On Wed, May 19, 2021 at 04:44:20PM -0400, Dai Ngo wrote:
> Currently the source's export is mounted and unmounted on every
> inter-server copy operation. This patch is an enhancement to delay
> the unmount of the source export for a certain period of time to
> eliminate the mount and unmount overhead on subsequent copy operations.
>
> After a copy operation completes, a work entry is added to the
> delayed unmount list with an expiration time. This list is serviced
> by the laundromat thread to unmount the export of the expired entries.
> Each time the export is being used again, its expiration time is
> extended and the entry is re-inserted to the tail of the list.
>
> The unmount task and the mount operation of the copy request are
> synced to make sure the export is not unmounted while it's being
> used.
>
> Signed-off-by: Dai Ngo <dai.ngo@xxxxxxxxxx>
> ---
> fs/nfsd/netns.h | 6 +++
> fs/nfsd/nfs4proc.c | 105 ++++++++++++++++++++++++++++++++++++++++++++++--
> fs/nfsd/nfs4state.c | 71 ++++++++++++++++++++++++++++++++
> fs/nfsd/nfsd.h | 4 ++
> fs/nfsd/nfssvc.c | 3 ++
> include/linux/nfs_ssc.h | 14 +++++++
> 6 files changed, 199 insertions(+), 4 deletions(-)
>
> diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h
> index a75abeb1e698..935c1028c217 100644
> --- a/fs/nfsd/netns.h
> +++ b/fs/nfsd/netns.h
> @@ -176,6 +176,12 @@ struct nfsd_net {
> unsigned int longest_chain_cachesize;
>
> struct shrinker nfsd_reply_cache_shrinker;
> +
> + /* tracking server-to-server copy mounts */
> + spinlock_t nfsd_ssc_lock;
> + struct list_head nfsd_ssc_mount_list;
> + wait_queue_head_t nfsd_ssc_waitq;
> +
> /* utsname taken from the process that starts the server */
> char nfsd_name[UNX_MAXNODENAME+1];
> };
> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> index f4ce93d7f26e..9fa5b0a73814 100644
> --- a/fs/nfsd/nfs4proc.c
> +++ b/fs/nfsd/nfs4proc.c
> @@ -55,6 +55,13 @@ module_param(inter_copy_offload_enable, bool, 0644);
> MODULE_PARM_DESC(inter_copy_offload_enable,
> "Enable inter server to server copy offload. Default: false");
>
> +#ifdef CONFIG_NFSD_V4_2_INTER_SSC
> +static int nfsd4_ssc_umount_timeout = 900000; /* default to 15 mins */
> +module_param(nfsd4_ssc_umount_timeout, int, 0644);
> +MODULE_PARM_DESC(nfsd4_ssc_umount_timeout,
> + "idle msecs before unmount export from source server");
> +#endif
> +
> #ifdef CONFIG_NFSD_V4_SECURITY_LABEL
> #include <linux/security.h>
>
> @@ -1181,6 +1188,11 @@ nfsd4_interssc_connect(struct nl4_server *nss, struct svc_rqst *rqstp,
> char *ipaddr, *dev_name, *raw_data;
> int len, raw_len;
> __be32 status = nfserr_inval;
> + struct nfsd4_ssc_umount_item *ni = 0;
> + struct nfsd4_ssc_umount_item *work = NULL;
> + struct nfsd4_ssc_umount_item *tmp;
> + struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
> + DEFINE_WAIT(wait);
>
> naddr = &nss->u.nl4_addr;
> tmp_addrlen = rpc_uaddr2sockaddr(SVC_NET(rqstp), naddr->addr,
> @@ -1229,12 +1241,65 @@ nfsd4_interssc_connect(struct nl4_server *nss, struct svc_rqst *rqstp,
