From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9838937105F; Wed, 28 Jan 2026 18:01:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769623266; cv=none; b=RmxlZAIkk6dmzuoc+jf7yu0QK/EHAD7paofFRREQLlCffeb0eXT0gOFVcHlREPJuUO3d7dJWNj3Tt9aToBDDkMAVwuyCnOyKL/Ie+CRXtLudLNNU5aUj5oCoPypL70LDd5jLIAndXAy46AgEb8z8Vxd3jVixU7XWVLPRQOQVHyk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769623266; c=relaxed/simple; bh=8HCTFdaEET777TsS1Bk4+idpe2LB4hcuablG4zozL7E=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=u3wMrJUmYQ172J3y3a85S9JdftPccVnxbAB+589VuRNhg9ce7UOQJXNEHj4bs3K7ysMyBhqWiHb5+bAc2KFONCKR2MwgXjhfvArI11+A+eCvrHPvZ8ddO/4NJV3nmsyYd3rY8Nrmm2j0TrkLAru80Pg71458ZhPfnsMoom5TkC0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LMj4Liyg; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="LMj4Liyg" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 95368C4CEF1; Wed, 28 Jan 2026 18:01:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1769623265; bh=8HCTFdaEET777TsS1Bk4+idpe2LB4hcuablG4zozL7E=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=LMj4Liyg/Jty+K8/gvo5cWbZvtTzOIQMFsqWnbCnYrdCIcGaDJdz7Lq2Ht+iHejI4 CXrhb/uIHvARtiOAFUabcVQugjGlM7AfL0d7aAM7CbIoyLRWAGSvaIAq+pLSDPkFkP GTAYqjTQIQgDmLx8aEMlwyM9gfXrbBvFRuTrvMIbtepvj0HvLHnYZe+hrtEvRtVNjm DhiRJyCxvoJ9B8tSxfK2fXjMy/t+UjmTdqAyTW8pN+izXRwdNxCTNH4ygUayWwwg7d yqtzh61BEyAMGb0bWrkLkEhF5f4ttkHkc7FkAxQYVH6MrIlYKsnHFGYti6IwaYdD0E hOAaTDdE26MgA== Message-ID: Subject: Re: [PATCH v4 1/1] NFSD: Enforce Timeout on Layout Recall and Integrate Lease Manager Fencing From: Jeff Layton To: Dai Ngo , chuck.lever@oracle.com, neil@brown.name, okorniev@redhat.com, tom@talpey.com, hch@lst.de, alex.aring@gmail.com, viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz Cc: linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org Date: Wed, 28 Jan 2026 13:01:03 -0500 In-Reply-To: References: <20260127005013.552805-1-dai.ngo@oracle.com> <5d2288d77498582f78152bdb411222930a7e5978.camel@kernel.org> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV 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Wed, 2026-01-28 at 09:25 -0800, Dai Ngo wrote: > On 1/27/26 9:54 AM, Jeff Layton wrote: > > On Mon, 2026-01-26 at 16:50 -0800, Dai Ngo wrote: > > > When a layout conflict triggers a recall, enforcing a timeout is > > > necessary to prevent excessive nfsd threads from being blocked in > > > __break_lease ensuring the server continues servicing incoming > > > requests efficiently. > > >=20 > > > This patch introduces a new function to lease_manager_operations: > > >=20 > > > lm_breaker_timedout: Invoked when a lease recall times out and is > > > about to be disposed of. This function enables the lease manager > > > to inform the caller whether the file_lease should remain on the > > > flc_list or be disposed of. > > >=20 > > > For the NFSD lease manager, this function now handles layout recall > > > timeouts. If the layout type supports fencing and the client has not > > > been fenced, a fence operation is triggered to prevent the client > > > from accessing the block device. > > >=20 > > > While the fencing operation is in progress, the conflicting file_leas= e > > > remains on the flc_list until fencing is complete. This guarantees > > > that no other clients can access the file, and the client with > > > exclusive access is properly blocked before disposal. > > >=20 > > > Signed-off-by: Dai Ngo > > > --- > > > Documentation/filesystems/locking.rst | 2 + > > > fs/locks.c | 10 +++- > > > fs/nfsd/blocklayout.c | 38 ++++++------- > > > fs/nfsd/nfs4layouts.c | 79 ++++++++++++++++++++++++= +-- > > > fs/nfsd/nfs4state.c | 1 + > > > fs/nfsd/state.h | 6 ++ > > > include/linux/filelock.h | 1 + > > > 7 files changed, 110 insertions(+), 27 deletions(-) > > >=20 > > > v2: > > > . Update Subject line to include fencing operation. > > > . Allow conflicting lease to remain on flc_list until fencing > > > is complete. > > > . Use system worker to perform fencing operation asynchronously. > > > . Use nfs4_stid.sc_count to ensure layout stateid remains > > > valid before starting the fencing operation, nfs4_stid.sc_coun= t > > > is released after fencing operation is complete. > > > . Rework nfsd4_scsi_fence_client to: > > > . wait until fencing to complete before exiting. > > > . wait until fencing in progress to complete before > > > checking the NFSD_MDS_PR_FENCED flag. > > > . Remove lm_need_to_retry from lease_manager_operations. > > > v3: > > > . correct locking requirement in locking.rst. > > > . add max retry count to fencing operation. > > > . add missing nfs4_put_stid in nfsd4_layout_fence_worker. > > > . remove special-casing of FL_LAYOUT in lease_modify. > > > . remove lease_want_dispose. > > > . move lm_breaker_timedout call to time_out_leases. > > > v4: > > > . only increment ls_fence_retry_cnt after successfully > > > schedule new work in nfsd4_layout_lm_breaker_timedout. > > >=20 > > > diff --git a/Documentation/filesystems/locking.rst b/Documentation/fi= lesystems/locking.rst > > > index 04c7691e50e0..a339491f02e4 100644 > > > --- a/Documentation/filesystems/locking.rst > > > +++ b/Documentation/filesystems/locking.rst > > > @@ -403,6 +403,7 @@ prototypes:: > > > bool (*lm_breaker_owns_lease)(struct file_lock *); > > > bool (*lm_lock_expirable)(struct file_lock *); > > > void (*lm_expire_lock)(void); > > > + void (*lm_breaker_timedout)(struct file_lease *); > > > =20 > > > locking rules: > > > =20 > > > @@ -417,6 +418,7 @@ lm_breaker_owns_lease: yes no no > > > lm_lock_expirable yes no no > > > lm_expire_lock no no yes > > > lm_open_conflict yes no no > > > +lm_breaker_timedout yes no no > > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D = =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D =3D=3D=3D=3D=3D=3D=3D=3D=3D > > > =20 > > > buffer_head > > > diff --git a/fs/locks.c b/fs/locks.c > > > index 46f229f740c8..1b63aa704598 100644 > > > --- a/fs/locks.c > > > +++ b/fs/locks.c > > > @@ -1524,6 +1524,7 @@ static void time_out_leases(struct inode *inode= , struct list_head *dispose) > > > { > > > struct file_lock_context *ctx =3D inode->i_flctx; > > > struct file_lease *fl, *tmp; > > > + bool remove =3D true; > > > =20 > > > lockdep_assert_held(&ctx->flc_lock); > > > =20 > > > @@ -1531,8 +1532,13 @@ static void time_out_leases(struct inode *inod= e, struct list_head *dispose) > > > trace_time_out_leases(inode, fl); > > > if (past_time(fl->fl_downgrade_time)) > > > lease_modify(fl, F_RDLCK, dispose); > > > - if (past_time(fl->fl_break_time)) > > > - lease_modify(fl, F_UNLCK, dispose); > > > + > > > + if (past_time(fl->fl_break_time)) { > > > + if (fl->fl_lmops && fl->fl_lmops->lm_breaker_timedout) > > > + remove =3D fl->fl_lmops->lm_breaker_timedout(fl); > > > + if (remove) > > > + lease_modify(fl, F_UNLCK, dispose); > > I'd not bother with the return code to lm_breaker_timedout. > >=20 > > Make it void return and have it call lease_modify itself before > > returning in the cases where you have it returning true. If the > > operation isn't defined then just do the lease_modify here like we > > always have. >=20 > The first call to