diff mbox series

[v3,03/11] filemap: allocate mapping_min_order folios in the page cache

Message ID 20240313170253.2324812-4-kernel@pankajraghav.com (mailing list archive)
State New
Headers show
Series enable bs > ps in XFS | expand

Commit Message

Pankaj Raghav (Samsung) March 13, 2024, 5:02 p.m. UTC 
From: Luis Chamberlain <mcgrof@kernel.org>

filemap_create_folio() and do_read_cache_folio() were always allocating
folio of order 0. __filemap_get_folio was trying to allocate higher
order folios when fgp_flags had higher order hint set but it will default
to order 0 folio if higher order memory allocation fails.

Supporting mapping_min_order implies that we guarantee each folio in the
page cache has at least an order of mapping_min_order. When adding new
folios to the page cache we must also ensure the index used is aligned to
the mapping_min_order as the page cache requires the index to be aligned
to the order of the folio.

Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Co-developed-by: Pankaj Raghav <p.raghav@samsung.com>
Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
---
 mm/filemap.c | 24 +++++++++++++++++-------
 1 file changed, 17 insertions(+), 7 deletions(-)

Comments

Pankaj Raghav (Samsung) March 15, 2024, 1:21 p.m. UTC | #1 
Hi willy,

> filemap_create_folio() and do_read_cache_folio() were always allocating
> folio of order 0. __filemap_get_folio was trying to allocate higher
> order folios when fgp_flags had higher order hint set but it will default
> to order 0 folio if higher order memory allocation fails.
> 
> Supporting mapping_min_order implies that we guarantee each folio in the
> page cache has at least an order of mapping_min_order. When adding new
> folios to the page cache we must also ensure the index used is aligned to
> the mapping_min_order as the page cache requires the index to be aligned
> to the order of the folio.
> 
> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
> Co-developed-by: Pankaj Raghav <p.raghav@samsung.com>
> Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
> ---
>  mm/filemap.c | 24 +++++++++++++++++-------
>  1 file changed, 17 insertions(+), 7 deletions(-)

Are the changes more inline with what you had in mind?

> 
> diff --git a/mm/filemap.c b/mm/filemap.c
> index a1cb3ea55fb6..57889f206829 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -849,6 +849,8 @@ noinline int __filemap_add_folio(struct address_space *mapping,
>  
>  	VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
>  	VM_BUG_ON_FOLIO(folio_test_swapbacked(folio), folio);
> +	VM_BUG_ON_FOLIO(folio_order(folio) < mapping_min_folio_order(mapping),
> +			folio);
>  	mapping_set_update(&xas, mapping);
>  
>  	if (!huge) {
> @@ -1886,8 +1888,10 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
>  		folio_wait_stable(folio);
>  no_page:
>  	if (!folio && (fgp_flags & FGP_CREAT)) {
> -		unsigned order = FGF_GET_ORDER(fgp_flags);
> +		unsigned int min_order = mapping_min_folio_order(mapping);
> +		unsigned int order = max(min_order, FGF_GET_ORDER(fgp_flags));
>  		int err;
> +		index = mapping_align_start_index(mapping, index);
>  
>  		if ((fgp_flags & FGP_WRITE) && mapping_can_writeback(mapping))
>  			gfp |= __GFP_WRITE;
> @@ -1927,7 +1931,7 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
>  				break;
>  			folio_put(folio);
>  			folio = NULL;
> -		} while (order-- > 0);
> +		} while (order-- > min_order);
>  
>  		if (err == -EEXIST)
>  			goto repeat;
> @@ -2416,13 +2420,16 @@ static int filemap_update_page(struct kiocb *iocb,
>  }
>  
>  static int filemap_create_folio(struct file *file,
> -		struct address_space *mapping, pgoff_t index,
> +		struct address_space *mapping, loff_t pos,
>  		struct folio_batch *fbatch)
>  {
>  	struct folio *folio;
>  	int error;
> +	unsigned int min_order = mapping_min_folio_order(mapping);
> +	pgoff_t index;
>  
> -	folio = filemap_alloc_folio(mapping_gfp_mask(mapping), 0);
> +	folio = filemap_alloc_folio(mapping_gfp_mask(mapping),
> +				    min_order);
>  	if (!folio)
>  		return -ENOMEM;
>  
> @@ -2440,6 +2447,8 @@ static int filemap_create_folio(struct file *file,
>  	 * well to keep locking rules simple.
>  	 */
>  	filemap_invalidate_lock_shared(mapping);
> +	/* index in PAGE units but aligned to min_order number of pages. */
> +	index = (pos >> (PAGE_SHIFT + min_order)) << min_order;
>  	error = filemap_add_folio(mapping, folio, index,
>  			mapping_gfp_constraint(mapping, GFP_KERNEL));
>  	if (error == -EEXIST)
> @@ -2500,8 +2509,7 @@ static int filemap_get_pages(struct kiocb *iocb, size_t count,
>  	if (!folio_batch_count(fbatch)) {
>  		if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_WAITQ))
>  			return -EAGAIN;
> -		err = filemap_create_folio(filp, mapping,
> -				iocb->ki_pos >> PAGE_SHIFT, fbatch);
> +		err = filemap_create_folio(filp, mapping, iocb->ki_pos, fbatch);
>  		if (err == AOP_TRUNCATED_PAGE)
>  			goto retry;
>  		return err;
> @@ -3662,9 +3670,11 @@ static struct folio *do_read_cache_folio(struct address_space *mapping,
>  repeat:
>  	folio = filemap_get_folio(mapping, index);
>  	if (IS_ERR(folio)) {
> -		folio = filemap_alloc_folio(gfp, 0);
> +		folio = filemap_alloc_folio(gfp,
> +					    mapping_min_folio_order(mapping));
>  		if (!folio)
>  			return ERR_PTR(-ENOMEM);
> +		index = mapping_align_start_index(mapping, index);
>  		err = filemap_add_folio(mapping, folio, index, gfp);
>  		if (unlikely(err)) {
>  			folio_put(folio);
> -- 
> 2.43.0
>
diff mbox series

