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| 2 | |
| 3 | * snapshot.c Ceph snapshot context utility routines (part of libceph)
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| 4 | *
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| 5 | * Copyright (C) 2013 Inktank Storage, Inc.
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| 6 |
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| 7 |
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| 8 | #include <linux/types.h>
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| 9 | #include <linux/export.h>
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| 10 | #include <linux/ceph/libceph.h>
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| 11 |
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| 12 | |
| 13 | * Ceph snapshot contexts are reference counted objects, and the
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| 14 | * returned structure holds a single reference. Acquire additional
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| 15 | * references with ceph_get_snap_context(), and release them with
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| 16 | * ceph_put_snap_context(). When the reference count reaches zero
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| 17 | * the entire structure is freed.
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| 18 |
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| 19 |
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| 20 | |
| 21 | * Create a new ceph snapshot context large enough to hold the
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| 22 | * indicated number of snapshot ids (which can be 0). Caller has
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| 23 | * to fill in snapc->seq and snapc->snaps[0..snap_count-1].
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| 24 | *
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| 25 | * Returns a null pointer if an error occurs.
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| 26 |
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| 27 | struct ceph_snap_context *ceph_create_snap_context(u32 snap_count,
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| 28 | gfp_t gfp_flags)
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| 29 | {
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| 30 | struct ceph_snap_context *snapc;
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| 31 | size_t size;
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| 32 |
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| 33 | size = sizeof (struct ceph_snap_context);
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| 34 | size += snap_count * sizeof (snapc->snaps[0]);
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| 35 | snapc = kzalloc(size, gfp_flags);
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| 36 | if (!snapc)
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| 37 | return NULL;
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| 38 |
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| 39 | refcount_set(&snapc->nref, 1);
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| 40 | snapc->num_snaps = snap_count;
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| 41 |
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| 42 | return snapc;
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| 43 | }
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| 44 | EXPORT_SYMBOL(ceph_create_snap_context);
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| 45 |
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| 46 | struct ceph_snap_context *ceph_get_snap_context(struct ceph_snap_context *sc)
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| 47 | {
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| 48 | if (sc)
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| 49 | refcount_inc(&sc->nref);
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| 50 | return sc;
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| 51 | }
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| 52 | EXPORT_SYMBOL(ceph_get_snap_context);
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| 53 |
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| 54 | void ceph_put_snap_context(struct ceph_snap_context *sc)
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| 55 | {
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| 56 | if (!sc)
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| 57 | return;
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| 58 | if (refcount_dec_and_test(&sc->nref)) {
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| 59 |
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| 60 | kfree(sc);
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| 61 | }
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| 62 | }
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| 63 | EXPORT_SYMBOL(ceph_put_snap_context);
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