libceph: support for advisory locking on RADOS objects

This patch adds support for rados lock, unlock and break lock.

Based heavily on code by Mike Christie <michaelc@cs.wisc.edu>.
Signed-off-by: Douglas Fuller <dfuller@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Mike Christie <mchristi@redhat.com>
Reviewed-by: Alex Elder <elder@linaro.org>

include/linux/ceph/cls_lock_client.h

+#ifndef _LINUX_CEPH_CLS_LOCK_CLIENT_H
+#define _LINUX_CEPH_CLS_LOCK_CLIENT_H
+
+#include <linux/ceph/osd_client.h>
+
+enum ceph_cls_lock_type {
+	CEPH_CLS_LOCK_NONE = 0,
+	CEPH_CLS_LOCK_EXCLUSIVE = 1,
+	CEPH_CLS_LOCK_SHARED = 2,
+};
+
+int ceph_cls_lock(struct ceph_osd_client *osdc,
+		  struct ceph_object_id *oid,
+		  struct ceph_object_locator *oloc,
+		  char *lock_name, u8 type, char *cookie,
+		  char *tag, char *desc, u8 flags);
+int ceph_cls_unlock(struct ceph_osd_client *osdc,
+		    struct ceph_object_id *oid,
+		    struct ceph_object_locator *oloc,
+		    char *lock_name, char *cookie);
+int ceph_cls_break_lock(struct ceph_osd_client *osdc,
+			struct ceph_object_id *oid,
+			struct ceph_object_locator *oloc,
+			char *lock_name, char *cookie,
+			struct ceph_entity_name *locker);
+
+#endif

net/ceph/Makefile

@@ -5,6 +5,7 @@ obj-$(CONFIG_CEPH_LIB) += libceph.o
 
 libceph-y := ceph_common.o messenger.o msgpool.o buffer.o pagelist.o \
 	mon_client.o \
+	cls_lock_client.o \
 	osd_client.o osdmap.o crush/crush.o crush/mapper.o crush/hash.o \
 	debugfs.o \
 	auth.o auth_none.o \

