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do_wp_page: clarify dirty_page handling 

Reorganize the code so that dirty pages are handled closer to the place
that makes them dirty (handling write fault into shared, writable VMAs).
No behavior changes.

Signed-off-by: Michel Lespinasse <walken@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Kosaki Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Theodore Tso <tytso@google.com>
Cc: Michael Rubin <mrubin@google.com>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Michel Lespinasse 2011-01-13 15:46:08 -08:00 committed by Linus Torvalds
parent b009c024ff
commit 72ddc8f722
1 changed files with 38 additions and 34 deletions
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72
mm/memory.c
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@ -2229,8 +2229,45 @@ reuse:
entry = maybe_mkwrite(pte_mkdirty(entry), vma);
if (ptep_set_access_flags(vma, address, page_table, entry,1))
update_mmu_cache(vma, address, page_table);
pte_unmap_unlock(page_table, ptl);
ret |= VM_FAULT_WRITE;
goto unlock;
if (!dirty_page)
return ret;
/*
* Yes, Virginia, this is actually required to prevent a race
* with clear_page_dirty_for_io() from clearing the page dirty
* bit after it clear all dirty ptes, but before a racing
* do_wp_page installs a dirty pte.
*
* do_no_page is protected similarly.
*/
if (!page_mkwrite) {
wait_on_page_locked(dirty_page);
set_page_dirty_balance(dirty_page, page_mkwrite);
}
put_page(dirty_page);
if (page_mkwrite) {
struct address_space *mapping = dirty_page->mapping;
set_page_dirty(dirty_page);
unlock_page(dirty_page);
page_cache_release(dirty_page);
if (mapping) {
/*
* Some device drivers do not set page.mapping
* but still dirty their pages
*/
balance_dirty_pages_ratelimited(mapping);
}
}
/* file_update_time outside page_lock */
if (vma->vm_file)
file_update_time(vma->vm_file);
return ret;
}
/*
@ -2336,39 +2373,6 @@ gotten:
page_cache_release(old_page);
unlock:
pte_unmap_unlock(page_table, ptl);
if (dirty_page) {
/*
* Yes, Virginia, this is actually required to prevent a race
* with clear_page_dirty_for_io() from clearing the page dirty
* bit after it clear all dirty ptes, but before a racing
* do_wp_page installs a dirty pte.
*
* do_no_page is protected similarly.
*/
if (!page_mkwrite) {
wait_on_page_locked(dirty_page);
set_page_dirty_balance(dirty_page, page_mkwrite);
}
put_page(dirty_page);
if (page_mkwrite) {
struct address_space *mapping = dirty_page->mapping;
set_page_dirty(dirty_page);
unlock_page(dirty_page);
page_cache_release(dirty_page);
if (mapping) {
/*
* Some device drivers do not set page.mapping
* but still dirty their pages
*/
balance_dirty_pages_ratelimited(mapping);
}
}
/* file_update_time outside page_lock */
if (vma->vm_file)
file_update_time(vma->vm_file);
}
return ret;
oom_free_new:
page_cache_release(new_page);