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Received: from willy by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1j3lPL-0005AO-RE; Mon, 17 Feb 2020 18:46:15 +0000 From: Matthew Wilcox To: linux-fsdevel@vger.kernel.org Date: Mon, 17 Feb 2020 10:45:56 -0800 Message-Id: <20200217184613.19668-16-willy@infradead.org> X-Mailer: git-send-email 2.21.1 In-Reply-To: <20200217184613.19668-1-willy@infradead.org> References: <20200217184613.19668-1-willy@infradead.org> MIME-Version: 1.0 X-Headers-End: 1j3lPb-006PP3-R1 Subject: [f2fs-dev] [PATCH v6 09/19] mm: Add page_cache_readahead_limit X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org, "Matthew Wilcox \(Oracle\)" , linux-f2fs-devel@lists.sourceforge.net, cluster-devel@redhat.com, linux-mm@kvack.org, ocfs2-devel@oss.oracle.com, linux-ext4@vger.kernel.org, linux-erofs@lists.ozlabs.org, linux-btrfs@vger.kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net From: "Matthew Wilcox (Oracle)" ext4 and f2fs have duplicated the guts of the readahead code so they can read past i_size. Instead, separate out the guts of the readahead code so they can call it directly. Signed-off-by: Matthew Wilcox (Oracle) --- fs/ext4/verity.c | 35 ++--------------------- fs/f2fs/verity.c | 35 ++--------------------- include/linux/pagemap.h | 4 +++ mm/readahead.c | 61 +++++++++++++++++++++++++++++------------ 4 files changed, 52 insertions(+), 83 deletions(-) diff --git a/fs/ext4/verity.c b/fs/ext4/verity.c index dc5ec724d889..f6e0bf05933e 100644 --- a/fs/ext4/verity.c +++ b/fs/ext4/verity.c @@ -342,37 +342,6 @@ static int ext4_get_verity_descriptor(struct inode *inode, void *buf, return desc_size; } -/* - * Prefetch some pages from the file's Merkle tree. - * - * This is basically a stripped-down version of __do_page_cache_readahead() - * which works on pages past i_size. - */ -static void ext4_merkle_tree_readahead(struct address_space *mapping, - pgoff_t start_index, unsigned long count) -{ - LIST_HEAD(pages); - unsigned int nr_pages = 0; - struct page *page; - pgoff_t index; - struct blk_plug plug; - - for (index = start_index; index < start_index + count; index++) { - page = xa_load(&mapping->i_pages, index); - if (!page || xa_is_value(page)) { - page = __page_cache_alloc(readahead_gfp_mask(mapping)); - if (!page) - break; - page->index = index; - list_add(&page->lru, &pages); - nr_pages++; - } - } - blk_start_plug(&plug); - ext4_mpage_readpages(mapping, &pages, NULL, nr_pages, true); - blk_finish_plug(&plug); -} - static struct page *ext4_read_merkle_tree_page(struct inode *inode, pgoff_t index, unsigned long num_ra_pages) @@ -386,8 +355,8 @@ static struct page *ext4_read_merkle_tree_page(struct inode *inode, if (page) put_page(page); else if (num_ra_pages > 1) - ext4_merkle_tree_readahead(inode->i_mapping, index, - num_ra_pages); + page_cache_readahead_limit(inode->i_mapping, NULL, + index, LONG_MAX, num_ra_pages, 0); page = read_mapping_page(inode->i_mapping, index, NULL); } return page; diff --git a/fs/f2fs/verity.c b/fs/f2fs/verity.c index d7d430a6f130..71a3e36721fa 100644 --- a/fs/f2fs/verity.c +++ b/fs/f2fs/verity.c @@ -222,37 +222,6 @@ static int f2fs_get_verity_descriptor(struct inode *inode, void *buf, return size; } -/* - * Prefetch some pages from the file's Merkle tree. - * - * This is basically a stripped-down version of __do_page_cache_readahead() - * which works on pages past i_size. - */ -static void f2fs_merkle_tree_readahead(struct address_space *mapping, - pgoff_t start_index, unsigned long count) -{ - LIST_HEAD(pages); - unsigned int nr_pages = 0; - struct page *page; - pgoff_t index; - struct blk_plug plug; - - for (index = start_index; index < start_index + count; index++) { - page = xa_load(&mapping->i_pages, index); - if (!page || xa_is_value(page)) { - page = __page_cache_alloc(readahead_gfp_mask(mapping)); - if (!page) - break; - page->index = index; - list_add(&page->lru, &pages); - nr_pages++; - } - } - blk_start_plug(&plug); - f2fs_mpage_readpages(mapping, &pages, NULL, nr_pages, true); - blk_finish_plug(&plug); -} - static struct page *f2fs_read_merkle_tree_page(struct inode *inode, pgoff_t index, unsigned long num_ra_pages) @@ -266,8 +235,8 @@ static struct page *f2fs_read_merkle_tree_page(struct inode *inode, if (page) put_page(page); else if (num_ra_pages > 1) - f2fs_merkle_tree_readahead(inode->i_mapping, index, - num_ra_pages); + page_cache_readahead_limit(inode->i_mapping, NULL, + index, LONG_MAX, num_ra_pages, 0); page = read_mapping_page(inode->i_mapping, index, NULL); } return page; diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index bd4291f78f41..4f36c06d064d 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -389,6 +389,10 @@ extern struct page * read_cache_page_gfp(struct address_space *mapping, pgoff_t index, gfp_t gfp_mask); extern int read_cache_pages(struct address_space *mapping, struct list_head *pages, filler_t *filler, void *data); +void page_cache_readahead_limit(struct address_space *mapping, + struct file *file, pgoff_t offset, pgoff_t end_index, + unsigned long nr_to_read, unsigned long lookahead_size); + static inline struct page *read_mapping_page(struct address_space *mapping, pgoff_t index, void *data) diff --git a/mm/readahead.c b/mm/readahead.c index 975ff5e387be..94d499cfb657 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -142,35 +142,38 @@ static void read_pages(struct readahead_control *rac, struct list_head *pages) blk_finish_plug(&plug); } -/* - * __do_page_cache_readahead() actually reads a chunk of disk. It allocates - * the pages first, then submits them for I/O. This avoids the very bad - * behaviour which would occur if page allocations are causing VM writeback. - * We really don't want to intermingle reads and writes like that. +/** + * page_cache_readahead_limit - Start readahead beyond a file's i_size. + * @mapping: File address space. + * @file: This instance of the open file; used for authentication. + * @offset: First page index to read. + * @end_index: The maximum page index to read. + * @nr_to_read: The number of pages to read. + * @lookahead_size: Where to start the next readahead. + * + * This function is for filesystems to call when they want to start + * readahead potentially beyond a file's stated i_size. If you want + * to start readahead on a normal file, you probably want to call + * page_cache_async_readahead() or page_cache_sync_readahead() instead. + * + * Context: File is referenced by caller. Mutexes may be held by caller. + * May sleep, but will not reenter filesystem to reclaim memory. */ -void __do_page_cache_readahead(struct address_space *mapping, - struct file *filp, pgoff_t offset, unsigned long nr_to_read, - unsigned long lookahead_size) +void page_cache_readahead_limit(struct address_space *mapping, + struct file *file, pgoff_t offset, pgoff_t end_index, + unsigned long nr_to_read, unsigned long lookahead_size) { - struct inode *inode = mapping->host; - unsigned long end_index; /* The last page we want to read */ LIST_HEAD(page_pool); unsigned long i; - loff_t isize = i_size_read(inode); gfp_t gfp_mask = readahead_gfp_mask(mapping); bool use_list = mapping->a_ops->readpages; struct readahead_control rac = { .mapping = mapping, - .file = filp, + .file = file, ._start = offset, ._nr_pages = 0, }; - if (isize == 0) - return; - - end_index = ((isize - 1) >> PAGE_SHIFT); - /* * Preallocate as many pages as we will need. */ @@ -225,6 +228,30 @@ void __do_page_cache_readahead(struct address_space *mapping, read_pages(&rac, &page_pool); BUG_ON(!list_empty(&page_pool)); } +EXPORT_SYMBOL_GPL(page_cache_readahead_limit); + +/* + * __do_page_cache_readahead() actually reads a chunk of disk. It allocates + * the pages first, then submits them for I/O. This avoids the very bad + * behaviour which would occur if page allocations are causing VM writeback. + * We really don't want to intermingle reads and writes like that. + */ +void __do_page_cache_readahead(struct address_space *mapping, + struct file *file, pgoff_t offset, unsigned long nr_to_read, + unsigned long lookahead_size) +{ + struct inode *inode = mapping->host; + unsigned long end_index; /* The last page we want to read */ + loff_t isize = i_size_read(inode); + + if (isize == 0) + return; + + end_index = ((isize - 1) >> PAGE_SHIFT); + + page_cache_readahead_limit(mapping, file, offset, end_index, + nr_to_read, lookahead_size); +} /* * Chunk the readahead into 2 megabyte units, so that we don't pin too much -- 2.25.0 _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel