// SPDX-License-Identifier: GPL-2.0-only

  /*
   * snapshot.c    Ceph snapshot context utility routines (part of libceph)
   *
   * Copyright (C) 2013 Inktank Storage, Inc.

   */

  #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;

  	refcount_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)

  		refcount_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 (refcount_dec_and_test(&sc->nref)) {

  		/*printk(" deleting snap_context %p
  ", sc);*/
  		kfree(sc);
  	}
  }
  EXPORT_SYMBOL(ceph_put_snap_context);