2 * snapshot.c Ceph snapshot context utility routines (part of libceph)
4 * Copyright (C) 2013 Inktank Storage, Inc.
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.
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.
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
23 #include <linux/types.h>
24 #include <linux/export.h>
25 #include <linux/ceph/libceph.h>
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.
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].
40 * Returns a null pointer if an error occurs.
42 struct ceph_snap_context
*ceph_create_snap_context(u32 snap_count
,
45 struct ceph_snap_context
*snapc
;
48 size
= sizeof (struct ceph_snap_context
);
49 size
+= snap_count
* sizeof (snapc
->snaps
[0]);
50 snapc
= kzalloc(size
, gfp_flags
);
54 atomic_set(&snapc
->nref
, 1);
55 snapc
->num_snaps
= snap_count
;
59 EXPORT_SYMBOL(ceph_create_snap_context
);
61 struct ceph_snap_context
*ceph_get_snap_context(struct ceph_snap_context
*sc
)
64 atomic_inc(&sc
->nref
);
67 EXPORT_SYMBOL(ceph_get_snap_context
);
69 void ceph_put_snap_context(struct ceph_snap_context
*sc
)
73 if (atomic_dec_and_test(&sc
->nref
)) {
74 /*printk(" deleting snap_context %p\n", sc);*/
78 EXPORT_SYMBOL(ceph_put_snap_context
);
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