From: "Matthew Wilcox (Oracle)" <[email protected]> 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.
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]> --- mm/internal.h | 8 ++++---- mm/readahead.c | 24 ++++++++++-------------- 2 files changed, 14 insertions(+), 18 deletions(-) diff --git a/mm/internal.h b/mm/internal.h index 3cf20ab3ca01..f779f058118b 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -49,18 +49,18 @@ void unmap_page_range(struct mmu_gather *tlb, unsigned long addr, unsigned long end, struct zap_details *details); -extern unsigned int __do_page_cache_readahead(struct address_space *mapping, +extern void __do_page_cache_readahead(struct address_space *mapping, struct file *filp, pgoff_t offset, 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); } /* diff --git a/mm/readahead.c b/mm/readahead.c index 2fe72cd29b47..8ce46d69e6ae 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -149,10 +149,8 @@ static int read_pages(struct address_space *mapping, struct file *filp, * 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(struct address_space *mapping, gfp_t gfp_mask = readahead_gfp_mask(mapping); if (isize == 0) - goto out; + return; end_index = ((isize - 1) >> PAGE_SHIFT); @@ -211,8 +209,6 @@ unsigned int __do_page_cache_readahead(struct address_space *mapping, if (nr_pages) read_pages(mapping, filp, &page_pool, nr_pages, gfp_mask); BUG_ON(!list_empty(&page_pool)); -out: - return nr_pages; } /* @@ -378,11 +374,10 @@ static int try_context_readahead(struct address_space *mapping, /* * 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 +423,7 @@ ondemand_readahead(struct address_space *mapping, rcu_read_unlock(); if (!start || start - offset > max_pages) - return 0; + return; ra->start = start; ra->size = start - offset; /* old async_size */ @@ -464,7 +459,8 @@ ondemand_readahead(struct address_space *mapping, * 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 +485,7 @@ ondemand_readahead(struct address_space *mapping, } } - return ra_submit(ra, mapping, filp); + ra_submit(ra, mapping, filp); } /** -- 2.25.0
