snapshot.c
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/*
* snapshot.c Ceph snapshot context utility routines (part of libceph)
*
* Copyright (C) 2013 Inktank Storage, Inc.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* version 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
#include <stddef.h>
#include <linux/types.h>
#include <linux/export.h>
#include <linux/ceph/libceph.h>
/*
* Ceph snapshot contexts are reference counted objects, and the
* returned structure holds a single reference. Acquire additional
* references with ceph_get_snap_context(), and release them with
* ceph_put_snap_context(). When the reference count reaches zero
* the entire structure is freed.
*/
/*
* Create a new ceph snapshot context large enough to hold the
* indicated number of snapshot ids (which can be 0). Caller has
* to fill in snapc->seq and snapc->snaps[0..snap_count-1].
*
* Returns a null pointer if an error occurs.
*/
struct ceph_snap_context *ceph_create_snap_context(u32 snap_count,
gfp_t gfp_flags)
{
struct ceph_snap_context *snapc;
size_t size;
size = sizeof (struct ceph_snap_context);
size += snap_count * sizeof (snapc->snaps[0]);
snapc = kzalloc(size, gfp_flags);
if (!snapc)
return NULL;
atomic_set(&snapc->nref, 1);
snapc->num_snaps = snap_count;
return snapc;
}
EXPORT_SYMBOL(ceph_create_snap_context);
struct ceph_snap_context *ceph_get_snap_context(struct ceph_snap_context *sc)
{
if (sc)
atomic_inc(&sc->nref);
return sc;
}
EXPORT_SYMBOL(ceph_get_snap_context);
void ceph_put_snap_context(struct ceph_snap_context *sc)
{
if (!sc)
return;
if (atomic_dec_and_test(&sc->nref)) {
/*printk(" deleting snap_context %p\n", sc);*/
kfree(sc);
}
}
EXPORT_SYMBOL(ceph_put_snap_context);