lm_breaker_timedout schedules the fence worker so > fencing is not done yet. If lm_breaker_timedout return to time_out_leases > without any return value then lease_modify is called to remove the lease. >=20 > Am i missing something? >=20 > -Dai >=20 if (fl->fl_lmops && fl->fl_lmops->lm_breaker_timedout) fl->fl_lmops->lm_breaker_timedout(fl); else lease_modify(fl, F_UNLCK, dispose); ... the lm_breaker_timedout() function (or the workqueue job it spawns) is then responsible for calling lease_modify() at the appropriate time. In most cases you're going to need to queue a workqueue job to fence, and you don't want to clear out the lease until after it's done. > >=20 > > > + } > > > } > > > } > > > =20 > > > diff --git a/fs/nfsd/blocklayout.c b/fs/nfsd/blocklayout.c > > > index 7ba9e2dd0875..69d3889df302 100644 > > > --- a/fs/nfsd/blocklayout.c > > > +++ b/fs/nfsd/blocklayout.c > > > @@ -443,6 +443,14 @@ nfsd4_scsi_proc_layoutcommit(struct inode *inode= , struct svc_rqst *rqstp, > > > return nfsd4_block_commit_blocks(inode, lcp, iomaps, nr_iomaps); > > > } > > > =20 > > > +/* > > > + * Perform the fence operation to prevent the client from accessing = the > > > + * block device. If a fence operation is already in progress, wait f= or > > > + * it to complete before checking the NFSD_MDS_PR_FENCED flag. Once = the > > > + * operation is complete, check the flag. If NFSD_MDS_PR_FENCED is s= et, > > > + * update the layout stateid by setting the ls_fenced flag to indica= te > > > + * that the client has been fenced. > > > + */ > > > static void > > > nfsd4_scsi_fence_client(struct nfs4_layout_stateid *ls, struct nfsd= _file *file) > > > { > > > @@ -450,31 +458,23 @@ nfsd4_scsi_fence_client(struct nfs4_layout_stat= eid *ls, struct nfsd_file *file) > > > struct block_device *bdev =3D file->nf_file->f_path.mnt->mnt_sb->s= _bdev; > > > int status; > > > =20 > > > - if (nfsd4_scsi_fence_set(clp, bdev->bd_dev)) > > > + mutex_lock(&clp->cl_fence_mutex); > > > + if (nfsd4_scsi_fence_set(clp, bdev->bd_dev)) { > > > + ls->ls_fenced =3D true; > > > + mutex_unlock(&clp->cl_fence_mutex); > > > + nfs4_put_stid(&ls->ls_stid); > > > return; > > > + } > > > =20 > > I don't understand what this new mutex is protecting, and this all > > seems overly complex. If feels kind of like you want nfsd to be driving > > the fencing retries, but I don't think we really do. Here's what I'd > > do. > >=20 > > I'd just make ->fence_client a bool or int return, and have it indicate > > whether the client was successfully fenced or not. If it was > > successfully fenced, then have the caller call lease_modify() to remove > > the lease.=C2=A0If it wasn't successfully fenced, have the caller (the > > workqueue job) requeue itself if you want to retry. If the caller is > > ready to give up, then call lease_modify() on it and remove it (and > > probably throw a pr_warn()). > >=20 > > > status =3D bdev->bd_disk->fops->pr_ops->pr_preempt(bdev, NFSD_MDS_= PR_KEY, > > > nfsd4_scsi_pr_key(clp), > > > PR_EXCLUSIVE_ACCESS_REG_ONLY, true); > > > - /* > > > - * Reset to allow retry only when the command could not have > > > - * reached the device. Negative status means a local error > > > - * (e.g., -ENOMEM) prevented the command from being sent. > > > - * PR_STS_PATH_FAILED, PR_STS_PATH_FAST_FAILED, and > > > - * PR_STS_RETRY_PATH_FAILURE indicate transport path failures > > > - * before device delivery. > > > - * > > > - * For all other errors, the command may have reached the device > > > - * and the preempt may have succeeded. Avoid resetting, since > > > - * retrying a successful preempt returns PR_STS_IOERR or > > > - * PR_STS_RESERVATION_CONFLICT, which would cause an infinite > > > - * retry loop. > > > - */ > > > - if (status < 0 || > > > - status =3D=3D PR_STS_PATH_FAILED || > > > - status =3D=3D PR_STS_PATH_FAST_FAILED || > > > - status =3D=3D PR_STS_RETRY_PATH_FAILURE) > > > + if (status) > > > nfsd4_scsi_fence_clear(clp, bdev->bd_dev); > > > + else > > > + ls->ls_fenced =3D true; > > > + mutex_unlock(&clp->cl_fence_mutex); > > > + nfs4_put_stid(&ls->ls_stid); > > > =20 > > > trace_nfsd_pnfs_fence(clp, bdev->bd_disk->disk_name, status); > > > } > > > diff --git a/fs/nfsd/nfs4layouts.c b/fs/nfsd/nfs4layouts.c > > > index ad7af8cfcf1f..1c498f3cd059 100644 > > > --- a/fs/nfsd/nfs4layouts.c > > > +++ b/fs/nfsd/nfs4layouts.c > > > @@ -222,6 +222,29 @@ nfsd4_layout_setlease(struct nfs4_layout_stateid= *ls) > > > return 0; > > > } > > > =20 > > > +static void > > > +nfsd4_layout_fence_worker(struct work_struct *work) > > > +{ > > > + struct nfsd_file *nf; > > > + struct delayed_work *dwork =3D to_delayed_work(work); > > > + struct nfs4_layout_stateid *ls =3D container_of(dwork, > > > + struct nfs4_layout_stateid, ls_fence_work); > > > + u32 type; > > > + > > > + rcu_read_lock(); > > > + nf =3D nfsd_file_get(ls->ls_file); > > > + rcu_read_unlock(); > > > + if (!nf) { > > > + nfs4_put_stid(&ls->ls_stid); > > > + return; > > > + } > > > + > > > + type =3D ls->ls_layout_type; > > > + if (nfsd4_layout_ops[type]->fence_client) > > > + nfsd4_layout_ops[type]->fence_client(ls, nf); > > If you make fence_client an int/bool return, then you could just > > requeue this job to try it again. > >=20 > > > + nfsd_file_put(nf); > > > +} > > > + > > > static struct nfs4_layout_stateid * > > > nfsd4_alloc_layout_stateid(struct nfsd4_compound_state *cstate, > > > struct nfs4_stid *parent, u32 layout_type) > > > @@ -271,6 +294,10 @@ nfsd4_alloc_layout_stateid(struct nfsd4_compound= _state *cstate, > > > list_add(&ls->ls_perfile, &fp->fi_lo_states); > > > spin_unlock(&fp->fi_lock); > > > =20 > > > + INIT_DELAYED_WORK(&ls->ls_fence_work, nfsd4_layout_fence_worker); > > > + ls->ls_fenced =3D false; > > > + ls->ls_fence_retry_cnt =3D 0; > > > + > > > trace_nfsd_layoutstate_alloc(&ls->ls_stid.sc_stateid); > > > return ls; > > > } > > > @@ -708,9 +735,10 @@ nfsd4_cb_layout_done(struct nfsd4_callback *cb, = struct rpc_task *task) > > > rcu_read_unlock(); > > > if (fl) { > > > ops =3D nfsd4_layout_ops[ls->ls_layout_type]; > > > - if (ops->fence_client) > > > + if (ops->fence_client) { > > > + refcount_inc(&ls->ls_stid.sc_count); > > > ops->fence_client(ls, fl); > > > - else > > > + } else > > > nfsd4_cb_layout_fail(ls, fl); > > > nfsd_file_put(fl); > > > } > > > @@ -747,11 +775,9 @@ static bool > > > nfsd4_layout_lm_break(struct file_lease *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: > > > + * Enforce break lease timeout to prevent NFSD > > > + * thread from hanging in __break_lease. > > > */ > > > - fl->fl_break_time =3D 0; > > > nfsd4_recall_file_layout(fl->c.flc_owner); > > > return false; > > > } > > > @@ -782,10 +808,51 @@ nfsd4_layout_lm_open_conflict(struct file *filp= , int arg) > > > return 0; > > > } > > > =20 > > > +/** > > > + * nfsd4_layout_lm_breaker_timedout - The layout recall has timed ou= t. > > > + * If the layout type supports a fence operation, schedule a worker = to > > > + * fence the client from accessing the block device. > > > + * > > > + * @fl: file to check > > > + * > > > + * Return true if the file lease should be disposed of