NFSv4: fix getacl ERANGE for some ACL buffer sizes

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@primarydata.com>
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

1 files changed, 2 insertions, 6 deletions

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 92b2805ffb82..1b183686c6d4 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -4954,7 +4954,7 @@ out:
  */
 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,
@@ -4968,13 +4968,9 @@ 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;