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Commit 08e9eac4 authored by Trond Myklebust's avatar Trond Myklebust
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[PATCH] NFSv4: Fix up races in nfs4_proc_setattr() 



 If we do not hold a valid stateid that is open for writes, there is little
 point in doing an extra open of the file, as the RFC does not appear to
 mandate this...

 Make setattr use the correct stateid if we're holding mandatory byte
 range locks.

 Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
parent 202b50dc

fs/nfs/nfs4proc.c

+19 −36
Original line number Diff line number Diff line
@@ -756,11 +756,10 @@ static int _nfs4_do_setattr(struct nfs_server *server, struct nfs_fattr *fattr, 


        fattr->valid = 0;



	if (state != NULL)

	if (state != NULL) {

		msg.rpc_cred = state->owner->so_cred;

	if (sattr->ia_valid & ATTR_SIZE)

		nfs4_copy_stateid(&arg.stateid, state, NULL);

	else

		nfs4_copy_stateid(&arg.stateid, state, current->files);

	} else

		memcpy(&arg.stateid, &zero_stateid, sizeof(arg.stateid));



	return rpc_call_sync(server->client, &msg, 0);
@@ -1124,47 +1123,31 @@ static int 
nfs4_proc_setattr(struct dentry *dentry, struct nfs_fattr *fattr,

		  struct iattr *sattr)

{

	struct rpc_cred *cred;

	struct inode *inode = dentry->d_inode;

	int			size_change = sattr->ia_valid & ATTR_SIZE;

	struct nfs4_state	*state = NULL;

	int need_iput = 0;

	struct nfs4_state *state;

	int status;



	fattr->valid = 0;

	

	if (size_change) {

		struct rpc_cred *cred = rpcauth_lookupcred(NFS_SERVER(inode)->client->cl_auth, 0);

	cred = rpcauth_lookupcred(NFS_SERVER(inode)->client->cl_auth, 0);

	if (IS_ERR(cred))

		return PTR_ERR(cred);

	/* Search for an existing WRITE delegation first */

	state = nfs4_open_delegated(inode, FMODE_WRITE, cred);

	if (!IS_ERR(state)) {

		/* NB: nfs4_open_delegated() bumps the inode->i_count */

		iput(inode);

	} else {

		/* Search for an existing open(O_WRITE) stateid */

		state = nfs4_find_state(inode, cred, FMODE_WRITE);

		if (state == NULL) {

			state = nfs4_open_delegated(dentry->d_inode,

					FMODE_WRITE, cred);

			if (IS_ERR(state))

				state = nfs4_do_open(dentry->d_parent->d_inode,

						dentry, FMODE_WRITE,

						NULL, cred);

			need_iput = 1;

	}

		put_rpccred(cred);

		if (IS_ERR(state))

			return PTR_ERR(state);



		if (state->inode != inode) {

			printk(KERN_WARNING "nfs: raced in setattr (%p != %p), returning -EIO\n", inode, state->inode);

			status = -EIO;

			goto out;

		}

	}

	status = nfs4_do_setattr(NFS_SERVER(inode), fattr,

			NFS_FH(inode), sattr, state);

out:

	if (state) {

		inode = state->inode;

	if (state != NULL)

		nfs4_close_state(state, FMODE_WRITE);

		if (need_iput)

			iput(inode);

	}

	put_rpccred(cred);

	return status;

}