nfsd4: share file descriptors between stateid's

The vfs doesn't really allow us to "upgrade" a file descriptor from
read-only to read-write, and our attempt to do so in nfs4_upgrade_open
is ugly and incomplete.

Move to a different scheme where we keep multiple opens, shared between
open stateid's, in the nfs4_file struct.  Each file will be opened at
most 3 times (for read, write, and read-write), and those opens will be
shared between all clients and openers.  On upgrade we will do another
open if necessary instead of attempting to upgrade an existing open.
We keep count of the number of readers and writers so we know when to
close the shared files.

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
index 72377761270e..b76ac3a82e39 100644
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h
@@ -153,6 +153,7 @@ void		nfsd_lockd_shutdown(void);
 #define nfserr_bad_seqid        cpu_to_be32(NFSERR_BAD_SEQID)
 #define nfserr_symlink          cpu_to_be32(NFSERR_SYMLINK)
 #define nfserr_not_same         cpu_to_be32(NFSERR_NOT_SAME)
+#define nfserr_lock_range       cpu_to_be32(NFSERR_LOCK_RANGE)
 #define nfserr_restorefh        cpu_to_be32(NFSERR_RESTOREFH)
 #define nfserr_attrnotsupp      cpu_to_be32(NFSERR_ATTRNOTSUPP)
 #define nfserr_bad_xdr          cpu_to_be32(NFSERR_BAD_XDR)