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1 | /* |
2 | * snapshot.c Ceph snapshot context utility routines (part of libceph) |
3 | * |
4 | * Copyright (C) 2013 Inktank Storage, Inc. |
5 | * |
6 | * This program is free software; you can redistribute it and/or |
7 | * modify it under the terms of the GNU General Public License |
8 | * version 2 as published by the Free Software Foundation. |
9 | * |
10 | * This program is distributed in the hope that it will be useful, |
11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
13 | * General Public License for more details. |
14 | * |
15 | * You should have received a copy of the GNU General Public License |
16 | * along with this program; if not, write to the Free Software |
17 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
18 | * 02110-1301, USA. |
19 | */ |
20 | |
21 | #include <stddef.h> |
22 | |
23 | #include <linux/types.h> |
24 | #include <linux/export.h> |
25 | #include <linux/ceph/libceph.h> |
26 | |
27 | /* |
28 | * Ceph snapshot contexts are reference counted objects, and the |
29 | * returned structure holds a single reference. Acquire additional |
30 | * references with ceph_get_snap_context(), and release them with |
31 | * ceph_put_snap_context(). When the reference count reaches zero |
32 | * the entire structure is freed. |
33 | */ |
34 | |
35 | /* |
36 | * Create a new ceph snapshot context large enough to hold the |
37 | * indicated number of snapshot ids (which can be 0). Caller has |
38 | * to fill in snapc->seq and snapc->snaps[0..snap_count-1]. |
39 | * |
40 | * Returns a null pointer if an error occurs. |
41 | */ |
42 | struct ceph_snap_context *ceph_create_snap_context(u32 snap_count, |
43 | gfp_t gfp_flags) |
44 | { |
45 | struct ceph_snap_context *snapc; |
46 | size_t size; |
47 | |
48 | size = sizeof (struct ceph_snap_context); |
49 | size += snap_count * sizeof (snapc->snaps[0]); |
50 | snapc = kzalloc(size, gfp_flags); |
51 | if (!snapc) |
52 | return NULL; |
53 | |
54 | atomic_set(&snapc->nref, 1); |
55 | snapc->num_snaps = snap_count; |
56 | |
57 | return snapc; |
58 | } |
59 | EXPORT_SYMBOL(ceph_create_snap_context); |
60 | |
61 | struct ceph_snap_context *ceph_get_snap_context(struct ceph_snap_context *sc) |
62 | { |
63 | if (sc) |
64 | atomic_inc(&sc->nref); |
65 | return sc; |
66 | } |
67 | EXPORT_SYMBOL(ceph_get_snap_context); |
68 | |
69 | void ceph_put_snap_context(struct ceph_snap_context *sc) |
70 | { |
71 | if (!sc) |
72 | return; |
73 | if (atomic_dec_and_test(&sc->nref)) { |
74 | /*printk(" deleting snap_context %p\n", sc);*/ |
75 | kfree(sc); |
76 | } |
77 | } |
78 | EXPORT_SYMBOL(ceph_put_snap_context); |
79 |
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