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mm: put readahead pages in cache earlier

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When populating the page cache for readahead, mappings that use
->readpages must populate the page cache themselves as the pages are
passed on a linked list which would normally be used for the page
cache's LRU.  For mappings that use ->readpage or the upcoming
->readahead method, we can put the pages into the page cache as soon as
they're allocated, which solves a race between readahead and direct IO.
It also lets us remove the gfp argument from read_pages().

Use the new readahead_page() API to implement the repeated calls to
->readpage(), just like most filesystems will.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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: Dave Chinner <dchinner@redhat.com>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Gao Xiang <gaoxiang25@huawei.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: John Hubbard <jhubbard@nvidia.com>
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/20200414150233.24495-11-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2020-06-01 21:46:40 -07:00 committed by Linus Torvalds
parent ef8153b609
commit c1f6925e10
1 changed files with 28 additions and 18 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

40
mm/readahead.c
View file

@ -114,14 +114,14 @@ int read_cache_pages(struct address_space *mapping, struct list_head *pages,
EXPORT_SYMBOL(read_cache_pages);
static void read_pages(struct readahead_control *rac, struct list_head *pages,
gfp_t gfp)
bool skip_page)
{
const struct address_space_operations *aops = rac->mapping->a_ops;
struct page *page;
struct blk_plug plug;
unsigned page_idx;
if (!readahead_count(rac))
return;
goto out;
blk_start_plug(&plug);
@ -130,23 +130,23 @@ static void read_pages(struct readahead_control *rac, struct list_head *pages,
readahead_count(rac));
/* Clean up the remaining pages */
put_pages_list(pages);
goto out;
}
for (page_idx = 0; page_idx < readahead_count(rac); page_idx++) {
struct page *page = lru_to_page(pages);
list_del(&page->lru);
if (!add_to_page_cache_lru(page, rac->mapping, page->index,
gfp))
rac->_index += rac->_nr_pages;
rac->_nr_pages = 0;
} else {
while ((page = readahead_page(rac))) {
aops->readpage(rac->file, page);
put_page(page);
}
}
out:
blk_finish_plug(&plug);
BUG_ON(!list_empty(pages));
rac->_nr_pages = 0;
BUG_ON(readahead_count(rac));
out:
if (skip_page)
rac->_index++;
}
/*
@ -168,6 +168,7 @@ void __do_page_cache_readahead(struct address_space *mapping,
struct readahead_control rac = {
.mapping = mapping,
.file = filp,
._index = index,
};
unsigned long i;
@ -183,6 +184,8 @@ void __do_page_cache_readahead(struct address_space *mapping,
if (index + i > end_index)
break;
BUG_ON(index + i != rac._index + rac._nr_pages);
page = xa_load(&mapping->i_pages, index + i);
if (page && !xa_is_value(page)) {
/*
@ -190,15 +193,22 @@ void __do_page_cache_readahead(struct address_space *mapping,
* contiguous pages before continuing with the next
* batch.
*/
read_pages(&rac, &page_pool, gfp_mask);
read_pages(&rac, &page_pool, true);
continue;
}
page = __page_cache_alloc(gfp_mask);
if (!page)
break;
if (mapping->a_ops->readpages) {
page->index = index + i;
list_add(&page->lru, &page_pool);
} else if (add_to_page_cache_lru(page, mapping, index + i,
gfp_mask) < 0) {
put_page(page);
read_pages(&rac, &page_pool, true);
continue;
}
if (i == nr_to_read - lookahead_size)
SetPageReadahead(page);
rac._nr_pages++;
@ -209,7 +219,7 @@ void __do_page_cache_readahead(struct address_space *mapping,
* uptodate then the caller will launch readpage again, and
* will then handle the error.
*/
read_pages(&rac, &page_pool, gfp_mask);
read_pages(&rac, &page_pool, false);
}
/*