1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * snapshot.c    Ceph snapshot context utility routines (part of libceph)
4 *
5 * Copyright (C) 2013 Inktank Storage, Inc.
6 */
7
8#include <linux/types.h>
9#include <linux/export.h>
10#include <linux/ceph/libceph.h>
11
12/*
13 * Ceph snapshot contexts are reference counted objects, and the
14 * returned structure holds a single reference.  Acquire additional
15 * references with ceph_get_snap_context(), and release them with
16 * ceph_put_snap_context().  When the reference count reaches zero
17 * the entire structure is freed.
18 */
19
20/*
21 * Create a new ceph snapshot context large enough to hold the
22 * indicated number of snapshot ids (which can be 0).  Caller has
23 * to fill in snapc->seq and snapc->snaps[0..snap_count-1].
24 *
25 * Returns a null pointer if an error occurs.
26 */
27struct ceph_snap_context *ceph_create_snap_context(u32 snap_count,
28						gfp_t gfp_flags)
29{
30	struct ceph_snap_context *snapc;
31	size_t size;
32
33	size = sizeof (struct ceph_snap_context);
34	size += snap_count * sizeof (snapc->snaps[0]);
35	snapc = kzalloc(size, gfp_flags);
36	if (!snapc)
37		return NULL;
38
39	refcount_set(&snapc->nref, 1);
40	snapc->num_snaps = snap_count;
41
42	return snapc;
43}
44EXPORT_SYMBOL(ceph_create_snap_context);
45
46struct ceph_snap_context *ceph_get_snap_context(struct ceph_snap_context *sc)
47{
48	if (sc)
49		refcount_inc(&sc->nref);
50	return sc;
51}
52EXPORT_SYMBOL(ceph_get_snap_context);
53
54void ceph_put_snap_context(struct ceph_snap_context *sc)
55{
56	if (!sc)
57		return;
58	if (refcount_dec_and_test(&sc->nref)) {
59		/*printk(" deleting snap_context %p\n", sc);*/
60		kfree(sc);
61	}
62}
63EXPORT_SYMBOL(ceph_put_snap_context);
64