From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx> Some filesystems want to be able to limit the maximum size of folios, and some want to be able to ensure that folios are at least a certain size. Add mapping_set_folio_orders() to allow this level of control. The max folio order parameter is ignored and it is always set to MAX_PAGECACHE_ORDER. Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Signed-off-by: Pankaj Raghav <p.raghav@xxxxxxxxxxx> Signed-off-by: Luis Chamberlain <mcgrof@xxxxxxxxxx> --- include/linux/pagemap.h | 92 ++++++++++++++++++++++++++++++++--------- 1 file changed, 73 insertions(+), 19 deletions(-) diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 2df35e65557d..5618f762187b 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -202,13 +202,18 @@ enum mapping_flags { AS_EXITING = 4, /* final truncate in progress */ /* writeback related tags are not used */ AS_NO_WRITEBACK_TAGS = 5, - AS_LARGE_FOLIO_SUPPORT = 6, - AS_RELEASE_ALWAYS, /* Call ->release_folio(), even if no private data */ - AS_STABLE_WRITES, /* must wait for writeback before modifying + AS_RELEASE_ALWAYS = 6, /* Call ->release_folio(), even if no private data */ + AS_STABLE_WRITES = 7, /* must wait for writeback before modifying folio contents */ - AS_UNMOVABLE, /* The mapping cannot be moved, ever */ + AS_FOLIO_ORDER_MIN = 8, + AS_FOLIO_ORDER_MAX = 13, /* Bit 8-17 are used for FOLIO_ORDER */ + AS_UNMOVABLE = 18, /* The mapping cannot be moved, ever */ }; +#define AS_FOLIO_ORDER_MIN_MASK 0x00001f00 +#define AS_FOLIO_ORDER_MAX_MASK 0x0003e000 +#define AS_FOLIO_ORDER_MASK (AS_FOLIO_ORDER_MIN_MASK | AS_FOLIO_ORDER_MAX_MASK) + /** * mapping_set_error - record a writeback error in the address_space * @mapping: the mapping in which an error should be set @@ -344,6 +349,53 @@ static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask) m->gfp_mask = mask; } +/* + * There are some parts of the kernel which assume that PMD entries + * are exactly HPAGE_PMD_ORDER. Those should be fixed, but until then, + * limit the maximum allocation order to PMD size. I'm not aware of any + * assumptions about maximum order if THP are disabled, but 8 seems like + * a good order (that's 1MB if you're using 4kB pages) + */ +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +#define MAX_PAGECACHE_ORDER HPAGE_PMD_ORDER +#else +#define MAX_PAGECACHE_ORDER 8 +#endif + +/* + * mapping_set_folio_orders() - Set the range of folio sizes supported. + * @mapping: The file. + * @min: Minimum folio order (between 0-MAX_PAGECACHE_ORDER inclusive). + * @max: Maximum folio order (between 0-MAX_PAGECACHE_ORDER inclusive). + * + * The filesystem should call this function in its inode constructor to + * indicate which sizes of folio the VFS can use to cache the contents + * of the file. This should only be used if the filesystem needs special + * handling of folio sizes (ie there is something the core cannot know). + * Do not tune it based on, eg, i_size. + * + * Context: This should not be called while the inode is active as it + * is non-atomic. + */ +static inline void mapping_set_folio_orders(struct address_space *mapping, + unsigned int min, unsigned int max) +{ + if (min == 1) + min = 2; + if (max < min) + max = min; + if (max > MAX_PAGECACHE_ORDER) + max = MAX_PAGECACHE_ORDER; + + /* + * XXX: max is ignored as only minimum folio order is supported + * currently. + */ + mapping->flags = (mapping->flags & ~AS_FOLIO_ORDER_MASK) | + (min << AS_FOLIO_ORDER_MIN) | + (MAX_PAGECACHE_ORDER << AS_FOLIO_ORDER_MAX); +} + /** * mapping_set_large_folios() - Indicate the file supports large folios. * @mapping: The file. @@ -357,7 +409,22 @@ static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask) */ static inline void mapping_set_large_folios(struct address_space *mapping) { - __set_bit(AS_LARGE_FOLIO_SUPPORT, &mapping->flags); + mapping_set_folio_orders(mapping, 0, MAX_PAGECACHE_ORDER); +} + +static inline unsigned int mapping_max_folio_order(struct address_space *mapping) +{ + return (mapping->flags & AS_FOLIO_ORDER_MAX_MASK) >> AS_FOLIO_ORDER_MAX; +} + +static inline unsigned int mapping_min_folio_order(struct address_space *mapping) +{ + return (mapping->flags & AS_FOLIO_ORDER_MIN_MASK) >> AS_FOLIO_ORDER_MIN; +} + +static inline unsigned int mapping_min_folio_nrpages(struct address_space *mapping) +{ + return 1U << mapping_min_folio_order(mapping); } /* @@ -367,7 +434,7 @@ static inline void mapping_set_large_folios(struct address_space *mapping) static inline bool mapping_large_folio_support(struct address_space *mapping) { return IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && - test_bit(AS_LARGE_FOLIO_SUPPORT, &mapping->flags); + (mapping_max_folio_order(mapping) > 0); } static inline int filemap_nr_thps(struct address_space *mapping) @@ -528,19 +595,6 @@ static inline void *detach_page_private(struct page *page) return folio_detach_private(page_folio(page)); } -/* - * There are some parts of the kernel which assume that PMD entries - * are exactly HPAGE_PMD_ORDER. Those should be fixed, but until then, - * limit the maximum allocation order to PMD size. I'm not aware of any - * assumptions about maximum order if THP are disabled, but 8 seems like - * a good order (that's 1MB if you're using 4kB pages) - */ -#ifdef CONFIG_TRANSPARENT_HUGEPAGE -#define MAX_PAGECACHE_ORDER HPAGE_PMD_ORDER -#else -#define MAX_PAGECACHE_ORDER 8 -#endif - #ifdef CONFIG_NUMA struct folio *filemap_alloc_folio(gfp_t gfp, unsigned int order); #else -- 2.43.0