From mboxrd@z Thu Jan  1 00:00:00 1970
From: Fred Isaman <iisaman@citi.umich.edu>
Subject: Re: [PATCH 2/8] pnfs-submit: clean locking infrastructure
Date: Fri, 28 May 2010 13:27:17 -0400
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Cc: bhalevy@panasas.com, linux-nfs@vger.kernel.org
To: Alexandros Batsakis <batsakis@netapp.com>
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On Mon, May 17, 2010 at 1:56 PM, Alexandros Batsakis
<batsakis@netapp.com> wrote:
> (also minor cleanup of pnfs_free_layout())
>
> Signed-off-by: Alexandros Batsakis <batsakis@netapp.com>
>
> Conflicts:
>
> =A0 =A0 =A0 =A0fs/nfs/pnfs.c
> ---
> =A0fs/nfs/pnfs.c | =A0 80 +++++++++++++++++++++++++++++++++++++------=
-------------
> =A01 files changed, 53 insertions(+), 27 deletions(-)
>
> diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
> index b72c013..74cb998 100644
> --- a/fs/nfs/pnfs.c
> +++ b/fs/nfs/pnfs.c
> @@ -1,4 +1,4 @@
> -/*
> + /*
> =A0* =A0linux/fs/nfs/pnfs.c
> =A0*
> =A0* =A0pNFS functions to call and manage layout drivers.
> @@ -60,6 +60,8 @@ static int pnfs_initialized;
> =A0static void pnfs_free_layout(struct pnfs_layout_type *lo,
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 struct nfs4_p=
nfs_layout_segment *range);
> =A0static enum pnfs_try_status pnfs_commit(struct nfs_write_data *dat=
a, int sync);
> +static inline void lock_current_layout(struct nfs_inode *nfsi);
> +static inline void unlock_current_layout(struct nfs_inode *nfsi);
>
> =A0/* Locking:
> =A0*
> @@ -153,16 +155,17 @@ pnfs_need_layoutcommit(struct nfs_inode *nfsi, =
struct nfs_open_context *ctx)
> =A0{
> =A0 =A0 =A0 =A0dprintk("%s: has_layout=3D%d layoutcommit_ctx=3D%p ctx=
=3D%p\n", __func__,
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0has_layout(nfsi), nfsi->layout.layoutc=
ommit_ctx, ctx);
> - =A0 =A0 =A0 spin_lock(&nfsi->lo_lock);
> +
> + =A0 =A0 =A0 lock_current_layout(nfsi);
> =A0 =A0 =A0 =A0if (has_layout(nfsi) && !nfsi->layout.layoutcommit_ctx=
) {
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0nfsi->layout.layoutcommit_ctx =3D get_=
nfs_open_context(ctx);
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0nfsi->change_attr++;
> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 spin_unlock(&nfsi->lo_lock);
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 unlock_current_layout(nfsi);
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0dprintk("%s: Set layoutcommit_ctx=3D%p=
\n", __func__,
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0nfsi->layout.layoutcom=
mit_ctx);
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0return;
> =A0 =A0 =A0 =A0}
> - =A0 =A0 =A0 spin_unlock(&nfsi->lo_lock);
> + =A0 =A0 =A0 unlock_current_layout(nfsi);
> =A0}
>
> =A0/* Update last_write_offset for layoutcommit.
