Re: [PATCH] EXPORTFS: Don't return NULL from fh_to_dentry()/fh_to_parent()[ver #4]

[Hugh Dickins]

On Fri, 5 Dec 2008, David Howells wrote:

> Returning NULL from fh_to_dentry() and fh_to_parent() is not permitted, so
> return -ESTALE instead.  exportfs_decode_fh() does not check for NULL, but
> will try to dereference it as IS_ERR() does not check for it.
> 
> The generic_fh_to_dentry() and generic_fh_to_parent() functions also no longer
> return NULL, but return -ESTALE instead.
> 
> Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
> Acked-by: J. Bruce Fields <bfields@xxxxxxxxxxxxxx>

Acked-by: Hugh Dickins <hugh@xxxxxxxxxxx>

Phew!  Thanks.

> ---
> 
>  fs/fat/inode.c                |    2 +-
>  fs/fuse/inode.c               |    4 ++--
>  fs/gfs2/ops_export.c          |    4 ++--
>  fs/isofs/export.c             |    4 ++--
>  fs/libfs.c                    |    4 ++--
>  fs/ocfs2/export.c             |    4 ++--
>  fs/udf/namei.c                |    4 ++--
>  fs/xfs/linux-2.6/xfs_export.c |    2 +-
>  mm/shmem.c                    |   14 +++++++-------
>  9 files changed, 21 insertions(+), 21 deletions(-)
> 
> 
> diff --git a/fs/fat/inode.c b/fs/fat/inode.c
> index d937aaf..cac84f2 100644
> --- a/fs/fat/inode.c
> +++ b/fs/fat/inode.c
> @@ -657,7 +657,7 @@ static struct dentry *fat_fh_to_dentry(struct super_block *sb,
>  	u32 *fh = fid->raw;
>  
>  	if (fh_len < 5 || fh_type != 3)
> -		return NULL;
> +		return ERR_PTR(-ESTALE);
>  
>  	inode = ilookup(sb, fh[0]);
>  	if (!inode || inode->i_generation != fh[1]) {
> diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
> index 2e99f34..0eb8990 100644
> --- a/fs/fuse/inode.c
> +++ b/fs/fuse/inode.c
> @@ -653,7 +653,7 @@ static struct dentry *fuse_fh_to_dentry(struct super_block *sb,
>  	struct fuse_inode_handle handle;
>  
>  	if ((fh_type != 0x81 && fh_type != 0x82) || fh_len < 3)
> -		return NULL;
> +		return ERR_PTR(-ESTALE);
>  
>  	handle.nodeid = (u64) fid->raw[0] << 32;
>  	handle.nodeid |= (u64) fid->raw[1];
> @@ -667,7 +667,7 @@ static struct dentry *fuse_fh_to_parent(struct super_block *sb,
>  	struct fuse_inode_handle parent;
>  
>  	if (fh_type != 0x82 || fh_len < 6)
> -		return NULL;
> +		return ERR_PTR(-ESTALE);
>  
>  	parent.nodeid = (u64) fid->raw[3] << 32;
>  	parent.nodeid |= (u64) fid->raw[4];
> diff --git a/fs/gfs2/ops_export.c b/fs/gfs2/ops_export.c
> index bbb8c36..2864873 100644
> --- a/fs/gfs2/ops_export.c
> +++ b/fs/gfs2/ops_export.c
> @@ -254,7 +254,7 @@ static struct dentry *gfs2_fh_to_dentry(struct super_block *sb, struct fid *fid,
>  		this.no_addr |= be32_to_cpu(fh[3]);
>  		return gfs2_get_dentry(sb, &this);
>  	default:
> -		return NULL;
> +		return ERR_PTR(-ESTALE);
>  	}
>  }
>  
> @@ -273,7 +273,7 @@ static struct dentry *gfs2_fh_to_parent(struct super_block *sb, struct fid *fid,
>  		parent.no_addr |= be32_to_cpu(fh[7]);
>  		return gfs2_get_dentry(sb, &parent);
>  	default:
> -		return NULL;
> +		return ERR_PTR(-ESTALE);
>  	}
>  }
>  
> diff --git a/fs/isofs/export.c b/fs/isofs/export.c
> index e81a305..1b4ee23 100644
> --- a/fs/isofs/export.c
> +++ b/fs/isofs/export.c
> @@ -164,7 +164,7 @@ static struct dentry *isofs_fh_to_dentry(struct super_block *sb,
>  	struct isofs_fid *ifid = (struct isofs_fid *)fid;
>  
>  	if (fh_len < 3 || fh_type > 2)
> -		return NULL;
> +		return ERR_PTR(-ESTALE);
>  
>  	return isofs_export_iget(sb, ifid->block, ifid->offset,
>  			ifid->generation);
> @@ -176,7 +176,7 @@ static struct dentry *isofs_fh_to_parent(struct super_block *sb,
>  	struct isofs_fid *ifid = (struct isofs_fid *)fid;
>  
>  	if (fh_type != 2)
> -		return NULL;
> +		return ERR_PTR(-ESTALE);
>  
>  	return isofs_export_iget(sb,
