[7/7] NFS: Add a mount option for READ_PLUS
diff mbox series

Message ID 20200110223455.528471-8-Anna.Schumaker@Netapp.com
State New
Headers show
Series
  • NFS: Add support for the v4.2 READ_PLUS operation
Related show

Commit Message

Anna Schumaker Jan. 10, 2020, 10:34 p.m. UTC
From: Anna Schumaker <Anna.Schumaker@Netapp.com>

There are some workloads where READ_PLUS might end up hurting
performance, so let's be nice to users and provide a way to disable this
operation similar to how READDIR_PLUS can be disabled.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
---
 fs/nfs/fs_context.c       | 14 ++++++++++++++
 fs/nfs/nfs4client.c       |  3 +++
 include/linux/nfs_fs_sb.h |  1 +
 3 files changed, 18 insertions(+)

Comments

Chuck Lever Jan. 10, 2020, 10:41 p.m. UTC | #1
Hi Anna-

> On Jan 10, 2020, at 5:34 PM, schumaker.anna@gmail.com wrote:
> 
> From: Anna Schumaker <Anna.Schumaker@Netapp.com>
> 
> There are some workloads where READ_PLUS might end up hurting
> performance,

Can you say more about this? Have you seen workloads that are
hurt by READ_PLUS? Nothing jumps out at me from the tables in
the cover letter.


> so let's be nice to users and provide a way to disable this
> operation similar to how READDIR_PLUS can be disabled.

Does it make sense to hold off on a mount option until there
is evidence that there is no other way to work around such a
performance regression?

- Attempt to address the regression directly
- Improve the heuristics about when READ_PLUS is used
- Document that dropping back to vers=4.1 will disable it

Any experience with NFS/RDMA?


> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
> ---
> fs/nfs/fs_context.c       | 14 ++++++++++++++
> fs/nfs/nfs4client.c       |  3 +++
> include/linux/nfs_fs_sb.h |  1 +
> 3 files changed, 18 insertions(+)
> 
> diff --git a/fs/nfs/fs_context.c b/fs/nfs/fs_context.c
> index 0247dcb7b316..82ba07c7c1ce 100644
> --- a/fs/nfs/fs_context.c
> +++ b/fs/nfs/fs_context.c
> @@ -64,6 +64,7 @@ enum nfs_param {
> 	Opt_proto,
> 	Opt_rdirplus,
> 	Opt_rdma,
> +	Opt_readplus,
> 	Opt_resvport,
> 	Opt_retrans,
> 	Opt_retry,
> @@ -120,6 +121,7 @@ static const struct fs_parameter_spec nfs_param_specs[] = {
> 	fsparam_string("proto",		Opt_proto),
> 	fsparam_flag_no("rdirplus",	Opt_rdirplus),
> 	fsparam_flag  ("rdma",		Opt_rdma),
> +	fsparam_flag_no("readplus",	Opt_readplus),
> 	fsparam_flag_no("resvport",	Opt_resvport),
> 	fsparam_u32   ("retrans",	Opt_retrans),
> 	fsparam_string("retry",		Opt_retry),
> @@ -555,6 +557,12 @@ static int nfs_fs_context_parse_param(struct fs_context *fc,
> 		else
> 			ctx->options |= NFS_OPTION_MIGRATION;
> 		break;
> +	case Opt_readplus:
> +		if (result.negated)
> +			ctx->options |= NFS_OPTION_NO_READ_PLUS;
> +		else
> +			ctx->options &= ~NFS_OPTION_NO_READ_PLUS;
> +		break;
> 
> 		/*
> 		 * options that take numeric values
> @@ -1176,6 +1184,10 @@ static int nfs_fs_context_validate(struct fs_context *fc)
> 	    (ctx->version != 4 || ctx->minorversion != 0))
> 		goto out_migration_misuse;
> 
> +	if (ctx->options & NFS_OPTION_NO_READ_PLUS &&
> +	    (ctx->version != 4 || ctx->minorversion < 2))
> +		goto out_noreadplus_misuse;
> +
> 	/* Verify that any proto=/mountproto= options match the address
> 	 * families in the addr=/mountaddr= options.
> 	 */
> @@ -1254,6 +1266,8 @@ static int nfs_fs_context_validate(struct fs_context *fc)
> 			  ctx->version, ctx->minorversion);
> out_migration_misuse:
> 	return nfs_invalf(fc, "NFS: 'Migration' not supported for this NFS version");
> +out_noreadplus_misuse:
> +	return nfs_invalf(fc, "NFS: 'noreadplus' not supported for this NFS version\n");
> out_version_unavailable:
> 	nfs_errorf(fc, "NFS: Version unavailable");
> 	return ret;
> diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c
> index 0cd767e5c977..868dc3c36ba1 100644
> --- a/fs/nfs/nfs4client.c
> +++ b/fs/nfs/nfs4client.c
> @@ -1016,6 +1016,9 @@ static int nfs4_server_common_setup(struct nfs_server *server,
> 	server->caps |= server->nfs_client->cl_mvops->init_caps;
> 	if (server->flags & NFS_MOUNT_NORDIRPLUS)
> 			server->caps &= ~NFS_CAP_READDIRPLUS;
> +	if (server->options & NFS_OPTION_NO_READ_PLUS)
> +		server->caps &= ~NFS_CAP_READ_PLUS;
> +
> 	/*
> 	 * Don't use NFS uid/gid mapping if we're using AUTH_SYS or lower
> 	 * authentication.
> diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
> index 11248c5a7b24..360e70c7bbb6 100644
> --- a/include/linux/nfs_fs_sb.h
> +++ b/include/linux/nfs_fs_sb.h
> @@ -172,6 +172,7 @@ struct nfs_server {
> 	unsigned int		clone_blksize;	/* granularity of a CLONE operation */
> #define NFS_OPTION_FSCACHE	0x00000001	/* - local caching enabled */
> #define NFS_OPTION_MIGRATION	0x00000002	/* - NFSv4 migration enabled */
> +#define NFS_OPTION_NO_READ_PLUS	0x00000004	/* - NFSv4.2 READ_PLUS enabled */
> 
> 	struct nfs_fsid		fsid;
> 	__u64			maxfilesize;	/* maximum file size */
> -- 
> 2.24.1
> 

--
Chuck Lever
Anna Schumaker Jan. 10, 2020, 10:43 p.m. UTC | #2
Hi Chuck,

On Fri, 2020-01-10 at 17:41 -0500, Chuck Lever wrote:
> NetApp Security WARNING: This is an external email. Do not click links or open
> attachments unless you recognize the sender and know the content is safe.
> 
> 
> 
> 
> Hi Anna-
> 
> > On Jan 10, 2020, at 5:34 PM, schumaker.anna@gmail.com wrote:
> > 
> > From: Anna Schumaker <Anna.Schumaker@Netapp.com>
> > 
> > There are some workloads where READ_PLUS might end up hurting
> > performance,
> 
> Can you say more about this? Have you seen workloads that are
> hurt by READ_PLUS? Nothing jumps out at me from the tables in
> the cover letter.

It's mostly something I've seen when using btrfs in a virtual machine (so
probably not a wide use case, and it's possible I need to change something in my
setup to get it working better).

> 
> 
> > so let's be nice to users and provide a way to disable this
> > operation similar to how READDIR_PLUS can be disabled.
> 
> Does it make sense to hold off on a mount option until there
> is evidence that there is no other way to work around such a
> performance regression?
> 
> - Attempt to address the regression directly
> - Improve the heuristics about when READ_PLUS is used
> - Document that dropping back to vers=4.1 will disable it

Yeah, we could hold off on the patch for now and see if anybody has any issues
first.

> 
> Any experience with NFS/RDMA?

Not yet, but I can try to test that next week.

Anna

> 
> 
> > Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
> > ---
> > fs/nfs/fs_context.c       | 14 ++++++++++++++
> > fs/nfs/nfs4client.c       |  3 +++
> > include/linux/nfs_fs_sb.h |  1 +
> > 3 files changed, 18 insertions(+)
> > 
> > diff --git a/fs/nfs/fs_context.c b/fs/nfs/fs_context.c
> > index 0247dcb7b316..82ba07c7c1ce 100644
> > --- a/fs/nfs/fs_context.c
> > +++ b/fs/nfs/fs_context.c
> > @@ -64,6 +64,7 @@ enum nfs_param {
> >       Opt_proto,
> >       Opt_rdirplus,
> >       Opt_rdma,
> > +     Opt_readplus,
> >       Opt_resvport,
> >       Opt_retrans,
> >       Opt_retry,
> > @@ -120,6 +121,7 @@ static const struct fs_parameter_spec nfs_param_specs[]
> > = {
> >       fsparam_string("proto",         Opt_proto),
> >       fsparam_flag_no("rdirplus",     Opt_rdirplus),
> >       fsparam_flag  ("rdma",          Opt_rdma),
> > +     fsparam_flag_no("readplus",     Opt_readplus),
> >       fsparam_flag_no("resvport",     Opt_resvport),
> >       fsparam_u32   ("retrans",       Opt_retrans),
> >       fsparam_string("retry",         Opt_retry),
> > @@ -555,6 +557,12 @@ static int nfs_fs_context_parse_param(struct fs_context
> > *fc,
> >               else
> >                       ctx->options |= NFS_OPTION_MIGRATION;
> >               break;
> > +     case Opt_readplus:
> > +             if (result.negated)
> > +                     ctx->options |= NFS_OPTION_NO_READ_PLUS;
> > +             else
> > +                     ctx->options &= ~NFS_OPTION_NO_READ_PLUS;
> > +             break;
> > 
> >               /*
> >                * options that take numeric values
> > @@ -1176,6 +1184,10 @@ static int nfs_fs_context_validate(struct fs_context
> > *fc)
> >           (ctx->version != 4 || ctx->minorversion != 0))
> >               goto out_migration_misuse;
> > 
> > +     if (ctx->options & NFS_OPTION_NO_READ_PLUS &&
> > +         (ctx->version != 4 || ctx->minorversion < 2))
> > +             goto out_noreadplus_misuse;
> > +
> >       /* Verify that any proto=/mountproto= options match the address
> >        * families in the addr=/mountaddr= options.
> >        */
> > @@ -1254,6 +1266,8 @@ static int nfs_fs_context_validate(struct fs_context
> > *fc)
> >                         ctx->version, ctx->minorversion);
> > out_migration_misuse:
> >       return nfs_invalf(fc, "NFS: 'Migration' not supported for this NFS
> > version");
> > +out_noreadplus_misuse:
> > +     return nfs_invalf(fc, "NFS: 'noreadplus' not supported for this NFS
> > version\n");
> > out_version_unavailable:
> >       nfs_errorf(fc, "NFS: Version unavailable");
> >       return ret;
> > diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c
> > index 0cd767e5c977..868dc3c36ba1 100644
> > --- a/fs/nfs/nfs4client.c
> > +++ b/fs/nfs/nfs4client.c
> > @@ -1016,6 +1016,9 @@ static int nfs4_server_common_setup(struct nfs_server
> > *server,
> >       server->caps |= server->nfs_client->cl_mvops->init_caps;
> >       if (server->flags & NFS_MOUNT_NORDIRPLUS)
> >                       server->caps &= ~NFS_CAP_READDIRPLUS;
> > +     if (server->options & NFS_OPTION_NO_READ_PLUS)
> > +             server->caps &= ~NFS_CAP_READ_PLUS;
> > +
> >       /*
> >        * Don't use NFS uid/gid mapping if we're using AUTH_SYS or lower
> >        * authentication.
> > diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
> > index 11248c5a7b24..360e70c7bbb6 100644
> > --- a/include/linux/nfs_fs_sb.h
> > +++ b/include/linux/nfs_fs_sb.h
> > @@ -172,6 +172,7 @@ struct nfs_server {
> >       unsigned int            clone_blksize;  /* granularity of a CLONE
> > operation */
> > #define NFS_OPTION_FSCACHE    0x00000001      /* - local caching enabled */
> > #define NFS_OPTION_MIGRATION  0x00000002      /* - NFSv4 migration enabled
> > */
> > +#define NFS_OPTION_NO_READ_PLUS      0x00000004      /* - NFSv4.2 READ_PLUS
> > enabled */
> > 
> >       struct nfs_fsid         fsid;
> >       __u64                   maxfilesize;    /* maximum file size */
> > --
> > 2.24.1
> > 
> 
> --
> Chuck Lever
> 
> 
>
Chuck Lever Jan. 10, 2020, 10:45 p.m. UTC | #3
> On Jan 10, 2020, at 5:43 PM, Schumaker, Anna <Anna.Schumaker@netapp.com> wrote:
> 
> Hi Chuck,
> 
> On Fri, 2020-01-10 at 17:41 -0500, Chuck Lever wrote:
>> NetApp Security WARNING: This is an external email. Do not click links or open
>> attachments unless you recognize the sender and know the content is safe.
>> 
>> 
>> 
>> 
>> Hi Anna-
>> 
>>> On Jan 10, 2020, at 5:34 PM, schumaker.anna@gmail.com wrote:
>>> 
>>> From: Anna Schumaker <Anna.Schumaker@Netapp.com>
>>> 
>>> There are some workloads where READ_PLUS might end up hurting
>>> performance,
>> 
>> Can you say more about this? Have you seen workloads that are
>> hurt by READ_PLUS? Nothing jumps out at me from the tables in
>> the cover letter.
> 
> It's mostly something I've seen when using btrfs in a virtual machine (so
> probably not a wide use case, and it's possible I need to change something in my
> setup to get it working better).
> 
>> 
>> 
>>> so let's be nice to users and provide a way to disable this
>>> operation similar to how READDIR_PLUS can be disabled.
>> 
>> Does it make sense to hold off on a mount option until there
>> is evidence that there is no other way to work around such a
>> performance regression?
>> 
>> - Attempt to address the regression directly
>> - Improve the heuristics about when READ_PLUS is used
>> - Document that dropping back to vers=4.1 will disable it
> 
> Yeah, we could hold off on the patch for now and see if anybody has any issues
> first.
> 
>> 
>> Any experience with NFS/RDMA?
> 
> Not yet, but I can try to test that next week.

Thanks for your response!


> Anna
> 
>> 
>> 
>>> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
>>> ---
>>> fs/nfs/fs_context.c       | 14 ++++++++++++++
>>> fs/nfs/nfs4client.c       |  3 +++
>>> include/linux/nfs_fs_sb.h |  1 +
>>> 3 files changed, 18 insertions(+)
>>> 
>>> diff --git a/fs/nfs/fs_context.c b/fs/nfs/fs_context.c
>>> index 0247dcb7b316..82ba07c7c1ce 100644
>>> --- a/fs/nfs/fs_context.c
>>> +++ b/fs/nfs/fs_context.c
>>> @@ -64,6 +64,7 @@ enum nfs_param {
>>>      Opt_proto,
>>>      Opt_rdirplus,
>>>      Opt_rdma,
>>> +     Opt_readplus,
>>>      Opt_resvport,
>>>      Opt_retrans,
>>>      Opt_retry,
>>> @@ -120,6 +121,7 @@ static const struct fs_parameter_spec nfs_param_specs[]
>>> = {
>>>      fsparam_string("proto",         Opt_proto),
>>>      fsparam_flag_no("rdirplus",     Opt_rdirplus),
>>>      fsparam_flag  ("rdma",          Opt_rdma),
>>> +     fsparam_flag_no("readplus",     Opt_readplus),
>>>      fsparam_flag_no("resvport",     Opt_resvport),
>>>      fsparam_u32   ("retrans",       Opt_retrans),
>>>      fsparam_string("retry",         Opt_retry),
>>> @@ -555,6 +557,12 @@ static int nfs_fs_context_parse_param(struct fs_context
>>> *fc,
>>>              else
>>>                      ctx->options |= NFS_OPTION_MIGRATION;
>>>              break;
>>> +     case Opt_readplus:
>>> +             if (result.negated)
>>> +                     ctx->options |= NFS_OPTION_NO_READ_PLUS;
>>> +             else
>>> +                     ctx->options &= ~NFS_OPTION_NO_READ_PLUS;
>>> +             break;
>>> 
>>>              /*
>>>               * options that take numeric values
>>> @@ -1176,6 +1184,10 @@ static int nfs_fs_context_validate(struct fs_context
>>> *fc)
>>>          (ctx->version != 4 || ctx->minorversion != 0))
>>>              goto out_migration_misuse;
>>> 
>>> +     if (ctx->options & NFS_OPTION_NO_READ_PLUS &&
>>> +         (ctx->version != 4 || ctx->minorversion < 2))
>>> +             goto out_noreadplus_misuse;
>>> +
>>>      /* Verify that any proto=/mountproto= options match the address
>>>       * families in the addr=/mountaddr= options.
>>>       */
>>> @@ -1254,6 +1266,8 @@ static int nfs_fs_context_validate(struct fs_context
>>> *fc)
>>>                        ctx->version, ctx->minorversion);
>>> out_migration_misuse:
>>>      return nfs_invalf(fc, "NFS: 'Migration' not supported for this NFS
>>> version");
>>> +out_noreadplus_misuse:
>>> +     return nfs_invalf(fc, "NFS: 'noreadplus' not supported for this NFS
>>> version\n");
>>> out_version_unavailable:
>>>      nfs_errorf(fc, "NFS: Version unavailable");
>>>      return ret;
>>> diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c
>>> index 0cd767e5c977..868dc3c36ba1 100644
>>> --- a/fs/nfs/nfs4client.c
>>> +++ b/fs/nfs/nfs4client.c
>>> @@ -1016,6 +1016,9 @@ static int nfs4_server_common_setup(struct nfs_server
>>> *server,
>>>      server->caps |= server->nfs_client->cl_mvops->init_caps;
>>>      if (server->flags & NFS_MOUNT_NORDIRPLUS)
>>>                      server->caps &= ~NFS_CAP_READDIRPLUS;
>>> +     if (server->options & NFS_OPTION_NO_READ_PLUS)
>>> +             server->caps &= ~NFS_CAP_READ_PLUS;
>>> +
>>>      /*
>>>       * Don't use NFS uid/gid mapping if we're using AUTH_SYS or lower
>>>       * authentication.
>>> diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
>>> index 11248c5a7b24..360e70c7bbb6 100644
>>> --- a/include/linux/nfs_fs_sb.h
>>> +++ b/include/linux/nfs_fs_sb.h
>>> @@ -172,6 +172,7 @@ struct nfs_server {
>>>      unsigned int            clone_blksize;  /* granularity of a CLONE
>>> operation */
>>> #define NFS_OPTION_FSCACHE    0x00000001      /* - local caching enabled */
>>> #define NFS_OPTION_MIGRATION  0x00000002      /* - NFSv4 migration enabled
>>> */
>>> +#define NFS_OPTION_NO_READ_PLUS      0x00000004      /* - NFSv4.2 READ_PLUS
>>> enabled */
>>> 
>>>      struct nfs_fsid         fsid;
>>>      __u64                   maxfilesize;    /* maximum file size */
>>> --
>>> 2.24.1
>>> 
>> 
>> --
>> Chuck Lever
>> 
>> 
>> 

--
Chuck Lever

Patch
diff mbox series

diff --git a/fs/nfs/fs_context.c b/fs/nfs/fs_context.c
index 0247dcb7b316..82ba07c7c1ce 100644
--- a/fs/nfs/fs_context.c
+++ b/fs/nfs/fs_context.c
@@ -64,6 +64,7 @@  enum nfs_param {
 	Opt_proto,
 	Opt_rdirplus,
 	Opt_rdma,
+	Opt_readplus,
 	Opt_resvport,
 	Opt_retrans,
 	Opt_retry,
@@ -120,6 +121,7 @@  static const struct fs_parameter_spec nfs_param_specs[] = {
 	fsparam_string("proto",		Opt_proto),
 	fsparam_flag_no("rdirplus",	Opt_rdirplus),
 	fsparam_flag  ("rdma",		Opt_rdma),
+	fsparam_flag_no("readplus",	Opt_readplus),
 	fsparam_flag_no("resvport",	Opt_resvport),
 	fsparam_u32   ("retrans",	Opt_retrans),
 	fsparam_string("retry",		Opt_retry),
@@ -555,6 +557,12 @@  static int nfs_fs_context_parse_param(struct fs_context *fc,
 		else
 			ctx->options |= NFS_OPTION_MIGRATION;
 		break;
+	case Opt_readplus:
+		if (result.negated)
+			ctx->options |= NFS_OPTION_NO_READ_PLUS;
+		else
+			ctx->options &= ~NFS_OPTION_NO_READ_PLUS;
+		break;
 
 		/*
 		 * options that take numeric values
@@ -1176,6 +1184,10 @@  static int nfs_fs_context_validate(struct fs_context *fc)
 	    (ctx->version != 4 || ctx->minorversion != 0))
 		goto out_migration_misuse;
 
+	if (ctx->options & NFS_OPTION_NO_READ_PLUS &&
+	    (ctx->version != 4 || ctx->minorversion < 2))
+		goto out_noreadplus_misuse;
+
 	/* Verify that any proto=/mountproto= options match the address
 	 * families in the addr=/mountaddr= options.
 	 */
@@ -1254,6 +1266,8 @@  static int nfs_fs_context_validate(struct fs_context *fc)
 			  ctx->version, ctx->minorversion);
 out_migration_misuse:
 	return nfs_invalf(fc, "NFS: 'Migration' not supported for this NFS version");
+out_noreadplus_misuse:
+	return nfs_invalf(fc, "NFS: 'noreadplus' not supported for this NFS version\n");
 out_version_unavailable:
 	nfs_errorf(fc, "NFS: Version unavailable");
 	return ret;
diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c
index 0cd767e5c977..868dc3c36ba1 100644
--- a/fs/nfs/nfs4client.c
+++ b/fs/nfs/nfs4client.c
@@ -1016,6 +1016,9 @@  static int nfs4_server_common_setup(struct nfs_server *server,
 	server->caps |= server->nfs_client->cl_mvops->init_caps;
 	if (server->flags & NFS_MOUNT_NORDIRPLUS)
 			server->caps &= ~NFS_CAP_READDIRPLUS;
+	if (server->options & NFS_OPTION_NO_READ_PLUS)
+		server->caps &= ~NFS_CAP_READ_PLUS;
+
 	/*
 	 * Don't use NFS uid/gid mapping if we're using AUTH_SYS or lower
 	 * authentication.
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index 11248c5a7b24..360e70c7bbb6 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -172,6 +172,7 @@  struct nfs_server {
 	unsigned int		clone_blksize;	/* granularity of a CLONE operation */
 #define NFS_OPTION_FSCACHE	0x00000001	/* - local caching enabled */
 #define NFS_OPTION_MIGRATION	0x00000002	/* - NFSv4 migration enabled */
+#define NFS_OPTION_NO_READ_PLUS	0x00000004	/* - NFSv4.2 READ_PLUS enabled */
 
 	struct nfs_fsid		fsid;
 	__u64			maxfilesize;	/* maximum file size */