Re: [PATCH 10/18] nfsd: implement pNFS layout recalls

J. Bruce Fields
2015-01-06T17:25:17Z

On Tue, Jan 06, 2015 at 05:28:33PM +0100, Christoph Hellwig wrote:
> Add support to issue layout recalls to clients. For now we only support
> full-file recalls to get a simple and stable implementation. This allows
> to embedd a nfsd4_callback structure in the layout_state and thus avoid
> any memory allocations under spinlocks during a recall. For normal
> use cases that do not intent to share a single file between multiple
> clients this implementation is fully sufficient.
>
> To ensure layouts are recalled on local filesystem access each layout
> state registers a new FL_LAYOUT lease with the kernel file locking code,
> which filesystems that support pNFS exports that require recalls need
> to break on conflicting access patterns.
>
> The XDR code is based on the old pNFS server implementation by
> Andy Adamson, Benny Halevy, Boaz Harrosh, Dean Hildebrand, Fred Isaman,
> Marc Eshel, Mike Sager and Ricardo Labiaga.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> fs/nfsd/nfs4callback.c | 99 +++++++++++++++++++++++
> fs/nfsd/nfs4layouts.c | 214 ++++++++++++++++++++++++++++++++++++++++++++++++-
> fs/nfsd/nfs4proc.c | 4 +
> fs/nfsd/nfs4state.c | 1 +
> fs/nfsd/state.h | 6 ++
> fs/nfsd/xdr4cb.h | 7 ++
> 6 files changed, 330 insertions(+), 1 deletion(-)
>
> diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
> index 7cbdf1b..5827785 100644
> --- a/fs/nfsd/nfs4callback.c
> +++ b/fs/nfsd/nfs4callback.c
> @@ -546,6 +546,102 @@ out:
> return status;
> }
>
> +#ifdef CONFIG_NFSD_PNFS
> +/*
> + * CB_LAYOUTRECALL4args
> + *
> + * struct layoutrecall_file4 {
> + * nfs_fh4 lor_fh;
> + * offset4 lor_offset;
> + * length4 lor_length;
> + * stateid4 lor_stateid;
> + * };
> + *
> + * union layoutrecall4 switch(layoutrecall_type4 lor_recalltype) {
> + * case LAYOUTRECALL4_FILE:
> + * layoutrecall_file4 lor_layout;
> + * case LAYOUTRECALL4_FSID:
> + * fsid4 lor_fsid;
> + * case LAYOUTRECALL4_ALL:
> + * void;
> + * };
> + *
> + * struct CB_LAYOUTRECALL4args {
> + * layouttype4 clora_type;
> + * layoutiomode4 clora_iomode;
> + * bool clora_changed;
> + * layoutrecall4 clora_recall;
> + * };
> + */
> +static void encode_cb_layout4args(struct xdr_stream *xdr,
> + const struct nfs4_layout_stateid *ls,
> + struct nfs4_cb_compound_hdr *hdr)
> +{
> + __be32 *p;
> +
> + BUG_ON(hdr->minorversion == 0);
> +
> + p = xdr_reserve_space(xdr, 5 * 4);
> + *p++ = cpu_to_be32(OP_CB_LAYOUTRECALL);
> + *p++ = cpu_to_be32(ls->ls_layout_type);
> + *p++ = cpu_to_be32(IOMODE_ANY);
> + *p++ = cpu_to_be32(1);
> + *p = cpu_to_be32(RETURN_FILE);
> +
> + encode_nfs_fh4(xdr, &ls->ls_stid.sc_file->fi_fhandle);
> +
> + p = xdr_reserve_space(xdr, 2 * 8);
> + p = xdr_encode_hyper(p, 0);
> + xdr_encode_hyper(p, NFS4_MAX_UINT64);
> +
> + encode_stateid4(xdr, &ls->ls_recall_sid);
> +
> + hdr->nops++;
> +}
> +
