From patchwork Wed May 29 13:45:02 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Pankaj Raghav (Samsung)" X-Patchwork-Id: 13678919 Received: from mout-p-201.mailbox.org (mout-p-201.mailbox.org [80.241.56.171]) (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 89B8D3FBA5; Wed, 29 May 2024 13:45:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=80.241.56.171 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716990348; cv=none; b=mQ7kGty/CY4NZae780hdtaY6RTsBKg8wjWahlYEF3J8LRzwsc/lKEuqs8qhZiH3PUlGCEAEyURMDV8X0DCNVbz2kzSlj0fAniogp60K+ZAvCYoq82iWzJz4ev6Rx17MAVQewGbkGwlpcGtX5ZfPqRA1pbkR6GYZpvznnWTGro/E= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716990348; c=relaxed/simple; bh=cStaz4K0Q3P6YgfmwYpPr5zXAvaUylDPFNFAU07MLks=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=Am/3IHqA27mfNFX5sCSdQ+lQTjnSuyj72YaZD5FVE1+Q4BO8hzegR6j7gDouOFEBQYi1V3sAqq6pnQvXSGsQhVa8qcTzARxUyk015EN7anqLDGtfQ1YwbuMjvpbus1wFbQPip5W8QpubDY5fSM0DMgcYQRp8DMCIqScp4qkUXbQ= 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=T0Lrlfmv; arc=none smtp.client-ip=80.241.56.171 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="T0Lrlfmv" Received: from smtp2.mailbox.org (smtp2.mailbox.org [IPv6:2001:67c:2050:b231:465::2]) (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-201.mailbox.org (Postfix) with ESMTPS id 4Vq9cv680Kz9spR; Wed, 29 May 2024 15:45:35 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=pankajraghav.com; s=MBO0001; t=1716990335; 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=pUdfC/WKWCQctCsU2EgKroiARXKN//2pAERfC44xAGs=; b=T0LrlfmvkXeRbIR3+6/v8cSGJSLZyoRswYQNTCKEHVMiH7oMeWPQcJKoD1ZFu28aOgz76c /IJskjrRKDmRjdBnrKmDPnohP25Yb+Nk4ZcD7EmD3YKfSUwtQXHSmead6J+1Yq7OcPmCR3 mh2rB45o21CM8eVOz023SuA09Dsd1z6Q1YafkaB7hRhzCUHaUxQ/8r99BH2+1jtU2tr/g9 6+Z6Trj6r5EsKCNs8F+YKT44Z3++o27zlUp9OXvH56eS6eXx01tCaMsx+qhFE2mkZQvaaf hZskk6uFN9pIu+ysb51utULD6AY3exPLes+tMw+jURSijS3Awtx1HKv7kZmAjA== From: "Pankaj Raghav (Samsung)" To: david@fromorbit.com, chandan.babu@oracle.com, akpm@linux-foundation.org, brauner@kernel.org, willy@infradead.org, djwong@kernel.org Cc: linux-kernel@vger.kernel.org, hare@suse.de, john.g.garry@oracle.com, gost.dev@samsung.com, yang@os.amperecomputing.com, p.raghav@samsung.com, cl@os.amperecomputing.com, linux-xfs@vger.kernel.org, hch@lst.de, mcgrof@kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Subject: [PATCH v6 04/11] readahead: allocate folios with mapping_min_order in readahead Date: Wed, 29 May 2024 15:45:02 +0200 Message-Id: <20240529134509.120826-5-kernel@pankajraghav.com> In-Reply-To: <20240529134509.120826-1-kernel@pankajraghav.com> References: <20240529134509.120826-1-kernel@pankajraghav.com> Precedence: bulk X-Mailing-List: linux-xfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Rspamd-Queue-Id: 4Vq9cv680Kz9spR From: Pankaj Raghav page_cache_ra_unbounded() was allocating single pages (0 order folios) if there was no folio found in an index. Allocate mapping_min_order folios as we need to guarantee the minimum order if it is set. When read_pages() is triggered and if a page is already present, check for truncation and move the ractl->_index by mapping_min_nrpages if that folio was truncated. This is done to ensure we keep the alignment requirement while adding a folio to the page cache. page_cache_ra_order() tries to allocate folio to the page cache with a higher order if the index aligns with that order. Modify it so that the order does not go below the mapping_min_order requirement of the page cache. This function will do the right thing