2023-04-17 12:38:57

by Pankaj Raghav

Subject: [PATCH 2/4] buffer: add folio_alloc_buffers() helper

Folio version of alloc_page_buffers() helper. This is required to convert
create_page_buffers() to folio_create_buffers() later in the series.

alloc_page_buffers() has been modified to call folio_alloc_buffers()
which adds one call to compound_head() but folio_alloc_buffers() removes
one call to compound_head() compared to the existing alloc_page_buffers()
implementation.

Signed-off-by: Pankaj Raghav <[email protected]>
---
fs/buffer.c | 23 +++++++++++++++--------
include/linux/buffer_head.h | 2 ++
2 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index 7e74bd77a81b..75415170e286 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -842,7 +842,7 @@ int remove_inode_buffers(struct inode *inode)
}

/*
- * Create the appropriate buffers when given a page for data area and
+ * Create the appropriate buffers when given a folio for data area and
* the size of each buffer.. Use the bh->b_this_page linked list to
* follow the buffers created. Return NULL if unable to create more
* buffers.
@@ -850,8 +850,8 @@ int remove_inode_buffers(struct inode *inode)
* The retry flag is used to differentiate async IO (paging, swapping)
* which may not fail from ordinary buffer allocations.
*/
-struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
- bool retry)
+struct buffer_head *folio_alloc_buffers(struct folio *folio, unsigned long size,
+ bool retry)
{
struct buffer_head *bh, *head;
gfp_t gfp = GFP_NOFS | __GFP_ACCOUNT;
@@ -861,12 +861,12 @@ struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
if (retry)
gfp |= __GFP_NOFAIL;

- /* The page lock pins the memcg */
- memcg = page_memcg(page);
+ /* The folio lock pins the memcg */
+ memcg = folio_memcg(folio);
old_memcg = set_active_memcg(memcg);

head = NULL;
- offset = PAGE_SIZE;
+ offset = folio_size(folio);
while ((offset -= size) >= 0) {
bh = alloc_buffer_head(gfp);
if (!bh)
@@ -878,8 +878,8 @@ struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,

bh->b_size = size;

- /* Link the buffer to its page */
- set_bh_page(bh, page, offset);
+ /* Link the buffer to its folio */
+ folio_set_bh(bh, folio, offset);
}
out:
set_active_memcg(old_memcg);
@@ -898,6 +898,13 @@ struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,

goto out;
}
+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);
+}
EXPORT_SYMBOL_GPL(alloc_page_buffers);

static inline void
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index 7e92d23f4782..0b14eab41bd1 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -199,6 +199,8 @@ void set_bh_page(struct buffer_head *bh,
void folio_set_bh(struct buffer_head *bh, struct folio *folio,
unsigned long offset);
bool try_to_free_buffers(struct folio *);
+struct buffer_head *folio_alloc_buffers(struct folio *folio, unsigned long size,
+ bool retry);
struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
bool retry);
void create_empty_buffers(struct page *, unsigned long,
--
2.34.1

2023-04-17 13:35:31

by Matthew Wilcox

Subject: Re: [PATCH 2/4] buffer: add folio_alloc_buffers() helper

On Mon, Apr 17, 2023 at 02:36:16PM +0200, Pankaj Raghav wrote:
> Folio version of alloc_page_buffers() helper. This is required to convert
> create_page_buffers() to folio_create_buffers() later in the series.
>
> alloc_page_buffers() has been modified to call folio_alloc_buffers()
> which adds one call to compound_head() but folio_alloc_buffers() removes
> one call to compound_head() compared to the existing alloc_page_buffers()
> implementation.
>
> Signed-off-by: Pankaj Raghav <[email protected]>

Reviewed-by: Matthew Wilcox (Oracle) <[email protected]>

2023-04-17 14:05:11

by Hannes Reinecke

Subject: Re: [PATCH 2/4] buffer: add folio_alloc_buffers() helper

On 4/17/23 14:36, Pankaj Raghav wrote:
> Folio version of alloc_page_buffers() helper. This is required to convert
> create_page_buffers() to folio_create_buffers() later in the series.
>
> alloc_page_buffers() has been modified to call folio_alloc_buffers()
> which adds one call to compound_head() but folio_alloc_buffers() removes
> one call to compound_head() compared to the existing alloc_page_buffers()
> implementation.
>
> Signed-off-by: Pankaj Raghav <[email protected]>
> ---
> fs/buffer.c | 23 +++++++++++++++--------
> include/linux/buffer_head.h | 2 ++
> 2 files changed, 17 insertions(+), 8 deletions(-)
>
Reviewed-by: Hannes Reinecke <[email protected]>

Cheers,

Hannes