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[PATCH] AOP_TRUNCATED_PAGE victims in read_pages() belong in the LRU 

AOP_TRUNCATED_PAGE victims in read_pages() belong in the LRU

Nick Piggin rightly pointed out that the introduction of AOP_TRUNCATED_PAGE
to read_pages() was wrong to leave A_T_P victim pages in the page cache but
not put them in the LRU.  Failing to do so hid them from the VM.

A_T_P just means that the aop method unlocked the page rather than
performing IO.  It would be very rare that the page was truncated between
the unlock and testing A_T_P.  So we leave the pages in the LRU for likely
reuse soon rather than backing them back out of the page cache.  We do this
by matching the behaviour before the A_T_P introduction which added pages
to the LRU regardless of what ->readpage() did.

This doesn't include the unrelated cleanup in Nick's initial fix which
changed read_pages() to return void to match its only caller's behaviour of
ignoring errors.

Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Zach Brown <zach.brown@oracle.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Zach Brown 2006-06-25 05:46:46 -07:00 committed by Linus Torvalds
parent 09a9a45dc6
commit 9f1a3cfcff
1 changed files with 5 additions and 8 deletions
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13
mm/readahead.c
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@ -182,14 +182,11 @@ static int read_pages(struct address_space *mapping, struct file *filp,
list_del(&page->lru);
if (!add_to_page_cache(page, mapping,
page->index, GFP_KERNEL)) {
ret = mapping->a_ops->readpage(filp, page);
if (ret != AOP_TRUNCATED_PAGE) {
if (!pagevec_add(&lru_pvec, page))
__pagevec_lru_add(&lru_pvec);
continue;
} /* else fall through to release */
}
page_cache_release(page);
mapping->a_ops->readpage(filp, page);
if (!pagevec_add(&lru_pvec, page))
__pagevec_lru_add(&lru_pvec);
} else
page_cache_release(page);
}
pagevec_lru_add(&lru_pvec);
ret = 0;