From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: + mm-return-void-from-various-readahead-functions.patch added to -mm tree Date: Tue, 14 Apr 2020 18:17:26 -0700 Message-ID: <20200415011726.mjktEQkCX%akpm@linux-foundation.org> References: <20200412004155.1a8f4e081b4e03ef5903abb5@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.29.99]:50760 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389151AbgDOBR2 (ORCPT ); Tue, 14 Apr 2020 21:17:28 -0400 In-Reply-To: <20200412004155.1a8f4e081b4e03ef5903abb5@linux-foundation.org> Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: darrick.wong@oracle.com, dchinner@redhat.com, ebiggers@google.com, gaoxiang25@huawei.com, hch@lst.de, jaegeuk@kernel.org, jhubbard@nvidia.com, joseph.qi@linux.alibaba.com, junxiao.bi@oracle.com, mhocko@suse.com, mm-commits@vger.kernel.org, william.kucharski@oracle.com, willy@infradead.org, xiyou.wangcong@gmail.com, yuchao0@huawei.com, ziy@nvidia.com The patch titled Subject: mm: return void from various readahead functions has been added to the -mm tree. Its filename is mm-return-void-from-various-readahead-functions.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/mm-return-void-from-various-readahead-functions.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/mm-return-void-from-various-readahead-functions.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: "Matthew Wilcox (Oracle)" Subject: mm: return void from various readahead functions ondemand_readahead has two callers, neither of which use the return value. That means that both ra_submit and __do_page_cache_readahead() can return void, and we don't need to worry that a present page in the readahead window causes us to return a smaller nr_pages than we ought to have. Similarly, no caller uses the return value from force_page_cache_readahead(). Link: http://lkml.kernel.org/r/20200414150233.24495-3-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Dave Chinner Reviewed-by: John Hubbard Reviewed-by: Christoph Hellwig Reviewed-by: William Kucharski Cc: Chao Yu Cc: Cong Wang Cc: Darrick J. Wong Cc: Eric Biggers Cc: Gao Xiang Cc: Jaegeuk Kim Cc: Joseph Qi Cc: Junxiao Bi Cc: Michal Hocko Cc: Zi Yan Signed-off-by: Andrew Morton --- mm/fadvise.c | 4 ---- mm/internal.h | 12 ++++++------ mm/readahead.c | 31 +++++++++++++------------------ 3 files changed, 19 insertions(+), 28 deletions(-) --- a/mm/fadvise.c~mm-return-void-from-various-readahead-functions +++ a/mm/fadvise.c @@ -104,10 +104,6 @@ int generic_fadvise(struct file *file, l if (!nrpages) nrpages = ~0UL; - /* - * Ignore return value because fadvise() shall return - * success even if filesystem can't retrieve a hint, - */ force_page_cache_readahead(mapping, file, start_index, nrpages); break; case POSIX_FADV_NOREUSE: --- a/mm/internal.h~mm-return-void-from-various-readahead-functions +++ a/mm/internal.h @@ -49,20 +49,20 @@ void unmap_page_range(struct mmu_gather unsigned long addr, unsigned long end, struct zap_details *details); -int force_page_cache_readahead(struct address_space *, struct file *, +void force_page_cache_readahead(struct address_space *, struct file *, pgoff_t index, unsigned long nr_to_read); -extern unsigned int __do_page_cache_readahead(struct address_space *mapping, - struct file *filp, pgoff_t offset, unsigned long nr_to_read, +void __do_page_cache_readahead(struct address_space *, struct file *, + pgoff_t index, unsigned long nr_to_read, unsigned long lookahead_size); /* * Submit IO for the read-ahead request in file_ra_state. */ -static inline unsigned long ra_submit(struct file_ra_state *ra, +static inline void ra_submit(struct file_ra_state *ra, struct address_space *mapping, struct file *filp) { - return __do_page_cache_readahead(mapping, filp, - ra->start, ra->size, ra->async_size); + __do_page_cache_readahead(mapping, filp, + ra->start, ra->size, ra->async_size); } /** --- a/mm/readahead.c~mm-return-void-from-various-readahead-functions +++ a/mm/readahead.c @@ -149,10 +149,8 @@ out: * 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. - * - * Returns