Re: [PATCH 7/8] NFSD: use (un)lock_inode instead of fh_(un)lock for file operations

[Jeff Layton <jlayton@kernel.org>]

On Wed, 2022-07-06 at 14:18 +1000, NeilBrown wrote:
> When locking a file to access ACLs and xattrs etc, use explicit locking
> with inode_lock() instead of fh_lock().  This means that the calls to
> fh_fill_pre/post_attr() are also explicit which improves readability and
> allows us to place them only where they are needed.  Only the xattr
> calls need pre/post information.
> 
> When locking a file we don't need I_MUTEX_PARENT as the file is not a
> parent of anything, so we can use inode_lock() directly rather than the
> inode_lock_nested() call that fh_lock() uses.
> 
> Signed-off-by: NeilBrown <neilb@suse.de>
> ---
>  fs/nfsd/nfs2acl.c   |    6 +++---
>  fs/nfsd/nfs3acl.c   |    4 ++--
>  fs/nfsd/nfs4acl.c   |    7 +++----
>  fs/nfsd/nfs4state.c |    8 ++++----
>  fs/nfsd/vfs.c       |   25 ++++++++++++-------------
>  5 files changed, 24 insertions(+), 26 deletions(-)
> 
> diff --git a/fs/nfsd/nfs2acl.c b/fs/nfsd/nfs2acl.c
> index b5760801d377..9edd3c1a30fb 100644
> --- a/fs/nfsd/nfs2acl.c
> +++ b/fs/nfsd/nfs2acl.c
> @@ -111,7 +111,7 @@ static __be32 nfsacld_proc_setacl(struct svc_rqst *rqstp)
>  	if (error)
>  		goto out_errno;
>  
> -	fh_lock(fh);
> +	inode_lock(inode);
>  
>  	error = set_posix_acl(&init_user_ns, inode, ACL_TYPE_ACCESS,
>  			      argp->acl_access);
> @@ -122,7 +122,7 @@ static __be32 nfsacld_proc_setacl(struct svc_rqst *rqstp)
>  	if (error)
>  		goto out_drop_lock;
>  
> -	fh_unlock(fh);
> +	inode_unlock(inode);
>  
>  	fh_drop_write(fh);
>  
> @@ -136,7 +136,7 @@ static __be32 nfsacld_proc_setacl(struct svc_rqst *rqstp)
>  	return rpc_success;
>  
>  out_drop_lock:
> -	fh_unlock(fh);
> +	inode_unlock(inode);
>  	fh_drop_write(fh);
>  out_errno:
>  	resp->status = nfserrno(error);
> diff --git a/fs/nfsd/nfs3acl.c b/fs/nfsd/nfs3acl.c
> index 35b2ebda14da..9446c6743664 100644
> --- a/fs/nfsd/nfs3acl.c
> +++ b/fs/nfsd/nfs3acl.c
> @@ -101,7 +101,7 @@ static __be32 nfsd3_proc_setacl(struct svc_rqst *rqstp)
>  	if (error)
>  		goto out_errno;
>  
> -	fh_lock(fh);
> +	inode_lock(inode);
>  
>  	error = set_posix_acl(&init_user_ns, inode, ACL_TYPE_ACCESS,
>  			      argp->acl_access);
> @@ -111,7 +111,7 @@ static __be32 nfsd3_proc_setacl(struct svc_rqst *rqstp)
>  			      argp->acl_default);
>  
>  out_drop_lock:
> -	fh_unlock(fh);
> +	inode_unlock(inode);
>  	fh_drop_write(fh);
>  out_errno:
>  	resp->status = nfserrno(error);
> diff --git a/fs/nfsd/nfs4acl.c b/fs/nfsd/nfs4acl.c
> index 5c9b7e01e8ca..a33cacf62ea0 100644
> --- a/fs/nfsd/nfs4acl.c
> +++ b/fs/nfsd/nfs4acl.c
> @@ -781,19 +781,18 @@ nfsd4_set_nfs4_acl(struct svc_rqst *rqstp, struct svc_fh *fhp,
>  	if (host_error < 0)
>  		goto out_nfserr;
>  
> -	fh_lock(fhp);
> +	inode_lock(inode);
>  
>  	host_error = set_posix_acl(&init_user_ns, inode, ACL_TYPE_ACCESS, pacl);
>  	if (host_error < 0)
>  		goto out_drop_lock;
>  
> -	if (S_ISDIR(inode->i_mode)) {
> +	if (S_ISDIR(inode->i_mode))
>  		host_error = set_posix_acl(&init_user_ns, inode,
>  					   ACL_TYPE_DEFAULT, dpacl);
> -	}
>  
>  out_drop_lock:
> -	fh_unlock(fhp);
> +	inode_unlock(inode);
>  
>  	posix_acl_release(pacl);
>  	posix_acl_release(dpacl);
