[PATCH] Make efi-pstore return a unique id

[Madper Xie]

Pstore fs expects that backends provide a uniqued 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>
---
 drivers/firmware/efi/efi-pstore.c | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/firmware/efi/efi-pstore.c 
b/drivers/firmware/efi/efi-pstore.c
index 5002d50..0de9179 100644
--- a/drivers/firmware/efi/efi-pstore.c
+++ b/drivers/firmware/efi/efi-pstore.c
@@ -39,6 +39,17 @@ struct pstore_read_data {
        char **buf;
 };
 
+static u64 efi_generate_id(unsigned long timestamp, unsigned int part, int 
count)
+{
+       char id_str[64];
+       u64 id = 0;
+
+       sprintf(id_str, "%lu%u%d", timestamp, part, count);
+       if (kstrtoull(id_str, 10, &id))
+               pr_warn("efi-pstore: failed to generate id\n");
+       return id;
+}
+
 static int efi_pstore_read_func(struct efivar_entry *entry, void *data)
 {
        efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
@@ -57,17 +68,18 @@ static int efi_pstore_read_func(struct efivar_entry *entry, 
void *data)
 
        if (sscanf(name, "dump-type%u-%u-%d-%lu-%c",
                   cb_data->type, &part, &cnt, &time, &data_type) == 5) {
-               *cb_data->id = part;
+               *cb_data->id = efi_generate_id(time, part, cnt);
                *cb_data->count = cnt;
                cb_data->timespec->tv_sec = time;
                cb_data->timespec->tv_nsec = 0;
+
                if (data_type == 'C')
                        *cb_data->compressed = true;
                else
                        *cb_data->compressed = false;
        } else if (sscanf(name, "dump-type%u-%u-%d-%lu",
                   cb_data->type, &part, &cnt, &time) == 4) {
-               *cb_data->id = part;
+               *cb_data->id = efi_generate_id(time, part, cnt);
                *cb_data->count = cnt;
                cb_data->timespec->tv_sec = time;
                cb_data->timespec->tv_nsec = 0;
@@ -79,7 +91,7 @@ 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 = efi_generate_id(time, part, 0);
                *cb_data->count = 0;
                cb_data->timespec->tv_sec = time;
                cb_data->timespec->tv_nsec = 0;
@@ -125,9 +137,11 @@ static int efi_pstore_write(enum pstore_type_id type,
        efi_char16_t efi_name[DUMP_NAME_LEN];
        efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
        int i, ret = 0;
+       unsigned long timestamp;
 
+       timestamp = get_seconds();
        sprintf(name, "dump-type%u-%u-%d-%lu-%c", type, part, count,
-               get_seconds(), compressed ? 'C' : 'D');
+               timestamp, compressed ? 'C' : 'D');
 
        for (i = 0; i < DUMP_NAME_LEN; i++)
                efi_name[i] = name[i];
-- 
1.8.4.2

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