even if the new_order passed is less than the 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. readahead_expand() is called from readahead aops to extend the range of the readahead so this function can assume ractl->_index to be aligned with min_order. Signed-off-by: Pankaj Raghav Reviewed-by: Hannes Reinecke --- mm/readahead.c | 85 +++++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 71 insertions(+), 14 deletions(-) diff --git a/mm/readahead.c b/mm/readahead.c index da34b28da02c..389cd802da63 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -206,9 +206,10 @@ void page_cache_ra_unbounded(struct readahead_control *ractl, unsigned long nr_to_read, unsigned long lookahead_size) { struct address_space *mapping = ractl->mapping; - unsigned long index = readahead_index(ractl); + unsigned long ra_folio_index, index = readahead_index(ractl); gfp_t gfp_mask = readahead_gfp_mask(mapping); - unsigned long i = 0; + unsigned long mark, i = 0; + unsigned int min_nrpages = mapping_min_folio_nrpages(mapping); /* * Partway through the readahead operation, we will have added @@ -223,6 +224,22 @@ void page_cache_ra_unbounded(struct readahead_control *ractl, unsigned int nofs = memalloc_nofs_save(); filemap_invalidate_lock_shared(mapping); + index = mapping_align_start_index(mapping, index); + + /* + * As iterator `i` is aligned to min_nrpages, round_up the + * difference between nr_to_read and lookahead_size to mark the + * index that only has lookahead or "async_region" to set the + * readahead flag. + */ + ra_folio_index = round_up(readahead_index(ractl) + nr_to_read - lookahead_size, + min_nrpages); + mark = ra_folio_index - index; + if (index != readahead_index(ractl)) { + nr_to_read += readahead_index(ractl) - index; + ractl->_index = index; + } + /* * Preallocate as many pages as we will need. */ @@ -230,7 +247,9 @@ void page_cache_ra_unbounded(struct readahead_control *ractl, struct folio *folio = xa_load(&mapping->i_pages, index + i); int ret; + if (folio && !xa_is_value(folio)) { + long nr_pages = folio_nr_pages(folio); /* * Page already present? Kick off the current batch * of contiguous pages before continuing with the @@ -240,12 +259,24 @@ void page_cache_ra_unbounded(struct readahead_control *ractl, * not worth getting one just for that. */ read_pages(ractl); - ractl->_index += folio_nr_pages(folio); + + /* + * Move the ractl->_index by at least min_pages + * if the folio got truncated to respect the + * alignment constraint in the page cache. + * + */ + if (mapping != folio->mapping) + nr_pages = min_nrpages; + + VM_BUG_ON_FOLIO(nr_pages < min_nrpages, folio); + ractl->_index += nr_pages; i = ractl->_index + ractl->_nr_pages - index; continue; } - folio = filemap_alloc_folio(gfp_mask, 0); + folio = filemap_alloc_folio(gfp_mask, + mapping_min_folio_order(mapping)); if (!folio) break; @@ -255,11 +286,11 @@ void page_cache_ra_unbounded(struct readahead_control *ractl, if (ret == -ENOMEM) break; read_pages(ractl); - ractl->_index++; + ractl->_index += min_nrpages; i = ractl->_index + ractl->_nr_pages - index; continue; } - if (i == nr_to_read - lookahead_size) + if (i == mark) folio_set_readahead(folio); ractl->_workingset |= folio_test_workingset(folio); ractl->_nr_pages += folio_nr_pages(folio); @@ -493,13 +524,19 @@ void page_cache_ra_order(struct readahead_control *ractl, { struct address_space *mapping = ractl->mapping; pgoff_t index = readahead_index(ractl); + unsigned int min_order = mapping_min_folio_order(mapping); pgoff_t limit = (i_size_read(mapping->host) - 