ceph: fix readpage from fscache

ceph_readpage() unlocks page prematurely prematurely in the case
that page is reading from fscache. Caller of readpage expects that
page is uptodate when it get unlocked. So page shoule get locked
by completion callback of fscache_read_or_alloc_pages()

Cc: stable@vger.kernel.org # 4.1+, needs backporting for < 4.7
Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

1 files changed, 3 insertions, 9 deletions

diff --git a/fs/ceph/cache.c b/fs/ceph/cache.c
index fd1172823f86..337f88673ed9 100644
--- a/fs/ceph/cache.c
+++ b/fs/ceph/cache.c
@@ -297,13 +297,7 @@ void ceph_fscache_file_set_cookie(struct inode *inode, struct file *filp)
         }
 }
 
-static void ceph_vfs_readpage_complete(struct page *page, void *data, int error)
-{
-        if (!error)
-                SetPageUptodate(page);
-}
-
-static void ceph_vfs_readpage_complete_unlock(struct page *page, void *data, int error)
+static void ceph_readpage_from_fscache_complete(struct page *page, void *data, int error)
 {
         if (!error)
                 SetPageUptodate(page);
@@ -331,7 +325,7 @@ int ceph_readpage_from_fscache(struct inode *inode, struct page *page)
                 return -ENOBUFS;
 
         ret = fscache_read_or_alloc_page(ci->fscache, page,
-                                         ceph_vfs_readpage_complete, NULL,
+                                         ceph_readpage_from_fscache_complete, NULL,
                                          GFP_KERNEL);
 
         switch (ret) {
@@ -360,7 +354,7 @@ int ceph_readpages_from_fscache(struct inode *inode,
                 return -ENOBUFS;
 
         ret = fscache_read_or_alloc_pages(ci->fscache, mapping, pages, nr_pages,
-                                          ceph_vfs_readpage_complete_unlock,
+                                          ceph_readpage_from_fscache_complete,
                                           NULL, mapping_gfp_mask(mapping));
 
         switch (ret) {