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: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: William 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: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2020-06-01 21:46:10 -07:00 committed by Linus Torvalds
parent cee9a0c4e8
commit 9a42823a10
3 changed files with 19 additions and 28 deletions

View File

@ -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:

View File

@ -49,20 +49,20 @@ 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,
ra->start, ra->size, ra->async_size);
__do_page_cache_readahead(mapping, filp,
ra->start, ra->size, ra->async_size);
}
/**

View File

@ -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;
}
/*
@ -378,11 +373,10 @@ 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 +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);
}
/**