> @@ -175,7 +178,7 @@ pnfs_update_last_write(struct nfs_inode *nfsi, lo=
ff_t offset, size_t extent)
> =A0{
> =A0 =A0 =A0 =A0loff_t end_pos;
>
> - =A0 =A0 =A0 spin_lock(&nfsi->lo_lock);
> + =A0 =A0 =A0 lock_current_layout(nfsi);
> =A0 =A0 =A0 =A0if (offset < nfsi->layout.pnfs_write_begin_pos)
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0nfsi->layout.pnfs_write_begin_pos =3D =
offset;
> =A0 =A0 =A0 =A0end_pos =3D offset + extent - 1; /* I'm being inclusiv=
e */
> @@ -187,7 +190,7 @@ pnfs_update_last_write(struct nfs_inode *nfsi, lo=
ff_t offset, size_t extent)
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0(unsigned long) offset ,
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0(unsigned long) nfsi->layout.pnfs_writ=
e_begin_pos,
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0(unsigned long) nfsi->layout.pnfs_writ=
e_end_pos);
> - =A0 =A0 =A0 spin_unlock(&nfsi->lo_lock);
> + =A0 =A0 =A0 unlock_current_layout(nfsi);
> =A0}
>
> =A0/* Unitialize a mountpoint in a layout driver */
> @@ -296,12 +299,27 @@ pnfs_unregister_layoutdriver(struct pnfs_layout=
driver_type *ld_type)
> =A0* pNFS client layout cache
> =A0*/
> =A0#if defined(CONFIG_SMP)
> +#define BUG_ON_LOCKED_LO(lo) \
> + =A0 =A0 =A0 BUG_ON(spin_is_locked(&PNFS_NFS_INODE(lo)->lo_lock))
> =A0#define BUG_ON_UNLOCKED_LO(lo) \
> =A0 =A0 =A0 =A0BUG_ON(!spin_is_locked(&PNFS_NFS_INODE(lo)->lo_lock))
> =A0#else /* CONFIG_SMP */
> +#define BUG_ON_LOCKED_LO(lo) do {} while (0)
> =A0#define BUG_ON_UNLOCKED_LO(lo) do {} while (0)
> =A0#endif /* CONFIG_SMP */
>
> +static inline void lock_current_layout(struct nfs_inode *nfsi)
> +{
> + =A0 =A0 =A0 BUG_ON_LOCKED_LO((&nfsi->layout));

I just ran into this in testing. This check causes problems.  If you
know it is already unlocked, you wouldn't have to "spin".

=46red

> + =A0 =A0 =A0 spin_lock(&nfsi->lo_lock);
> +}
> +
> +static inline void unlock_current_layout(struct nfs_inode *nfsi)
> +{
> + =A0 =A0 =A0 BUG_ON_UNLOCKED_LO((&nfsi->layout));
> + =A0 =A0 =A0 spin_unlock(&nfsi->lo_lock);
> +}
> +
> =A0/*
> =A0* get and lock nfsi->layout
> =A0*/
> @@ -310,10 +328,10 @@ get_lock_current_layout(struct nfs_inode *nfsi)
> =A0{
> =A0 =A0 =A0 =A0struct pnfs_layout_type *lo;
>
> + =A0 =A0 =A0 lock_current_layout(nfsi);
> =A0 =A0 =A0 =A0lo =3D &nfsi->layout;
> - =A0 =A0 =A0 spin_lock(&nfsi->lo_lock);
> =A0 =A0 =A0 =A0if (!lo->ld_data) {
> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 spin_unlock(&nfsi->lo_lock);
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 unlock_current_layout(nfsi);
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0return NULL;
> =A0 =A0 =A0 =A0}
>
> @@ -333,7 +351,12 @@ put_unlock_current_layout(struct pnfs_layout_typ=
e *lo)
> =A0 =A0 =A0 =A0BUG_ON_UNLOCKED_LO(lo);
> =A0 =A0 =A0 =A0BUG_ON(lo->refcount <=3D 0);
>
> - =A0 =A0 =A0 if (--lo->refcount =3D=3D 0 && list_empty(&lo->segs)) {
> + =A0 =A0 =A0 lo->refcount--;
> +
> + =A0 =A0 =A0 if (lo->refcount > 0)
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 goto out;
> +
> + =A0 =A0 =A0 if (list_empty(&lo->segs)) {
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0struct layoutdriver_io_operations *io_=
ops =3D
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0PNFS_LD_IO_OPS(lo);
>
> @@ -347,7 +370,8 @@ put_unlock_current_layout(struct pnfs_layout_type=
 *lo)
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0list_del_init(&nfsi->lo_inodes);
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0spin_unlock(&clp->cl_lock);
> =A0 =A0 =A0 =A0}
> - =A0 =A0 =A0 spin_unlock(&nfsi->lo_lock);
> +out:
> + =A0 =A0 =A0 unlock_current_layout(nfsi);
> =A0}
>
> =A0void
> @@ -356,7 +380,7 @@ pnfs_layout_release(struct pnfs_layout_type *lo, =
atomic_t *count,
> =A0{
> =A0 =A0 =A0 =A0struct nfs_inode *nfsi =3D PNFS_NFS_INODE(lo);
>
> - =A0 =A0 =A0 spin_lock(&nfsi->lo_lock);
> + =A0 =A0 =A0 lock_current_layout(nfsi);
> =A0 =A0 =A0 =A0if (range)
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0pnfs_free_layout(lo, range);