> +static void nfs4_xdr_enc_cb_layout(struct rpc_rqst *req,
> + struct xdr_stream *xdr,
> + const struct nfsd4_callback *cb)
> +{
> + const struct nfs4_layout_stateid *ls =
> + container_of(cb, struct nfs4_layout_stateid, ls_recall);
> + struct nfs4_cb_compound_hdr hdr = {
> + .ident = 0,
> + .minorversion = cb->cb_minorversion,
> + };
> +
> + encode_cb_compound4args(xdr, &hdr);
> + encode_cb_sequence4args(xdr, cb, &hdr);
> + encode_cb_layout4args(xdr, ls, &hdr);
> + encode_cb_nops(&hdr);
> +}
> +
> +static int nfs4_xdr_dec_cb_layout(struct rpc_rqst *rqstp,
> + struct xdr_stream *xdr,
> + struct nfsd4_callback *cb)
> +{
> + struct nfs4_cb_compound_hdr hdr;
> + enum nfsstat4 nfserr;
> + int status;
> +
> + status = decode_cb_compound4res(xdr, &hdr);
> + if (unlikely(status))
> + goto out;
> + if (cb) {
> + status = decode_cb_sequence4res(xdr, cb);
> + if (unlikely(status))
> + goto out;
> + }
> + status = decode_cb_op_status(xdr, OP_CB_LAYOUTRECALL, &nfserr);
> + if (unlikely(status))
> + goto out;
> + if (unlikely(nfserr != NFS4_OK))
> + status = nfs_cb_stat_to_errno(nfserr);
> +out:
> + return status;
> +}
> +#endif /* CONFIG_NFSD_PNFS */
> +
> /*
> * RPC procedure tables
> */
> @@ -563,6 +659,9 @@ out:
> static struct rpc_procinfo nfs4_cb_procedures[] = {
> PROC(CB_NULL, NULL, cb_null, cb_null),
> PROC(CB_RECALL, COMPOUND, cb_recall, cb_recall),
> +#ifdef CONFIG_NFSD_PNFS
> + PROC(CB_LAYOUT, COMPOUND, cb_layout, cb_layout),
> +#endif
> };
>
> static struct rpc_version nfs_cb_version4 = {
> diff --git a/fs/nfsd/nfs4layouts.c b/fs/nfsd/nfs4layouts.c
> index 0753ed8..72a12ca 100644
> --- a/fs/nfsd/nfs4layouts.c
> +++ b/fs/nfsd/nfs4layouts.c
> @@ -1,8 +1,11 @@
> /*
> * Copyright (c) 2014 Christoph Hellwig.
> */
> +#include <linux/kmod.h>
> +#include <linux/file.h>
> #include <linux/jhash.h>
> #include <linux/sched.h>
> +#include <linux/sunrpc/addr.h>
>
> #include "pnfs.h"
> #include "netns.h"
> @@ -18,6 +21,9 @@ struct nfs4_layout {
> static struct kmem_cache *nfs4_layout_cache;
> static struct kmem_cache *nfs4_layout_stateid_cache;
>
> +static struct nfsd4_callback_ops nfsd4_cb_layout_ops;
> +static const struct lock_manager_operations nfsd4_layouts_lm_ops;
> +
> const struct nfsd4_layout_ops *nfsd4_layout_ops[LAYOUT_TYPE_MAX] = {
> };
>
> @@ -126,9 +132,42 @@ nfsd4_free_layout_stateid(struct nfs4_stid *stid)
> list_del_init(&ls->ls_perfile);
> spin_unlock(&fp->fi_lock);
>
> + vfs_setlease(ls->ls_file, F_UNLCK, NULL, (void **)&ls);
> + fput(ls->ls_file);
> +
> + if (ls->ls_recalled)
> + atomic_dec(&ls->ls_stid.sc_file->fi_lo_recalls);
> +
> kmem_cache_free(nfs4_layout_stateid_cache, ls);
> }
>
> +static int
> +nfsd4_layout_setlease(struct nfs4_layout_stateid *ls)
> +{
> + struct file_lock *fl;
> + int status;
> +
> + fl = locks_alloc_lock();
> + if (!fl)
> + return -ENOMEM;
> + locks_init_lock(fl);
> + fl->fl_lmops = &nfsd4_layouts_lm_ops;
> + fl->fl_flags = FL_LAYOUT;
