ceph: check PG_Private flag before accessing page->private

[firefly-linux-kernel-4.4.55.git] / fs / ceph / addr.c

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 173b1d22e59b5a4bf8ed714f72b233cb70537468..8b67304e4b8079efe80eecd716fb1e98b5486842 100644 (file)
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -54,7 +54,12 @@
        (CONGESTION_ON_THRESH(congestion_kb) -                          \
         (CONGESTION_ON_THRESH(congestion_kb) >> 2))
 
-
+static inline struct ceph_snap_context *page_snap_context(struct page *page)
+{
+       if (PagePrivate(page))
+               return (void *)page->private;
+       return NULL;
+}
 
 /*
  * Dirty a page.  Optimistically adjust accounting, on the assumption
@@ -142,10 +147,9 @@ static void ceph_invalidatepage(struct page *page, unsigned long offset)
 {
        struct inode *inode;
        struct ceph_inode_info *ci;
-       struct ceph_snap_context *snapc = (void *)page->private;
+       struct ceph_snap_context *snapc = page_snap_context(page);
 
        BUG_ON(!PageLocked(page));
-       BUG_ON(!page->private);
        BUG_ON(!PagePrivate(page));
        BUG_ON(!page->mapping);
 
@@ -182,7 +186,6 @@ static int ceph_releasepage(struct page *page, gfp_t g)
        struct inode *inode = page->mapping ? page->mapping->host : NULL;
        dout("%p releasepage %p idx %lu\n", inode, page, page->index);
        WARN_ON(PageDirty(page));
-       WARN_ON(page->private);
        WARN_ON(PagePrivate(page));
        return 0;
 }
@@ -443,7 +446,7 @@ static int writepage_nounlock(struct page *page, struct writeback_control *wbc)
        osdc = &fsc->client->osdc;
 
        /* verify this is a writeable snap context */
-       snapc = (void *)page->private;
+       snapc = page_snap_context(page);
        if (snapc == NULL) {
                dout("writepage %p page %p not dirty?\n", inode, page);
                goto out;
@@ -451,7 +454,7 @@ static int writepage_nounlock(struct page *page, struct writeback_control *wbc)
        oldest = get_oldest_context(inode, &snap_size);
        if (snapc->seq > oldest->seq) {
                dout("writepage %p page %p snapc %p not writeable - noop\n",
-                    inode, page, (void *)page->private);
+                    inode, page, snapc);
                /* we should only noop if called by kswapd */
                WARN_ON((current->flags & PF_MEMALLOC) == 0);
                ceph_put_snap_context(oldest);
@@ -591,7 +594,7 @@ static void writepages_finish(struct ceph_osd_request *req,
                        clear_bdi_congested(&fsc->backing_dev_info,
                                            BLK_RW_ASYNC);
 
-               ceph_put_snap_context((void *)page->private);
+               ceph_put_snap_context(page_snap_context(page));
                page->private = 0;
                ClearPagePrivate(page);
                dout("unlocking %d %p\n", i, page);
@@ -795,7 +798,7 @@ get_more_pages:
                        }
 
                        /* only if matching snap context */
-                       pgsnapc = (void *)page->private;
+                       pgsnapc = page_snap_context(page);
                        if (pgsnapc->seq > snapc->seq) {
                                dout("page snapc %p %lld > oldest %p %lld\n",
                                     pgsnapc, pgsnapc->seq, snapc, snapc->seq);
@@ -984,7 +987,7 @@ retry_locked:
        BUG_ON(!ci->i_snap_realm);
        down_read(&mdsc->snap_rwsem);
        BUG_ON(!ci->i_snap_realm->cached_context);
-       snapc = (void *)page->private;
+       snapc = page_snap_context(page);
        if (snapc && snapc != ci->i_head_snapc) {
                /*
                 * this page is already dirty in another (older) snap