[PATCH] NFSD: Replace isdotent() macro

[Chuck Lever <cel@kernel.org>]

The VFS provides name_is_dot_dotdot() as the canonical helper for
recognizing the "." and ".." directory entries, and fs/ already uses
it widely. nfsd has instead carried its own open-coded isdotent()
macro that computes the same predicate for non-empty names, a needless
duplicate of shared functionality. The macro reads the first name byte
without first confirming the name is non-empty; name_is_dot_dotdot()
tests the length first, so it never touches a zero-length buffer.
Convert every isdotent() call site to the generic helper and remove the
macro.

Signed-off-by: Chuck Lever <cel@kernel.org>
---
 fs/nfsd/nfs3proc.c |  2 +-
 fs/nfsd/nfs3xdr.c  |  2 +-
 fs/nfsd/nfs4proc.c |  2 +-
 fs/nfsd/nfs4xdr.c  |  4 ++--
 fs/nfsd/nfsd.h     |  3 ---
 fs/nfsd/nfsproc.c  |  2 +-
 fs/nfsd/vfs.c      | 13 +++++++------
 7 files changed, 13 insertions(+), 15 deletions(-)

diff --git a/fs/nfsd/nfs3proc.c b/fs/nfsd/nfs3proc.c
index 42adc5461db0..a14827cfeeb8 100644
--- a/fs/nfsd/nfs3proc.c
+++ b/fs/nfsd/nfs3proc.c
@@ -265,7 +265,7 @@ nfsd3_create_file(struct svc_rqst *rqstp, struct svc_fh *fhp,
 
 	trace_nfsd_vfs_create(rqstp, fhp, S_IFREG, argp->name, argp->len);
 
-	if (isdotent(argp->name, argp->len))
+	if (name_is_dot_dotdot(argp->name, argp->len))
 		return nfserr_exist;
 	if (!(iap->ia_valid & ATTR_MODE))
 		iap->ia_mode = 0;
diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index 2ff9a991a8fb..e481804bb120 100644
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -987,7 +987,7 @@ compose_entry_fh(struct nfsd3_readdirres *cd, struct svc_fh *fhp,
 	dparent = cd->fh.fh_dentry;
 	exp  = cd->fh.fh_export;
 
-	if (isdotent(name, namlen)) {
+	if (name_is_dot_dotdot(name, namlen)) {
 		if (namlen == 2) {
 			dchild = dget_parent(dparent);
 			/*
diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 907b899a90da..654705d1dd37 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -259,7 +259,7 @@ nfsd4_create_file(struct svc_rqst *rqstp, struct svc_fh *fhp,
 	__be32 status;
 	int host_err;
 
-	if (isdotent(open->op_fname, open->op_fnamelen))
+	if (name_is_dot_dotdot(open->op_fname, open->op_fnamelen))
 		return nfserr_exist;
 	if (!(iap->ia_valid & ATTR_MODE))
 		iap->ia_mode = 0;
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 2a0946c630e1..8db16a30d971 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -98,7 +98,7 @@ check_filename(char *str, int len)
 		return nfserr_inval;
 	if (len > NFS4_MAXNAMLEN)
 		return nfserr_nametoolong;
-	if (isdotent(str, len))
+	if (name_is_dot_dotdot(str, len))
 		return nfserr_badname;
 	for (i = 0; i < len; i++)
 		if (str[i] == '/')
@@ -4241,7 +4241,7 @@ nfsd4_encode_entry4(void *ccdv, const char *name, int namlen,
 	__be32 nfserr = nfserr_toosmall;
 
 	/* In nfsv4, "." and ".." never make it onto the wire.. */
-	if (name && isdotent(name, namlen)) {
+	if (name && name_is_dot_dotdot(name, namlen)) {
 		cd->common.err = nfs_ok;
 		return 0;
 	}
diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
index 7c009f07c90b..faf5c1dafa42 100644
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h
@@ -372,9 +372,6 @@ enum {
 #define	nfserr_symlink_not_dir	cpu_to_be32(NFSERR_SYMLINK_NOT_DIR)
 };
 
-/* Check for dir entries '.' and '..' */
-#define isdotent(n, l)	(l < 3 && n[0] == '.' && (l == 1 || n[1] == '.'))
-
 #ifdef CONFIG_NFSD_V4
 
 /* before processing a COMPOUND operation, we have to check that there
diff --git a/fs/nfsd/nfsproc.c b/fs/nfsd/nfsproc.c
index 8873033d1e82..846506445ff9 100644
--- a/fs/nfsd/nfsproc.c
+++ b/fs/nfsd/nfsproc.c
@@ -298,7 +298,7 @@ nfsd_proc_create(struct svc_rqst *rqstp)
 	/* Check for NFSD_MAY_WRITE in nfsd_create if necessary */
 
 	resp->status = nfserr_exist;
-	if (isdotent(argp->name, argp->len))
+	if (name_is_dot_dotdot(argp->name, argp->len))
 		goto done;
 	hosterr = fh_want_write(dirfhp);
 	if (hosterr) {
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index eafdf7b7890f..73506e924dc3 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -255,7 +255,7 @@ nfsd_lookup_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp,
 	exp = exp_get(fhp->fh_export);
 
 	/* Lookup the name, but don't follow links */
-	if (isdotent(name, len)) {
+	if (name_is_dot_dotdot(name, len)) {
 		if (len==1)
 			dentry = dget(dparent);
 		else if (dparent != exp->ex_path.dentry)
@@ -1867,7 +1867,7 @@ nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
 
 	trace_nfsd_vfs_create(rqstp, fhp, type, fname, flen);
 
-	if (isdotent(fname, flen))
+	if (name_is_dot_dotdot(fname, flen))
 		return nfserr_exist;
 
 	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_NOP);
@@ -1969,7 +1969,7 @@ nfsd_symlink(struct svc_rqst *rqstp, struct svc_fh *fhp,
 	if (!flen || path[0] == '\0')
 		goto out;
 	err = nfserr_exist;
-	if (isdotent(fname, flen))
+	if (name_is_dot_dotdot(fname, flen))
 		goto out;
 
 	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_CREATE);
@@ -2046,7 +2046,7 @@ nfsd_link(struct svc_rqst *rqstp, struct svc_fh *ffhp,
 	if (!len)
 		goto out;
 	err = nfserr_exist;
-	if (isdotent(name, len))
+	if (name_is_dot_dotdot(name, len))
 		goto out;
 
 	err = nfs_ok;
@@ -2157,7 +2157,8 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen,
 	tdentry = tfhp->fh_dentry;
 
 	err = nfserr_perm;
-	if (!flen || isdotent(fname, flen) || !tlen || isdotent(tname, tlen))
+	if (!flen || name_is_dot_dotdot(fname, flen) ||
+	    !tlen || name_is_dot_dotdot(tname, tlen))
 		goto out;
 
 	err = nfserr_xdev;
@@ -2279,7 +2280,7 @@ nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
 	trace_nfsd_vfs_unlink(rqstp, fhp, fname, flen);
 
 	err = nfserr_acces;
-	if (!flen || isdotent(fname, flen))
+	if (!flen || name_is_dot_dotdot(fname, flen))
 		goto out;
 	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_REMOVE);
 	if (err)
-- 
2.54.0