diff mbox series

[6/8] mm/swap: get the swap file offset directly

Message ID 20240417160842.76665-7-ryncsn@gmail.com (mailing list archive)
State New, archived
Headers show
Series mm/swap: optimize swap cache search space | expand

Commit Message

Kairui Song April 17, 2024, 4:08 p.m. UTC
From: Kairui Song <kasong@tencent.com>

folio_file_pos and page_file_offset are for mixed usage of swap cache
and page cache, it can't be page cache here, so introduce a new helper
to get the swap offset in swap file directly.

Signed-off-by: Kairui Song <kasong@tencent.com>
---
 mm/page_io.c | 6 +++---
 mm/swap.h    | 5 +++++
 2 files changed, 8 insertions(+), 3 deletions(-)

Comments

kernel test robot April 18, 2024, 6:43 p.m. UTC | #1
Hi Kairui,

kernel test robot noticed the following build errors:

[auto build test ERROR on ceph-client/testing]
[also build test ERROR on ceph-client/for-linus trondmy-nfs/linux-next konis-nilfs2/upstream jaegeuk-f2fs/dev-test jaegeuk-f2fs/dev cifs/for-next linus/master v6.9-rc4 next-20240418]
[cannot apply to akpm-mm/mm-everything]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Kairui-Song/NFS-remove-nfs_page_lengthg-and-usage-of-page_index/20240418-001343
base:   https://github.com/ceph/ceph-client.git testing
patch link:    https://lore.kernel.org/r/20240417160842.76665-7-ryncsn%40gmail.com
patch subject: [PATCH 6/8] mm/swap: get the swap file offset directly
config: alpha-defconfig (https://download.01.org/0day-ci/archive/20240419/202404190204.cy1pBxFg-lkp@intel.com/config)
compiler: alpha-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240419/202404190204.cy1pBxFg-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202404190204.cy1pBxFg-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from mm/shmem.c:43:
   mm/swap.h: In function 'swap_file_pos':
>> mm/swap.h:12:25: error: implicit declaration of function 'swp_offset'; did you mean 'pmd_offset'? [-Werror=implicit-function-declaration]
      12 |         return ((loff_t)swp_offset(entry)) << PAGE_SHIFT;
         |                         ^~~~~~~~~~
         |                         pmd_offset
   In file included from mm/shmem.c:68:
   include/linux/swapops.h: At top level:
>> include/linux/swapops.h:107:23: error: conflicting types for 'swp_offset'; have 'long unsigned int(swp_entry_t)'
     107 | static inline pgoff_t swp_offset(swp_entry_t entry)
         |                       ^~~~~~~~~~
   mm/swap.h:12:25: note: previous implicit declaration of 'swp_offset' with type 'int()'
      12 |         return ((loff_t)swp_offset(entry)) << PAGE_SHIFT;
         |                         ^~~~~~~~~~
   cc1: some warnings being treated as errors
--
   In file included from mm/show_mem.c:19:
   mm/swap.h: In function 'swap_file_pos':
>> mm/swap.h:12:25: error: implicit declaration of function 'swp_offset'; did you mean 'pmd_offset'? [-Werror=implicit-function-declaration]
      12 |         return ((loff_t)swp_offset(entry)) << PAGE_SHIFT;
         |                         ^~~~~~~~~~
         |                         pmd_offset
   cc1: some warnings being treated as errors


vim +12 mm/swap.h

     9	
    10	static inline loff_t swap_file_pos(swp_entry_t entry)
    11	{
  > 12		return ((loff_t)swp_offset(entry)) << PAGE_SHIFT;
    13	}
    14
Huang, Ying April 23, 2024, 1:41 a.m. UTC | #2
Kairui Song <ryncsn@gmail.com> writes:

> From: Kairui Song <kasong@tencent.com>
>
> folio_file_pos and page_file_offset are for mixed usage of swap cache
> and page cache, it can't be page cache here, so introduce a new helper
> to get the swap offset in swap file directly.
>
> Signed-off-by: Kairui Song <kasong@tencent.com>
> ---
>  mm/page_io.c | 6 +++---
>  mm/swap.h    | 5 +++++
>  2 files changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/mm/page_io.c b/mm/page_io.c
> index ae2b49055e43..93de5aadb438 100644
> --- a/mm/page_io.c
> +++ b/mm/page_io.c
> @@ -279,7 +279,7 @@ static void sio_write_complete(struct kiocb *iocb, long ret)
>  		 * be temporary.
>  		 */
>  		pr_err_ratelimited("Write error %ld on dio swapfile (%llu)\n",
> -				   ret, page_file_offset(page));
> +				   ret, swap_file_pos(page_swap_entry(page)));
>  		for (p = 0; p < sio->pages; p++) {
>  			page = sio->bvec[p].bv_page;
>  			set_page_dirty(page);
> @@ -298,7 +298,7 @@ static void swap_writepage_fs(struct folio *folio, struct writeback_control *wbc
>  	struct swap_iocb *sio = NULL;
>  	struct swap_info_struct *sis = swp_swap_info(folio->swap);
>  	struct file *swap_file = sis->swap_file;
> -	loff_t pos = folio_file_pos(folio);
> +	loff_t pos = swap_file_pos(folio->swap);
>  
>  	count_swpout_vm_event(folio);
>  	folio_start_writeback(folio);
> @@ -429,7 +429,7 @@ static void swap_read_folio_fs(struct folio *folio, struct swap_iocb **plug)
>  {
>  	struct swap_info_struct *sis = swp_swap_info(folio->swap);
>  	struct swap_iocb *sio = NULL;
> -	loff_t pos = folio_file_pos(folio);
> +	loff_t pos = swap_file_pos(folio->swap);
>  
>  	if (plug)
>  		sio = *plug;
> diff --git a/mm/swap.h b/mm/swap.h
> index fc2f6ade7f80..2de83729aaa8 100644
> --- a/mm/swap.h
> +++ b/mm/swap.h
> @@ -7,6 +7,11 @@ struct mempolicy;
>  #ifdef CONFIG_SWAP
>  #include <linux/blk_types.h> /* for bio_end_io_t */
>  
> +static inline loff_t swap_file_pos(swp_entry_t entry)
> +{
> +	return ((loff_t)swp_offset(entry)) << PAGE_SHIFT;
> +}
> +
>  /* linux/mm/page_io.c */
>  int sio_pool_init(void);
>  struct swap_iocb;

I feel that the file concept for swap is kind of confusing.  From the
file cache point of view, one "struct address space" conresponds to one
file.  If so, we have a simple file system on a swap device (block
device backed or file backed), where the size of each file is 64M.  The
swap entry encode the file system (swap_type), the file name
(swap_offset >> SWAP_ADDRESS_SPACE_SHIFT), and the offset in file (lower
bits of swap_offset).

If the above definition is good, it's better to rename swap_file_pos()
to swap_dev_pos(), because it returns the swap device position of the
swap entry.

And, when we reaches consensus on the swap file related concept, we may
document it somewhere and review all naming in swap code to cleanup.