> + fl->fl_type = F_RDLCK;
> + fl->fl_end = OFFSET_MAX;
> + fl->fl_owner = ls;
> + fl->fl_pid = current->tgid;
> + fl->fl_file = ls->ls_file;
> +
> + status = vfs_setlease(fl->fl_file, fl->fl_type, &fl, NULL);
> + if (status) {
> + locks_free_lock(fl);
> + return status;
> + }
> + BUG_ON(fl != NULL);
> + return 0;
> +}
> +
> static struct nfs4_layout_stateid *
> nfsd4_alloc_layout_stateid(struct nfsd4_compound_state *cstate,
> struct nfs4_stid *parent, u32 layout_type)
> @@ -151,6 +190,20 @@ nfsd4_alloc_layout_stateid(struct nfsd4_compound_state *cstate,
> spin_lock_init(&ls->ls_lock);
> INIT_LIST_HEAD(&ls->ls_layouts);
> ls->ls_layout_type = layout_type;
> + nfsd4_init_cb(&ls->ls_recall, clp, &nfsd4_cb_layout_ops,
> + NFSPROC4_CLNT_CB_LAYOUT);
> +
> + if (parent->sc_type == NFS4_DELEG_STID)
> + ls->ls_file = get_file(fp->fi_deleg_file);
> + else
> + ls->ls_file = find_any_file(fp);
> + BUG_ON(!ls->ls_file);
> +
> + if (nfsd4_layout_setlease(ls)) {
> + put_nfs4_file(fp);
> + kmem_cache_free(nfs4_layout_stateid_cache, ls);
> + return NULL;
> + }
>
> spin_lock(&clp->cl_lock);
> stp->sc_type = NFS4_LAYOUT_STID;
> @@ -214,6 +267,27 @@ out:
> return status;
> }
>
> +static void
> +nfsd4_recall_file_layout(struct nfs4_layout_stateid *ls)
> +{
> + spin_lock(&ls->ls_lock);
> + if (ls->ls_recalled)
> + goto out_unlock;
> +
> + ls->ls_recalled = true;
> + atomic_inc(&ls->ls_stid.sc_file->fi_lo_recalls);
> + if (list_empty(&ls->ls_layouts))
> + goto out_unlock;
> +
> + atomic_inc(&ls->ls_stid.sc_count);
> + update_stateid(&ls->ls_stid.sc_stateid);
> + memcpy(&ls->ls_recall_sid, &ls->ls_stid.sc_stateid, sizeof(stateid_t));
> + nfsd4_run_cb(&ls->ls_recall);
> +
> +out_unlock:
> + spin_unlock(&ls->ls_lock);
> +}
> +
> static inline u64
> layout_end(struct nfsd4_layout_seg *seg)
> {
> @@ -257,18 +331,44 @@ layouts_try_merge(struct nfsd4_layout_seg *lo, struct nfsd4_layout_seg *new)
> return true;
> }
>
> +static __be32
> +nfsd4_recall_conflict(struct nfs4_layout_stateid *ls)
> +{
> + struct nfs4_file *fp = ls->ls_stid.sc_file;
> + struct nfs4_layout_stateid *l, *n;
> + __be32 nfserr = nfs_ok;
> +
> + assert_spin_locked(&fp->fi_lock);
> +
> + list_for_each_entry_safe(l, n, &fp->fi_lo_states, ls_perfile) {
> + if (l != ls) {
> + nfsd4_recall_file_layout(l);
> + nfserr = nfserr_recallconflict;
> + }
> + }
> +
> + return nfserr;
> +}
> +
> __be32
> nfsd4_insert_layout(struct nfsd4_layoutget *lgp, struct nfs4_layout_stateid *ls)
> {
> struct nfsd4_layout_seg *seg = &lgp->lg_seg;
> + struct nfs4_file *fp = ls->ls_stid.sc_file;
> struct nfs4_layout *lp, *new = NULL;
> + __be32 nfserr;
>
> + spin_lock(&fp->fi_lock);
> + nfserr = nfsd4_recall_conflict(ls);
> + if (nfserr)
> + goto out;
> spin_lock(&ls->ls_lock);
> list_for_each_entry(lp, &ls->ls_layouts, lo_perstate) {
> if (layouts_try_merge(&lp->lo_seg, seg))
> goto done;
> }
> spin_unlock(&ls->ls_lock);
> + spin_unlock(&fp->fi_lock);
>
