From nobody Sun Feb 8 11:17:08 2026 Received: from mout-p-202.mailbox.org (mout-p-202.mailbox.org [80.241.56.172]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E60884417; Fri, 1 Mar 2024 16:45:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=80.241.56.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709311506; cv=none; b=C4EzVsTNWKU8W7QvHDp6QAWvwICcHQlrrmnqk3LTkzZINnOG0TEba9UxrftdlPO8Fpnd2vjMCAkQzfykviBstFGBcjCxISOGRp/kUKcSQQR9TZ6pTdKTbc34R/UhHvDAlEnvxghi+jEyXuxsEa3B8LBzhsYeMYku8PaCBMnmzXw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709311506; c=relaxed/simple; bh=FOON1o0mymLuX2IKmggEuVP3QW7GlR7Lcz6UZhHnvAM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=HiH6kncvim5OTZS67pd7kkp6SOW9MmWg9GnEbEvcS9NnhwqvUatbNRUcx3Bs9R7w3K67OBgEMQQq+MpLhnqzEg/iNu2deWqZto0qP4hCr3po7Oa0wDJexgaTTTArh6h/HSn6inwNmFzGtBtGPZBxuummtz5xnElczYjgFLgg4Wk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=pankajraghav.com; spf=pass smtp.mailfrom=pankajraghav.com; dkim=pass (2048-bit key) header.d=pankajraghav.com header.i=@pankajraghav.com header.b=bL8wu3wN; arc=none smtp.client-ip=80.241.56.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=pankajraghav.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=pankajraghav.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=pankajraghav.com header.i=@pankajraghav.com header.b="bL8wu3wN" Received: from smtp102.mailbox.org (smtp102.mailbox.org [IPv6:2001:67c:2050:b231:465::102]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mout-p-202.mailbox.org (Postfix) with ESMTPS id 4TmYpv5Blmz9tW4; Fri, 1 Mar 2024 17:44:55 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=pankajraghav.com; s=MBO0001; t=1709311495; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=1cELEozXOYCd1Af2ZXfddDuv3Odm1CWuSBqyYDa15DQ=; b=bL8wu3wNKf1pmc8SzUQPy23UfUZ0BwEQ8+fDKjHUH8N+j2+VBUy1OSkewMRkC5mKZ/EWvp rQuqv1J8e6Vp3ePcwqreNd8Np8dNup0i92iIQy96VkqcjsyAawLjiJLYav4gsGGdCUNmcA 2lGI++nSQTqWERFoQA7n7WWLsY9t5UfQJiaX3aM0PHMZ1pJ+ckJtG93Tf9a5Cm/n06wnT9 r0yuN/PlrhcScbNCXn5iUOCg5Nt2ipmOpo8lK8BVQhqzgMJWClHr3TjBA7+wIS08h+1l3a s22J69b1C9/Y8dEvw0GLItEqLOMZw1U5cE+ygJdpzWGZ+pPT5Kpw6pzwE1ZHZA== From: "Pankaj Raghav (Samsung)" To: linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org Cc: djwong@kernel.org, mcgrof@kernel.org, linux-mm@kvack.org, hare@suse.de, david@fromorbit.com, akpm@linux-foundation.org, gost.dev@samsung.com, linux-kernel@vger.kernel.org, chandan.babu@oracle.com, willy@infradead.org, Pankaj Raghav Subject: [PATCH v2 02/13] fs: Allow fine-grained control of folio sizes Date: Fri, 1 Mar 2024 17:44:33 +0100 Message-ID: <20240301164444.3799288-3-kernel@pankajraghav.com> In-Reply-To: <20240301164444.3799288-1-kernel@pankajraghav.com> References: <20240301164444.3799288-1-kernel@pankajraghav.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 4TmYpv5Blmz9tW4 Content-Type: text/plain; charset="utf-8" From: "Matthew Wilcox (Oracle)" Some filesystems want to be able to ensure that folios that are added to the page cache are at least a certain size. Add mapping_set_folio_min_order() to allow this level of control. Signed-off-by: Matthew Wilcox (Oracle) Co-developed-by: Pankaj Raghav Signed-off-by: Pankaj Raghav Signed-off-by: Luis Chamberlain Reviewed-by: Hannes Reinecke --- include/linux/pagemap.h | 100 ++++++++++++++++++++++++++++++++-------- 1 file changed, 80 insertions(+), 20 deletions(-) diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 