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Wong" To: "Pankaj Raghav (Samsung)" Cc: david@fromorbit.com, chandan.babu@oracle.com, brauner@kernel.org, akpm@linux-foundation.org, willy@infradead.org, mcgrof@kernel.org, linux-mm@kvack.org, hare@suse.de, linux-kernel@vger.kernel.org, yang@os.amperecomputing.com, Zi Yan , linux-xfs@vger.kernel.org, p.raghav@samsung.com, linux-fsdevel@vger.kernel.org, hch@lst.de, gost.dev@samsung.com, cl@os.amperecomputing.com, john.g.garry@oracle.com Subject: Re: [PATCH v7 02/11] fs: Allow fine-grained control of folio sizes Message-ID: <20240612153818.GA2764752@frogsfrogsfrogs> References: <20240607145902.1137853-1-kernel@pankajraghav.com> <20240607145902.1137853-3-kernel@pankajraghav.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240607145902.1137853-3-kernel@pankajraghav.com> X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: E070940017 X-Stat-Signature: cf5tdntbckji4d18zi7usdtbmu3d644n X-HE-Tag: 1718206702-704894 X-HE-Meta: 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 KALrZFQw 0zcSDxvVPWTcJzd2bIP9uK0naTJRav5rxFdkU9BHFJs6o74uUzZ7cnzijQEhjPhGTl5MgeXZ+M0BlgRjw7+tdQSK0r4aDc2pSHHfkkY1syeKtY7RtxF++1aajt0KZtLYZzNk6mg2Ok/bDmUIu36BdhMzYVFXGkYCj7W5FaDaAWW5jk78VHLr/guNdErd3qnuHFUQW6uMKyT1VnIQ9+R8DxfYrdQhNazH0sRvzD5wvUjCXme9zohzov7UlUgcPDqf90uKxTzv7/aXyyqLFiOZS0qyT3vlGqY1lAvMpOdeGO9MXjMXKNN/MIqgJIpHYGPaxXrVQmz+iY/7OH3w= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Jun 07, 2024 at 02:58:53PM +0000, Pankaj Raghav (Samsung) wrote: > From: "Matthew Wilcox (Oracle)" > > We need filesystems to be able to communicate acceptable folio sizes > to the pagecache for a variety of uses (e.g. large block sizes). > Support a range of folio sizes between order-0 and order-31. > > Signed-off-by: Matthew Wilcox (Oracle) > Co-developed-by: Pankaj Raghav > Signed-off-by: Pankaj Raghav > Reviewed-by: Hannes Reinecke Looks good to me, Reviewed-by: Darrick J. Wong --D > --- > include/linux/pagemap.h | 86 ++++++++++++++++++++++++++++++++++------- > mm/filemap.c | 6 +-- > mm/readahead.c | 4 +- > 3 files changed, 77 insertions(+), 19 deletions(-) > > diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h > index 8f09ed4a4451..228275e7049f 100644 > --- a/include/linux/pagemap.h > +++ b/include/linux/pagemap.h > @@ -204,14 +204,21 @@ 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_INACCESSIBLE, /* Do not attempt direct R/W access to the mapping */ > + AS_UNMOVABLE = 8, /* The mapping cannot be moved, ever */ > + AS_INACCESSIBLE = 9, /* Do not attempt direct R/W access to the mapping */ > + /* Bits 16-25 are used for FOLIO_ORDER */ > + AS_FOLIO_ORDER_BITS = 5, > + AS_FOLIO_ORDER_MIN = 16, > + AS_FOLIO_ORDER_MAX = AS_FOLIO_ORDER_MIN + AS_FOLIO_ORDER_BITS, > }; > > +#define AS_FOLIO_ORDER_MASK ((1u << AS_FOLIO_ORDER_BITS) - 1) > +#define AS_FOLIO_ORDER_MIN_MASK (AS_FOLIO_ORDER_MASK << AS_FOLIO_ORDER_MIN) > +#define AS_FOLIO_ORDER_MAX_MASK (AS_FOLIO_ORDER_MASK << AS_FOLIO_ORDER_MAX) > + > /** > * mapping_set_error - record a writeback error in the address_space > * @mapping: the mapping in which an error should be set > @@ -360,9 +367,49 @@ static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask) > #define MAX_PAGECACHE_ORDER 8 > #endif > > +/* > + * mapping_set_folio_order_range() - Set the orders supported by a file. > + * @mapping: The address space of the file. > + * @min: Minimum folio order (between 0-MAX_PAGECACHE_ORDER inclusive). > + * @max: Maximum folio order (between @min-MAX_PAGECACHE_ORDER inclusive). > + * > + * The filesystem should call this function in its inode constructor