> new = kmem_cache_alloc(nfs4_layout_cache, GFP_KERNEL);
> if (!new)
> @@ -276,6 +376,10 @@ nfsd4_insert_layout(struct nfsd4_layoutget *lgp, struct nfs4_layout_stateid *ls)
> memcpy(&new->lo_seg, seg, sizeof(lp->lo_seg));
> new->lo_state = ls;
>
> + spin_lock(&fp->fi_lock);
> + nfserr = nfsd4_recall_conflict(ls);
> + if (nfserr)
> + goto out;
> spin_lock(&ls->ls_lock);
> list_for_each_entry(lp, &ls->ls_layouts, lo_perstate) {
> if (layouts_try_merge(&lp->lo_seg, seg))
> @@ -289,9 +393,11 @@ done:
> update_stateid(&ls->ls_stid.sc_stateid);
> memcpy(&lgp->lg_sid, &ls->ls_stid.sc_stateid, sizeof(stateid_t));
> spin_unlock(&ls->ls_lock);
> +out:
> + spin_unlock(&fp->fi_lock);
> if (new)
> kmem_cache_free(nfs4_layout_cache, new);
> - return nfs_ok;
> + return nfserr;
> }
>
> static void
> @@ -447,6 +553,112 @@ nfsd4_return_all_file_layouts(struct nfs4_client *clp, struct nfs4_file *fp)
> nfsd4_free_layouts(&reaplist);
> }
>
> +static void
> +nfsd4_cb_layout_fail(struct nfs4_layout_stateid *ls)
> +{
> + struct nfs4_client *clp = ls->ls_stid.sc_client;
> + char addr_str[INET6_ADDRSTRLEN];
> + static char *envp[] = {
> + "HOME=/",
> + "TERM=linux",
> + "PATH=/sbin:/usr/sbin:/bin:/usr/bin",
> + NULL
> + };
> + char *argv[8];
> + int error;
> +
> + rpc_ntop((struct sockaddr *)&clp->cl_addr, addr_str, sizeof(addr_str));

This bothers me a little: cl_addr is just the address that the
exchange_id came from. In theory there's no one-to-one relationship
between NFSv4 clients and IP addresses. Is it likely the iscsi traffic
could use a different interface than the MDS traffic?

If this is the best we can do, then maybe this should at least be
documented.

--b.

> +
> + printk(KERN_WARNING
> + "nfsd: client %s failed to respond to layout recall. "
> + " Fencing..\n", addr_str);
> +
> + argv[0] = "/sbin/nfsd-recall-failed";
> + argv[1] = addr_str;
> + argv[2] = ls->ls_file->f_path.mnt->mnt_sb->s_id;
> + argv[3] = NULL;
> +
> + error = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC);
> + if (error) {
> + printk(KERN_ERR "nfsd: fence failed for client %s: %d!\n",
> + addr_str, error);
> + }
> +}
> +
> +static int
> +nfsd4_cb_layout_done(struct nfsd4_callback *cb, struct rpc_task *task)
> +{
> + struct nfs4_layout_stateid *ls =
> + container_of(cb, struct nfs4_layout_stateid, ls_recall);
> + LIST_HEAD(reaplist);
> +
> + switch (task->tk_status) {
> + case 0:
> + return 1;
> + case -NFS4ERR_NOMATCHING_LAYOUT:
> + task->tk_status = 0;
> + return 1;
> + case -NFS4ERR_DELAY:
> + /* Poll the client until it's done with the layout */
> + /* FIXME: cap number of retries.
> + * The pnfs standard states that we need to only expire
> + * the client after at-least "lease time" .eg lease-time * 2
> + * when failing to communicate a recall
> + */
> + rpc_delay(task, HZ/100); /* 10 mili-seconds */
> + return 0;
> + default:
> + /*
> + * Unknown error or non-responding client, we'll need to fence.