2df35e65557d..fc8eb9c94e9c 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -202,13 +202,18 @@ enum mapping_flags { AS_EXITING =3D 4, /* final truncate in progress */ /* writeback related tags are not used */ AS_NO_WRITEBACK_TAGS =3D 5, - AS_LARGE_FOLIO_SUPPORT =3D 6, - AS_RELEASE_ALWAYS, /* Call ->release_folio(), even if no private data */ - AS_STABLE_WRITES, /* must wait for writeback before modifying + AS_RELEASE_ALWAYS =3D 6, /* Call ->release_folio(), even if no private da= ta */ + AS_STABLE_WRITES =3D 7, /* must wait for writeback before modifying folio contents */ - AS_UNMOVABLE, /* The mapping cannot be moved, ever */ + AS_FOLIO_ORDER_MIN =3D 8, + AS_FOLIO_ORDER_MAX =3D 13, /* Bit 8-17 are used for FOLIO_ORDER */ + AS_UNMOVABLE =3D 18, /* The mapping cannot be moved, ever */ }; =20 +#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 @@ -344,9 +349,47 @@ static inline void mapping_set_gfp_mask(struct address= _space *m, gfp_t mask) m->gfp_mask =3D mask; } =20 +/* + * 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_min_order() - Set the minimum folio order + * @mapping: The address_space. + * @min: Minimum folio order (between 0-MAX_PAGECACHE_ORDER inclusive). + * + * The filesystem should call this function in its inode constructor to + * indicate which base size 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_min_order(struct address_space *mappi= ng, + unsigned int min) +{ + if (min > MAX_PAGECACHE_ORDER) + min =3D MAX_PAGECACHE_ORDER; + + mapping->flags =3D (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. + * @mapping: The address_space. * * The filesystem should call this function in its inode constructor to * indicate that the VFS can use large folios to cache the contents of @@ -357,7 +400,37 @@ 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_min_order(mapping, 0); +} + +static inline unsigned int mapping_max_folio_order(struct address_space *m= apping) +{ + return (mapping->flags & AS_FOLIO_ORDER_MAX_MASK) >> AS_FOLIO_ORDER_MAX; +} + +static inline unsigned int mapping_min_folio_order(struct address_space *m= apping) +{ + return (mapping->flags & AS_FOLIO_ORDER_MIN_MASK) >> AS_FOLIO_ORDER_MIN; +} + +static inline unsigned long mapping_min_folio_nrpages(struct address_space= *mapping) +{ + return 1UL << mapping_min_folio_order(mapping); +} + +/** + * mapping_align_start_index() - Align starting index based on the min + * folio order of the page cache. + * @mapping: The address_space. + * + * Ensure the index used is aligned to the minimum folio order when adding + * new folios to the page cache by rounding down to the nearest minimum + * folio number of pages. + */ +static inline pgoff_t mapping_align_start_index(struct address_space *mapp= ing, + pgoff_t index) +{ + return round_down(index, mapping_min_folio_nrpages(mapping)); } =20 /* @@ -367,7 +440,7 @@ static inline void mapping_set_large_folios(struct addr= ess_space *mapping) static inline bool mapping_large_folio_support(struct address_space *mappi= ng) { return IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && - test_bit(AS_LARGE_FOLIO_SUPPORT, &mapping->flags); + (mapping_max_folio_order(mapping) > 0); } =20 static inline int filemap_nr_thps(struct address_space *mapping) @@ -528,19 +601,6 @@ static inline void *detach_page_private(struct page *p= age) return folio_detach_private(page_folio(page)); } =20 -/* - * 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 --=20 2.43.0