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Thu, 25 Apr 2024 13:38:06 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=pankajraghav.com; s=MBO0001; t=1714045086; 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=LAt6S24Vjnx4CNZrkFkZzKX+VLk83S8Eni5970rjRTI=; b=fj653PzCK3e+p9Gi6sS7fVwaC7HJREI+ZN7gDJ8DRp9GQn4/iRpUudp5IQ089pQcYJxbz1 /EDDC9NEgIhX4pJKl/ADI6wPB9avUNHefq7wQXCJ9yT/RlO7eAjBoTreh+PB0qjrpKKZN7 Kza+MpB2PJDkPo92dEM/1ObNcT2ZPWI3utuH1dYkToN/RrciSCPpWGNsu6D2hNbtvn0oV8 5PUcrDOmGnzm9Gzb6T79Z/FKgYLW0dLx1qET3cD9aCqt4l+O66qvBSEvKLIor7Qe2t3Yvz jK3OfPI3H9Uf+NKG0Rtt0XNtzzIDTgwBCe3M98OHPaeeWPPV6hVHPVKjoO3tsA== From: "Pankaj Raghav (Samsung)" To: willy@infradead.org, djwong@kernel.org, brauner@kernel.org, david@fromorbit.com, chandan.babu@oracle.com, akpm@linux-foundation.org Cc: linux-fsdevel@vger.kernel.org, hare@suse.de, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-xfs@vger.kernel.org, mcgrof@kernel.org, gost.dev@samsung.com, p.raghav@samsung.com Subject: [PATCH v4 04/11] readahead: allocate folios with mapping_min_order in readahead Date: Thu, 25 Apr 2024 13:37:39 +0200 Message-Id: <20240425113746.335530-5-kernel@pankajraghav.com> In-Reply-To: <20240425113746.335530-1-kernel@pankajraghav.com> References: <20240425113746.335530-1-kernel@pankajraghav.com> MIME-Version: 1.0 X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: C317280008 X-Stat-Signature: 7wxcoq8f7zx6j9kz8j3c7xoxpas4ipi4 X-Rspam-User: X-HE-Tag: 1714045089-382782 X-HE-Meta: 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 L2DX1+3x 133ae/0qT3+thyk9qCzs1/l2CIAYvxYC/XIrc+1Ep3Q/ZQV+9qTwcndlnOsFSIq6UfL2XwqF1Ze3Iy/e/jk1XCY76g/4kTHiGJKTYBJ1eRhtFN1+ND98ffHGOr1cwiy7z2A3SvioENH9hB3We06QzCop8j7q+SXH5r2LdxsxRVdWvdfeHS1Ijq3xbMs72AnYq3NQA4pSLtYVXO9qCPzBzqYWI3PDa/ZrQS3YVKq+wlb0QRY9/WFLwQ2XGMjLZgRBzno4IdDIHd0Xd//4= 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: 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 --- mm/readahead.c | 85 +++++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 71 insertions(+), 14 deletions(-) diff --git a/mm/readahead.c b/mm/readahead.c index 2361634a84fd..9c193185a836 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 index = readahead_index(ractl), ra_folio_index; gfp_t gfp_mask = readahead_gfp_mask(mapping); - unsigned long i = 0; + unsigned long i = 0, mark; + 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. */ @@ -230,6 +247,8 @@ void page_cache_ra_unbounded(struct readahead_control *ractl, struct folio *folio = xa_load(&mapping->i_pages, index + i); 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 @@ -239,23 +258,35 @@ 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; if (filemap_add_folio(mapping, folio, index + i, gfp_mask) < 0) { folio_put(folio); 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); @@ -489,12 +520,18 @@ 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; 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); @@ -503,9 +540,18 @@ void page_cache_ra_order(struct readahead_control *ractl, new_order += 2; new_order = min_t(unsigned int, MAX_PAGECACHE_ORDER, new_order); new_order = min_t(unsigned int, new_order, ilog2(ra->size)); + new_order = max(new_order, min_order); } 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; @@ -513,7 +559,7 @@ 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) @@ -776,8 +822,15 @@ 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) { @@ -787,9 +840,11 @@ 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; @@ -799,7 +854,7 @@ 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; } @@ -814,9 +869,11 @@ 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; @@ -826,10 +883,10 @@ 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; } } }