> =A0 =A0 =A0 =A0atomic_dec(count);
> @@ -375,6 +399,8 @@ pnfs_destroy_layout(struct nfs_inode *nfsi)
> =A0 =A0 =A0 =A0};
>
> =A0 =A0 =A0 =A0lo =3D get_lock_current_layout(nfsi);
> + =A0 =A0 =A0 if (!lo)
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 return;
> =A0 =A0 =A0 =A0pnfs_free_layout(lo, &range);
> =A0 =A0 =A0 =A0put_unlock_current_layout(lo);
> =A0}
> @@ -652,7 +678,7 @@ pnfs_return_layout_barrier(struct nfs_inode *nfsi=
,
> =A0 =A0 =A0 =A0struct pnfs_layout_segment *lseg;
> =A0 =A0 =A0 =A0bool ret =3D false;
>
> - =A0 =A0 =A0 spin_lock(&nfsi->lo_lock);
> + =A0 =A0 =A0 lock_current_layout(nfsi);
> =A0 =A0 =A0 =A0list_for_each_entry (lseg, &nfsi->layout.segs, fi_list=
) {
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0if (!should_free_lseg(lseg, range))
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0continue;
> @@ -666,7 +692,7 @@ pnfs_return_layout_barrier(struct nfs_inode *nfsi=
,
> =A0 =A0 =A0 =A0}
> =A0 =A0 =A0 =A0if (atomic_read(&nfsi->layout.lgetcount))
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0ret =3D true;
> - =A0 =A0 =A0 spin_unlock(&nfsi->lo_lock);
> + =A0 =A0 =A0 unlock_current_layout(nfsi);
>
> =A0 =A0 =A0 =A0dprintk("%s:Return %d\n", __func__, ret);
> =A0 =A0 =A0 =A0return ret;
> @@ -756,7 +782,7 @@ _pnfs_return_layout(struct inode *ino, struct nfs=
4_pnfs_layout_segment *range,
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0/* unlock w/o put rebalanced by eventu=
al call to
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 * pnfs_layout_release
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 */
> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 spin_unlock(&nfsi->lo_lock);
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 unlock_current_layout(nfsi);
>
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0if (pnfs_return_layout_barrier(nfsi, &=
arg)) {
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0dprintk("%s: waiting\n=
", __func__);
> @@ -887,7 +913,7 @@ static int pnfs_wait_schedule(void *word)
> =A0*
> =A0* Note: If successful, nfsi->lo_lock is taken and the caller
> =A0* must put and unlock current_layout by using put_unlock_current_l=
ayout()
> - * when the returned layout is released.
> + * directly or pnfs_layout_release() when the returned layout is rel=
eased.
> =A0*/
> =A0static struct pnfs_layout_type *
> =A0get_lock_alloc_layout(struct inode *ino)
> @@ -922,7 +948,7 @@ get_lock_alloc_layout(struct inode *ino)
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0struct nfs_client *clp=
 =3D NFS_SERVER(ino)->nfs_client;
>
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0/* must grab the layou=
t lock before the client lock */
> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 spin_lock(&nfsi->lo_loc=
k);
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 lock_current_layout(nfs=
i);
>
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0spin_lock(&clp->cl_loc=
k);
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0if (list_empty(&nfsi->=
lo_inodes))
> @@ -1038,10 +1064,10 @@ void drain_layoutreturns(struct pnfs_layout_t=
ype *lo)
> =A0 =A0 =A0 =A0while (atomic_read(&lo->lretcount)) {
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0struct nfs_inode *nfsi =3D PNFS_NFS_IN=
ODE(lo);
>
> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 spin_unlock(&nfsi->lo_lock);
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 unlock_current_layout(nfsi);
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0dprintk("%s: waiting\n", __func__);
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0wait_event(nfsi->lo_waitq, (atomic_rea=
d(&lo->lretcount) =3D=3D 0));
> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 spin_lock(&nfsi->lo_lock);
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 lock_current_layout(nfsi);
> =A0 =A0 =A0 =A0}
> =A0}
>
> @@ -1080,13 +1106,13 @@ pnfs_update_layout(struct inode *ino,
> =A0 =A0 =A0 =A0/* Check to see if the layout for the given range alre=
ady exists */
