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[PATCH] page migration cleanup: move fallback handling into special function

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Move the fallback code into a new fallback function and make the function
behave like any other migration function.  This requires retaking the lock if
pageout() drops it.

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 2006-06-23 02:03:33 -07:00 committed by Linus Torvalds
parent 2d1db3b117
commit 8351a6e478
1 changed files with 39 additions and 51 deletions
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90
mm/migrate.c
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@ -349,6 +349,42 @@ int buffer_migrate_page(struct address_space *mapping,
}
EXPORT_SYMBOL(buffer_migrate_page);
static int fallback_migrate_page(struct address_space *mapping,
struct page *newpage, struct page *page)
{
/*
* Default handling if a filesystem does not provide
* a migration function. We can only migrate clean
* pages so try to write out any dirty pages first.
*/
if (PageDirty(page)) {
switch (pageout(page, mapping)) {
case PAGE_KEEP:
case PAGE_ACTIVATE:
return -EAGAIN;
case PAGE_SUCCESS:
/* Relock since we lost the lock */
lock_page(page);
/* Must retry since page state may have changed */
return -EAGAIN;
case PAGE_CLEAN:
; /* try to migrate the page below */
}
}
/*
* Buffers may be managed in a filesystem specific way.
* We must have no buffers or drop them.
*/
if (page_has_buffers(page) &&
!try_to_release_page(page, GFP_KERNEL))
return -EAGAIN;
return migrate_page(mapping, newpage, page);
}
/*
* migrate_pages
*
@ -478,7 +514,7 @@ redo:
if (!mapping)
goto unlock_both;
if (mapping->a_ops->migratepage) {
if (mapping->a_ops->migratepage)
/*
* Most pages have a mapping and most filesystems
* should provide a migration function. Anonymous
@ -488,56 +524,8 @@ redo:
*/
rc = mapping->a_ops->migratepage(mapping,
newpage, page);
goto unlock_both;
}
/*
* Default handling if a filesystem does not provide
* a migration function. We can only migrate clean
* pages so try to write out any dirty pages first.
*/
if (PageDirty(page)) {
switch (pageout(page, mapping)) {
case PAGE_KEEP:
case PAGE_ACTIVATE:
goto unlock_both;
case PAGE_SUCCESS:
unlock_page(newpage);
goto next;
case PAGE_CLEAN:
; /* try to migrate the page below */
}
}
/*
* Buffers are managed in a filesystem specific way.
* We must have no buffers or drop them.
*/
if (!page_has_buffers(page) ||
try_to_release_page(page, GFP_KERNEL)) {
rc = migrate_page(mapping, newpage, page);
goto unlock_both;
}
/*
* On early passes with mapped pages simply
* retry. There may be a lock held for some
* buffers that may go away. Later
* swap them out.
*/
if (pass > 4) {
/*
* Persistently unable to drop buffers..... As a
* measure of last resort we fall back to
* swap_page().
*/
unlock_page(newpage);
newpage = NULL;
rc = swap_page(page);
goto next;
}
else
rc = fallback_migrate_page(mapping, newpage, page);
unlock_both:
unlock_page(newpage);