3 files changed, 21 insertions, 11 deletions

diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index aeb19e68e086..11a2aa2a56c4 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -258,7 +258,7 @@ fail:
         return rc;
 }
 
-int pstore_fill_super(struct super_block *sb, void *data, int silent)
+static int pstore_fill_super(struct super_block *sb, void *data, int silent)
 {
         struct inode *inode;
 
diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index 9123cce28c1e..453030f9c5bc 100644
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -106,6 +106,8 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
         time->tv_sec = 0;
         time->tv_nsec = 0;
 
+        /* Update old/shadowed buffer. */
+        persistent_ram_save_old(prz);
         size = persistent_ram_old_size(prz);
         *buf = kmalloc(size, GFP_KERNEL);
         if (*buf == NULL)
@@ -184,6 +186,7 @@ static int ramoops_pstore_erase(enum pstore_type_id type, u64 id,
                 return -EINVAL;
 
         persistent_ram_free_old(cxt->przs[id]);
+        persistent_ram_zap(cxt->przs[id]);
 
         return 0;
 }
diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c
index 31f8d184f3a0..c5fbdbbf81ac 100644
--- a/fs/pstore/ram_core.c
+++ b/fs/pstore/ram_core.c
@@ -250,23 +250,24 @@ static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
         persistent_ram_update_ecc(prz, start, count);
 }
 
-static void __init
-persistent_ram_save_old(struct persistent_ram_zone *prz)
+void persistent_ram_save_old(struct persistent_ram_zone *prz)
 {
         struct persistent_ram_buffer *buffer = prz->buffer;
         size_t size = buffer_size(prz);
         size_t start = buffer_start(prz);
-        char *dest;
 
-        persistent_ram_ecc_old(prz);
+        if (!size)
+                return;
 
-        dest = kmalloc(size, GFP_KERNEL);
-        if (dest == NULL) {
+        if (!prz->old_log) {
+                persistent_ram_ecc_old(prz);
+                prz->old_log = kmalloc(size, GFP_KERNEL);
+        }
+        if (!prz->old_log) {
                 pr_err("persistent_ram: failed to allocate buffer\n");
                 return;
         }
 
-        prz->old_log = dest;
         prz->old_log_size = size;
         memcpy(prz->old_log, &buffer->data[start], size - start);
         memcpy(prz->old_log + size - start, &buffer->data[0], start);
@@ -319,6 +320,13 @@ void persistent_ram_free_old(struct persistent_ram_zone *prz)
         prz->old_log_size = 0;
 }
 
+void persistent_ram_zap(struct persistent_ram_zone *prz)
+{
+        atomic_set(&prz->buffer->start, 0);
+        atomic_set(&prz->buffer->size, 0);
+        persistent_ram_update_header_ecc(prz);
+}
+
 static void *persistent_ram_vmap(phys_addr_t start, size_t size)
 {
         struct page **pages;
@@ -405,6 +413,7 @@ static int __init persistent_ram_post_init(struct persistent_ram_zone *prz, bool
                                 " size %zu, start %zu\n",
                                buffer_size(prz), buffer_start(prz));
                         persistent_ram_save_old(prz);
+                        return 0;
                 }
         } else {
                 pr_info("persistent_ram: no valid data in buffer"
@@ -412,8 +421,7 @@ static int __init persistent_ram_post_init(struct persistent_ram_zone *prz, bool
         }
 
         prz->buffer->sig = PERSISTENT_RAM_SIG;
-        atomic_set(&prz->buffer->start, 0);
-        atomic_set(&prz->buffer->size, 0);
+        persistent_ram_zap(prz);
 
         return 0;
 }
@@ -448,7 +456,6 @@ struct persistent_ram_zone * __init persistent_ram_new(phys_addr_t start,
                 goto err;
 
         persistent_ram_post_init(prz, ecc);
-        persistent_ram_update_header_ecc(prz);
 
         return prz;
 err: