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

From: Chuck Lever
Date: Wed Apr 09 2025 - 11:40:55 EST

On 4/9/25 11:38 AM, Chuck Lever wrote:
> On 4/9/25 11:36 AM, Jeff Layton wrote:
>> 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.
>
> AIUI, the compiler will complain in that case. If we need to keep this
> function here, then this is a legitimate use for "inline".

or maybe_unused.


>> 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
>>>>
>>>
>>>
>>
>
>


--
Chuck Lever