[v7,04/11] readahead: allocate folios with mapping_min_order in readahead

Message ID	20240607145902.1137853-5-kernel@pankajraghav.com (mailing list archive)
State	New
Headers	show Return-Path: <owner-linux-mm@kvack.org> From: "Pankaj Raghav (Samsung)" <kernel@pankajraghav.com> To: david@fromorbit.com, djwong@kernel.org, chandan.babu@oracle.com, brauner@kernel.org, akpm@linux-foundation.org, willy@infradead.org Cc: mcgrof@kernel.org, linux-mm@kvack.org, hare@suse.de, linux-kernel@vger.kernel.org, yang@os.amperecomputing.com, Zi Yan <zi.yan@sent.com>, linux-xfs@vger.kernel.org, p.raghav@samsung.com, linux-fsdevel@vger.kernel.org, kernel@pankajraghav.com, hch@lst.de, gost.dev@samsung.com, cl@os.amperecomputing.com, john.g.garry@oracle.com Subject: [PATCH v7 04/11] readahead: allocate folios with mapping_min_order in readahead Date: Fri, 7 Jun 2024 14:58:55 +0000 Message-ID: <20240607145902.1137853-5-kernel@pankajraghav.com> In-Reply-To: <20240607145902.1137853-1-kernel@pankajraghav.com> References: <20240607145902.1137853-1-kernel@pankajraghav.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org Precedence: bulk
Series	enable bs > ps in XFS \| expand [v7,00/11] enable bs > ps in XFS [v7,01/11] readahead: rework loop in page_cache_ra_unbounded() [v7,02/11] fs: Allow fine-grained control of folio sizes [v7,03/11] filemap: allocate mapping_min_order folios in the page cache [v7,04/11] readahead: allocate folios with mapping_min_order in readahead [v7,05/11] mm: split a folio in minimum folio order chunks [v7,06/11] filemap: cap PTE range to be created to allowed zero fill in folio_map_range() [v7,07/11] iomap: fix iomap_dio_zero() for fs bs > system page size [v7,08/11] xfs: use kvmalloc for xattr buffers [v7,09/11] xfs: expose block size in stat [v7,10/11] xfs: make the calculation generic in xfs_sb_validate_fsb_count() [v7,11/11] xfs: enable block size larger than page size support

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; } } }

[v7,04/11] readahead: allocate folios with mapping_min_order in readahead

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