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authorEvgeniy Dushistov <dushistov@mail.ru>2006-08-05 12:13:55 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-08-06 08:57:46 -0700
commit1fb32b7bd8203d0175649a75ede3ee7634d6a941 (patch)
tree1c0b7bd06835ce37dc2fc18a95fe3fe22c2ce556
parente91467ecd1ef381377fd327c0ded922835ec52ab (diff)
downloadlinux-1fb32b7bd8203d0175649a75ede3ee7634d6a941.tar.gz
[PATCH] ufs: ufs_get_locked_page() race fix
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 to check it if page not NULL.

Signed-off-by: Evgeniy Dushistov <dushistov@mail.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--fs/ufs/util.c15
1 files changed, 8 insertions, 7 deletions
diff --git a/fs/ufs/util.c b/fs/ufs/util.c
index 337cf2c46d10..005d6815adf5 100644
--- a/fs/ufs/util.c
+++ b/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 == NULL)) {
+			/* Truncate got there first */
+			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;
 }