> + */
> + nfsd4_cb_layout_fail(ls);
> + return -1;
> + }
> +}
> +
> +static void
> +nfsd4_cb_layout_release(struct nfsd4_callback *cb)
> +{
> + struct nfs4_layout_stateid *ls =
> + container_of(cb, struct nfs4_layout_stateid, ls_recall);
> + LIST_HEAD(reaplist);
> +
> + nfsd4_return_all_layouts(ls, &reaplist);
> + nfsd4_free_layouts(&reaplist);
> + nfs4_put_stid(&ls->ls_stid);
> +}
> +
> +static struct nfsd4_callback_ops nfsd4_cb_layout_ops = {
> + .done = nfsd4_cb_layout_done,
> + .release = nfsd4_cb_layout_release,
> +};
> +
> +static bool
> +nfsd4_layout_lm_break(struct file_lock *fl)
> +{
> + /*
> + * We don't want the locks code to timeout the lease for us;
> + * we'll remove it ourself if a layout isn't returned
> + * in time:
> + */
> + fl->fl_break_time = 0;
> + nfsd4_recall_file_layout(fl->fl_owner);
> + return false;
> +}
> +
> +static int
> +nfsd4_layout_lm_change(struct file_lock **onlist, int arg,
> + struct list_head *dispose)
> +{
> + BUG_ON(!(arg & F_UNLCK));
> + return lease_modify(onlist, arg, dispose);
> +}
> +
> +static const struct lock_manager_operations nfsd4_layouts_lm_ops = {
> + .lm_break = nfsd4_layout_lm_break,
> + .lm_change = nfsd4_layout_lm_change,
> +};
> +
> int
> nfsd4_init_pnfs(void)
> {
> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> index b813913..c051d5b 100644
> --- a/fs/nfsd/nfs4proc.c
> +++ b/fs/nfsd/nfs4proc.c
> @@ -1301,6 +1301,10 @@ nfsd4_layoutget(struct svc_rqst *rqstp,
> if (nfserr)
> goto out;
>
> + nfserr = nfserr_recallconflict;
> + if (atomic_read(&ls->ls_stid.sc_file->fi_lo_recalls))
> + goto out_put_stid;
> +
> nfserr = ops->proc_layoutget(current_fh->fh_dentry->d_inode,
> current_fh, lgp);
> if (nfserr)
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index eb972e6..1450b57 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -3070,6 +3070,7 @@ static void nfsd4_init_file(struct knfsd_fh *fh, unsigned int hashval,
> memset(fp->fi_access, 0, sizeof(fp->fi_access));
> #ifdef CONFIG_NFSD_PNFS
> INIT_LIST_HEAD(&fp->fi_lo_states);
> + atomic_set(&fp->fi_lo_recalls, 0);
> #endif
> hlist_add_head_rcu(&fp->fi_hash, &file_hashtbl[hashval]);
> }
> diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
> index 5f66b7f..4f3bfeb 100644
> --- a/fs/nfsd/state.h
> +++ b/fs/nfsd/state.h
> @@ -502,6 +502,7 @@ struct nfs4_file {
> bool fi_had_conflict;
> #ifdef CONFIG_NFSD_PNFS
> struct list_head fi_lo_states;
> + atomic_t fi_lo_recalls;
> #endif
> };
>
> @@ -542,6 +543,10 @@ struct nfs4_layout_stateid {
> spinlock_t ls_lock;
> struct list_head ls_layouts;
> u32 ls_layout_type;
> + struct file *ls_file;
> + struct nfsd4_callback ls_recall;
> + stateid_t ls_recall_sid;
> + bool ls_recalled;
> };
>
> static inline struct nfs4_layout_stateid *layoutstateid(struct nfs4_stid *s)
> @@ -556,6 +561,7 @@ static inline struct nfs4_layout_stateid *layoutstateid(struct nfs4_stid *s)
> enum nfsd4_cb_op {
> NFSPROC4_CLNT_CB_NULL = 0,
> NFSPROC4_CLNT_CB_RECALL,
> + NFSPROC4_CLNT_CB_LAYOUT,
> NFSPROC4_CLNT_CB_SEQUENCE,
> };
>
> diff --git a/fs/nfsd/xdr4cb.h b/fs/nfsd/xdr4cb.h
> index c5c55df..c47f6fd 100644
> --- a/fs/nfsd/xdr4cb.h
> +++ b/fs/nfsd/xdr4cb.h
> @@ -21,3 +21,10 @@
> #define NFS4_dec_cb_recall_sz (cb_compound_dec_hdr_sz + \
> cb_sequence_dec_sz + \
> op_dec_sz)
> +#define NFS4_enc_cb_layout_sz (cb_compound_enc_hdr_sz + \
> + cb_sequence_enc_sz + \
> + 1 + 3 + \
> + enc_nfs4_fh_sz + 4)
> +#define NFS4_dec_cb_layout_sz (cb_compound_dec_hdr_sz + \
> + cb_sequence_dec_sz + \
> + op_dec_sz)
> --
> 1.9.1