to > + * indicate which base size (min) and maximum size (max) 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_order_range(struct address_space *mapping, > + unsigned int min, > + unsigned int max) > +{ > + if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) > + return; > + > + if (min > MAX_PAGECACHE_ORDER) > + min = MAX_PAGECACHE_ORDER; > + if (max > MAX_PAGECACHE_ORDER) > + max = MAX_PAGECACHE_ORDER; > + if (max < min) > + max = min; > + > + mapping->flags = (mapping->flags & ~AS_FOLIO_ORDER_MASK) | > + (min << AS_FOLIO_ORDER_MIN) | (max << AS_FOLIO_ORDER_MAX); > +} > + > +static inline void mapping_set_folio_min_order(struct address_space *mapping, > + unsigned int min) > +{ > + mapping_set_folio_order_range(mapping, min, MAX_PAGECACHE_ORDER); > +} > + > /** > * mapping_set_large_folios() - Indicate the file supports large folios. > - * @mapping: The file. > + * @mapping: The address space of the file. > * > * The filesystem should call this function in its inode constructor to > * indicate that the VFS can use large folios to cache the contents of > @@ -373,7 +420,23 @@ 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_order_range(mapping, 0, MAX_PAGECACHE_ORDER); > +} > + > +static inline > +unsigned int mapping_max_folio_order(const struct address_space *mapping) > +{ > + if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) > + return 0; > + return (mapping->flags & AS_FOLIO_ORDER_MAX_MASK) >> AS_FOLIO_ORDER_MAX; > +} > + > +static inline > +unsigned int mapping_min_folio_order(const struct address_space *mapping) > +{ > + if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) > + return 0; > + return (mapping->flags & AS_FOLIO_ORDER_MIN_MASK) >> AS_FOLIO_ORDER_MIN; > } > > /* > @@ -382,16 +445,13 @@ 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); > + return mapping_max_folio_order(mapping) > 0; > } > > /* Return the maximum folio size for this pagecache mapping, in bytes. */ > -static inline size_t mapping_max_folio_size(struct address_space *mapping) > +static inline size_t mapping_max_folio_size(const struct address_space *mapping) > { > - if (mapping_large_folio_support(mapping)) > - return PAGE_SIZE << MAX_PAGECACHE_ORDER; > - return PAGE_SIZE; > + return PAGE_SIZE << mapping_max_folio_order(mapping); > } > > static inline int filemap_nr_thps(struct address_space *mapping) > diff --git a/mm/filemap.c b/mm/filemap.c > index 37061aafd191..46c7a6f59788 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -1933,10 +1933,8 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index, > if (WARN_ON_ONCE(!(fgp_flags & (FGP_LOCK | FGP_FOR_MMAP)))) > fgp_flags |= FGP_LOCK; > > - if (!mapping_large_folio_support(mapping)) > - order = 0; > - if (order > MAX_PAGECACHE_ORDER) > - order = MAX_PAGECACHE_ORDER; > + if (order > mapping_max_folio_order(mapping)) > + order = mapping_max_folio_order(mapping); > /* If we're not aligned, allocate a smaller folio */ > if (index & ((1UL << order) - 1)) > order = __ffs(index); > diff --git a/mm/readahead.c b/mm/readahead.c > index 75e934a1fd78..da34b28da02c 100644 > --- a/mm/readahead.c > +++ b/mm/readahead.c > @@ -504,9 +504,9 @@ void page_cache_ra_order(struct readahead_control *ractl, > > limit = min(limit, index + ra->size - 1); > > - if (new_order < MAX_PAGECACHE_ORDER) { > + if (new_order < mapping_max_folio_order(mapping)) { > new_order += 2; > - new_order = min_t(unsigned int, MAX_PAGECACHE_ORDER, new_order); > + new_order = min(mapping_max_folio_order(mapping), new_order); > new_order = min_t(unsigned int, new_order, ilog2(ra->size)); > } > > -- > 2.44.1 > >