[PATCH] cramfs: convert cramfs_blkdev_read() to use folios

[PATCH] cramfs: convert cramfs_blkdev_read() to use folios

[Tal Zussman]

Read the block device pages through read_mapping_folio() and copy with
memcpy_from_folio() instead of going through a page.

Signed-off-by: Tal Zussman <tz2294@columbia.edu>
---
 fs/cramfs/inode.c | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c
index d4cd03f4f60d..b55eb3bd29c1 100644
--- a/fs/cramfs/inode.c
+++ b/fs/cramfs/inode.c
@@ -194,7 +194,7 @@ static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset,
 {
 	struct address_space *mapping = sb->s_bdev->bd_mapping;
 	struct file_ra_state ra = {};
-	struct page *pages[BLKS_PER_BUF];
+	struct folio *folios[BLKS_PER_BUF];
 	unsigned i, blocknr, buffer;
 	unsigned long devsize;
 	char *data;
@@ -227,15 +227,15 @@ static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset,
 	page_cache_sync_readahead(mapping, &ra, NULL, blocknr, BLKS_PER_BUF);
 
 	for (i = 0; i < BLKS_PER_BUF; i++) {
-		struct page *page = NULL;
+		struct folio *folio = NULL;
 
 		if (blocknr + i < devsize) {
-			page = read_mapping_page(mapping, blocknr + i, NULL);
+			folio = read_mapping_folio(mapping, blocknr + i, NULL);
 			/* synchronous error? */
-			if (IS_ERR(page))
-				page = NULL;
+			if (IS_ERR(folio))
+				folio = NULL;
 		}
-		pages[i] = page;
+		folios[i] = folio;
 	}
 
 	buffer = next_buffer;
@@ -245,11 +245,14 @@ static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset,
 
 	data = read_buffers[buffer];
 	for (i = 0; i < BLKS_PER_BUF; i++) {
-		struct page *page = pages[i];
+		struct folio *folio = folios[i];
 
-		if (page) {
-			memcpy_from_page(data, page, 0, PAGE_SIZE);
-			put_page(page);
+		if (folio) {
+			size_t offset = offset_in_folio(folio,
+					(loff_t)(blocknr + i) << PAGE_SHIFT);
+
+			memcpy_from_folio(data, folio, offset, PAGE_SIZE);
+			folio_put(folio);
 		} else
 			memset(data, 0, PAGE_SIZE);
 		data += PAGE_SIZE;

---
base-commit: df2908090cda368b01ff43709f51890076c56157
change-id: 20260906-cramfs-blkdev-read-folio-16fecf6908ac

Best regards,
--  
Tal Zussman <tz2294@columbia.edu>

Re: [PATCH] cramfs: convert cramfs_blkdev_read() to use folios

[Tal Zussman]

On 9/6/26 7:45 PM, Tal Zussman wrote:
> Read the block device pages through read_mapping_folio() and copy with
> memcpy_from_folio() instead of going through a page.
> 
> Signed-off-by: Tal Zussman <tz2294@columbia.edu>
> ---
>  fs/cramfs/inode.c | 23 +++++++++++++----------
>  1 file changed, 13 insertions(+), 10 deletions(-)
> 

Following up on this - I don't see a cramfs tree, so could this go
through vfs if everything looks ok? It gets us one step closer to
removing read_mapping_page().

Thanks,
Tal

> diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c
> index d4cd03f4f60d..b55eb3bd29c1 100644
> --- a/fs/cramfs/inode.c
> +++ b/fs/cramfs/inode.c
> @@ -194,7 +194,7 @@ static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset,
>  {
>  	struct address_space *mapping = sb->s_bdev->bd_mapping;
>  	struct file_ra_state ra = {};
> -	struct page *pages[BLKS_PER_BUF];
> +	struct folio *folios[BLKS_PER_BUF];
>  	unsigned i, blocknr, buffer;
>  	unsigned long devsize;
>  	char *data;
> @@ -227,15 +227,15 @@ static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset,
>  	page_cache_sync_readahead(mapping, &ra, NULL, blocknr, BLKS_PER_BUF);
>  
>  	for (i = 0; i < BLKS_PER_BUF; i++) {
> -		struct page *page = NULL;
> +		struct folio *folio = NULL;
>  
>  		if (blocknr + i < devsize) {
> -			page = read_mapping_page(mapping, blocknr + i, NULL);
> +			folio = read_mapping_folio(mapping, blocknr + i, NULL);
>  			/* synchronous error? */
> -			if (IS_ERR(page))
> -				page = NULL;
> +			if (IS_ERR(folio))
> +				folio = NULL;
>  		}
> -		pages[i] = page;
> +		folios[i] = folio;
>  	}
>  
>  	buffer = next_buffer;
> @@ -245,11 +245,14 @@ static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset,
>  
>  	data = read_buffers[buffer];
>  	for (i = 0; i < BLKS_PER_BUF; i++) {
> -		struct page *page = pages[i];
> +		struct folio *folio = folios[i];
>  
> -		if (page) {
> -			memcpy_from_page(data, page, 0, PAGE_SIZE);
> -			put_page(page);
> +		if (folio) {
> +			size_t offset = offset_in_folio(folio,
> +					(loff_t)(blocknr + i) << PAGE_SHIFT);
> +
> +			memcpy_from_folio(data, folio, offset, PAGE_SIZE);
> +			folio_put(folio);
>  		} else
>  			memset(data, 0, PAGE_SIZE);
>  		data += PAGE_SIZE;
> 
> ---
> base-commit: df2908090cda368b01ff43709f51890076c56157
> change-id: 20260906-cramfs-blkdev-read-folio-16fecf6908ac
> 
> Best regards,
> --  
> Tal Zussman <tz2294@columbia.edu>

