[PATCH] NFSv4: fix open(O_RDONLY|O_TRUNC) returning EBADF

[Nadav Shemer <nadav@tonian.com>]

Move ATTR_OPEN handling from nfs4_proc_setattr into nfs4_do_setattr

Signed-off-by: Nadav Shemer <nadav@tonian.com>
---
Hello.

I've come across an oddity while testing filesystem coverage
My test creates a non-empty file without write permissions and tries to open it with O_RDONLY|O_TRUNC
It expects EACCES (and gets that for local filesystems and NFSv3) but gets EBADF on NFSv4 (and v4.1)

I found some history on this: In a previous kernel it would just hang due to mishandling the NFS4ERR_OPENMODE exception
http://www.spinics.net/lists/linux-nfs/msg28881.html

A fix for this was introduced (it specifically tests for NFS4ERR_OPENMODE and returns EACCES for the open() case, EBADF otherwise)
http://www.spinics.net/linux/fedora/fedora-kernel/msg03736.html
but another patch was also introduced in the same set which seems to break it (it optimizes away the time modification and removes ATTR_OPEN in nfs4_proc_setattr)
http://www.spinics.net/linux/fedora/fedora-kernel/msg03732.html

By moving the 'Deal with open(O_TRUNC)' bit inside (into nfs4_do_setattr), I got it working again (with no other functional change, as far as I can see)

 fs/nfs/nfs4proc.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 8fbc100..17b9f32 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2180,6 +2180,10 @@ static int nfs4_do_setattr(struct inode *inode, struct rpc_cred *cred,
 		.inode = inode,
 	};
 	int err;
+	int is_o_trunc = sattr->ia_valid & ATTR_OPEN;
+	/* Deal with open(O_TRUNC) */
+	if (sattr->ia_valid & ATTR_OPEN)
+		sattr->ia_valid &= ~(ATTR_MTIME|ATTR_CTIME|ATTR_OPEN);
 	do {
 		err = _nfs4_do_setattr(inode, cred, fattr, sattr, state);
 		switch (err) {
@@ -2193,7 +2197,7 @@ static int nfs4_do_setattr(struct inode *inode, struct rpc_cred *cred,
 			}
 			if (state && !(state->state & FMODE_WRITE)) {
 				err = -EBADF;
-				if (sattr->ia_valid & ATTR_OPEN)
+				if (is_o_trunc)
 					err = -EACCES;
 				goto out;
 			}
@@ -2774,10 +2778,6 @@ nfs4_proc_setattr(struct dentry *dentry, struct nfs_fattr *fattr,
 
 	nfs_fattr_init(fattr);
 	
-	/* Deal with open(O_TRUNC) */
-	if (sattr->ia_valid & ATTR_OPEN)
-		sattr->ia_valid &= ~(ATTR_MTIME|ATTR_CTIME|ATTR_OPEN);
-
 	/* Optimization: if the end result is no change, don't RPC */
 	if ((sattr->ia_valid & ~(ATTR_FILE)) == 0)
 		return 0;
-- 
1.7.11.7