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); 64