This patch replaces cancel_dirty_page() with a helper function
account_page_cleaned() which only updates counters. It's called from
truncate_complete_page() and from try_to_free_buffers() (hack for ext3).
Page is locked in both cases, page-lock protects against concurrent
dirtiers: see commit
2d6d7f982846 ("mm: protect set_page_dirty() from
ongoing truncation").
Delete_from_page_cache() shouldn't be called for dirty pages, they must
be handled by caller (either written or truncated). This patch treats
final dirty accounting fixup at the end of __delete_from_page_cache() as
a debug check and adds WARN_ON_ONCE() around it. If something removes
dirty pages without proper handling that might be a bug and unwritten
data might be lost.
Hugetlbfs has no dirty pages accounting, ClearPageDirty() is enough
here.
cancel_dirty_page() in nfs_wb_page_cancel() is redundant. This is
helper for nfs_invalidate_page() and it's called only in case complete
invalidation.
The mess was started in v2.6.20 after commits
46d2277c796f ("Clean up
and make try_to_free_buffers() not race with dirty pages") and
3e67c0987d75 ("truncate: clear page dirtiness before running
try_to_free_buffers()") first was reverted right in v2.6.20 in commit
ecdfc9787fe5 ("Resurrect 'try_to_free_buffers()' VM hackery"), second in
v2.6.25 commit
a2b345642f53 ("Fix dirty page accounting leak with ext3
data=journal").
Custom fixes were introduced between these points. NFS in v2.6.23, commit
1b3b4a1a2deb ("NFS: Fix a write request leak in nfs_invalidate_page()").
Kludge in __delete_from_page_cache() in v2.6.24, commit
3a6927906f1b ("Do
dirty page accounting when removing a page from the page cache"). Since
v2.6.25 all of them are redundant.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Tejun Heo <tj@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
if (PagePrivate(page))
page->mapping->a_ops->invalidatepage(page, 0, PAGE_CACHE_SIZE);
- cancel_dirty_page(page, PAGE_SIZE);
+ if (TestClearPageDirty(page))
+ account_page_cleaned(page, mapping);
+
ClearPageMappedToDisk(page);
ll_delete_from_page_cache(page);
}
* to synchronise against __set_page_dirty_buffers and prevent the
* dirty bit from being lost.
*/
- if (ret)
- cancel_dirty_page(page, PAGE_CACHE_SIZE);
+ if (ret && TestClearPageDirty(page))
+ account_page_cleaned(page, mapping);
spin_unlock(&mapping->private_lock);
out:
if (buffers_to_free) {
static void truncate_huge_page(struct page *page)
{
- cancel_dirty_page(page, /* No IO accounting for huge pages? */0);
+ ClearPageDirty(page);
ClearPageUptodate(page);
delete_from_page_cache(page);
}
* request from the inode / page_private pointer and
* release it */
nfs_inode_remove_request(req);
- /*
- * In case nfs_inode_remove_request has marked the
- * page as being dirty
- */
- cancel_dirty_page(page, PAGE_CACHE_SIZE);
nfs_unlock_and_release_request(req);
}
int redirty_page_for_writepage(struct writeback_control *wbc,
struct page *page);
void account_page_dirtied(struct page *page, struct address_space *mapping);
+void account_page_cleaned(struct page *page, struct address_space *mapping);
int set_page_dirty(struct page *page);
int set_page_dirty_lock(struct page *page);
int clear_page_dirty_for_io(struct page *page);
+
int get_cmdline(struct task_struct *task, char *buffer, int buflen);
/* Is the vma a continuation of the stack vma above it? */
CLEARPAGEFLAG(Uptodate, uptodate)
-extern void cancel_dirty_page(struct page *page, unsigned int account_size);
-
int test_clear_page_writeback(struct page *page);
int __test_set_page_writeback(struct page *page, bool keep_write);
BUG_ON(page_mapped(page));
/*
- * Some filesystems seem to re-dirty the page even after
- * the VM has canceled the dirty bit (eg ext3 journaling).