> =A0 =A0 =A0 =A0lseg =3D pnfs_has_layout(lo, &arg, take_ref, !take_ref=
);
> =A0 =A0 =A0 =A0if (lseg && !lseg->valid) {
> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 spin_unlock(&nfsi->lo_lock);
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 unlock_current_layout(nfsi);
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0if (take_ref)
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0put_lseg(lseg);
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0for (;;) {
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0prepare_to_wait(&nfsi-=
>lo_waitq, &__wait,
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0=
 =A0 =A0TASK_KILLABLE);
> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 spin_lock(&nfsi->lo_loc=
k);
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 lock_current_layout(nfs=
i);
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0lseg =3D pnfs_has_layo=
ut(lo, &arg, take_ref, !take_ref);
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0if (!lseg || lseg->val=
id)
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0break;
> @@ -1099,7 +1125,7 @@ pnfs_update_layout(struct inode *ino,
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0result=
 =3D -ERESTARTSYS;
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0break;
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0}
> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 spin_unlock(&nfsi->lo_l=
ock);
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 unlock_current_layout(n=
fsi);
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0schedule();
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0}
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0finish_wait(&nfsi->lo_waitq, &__wait);
> @@ -1136,7 +1162,7 @@ pnfs_update_layout(struct inode *ino,
> =A0 =A0 =A0 =A0/* Matching dec is done in .rpc_release (on non-error =
paths) */
> =A0 =A0 =A0 =A0atomic_inc(&lo->lgetcount);
> =A0 =A0 =A0 =A0/* Lose lock, but not reference, match this with pnfs_=
layout_release */
> - =A0 =A0 =A0 spin_unlock(&nfsi->lo_lock);
> + =A0 =A0 =A0 unlock_current_layout(nfsi);
>
> =A0 =A0 =A0 =A0result =3D get_layout(ino, ctx, &arg, lsegpp, lo);
> =A0out:
> @@ -1286,7 +1312,7 @@ pnfs_layout_process(struct nfs4_pnfs_layoutget =
*lgp)
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0*lgp->lsegpp =3D lseg;
> =A0 =A0 =A0 =A0}
>
> - =A0 =A0 =A0 spin_lock(&nfsi->lo_lock);
> + =A0 =A0 =A0 lock_current_layout(nfsi);
> =A0 =A0 =A0 =A0pnfs_insert_layout(lo, lseg);
>
> =A0 =A0 =A0 =A0if (res->return_on_close) {
> @@ -1297,7 +1323,7 @@ pnfs_layout_process(struct nfs4_pnfs_layoutget =
*lgp)
>
> =A0 =A0 =A0 =A0/* Done processing layoutget. Set the layout stateid *=
/
> =A0 =A0 =A0 =A0pnfs_set_layout_stateid(lo, &res->stateid);
> - =A0 =A0 =A0 spin_unlock(&nfsi->lo_lock);
> + =A0 =A0 =A0 unlock_current_layout(nfsi);
> =A0out:
> =A0 =A0 =A0 =A0return status;
> =A0}
> @@ -2212,7 +2238,7 @@ pnfs_layoutcommit_inode(struct inode *inode, in=
t sync)
> =A0 =A0 =A0 =A0if (!data)
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0return -ENOMEM;
>
> - =A0 =A0 =A0 spin_lock(&nfsi->lo_lock);
> + =A0 =A0 =A0 lock_current_layout(nfsi);
> =A0 =A0 =A0 =A0if (!nfsi->layout.layoutcommit_ctx)
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0goto out_unlock;
>
> @@ -2233,7 +2259,7 @@ pnfs_layoutcommit_inode(struct inode *inode, in=
t sync)
> =A0 =A0 =A0 =A0nfsi->layout.layoutcommit_ctx =3D NULL;
>
> =A0 =A0 =A0 =A0/* release lock on pnfs layoutcommit attrs */
> - =A0 =A0 =A0 spin_unlock(&nfsi->lo_lock);
> + =A0 =A0 =A0 unlock_current_layout(nfsi);
>
> =A0 =A0 =A0 =A0data->is_sync =3D sync;
> =A0 =A0 =A0 =A0status =3D pnfs4_proc_layoutcommit(data);
> @@ -2242,7 +2268,7 @@ out:
> =A0 =A0 =A0 =A0return status;
> =A0out_unlock:
> =A0 =A0 =A0 =A0pnfs_layoutcommit_free(data);
> - =A0 =A0 =A0 spin_unlock(&nfsi->lo_lock);
> + =A0 =A0 =A0 unlock_current_layout(nfsi);
> =A0 =A0 =A0 =A0goto out;
> =A0}
>
> --
> 1.6.2.5
>
> --
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