From: Matthew Wilcox <willy@infradead.org> To: Andrew Morton <akpm@linux-foundation.org> Cc: linux-xfs@vger.kernel.org, William Kucharski <william.kucharski@oracle.com>, Eric Biggers <ebiggers@google.com>, linux-kernel@vger.kernel.org, "Matthew Wilcox \(Oracle\)" <willy@infradead.org>, linux-f2fs-devel@lists.sourceforge.net, cluster-devel@redhat.com, linux-mm@kvack.org, ocfs2-devel@oss.oracle.com, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-erofs@lists.ozlabs.org, Christoph Hellwig <hch@lst.de>, linux-btrfs@vger.kernel.org Subject: [PATCH v10 13/25] mm: Add page_cache_readahead_unbounded Date: Mon, 23 Mar 2020 13:22:47 -0700 Message-ID: <20200323202259.13363-14-willy@infradead.org> (raw) In-Reply-To: <20200323202259.13363-1-willy@infradead.org> From: "Matthew Wilcox (Oracle)" <willy@infradead.org> 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) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: William Kucharski <william.kucharski@oracle.com> Reviewed-by: Eric Biggers <ebiggers@google.com> Tested-by: Eric Biggers <ebiggers@google.com> --- fs/ext4/verity.c | 35 ++------------------- fs/f2fs/data.c | 2 +- fs/f2fs/f2fs.h | 3 -- fs/f2fs/verity.c | 35 ++------------------- include/linux/pagemap.h | 3 ++ mm/readahead.c | 68 ++++++++++++++++++++++++++++------------- 6 files changed, 55 insertions(+), 91 deletions(-) diff --git a/fs/ext4/verity.c b/fs/ext4/verity.c index dc5ec724d889..dec1244dd062 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_unbounded(inode->i_mapping, NULL, + index, num_ra_pages, 0); page = read_mapping_page(inode->i_mapping, index, NULL); } return page; diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index dbde309349d0..adc4766782e1 100644 --- a/fs/f2fs/data.c +++ b/fs/f2fs/data.c @@ -2148,7 +2148,7 @@ int f2fs_read_multi_pages(struct compress_ctx *cc, struct bio **bio_ret, * use ->readpage() or do the necessary surgery to decouple ->readpages() * from read-ahead. */ -int f2fs_mpage_readpages(struct address_space *mapping, +static int f2fs_mpage_readpages(struct address_space *mapping, struct list_head *pages, struct page *page, unsigned nr_pages, bool is_readahead) { diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index 3e727a6af08e..d59b715d7870 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -3369,9 +3369,6 @@ int f2fs_reserve_new_block(struct dnode_of_data *dn); int f2fs_get_block(struct dnode_of_data *dn, pgoff_t index); int f2fs_preallocate_blocks(struct kiocb *iocb, struct iov_iter *from); int f2fs_reserve_block(struct dnode_of_data *dn, pgoff_t index); -int f2fs_mpage_readpages(struct address_space *mapping, - struct list_head *pages, struct page *page, - unsigned nr_pages, bool is_readahead); struct page *f2fs_get_read_data_page(struct inode *inode, pgoff_t index, int op_flags, bool for_write); struct page *f2fs_find_data_page(struct inode *inode, pgoff_t index); diff --git a/fs/f2fs/verity.c b/fs/f2fs/verity.c index d7d430a6f130..865c9fb774fb 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_unbounded(inode->i_mapping, NULL, + index, 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 89fd6a62bfa5..84e1bd68fda4 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -619,6 +619,9 @@ void page_cache_sync_readahead(struct address_space *, struct file_ra_state *, void page_cache_async_readahead(struct address_space *, struct file_ra_state *, struct file *, struct page *, pgoff_t index, unsigned long req_count); +void page_cache_readahead_unbounded(struct address_space *, struct file *, + pgoff_t index, unsigned long nr_to_read, + unsigned long lookahead_count); /* * Like add_to_page_cache_locked, but used to add newly allocated pages: diff --git a/mm/readahead.c b/mm/readahead.c index 998fdd23c0b1..ae231a5312cb 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -156,37 +156,34 @@ static void read_pages(struct readahead_control *rac, struct list_head *pages, rac->_index++; } -/* - * __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_unbounded - Start unchecked readahead. + * @mapping: File address space. + * @file: This instance of the open file; used for authentication. + * @index: First 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 beyond a file's stated i_size. This is almost certainly + * not the function you want to call. Use 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 index, unsigned long nr_to_read, +void