NFSv4: fix getacl ERANGE for some ACL buffer sizes

commit ed92d8c137b7794c2c2aa14479298b9885967607 upstream.

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>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 927a664..8f509a0 100644 (file)
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -3569,7 +3569,7 @@ out:
  */
 static ssize_t __nfs4_get_acl_uncached(struct inode *inode, void *buf, size_t buflen)
 {
  */
 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,
        struct nfs_getaclargs args = {
                .fh = NFS_FH(inode),
                .acl_pages = pages,


@@ -3583,14 +3583,10 @@ static ssize_t __nfs4_get_acl_uncached(struct inode *inode, void *buf, size_t bu
                .rpc_argp = &args,
                .rpc_resp = &res,
        };
                .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;
        size_t acl_len = 0;
 
        int ret = -ENOMEM, i;
        size_t acl_len = 0;
 

-       /* 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;
 
        if (npages > ARRAY_SIZE(pages))
                return -ERANGE;