ufs_get_locked_page(): make sure we have buffer_heads

callers rely upon that, but find_lock_page() racing with attempt of
page eviction by memory pressure might have left us with
	* try_to_free_buffers() successfully done
	* __remove_mapping() failed, leaving the page in our mapping
	* find_lock_page() returning an uptodate page with no
buffer_heads attached.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 8 insertions, 9 deletions

diff --git a/fs/ufs/util.c b/fs/ufs/util.c
index f41ad0a6106f..02497a492eb2 100644
--- a/fs/ufs/util.c
+++ b/fs/ufs/util.c
@@ -243,9 +243,8 @@ ufs_set_inode_dev(struct super_block *sb, struct ufs_inode_info *ufsi, dev_t dev
 struct page *ufs_get_locked_page(struct address_space *mapping,
                                  pgoff_t index)
 {
-        struct page *page;
-
-        page = find_lock_page(mapping, index);
+        struct inode *inode = mapping->host;
+        struct page *page = find_lock_page(mapping, index);
         if (!page) {
                 page = read_mapping_page(mapping, index, NULL);
 
@@ -253,7 +252,7 @@ struct page *ufs_get_locked_page(struct address_space *mapping,
                         printk(KERN_ERR "ufs_change_blocknr: "
                                "read_mapping_page error: ino %lu, index: %lu\n",
                                mapping->host->i_ino, index);
-                        goto out;
+                        return page;
                 }
 
                 lock_page(page);
@@ -262,8 +261,7 @@ struct page *ufs_get_locked_page(struct address_space *mapping,
                         /* Truncate got there first */
                         unlock_page(page);
                         put_page(page);
-                        page = NULL;
-                        goto out;
+                        return NULL;
                 }
 
                 if (!PageUptodate(page) || PageError(page)) {
@@ -272,11 +270,12 @@ struct page *ufs_get_locked_page(struct address_space *mapping,
 
                         printk(KERN_ERR "ufs_change_blocknr: "
                                "can not read page: ino %lu, index: %lu\n",
-                               mapping->host->i_ino, index);
+                               inode->i_ino, index);
 
-                        page = ERR_PTR(-EIO);
+                        return ERR_PTR(-EIO);
                 }
         }
-out:
+        if (!page_has_buffers(page))
+                create_empty_buffers(page, 1 << inode->i_blkbits, 0);
         return page;
 }