Re: [PATCH v2] nfsd: map EBUSY to NFS4ERR_ACCESS for all operations

[Jeff Layton <jlayton@kernel.org>]

On Tue, 2025-01-21 at 11:39 +0100, Amir Goldstein wrote:
> Commit 466e16f0920f3 ("nfsd: check for EBUSY from vfs_rmdir/vfs_unink.")
> mapped EBUSY host error from rmdir/unlink operation to avoid unknown
> error server warning.
> 
> The same reason that casued the reported EBUSY on rmdir() (dir is a
> local mount point in some other bind mount) could also cause EBUSY on
> rename and some filesystems (e.g. FUSE) can return EBUSY on other
> operations like open().
> 
> Therefore, to avoid unknown error warning in server, we need to map
> EBUSY for all operations.
> 
> The original fix mapped EBUSY to NFS4ERR_FILE_OPEN in v4 server and
> to NFS4ERR_ACCESS in v2/v3 server.
> 
> During the discussion on this issue, Trond claimed that the mapping
> made from EBUSY to NFS4ERR_FILE_OPEN was incorrect according to the
> protocol spec and specifically, NFS4ERR_FILE_OPEN is not expected
> for directories.
> 
> To keep things simple and consistent and avoid the server warning,
> map EBUSY to NFS4ERR_ACCESS for all operations in all protocol versions.
> 
> Note that the mapping of NFS4ERR_FILE_OPEN to NFSERR_ACCESS in
> nfsd3_map_status() and nfsd_map_status() remains for possible future
> return of NFS4ERR_FILE_OPEN in a more specific use case (e.g. an unlink
> of a sillyrenamed non-dir).
> 
> Fixes: 466e16f0920f3 ("nfsd: check for EBUSY from vfs_rmdir/vfs_unink.")
> Link: https://lore.kernel.org/linux-nfs/20250120172016.397916-1-amir73il@gmail.com/
> Cc: Trond Myklebust <trondmy@hammerspace.com>
> Cc: NeilBrown <neilb@suse.de>
> Signed-off-by: Amir Goldstein <amir73il@gmail.com>
> ---
>  fs/nfsd/vfs.c | 10 ++--------
>  1 file changed, 2 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
> index 29cb7b812d713..290c7db8a6180 100644
> --- a/fs/nfsd/vfs.c
> +++ b/fs/nfsd/vfs.c
> @@ -69,6 +69,7 @@ nfserrno (int errno)
>  		{ nfserr_fbig, -E2BIG },
>  		{ nfserr_stale, -EBADF },
>  		{ nfserr_acces, -EACCES },
> +		{ nfserr_acces, -EBUSY},
>  		{ nfserr_exist, -EEXIST },
>  		{ nfserr_xdev, -EXDEV },
>  		{ nfserr_mlink, -EMLINK },
> @@ -2006,14 +2007,7 @@ nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
>  out_drop_write:
>  	fh_drop_write(fhp);
>  out_nfserr:
> -	if (host_err == -EBUSY) {
> -		/* name is mounted-on. There is no perfect
> -		 * error status.
> -		 */
> -		err = nfserr_file_open;
> -	} else {
> -		err = nfserrno(host_err);
> -	}
> +	err = nfserrno(host_err);
>  out:
>  	return err;
>  out_unlock:

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