On Tue, Jul 31, 2018 at 11:10 PM Chengguang Xu <cgxu519@xxxxxxx> wrote:
>
> Use refcount_t to replace atomic_t when operating refcount.
> Meanwhile, introduce a variable to avoid calling refcount_read
> twice in debug message.
>
> Signed-off-by: Chengguang Xu <cgxu519@xxxxxxx>
> ---
> fs/ceph/snap.c | 18 ++++++++++--------
> fs/ceph/super.h | 2 +-
> 2 files changed, 11 insertions(+), 9 deletions(-)
>
> diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
> index 01b0144c0b73..b5cff23d9ea2 100644
> --- a/fs/ceph/snap.c
> +++ b/fs/ceph/snap.c
> @@ -63,15 +63,15 @@
> void ceph_get_snap_realm(struct ceph_mds_client *mdsc,
> struct ceph_snap_realm *realm)
> {
> - dout("get_realm %p %d -> %d\n", realm,
> - atomic_read(&realm->nref), atomic_read(&realm->nref)+1);
> /*
> * since we _only_ increment realm refs or empty the empty
> * list with snap_rwsem held, adjusting the empty list here is
> * safe. we do need to protect against concurrent empty list
> * additions, however.
> */
> - if (atomic_inc_return(&realm->nref) == 1) {
> + if (refcount_inc_not_zero(&realm->nref)) {
refcount_inc_not_zero and atomic_inc_return are completely different
> + unsigned int refcnt = refcount_read(&realm->nref);
> + dout("get_realm %p %d -> %d\n", realm, refcnt - 1, refcnt);
> spin_lock(&mdsc->snap_empty_lock);
> list_del_init(&realm->empty_item);
> spin_unlock(&mdsc->snap_empty_lock);
> @@ -115,7 +115,7 @@ static struct ceph_snap_realm *ceph_create_snap_realm(
> if (!realm)
> return ERR_PTR(-ENOMEM);
>
> - atomic_set(&realm->nref, 1); /* for caller */
> + refcount_set(&realm->nref, 1); /* for caller */
> realm->ino = ino;
> INIT_LIST_HEAD(&realm->children);
> INIT_LIST_HEAD(&realm->child_item);
> @@ -193,9 +193,10 @@ static void __destroy_snap_realm(struct ceph_mds_client *mdsc,
> static void __put_snap_realm(struct ceph_mds_client *mdsc,
> struct ceph_snap_realm *realm)
> {
> + unsigned int refcnt = refcount_read(&realm->nref);
> dout("__put_snap_realm %llx %p %d -> %d\n", realm->ino, realm,
> - atomic_read(&realm->nref), atomic_read(&realm->nref)-1);
> - if (atomic_dec_and_test(&realm->nref))
> + refcnt, refcnt - 1);
> + if (refcount_dec_and_test(&realm->nref))
> __destroy_snap_realm(mdsc, realm);
> }
>
> @@ -205,9 +206,10 @@ static void __put_snap_realm(struct ceph_mds_client *mdsc,
> void ceph_put_snap_realm(struct ceph_mds_client *mdsc,
> struct ceph_snap_realm *realm)
> {
> + unsigned int refcnt = refcount_read(&realm->nref);
> dout("put_snap_realm %llx %p %d -> %d\n", realm->ino, realm,
> - atomic_read(&realm->nref), atomic_read(&realm->nref)-1);
> - if (!atomic_dec_and_test(&realm->nref))
> + refcnt, refcnt - 1);
> + if (!refcount_dec_and_test(&realm->nref))
> return;
>
> if (down_write_trylock(&mdsc->snap_rwsem)) {
> diff --git a/fs/ceph/super.h b/fs/ceph/super.h
> index fe11d6903b29..d4b0ca5d7a15 100644
> --- a/fs/ceph/super.h
> +++ b/fs/ceph/super.h
> @@ -761,7 +761,7 @@ struct ceph_readdir_cache_control {
> struct ceph_snap_realm {
> u64 ino;
> struct inode *inode;
> - atomic_t nref;
> + refcount_t nref;
> struct rb_node node;
>
> u64 created, seq;
> --
> 2.17.1
>
> --
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