nfsd: Avoid strlen conflict in nfsd4_encode_components_esc()

There is an error building nfs4xdr.c with CONFIG_SUNRPC_DEBUG_TRACE=y
and CONFIG_FORTIFY_SOURCE=n due to the local variable strlen conflicting
with the function strlen():

  In file included from include/linux/cpumask.h:11,
                   from arch/x86/include/asm/paravirt.h:21,
                   from arch/x86/include/asm/irqflags.h:102,
                   from include/linux/irqflags.h:18,
                   from include/linux/spinlock.h:59,
                   from include/linux/mmzone.h:8,
                   from include/linux/gfp.h:7,
                   from include/linux/slab.h:16,
                   from fs/nfsd/nfs4xdr.c:37:
  fs/nfsd/nfs4xdr.c: In function 'nfsd4_encode_components_esc':
  include/linux/kernel.h:321:46: error: called object 'strlen' is not a function or function pointer
    321 |                 __trace_puts(_THIS_IP_, str, strlen(str));              \
        |                                              ^~~~~~
  include/linux/kernel.h:265:17: note: in expansion of macro 'trace_puts'
    265 |                 trace_puts(fmt);                        \
        |                 ^~~~~~~~~~
  include/linux/sunrpc/debug.h:34:41: note: in expansion of macro 'trace_printk'
     34 | #  define __sunrpc_printk(fmt, ...)     trace_printk(fmt, ##__VA_ARGS__)
        |                                         ^~~~~~~~~~~~
  include/linux/sunrpc/debug.h:42:17: note: in expansion of macro '__sunrpc_printk'
     42 |                 __sunrpc_printk(fmt, ##__VA_ARGS__);                    \
        |                 ^~~~~~~~~~~~~~~
  include/linux/sunrpc/debug.h:25:9: note: in expansion of macro 'dfprintk'
     25 |         dfprintk(FACILITY, fmt, ##__VA_ARGS__)
        |         ^~~~~~~~
  fs/nfsd/nfs4xdr.c:2646:9: note: in expansion of macro 'dprintk'
   2646 |         dprintk("nfsd4_encode_components(%s)\n", components);
        |         ^~~~~~~
  fs/nfsd/nfs4xdr.c:2643:13: note: declared here
   2643 |         int strlen, count=0;
        |             ^~~~~~

This dprintk() instance is not particularly useful, so just remove it
altogether to get rid of the immediate strlen() conflict.

At the same time, eliminate the local strlen variable to avoid potential
conflicts with strlen() in the future.

Fixes: ec7d8e6 ("sunrpc: add a Kconfig option to redirect dfprintk() output to trace buffer")
Signed-off-by: Nathan Chancellor <[email protected]>
Reviewed-by: NeilBrown <[email protected]>
Signed-off-by: Chuck Lever <[email protected]>

Author: nathanchance

fs/nfsd/nfs4xdr.c

@@ -2628,10 +2628,8 @@ static __be32 nfsd4_encode_components_esc(struct xdr_stream *xdr, char sep,
 	__be32 *p;
 	__be32 pathlen;
 	int pathlen_offset;
-	int strlen, count=0;
 	char *str, *end, *next;
-
-	dprintk("nfsd4_encode_components(%s)\n", components);
+	int count = 0;
 
 	pathlen_offset = xdr->buf->len;
 	p = xdr_reserve_space(xdr, 4);
@@ -2658,9 +2656,8 @@ static __be32 nfsd4_encode_components_esc(struct xdr_stream *xdr, char sep,
 			for (; *end && (*end != sep); end++)
 				/* find sep or end of string */;
 
-		strlen = end - str;
-		if (strlen) {
-			if (xdr_stream_encode_opaque(xdr, str, strlen) < 0)
+		if (end > str) {
+			if (xdr_stream_encode_opaque(xdr, str, end - str) < 0)
 				return nfserr_resource;
 			count++;
 		} else