diff mbox series

[1/7] lockd: introduce safe async lock op

Message ID 20230823213352.1971009-2-aahringo@redhat.com (mailing list archive)
State New, archived
Headers show
Series lockd: dlm: async lock request changes | expand

Commit Message

Alexander Aring Aug. 23, 2023, 9:33 p.m. UTC
This patch reverts mostly commit 40595cdc93ed ("nfs: block notification
on fs with its own ->lock") and introduces an EXPORT_OP_SAFE_ASYNC_LOCK
export flag to signal that the "own ->lock" implementation supports
async lock requests. The only main user is DLM that is used by GFS2 and
OCFS2 filesystem. Those implement their own lock() implementation and
return FILE_LOCK_DEFERRED as return value. Since commit 40595cdc93ed
("nfs: block notification on fs with its own ->lock") the DLM
implementation were never updated. This patch should prepare for DLM
to set the EXPORT_OP_SAFE_ASYNC_LOCK export flag and update the DLM
plock implementation regarding to it.

Acked-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 fs/lockd/svclock.c       |  5 ++---
 fs/nfsd/nfs4state.c      | 13 ++++++++++---
 include/linux/exportfs.h |  8 ++++++++
 3 files changed, 20 insertions(+), 6 deletions(-)

Comments

Chuck Lever III Aug. 25, 2023, 5:21 p.m. UTC | #1
On Wed, Aug 23, 2023 at 05:33:46PM -0400, Alexander Aring wrote:
> This patch reverts mostly commit 40595cdc93ed ("nfs: block notification
> on fs with its own ->lock") and introduces an EXPORT_OP_SAFE_ASYNC_LOCK
> export flag to signal that the "own ->lock" implementation supports
> async lock requests. The only main user is DLM that is used by GFS2 and
> OCFS2 filesystem. Those implement their own lock() implementation and
> return FILE_LOCK_DEFERRED as return value. Since commit 40595cdc93ed
> ("nfs: block notification on fs with its own ->lock") the DLM
> implementation were never updated. This patch should prepare for DLM
> to set the EXPORT_OP_SAFE_ASYNC_LOCK export flag and update the DLM
> plock implementation regarding to it.
> 
> Acked-by: Jeff Layton <jlayton@kernel.org>
> Signed-off-by: Alexander Aring <aahringo@redhat.com>
> ---
>  fs/lockd/svclock.c       |  5 ++---
>  fs/nfsd/nfs4state.c      | 13 ++++++++++---
>  include/linux/exportfs.h |  8 ++++++++
>  3 files changed, 20 insertions(+), 6 deletions(-)

I'm starting to look at these. Just so you know, it's too late for
inclusion in v6.6, but I think we can get these into shape for v6.7.

More below.


> diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
> index c43ccdf28ed9..6e3b230e8317 100644
> --- a/fs/lockd/svclock.c
> +++ b/fs/lockd/svclock.c
> @@ -470,9 +470,7 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
>  	    struct nlm_host *host, struct nlm_lock *lock, int wait,
>  	    struct nlm_cookie *cookie, int reclaim)
>  {
> -#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
>  	struct inode		*inode = nlmsvc_file_inode(file);
> -#endif
>  	struct nlm_block	*block = NULL;
>  	int			error;
>  	int			mode;
> @@ -486,7 +484,8 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
>  				(long long)lock->fl.fl_end,
>  				wait);
>  
> -	if (nlmsvc_file_file(file)->f_op->lock) {
> +	if (!export_op_support_safe_async_lock(inode->i_sb->s_export_op,
> +					       nlmsvc_file_file(file)->f_op)) {
>  		async_block = wait;
>  		wait = 0;
>  	}
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 3aefbad4cc09..14ca06424ff1 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -7430,6 +7430,7 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>  	struct nfsd4_blocked_lock *nbl = NULL;
>  	struct file_lock *file_lock = NULL;
>  	struct file_lock *conflock = NULL;
> +	struct super_block *sb;
>  	__be32 status = 0;
>  	int lkflg;
>  	int err;
> @@ -7451,6 +7452,7 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>  		dprintk("NFSD: nfsd4_lock: permission denied!\n");
>  		return status;
>  	}
> +	sb = cstate->current_fh.fh_dentry->d_sb;
>  
>  	if (lock->lk_is_new) {
>  		if (nfsd4_has_session(cstate))
> @@ -7502,7 +7504,9 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>  	fp = lock_stp->st_stid.sc_file;
>  	switch (lock->lk_type) {
>  		case NFS4_READW_LT:
> -			if (nfsd4_has_session(cstate))
> +			if (nfsd4_has_session(cstate) ||
> +			    export_op_support_safe_async_lock(sb->s_export_op,
> +							      nf->nf_file->f_op))
>  				fl_flags |= FL_SLEEP;
>  			fallthrough;
>  		case NFS4_READ_LT:
> @@ -7514,7 +7518,9 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>  			fl_type = F_RDLCK;
>  			break;
>  		case NFS4_WRITEW_LT:
> -			if (nfsd4_has_session(cstate))
> +			if (nfsd4_has_session(cstate) ||
> +			    export_op_support_safe_async_lock(sb->s_export_op,
> +							      nf->nf_file->f_op))
>  				fl_flags |= FL_SLEEP;
>  			fallthrough;
>  		case NFS4_WRITE_LT:
> @@ -7542,7 +7548,8 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>  	 * for file locks), so don't attempt blocking lock notifications
>  	 * on those filesystems:
>  	 */
> -	if (nf->nf_file->f_op->lock)
> +	if (!export_op_support_safe_async_lock(sb->s_export_op,
> +					       nf->nf_file->f_op))
>  		fl_flags &= ~FL_SLEEP;
>  
>  	nbl = find_or_allocate_block(lock_sop, &fp->fi_fhandle, nn);
> diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h
> index 11fbd0ee1370..10358a93cdc1 100644
> --- a/include/linux/exportfs.h
> +++ b/include/linux/exportfs.h
> @@ -3,6 +3,7 @@
>  #define LINUX_EXPORTFS_H 1
>  
>  #include <linux/types.h>
> +#include <linux/fs.h>
>  
>  struct dentry;
>  struct iattr;
> @@ -224,9 +225,16 @@ struct export_operations {
>  						  atomic attribute updates
>  						*/
>  #define EXPORT_OP_FLUSH_ON_CLOSE	(0x20) /* fs flushes file data on close */
> +#define EXPORT_OP_SAFE_ASYNC_LOCK	(0x40) /* fs can do async lock request */

We haven't been good about this recently, but the addition of new
EXPORT_OP flags need to be accompanied by updates to
Documentation/filesystems/nfs/exporting.rst.

I will see about adding documentation for other recent flags, but
please include an update to exporting.rst with this patch.

I'm not sure we need _SAFE_ in the flag name. Would
EXPORT_OP_ASYNC_LOCK be OK with you?


>  	unsigned long	flags;
>  };
>  
> +static inline bool export_op_support_safe_async_lock(const struct export_operations *export_ops,
> +						     const struct file_operations *f_op)
> +{
> +	return (export_ops->flags & EXPORT_OP_SAFE_ASYNC_LOCK) || !f_op->lock;
> +}
> +

I'd like some cosmetic changes to this API, since this seems to be
the first utility function for checking EXPORT_OP flags.

- The function name is unwieldy. How about exportfs_lock_op_is_async() ?

- Break up the long lines. It's OK with me if the return value type
  is left on a different line than the function name and parameters.

- This function is globally visible, so a kdoc comment is needed.

- The f_op->lock check is common to all the call sites, but it is
  not at all related to the export AFAICT. Can it be removed from
  this inline function?


>  extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid,
>  				    int *max_len, struct inode *parent,
>  				    int flags);
> -- 
> 2.31.1
>
Jeffrey Layton Aug. 25, 2023, 6:14 p.m. UTC | #2
On Wed, 2023-08-23 at 17:33 -0400, Alexander Aring wrote:
> This patch reverts mostly commit 40595cdc93ed ("nfs: block notification
> on fs with its own ->lock") and introduces an EXPORT_OP_SAFE_ASYNC_LOCK
> export flag to signal that the "own ->lock" implementation supports
> async lock requests. The only main user is DLM that is used by GFS2 and
> OCFS2 filesystem. Those implement their own lock() implementation and
> return FILE_LOCK_DEFERRED as return value. Since commit 40595cdc93ed
> ("nfs: block notification on fs with its own ->lock") the DLM
> implementation were never updated. This patch should prepare for DLM
> to set the EXPORT_OP_SAFE_ASYNC_LOCK export flag and update the DLM
> plock implementation regarding to it.
> 
> Acked-by: Jeff Layton <jlayton@kernel.org>
> Signed-off-by: Alexander Aring <aahringo@redhat.com>
> ---
>  fs/lockd/svclock.c       |  5 ++---
>  fs/nfsd/nfs4state.c      | 13 ++++++++++---
>  include/linux/exportfs.h |  8 ++++++++
>  3 files changed, 20 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
> index c43ccdf28ed9..6e3b230e8317 100644
> --- a/fs/lockd/svclock.c
> +++ b/fs/lockd/svclock.c
> @@ -470,9 +470,7 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
>  	    struct nlm_host *host, struct nlm_lock *lock, int wait,
>  	    struct nlm_cookie *cookie, int reclaim)
>  {
> -#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
>  	struct inode		*inode = nlmsvc_file_inode(file);
> -#endif
>  	struct nlm_block	*block = NULL;
>  	int			error;
>  	int			mode;
> @@ -486,7 +484,8 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
>  				(long long)lock->fl.fl_end,
>  				wait);
>  
> -	if (nlmsvc_file_file(file)->f_op->lock) {
> +	if (!export_op_support_safe_async_lock(inode->i_sb->s_export_op,
> +					       nlmsvc_file_file(file)->f_op)) {
>  		async_block = wait;
>  		wait = 0;
>  	}
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 3aefbad4cc09..14ca06424ff1 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -7430,6 +7430,7 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>  	struct nfsd4_blocked_lock *nbl = NULL;
>  	struct file_lock *file_lock = NULL;
>  	struct file_lock *conflock = NULL;
> +	struct super_block *sb;
>  	__be32 status = 0;
>  	int lkflg;
>  	int err;
> @@ -7451,6 +7452,7 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>  		dprintk("NFSD: nfsd4_lock: permission denied!\n");
>  		return status;
>  	}
> +	sb = cstate->current_fh.fh_dentry->d_sb;
>  
>  	if (lock->lk_is_new) {
>  		if (nfsd4_has_session(cstate))
> @@ -7502,7 +7504,9 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>  	fp = lock_stp->st_stid.sc_file;
>  	switch (lock->lk_type) {
>  		case NFS4_READW_LT:
> -			if (nfsd4_has_session(cstate))
> +			if (nfsd4_has_session(cstate) ||
> +			    export_op_support_safe_async_lock(sb->s_export_op,
> +							      nf->nf_file->f_op))
>  				fl_flags |= FL_SLEEP;
>  			fallthrough;
>  		case NFS4_READ_LT:
> @@ -7514,7 +7518,9 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>  			fl_type = F_RDLCK;
>  			break;
>  		case NFS4_WRITEW_LT:
> -			if (nfsd4_has_session(cstate))
> +			if (nfsd4_has_session(cstate) ||
> +			    export_op_support_safe_async_lock(sb->s_export_op,
> +							      nf->nf_file->f_op))
>  				fl_flags |= FL_SLEEP;
>  			fallthrough;
>  		case NFS4_WRITE_LT:
> @@ -7542,7 +7548,8 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>  	 * for file locks), so don't attempt blocking lock notifications
>  	 * on those filesystems:
>  	 */
> -	if (nf->nf_file->f_op->lock)
> +	if (!export_op_support_safe_async_lock(sb->s_export_op,
> +					       nf->nf_file->f_op))
>  		fl_flags &= ~FL_SLEEP;
>  
>  	nbl = find_or_allocate_block(lock_sop, &fp->fi_fhandle, nn);
> diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h
> index 11fbd0ee1370..10358a93cdc1 100644
> --- a/include/linux/exportfs.h
> +++ b/include/linux/exportfs.h
> @@ -3,6 +3,7 @@
>  #define LINUX_EXPORTFS_H 1
>  
>  #include <linux/types.h>
> +#include <linux/fs.h>
>  
>  struct dentry;
>  struct iattr;
> @@ -224,9 +225,16 @@ struct export_operations {
>  						  atomic attribute updates
>  						*/
>  #define EXPORT_OP_FLUSH_ON_CLOSE	(0x20) /* fs flushes file data on close */
> +#define EXPORT_OP_SAFE_ASYNC_LOCK	(0x40) /* fs can do async lock request */
>  	unsigned long	flags;
>  };
>  
> +static inline bool export_op_support_safe_async_lock(const struct export_operations *export_ops,
> +						     const struct file_operations *f_op)
> +{
> +	return (export_ops->flags & EXPORT_OP_SAFE_ASYNC_LOCK) || !f_op->lock;
> +}
> +
>  extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid,
>  				    int *max_len, struct inode *parent,
>  				    int flags);

Conceptually, this looks fine, but I agree with Chuck's stylistic
points.
Alexander Aring Aug. 30, 2023, 12:32 p.m. UTC | #3
Hi,

On Fri, Aug 25, 2023 at 1:21 PM Chuck Lever <chuck.lever@oracle.com> wrote:
>
> On Wed, Aug 23, 2023 at 05:33:46PM -0400, Alexander Aring wrote:
> > This patch reverts mostly commit 40595cdc93ed ("nfs: block notification
> > on fs with its own ->lock") and introduces an EXPORT_OP_SAFE_ASYNC_LOCK
> > export flag to signal that the "own ->lock" implementation supports
> > async lock requests. The only main user is DLM that is used by GFS2 and
> > OCFS2 filesystem. Those implement their own lock() implementation and
> > return FILE_LOCK_DEFERRED as return value. Since commit 40595cdc93ed
> > ("nfs: block notification on fs with its own ->lock") the DLM
> > implementation were never updated. This patch should prepare for DLM
> > to set the EXPORT_OP_SAFE_ASYNC_LOCK export flag and update the DLM
> > plock implementation regarding to it.
> >
> > Acked-by: Jeff Layton <jlayton@kernel.org>
> > Signed-off-by: Alexander Aring <aahringo@redhat.com>
> > ---
> >  fs/lockd/svclock.c       |  5 ++---
> >  fs/nfsd/nfs4state.c      | 13 ++++++++++---
> >  include/linux/exportfs.h |  8 ++++++++
> >  3 files changed, 20 insertions(+), 6 deletions(-)
>
> I'm starting to look at these. Just so you know, it's too late for
> inclusion in v6.6, but I think we can get these into shape for v6.7.
>

ok. I base my work on [0], is this correct?

> More below.
>
>
> > diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
> > index c43ccdf28ed9..6e3b230e8317 100644
> > --- a/fs/lockd/svclock.c
> > +++ b/fs/lockd/svclock.c
> > @@ -470,9 +470,7 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
> >           struct nlm_host *host, struct nlm_lock *lock, int wait,
> >           struct nlm_cookie *cookie, int reclaim)
> >  {
> > -#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
> >       struct inode            *inode = nlmsvc_file_inode(file);
> > -#endif
> >       struct nlm_block        *block = NULL;
> >       int                     error;
> >       int                     mode;
> > @@ -486,7 +484,8 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
> >                               (long long)lock->fl.fl_end,
> >                               wait);
> >
> > -     if (nlmsvc_file_file(file)->f_op->lock) {
> > +     if (!export_op_support_safe_async_lock(inode->i_sb->s_export_op,
> > +                                            nlmsvc_file_file(file)->f_op)) {
> >               async_block = wait;
> >               wait = 0;
> >       }
> > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> > index 3aefbad4cc09..14ca06424ff1 100644
> > --- a/fs/nfsd/nfs4state.c
> > +++ b/fs/nfsd/nfs4state.c
> > @@ -7430,6 +7430,7 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> >       struct nfsd4_blocked_lock *nbl = NULL;
> >       struct file_lock *file_lock = NULL;
> >       struct file_lock *conflock = NULL;
> > +     struct super_block *sb;
> >       __be32 status = 0;
> >       int lkflg;
> >       int err;
> > @@ -7451,6 +7452,7 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> >               dprintk("NFSD: nfsd4_lock: permission denied!\n");
> >               return status;
> >       }
> > +     sb = cstate->current_fh.fh_dentry->d_sb;
> >
> >       if (lock->lk_is_new) {
> >               if (nfsd4_has_session(cstate))
> > @@ -7502,7 +7504,9 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> >       fp = lock_stp->st_stid.sc_file;
> >       switch (lock->lk_type) {
> >               case NFS4_READW_LT:
> > -                     if (nfsd4_has_session(cstate))
> > +                     if (nfsd4_has_session(cstate) ||
> > +                         export_op_support_safe_async_lock(sb->s_export_op,
> > +                                                           nf->nf_file->f_op))
> >                               fl_flags |= FL_SLEEP;
> >                       fallthrough;
> >               case NFS4_READ_LT:
> > @@ -7514,7 +7518,9 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> >                       fl_type = F_RDLCK;
> >                       break;
> >               case NFS4_WRITEW_LT:
> > -                     if (nfsd4_has_session(cstate))
> > +                     if (nfsd4_has_session(cstate) ||
> > +                         export_op_support_safe_async_lock(sb->s_export_op,
> > +                                                           nf->nf_file->f_op))
> >                               fl_flags |= FL_SLEEP;
> >                       fallthrough;
> >               case NFS4_WRITE_LT:
> > @@ -7542,7 +7548,8 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> >        * for file locks), so don't attempt blocking lock notifications
> >        * on those filesystems:
> >        */
> > -     if (nf->nf_file->f_op->lock)
> > +     if (!export_op_support_safe_async_lock(sb->s_export_op,
> > +                                            nf->nf_file->f_op))
> >               fl_flags &= ~FL_SLEEP;
> >
> >       nbl = find_or_allocate_block(lock_sop, &fp->fi_fhandle, nn);
> > diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h
> > index 11fbd0ee1370..10358a93cdc1 100644
> > --- a/include/linux/exportfs.h
> > +++ b/include/linux/exportfs.h
> > @@ -3,6 +3,7 @@
> >  #define LINUX_EXPORTFS_H 1
> >
> >  #include <linux/types.h>
> > +#include <linux/fs.h>
> >
> >  struct dentry;
> >  struct iattr;
> > @@ -224,9 +225,16 @@ struct export_operations {
> >                                                 atomic attribute updates
> >                                               */
> >  #define EXPORT_OP_FLUSH_ON_CLOSE     (0x20) /* fs flushes file data on close */
> > +#define EXPORT_OP_SAFE_ASYNC_LOCK    (0x40) /* fs can do async lock request */
>
> We haven't been good about this recently, but the addition of new
> EXPORT_OP flags need to be accompanied by updates to
> Documentation/filesystems/nfs/exporting.rst.
>

ok.

> I will see about adding documentation for other recent flags, but
> please include an update to exporting.rst with this patch.
>

ok.

> I'm not sure we need _SAFE_ in the flag name. Would
> EXPORT_OP_ASYNC_LOCK be OK with you?
>

sure, a vfs_file_lock() can return FILE_LOCK_DEFERRED as well, even
without having this export flag set. How non upstream users use it, I
have no idea as it has some races.

>
> >       unsigned long   flags;
> >  };
> >
> > +static inline bool export_op_support_safe_async_lock(const struct export_operations *export_ops,
> > +                                                  const struct file_operations *f_op)
> > +{
> > +     return (export_ops->flags & EXPORT_OP_SAFE_ASYNC_LOCK) || !f_op->lock;
> > +}
> > +
>
> I'd like some cosmetic changes to this API, since this seems to be
> the first utility function for checking EXPORT_OP flags.
>
> - The function name is unwieldy. How about exportfs_lock_op_is_async() ?
>

ok.

> - Break up the long lines. It's OK with me if the return value type
>   is left on a different line than the function name and parameters.
>

ok.

> - This function is globally visible, so a kdoc comment is needed.
>

ok.

> - The f_op->lock check is common to all the call sites, but it is
>   not at all related to the export AFAICT. Can it be removed from
>   this inline function?
>

This flag implies it makes only sense if the filesystem has its own
lock() implementation, if it doesn't have that I guess the core fs
functions for local file locking are being used.
I guess it can be removed, but it should not be used when there is no
own ->lock() implementation, at least not now until somebody might
update the fs core functionality for local file locking to handle
blocking lock requests asynchronously.

- Alex

[0] https://git.kernel.org/pub/scm/linux/kernel/git/cel/linux.git/log/?h=nfsd-next
Chuck Lever III Aug. 30, 2023, 1:45 p.m. UTC | #4
On Wed, Aug 30, 2023 at 08:32:43AM -0400, Alexander Aring wrote:
> Hi,
> 
> On Fri, Aug 25, 2023 at 1:21 PM Chuck Lever <chuck.lever@oracle.com> wrote:
> >
> > On Wed, Aug 23, 2023 at 05:33:46PM -0400, Alexander Aring wrote:
> > > This patch reverts mostly commit 40595cdc93ed ("nfs: block notification
> > > on fs with its own ->lock") and introduces an EXPORT_OP_SAFE_ASYNC_LOCK
> > > export flag to signal that the "own ->lock" implementation supports
> > > async lock requests. The only main user is DLM that is used by GFS2 and
> > > OCFS2 filesystem. Those implement their own lock() implementation and
> > > return FILE_LOCK_DEFERRED as return value. Since commit 40595cdc93ed
> > > ("nfs: block notification on fs with its own ->lock") the DLM
> > > implementation were never updated. This patch should prepare for DLM
> > > to set the EXPORT_OP_SAFE_ASYNC_LOCK export flag and update the DLM
> > > plock implementation regarding to it.
> > >
> > > Acked-by: Jeff Layton <jlayton@kernel.org>
> > > Signed-off-by: Alexander Aring <aahringo@redhat.com>
> > > ---
> > >  fs/lockd/svclock.c       |  5 ++---
> > >  fs/nfsd/nfs4state.c      | 13 ++++++++++---
> > >  include/linux/exportfs.h |  8 ++++++++
> > >  3 files changed, 20 insertions(+), 6 deletions(-)
> >
> > I'm starting to look at these. Just so you know, it's too late for
> > inclusion in v6.6, but I think we can get these into shape for v6.7.
> >
> 
> ok. I base my work on [0], is this correct?

Correct.

Fyi, that is currently what is pending for v6.6. When the merge
window closes, it will jump to what will go into v6.7.


> > - The f_op->lock check is common to all the call sites, but it is
> >   not at all related to the export AFAICT. Can it be removed from
> >   this inline function?
> >
> 
> This flag implies it makes only sense if the filesystem has its own
> lock() implementation, if it doesn't have that I guess the core fs
> functions for local file locking are being used.
> I guess it can be removed, but it should not be used when there is no
> own ->lock() implementation, at least not now until somebody might
> update the fs core functionality for local file locking to handle
> blocking lock requests asynchronously.

Can that be handled with a remark in the documenting comment?


> [0] https://git.kernel.org/pub/scm/linux/kernel/git/cel/linux.git/log/?h=nfsd-next
diff mbox series

Patch

diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
index c43ccdf28ed9..6e3b230e8317 100644
--- a/fs/lockd/svclock.c
+++ b/fs/lockd/svclock.c
@@ -470,9 +470,7 @@  nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
 	    struct nlm_host *host, struct nlm_lock *lock, int wait,
 	    struct nlm_cookie *cookie, int reclaim)
 {
-#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
 	struct inode		*inode = nlmsvc_file_inode(file);
-#endif
 	struct nlm_block	*block = NULL;
 	int			error;
 	int			mode;
@@ -486,7 +484,8 @@  nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
 				(long long)lock->fl.fl_end,
 				wait);
 
-	if (nlmsvc_file_file(file)->f_op->lock) {
+	if (!export_op_support_safe_async_lock(inode->i_sb->s_export_op,
+					       nlmsvc_file_file(file)->f_op)) {
 		async_block = wait;
 		wait = 0;
 	}
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 3aefbad4cc09..14ca06424ff1 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -7430,6 +7430,7 @@  nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	struct nfsd4_blocked_lock *nbl = NULL;
 	struct file_lock *file_lock = NULL;
 	struct file_lock *conflock = NULL;
+	struct super_block *sb;
 	__be32 status = 0;
 	int lkflg;
 	int err;
@@ -7451,6 +7452,7 @@  nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 		dprintk("NFSD: nfsd4_lock: permission denied!\n");
 		return status;
 	}
+	sb = cstate->current_fh.fh_dentry->d_sb;
 
 	if (lock->lk_is_new) {
 		if (nfsd4_has_session(cstate))
@@ -7502,7 +7504,9 @@  nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	fp = lock_stp->st_stid.sc_file;
 	switch (lock->lk_type) {
 		case NFS4_READW_LT:
-			if (nfsd4_has_session(cstate))
+			if (nfsd4_has_session(cstate) ||
+			    export_op_support_safe_async_lock(sb->s_export_op,
+							      nf->nf_file->f_op))
 				fl_flags |= FL_SLEEP;
 			fallthrough;
 		case NFS4_READ_LT:
@@ -7514,7 +7518,9 @@  nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 			fl_type = F_RDLCK;
 			break;
 		case NFS4_WRITEW_LT:
-			if (nfsd4_has_session(cstate))
+			if (nfsd4_has_session(cstate) ||
+			    export_op_support_safe_async_lock(sb->s_export_op,
+							      nf->nf_file->f_op))
 				fl_flags |= FL_SLEEP;
 			fallthrough;
 		case NFS4_WRITE_LT:
@@ -7542,7 +7548,8 @@  nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	 * for file locks), so don't attempt blocking lock notifications
 	 * on those filesystems:
 	 */
-	if (nf->nf_file->f_op->lock)
+	if (!export_op_support_safe_async_lock(sb->s_export_op,
+					       nf->nf_file->f_op))
 		fl_flags &= ~FL_SLEEP;
 
 	nbl = find_or_allocate_block(lock_sop, &fp->fi_fhandle, nn);
diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h
index 11fbd0ee1370..10358a93cdc1 100644
--- a/include/linux/exportfs.h
+++ b/include/linux/exportfs.h
@@ -3,6 +3,7 @@ 
 #define LINUX_EXPORTFS_H 1
 
 #include <linux/types.h>
+#include <linux/fs.h>
 
 struct dentry;
 struct iattr;
@@ -224,9 +225,16 @@  struct export_operations {
 						  atomic attribute updates
 						*/
 #define EXPORT_OP_FLUSH_ON_CLOSE	(0x20) /* fs flushes file data on close */
+#define EXPORT_OP_SAFE_ASYNC_LOCK	(0x40) /* fs can do async lock request */
 	unsigned long	flags;
 };
 
+static inline bool export_op_support_safe_async_lock(const struct export_operations *export_ops,
+						     const struct file_operations *f_op)
+{
+	return (export_ops->flags & EXPORT_OP_SAFE_ASYNC_LOCK) || !f_op->lock;
+}
+
 extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid,
 				    int *max_len, struct inode *parent,
 				    int flags);