NFSD: Remove NFSERR_EAGAIN

I haven't found an NFSERR_EAGAIN in RFCs 1094, 1813, 7530, or 8881.
None of these RFCs have an NFS status code that match the numeric
value "11".

Based on the meaning of the EAGAIN errno, I presume the use of this
status in NFSD means NFS4ERR_DELAY. So replace the one usage of
nfserr_eagain, and remove it from NFSD's NFS status conversion
tables.

As far as I can tell, NFSERR_EAGAIN has existed since the pre-git
era, but was not actually used by any code until commit f4e44b393389
("NFSD: delay unmount source's export after inter-server copy
completed."), at which time it become possible for NFSD to return
a status code of 11 (which is not valid NFS protocol).

Fixes: f4e44b393389 ("NFSD: delay unmount source's export after inter-server copy completed.")
Cc: [e-mail]
Reviewed-by: NeilBrown <[e-mail]>
Reviewed-by: Jeff Layton <[e-mail]>
Signed-off-by: Chuck Lever <[e-mail]>

fs/nfs_common/common.c

···
 	{ NFSERR_NOENT,		-ENOENT		},
 	{ NFSERR_IO,		-EIO		},
 	{ NFSERR_NXIO,		-ENXIO		},
-/*	{ NFSERR_EAGAIN,	-EAGAIN		}, */
 	{ NFSERR_ACCES,		-EACCES		},
 	{ NFSERR_EXIST,		-EEXIST		},
 	{ NFSERR_XDEV,		-EXDEV		},

fs/nfsd/nfs4proc.c

···
 					(schedule_timeout(20*HZ) == 0)) {
 				finish_wait(&nn->nfsd_ssc_waitq, &wait);
 				kfree(work);
-				return nfserr_eagain;
+				return nfserr_jukebox;
 			}
 			finish_wait(&nn->nfsd_ssc_waitq, &wait);
 			goto try_again;

fs/nfsd/nfsd.h

···
 #define	nfserr_noent		cpu_to_be32(NFSERR_NOENT)
 #define	nfserr_io		cpu_to_be32(NFSERR_IO)
 #define	nfserr_nxio		cpu_to_be32(NFSERR_NXIO)
-#define	nfserr_eagain		cpu_to_be32(NFSERR_EAGAIN)
 #define	nfserr_acces		cpu_to_be32(NFSERR_ACCES)
 #define	nfserr_exist		cpu_to_be32(NFSERR_EXIST)
 #define	nfserr_xdev		cpu_to_be32(NFSERR_XDEV)

include/trace/misc/nfs.h

···
 TRACE_DEFINE_ENUM(NFSERR_NOENT);
 TRACE_DEFINE_ENUM(NFSERR_IO);
 TRACE_DEFINE_ENUM(NFSERR_NXIO);
-TRACE_DEFINE_ENUM(NFSERR_EAGAIN);
 TRACE_DEFINE_ENUM(NFSERR_ACCES);
 TRACE_DEFINE_ENUM(NFSERR_EXIST);
 TRACE_DEFINE_ENUM(NFSERR_XDEV);
···
 		{ NFSERR_NXIO,			"NXIO" }, \
 		{ ECHILD,			"CHILD" }, \
 		{ ETIMEDOUT,			"TIMEDOUT" }, \
-		{ NFSERR_EAGAIN,		"AGAIN" }, \
 		{ NFSERR_ACCES,			"ACCES" }, \
 		{ NFSERR_EXIST,			"EXIST" }, \
 		{ NFSERR_XDEV,			"XDEV" }, \

include/uapi/linux/nfs.h

···
 	NFSERR_NOENT = 2,		/* v2 v3 v4 */
 	NFSERR_IO = 5,			/* v2 v3 v4 */
 	NFSERR_NXIO = 6,		/* v2 v3 v4 */
-	NFSERR_EAGAIN = 11,		/* v2 v3 */
 	NFSERR_ACCES = 13,		/* v2 v3 v4 */
 	NFSERR_EXIST = 17,		/* v2 v3 v4 */
 	NFSERR_XDEV = 18,		/*    v3 v4 */