net/ceph/cls_lock_client.c

+#include <linux/ceph/ceph_debug.h>
+
+#include <linux/types.h>
+#include <linux/slab.h>
+
+#include <linux/ceph/cls_lock_client.h>
+#include <linux/ceph/decode.h>
+
+/**
+ * ceph_cls_lock - grab rados lock for object
+ * @oid, @oloc: object to lock
+ * @lock_name: the name of the lock
+ * @type: lock type (CEPH_CLS_LOCK_EXCLUSIVE or CEPH_CLS_LOCK_SHARED)
+ * @cookie: user-defined identifier for this instance of the lock
+ * @tag: user-defined tag
+ * @desc: user-defined lock description
+ * @flags: lock flags
+ *
+ * All operations on the same lock should use the same tag.
+ */
+int ceph_cls_lock(struct ceph_osd_client *osdc,
+		  struct ceph_object_id *oid,
+		  struct ceph_object_locator *oloc,
+		  char *lock_name, u8 type, char *cookie,
+		  char *tag, char *desc, u8 flags)
+{
+	int lock_op_buf_size;
+	int name_len = strlen(lock_name);
+	int cookie_len = strlen(cookie);
+	int tag_len = strlen(tag);
+	int desc_len = strlen(desc);
+	void *p, *end;
+	struct page *lock_op_page;
+	struct timespec mtime;
+	int ret;
+
+	lock_op_buf_size = name_len + sizeof(__le32) +
+			   cookie_len + sizeof(__le32) +
+			   tag_len + sizeof(__le32) +
+			   desc_len + sizeof(__le32) +
+			   sizeof(struct ceph_timespec) +
+			   /* flag and type */
+			   sizeof(u8) + sizeof(u8) +
+			   CEPH_ENCODING_START_BLK_LEN;
+	if (lock_op_buf_size > PAGE_SIZE)
+		return -E2BIG;
+
+	lock_op_page = alloc_page(GFP_NOIO);
+	if (!lock_op_page)
+		return -ENOMEM;
+
+	p = page_address(lock_op_page);
+	end = p + lock_op_buf_size;
+
+	/* encode cls_lock_lock_op struct */
+	ceph_start_encoding(&p, 1, 1,
+			    lock_op_buf_size - CEPH_ENCODING_START_BLK_LEN);
+	ceph_encode_string(&p, end, lock_name, name_len);
+	ceph_encode_8(&p, type);
+	ceph_encode_string(&p, end, cookie, cookie_len);
+	ceph_encode_string(&p, end, tag, tag_len);
+	ceph_encode_string(&p, end, desc, desc_len);
+	/* only support infinite duration */
+	memset(&mtime, 0, sizeof(mtime));
+	ceph_encode_timespec(p, &mtime);
+	p += sizeof(struct ceph_timespec);
+	ceph_encode_8(&p, flags);
+
+	dout("%s lock_name %s type %d cookie %s tag %s desc %s flags 0x%x\n",
+	     __func__, lock_name, type, cookie, tag, desc, flags);
+	ret = ceph_osdc_call(osdc, oid, oloc, "lock", "lock",
+			     CEPH_OSD_FLAG_WRITE | CEPH_OSD_FLAG_ONDISK,
+			     lock_op_page, lock_op_buf_size, NULL, NULL);
+
+	dout("%s: status %d\n", __func__, ret);
+	__free_page(lock_op_page);
+	return ret;
+}
+EXPORT_SYMBOL(ceph_cls_lock);
+
+/**
+ * ceph_cls_unlock - release rados lock for object
+ * @oid, @oloc: object to lock
+ * @lock_name: the name of the lock
+ * @cookie: user-defined identifier for this instance of the lock
+ */
+int ceph_cls_unlock(struct ceph_osd_client *osdc,
+		    struct ceph_object_id *oid,
+		    struct ceph_object_locator *oloc,
+		    char *lock_name, char *cookie)
+{
+	int unlock_op_buf_size;
+	int name_len = strlen(lock_name);
+	int cookie_len = strlen(cookie);
+	void *p, *end;
+	struct page *unlock_op_page;
+	int ret;
+
+	unlock_op_buf_size = name_len + sizeof(__le32) +
+			     cookie_len + sizeof(__le32) +
+			     CEPH_ENCODING_START_BLK_LEN;
+	if (unlock_op_buf_size > PAGE_SIZE)
+		return -E2BIG;
+
+	unlock_op_page = alloc_page(GFP_NOIO);
+	if (!unlock_op_page)
+		return -ENOMEM;
+
+	p = page_address(unlock_op_page);
+	end = p + unlock_op_buf_size;
+
+	/* encode cls_lock_unlock_op struct */
+	ceph_start_encoding(&p, 1, 1,
+			    unlock_op_buf_size - CEPH_ENCODING_START_BLK_LEN);
+	ceph_encode_string(&p, end, lock_name, name_len);
+	ceph_encode_string(&p, end, cookie, cookie_len);
+
+	dout("%s lock_name %s cookie %s\n", __func__, lock_name, cookie);
+	ret = ceph_osdc_call(osdc, oid, oloc, "lock", "unlock",
+			     CEPH_OSD_FLAG_WRITE | CEPH_OSD_FLAG_ONDISK,
+			     unlock_op_page, unlock_op_buf_size, NULL, NULL);
+
+	dout("%s: status %d\n", __func__, ret);
+	__free_page(unlock_op_page);
+	return ret;
+}
+EXPORT_SYMBOL(ceph_cls_unlock);
+
+/**
+ * ceph_cls_break_lock - release rados lock for object for specified client
+ * @oid, @oloc: object to lock
+ * @lock_name: the name of the lock
+ * @cookie: user-defined identifier for this instance of the lock
+ * @locker: current lock owner
+ */
+int ceph_cls_break_lock(struct ceph_osd_client *osdc,
+			struct ceph_object_id *oid,
+			struct ceph_object_locator *oloc,
+			char *lock_name, char *cookie,
+			struct ceph_entity_name *locker)
+{
+	int break_op_buf_size;
+	int name_len = strlen(lock_name);
+	int cookie_len = strlen(cookie);
+	struct page *break_op_page;
+	void *p, *end;
+	int ret;
+
+	break_op_buf_size = name_len + sizeof(__le32) +
+			    cookie_len + sizeof(__le32) +
+			    sizeof(u8) + sizeof(__le64) +
+			    CEPH_ENCODING_START_BLK_LEN;
+	if (break_op_buf_size > PAGE_SIZE)
+		return -E2BIG;
+
+	break_op_page = alloc_page(GFP_NOIO);
+	if (!break_op_page)
+		return -ENOMEM;
+
+	p = page_address(break_op_page);
+	end = p + break_op_buf_size;
+
+	/* encode cls_lock_break_op struct */
+	ceph_start_encoding(&p, 1, 1,
+			    break_op_buf_size - CEPH_ENCODING_START_BLK_LEN);
+	ceph_encode_string(&p, end, lock_name, name_len);
+	ceph_encode_copy(&p, locker, sizeof(*locker));
+	ceph_encode_string(&p, end, cookie, cookie_len);
+
+	dout("%s lock_name %s cookie %s locker %s%llu\n", __func__, lock_name,
+	     cookie, ENTITY_NAME(*locker));
+	ret = ceph_osdc_call(osdc, oid, oloc, "lock", "break_lock",
+			     CEPH_OSD_FLAG_WRITE | CEPH_OSD_FLAG_ONDISK,
+			     break_op_page, break_op_buf_size, NULL, NULL);
+
+	dout("%s: status %d\n", __func__, ret);
+	__free_page(break_op_page);
+	return ret;
+}
+EXPORT_SYMBOL(ceph_cls_break_lock);