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[PATCH] SwapMig: Switch error handling in migrate_pages to use -Exx 

Use -Exxx instead of numeric return codes and cleanup the code in
migrate_pages() using -Exx error codes.

Consolidate successful migration handling

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Christoph Lameter 2006-01-08 01:00:55 -08:00 committed by Linus Torvalds
parent d498471133
commit d0d963281c
1 changed files with 34 additions and 22 deletions
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56
mm/vmscan.c
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@ -606,10 +606,6 @@ int putback_lru_pages(struct list_head *l)
/*
* swapout a single page
* page is locked upon entry, unlocked on exit
*
* return codes:
* 0 = complete
* 1 = retry
*/
static int swap_page(struct page *page)
{
@ -650,7 +646,7 @@ static int swap_page(struct page *page)
unlock_page(page);
retry:
return 1;
return -EAGAIN;
}
/*
* migrate_pages
@ -669,6 +665,8 @@ static int swap_page(struct page *page)
* is only swapping out pages and never touches the second
* list. The direct migration patchset
* extends this function to avoid the use of swap.
*
* Return: Number of pages not migrated when "to" ran empty.
*/
int migrate_pages(struct list_head *from, struct list_head *to,
struct list_head *moved, struct list_head *failed)
@ -679,6 +677,7 @@ int migrate_pages(struct list_head *from, struct list_head *to,
struct page *page;
struct page *page2;
int swapwrite = current->flags & PF_SWAPWRITE;
int rc;
if (!swapwrite)
current->flags |= PF_SWAPWRITE;
@ -689,22 +688,23 @@ int migrate_pages(struct list_head *from, struct list_head *to,
list_for_each_entry_safe(page, page2, from, lru) {
cond_resched();
if (page_count(page) == 1) {
rc = 0;
if (page_count(page) == 1)
/* page was freed from under us. So we are done. */
list_move(&page->lru, moved);
continue;
}
goto next;
/*
* Skip locked pages during the first two passes to give the
* functions holding the lock time to release the page. Later we
* use lock_page() to have a higher chance of acquiring the
* lock.
*/
rc = -EAGAIN;
if (pass > 2)
lock_page(page);
else
if (TestSetPageLocked(page))
goto retry_later;
goto next;
/*
* Only wait on writeback if we have already done a pass where
@ -713,18 +713,19 @@ int migrate_pages(struct list_head *from, struct list_head *to,
if (pass > 0) {
wait_on_page_writeback(page);
} else {
if (PageWriteback(page)) {
unlock_page(page);
goto retry_later;
}
if (PageWriteback(page))
goto unlock_page;
}
/*
* Anonymous pages must have swap cache references otherwise
* the information contained in the page maps cannot be
* preserved.
*/
if (PageAnon(page) && !PageSwapCache(page)) {
if (!add_to_swap(page, GFP_KERNEL)) {
unlock_page(page);
list_move(&page->lru, failed);
nr_failed++;
continue;
rc = -ENOMEM;
goto unlock_page;
}
}
@ -732,12 +733,23 @@ int migrate_pages(struct list_head *from, struct list_head *to,
* Page is properly locked and writeback is complete.
* Try to migrate the page.
*/
if (!swap_page(page)) {
rc = swap_page(page);
goto next;
unlock_page:
unlock_page(page);
next:
if (rc == -EAGAIN) {
retry++;
} else if (rc) {
/* Permanent failure */
list_move(&page->lru, failed);
nr_failed++;
} else {
/* Success */
list_move(&page->lru, moved);
continue;
}
retry_later:
retry++;
}
if (retry && pass++ < 10)
goto redo;