Patch

diff --git a/mm/filemap.c b/mm/filemap.c
index a1cb3ea55fb6..57889f206829 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -849,6 +849,8 @@  noinline int __filemap_add_folio(struct address_space *mapping,
 
 	VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
 	VM_BUG_ON_FOLIO(folio_test_swapbacked(folio), folio);
+	VM_BUG_ON_FOLIO(folio_order(folio) < mapping_min_folio_order(mapping),
+			folio);
 	mapping_set_update(&xas, mapping);
 
 	if (!huge) {
@@ -1886,8 +1888,10 @@  struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
 		folio_wait_stable(folio);
 no_page:
 	if (!folio && (fgp_flags & FGP_CREAT)) {
-		unsigned order = FGF_GET_ORDER(fgp_flags);
+		unsigned int min_order = mapping_min_folio_order(mapping);
+		unsigned int order = max(min_order, FGF_GET_ORDER(fgp_flags));
 		int err;
+		index = mapping_align_start_index(mapping, index);
 
 		if ((fgp_flags & FGP_WRITE) && mapping_can_writeback(mapping))
 			gfp |= __GFP_WRITE;
@@ -1927,7 +1931,7 @@  struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
 				break;
 			folio_put(folio);
 			folio = NULL;
-		} while (order-- > 0);
+		} while (order-- > min_order);
 
 		if (err == -EEXIST)
 			goto repeat;
@@ -2416,13 +2420,16 @@  static int filemap_update_page(struct kiocb *iocb,
 }
 
 static int filemap_create_folio(struct file *file,
-		struct address_space *mapping, pgoff_t index,
+		struct address_space *mapping, loff_t pos,
 		struct folio_batch *fbatch)
 {
 	struct folio *folio;
 	int error;
+	unsigned int min_order = mapping_min_folio_order(mapping);
+	pgoff_t index;
 
-	folio = filemap_alloc_folio(mapping_gfp_mask(mapping), 0);
+	folio = filemap_alloc_folio(mapping_gfp_mask(mapping),
+				    min_order);
 	if (!folio)
 		return -ENOMEM;
 
@@ -2440,6 +2447,8 @@  static int filemap_create_folio(struct file *file,
 	 * well to keep locking rules simple.
 	 */
 	filemap_invalidate_lock_shared(mapping);
+	/* index in PAGE units but aligned to min_order number of pages. */
+	index = (pos >> (PAGE_SHIFT + min_order)) << min_order;
 	error = filemap_add_folio(mapping, folio, index,
 			mapping_gfp_constraint(mapping, GFP_KERNEL));
 	if (error == -EEXIST)
@@ -2500,8 +2509,7 @@  static int filemap_get_pages(struct kiocb *iocb, size_t count,
 	if (!folio_batch_count(fbatch)) {
 		if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_WAITQ))
 			return -EAGAIN;
-		err = filemap_create_folio(filp, mapping,
-				iocb->ki_pos >> PAGE_SHIFT, fbatch);
+		err = filemap_create_folio(filp, mapping, iocb->ki_pos, fbatch);
 		if (err == AOP_TRUNCATED_PAGE)
 			goto retry;
 		return err;
@@ -3662,9 +3670,11 @@  static struct folio *do_read_cache_folio(struct address_space *mapping,
 repeat:
 	folio = filemap_get_folio(mapping, index);
 	if (IS_ERR(folio)) {
-		folio = filemap_alloc_folio(gfp, 0);
+		folio = filemap_alloc_folio(gfp,
+					    mapping_min_folio_order(mapping));
 		if (!folio)
 			return ERR_PTR(-ENOMEM);
+		index = mapping_align_start_index(mapping, index);
 		err = filemap_add_folio(mapping, folio, index, gfp);
 		if (unlikely(err)) {
 			folio_put(folio);