3.8.13.15 -stable review patch.  If anyone has any objections, please let me 
know.

------------------

From: Madper Xie <c...@redhat.com>

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 <c...@redhat.com>
Cc: Seiji Aguchi <seiji.agu...@hds.com>
Signed-off-by: Matt Fleming <matt.flem...@intel.com>
[ kamal: backport to 3.8 ]
Signed-off-by: Kamal Mostafa <ka...@canonical.com>
---
 drivers/firmware/efivars.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index e3e95dd..e2d4c7a 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -1314,6 +1314,12 @@ static int efi_pstore_close(struct pstore_info *psi)
        return 0;
 }
 
+static inline u64 generic_id(unsigned long timestamp,
+                            unsigned int part, int count)
+{
+       return (timestamp * 100 + part) * 1000 + count;
+}
+
 static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type,
                               int *count, struct timespec *timespec,
                               char **buf, struct pstore_info *psi)
@@ -1334,7 +1340,7 @@ static ssize_t efi_pstore_read(u64 *id, enum 
pstore_type_id *type,
                        }
                        if (sscanf(name, "dump-type%u-%u-%d-%lu",
                                   type, &part, &cnt, &time) == 4) {
-                               *id = part;
+                               *id = generic_id(time, part, cnt);
                                *count = cnt;
                                timespec->tv_sec = time;
                                timespec->tv_nsec = 0;
@@ -1345,7 +1351,7 @@ static ssize_t efi_pstore_read(u64 *id, enum 
pstore_type_id *type,
                                 * which doesn't support holding
                                 * multiple logs, remains.
                                 */
-                               *id = part;
+                               *id = generic_id(time, part, cnt);
                                *count = 0;
                                timespec->tv_sec = time;
                                timespec->tv_nsec = 0;
@@ -1436,9 +1442,11 @@ static int efi_pstore_erase(enum pstore_type_id type, 
u64 id, int count,
        struct efivars *efivars = psi->data;
        struct efivar_entry *entry, *found = NULL;
        int 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);
 
        spin_lock_irq(&efivars->lock);
 
-- 
1.8.3.2

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