Re: [PATCH] cramfs: convert cramfs_blkdev_read() to use folios

[Nicolas Pitre]

On Mon, 12 Oct 2026, Tal Zussman wrote:

> On 9/6/26 7:45 PM, Tal Zussman wrote:
> > Read the block device pages through read_mapping_folio() and copy with
> > memcpy_from_folio() instead of going through a page.
> > 
> > Signed-off-by: Tal Zussman <tz2294@columbia.edu>
> > ---
> >  fs/cramfs/inode.c | 23 +++++++++++++----------
> >  1 file changed, 13 insertions(+), 10 deletions(-)
> > 
> 
> Following up on this - I don't see a cramfs tree, so could this go
> through vfs if everything looks ok? It gets us one step closer to
> removing read_mapping_page().
> 
> Thanks,
> Tal

Yes, please forward to the vfs tree.

Acked-by: Nicolas Pitre <nico@fluxnic.net>



> > diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c
> > index d4cd03f4f60d..b55eb3bd29c1 100644
> > --- a/fs/cramfs/inode.c
> > +++ b/fs/cramfs/inode.c
> > @@ -194,7 +194,7 @@ static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset,
> >  {
> >  	struct address_space *mapping = sb->s_bdev->bd_mapping;
> >  	struct file_ra_state ra = {};
> > -	struct page *pages[BLKS_PER_BUF];
> > +	struct folio *folios[BLKS_PER_BUF];
> >  	unsigned i, blocknr, buffer;
> >  	unsigned long devsize;
> >  	char *data;
> > @@ -227,15 +227,15 @@ static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset,
> >  	page_cache_sync_readahead(mapping, &ra, NULL, blocknr, BLKS_PER_BUF);
> >  
> >  	for (i = 0; i < BLKS_PER_BUF; i++) {
> > -		struct page *page = NULL;
> > +		struct folio *folio = NULL;
> >  
> >  		if (blocknr + i < devsize) {
> > -			page = read_mapping_page(mapping, blocknr + i, NULL);
> > +			folio = read_mapping_folio(mapping, blocknr + i, NULL);
> >  			/* synchronous error? */
> > -			if (IS_ERR(page))
> > -				page = NULL;
> > +			if (IS_ERR(folio))
> > +				folio = NULL;
> >  		}
> > -		pages[i] = page;
> > +		folios[i] = folio;
> >  	}
> >  
> >  	buffer = next_buffer;
> > @@ -245,11 +245,14 @@ static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset,
> >  
> >  	data = read_buffers[buffer];
> >  	for (i = 0; i < BLKS_PER_BUF; i++) {
> > -		struct page *page = pages[i];
> > +		struct folio *folio = folios[i];
> >  
> > -		if (page) {
> > -			memcpy_from_page(data, page, 0, PAGE_SIZE);
> > -			put_page(page);
> > +		if (folio) {
> > +			size_t offset = offset_in_folio(folio,
> > +					(loff_t)(blocknr + i) << PAGE_SHIFT);
> > +
> > +			memcpy_from_folio(data, folio, offset, PAGE_SIZE);
> > +			folio_put(folio);
> >  		} else
> >  			memset(data, 0, PAGE_SIZE);
> >  		data += PAGE_SIZE;
> > 
> > ---
> > base-commit: df2908090cda368b01ff43709f51890076c56157
> > change-id: 20260906-cramfs-blkdev-read-folio-16fecf6908ac
> > 
> > Best regards,
> > --  
> > Tal Zussman <tz2294@columbia.edu>
> 
> 

Re: [PATCH] cramfs: convert cramfs_blkdev_read() to use folios

[Tal Zussman]

