ceph: page still marked private_2

Previous patch that allowed us to cleanup most of the issues with pages marked
as private_2 when calling ceph_readpages. However, there seams to be a case in
the error case clean up in start read that still trigers this from time to
time. I've only seen this one a couple times.

BUG: Bad page state in process petabucket  pfn:335b82
page:ffffea000cd6e080 count:0 mapcount:0 mapping:          (null) index:0x0
page flags: 0x200000000001000(private_2)
Call Trace:
 [<ffffffff81563442>] dump_stack+0x46/0x58
 [<ffffffff8112c7f7>] bad_page+0xc7/0x120
 [<ffffffff8112cd9e>] free_pages_prepare+0x10e/0x120
 [<ffffffff8112e580>] free_hot_cold_page+0x40/0x160
 [<ffffffff81132427>] __put_single_page+0x27/0x30
 [<ffffffff81132d95>] put_page+0x25/0x40
 [<ffffffffa02cb409>] ceph_readpages+0x2e9/0x6f0 [ceph]
 [<ffffffff811313cf>] __do_page_cache_readahead+0x1af/0x260

Signed-off-by: Milosz Tanski <milosz@adfin.com>
Signed-off-by: Sage Weil <sage@inktank.com>

fs/ceph/addr.c

@@ -336,6 +336,7 @@ static int start_read(struct inode *inode, struct list_head *page_list, int max)
 		     page->index);
 		if (add_to_page_cache_lru(page, &inode->i_data, page->index,
 					  GFP_NOFS)) {
+			ceph_fscache_uncache_page(inode, page);
 			page_cache_release(page);
 			dout("start_read %p add_to_page_cache failed %p\n",
 			     inode, page);

fs/ceph/cache.h

@@ -51,6 +51,13 @@ static inline void ceph_fscache_invalidate(struct inode *inode)
 	fscache_invalidate(ceph_inode(inode)->fscache);
 }
 
+static inline void ceph_fscache_uncache_page(struct inode *inode,
+					     struct page *page)
+{
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	return fscache_uncache_page(ci->fscache, page);
+}
+
 static inline int ceph_release_fscache_page(struct page *page, gfp_t gfp)
 {
 	struct inode* inode = page->mapping->host;
@@ -94,7 +101,8 @@ static inline void ceph_fscache_register_inode_cookie(struct ceph_fs_client* par
 {
 }
 
-static inline void ceph_fscache_unregister_inode_cookie(struct ceph_inode_info* ci)
+static inline void ceph_fscache_uncache_page(struct inode *inode,
+					     struct page *pages)
 {
 }
 
@@ -126,6 +134,10 @@ static inline void ceph_invalidate_fscache_page(struct inode *inode,
 {
 }
 
+static inline void ceph_fscache_unregister_inode_cookie(struct ceph_inode_info* ci)
+{
+}
+
 static inline int ceph_release_fscache_page(struct page *page, gfp_t gfp)
 {
 	return 1;