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 EFD0125CC74; Tue, 27 Jan 2026 17:54:25 +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=1769536466; cv=none; b=L1vLRkt55ZN2FLM8QSdKv5yelPT8frXq/2uvi5YfmaPceJF8ERUCjfrgcGqDyZS7v5pIpPjD8alh3qWAAsH6p/I+Eahn7/yQjhClrE2uTJrAv46FYUsU8iVSHh9/74erXXONxiyexa+Ap4XsA0cvMfM0TmwGPmk8OOONo+zYgQ4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769536466; c=relaxed/simple; bh=+TpQiso8+Mc5uOWPKO2vvxlLvyPF5R4SZOAV0KBfANw=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=lCHdMrZEBHpB2yYTOcqY/hxf29Jyk5zhW0gPt9sEvj8KNgxHlFAlpaT2deN+xyjEhqKty6L3oQLrqmy2Qf8kC7oTlwnY8XNy2JeSC/FL5s1b4fjH46GMp9Ogo2UPjMpE2YqjbTWk/CzeF4DR0WcYDGsQprOMhWlHPdY0gc5redI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=lbPb+l17; 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="lbPb+l17" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 627A8C116C6; Tue, 27 Jan 2026 17:54:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1769536465; bh=+TpQiso8+Mc5uOWPKO2vvxlLvyPF5R4SZOAV0KBfANw=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=lbPb+l17mI0AJ3c1NiC7kU4zokhO6FC9dKndZ/CqO5FKJqLoIVvacEsa3+XRlo9LE 4f9oxnFuTM+iV8a9lP5JLaqXLBaECxGZve9nGrlCGNkyqaSlYszvxwYHG6/ifqLVY+ gn52y4wqLeew6ImdSkTE6un9uNewAwYPM7CVarBxA5dt0R/p9a62ZBXE3Bg6uo8aOY 2ThtmYQlaMTCrWf0w4BfeoT3YrzHCrWulEkq2ZEF/1Nz3oq2A/BjtyfZa9dAbD5gUf zwBHXVe+uhlqyUUeYYkViDp39IgDomcFWvfhlnlmslth9L/y6wzb2QichQrKtwknRy JJMAhR39V6T3g== Message-ID: <5d2288d77498582f78152bdb411222930a7e5978.camel@kernel.org> 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: Tue, 27 Jan 2026 12:54:23 -0500 In-Reply-To: <20260127005013.552805-1-dai.ngo@oracle.com> References: <20260127005013.552805-1-dai.ngo@oracle.com> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv 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linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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_lease > 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_count > 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/filesy= stems/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, st= ruct 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 *inode, s= truct 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. 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 > 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, st= ruct 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 for > + * 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 set, > + * update the layout stateid by setting the ls_fenced flag to indicate > + * 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_stateid = *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. 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()). > status =3D bdev->bd_disk->fops->pr_ops->pr_preempt(bdev, NFSD_MDS_PR_KE= Y, > 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. > + 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_sta= te *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, stru= ct 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, in= t arg) > return 0; > } > =20 > +/** > + * nfsd4_layout_lm_breaker_timedout - The layout recall has timed out. > + * 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. > + } > + 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