On 10/12/26 12:16 PM, Nicolas Pitre wrote:
> On Mon, 12 Oct 2026, Tal Zussman wrote:
> 
>> On 9/6/26 7:45 PM, Tal Zussman wrote:
>> > Read the block device pages through read_mapping_folio() and copy with
>> > memcpy_from_folio() instead of going through a page.
>> > 
>> > Signed-off-by: Tal Zussman <tz2294@columbia.edu>
>> > ---
>> >  fs/cramfs/inode.c | 23 +++++++++++++----------
>> >  1 file changed, 13 insertions(+), 10 deletions(-)
>> > 
>> 
>> Following up on this - I don't see a cramfs tree, so could this go
>> through vfs if everything looks ok? It gets us one step closer to
>> removing read_mapping_page().
>> 
>> Thanks,
>> Tal
> 
> Yes, please forward to the vfs tree.
> 
> Acked-by: Nicolas Pitre <nico@fluxnic.net>
> 
Thanks!

Christian, could you please pick this up?

> 
>> > diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c
>> > index d4cd03f4f60d..b55eb3bd29c1 100644
>> > --- a/fs/cramfs/inode.c
>> > +++ b/fs/cramfs/inode.c
>> > @@ -194,7 +194,7 @@ static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset,
>> >  {
>> >  	struct address_space *mapping = sb->s_bdev->bd_mapping;
>> >  	struct file_ra_state ra = {};
>> > -	struct page *pages[BLKS_PER_BUF];
>> > +	struct folio *folios[BLKS_PER_BUF];
>> >  	unsigned i, blocknr, buffer;
>> >  	unsigned long devsize;
>> >  	char *data;
>> > @@ -227,15 +227,15 @@ static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset,
>> >  	page_cache_sync_readahead(mapping, &ra, NULL, blocknr, BLKS_PER_BUF);
>> >  
>> >  	for (i = 0; i < BLKS_PER_BUF; i++) {
>> > -		struct page *page = NULL;
>> > +		struct folio *folio = NULL;
>> >  
>> >  		if (blocknr + i < devsize) {
>> > -			page = read_mapping_page(mapping, blocknr + i, NULL);
>> > +			folio = read_mapping_folio(mapping, blocknr + i, NULL);
>> >  			/* synchronous error? */
>> > -			if (IS_ERR(page))
>> > -				page = NULL;
>> > +			if (IS_ERR(folio))
>> > +				folio = NULL;
>> >  		}
>> > -		pages[i] = page;
>> > +		folios[i] = folio;
>> >  	}
>> >  
>> >  	buffer = next_buffer;
>> > @@ -245,11 +245,14 @@ static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset,
>> >  
>> >  	data = read_buffers[buffer];
>> >  	for (i = 0; i < BLKS_PER_BUF; i++) {
>> > -		struct page *page = pages[i];
>> > +		struct folio *folio = folios[i];
>> >  
>> > -		if (page) {
>> > -			memcpy_from_page(data, page, 0, PAGE_SIZE);
>> > -			put_page(page);
>> > +		if (folio) {
>> > +			size_t offset = offset_in_folio(folio,
>> > +					(loff_t)(blocknr + i) << PAGE_SHIFT);
>> > +
>> > +			memcpy_from_folio(data, folio, offset, PAGE_SIZE);
>> > +			folio_put(folio);
>> >  		} else
>> >  			memset(data, 0, PAGE_SIZE);
>> >  		data += PAGE_SIZE;
>> > 
>> > ---
>> > base-commit: df2908090cda368b01ff43709f51890076c56157
>> > change-id: 20260906-cramfs-blkdev-read-folio-16fecf6908ac
>> > 
>> > Best regards,
>> > --  
>> > Tal Zussman <tz2294@columbia.edu>
>> 
>> 
> 

Re: [PATCH] cramfs: convert cramfs_blkdev_read() to use folios

[Christian Brauner]

On Sun, 06 Sep 2026 19:45:33 -0400, Tal Zussman wrote:
> Read the block device pages through read_mapping_folio() and copy with
> memcpy_from_folio() instead of going through a page.

Applied to the vfs-7.5.misc branch of the vfs/vfs.git tree.
Patches in the vfs-7.5.misc branch should appear in linux-next soon.

Please report any outstanding bugs that were missed during review in a
new review to the original patch series allowing us to drop it.

It's encouraged to provide Acked-bys and Reviewed-bys even though the
patch has now been applied. If possible patch trailers will be updated.

Note that commit hashes shown below are subject to change due to rebase,
trailer updates or similar. If in doubt, please check the listed branch.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
branch: vfs-7.5.misc

[1/1] cramfs: convert cramfs_blkdev_read() to use folios
      https://git.kernel.org/vfs/vfs/c/06e2e8febbcc