the number of pages requested, or the maximum amount of I/O allowed. */ -unsigned int __do_page_cache_readahead(struct address_space *mapping, +void __do_page_cache_readahead(struct address_space *mapping, struct file *filp, pgoff_t offset, unsigned long nr_to_read, unsigned long lookahead_size) { @@ -166,7 +164,7 @@ unsigned int __do_page_cache_readahead(s gfp_t gfp_mask = readahead_gfp_mask(mapping); if (isize == 0) - goto out; + return; end_index = ((isize - 1) >> PAGE_SHIFT); @@ -211,23 +209,21 @@ unsigned int __do_page_cache_readahead(s if (nr_pages) read_pages(mapping, filp, &page_pool, nr_pages, gfp_mask); BUG_ON(!list_empty(&page_pool)); -out: - return nr_pages; } /* * Chunk the readahead into 2 megabyte units, so that we don't pin too much * memory at once. */ -int force_page_cache_readahead(struct address_space *mapping, struct file *filp, - pgoff_t offset, unsigned long nr_to_read) +void force_page_cache_readahead(struct address_space *mapping, + struct file *filp, pgoff_t offset, unsigned long nr_to_read) { struct backing_dev_info *bdi = inode_to_bdi(mapping->host); struct file_ra_state *ra = &filp->f_ra; unsigned long max_pages; if (unlikely(!mapping->a_ops->readpage && !mapping->a_ops->readpages)) - return -EINVAL; + return; /* * If the request exceeds the readahead window, allow the read to @@ -245,7 +241,6 @@ int force_page_cache_readahead(struct ad offset += this_chunk; nr_to_read -= this_chunk; } - return 0; } /* @@ -378,11 +373,10 @@ static int try_context_readahead(struct /* * A minimal readahead algorithm for trivial sequential/random reads. */ -static unsigned long -ondemand_readahead(struct address_space *mapping, - struct file_ra_state *ra, struct file *filp, - bool hit_readahead_marker, pgoff_t offset, - unsigned long req_size) +static void ondemand_readahead(struct address_space *mapping, + struct file_ra_state *ra, struct file *filp, + bool hit_readahead_marker, pgoff_t offset, + unsigned long req_size) { struct backing_dev_info *bdi = inode_to_bdi(mapping->host); unsigned long max_pages = ra->ra_pages; @@ -428,7 +422,7 @@ ondemand_readahead(struct address_space rcu_read_unlock(); if (!start || start - offset > max_pages) - return 0; + return; ra->start = start; ra->size = start - offset; /* old async_size */ @@ -464,7 +458,8 @@ ondemand_readahead(struct address_space * standalone, small random read * Read as is, and do not pollute the readahead state. */ - return __do_page_cache_readahead(mapping, filp, offset, req_size, 0); + __do_page_cache_readahead(mapping, filp, offset, req_size, 0); + return; initial_readahead: ra->start = offset; @@ -489,7 +484,7 @@ readit: } } - return ra_submit(ra, mapping, filp); + ra_submit(ra, mapping, filp); } /** _ Patches currently in -mm which might be from willy@infradead.org are mm-move-readahead-prototypes-from-mmh.patch mm-return-void-from-various-readahead-functions.patch mm-ignore-return-value-of-readpages.patch mm-move-readahead-nr_pages-check-into-read_pages.patch mm-add-new-readahead_control-api.patch mm-use-readahead_control-to-pass-arguments.patch mm-rename-various-offset-parameters-to-index.patch mm-rename-readahead-loop-variable-to-i.patch mm-remove-page_offset-from-readahead-loop.patch mm-put-readahead-pages-in-cache-earlier.patch mm-add-readahead-address-space-operation.patch mm-move-end_index-check-out-of-readahead-loop.patch mm-add-page_cache_readahead_unbounded.patch mm-document-why-we-dont-set-pagereadahead.patch mm-use-memalloc_nofs_save-in-readahead-path.patch fs-convert-mpage_readpages-to-mpage_readahead.patch btrfs-convert-from-readpages-to-readahead.patch erofs-convert-uncompressed-files-from-readpages-to-readahead.patch erofs-convert-compressed-files-from-readpages-to-readahead.patch ext4-convert-from-readpages-to-readahead.patch ext4-pass-the-inode-to-ext4_mpage_readpages.patch f2fs-convert-from-readpages-to-readahead.patch f2fs-pass-the-inode-to-f2fs_mpage_readpages.patch fuse-convert-from-readpages-to-readahead.patch iomap-convert-from-readpages-to-readahead.patch