pstore: gracefully handle NULL pstore_info functions

If a pstore backend doesn't want to support various portions of the
pstore interface, it can just leave those functions NULL instead of
creating no-op stubs.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>

2 files changed, 5 insertions, 4 deletions

diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index 379a02dc121..b3b426edb2f 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -80,7 +80,8 @@ static int pstore_unlink(struct inode *dir, struct dentry *dentry)
 {
         struct pstore_private *p = dentry->d_inode->i_private;
 
-        p->psi->erase(p->type, p->id, p->psi);
+        if (p->psi->erase)
+                p->psi->erase(p->type, p->id, p->psi);
 
         return simple_unlink(dir, dentry);
 }
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index f146d89179b..9ec22d3b429 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -207,8 +207,7 @@ void pstore_get_records(int quiet)
                 return;
 
         mutex_lock(&psi->read_mutex);
-        rc = psi->open(psi);
-        if (rc)
+        if (psi->open && psi->open(psi))
                 goto out;
 
         while ((size = psi->read(&id, &type, &time, &buf, psi)) > 0) {
@@ -219,7 +218,8 @@ void pstore_get_records(int quiet)
                 if (rc && (rc != -EEXIST || !quiet))
                         failed++;
         }
-        psi->close(psi);
+        if (psi->close)
+                psi->close(psi);
 out:
         mutex_unlock(&psi->read_mutex);