pstore: Add extra context for writes and erases

EFI only provides small amounts of individual storage, and conventionally
puts metadata in the storage variable name. Rather than add a metadata
header to the (already limited) variable storage, it's easier for us to
modify pstore to pass all the information we need to construct a unique
variable name to the appropriate functions.

Signed-off-by: Matthew Garrett <[e-mail]>
Signed-off-by: Tony Luck <[e-mail]>

drivers/acpi/apei/erst.c

···
 static int erst_close_pstore(struct pstore_info *psi);
 static ssize_t erst_reader(u64 *id, enum pstore_type_id *type,
 			   struct timespec *time, struct pstore_info *psi);
-static u64 erst_writer(enum pstore_type_id type, size_t size,
+static u64 erst_writer(enum pstore_type_id type, int part, size_t size,
 		       struct pstore_info *psi);
-static int erst_clearer(u64 id, struct pstore_info *psi);
+static int erst_clearer(enum pstore_type_id type, u64 id,
+			struct pstore_info *psi);
 
 static struct pstore_info erst_info = {
 	.owner		= THIS_MODULE,
···
 	return (rc < 0) ? rc : (len - sizeof(*rcd));
 }
 
-static u64 erst_writer(enum pstore_type_id type, size_t size,
+static u64 erst_writer(enum pstore_type_id type, int part, size_t size,
 		       struct pstore_info *psi)
 {
 	struct cper_pstore_record *rcd = (struct cper_pstore_record *)
···
 	return rcd->hdr.record_id;
 }
 
-static int erst_clearer(u64 id, struct pstore_info *psi)
+static int erst_clearer(enum pstore_type_id type, u64 id,
+			struct pstore_info *psi)
 {
 	return erst_clear(id);
 }

fs/pstore/inode.c

···
 #define	PSTORE_NAMELEN	64
 
 struct pstore_private {
-	u64	id;
 	struct pstore_info *psi;
+	enum pstore_type_id type;
+	u64	id;
 	ssize_t	size;
 	char	data[];
 };
···
 {
 	struct pstore_private *p = dentry->d_inode->i_private;
 
-	p->psi->erase(p->id, p->psi);
+	p->psi->erase(p->type, p->id, p->psi);
 
 	return simple_unlink(dir, dentry);
 }
···
 	private = kmalloc(sizeof *private + size, GFP_KERNEL);
 	if (!private)
 		goto fail_alloc;
+	private->type = type;
 	private->id = id;
 	private->psi = psi;
 

fs/pstore/platform.c

···
 	oopscount++;
 	while (total < kmsg_bytes) {
 		dst = psinfo->buf;
-		hsize = sprintf(dst, "%s#%d Part%d\n", why, oopscount, part++);
+		hsize = sprintf(dst, "%s#%d Part%d\n", why, oopscount, part);
 		size = psinfo->bufsize - hsize;
 		dst += hsize;
 
···
 		memcpy(dst, s1 + s1_start, l1_cpy);
 		memcpy(dst + l1_cpy, s2 + s2_start, l2_cpy);
 
-		id = psinfo->write(PSTORE_TYPE_DMESG, hsize + l1_cpy + l2_cpy,
-				   psinfo);
+		id = psinfo->write(PSTORE_TYPE_DMESG, part,
+				   hsize + l1_cpy + l2_cpy, psinfo);
 		if (reason == KMSG_DUMP_OOPS && pstore_is_mounted())
 			pstore_mkfile(PSTORE_TYPE_DMESG, psinfo->name, id,
 				      psinfo->buf, hsize + l1_cpy + l2_cpy,
···
 		l1 -= l1_cpy;
 		l2 -= l2_cpy;
 		total += l1_cpy + l2_cpy;
+		part++;
 	}
 	mutex_unlock(&psinfo->buf_mutex);
 }
···
 
 	mutex_lock(&psinfo->buf_mutex);
 	memcpy(psinfo->buf, buf, size);
-	id = psinfo->write(type, size, psinfo);
+	id = psinfo->write(type, 0, size, psinfo);
 	if (pstore_is_mounted())
 		pstore_mkfile(PSTORE_TYPE_DMESG, psinfo->name, id, psinfo->buf,
 			      size, CURRENT_TIME, psinfo);

include/linux/pstore.h

···
 	int		(*close)(struct pstore_info *psi);
 	ssize_t		(*read)(u64 *id, enum pstore_type_id *type,
 			struct timespec *time, struct pstore_info *psi);
-	u64		(*write)(enum pstore_type_id type, size_t size,
+	u64		(*write)(enum pstore_type_id type, int part,
+			size_t size, struct pstore_info *psi);
+	int		(*erase)(enum pstore_type_id type, u64 id,
 			struct pstore_info *psi);
-	int		(*erase)(u64 id, struct pstore_info *psi);
 	void		*data;
 };