page_cache_readahead_unbounded(struct address_space *mapping, + struct file *file, pgoff_t index, unsigned long nr_to_read, unsigned long lookahead_size) { - struct inode *inode = mapping->host; LIST_HEAD(page_pool); - loff_t isize = i_size_read(inode); gfp_t gfp_mask = readahead_gfp_mask(mapping); struct readahead_control rac = { .mapping = mapping, - .file = filp, + .file = file, ._index = index, }; unsigned long i; - pgoff_t end_index; /* The last page we want to read */ - - if (isize == 0) - return; - - end_index = (isize - 1) >> PAGE_SHIFT; - if (index > end_index) - return; - /* Don't read past the page containing the last byte of the file */ - if (nr_to_read > end_index - index) - nr_to_read = end_index - index + 1; /* * Preallocate as many pages as we will need. @@ -230,6 +227,35 @@ void __do_page_cache_readahead(struct address_space *mapping, */ read_pages(&rac, &page_pool, false); } +EXPORT_SYMBOL_GPL(page_cache_readahead_unbounded); + +/* + * __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 index, unsigned long nr_to_read, + unsigned long lookahead_size) +{ + struct inode *inode = mapping->host; + loff_t isize = i_size_read(inode); + pgoff_t end_index; /* The last page we want to read */ + + if (isize == 0) + return; + + end_index = (isize - 1) >> PAGE_SHIFT; + if (index > end_index) + return; + /* Don't read past the page containing the last byte of the file */ + if (nr_to_read > end_index - index) + nr_to_read = end_index - index + 1; + + page_cache_readahead_unbounded(mapping, file, index, nr_to_read, + lookahead_size); +} /* * Chunk the readahead into 2 megabyte units, so that we don't pin too much -- 2.25.1
next prev parent reply index Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-03-23 20:22 [PATCH v10 00/25] Change readahead API Matthew Wilcox 2020-03-23 20:22 ` [PATCH v10 01/25] mm: Move readahead prototypes from mm.h Matthew Wilcox 2020-03-23 20:22 ` [PATCH v10 02/25] mm: Return void from various readahead functions Matthew Wilcox 2020-03-23 20:22 ` [PATCH v10 03/25] mm: Ignore return value of ->readpages Matthew Wilcox 2020-03-23 20:22 ` [PATCH v10 04/25] mm: Move readahead nr_pages check into read_pages Matthew Wilcox 2020-03-23 20:22 ` [PATCH v10 05/25] mm: Add new readahead_control API Matthew Wilcox 2020-03-23 20:22 ` [PATCH v10 06/25] mm: Use readahead_control to pass arguments Matthew Wilcox 2020-03-23 20:22 ` [PATCH v10 07/25] mm: Rename various 'offset' parameters to 'index' Matthew Wilcox 2020-03-23 20:22 ` [PATCH v10 08/25] mm: rename readahead loop variable to 'i' Matthew Wilcox 2020-03-23 20:22 ` [PATCH v10 09/25] mm: Remove 'page_offset' from readahead loop Matthew Wilcox 2020-03-23 20:22 ` [PATCH v10 10/25] mm: Put readahead pages in cache earlier Matthew Wilcox 2020-03-23 20:22 ` [PATCH v10 11/25] mm: Add readahead address space operation Matthew Wilcox 2020-03-23 20:22 ` [PATCH v10 12/25] mm: Move end_index check out of readahead loop Matthew Wilcox 2020-03-23 20:49 ` Eric Biggers 2020-03-24 8:40 ` Christoph Hellwig 2020-03-23 20:22 ` Matthew Wilcox [this message] 2020-03-23 20:22 ` [PATCH v10 14/25] mm: Document why we don't set PageReadahead Matthew Wilcox 2020-03-23 20:22 ` [PATCH v10 15/25] mm: Use memalloc_nofs_save in readahead path Matthew Wilcox 2020-03-23 20:22 ` [PATCH v10 16/25] fs: Convert mpage_readpages to mpage_readahead Matthew Wilcox 2020-03-23 20:22 ` [PATCH v10 17/25] btrfs: Convert from readpages to readahead Matthew Wilcox 2020-03-26 16:53 ` David Sterba 2020-03-23 20:22 ` [PATCH v10 18/25] erofs: Convert uncompressed files " Matthew Wilcox 2020-03-23 20:22 ` [PATCH v10 19/25] erofs: Convert compressed " Matthew Wilcox 2020-03-23 20:22 ` [PATCH v10 20/25] ext4: Convert " Matthew Wilcox 2020-03-23 20:22 ` [PATCH v10 21/25] ext4: Pass the inode to ext4_mpage_readpages Matthew Wilcox 2020-03-23 20:22 ` [PATCH v10 22/25] f2fs: Convert from readpages to readahead Matthew Wilcox 2020-03-23 20:22 ` [PATCH v10 23/25] f2fs: Pass the inode to f2fs_mpage_readpages Matthew Wilcox 2020-03-23 20:22 ` [PATCH v10 24/25] fuse: Convert from readpages to readahead Matthew Wilcox 2020-03-25 9:42 ` Miklos Szeredi 2020-03-25 12:02 ` Matthew Wilcox 2020-03-25 14:43 ` Miklos Szeredi 2020-03-25 15:32 ` Matthew Wilcox 2020-03-25 15:54 ` Miklos Szeredi 2020-03-23 20:22 ` [PATCH v10 25/25] iomap: " Matthew Wilcox
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