06dfa96399
refcount_t type and corresponding API should be used instead of atomic_t when the variable is used as a reference counter. This allows to avoid accidental refcounter overflows that might lead to use-after-free situations. Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: David Windsor <dwindsor@gmail.com> Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
76 lines
2.2 KiB
C
76 lines
2.2 KiB
C
/*
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* snapshot.c Ceph snapshot context utility routines (part of libceph)
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*
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* Copyright (C) 2013 Inktank Storage, Inc.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* version 2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA.
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*/
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#include <linux/types.h>
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#include <linux/export.h>
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#include <linux/ceph/libceph.h>
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/*
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* Ceph snapshot contexts are reference counted objects, and the
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* returned structure holds a single reference. Acquire additional
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* references with ceph_get_snap_context(), and release them with
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* ceph_put_snap_context(). When the reference count reaches zero
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* the entire structure is freed.
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*/
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/*
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* Create a new ceph snapshot context large enough to hold the
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* indicated number of snapshot ids (which can be 0). Caller has
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* to fill in snapc->seq and snapc->snaps[0..snap_count-1].
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*
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* Returns a null pointer if an error occurs.
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*/
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struct ceph_snap_context *ceph_create_snap_context(u32 snap_count,
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gfp_t gfp_flags)
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{
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struct ceph_snap_context *snapc;
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size_t size;
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size = sizeof (struct ceph_snap_context);
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size += snap_count * sizeof (snapc->snaps[0]);
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snapc = kzalloc(size, gfp_flags);
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if (!snapc)
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return NULL;
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refcount_set(&snapc->nref, 1);
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snapc->num_snaps = snap_count;
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return snapc;
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}
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EXPORT_SYMBOL(ceph_create_snap_context);
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struct ceph_snap_context *ceph_get_snap_context(struct ceph_snap_context *sc)
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{
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if (sc)
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refcount_inc(&sc->nref);
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return sc;
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}
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EXPORT_SYMBOL(ceph_get_snap_context);
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void ceph_put_snap_context(struct ceph_snap_context *sc)
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{
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if (!sc)
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return;
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if (refcount_dec_and_test(&sc->nref)) {
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/*printk(" deleting snap_context %p\n", sc);*/
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kfree(sc);
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}
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}
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EXPORT_SYMBOL(ceph_put_snap_context);
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