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 7389C23B63C; Sat, 7 Feb 2026 11:35:55 +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=1770464155; cv=none; b=NyHVtk4vqec2HZPiXZwgWQZsSx1+HZw6AZ4yHhI5YnZGeIs39b5OmFC5gfYys8mmLpCBsm/iNeO78TtHf2hY7zrbnZcWA+ZRU69pRagNKlbizVqK3o8EGvZJ+OZFS868mGckV8VsZ/R86hEapEvURxQDaJw8XnFmw5Pm0Ax4k10= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770464155; c=relaxed/simple; bh=INOjLccc8LtwpiyYYpCd7KKBkOG+vn21Gj8Mf2qQjdw=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=LZvsj7I/XtJQkG0ay586de4ot2Na2eZFshJJv9xl/0fzzBqYmBIFl3KKQ4mt8uh06THD1uaXwnoK58Slah4XpfPjo1oxHZumVr51kZT2J9vwCL3Okqx7/oh9D3V8PBaMtV8eNgicXTomeZYLJj1VPJSj30QtD9quglsUTtityJE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=V38WuvTQ; 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="V38WuvTQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DAF64C116D0; Sat, 7 Feb 2026 11:35:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770464155; bh=INOjLccc8LtwpiyYYpCd7KKBkOG+vn21Gj8Mf2qQjdw=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=V38WuvTQGvVS7Re0MKLEIX7Z6QJq9E3N9xNcdiMar3a6d7q0QcD9+Wkua8DwzLVAk f6UxIVDKDJ608cf7Uk8/eKhN2obOxQpxfF3SpX2YxWADYZjNW44Ivukgsznb9m/s2q d3m6FCTHBI1QcjNj8P3FutqkNJqtOujUk5lKVYoR/s/JtuPbGJBkwTIf35L4JOEGsv Lw5FOrculaNJGEAZS6ZOei8rWCpfF+qtcHKWPJrZso7VBRfWL3Y9S0dgSqVLWkdgk4 n11yownzQP6DDR50vicaDnYHCWGT1fTIloxl8/vU+1VbaR/tsf+IDfrkY752lM5Y+D T2oHjxJbImCcQ== Message-ID: Subject: Re: [PATCH v7 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: Sat, 07 Feb 2026 06:35:52 -0500 In-Reply-To: <20260207060940.2234728-1-dai.ngo@oracle.com> References: <20260207060940.2234728-1-dai.ngo@oracle.com> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV 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Fri, 2026-02-06 at 22:09 -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 | 15 ++- > fs/nfsd/blocklayout.c | 41 ++++++-- > fs/nfsd/nfs4layouts.c | 137 +++++++++++++++++++++++++- > fs/nfsd/nfs4state.c | 1 + > fs/nfsd/pnfs.h | 2 +- > fs/nfsd/state.h | 6 ++ > include/linux/filelock.h | 1 + > 8 files changed, 191 insertions(+), 14 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. > v5: > . take reference count on layout stateid before starting > fence worker. > . restore comments in nfsd4_scsi_fence_client and the > code that check for specific errors. > . cancel fence worker before freeing layout stateid. > . increase fence retry from 5 to 20. >=20 > NOTE: > I experimented with having the fence worker handle lease > disposal after fencing the client. However, this requires > the lease code to export the lease_dispose_list function, > and for the fence worker to acquire the flc_lock in order > to perform the disposal. This approach adds unnecessary > complexity and reduces code clarity, as it exposes internal > lease code details to the nfsd worker, which should not > be the case. >=20 > Instead, the lm_breaker_timedout operation should simply > notify the lease code about how to handle a lease that > times out during a lease break, rather than directly > manipulating the lease list. > v6: > . unlock the lease as soon as the fencing is done, so that > tasks waiting on it can proceed. >=20 > v7: > . Change to retry fencing on error forever by default. > . add module parameter option to allow the admim to specify > the maximun number of retries before giving up. >=20 > diff --git a/Documentation/filesystems/locking.rst b/Documentation/filesy= stems/locking.rst > index 04c7691e50e0..79bee9ae8bc3 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); > + bool (*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..0e77423cf000 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 +1532,18 @@ 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)) { > + /* > + * Consult the lease manager when a lease break times > + * out to determine whether the lease should be disposed > + * of. > + */ > + 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); > + } > } > } > =20 > diff --git a/fs/nfsd/blocklayout.c b/fs/nfsd/blocklayout.c > index 7ba9e2dd0875..b7030c91964c 100644 > --- a/fs/nfsd/blocklayout.c > +++ b/fs/nfsd/blocklayout.c > @@ -443,15 +443,33 @@ nfsd4_scsi_proc_layoutcommit(struct inode *inode, s= truct svc_rqst *rqstp, > return nfsd4_block_commit_blocks(inode, lcp, iomaps, nr_iomaps); > } > =20 > -static void > +/* > + * 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. > + * > + * The cl_fence_mutex ensures that the fence operation has been fully > + * completed, rather than just in progress, when returning from this > + * function. > + * > + * Return true if client was fenced otherwise return false. > + */ > +static bool > nfsd4_scsi_fence_client(struct nfs4_layout_stateid *ls, struct nfsd_file= *file) > { > struct nfs4_client *clp =3D ls->ls_stid.sc_client; > struct block_device *bdev =3D file->nf_file->f_path.mnt->mnt_sb->s_bdev= ; > int status; > + bool ret; > =20 > - if (nfsd4_scsi_fence_set(clp, bdev->bd_dev)) > - return; > + mutex_lock(&clp->cl_fence_mutex); > + if (nfsd4_scsi_fence_set(clp, bdev->bd_dev)) { > + mutex_unlock(&clp->cl_fence_mutex); > + return true; > + } > =20 > status =3D bdev->bd_disk->fops->pr_ops->pr_preempt(bdev, NFSD_MDS_PR_KE= Y, > nfsd4_scsi_pr_key(clp), > @@ -470,13 +488,22 @@ nfsd4_scsi_fence_client(struct nfs4_layout_stateid = *ls, struct nfsd_file *file) > * 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) > + switch (status) { > + case 0: > + case PR_STS_IOERR: > + case PR_STS_RESERVATION_CONFLICT: > + ret =3D true; > + break; > + default: > + /* retry-able and other errors */ > + ret =3D false; > nfsd4_scsi_fence_clear(clp, bdev->bd_dev); > + break; > + } > + mutex_unlock(&clp->cl_fence_mutex); > =20 > trace_nfsd_pnfs_fence(clp, bdev->bd_disk->disk_name, status); > + return ret; > } > =20 > const struct nfsd4_layout_ops scsi_layout_ops =3D { > diff --git a/fs/nfsd/nfs4layouts.c b/fs/nfsd/nfs4layouts.c > index ad7af8cfcf1f..c02b3219ebeb 100644 > --- a/fs/nfsd/nfs4layouts.c > +++ b/fs/nfsd/nfs4layouts.c > @@ -27,6 +27,25 @@ static struct kmem_cache *nfs4_layout_stateid_cache; > static const struct nfsd4_callback_ops nfsd4_cb_layout_ops; > static const struct lease_manager_operations nfsd4_layouts_lm_ops; > =20 > +/* > + * By default, if the server fails to fence a client, it retries the fen= cing > + * operation indefinitely to prevent data corruption. The admin needs to= take > + * the following actions to restore access to the file for other clients= : > + * > + * . shutdown or power off the client being fenced. > + * . manually expire the client to release all its state on the serve= r; > + * echo 'expire' > proc/fs/nfsd/clients/clientid/ctl'. > + * > + * The admim can control this behavior by setting nfsd4_fence_max_retrie= s > + * to specify the maximum number of retries. If the maximum is reached, = the > + * server gives up and removes the conflicting lease, allowing other cli= ents > + * to access the file. > + */ > +static int nfsd4_fence_max_retries =3D 0; /* default is retry forever *= / nit: globals are always initialized to 0. No need to explicitly do it here. > +module_param(nfsd4_fence_max_retries, int, 0644); > +MODULE_PARM_DESC(nfsd4_fence_max_retries, > + "Maximum retries for fencing operation, 0 is for retry forever."); > + > const struct nfsd4_layout_ops *nfsd4_layout_ops[LAYOUT_TYPE_MAX] =3D { > #ifdef CONFIG_NFSD_FLEXFILELAYOUT > [LAYOUT_FLEX_FILES] =3D &ff_layout_ops, > @@ -177,6 +196,13 @@ nfsd4_free_layout_stateid(struct nfs4_stid *stid) > =20 > trace_nfsd_layoutstate_free(&ls->ls_stid.sc_stateid); > =20 > + spin_lock(&ls->ls_lock); > + if (ls->ls_fence_in_progress) { > + spin_unlock(&ls->ls_lock); > + cancel_delayed_work_sync(&ls->ls_fence_work); > + } else > + spin_unlock(&ls->ls_lock); > + > spin_lock(&clp->cl_lock); > list_del_init(&ls->ls_perclnt); > spin_unlock(&clp->cl_lock); > @@ -271,6 +297,9 @@ nfsd4_alloc_layout_stateid(struct nfsd4_compound_stat= e *cstate, > list_add(&ls->ls_perfile, &fp->fi_lo_states); > spin_unlock(&fp->fi_lock); > =20 > + ls->ls_fence_in_progress =3D false; > + ls->ls_fenced =3D false; > + ls->ls_fence_retries =3D 0; > trace_nfsd_layoutstate_alloc(&ls->ls_stid.sc_stateid); > return ls; > } > @@ -747,11 +776,9 @@ 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 +809,112 @@ nfsd4_layout_lm_open_conflict(struct file *filp, i= nt arg) > return 0; > } > =20 > +static void > +nfsd4_layout_fence_worker(struct work_struct *work) > +{ > + 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); > + struct nfsd_file *nf; > + struct block_device *bdev; > + LIST_HEAD(dispose); > + > + spin_lock(&ls->ls_lock); > + if (list_empty(&ls->ls_layouts)) { > + spin_unlock(&ls->ls_lock); > +dispose: > + /* unlock the lease so that tasks waiting on it can proceed */ > + nfsd4_close_layout(ls); > + > + ls->ls_fenced =3D true; > + ls->ls_fence_in_progress =3D false; > + nfs4_put_stid(&ls->ls_stid); > + return; > + } > + spin_unlock(&ls->ls_lock); > + > + rcu_read_lock(); > + nf =3D nfsd_file_get(ls->ls_file); > + rcu_read_unlock(); > + if (!nf) > + goto dispose; > + > + if (nfsd4_layout_ops[ls->ls_layout_type]->fence_client(ls, nf)) { > + /* fenced ok */ > + nfsd_file_put(nf); > + goto dispose; > + } > + /* fence failed */ > + bdev =3D nf->nf_file->f_path.mnt->mnt_sb->s_bdev; > + nfsd_file_put(nf); > + > + pr_warn("%s: FENCE failed client[%pISpc] device[0x%x]\n", > + __func__, (struct sockaddr *)&ls->ls_stid.sc_client, > + bdev->bd_dev); > + if (nfsd4_fence_max_retries && > + ls->ls_fence_retries++ >=3D nfsd4_fence_max_retries) > + goto dispose; > + mod_delayed_work(system_dfl_wq, &ls->ls_fence_work, 1); > +} > + > +/** > + * nfsd4_layout_lm_breaker_timedout - The layout recall has timed out. > + * > + * @fl: file to check > + * > + * If the layout type supports a fence operation, schedule a worker to > + * fence the client from accessing the block device. > + * > + * This function runs under the protection of the spin_lock flc_lock. > + * At this time, the file_lease associated with the layout stateid is > + * on the flc_list. A reference count is incremented on the layout > + * stateid to prevent it from being freed while the fence orker is > + * executing. Once the fence worker finishes its operation, it releases > + * this reference. > + * > + * The fence worker continues to run until either the client has been > + * fenced or the layout becomes invalid. The layout can become invalid > + * as a result of a LAYOUTRETURN or when the CB_LAYOUT recall callback > + * has completed. > + * > + * 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; > + > + if ((!nfsd4_layout_ops[ls->ls_layout_type]->fence_client) || > + ls->ls_fenced) > + return true; > + if (ls->ls_fence_in_progress) > + return false; > + > + INIT_DELAYED_WORK(&ls->ls_fence_work, nfsd4_layout_fence_worker); > + > + /* > + * Make sure layout has not been returned yet before > + * taking a reference count on the layout stateid. > + */ > + spin_lock(&ls->ls_lock); > + if (list_empty(&ls->ls_layouts)) { > + spin_unlock(&ls->ls_lock); > + return true; > + } > + refcount_inc(&ls->ls_stid.sc_count); > + ls->ls_fence_in_progress =3D true; > + spin_unlock(&ls->ls_lock); > + > + mod_delayed_work(system_dfl_wq, &ls->ls_fence_work, 0); > + 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 98da72fc6067..bad91d1bfef3 100644 > --- a/fs/nfsd/nfs4state.c > +++ b/fs/nfsd/nfs4state.c > @@ -2387,6 +2387,7 @@ 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/pnfs.h b/fs/nfsd/pnfs.h > index db9af780438b..3a2f9e240e85 100644 > --- a/fs/nfsd/pnfs.h > +++ b/fs/nfsd/pnfs.h > @@ -38,7 +38,7 @@ struct nfsd4_layout_ops { > struct svc_rqst *rqstp, > struct nfsd4_layoutcommit *lcp); > =20 > - void (*fence_client)(struct nfs4_layout_stateid *ls, > + bool (*fence_client)(struct nfs4_layout_stateid *ls, > struct nfsd_file *file); > }; > =20 > diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h > index 713f55ef6554..be85c9fd6a68 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 > @@ -738,6 +739,11 @@ struct nfs4_layout_stateid { > stateid_t ls_recall_sid; > bool ls_recalled; > struct mutex ls_mutex; > + > + struct delayed_work ls_fence_work; > + int ls_fence_retries; > + bool ls_fence_in_progress; > + bool ls_fenced; > }; > =20 > static inline struct nfs4_layout_stateid *layoutstateid(struct nfs4_stid= *s) > 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 { Thanks, Dai. I think this one looks good. Reviewed-by: Jeff Layton