+ fs-buffer-add-folio_set_bh-helper.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: fs/buffer: add folio_set_bh helper
has been added to the -mm mm-unstable branch.  Its filename is
     fs-buffer-add-folio_set_bh-helper.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/fs-buffer-add-folio_set_bh-helper.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Pankaj Raghav <p.raghav@samsung.com>
Subject: fs/buffer: add folio_set_bh helper
Date: Mon, 17 Apr 2023 14:36:15 +0200

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/20230417123618.22094-1-p.raghav@samsung.com
Link: https://lkml.kernel.org/r/20230417123618.22094-2-p.raghav@samsung.com
Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/buffer.c                 |   15 +++++++++++++++
 include/linux/buffer_head.h |    2 ++
 2 files changed, 17 insertions(+)

--- a/fs/buffer.c~fs-buffer-add-folio_set_bh-helper
+++ a/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.
  */
--- a/include/linux/buffer_head.h~fs-buffer-add-folio_set_bh-helper
+++ a/include/linux/buffer_head.h
@@ -196,6 +196,8 @@ void mark_buffer_write_io_error(struct b
 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);
_

Patches currently in -mm which might be from p.raghav@samsung.com are

orangefs-use-folios-in-orangefs_readahead.patch
mpage-split-submit_bio-and-bio-end_io-handler-for-reads-and-writes.patch
mpage-use-folios-in-bio-end_io-handler.patch
fs-buffer-add-folio_set_bh-helper.patch
buffer-add-folio_alloc_buffers-helper.patch
fs-buffer-add-folio_create_empty_buffers-helper.patch
fs-buffer-convert-create_page_buffers-to-folio_create_buffers.patch