[PATCH]: ufs: ufs_get_locked_patch race fix

Evgeniy Dushistov
2006-07-31T12:49:09Z

As discussed earlier:
http://lkml.org/lkml/2006/6/28/136
this patch fixes such issue:
`ufs_get_locked_page' takes page from cache
after that `vmtruncate' takes page and deletes it from cache
`ufs_get_locked_page' locks page, and reports about EIO error.

Also because of find_lock_page always return valid page or NULL,
we have no need check it if page not NULL.

Signed-off-by: Evgeniy Dushistov <dushistov@mail.ru>

---

Index: linux-2.6.18-rc2-mm1/fs/ufs/util.c
===================================================================
--- linux-2.6.18-rc2-mm1.orig/fs/ufs/util.c
+++ linux-2.6.18-rc2-mm1/fs/ufs/util.c
@@ -257,6 +257,7 @@ try_again:
page = read_cache_page(mapping, index,
(filler_t*)mapping->a_ops->readpage,
NULL);
+
if (IS_ERR(page)) {
printk(KERN_ERR "ufs_change_blocknr: "
"read_cache_page error: ino %lu, index: %lu\n",
@@ -266,6 +267,13 @@ try_again:

lock_page(page);

+ if (unlikely(page->mapping != mapping ||
+ page->index != index)) {
+ unlock_page(page);
+ page_cache_release(page);
+ goto try_again;
+ }
+
if (!PageUptodate(page) || PageError(page)) {
unlock_page(page);
page_cache_release(page);
@@ -275,15 +283,8 @@ try_again:
mapping->host->i_ino, index);

page = ERR_PTR(-EIO);
- goto out;
}
}
-
- if (unlikely(!page->mapping || !page_has_buffers(page))) {
- unlock_page(page);
- page_cache_release(page);
- goto try_again;/*we really need these buffers*/
- }
out:
return page;
}

--
/Evgeniy