[patch 15/59] Fix up CIFS for "test_clear_page_dirty()" removal

Chris Wright
2007-02-03T02:44:40Z

[-- Attachment #1: fix-up-cifs-for-test_clear_page_dirty-removal.patch --]
[-- Type: text/plain, Size: 2355 bytes --]

-stable review patch. If anyone has any objections, please let us know.
------------------

From: Linus Torvalds <torvalds@osdl.org>

Fix up CIFS for "test_clear_page_dirty()" removal

This also adds he required page "writeback" flag handling, that cifs
hasn't been doing and that the page dirty flag changes made obvious.

Acked-by: Steve French <smfltc@us.ibm.com>
Acked-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
---
This fixes a long term corruption bug when copying large files to a CIFS
mount. Thanks Linus!

---
fs/cifs/file.c | 26 +++++++++++++++++++++++---
1 file changed, 23 insertions(+), 3 deletions(-)

--- linux-2.6.19.2.orig/fs/cifs/file.c
+++ linux-2.6.19.2/fs/cifs/file.c
@@ -1244,14 +1244,21 @@ retry:
wait_on_page_writeback(page);

if (PageWriteback(page) ||
- !test_clear_page_dirty(page)) {
+ !clear_page_dirty_for_io(page)) {
unlock_page(page);
break;
}

+ /*
+ * This actually clears the dirty bit in the radix tree.
+ * See cifs_writepage() for more commentary.
+ */
+ set_page_writeback(page);
+
if (page_offset(page) >= mapping->host->i_size) {
done = 1;
unlock_page(page);
+ end_page_writeback(page);
break;
}

@@ -1315,6 +1322,7 @@ retry:
SetPageError(page);
kunmap(page);
unlock_page(page);
+ end_page_writeback(page);
page_cache_release(page);
}
if ((wbc->nr_to_write -= n_iov) <= 0)
@@ -1351,11 +1359,23 @@ static int cifs_writepage(struct page* p
if (!PageUptodate(page)) {
cFYI(1, ("ppw - page not up to date"));
}
-
+
+ /*
+ * Set the "writeback" flag, and clear "dirty" in the radix tree.
+ *
+ * A writepage() implementation always needs to do either this,
+ * or re-dirty the page with "redirty_page_for_writepage()" in
+ * the case of a failure.
+ *
+ * Just unlocking the page will cause the radix tree tag-bits
+ * to fail to update with the state of the page correctly.
+ */
+ set_page_writeback(page);
rc = cifs_partialpagewrite(page, 0, PAGE_CACHE_SIZE);
SetPageUptodate(page); /* BB add check for error and Clearuptodate? */
unlock_page(page);
- page_cache_release(page);
+ end_page_writeback(page);
+ page_cache_release(page);
FreeXid(xid);
return rc;
}

--