Re: [PATCH v2 06/12] nfsd: add tracepoints around nfsd_create events

[Jeff Layton]

On Wed, 2025-04-09 at 11:09 -0400, Chuck Lever wrote:
> On 4/9/25 10:32 AM, Jeff Layton wrote:
> > ...and remove the legacy dprintks.
> > 
> > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> > ---
> >  fs/nfsd/nfs3proc.c | 18 +++++-------------
> >  fs/nfsd/nfs4proc.c | 29 +++++++++++++++++++++++++++++
> >  fs/nfsd/nfsproc.c  |  6 +++---
> >  fs/nfsd/trace.h    | 39 +++++++++++++++++++++++++++++++++++++++
> >  4 files changed, 76 insertions(+), 16 deletions(-)
> > 
> > diff --git a/fs/nfsd/nfs3proc.c b/fs/nfsd/nfs3proc.c
> > index 372bdcf5e07a5c835da240ecebb02e3576eb2ca6..ea1280970ea11b2a82f0de88ad0422eef7063d6d 100644
> > --- a/fs/nfsd/nfs3proc.c
> > +++ b/fs/nfsd/nfs3proc.c
> > @@ -14,6 +14,7 @@
> >  #include "xdr3.h"
> >  #include "vfs.h"
> >  #include "filecache.h"
> > +#include "trace.h"
> >  
> >  #define NFSDDBG_FACILITY		NFSDDBG_PROC
> >  
> > @@ -380,10 +381,7 @@ nfsd3_proc_create(struct svc_rqst *rqstp)
> >  	struct nfsd3_diropres *resp = rqstp->rq_resp;
> >  	svc_fh *dirfhp, *newfhp;
> >  
> > -	dprintk("nfsd: CREATE(3)   %s %.*s\n",
> > -				SVCFH_fmt(&argp->fh),
> > -				argp->len,
> > -				argp->name);
> > +	trace_nfsd3_proc_create(rqstp, &argp->fh, S_IFREG, argp->name, argp->len);
> >  
> >  	dirfhp = fh_copy(&resp->dirfh, &argp->fh);
> >  	newfhp = fh_init(&resp->fh, NFS3_FHSIZE);
> > @@ -405,10 +403,7 @@ nfsd3_proc_mkdir(struct svc_rqst *rqstp)
> >  		.na_iattr	= &argp->attrs,
> >  	};
> >  
> > -	dprintk("nfsd: MKDIR(3)    %s %.*s\n",
> > -				SVCFH_fmt(&argp->fh),
> > -				argp->len,
> > -				argp->name);
> > +	trace_nfsd3_proc_mkdir(rqstp, &argp->fh, S_IFDIR, argp->name, argp->len);
> >  
> >  	argp->attrs.ia_valid &= ~ATTR_SIZE;
> >  	fh_copy(&resp->dirfh, &argp->fh);
> > @@ -471,13 +466,10 @@ nfsd3_proc_mknod(struct svc_rqst *rqstp)
> >  	struct nfsd_attrs attrs = {
> >  		.na_iattr	= &argp->attrs,
> >  	};
> > -	int type;
> > +	int type = nfs3_ftypes[argp->ftype];
> >  	dev_t	rdev = 0;
> >  
> > -	dprintk("nfsd: MKNOD(3)    %s %.*s\n",
> > -				SVCFH_fmt(&argp->fh),
> > -				argp->len,
> > -				argp->name);
> > +	trace_nfsd3_proc_mknod(rqstp, &argp->fh, type, argp->name, argp->len);
> >  
> >  	fh_copy(&resp->dirfh, &argp->fh);
> >  	fh_init(&resp->fh, NFS3_FHSIZE);
> > diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> > index 6e23d6103010197c0316b07c189fe12ec3033812..2c795103deaa4044596bd07d90db788169a32a0c 100644
> > --- a/fs/nfsd/nfs4proc.c
> > +++ b/fs/nfsd/nfs4proc.c
> > @@ -250,6 +250,8 @@ nfsd4_create_file(struct svc_rqst *rqstp, struct svc_fh *fhp,
> >  	__be32 status;
> >  	int host_err;
> >  
> > +	trace_nfsd4_create_file(rqstp, fhp, S_IFREG, open->op_fname, open->op_fnamelen);
> > +
> >  	if (isdotent(open->op_fname, open->op_fnamelen))
> >  		return nfserr_exist;
> >  	if (!(iap->ia_valid & ATTR_MODE))
> > @@ -807,6 +809,29 @@ nfsd4_commit(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> >  	return status;
> >  }
> >  
> > +static umode_t nfs_type_to_vfs_type(enum nfs_ftype4 nfstype)
> > +{
> > +	switch (nfstype) {
> > +	case NF4REG:
> > +		return S_IFREG;
> > +	case NF4DIR:
> > +		return S_IFDIR;
> > +	case NF4BLK:
> > +		return S_IFBLK;
> > +	case NF4CHR:
> > +		return S_IFCHR;
> > +	case NF4LNK:
> > +		return S_IFLNK;
> > +	case NF4SOCK:
> > +		return S_IFSOCK;
> > +	case NF4FIFO:
> > +		return S_IFIFO;
> > +	default:
> > +		break;
> > +	}
> > +	return 0;
> > +}
> > +
> 
> Wondering what happens when trace points are disabled in the kernel
> build. Maybe this helper belongs in fs/nfsd/trace.h instead as a
> macro wrapper for __print_symbolic(). But see below.
> 

