Commit 9a42823a authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Linus Torvalds
Browse files

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().

Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
Reviewed-by: default avatarJohn Hubbard <jhubbard@nvidia.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarWilliam Kucharski <william.kucharski@oracle.com>
Cc: Chao Yu <yuchao0@huawei.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Gao Xiang <gaoxiang25@huawei.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Cc: Miklos Szeredi <mszeredi@redhat.com>
Link: http://lkml.kernel.org/r/20200414150233.24495-3-willy@infradead.org


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent cee9a0c4

mm/fadvise.c

+0 −4
Original line number Diff line number Diff line
@@ -104,10 +104,6 @@ int generic_fadvise(struct file *file, loff_t offset, loff_t len, int advice) 
		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:

mm/internal.h

+6 −6
Original line number Diff line number Diff line
@@ -49,19 +49,19 @@ void unmap_page_range(struct mmu_gather *tlb, 
			     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,

	__do_page_cache_readahead(mapping, filp,

			ra->start, ra->size, ra->async_size);

}

mm/readahead.c

+13 −18
Original line number Diff line number Diff line
@@ -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(struct address_space *mapping, 
	gfp_t gfp_mask = readahead_gfp_mask(mapping);



	if (isize == 0)

		goto out;

		return;



	end_index = ((isize - 1) >> PAGE_SHIFT);
@@ -211,23 +209,21 @@ 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;

}



/*

 * 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 address_space *mapping, struct file *filp, 
		offset += this_chunk;

		nr_to_read -= this_chunk;

	}

	return 0;

}



/*
@@ -378,8 +373,7 @@ 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,

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)
@@ -428,7 +422,7 @@ 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 +458,8 @@ 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 +484,7 @@ readit: 
		}

	}



	return ra_submit(ra, mapping, filp);

	ra_submit(ra, mapping, filp);

}



/**

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