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 */
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
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
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
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