buffer: pass GFP flags to folio_alloc_buffers()

Patch series "Add and use bdev_getblk()", v2.

This patch series fixes a bug reported by Hui Zhu; see proposed
patches v1 and v2:
https://lore.kernel.org/linux-fsdevel/20230811035705.3296-1-teawaterz@linux.alibaba.com/
https://lore.kernel.org/linux-fsdevel/20230811071519.1094-1-teawaterz@linux.alibaba.com/

I decided to go in a rather different direction for this fix, and fix a
related problem at the same time.  I don't think there's any urgency to
rush this into Linus' tree, nor have I marked it for stable.  Reasonable
people may disagree.


This patch (of 8):

Instead of creating entirely new flags, inherit them from grow_dev_page().
The other callers create the same flags that this function used to
create.

Link: https://lkml.kernel.org/r/20230914150011.843330-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20230914150011.843330-2-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Hui Zhu <teawater@antgroup.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fs/buffer.c

@@ -915,16 +915,12 @@ int remove_inode_buffers(struct inode *inode)
  * which may not fail from ordinary buffer allocations.
  */
 struct buffer_head *folio_alloc_buffers(struct folio *folio, unsigned long size,
-					bool retry)
+					gfp_t gfp)
 {
 	struct buffer_head *bh, *head;
-	gfp_t gfp = GFP_NOFS | __GFP_ACCOUNT;
 	long offset;
 	struct mem_cgroup *memcg, *old_memcg;
 
-	if (retry)
-		gfp |= __GFP_NOFAIL;
-
 	/* The folio lock pins the memcg */
 	memcg = folio_memcg(folio);
 	old_memcg = set_active_memcg(memcg);
@@ -967,7 +963,11 @@ EXPORT_SYMBOL_GPL(folio_alloc_buffers);
 struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
 				       bool retry)
 {
-	return folio_alloc_buffers(page_folio(page), size, retry);
+	gfp_t gfp = GFP_NOFS | __GFP_ACCOUNT;
+	if (retry)
+		gfp |= __GFP_NOFAIL;
+
+	return folio_alloc_buffers(page_folio(page), size, gfp);
 }
 EXPORT_SYMBOL_GPL(alloc_page_buffers);
 
@@ -1069,7 +1069,7 @@ grow_dev_page(struct block_device *bdev, sector_t block,
 			goto failed;
 	}
 
-	bh = folio_alloc_buffers(folio, size, true);
+	bh = folio_alloc_buffers(folio, size, gfp_mask | __GFP_ACCOUNT);
 
 	/*
 	 * Link the folio to the buffers and initialise them.  Take the
@@ -1644,8 +1644,9 @@ void folio_create_empty_buffers(struct folio *folio, unsigned long blocksize,
 				unsigned long b_state)
 {
 	struct buffer_head *bh, *head, *tail;
+	gfp_t gfp = GFP_NOFS | __GFP_ACCOUNT | __GFP_NOFAIL;
 
-	head = folio_alloc_buffers(folio, blocksize, true);
+	head = folio_alloc_buffers(folio, blocksize, gfp);
 	bh = head;
 	do {
 		bh->b_state |= b_state;

include/linux/buffer_head.h

@@ -198,7 +198,7 @@ void touch_buffer(struct buffer_head *bh);
 void folio_set_bh(struct buffer_head *bh, struct folio *folio,
 		  unsigned long offset);
 struct buffer_head *folio_alloc_buffers(struct folio *folio, unsigned long size,
-					bool retry);
+					gfp_t gfp);
 struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
 		bool retry);
 void create_empty_buffers(struct page *, unsigned long,