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  */
ceph_create_snap_context(u32 snap_count,gfp_t gfp_flags)27 struct 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 }
44 EXPORT_SYMBOL(ceph_create_snap_context);
45 
ceph_get_snap_context(struct ceph_snap_context * sc)46 struct 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 }
52 EXPORT_SYMBOL(ceph_get_snap_context);
53 
ceph_put_snap_context(struct ceph_snap_context * sc)54 void 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 }
63 EXPORT_SYMBOL(ceph_put_snap_context);
64