pstore: Add file extension to pstore file if compressed

In case decompression fails, add a ".enc.z" to indicate the file has
compressed data. This will help user space utilities to figure
out the file contents.

Signed-off-by: Aruna Balakrishnaiah <[e-mail]>
Reviewed-by: Kees Cook <[e-mail]>
Signed-off-by: Tony Luck <[e-mail]>

fs/pstore/inode.c

···
  * Set the mtime & ctime to the date that this record was originally stored.
  */
 int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id, int count,
-		  char *data, size_t size, struct timespec time,
-		  struct pstore_info *psi)
+		  char *data, bool compressed, size_t size,
+		  struct timespec time, struct pstore_info *psi)
 {
 	struct dentry		*root = pstore_sb->s_root;
 	struct dentry		*dentry;
···
 
 	switch (type) {
 	case PSTORE_TYPE_DMESG:
-		sprintf(name, "dmesg-%s-%lld", psname, id);
+		sprintf(name, "dmesg-%s-%lld%s", psname, id,
+						compressed ? ".enc.z" : "");
 		break;
 	case PSTORE_TYPE_CONSOLE:
 		sprintf(name, "console-%s", psname);

fs/pstore/internal.h

···
 extern void	pstore_set_kmsg_bytes(int);
 extern void	pstore_get_records(int);
 extern int	pstore_mkfile(enum pstore_type_id, char *psname, u64 id,
-			      int count, char *data, size_t size,
-			      struct timespec time, struct pstore_info *psi);
+			      int count, char *data, bool compressed,
+			      size_t size, struct timespec time,
+			      struct pstore_info *psi);
 extern int	pstore_is_mounted(void);
 
 #endif

fs/pstore/platform.c

···
 			if (unzipped_len > 0) {
 				buf = big_oops_buf;
 				size = unzipped_len;
+				compressed = false;
 			} else {
 				pr_err("pstore: decompression failed;"
 					"returned %d\n", unzipped_len);
+				compressed = true;
 			}
 		}
 		rc = pstore_mkfile(type, psi->name, id, count, buf,
-				  (size_t)size, time, psi);
+				  compressed, (size_t)size, time, psi);
 		if (unzipped_len < 0) {
 			/* Free buffer other than big oops */
 			kfree(buf);