If tracepoints are disabled, then the only caller of this static
function would go away, so it should get optimized out. I don't see how
you'd make this a wrapper around __print_symbolic(), since the point is
to pass in a NFS version-independent constant that the tracepoint class
can use as a type.

> 
> >  static __be32
> >  nfsd4_create(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> >  	     union nfsd4_op_u *u)
> > @@ -822,6 +847,10 @@ nfsd4_create(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> >  	__be32 status;
> >  	dev_t rdev;
> >  
> > +	trace_nfsd4_create(rqstp, &cstate->current_fh,
> > +			   nfs_type_to_vfs_type(create->cr_type),
> > +			   create->cr_name, create->cr_namelen);
> > +
> >  	fh_init(&resfh, NFS4_FHSIZE);
> >  
> >  	status = fh_verify(rqstp, &cstate->current_fh, S_IFDIR, NFSD_MAY_NOP);
> > diff --git a/fs/nfsd/nfsproc.c b/fs/nfsd/nfsproc.c
> > index 6dda081eb24c00b834ab0965c3a35a12115bceb7..33d8cbf8785588d38d4ec5efd769c1d1d06c6a91 100644
> > --- a/fs/nfsd/nfsproc.c
> > +++ b/fs/nfsd/nfsproc.c
> > @@ -10,6 +10,7 @@
> >  #include "cache.h"
> >  #include "xdr.h"
> >  #include "vfs.h"
> > +#include "trace.h"
> >  
> >  #define NFSDDBG_FACILITY		NFSDDBG_PROC
> >  
> > @@ -292,8 +293,7 @@ nfsd_proc_create(struct svc_rqst *rqstp)
> >  	int		hosterr;
> >  	dev_t		rdev = 0, wanted = new_decode_dev(attr->ia_size);
> >  
> > -	dprintk("nfsd: CREATE   %s %.*s\n",
> > -		SVCFH_fmt(dirfhp), argp->len, argp->name);
> > +	trace_nfsd_proc_create(rqstp, dirfhp, S_IFREG, argp->name, argp->len);
> >  
> >  	/* First verify the parent file handle */
> >  	resp->status = fh_verify(rqstp, dirfhp, S_IFDIR, NFSD_MAY_EXEC);
> > @@ -548,7 +548,7 @@ nfsd_proc_mkdir(struct svc_rqst *rqstp)
> >  		.na_iattr	= &argp->attrs,
> >  	};
> >  
> > -	dprintk("nfsd: MKDIR    %s %.*s\n", SVCFH_fmt(&argp->fh), argp->len, argp->name);
> > +	trace_nfsd_proc_mkdir(rqstp, &argp->fh, S_IFDIR, argp->name, argp->len);
> >  
> >  	if (resp->fh.fh_dentry) {
> >  		printk(KERN_WARNING
> > diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h