1) >> PAGE_SHIFT; pgoff_t mark = index + ra->size - ra->async_size; unsigned int nofs; int err = 0; gfp_t gfp = readahead_gfp_mask(mapping); + unsigned int min_ra_size = max(4, mapping_min_folio_nrpages(mapping)); - if (!mapping_large_folio_support(mapping) || ra->size < 4) + /* + * Fallback when size < min_nrpages as each folio should be + * at least min_nrpages anyway. + */ + if (!mapping_large_folio_support(mapping) || ra->size < min_ra_size) goto fallback; limit = min(limit, index + ra->size - 1); @@ -508,11 +545,20 @@ void page_cache_ra_order(struct readahead_control *ractl, new_order += 2; new_order = min(mapping_max_folio_order(mapping), new_order); new_order = min_t(unsigned int, new_order, ilog2(ra->size)); + new_order = max(new_order, min_order); } /* See comment in page_cache_ra_unbounded() */ nofs = memalloc_nofs_save(); filemap_invalidate_lock_shared(mapping); + /* + * If the new_order is greater than min_order and index is + * already aligned to new_order, then this will be noop as index + * aligned to new_order should also be aligned to min_order. + */ + ractl->_index = mapping_align_start_index(mapping, index); + index = readahead_index(ractl); + while (index <= limit) { unsigned int order = new_order; @@ -520,7 +566,7 @@ void page_cache_ra_order(struct readahead_control *ractl, if (index & ((1UL << order) - 1)) order = __ffs(index); /* Don't allocate pages past EOF */ - while (index + (1UL << order) - 1 > limit) + while (order > min_order && index + (1UL << order) - 1 > limit) order--; err = ra_alloc_folio(ractl, index, mark, order, gfp); if (err) @@ -784,8 +830,15 @@ void readahead_expand(struct readahead_control *ractl, struct file_ra_state *ra = ractl->ra; pgoff_t new_index, new_nr_pages; gfp_t gfp_mask = readahead_gfp_mask(mapping); + unsigned long min_nrpages = mapping_min_folio_nrpages(mapping); + unsigned int min_order = mapping_min_folio_order(mapping); new_index = new_start / PAGE_SIZE; + /* + * Readahead code should have aligned the ractl->_index to + * min_nrpages before calling readahead aops. + */ + VM_BUG_ON(!IS_ALIGNED(ractl->_index, min_nrpages)); /* Expand the leading edge downwards */ while (ractl->_index > new_index) { @@ -795,9 +848,11 @@ void readahead_expand(struct readahead_control *ractl, if (folio && !xa_is_value(folio)) return; /* Folio apparently present */ - folio = filemap_alloc_folio(gfp_mask, 0); + folio = filemap_alloc_folio(gfp_mask, min_order); if (!folio) return; + + index = mapping_align_start_index(mapping, index); if (filemap_add_folio(mapping, folio, index, gfp_mask) < 0) { folio_put(folio); return; @@ -807,7 +862,7 @@ void readahead_expand(struct readahead_control *ractl, ractl->_workingset = true; psi_memstall_enter(&ractl->_pflags); } - ractl->_nr_pages++; + ractl->_nr_pages += min_nrpages; ractl->_index = folio->index; } @@ -822,9 +877,11 @@ void readahead_expand(struct readahead_control *ractl, if (folio && !xa_is_value(folio)) return; /* Folio apparently present */ - folio = filemap_alloc_folio(gfp_mask, 0); + folio = filemap_alloc_folio(gfp_mask, min_order); if (!folio) return; + + index = mapping_align_start_index(mapping, index); if (filemap_add_folio(mapping, folio, index, gfp_mask) < 0) { folio_put(folio); return; @@ -834,10 +891,10 @@ void readahead_expand(struct readahead_control *ractl, ractl->_workingset = true; psi_memstall_enter(&ractl->_pflags); } - ractl->_nr_pages++; + ractl->_nr_pages += min_nrpages; if (ra) { - ra->size++; - ra->async_size++; + ra->size += min_nrpages; + ra->async_size += min_nrpages; } } }