>  			fh_len > 2 ? ifid->parent_block : 0,
> diff --git a/fs/libfs.c b/fs/libfs.c
> index e960a83..4fe5b5b 100644
> --- a/fs/libfs.c
> +++ b/fs/libfs.c
> @@ -751,7 +751,7 @@ struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid,
>  	struct inode *inode = NULL;
>  
>  	if (fh_len < 2)
> -		return NULL;
> +		return ERR_PTR(-ESTALE);
>  
>  	switch (fh_type) {
>  	case FILEID_INO32_GEN:
> @@ -784,7 +784,7 @@ struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid,
>  	struct inode *inode = NULL;
>  
>  	if (fh_len <= 2)
> -		return NULL;
> +		return ERR_PTR(-ESTALE);
>  
>  	switch (fh_type) {
>  	case FILEID_INO32_GEN_PARENT:
> diff --git a/fs/ocfs2/export.c b/fs/ocfs2/export.c
> index 2f27b33..0f1c80f 100644
> --- a/fs/ocfs2/export.c
> +++ b/fs/ocfs2/export.c
> @@ -182,7 +182,7 @@ static struct dentry *ocfs2_fh_to_dentry(struct super_block *sb,
>  	struct ocfs2_inode_handle handle;
>  
>  	if (fh_len < 3 || fh_type > 2)
> -		return NULL;
> +		return ERR_PTR(-ESTALE);
>  
>  	handle.ih_blkno = (u64)le32_to_cpu(fid->raw[0]) << 32;
>  	handle.ih_blkno |= (u64)le32_to_cpu(fid->raw[1]);
> @@ -196,7 +196,7 @@ static struct dentry *ocfs2_fh_to_parent(struct super_block *sb,
>  	struct ocfs2_inode_handle parent;
>  
>  	if (fh_type != 2 || fh_len < 6)
> -		return NULL;
> +		return ERR_PTR(-ESTALE);
>  
>  	parent.ih_blkno = (u64)le32_to_cpu(fid->raw[3]) << 32;
>  	parent.ih_blkno |= (u64)le32_to_cpu(fid->raw[4]);
> diff --git a/fs/udf/namei.c b/fs/udf/namei.c
> index f84bfaa..e1a1c16 100644
> --- a/fs/udf/namei.c
> +++ b/fs/udf/namei.c
> @@ -1297,7 +1297,7 @@ static struct dentry *udf_fh_to_dentry(struct super_block *sb,
>  	if ((fh_len != 3 && fh_len != 5) ||
>  	    (fh_type != FILEID_UDF_WITH_PARENT &&
>  	     fh_type != FILEID_UDF_WITHOUT_PARENT))
> -		return NULL;
> +		return ERR_PTR(-ESTALE);
>  
>  	return udf_nfs_get_inode(sb, fid->udf.block, fid->udf.partref,
>  			fid->udf.generation);
> @@ -1307,7 +1307,7 @@ static struct dentry *udf_fh_to_parent(struct super_block *sb,
>  				       struct fid *fid, int fh_len, int fh_type)
>  {
>  	if (fh_len != 5 || fh_type != FILEID_UDF_WITH_PARENT)
> -		return NULL;
> +		return ERR_PTR(-ESTALE);
>  
>  	return udf_nfs_get_inode(sb, fid->udf.parent_block,
>  				 fid->udf.parent_partref,
> diff --git a/fs/xfs/linux-2.6/xfs_export.c b/fs/xfs/linux-2.6/xfs_export.c
> index 7f7abec..f9a51c4 100644
> --- a/fs/xfs/linux-2.6/xfs_export.c
> +++ b/fs/xfs/linux-2.6/xfs_export.c
> @@ -150,7 +150,7 @@ xfs_fs_fh_to_dentry(struct super_block *sb, struct fid *fid,
>  	struct inode		*inode = NULL;
>  
>  	if (fh_len < xfs_fileid_length(fileid_type))
> -		return NULL;
> +		return ERR_PTR(-ESTALE);
>  
>  	switch (fileid_type) {
>  	case FILEID_INO32_GEN_PARENT:
> diff --git a/mm/shmem.c b/mm/shmem.c
> index f1b0d48..c9bdbf7 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -2050,21 +2050,21 @@ static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
>  		struct fid *fid, int fh_len, int fh_type)
>  {
>  	struct inode *inode;
> -	struct dentry *dentry = NULL;
> +	struct dentry *dentry;
>  	u64 inum = fid->raw[2];
>  	inum = (inum << 32) | fid->raw[1];
>  
>  	if (fh_len < 3)
> -		return NULL;
> +		return ERR_PTR(-ESTALE);
>  
>  	inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
>  			shmem_match, fid->raw);
> -	if (inode) {
> -		dentry = d_find_alias(inode);
> -		iput(inode);
> -	}
> +	if (!inode)
> +		return ERR_PTR(-ESTALE);
>  
> -	return dentry;
> +	dentry = d_find_alias(inode);
> +	iput(inode);
> +	return dentry ?: ERR_PTR(-ESTALE);
>  }
>  
>  static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len,
--
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