> > index 382849d7c321d6ded8213890c2e7075770aa716c..c6aff23a845f06c87e701d57ec577c2c5c5a743c 100644
> > --- a/fs/nfsd/trace.h
> > +++ b/fs/nfsd/trace.h
> > @@ -2391,6 +2391,45 @@ TRACE_EVENT(nfsd_lookup_dentry,
> >  	TP_printk("xid=0x%08x fh_hash=0x%08x name=%s",
> >  		  __entry->xid, __entry->fh_hash, __get_str(name))
> >  );
> > +
> > +DECLARE_EVENT_CLASS(nfsd_vfs_create_class,
> > +	TP_PROTO(struct svc_rqst *rqstp,
> > +		 struct svc_fh *fhp,
> > +		 umode_t type,
> > +		 const char *name,
> > +		 unsigned int len),
> > +	TP_ARGS(rqstp, fhp, type, name, len),
> > +	TP_STRUCT__entry(
> > +		SVC_RQST_ENDPOINT_FIELDS(rqstp)
> > +		__field(u32, fh_hash)
> > +		__field(umode_t, type)
> > +		__string_len(name, name, len)
> > +	),
> > +	TP_fast_assign(
> > +		SVC_RQST_ENDPOINT_ASSIGNMENTS(rqstp);
> > +		__entry->fh_hash = knfsd_fh_hash(&fhp->fh_handle);
> > +		__entry->type = type;
> > +		__assign_str(name);
> > +	),
> > +	TP_printk("xid=0x%08x fh_hash=0x%08x type=%s name=%s",
> > +		  __entry->xid, __entry->fh_hash,
> > +		  show_fs_file_type(__entry->type), __get_str(name))
> > +);
> > +
> > +#define DEFINE_NFSD_VFS_CREATE_EVENT(__name)						\
> > +	DEFINE_EVENT(nfsd_vfs_create_class, __name,					\
> > +		     TP_PROTO(struct svc_rqst *rqstp, struct svc_fh *fhp,		\
> > +			      umode_t type, const char *name, unsigned int len),	\
> > +		     TP_ARGS(rqstp, fhp, type, name, len))
> > +
> > +DEFINE_NFSD_VFS_CREATE_EVENT(nfsd_proc_create);
> > +DEFINE_NFSD_VFS_CREATE_EVENT(nfsd_proc_mkdir);
> > +DEFINE_NFSD_VFS_CREATE_EVENT(nfsd3_proc_create);
> > +DEFINE_NFSD_VFS_CREATE_EVENT(nfsd3_proc_mkdir);
> > +DEFINE_NFSD_VFS_CREATE_EVENT(nfsd3_proc_mknod);
> > +DEFINE_NFSD_VFS_CREATE_EVENT(nfsd4_create);
> > +DEFINE_NFSD_VFS_CREATE_EVENT(nfsd4_create_file);
> 
> I think we would be better off with one or two new trace points in
> nfsd_create() and nfsd_create_setattr() instead of all of these...
> 
> Unless I've missed what you are trying to observe...?
>

I'll look into doing it that way.

> 
> > +
> >  #endif /* _NFSD_TRACE_H */
> >  
> >  #undef TRACE_INCLUDE_PATH
> > 
> 
> 

-- 
Jeff Layton <jlayton@xxxxxxxxxx>