> goto out_free_rawdata;
> snprintf(dev_name, len + 5, "%s%s%s:/", startsep, ipaddr, endsep);
>
> + work = kzalloc(sizeof(*work), GFP_KERNEL);
> +try_again:
> + spin_lock(&nn->nfsd_ssc_lock);
> + list_for_each_entry_safe(ni, tmp, &nn->nfsd_ssc_mount_list, nsui_list) {
> + if (strncmp(ni->nsui_ipaddr, ipaddr, sizeof(ni->nsui_ipaddr)))
> + continue;
> + /* found a match */
> + if (ni->nsui_busy) {
> + /* wait - and try again */
> + prepare_to_wait(&nn->nfsd_ssc_waitq, &wait,
> + TASK_INTERRUPTIBLE);
> + spin_unlock(&nn->nfsd_ssc_lock);
> +
> + /* allow 20secs for mount/unmount for now - revisit */
> + if (signal_pending(current) ||
> + (schedule_timeout(20*HZ) == 0)) {
> + status = nfserr_eagain;
> + kfree(work);
> + goto out_free_devname;
> + }
> + finish_wait(&nn->nfsd_ssc_waitq, &wait);
> + goto try_again;
> + }
> + ss_mnt = ni->nsui_vfsmount;
> + refcount_inc(&ni->nsui_refcnt);
> + spin_unlock(&nn->nfsd_ssc_lock);
> + kfree(work);
> + goto out_done;
> + }
> + /* create new entry, set busy, insert list, clear busy after mount */
> + if (work) {
> + strncpy(work->nsui_ipaddr, ipaddr, sizeof(work->nsui_ipaddr));
> + refcount_set(&work->nsui_refcnt, 2);
> + work->nsui_busy = true;
> + list_add_tail(&work->nsui_list, &nn->nfsd_ssc_mount_list);
> + }
> + spin_unlock(&nn->nfsd_ssc_lock);
> +
We try to keep functions short. This new code looks reasonably
self-contained, could you put it in its own function?
> /* Use an 'internal' mount: SB_KERNMOUNT -> MNT_INTERNAL */
> ss_mnt = vfs_kern_mount(type, SB_KERNMOUNT, dev_name, raw_data);
> module_put(type->owner);
> - if (IS_ERR(ss_mnt))
> + if (IS_ERR(ss_mnt)) {
> + if (work) {
> + spin_lock(&nn->nfsd_ssc_lock);
> + list_del(&work->nsui_list);
> + wake_up_all(&nn->nfsd_ssc_waitq);
> + spin_unlock(&nn->nfsd_ssc_lock);
> + kfree(work);
> + }
> goto out_free_devname;
> -
> + }
> + if (work) {
> + spin_lock(&nn->nfsd_ssc_lock);
> + work->nsui_vfsmount = ss_mnt;
> + work->nsui_busy = false;
> + wake_up_all(&nn->nfsd_ssc_waitq);
> + spin_unlock(&nn->nfsd_ssc_lock);
> + }
Ditto.--b.
> +out_done:
> status = 0;
> *mount = ss_mnt;
>
> @@ -1301,10 +1366,42 @@ static void
> nfsd4_cleanup_inter_ssc(struct vfsmount *ss_mnt, struct nfsd_file *src,
> struct nfsd_file *dst)
> {
> + bool found = false;
> + long timeout;
> + struct nfsd4_ssc_umount_item *tmp;
> + struct nfsd4_ssc_umount_item *ni = 0;
> + struct nfsd_net *nn = net_generic(dst->nf_net, nfsd_net_id);
> +
> nfs42_ssc_close(src->nf_file);
> - fput(src->nf_file);
> nfsd_file_put(dst);
> - mntput(ss_mnt);
> + fput(src->nf_file);
> +
> + if (!nn) {
> + mntput(ss_mnt);
> + return;
> + }
> + spin_lock(&nn->nfsd_ssc_lock);
> + timeout = msecs_to_jiffies(nfsd4_ssc_umount_timeout);
> + list_for_each_entry_safe(ni, tmp, &nn->nfsd_ssc_mount_list, nsui_list) {
> + if (ni->nsui_vfsmount->mnt_sb == ss_mnt->mnt_sb) {
> + list_del(&ni->nsui_list);
> + /*
> + * vfsmount can be shared by multiple exports,
> + * decrement refcnt. If the count drops to 1 it
> + * will be unmounted when nsui_expire expires.