by the caller= ; > > > + * otherwise, return false. > > > + */ > > > +static bool > > > +nfsd4_layout_lm_breaker_timedout(struct file_lease *fl) > > > +{ > > > + struct nfs4_layout_stateid *ls =3D fl->c.flc_owner; > > > + bool ret; > > > + > > > + if (!nfsd4_layout_ops[ls->ls_layout_type]->fence_client) > > > + return true; > > > + if (ls->ls_fenced || ls->ls_fence_retry_cnt >=3D LO_MAX_FENCE_RETRY= ) > > > + return true; > > > + > > > + if (work_busy(&ls->ls_fence_work.work)) > > > + return false; > > > + /* Schedule work to do the fence operation */ > > > + ret =3D mod_delayed_work(system_dfl_wq, &ls->ls_fence_work, 0); > > > + if (!ret) { > > > + /* > > > + * If there is no pending work, mod_delayed_work queues > > > + * new task. While fencing is in progress, a reference > > > + * count is added to the layout stateid to ensure its > > > + * validity. This reference count is released once fencing > > > + * has been completed. > > > + */ > > > + refcount_inc(&ls->ls_stid.sc_count); > > > + ++ls->ls_fence_retry_cnt; > > > + return true; > > The cases where the fencing didn't work after too many retries, or the > > job couldn't be queued should probably get a pr_warn or something. The > > admin needs to know that data corruption is possible and that they > > might need to nuke the client manually. > >=20 > > > + } > > > + return false; > > > +} > > > + > > > static const struct lease_manager_operations nfsd4_layouts_lm_ops = =3D { > > > .lm_break =3D nfsd4_layout_lm_break, > > > .lm_change =3D nfsd4_layout_lm_change, > > > .lm_open_conflict =3D nfsd4_layout_lm_open_conflict, > > > + .lm_breaker_timedout =3D nfsd4_layout_lm_breaker_timedout, > > > }; > > > =20 > > > int > > > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c > > > index 583c13b5aaf3..a57fa3318362 100644 > > > --- a/fs/nfsd/nfs4state.c > > > +++ b/fs/nfsd/nfs4state.c > > > @@ -2385,6 +2385,7 @@ static struct nfs4_client *alloc_client(struct = xdr_netobj name, > > > #endif > > > #ifdef CONFIG_NFSD_SCSILAYOUT > > > xa_init(&clp->cl_dev_fences); > > > + mutex_init(&clp->cl_fence_mutex); > > > #endif > > > INIT_LIST_HEAD(&clp->async_copies); > > > spin_lock_init(&clp->async_lock); > > > diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h > > > index 713f55ef6554..57e54dfb406c 100644 > > > --- a/fs/nfsd/state.h > > > +++ b/fs/nfsd/state.h > > > @@ -529,6 +529,7 @@ struct nfs4_client { > > > time64_t cl_ra_time; > > > #ifdef CONFIG_NFSD_SCSILAYOUT > > > struct xarray cl_dev_fences; > > > + struct mutex cl_fence_mutex; > > > #endif > > > }; > > > =20 > > > @@ -738,8 +739,13 @@ struct nfs4_layout_stateid { > > > stateid_t ls_recall_sid; > > > bool ls_recalled; > > > struct mutex ls_mutex; > > > + struct delayed_work ls_fence_work; > > > + bool ls_fenced; > > > + int ls_fence_retry_cnt; > > > }; > > > =20 > > > +#define LO_MAX_FENCE_RETRY 5 > > > + > > > static inline struct nfs4_layout_stateid *layoutstateid(struct nfs4= _stid *s) > > > { > > > return container_of(s, struct nfs4_layout_stateid, ls_stid); > > > diff --git a/include/linux/filelock.h b/include/linux/filelock.h > > > index 2f5e5588ee07..13b9c9f04589 100644 > > > --- a/include/linux/filelock.h > > > +++ b/include/linux/filelock.h > > > @@ -50,6 +50,7 @@ struct lease_manager_operations { > > > void (*lm_setup)(struct file_lease *, void **); > > > bool (*lm_breaker_owns_lease)(struct file_lease *); > > > int (*lm_open_conflict)(struct file *, int); > > > + bool (*lm_breaker_timedout)(struct file_lease *fl); > > > }; > > > =20 > > > struct lock_manager { --=20 Jeff Layton