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 9d1a3e131c49..307317ba9aff 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -7322,21 +7322,21 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>  static __be32 nfsd_test_lock(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file_lock *lock)
>  {
>  	struct nfsd_file *nf;
> +	struct inode *inode = fhp->fh_dentry->d_inode;
>  	__be32 err;
>  
>  	err = nfsd_file_acquire(rqstp, fhp, NFSD_MAY_READ, &nf);
>  	if (err)
>  		return err;
> -	fh_lock(fhp); /* to block new leases till after test_lock: */
> -	err = nfserrno(nfsd_open_break_lease(fhp->fh_dentry->d_inode,
> -							NFSD_MAY_READ));
> +	inode_lock(inode); /* to block new leases till after test_lock: */
> +	err = nfserrno(nfsd_open_break_lease(inode, NFSD_MAY_READ));
>  	if (err)
>  		goto out;
>  	lock->fl_file = nf->nf_file;
>  	err = nfserrno(vfs_test_lock(nf->nf_file, lock));
>  	lock->fl_file = NULL;
>  out:
> -	fh_unlock(fhp);
> +	inode_unlock(inode);
>  	nfsd_file_put(nf);
>  	return err;
>  }
> diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
> index 2ca748aa83bb..2526615285ca 100644
> --- a/fs/nfsd/vfs.c
> +++ b/fs/nfsd/vfs.c
> @@ -444,7 +444,7 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap,
>  			return err;
>  	}
>  
> -	fh_lock(fhp);
> +	inode_lock(inode);
>  	if (size_change) {
>  		/*
>  		 * RFC5661, Section 18.30.4:
> @@ -480,7 +480,7 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap,
>  	host_err = notify_change(&init_user_ns, dentry, iap, NULL);
>  
>  out_unlock:
> -	fh_unlock(fhp);
> +	inode_unlock(inode);
>  	if (size_change)
>  		put_write_access(inode);
>  out:
> @@ -2196,12 +2196,8 @@ nfsd_listxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char **bufp,
>  }
>  
>  /*
> - * Removexattr and setxattr need to call fh_lock to both lock the inode
> - * and set the change attribute. Since the top-level vfs_removexattr
> - * and vfs_setxattr calls already do their own inode_lock calls, call
> - * the _locked variant. Pass in a NULL pointer for delegated_inode,
> - * and let the client deal with NFS4ERR_DELAY (same as with e.g.
> - * setattr and remove).
> + * Pass in a NULL pointer for delegated_inode, and let the client deal
> + * with NFS4ERR_DELAY (same as with e.g.  setattr and remove).
>   */
>  __be32
>  nfsd_removexattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name)
> @@ -2217,12 +2213,14 @@ nfsd_removexattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name)
>  	if (ret)
>  		return nfserrno(ret);
>  
> -	fh_lock(fhp);
> +	inode_lock(fhp->fh_dentry->d_inode);
> +	fh_fill_pre_attrs(fhp);
>  
>  	ret = __vfs_removexattr_locked(&init_user_ns, fhp->fh_dentry,
>  				       name, NULL);
>  
> -	fh_unlock(fhp);
> +	fh_fill_post_attrs(fhp);
> +	inode_unlock(fhp->fh_dentry->d_inode);
>  	fh_drop_write(fhp);
>  
>  	return nfsd_xattr_errno(ret);
> @@ -2242,12 +2240,13 @@ nfsd_setxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name,
>  	ret = fh_want_write(fhp);
>  	if (ret)
>  		return nfserrno(ret);
> -	fh_lock(fhp);
> +	inode_lock(fhp->fh_dentry->d_inode);
> +	fh_fill_pre_attrs(fhp);
>  
>  	ret = __vfs_setxattr_locked(&init_user_ns, fhp->fh_dentry, name, buf,
>  				    len, flags, NULL);
> -
> -	fh_unlock(fhp);
> +	fh_fill_post_attrs(fhp);
> +	inode_unlock(fhp->fh_dentry->d_inode);
>  	fh_drop_write(fhp);
>  
>  	return nfsd_xattr_errno(ret);
> 
> 

Reviewed-by: Jeff Layton <jlayton@kernel.org>