> + */
> + refcount_dec(&ni->nsui_refcnt);
> + ni->nsui_expire = jiffies + timeout;
> + list_add_tail(&ni->nsui_list, &nn->nfsd_ssc_mount_list);
> + found = true;
> + break;
> + }
> + }
> + spin_unlock(&nn->nfsd_ssc_lock);
> + if (!found) {
> + mntput(ss_mnt);
> + return;
> + }
Ditto here, let's keep nfsd4_cleanup_inter_ssc short and call out to
this new code.
--b.
> }
>
> #else /* CONFIG_NFSD_V4_2_INTER_SSC */
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index b517a8794400..2484b59a3c29 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -44,6 +44,7 @@
> #include <linux/jhash.h>
> #include <linux/string_helpers.h>
> #include <linux/fsnotify.h>
> +#include <linux/nfs_ssc.h>
> #include "xdr4.h"
> #include "xdr4cb.h"
> #include "vfs.h"
> @@ -5457,6 +5458,69 @@ static bool state_expired(struct laundry_time *lt, time64_t last_refresh)
> return false;
> }
>
> +#ifdef CONFIG_NFSD_V4_2_INTER_SSC
> +void nfsd4_ssc_init_umount_work(struct nfsd_net *nn)
> +{
> + spin_lock_init(&nn->nfsd_ssc_lock);
> + INIT_LIST_HEAD(&nn->nfsd_ssc_mount_list);
> + init_waitqueue_head(&nn->nfsd_ssc_waitq);
> +}
> +EXPORT_SYMBOL_GPL(nfsd4_ssc_init_umount_work);
> +
> +/*
> + * This is called when nfsd is being shutdown, after all inter_ssc
> + * cleanup were done, to destroy the ssc delayed unmount list.
> + */
> +static void nfsd4_ssc_shutdown_umount(struct nfsd_net *nn)
> +{
> + struct nfsd4_ssc_umount_item *ni = 0;
> + struct nfsd4_ssc_umount_item *tmp;
> +
> + spin_lock(&nn->nfsd_ssc_lock);
> + list_for_each_entry_safe(ni, tmp, &nn->nfsd_ssc_mount_list, nsui_list) {
> + list_del(&ni->nsui_list);
> + spin_unlock(&nn->nfsd_ssc_lock);
> + mntput(ni->nsui_vfsmount);
> + kfree(ni);
> + spin_lock(&nn->nfsd_ssc_lock);
> + }
> + spin_unlock(&nn->nfsd_ssc_lock);
> +}
> +
> +static void nfsd4_ssc_expire_umount(struct nfsd_net *nn)
> +{
> + bool do_wakeup = false;
> + struct nfsd4_ssc_umount_item *ni = 0;
> + struct nfsd4_ssc_umount_item *tmp;
> +
> + spin_lock(&nn->nfsd_ssc_lock);
> + list_for_each_entry_safe(ni, tmp, &nn->nfsd_ssc_mount_list, nsui_list) {
> + if (time_after(jiffies, ni->nsui_expire)) {
> + if (refcount_read(&ni->nsui_refcnt) > 1)
> + continue;
> +
> + /* mark being unmount */
> + ni->nsui_busy = true;
> + spin_unlock(&nn->nfsd_ssc_lock);
> + mntput(ni->nsui_vfsmount);
> + spin_lock(&nn->nfsd_ssc_lock);
> +
> + /* waiters need to start from begin of list */
> + list_del(&ni->nsui_list);
> + kfree(ni);
> +
> + /* wakeup ssc_connect waiters */
> + do_wakeup = true;
> + continue;
> + }
> + break;
> + }
> + if (do_wakeup)
> + wake_up_all(&nn->nfsd_ssc_waitq);
