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Wed, 13 Mar 2024 18:03:20 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=pankajraghav.com; s=MBO0001; t=1710349400; 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=RU7wAkeEZDBqdQxVOpHCiR4r3AW1LNpG/Tc03yCcuTY=; b=TTj6XlQFpuWaG2HRYwVUmyL+mGDOj1YyE4BzeSzFG1uBTNOYHvqLSLJTAqTzOXnojbUFav VaI6Qsori+supnIjfxd7QOIIRBt1r3AjdYofmkNSsGr1IzJ+kCMctOkAAwm7VlS4HYxEwd xhBIKghw4OfU+qFZghRdae1Y3kRqk8ielVKILzxzoDayVYCCt3MRCU1hTX/PN4sZvgQ33s ldT65trmEXqfRbC8rb0GhMPrB26/1wbc37xM1ESEazL9aNIsjbMNJiTV0XGU5MF3Oqr4YQ tKChz4zQjWYPgbXBOzZwEHxjNui6cK8PvepNc7H9MPPB3lVOeKaxX9IUrPkHog== From: "Pankaj Raghav (Samsung)" To: willy@infradead.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org Cc: gost.dev@samsung.com, chandan.babu@oracle.com, hare@suse.de, mcgrof@kernel.org, djwong@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, david@fromorbit.com, akpm@linux-foundation.org, Pankaj Raghav Subject: [PATCH v3 05/11] readahead: allocate folios with mapping_min_order in readahead Date: Wed, 13 Mar 2024 18:02:47 +0100 Message-ID: <20240313170253.2324812-6-kernel@pankajraghav.com> In-Reply-To: <20240313170253.2324812-1-kernel@pankajraghav.com> References: <20240313170253.2324812-1-kernel@pankajraghav.com> MIME-Version: 1.0 X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 17037C0029 X-Stat-Signature: cc756aguesihc5sw5tahrzdpk3swxxft X-HE-Tag: 1710349403-932481 X-HE-Meta: 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 DocCW7OT pe0YxocWLzCSuNgquElRVAU0O/UCSiPH666+WUvhg+kuGvbnbIQxoUyosSYt2Q7czaxyNE6guSR7qfrDNABKfZ7QMKooO5MMgr6locjjxD/MhT/shNW6KvRl7NrCNiOgeAZ3eEvKE2Ccez64= 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 min_order requirement of the page cache. 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 | 86 ++++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 72 insertions(+), 14 deletions(-) diff --git a/mm/readahead.c b/mm/readahead.c index 37b938f4b54f..650834c033f0 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); @@ -505,9 +542,19 @@ void page_cache_ra_order(struct readahead_control *ractl, new_order = MAX_PAGECACHE_ORDER; while ((1 << new_order) > ra->size) new_order--; + if (new_order < min_order) + 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; @@ -515,7 +562,7 @@ 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) @@ -778,8 +825,15 @@ 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) { @@ -789,9 +843,11 @@ 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; @@ -801,7 +857,7 @@ 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; } @@ -816,9 +872,11 @@ 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; @@ -828,10 +886,10 @@ 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; } } }