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mm: move end_index check out of readahead loop

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By reducing nr_to_read, we can eliminate this check from inside the loop.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Cc: Chao Yu <yuchao0@huawei.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Dave Chinner <dchinner@redhat.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/20200414150233.24495-13-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2020-06-01 21:46:47 -07:00 committed by Linus Torvalds
parent 8151b4c8be
commit b0f31d78cb
1 changed files with 8 additions and 6 deletions
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14
mm/readahead.c
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@ -167,8 +167,6 @@ void __do_page_cache_readahead(struct address_space *mapping,
unsigned long lookahead_size)
{
struct inode *inode = mapping->host;
struct page *page;
unsigned long end_index; /* The last page we want to read */
LIST_HEAD(page_pool);
loff_t isize = i_size_read(inode);
gfp_t gfp_mask = readahead_gfp_mask(mapping);
@ -178,22 +176,26 @@ void __do_page_cache_readahead(struct address_space *mapping,
._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);
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.
*/
for (i = 0; i < nr_to_read; i++) {
if (index + i > end_index)
break;
struct page *page = xa_load(&mapping->i_pages, index + i);
BUG_ON(index + i != rac._index + rac._nr_pages);
page = xa_load(&mapping->i_pages, index + i);
if (page && !xa_is_value(page)) {
/*
* Page already present? Kick off the current batch of