> + spin_unlock(&nn->nfsd_ssc_lock);
> +}
> +#endif
> +
> static time64_t
> nfs4_laundromat(struct nfsd_net *nn)
> {
> @@ -5568,6 +5632,10 @@ nfs4_laundromat(struct nfsd_net *nn)
> list_del_init(&nbl->nbl_lru);
> free_blocked_lock(nbl);
> }
> +#ifdef CONFIG_NFSD_V4_2_INTER_SSC
> + /* service the server-to-server copy delayed unmount list */
> + nfsd4_ssc_expire_umount(nn);
> +#endif
> out:
> return max_t(time64_t, lt.new_timeo, NFSD_LAUNDROMAT_MINTIMEOUT);
> }
> @@ -7486,6 +7554,9 @@ nfs4_state_shutdown_net(struct net *net)
>
> nfsd4_client_tracking_exit(net);
> nfs4_state_destroy_net(net);
> +#ifdef CONFIG_NFSD_V4_2_INTER_SSC
> + nfsd4_ssc_shutdown_umount(nn);
> +#endif
> }
>
> void
> diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
> index 14dbfa75059d..9664303afdaf 100644
> --- a/fs/nfsd/nfsd.h
> +++ b/fs/nfsd/nfsd.h
> @@ -484,6 +484,10 @@ static inline bool nfsd_attrs_supported(u32 minorversion, const u32 *bmval)
> extern int nfsd4_is_junction(struct dentry *dentry);
> extern int register_cld_notifier(void);
> extern void unregister_cld_notifier(void);
> +#ifdef CONFIG_NFSD_V4_2_INTER_SSC
> +extern void nfsd4_ssc_init_umount_work(struct nfsd_net *nn);
> +#endif
> +
> #else /* CONFIG_NFSD_V4 */
> static inline int nfsd4_is_junction(struct dentry *dentry)
> {
> diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
> index dd5d69921676..ccb59e91011b 100644
> --- a/fs/nfsd/nfssvc.c
> +++ b/fs/nfsd/nfssvc.c
> @@ -403,6 +403,9 @@ static int nfsd_startup_net(struct net *net, const struct cred *cred)
> if (ret)
> goto out_filecache;
>
> +#ifdef CONFIG_NFSD_V4_2_INTER_SSC
> + nfsd4_ssc_init_umount_work(nn);
> +#endif
> nn->nfsd_net_up = true;
> return 0;
>
> diff --git a/include/linux/nfs_ssc.h b/include/linux/nfs_ssc.h
> index f5ba0fbff72f..222ae8883e85 100644
> --- a/include/linux/nfs_ssc.h
> +++ b/include/linux/nfs_ssc.h
> @@ -8,6 +8,7 @@
> */
>
> #include <linux/nfs_fs.h>
> +#include <linux/sunrpc/svc.h>
>
> extern struct nfs_ssc_client_ops_tbl nfs_ssc_client_tbl;
>
> @@ -52,6 +53,19 @@ static inline void nfs42_ssc_close(struct file *filep)
> if (nfs_ssc_client_tbl.ssc_nfs4_ops)
> (*nfs_ssc_client_tbl.ssc_nfs4_ops->sco_close)(filep);
> }
> +
> +struct nfsd4_ssc_umount_item {
> + struct list_head nsui_list;
> + bool nsui_busy;
> + /*
> + * nsui_refcnt inited to 2, 1 on list and 1 for consumer. Entry
> + * is removed when refcnt drops to 1 and nsui_expire expires.
> + */
> + refcount_t nsui_refcnt;
> + unsigned long nsui_expire;
> + struct vfsmount *nsui_vfsmount;
> + char nsui_ipaddr[RPC_MAX_ADDRBUFLEN];
> +};
> #endif
>
> /*
> --
> 2.9.5
