efi-pstore: Make efi-pstore return a unique id

commit fdeadb43fdf1e7d5698c027b555c389174548e5a upstream.

Pstore fs expects that backends provide a unique id which could avoid
pstore making entries as duplication or denominating entries the same
name. So I combine the timestamp, part and count into id.

Signed-off-by: Madper Xie <cxie@redhat.com>
Cc: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: stable@vger.kernel.org
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
[hkp: Backported to 3.10: adjust context]
Signed-off-by: Hu Keping <hukeping@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/firmware/efi/efi-pstore.c b/drivers/firmware/efi/efi-pstore.c
index 202d2c85ba2e79e2db866e78a03dffa240967f25..9b2622e0a07e8800eb955b11fc4174110d6a2405 100644 (file)
--- a/drivers/firmware/efi/efi-pstore.c
+++ b/drivers/firmware/efi/efi-pstore.c
@@ -38,6 +38,12 @@ struct pstore_read_data {
        char **buf;
 };
 
+static inline u64 generic_id(unsigned long timestamp,
+                            unsigned int part, int count)
+{
+       return (timestamp * 100 + part) * 1000 + count;
+}
+
 static int efi_pstore_read_func(struct efivar_entry *entry, void *data)
 {
        efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
@@ -56,7 +62,7 @@ static int efi_pstore_read_func(struct efivar_entry *entry, void *data)
 
        if (sscanf(name, "dump-type%u-%u-%d-%lu",
                   cb_data->type, &part, &cnt, &time) == 4) {
-               *cb_data->id = part;
+               *cb_data->id = generic_id(time, part, cnt);
                *cb_data->count = cnt;
                cb_data->timespec->tv_sec = time;
                cb_data->timespec->tv_nsec = 0;
@@ -67,7 +73,7 @@ static int efi_pstore_read_func(struct efivar_entry *entry, void *data)
                 * which doesn't support holding
                 * multiple logs, remains.
                 */
-               *cb_data->id = part;
+               *cb_data->id = generic_id(time, part, 0);
                *cb_data->count = 0;
                cb_data->timespec->tv_sec = time;
                cb_data->timespec->tv_nsec = 0;
@@ -185,14 +191,16 @@ static int efi_pstore_erase(enum pstore_type_id type, u64 id, int count,
        char name[DUMP_NAME_LEN];
        efi_char16_t efi_name[DUMP_NAME_LEN];
        int found, i;
+       unsigned int part;
 
-       sprintf(name, "dump-type%u-%u-%d-%lu", type, (unsigned int)id, count,
-               time.tv_sec);
+       do_div(id, 1000);
+       part = do_div(id, 100);
+       sprintf(name, "dump-type%u-%u-%d-%lu", type, part, count, time.tv_sec);
 
        for (i = 0; i < DUMP_NAME_LEN; i++)
                efi_name[i] = name[i];
 
-       edata.id = id;
+       edata.id = part;
        edata.type = type;
        edata.count = count;
        edata.time = time;