. Even though buffer.c function do not support large folios (folios > PAGE_SIZE) at the moment, these changes are required when we want to remove that constraint. This patch (of 4): The folio version of set_bh_page(). This is required to convert create_page_buffers() to folio_create_buffers() later in the series. Link: https://lkml.kernel.org/r/[email protected] Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Pankaj Raghav <[email protected]> Reviewed-by: Matthew Wilcox (Oracle) <[email protected]> Reviewed-by: Hannes Reinecke <[email protected]> Cc: Alexander Viro <[email protected]> Cc: Christian Brauner <[email protected]> Cc: Luis Chamberlain <[email protected]> Signed-off-by: Andrew Morton <[email protected]>
kawasaki · Apr 21, 2023 · 465e5e6 · 465e5e6
1 parent 760aee0
commit 465e5e6
Show file tree

Hide file tree

Showing 2 changed files with 17 additions and 0 deletions.
diff --git a/fs/buffer.c b/fs/buffer.c
@@ -1485,6 +1485,21 @@ void set_bh_page(struct buffer_head *bh,
 }
 EXPORT_SYMBOL(set_bh_page);
 
+void folio_set_bh(struct buffer_head *bh, struct folio *folio,
+		  unsigned long offset)
+{
+	bh->b_folio = folio;
+	BUG_ON(offset >= folio_size(folio));
+	if (folio_test_highmem(folio))
+		/*
+		 * This catches illegal uses and preserves the offset:
+		 */
+		bh->b_data = (char *)(0 + offset);
+	else
+		bh->b_data = folio_address(folio) + offset;
+}
+EXPORT_SYMBOL(folio_set_bh);
+
 /*
  * Called when truncating a buffer on a page completely.
  */

diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
@@ -196,6 +196,8 @@ void mark_buffer_write_io_error(struct buffer_head *bh);
 void touch_buffer(struct buffer_head *bh);
 void set_bh_page(struct buffer_head *bh,
 		struct page *page, unsigned long offset);
+void folio_set_bh(struct buffer_head *bh, struct folio *folio,
+		  unsigned long offset);
 bool try_to_free_buffers(struct folio *);
 struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
 		bool retry);