| 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, flags: gfp_flags); |
| 36 | if (!snapc) |
| 37 | return NULL; |
| 38 | |
| 39 | refcount_set(r: &snapc->nref, n: 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(r: &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(r: &sc->nref)) { |
| 59 | /*printk(" deleting snap_context %p\n", sc);*/ |
| 60 | kfree(objp: sc); |
| 61 | } |
| 62 | } |
| 63 | EXPORT_SYMBOL(ceph_put_snap_context); |
| 64 |