+ * At this point page must be either written or cleaned by truncate.
+ * Dirty page here signals a bug and loss of unwritten data.
*
- * Fix it up by doing a final dirty accounting check after
- * having removed the page entirely.
+ * This fixes dirty accounting after removing the page entirely but
+ * leaves PageDirty set: it has no effect for truncated page and
+ * anyway will be cleared before returning page into buddy allocator.
*/
- if (PageDirty(page) && mapping_cap_account_dirty(mapping)) {
- dec_zone_page_state(page, NR_FILE_DIRTY);
- dec_bdi_stat(inode_to_bdi(mapping->host), BDI_RECLAIMABLE);
- }
+ if (WARN_ON_ONCE(PageDirty(page)))
+ account_page_cleaned(page, mapping);
}
/**
}
EXPORT_SYMBOL(account_page_dirtied);
+/*
+ * Helper function for deaccounting dirty page without writeback.
+ *
+ * Doing this should *normally* only ever be done when a page
+ * is truncated, and is not actually mapped anywhere at all. However,
+ * fs/buffer.c does this when it notices that somebody has cleaned
+ * out all the buffers on a page without actually doing it through
+ * the VM. Can you say "ext3 is horribly ugly"? Thought you could.
+ */
+void account_page_cleaned(struct page *page, struct address_space *mapping)
+{
+ if (mapping_cap_account_dirty(mapping)) {
+ dec_zone_page_state(page, NR_FILE_DIRTY);
+ dec_bdi_stat(inode_to_bdi(mapping->host), BDI_RECLAIMABLE);
+ task_io_account_cancelled_write(PAGE_CACHE_SIZE);
+ }
+}
+EXPORT_SYMBOL(account_page_cleaned);
+
/*
* For address_spaces which do not use buffers. Just tag the page as dirty in
* its radix tree.
(*invalidatepage)(page, offset, length);
}
-/*
- * This cancels just the dirty bit on the kernel page itself, it
- * does NOT actually remove dirty bits on any mmap's that may be
- * around. It also leaves the page tagged dirty, so any sync
- * activity will still find it on the dirty lists, and in particular,
- * clear_page_dirty_for_io() will still look at the dirty bits in
- * the VM.
- *
- * Doing this should *normally* only ever be done when a page
- * is truncated, and is not actually mapped anywhere at all. However,
- * fs/buffer.c does this when it notices that somebody has cleaned
- * out all the buffers on a page without actually doing it through
- * the VM. Can you say "ext3 is horribly ugly"? Tought you could.
- */
-void cancel_dirty_page(struct page *page, unsigned int account_size)
-{
- if (TestClearPageDirty(page)) {
- struct address_space *mapping = page->mapping;
- if (mapping && mapping_cap_account_dirty(mapping)) {
- dec_zone_page_state(page, NR_FILE_DIRTY);
- dec_bdi_stat(inode_to_bdi(mapping->host),
- BDI_RECLAIMABLE);
- if (account_size)
- task_io_account_cancelled_write(account_size);
- }
- }
-}
-EXPORT_SYMBOL(cancel_dirty_page);
-
/*
* If truncate cannot remove the fs-private metadata from the page, the page
* becomes orphaned. It will be left on the LRU and may even be mapped into
if (page_has_private(page))
do_invalidatepage(page, 0, PAGE_CACHE_SIZE);
- cancel_dirty_page(page, PAGE_CACHE_SIZE);
+ /*
+ * Some filesystems seem to re-dirty the page even after
+ * the VM has canceled the dirty bit (eg ext3 journaling).
+ * Hence dirty accounting check is placed after invalidation.
+ */
+ if (TestClearPageDirty(page))
+ account_page_cleaned(page, mapping);
ClearPageMappedToDisk(page);
delete_from_page_cache(page);
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