net/ceph/snapshot.c

   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);