Re: [PATCH 2/2] NFSv4: fix getacl ERANGE for some ACL buffer sizes

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Thanks, Bruce and Dros!

Anna

On 02/23/2017 02:54 PM, J. Bruce Fields wrote:
> From: Weston Andros Adamson <dros@xxxxxxxxxxxxxxx>
> 
> We're not taking into account that the space needed for the (variable
> length) attr bitmap, with the result that we'd sometimes get a spurious
> ERANGE when the ACL data got close to the end of a page.
> 
> Just add in an extra page to make sure.
> 
> Signed-off-by: Weston Andros Adamson <dros@xxxxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
> ---
>  fs/nfs/nfs4proc.c | 8 ++------
>  1 file changed, 2 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> index 0a0eaecf9676..60501e10625d 100644
> --- a/fs/nfs/nfs4proc.c
> +++ b/fs/nfs/nfs4proc.c
> @@ -5069,7 +5069,7 @@ static void nfs4_write_cached_acl(struct inode *inode, struct page **pages, size
>   */
>  static ssize_t __nfs4_get_acl_uncached(struct inode *inode, void *buf, size_t buflen)
>  {
> -	struct page *pages[NFS4ACL_MAXPAGES] = {NULL, };
> +	struct page *pages[NFS4ACL_MAXPAGES + 1] = {NULL, };
>  	struct nfs_getaclargs args = {
>  		.fh = NFS_FH(inode),
>  		.acl_pages = pages,
> @@ -5083,13 +5083,9 @@ static ssize_t __nfs4_get_acl_uncached(struct inode *inode, void *buf, size_t bu
>  		.rpc_argp = &args,
>  		.rpc_resp = &res,
>  	};
> -	unsigned int npages = DIV_ROUND_UP(buflen, PAGE_SIZE);
> +	unsigned int npages = DIV_ROUND_UP(buflen, PAGE_SIZE) + 1;
>  	int ret = -ENOMEM, i;
>  
> -	/* As long as we're doing a round trip to the server anyway,
> -	 * let's be prepared for a page of acl data. */
> -	if (npages == 0)
> -		npages = 1;
>  	if (npages > ARRAY_SIZE(pages))
>  		return -ERANGE;
>  
> 
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