--
Best Regards,
Huang, Ying
Kairui Song April 23, 2024, 1:33 p.m. UTC | #3
On Tue, Apr 23, 2024 at 9:43 AM Huang, Ying <ying.huang@intel.com> wrote:
>
> Kairui Song <ryncsn@gmail.com> writes:
>
> > From: Kairui Song <kasong@tencent.com>
> >
> > folio_file_pos and page_file_offset are for mixed usage of swap cache
> > and page cache, it can't be page cache here, so introduce a new helper
> > to get the swap offset in swap file directly.
> >
> > Signed-off-by: Kairui Song <kasong@tencent.com>
> > ---
> >  mm/page_io.c | 6 +++---
> >  mm/swap.h    | 5 +++++
> >  2 files changed, 8 insertions(+), 3 deletions(-)
> >
> > diff --git a/mm/page_io.c b/mm/page_io.c
> > index ae2b49055e43..93de5aadb438 100644
> > --- a/mm/page_io.c
> > +++ b/mm/page_io.c
> > @@ -279,7 +279,7 @@ static void sio_write_complete(struct kiocb *iocb, long ret)
> >                * be temporary.
> >                */
> >               pr_err_ratelimited("Write error %ld on dio swapfile (%llu)\n",
> > -                                ret, page_file_offset(page));
> > +                                ret, swap_file_pos(page_swap_entry(page)));
> >               for (p = 0; p < sio->pages; p++) {
> >                       page = sio->bvec[p].bv_page;
> >                       set_page_dirty(page);
> > @@ -298,7 +298,7 @@ static void swap_writepage_fs(struct folio *folio, struct writeback_control *wbc
> >       struct swap_iocb *sio = NULL;
> >       struct swap_info_struct *sis = swp_swap_info(folio->swap);
> >       struct file *swap_file = sis->swap_file;
> > -     loff_t pos = folio_file_pos(folio);
> > +     loff_t pos = swap_file_pos(folio->swap);
> >
> >       count_swpout_vm_event(folio);
> >       folio_start_writeback(folio);
> > @@ -429,7 +429,7 @@ static void swap_read_folio_fs(struct folio *folio, struct swap_iocb **plug)
> >  {
> >       struct swap_info_struct *sis = swp_swap_info(folio->swap);
> >       struct swap_iocb *sio = NULL;
> > -     loff_t pos = folio_file_pos(folio);
> > +     loff_t pos = swap_file_pos(folio->swap);
> >
> >       if (plug)
> >               sio = *plug;
> > diff --git a/mm/swap.h b/mm/swap.h
> > index fc2f6ade7f80..2de83729aaa8 100644
> > --- a/mm/swap.h
> > +++ b/mm/swap.h
> > @@ -7,6 +7,11 @@ struct mempolicy;
> >  #ifdef CONFIG_SWAP
> >  #include <linux/blk_types.h> /* for bio_end_io_t */
> >
> > +static inline loff_t swap_file_pos(swp_entry_t entry)
> > +{
> > +     return ((loff_t)swp_offset(entry)) << PAGE_SHIFT;
> > +}
> > +
> >  /* linux/mm/page_io.c */
> >  int sio_pool_init(void);
> >  struct swap_iocb;
>
> I feel that the file concept for swap is kind of confusing.  From the
> file cache point of view, one "struct address space" conresponds to one
> file.  If so, we have a simple file system on a swap device (block
> device backed or file backed), where the size of each file is 64M.  The
> swap entry encode the file system (swap_type), the file name
> (swap_offset >> SWAP_ADDRESS_SPACE_SHIFT), and the offset in file (lower
> bits of swap_offset).
>
> If the above definition is good, it's better to rename swap_file_pos()
> to swap_dev_pos(), because it returns the swap device position of the
> swap entry.

Good suggestion! The definition looks good to me, swap_dev_pos also
looks better, "swap_file" looks confusing indeed.

>
> And, when we reaches consensus on the swap file related concept, we may
> document it somewhere and review all naming in swap code to cleanup.
>
> --
> Best Regards,
> Huang, Ying
diff mbox series

Patch

diff --git a/mm/page_io.c b/mm/page_io.c
index ae2b49055e43..93de5aadb438 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -279,7 +279,7 @@  static void sio_write_complete(struct kiocb *iocb, long ret)
 		 * be temporary.
 		 */
 		pr_err_ratelimited("Write error %ld on dio swapfile (%llu)\n",
-				   ret, page_file_offset(page));
+				   ret, swap_file_pos(page_swap_entry(page)));
 		for (p = 0; p < sio->pages; p++) {
 			page = sio->bvec[p].bv_page;
 			set_page_dirty(page);
@@ -298,7 +298,7 @@  static void swap_writepage_fs(struct folio *folio, struct writeback_control *wbc
 	struct swap_iocb *sio = NULL;
 	struct swap_info_struct *sis = swp_swap_info(folio->swap);
 	struct file *swap_file = sis->swap_file;
-	loff_t pos = folio_file_pos(folio);
+	loff_t pos = swap_file_pos(folio->swap);
 
 	count_swpout_vm_event(folio);
 	folio_start_writeback(folio);
@@ -429,7 +429,7 @@  static void swap_read_folio_fs(struct folio *folio, struct swap_iocb **plug)
 {
 	struct swap_info_struct *sis = swp_swap_info(folio->swap);
 	struct swap_iocb *sio = NULL;
-	loff_t pos = folio_file_pos(folio);
+	loff_t pos = swap_file_pos(folio->swap);
 
 	if (plug)
 		sio = *plug;
diff --git a/mm/swap.h b/mm/swap.h
index fc2f6ade7f80..2de83729aaa8 100644
--- a/mm/swap.h
+++ b/mm/swap.h
@@ -7,6 +7,11 @@  struct mempolicy;
 #ifdef CONFIG_SWAP
 #include <linux/blk_types.h> /* for bio_end_io_t */
 
+static inline loff_t swap_file_pos(swp_entry_t entry)
+{
+	return ((loff_t)swp_offset(entry)) << PAGE_SHIFT;
+}
+
 /* linux/mm/page_io.c */
 int sio_pool_init(void);
 struct swap_iocb;