| xj | b04a402 | 2021-11-25 15:01:52 +0800 | [diff] [blame] | 1 | /* |
| 2 | * snapshot.c Ceph snapshot context utility routines (part of libceph) |
| 3 | * |
| 4 | * Copyright (C) 2013 Inktank Storage, Inc. |
| 5 | * |
| 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. |
| 9 | * |
| 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. |
| 14 | * |
| 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 |
| 18 | * 02110-1301, USA. |
| 19 | */ |
| 20 | |
| 21 | #include <linux/types.h> |
| 22 | #include <linux/export.h> |
| 23 | #include <linux/ceph/libceph.h> |
| 24 | |
| 25 | /* |
| 26 | * Ceph snapshot contexts are reference counted objects, and the |
| 27 | * returned structure holds a single reference. Acquire additional |
| 28 | * references with ceph_get_snap_context(), and release them with |
| 29 | * ceph_put_snap_context(). When the reference count reaches zero |
| 30 | * the entire structure is freed. |
| 31 | */ |
| 32 | |
| 33 | /* |
| 34 | * Create a new ceph snapshot context large enough to hold the |
| 35 | * indicated number of snapshot ids (which can be 0). Caller has |
| 36 | * to fill in snapc->seq and snapc->snaps[0..snap_count-1]. |
| 37 | * |
| 38 | * Returns a null pointer if an error occurs. |
| 39 | */ |
| 40 | struct ceph_snap_context *ceph_create_snap_context(u32 snap_count, |
| 41 | gfp_t gfp_flags) |
| 42 | { |
| 43 | struct ceph_snap_context *snapc; |
| 44 | size_t size; |
| 45 | |
| 46 | size = sizeof (struct ceph_snap_context); |
| 47 | size += snap_count * sizeof (snapc->snaps[0]); |
| 48 | snapc = kzalloc(size, gfp_flags); |
| 49 | if (!snapc) |
| 50 | return NULL; |
| 51 | |
| 52 | refcount_set(&snapc->nref, 1); |
| 53 | snapc->num_snaps = snap_count; |
| 54 | |
| 55 | return snapc; |
| 56 | } |
| 57 | EXPORT_SYMBOL(ceph_create_snap_context); |
| 58 | |
| 59 | struct ceph_snap_context *ceph_get_snap_context(struct ceph_snap_context *sc) |
| 60 | { |
| 61 | if (sc) |
| 62 | refcount_inc(&sc->nref); |
| 63 | return sc; |
| 64 | } |
| 65 | EXPORT_SYMBOL(ceph_get_snap_context); |
| 66 | |
| 67 | void ceph_put_snap_context(struct ceph_snap_context *sc) |
| 68 | { |
| 69 | if (!sc) |
| 70 | return; |
| 71 | if (refcount_dec_and_test(&sc->nref)) { |
| 72 | /*printk(" deleting snap_context %p\n", sc);*/ |
| 73 | kfree(sc); |
| 74 | } |
| 75 | } |
| 76 | EXPORT_SYMBOL(ceph_put_snap_context); |