NFSv4: include bitmap in nfsv4 get acl data
The NFSv4 bitmap size is unbounded: a server can return an arbitrary
sized bitmap in an FATTR4_WORD0_ACL request. Replace using the
nfs4_fattr_bitmap_maxsz as a guess to the maximum bitmask returned by a server
with the inclusion of the bitmap (xdr length plus bitmasks) and the acl data
xdr length to the (cached) acl page data.
This is a general solution to commit e5012d1f "NFSv4.1: update
nfs4_fattr_bitmap_maxsz" and fixes hitting a BUG_ON in xdr_shrink_bufhead
when getting ACLs.
Fix a bug in decode_getacl that returned -EINVAL on ACLs > page when getxattr
was called with a NULL buffer, preventing ACL > PAGE_SIZE from being retrieved.
Cc: stable@kernel.org
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index fcc2408..3b10801 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -3426,19 +3426,6 @@
*/
#define NFS4ACL_MAXPAGES (XATTR_SIZE_MAX >> PAGE_CACHE_SHIFT)
-static void buf_to_pages(const void *buf, size_t buflen,
- struct page **pages, unsigned int *pgbase)
-{
- const void *p = buf;
-
- *pgbase = offset_in_page(buf);
- p -= *pgbase;
- while (p < buf + buflen) {
- *(pages++) = virt_to_page(p);
- p += PAGE_CACHE_SIZE;
- }
-}
-
static int buf_to_pages_noslab(const void *buf, size_t buflen,
struct page **pages, unsigned int *pgbase)
{
@@ -3535,9 +3522,19 @@
nfs4_set_cached_acl(inode, acl);
}
+/*
+ * The getxattr API returns the required buffer length when called with a
+ * NULL buf. The NFSv4 acl tool then calls getxattr again after allocating
+ * the required buf. On a NULL buf, we send a page of data to the server
+ * guessing that the ACL request can be serviced by a page. If so, we cache
+ * up to the page of ACL data, and the 2nd call to getxattr is serviced by
+ * the cache. If not so, we throw away the page, and cache the required
+ * length. The next getxattr call will then produce another round trip to
+ * the server, this time with the input buf of the required size.
+ */
static ssize_t __nfs4_get_acl_uncached(struct inode *inode, void *buf, size_t buflen)
{
- struct page *pages[NFS4ACL_MAXPAGES];
+ struct page *pages[NFS4ACL_MAXPAGES] = {NULL, };
struct nfs_getaclargs args = {
.fh = NFS_FH(inode),
.acl_pages = pages,
@@ -3552,41 +3549,60 @@
.rpc_argp = &args,
.rpc_resp = &res,
};
- struct page *localpage = NULL;
- int ret;
+ int ret = -ENOMEM, npages, i, acl_len = 0;
- if (buflen < PAGE_SIZE) {
- /* As long as we're doing a round trip to the server anyway,
- * let's be prepared for a page of acl data. */
- localpage = alloc_page(GFP_KERNEL);
- resp_buf = page_address(localpage);
- if (localpage == NULL)
- return -ENOMEM;
- args.acl_pages[0] = localpage;
- args.acl_pgbase = 0;
- args.acl_len = PAGE_SIZE;
- } else {
- resp_buf = buf;
- buf_to_pages(buf, buflen, args.acl_pages, &args.acl_pgbase);
+ npages = (buflen + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ /* 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;
+
+ for (i = 0; i < npages; i++) {
+ pages[i] = alloc_page(GFP_KERNEL);
+ if (!pages[i])
+ goto out_free;
}
- ret = nfs4_call_sync(NFS_SERVER(inode)->client, NFS_SERVER(inode), &msg, &args.seq_args, &res.seq_res, 0);
+ if (npages > 1) {
+ /* for decoding across pages */
+ args.acl_scratch = alloc_page(GFP_KERNEL);
+ if (!args.acl_scratch)
+ goto out_free;
+ }
+ args.acl_len = npages * PAGE_SIZE;
+ args.acl_pgbase = 0;
+ /* Let decode_getfacl know not to fail if the ACL data is larger than
+ * the page we send as a guess */
+ if (buf == NULL)
+ res.acl_flags |= NFS4_ACL_LEN_REQUEST;
+ resp_buf = page_address(pages[0]);
+
+ dprintk("%s buf %p buflen %ld npages %d args.acl_len %ld\n",
+ __func__, buf, buflen, npages, args.acl_len);
+ ret = nfs4_call_sync(NFS_SERVER(inode)->client, NFS_SERVER(inode),
+ &msg, &args.seq_args, &res.seq_res, 0);
if (ret)
goto out_free;
- if (res.acl_len > args.acl_len)
- nfs4_write_cached_acl(inode, NULL, res.acl_len);
+
+ acl_len = res.acl_len - res.acl_data_offset;
+ if (acl_len > args.acl_len)
+ nfs4_write_cached_acl(inode, NULL, acl_len);
else
- nfs4_write_cached_acl(inode, resp_buf, res.acl_len);
+ nfs4_write_cached_acl(inode, resp_buf + res.acl_data_offset,
+ acl_len);
if (buf) {
ret = -ERANGE;
- if (res.acl_len > buflen)
+ if (acl_len > buflen)
goto out_free;
- if (localpage)
- memcpy(buf, resp_buf, res.acl_len);
+ _copy_from_pages(buf, pages, res.acl_data_offset,
+ res.acl_len);
}
- ret = res.acl_len;
+ ret = acl_len;
out_free:
- if (localpage)
- __free_page(localpage);
+ for (i = 0; i < npages; i++)
+ if (pages[i])
+ __free_page(pages[i]);
+ if (args.acl_scratch)
+ __free_page(args.acl_scratch);
return ret;
}
@@ -3617,6 +3633,8 @@
nfs_zap_acl_cache(inode);
ret = nfs4_read_cached_acl(inode, buf, buflen);
if (ret != -ENOENT)
+ /* -ENOENT is returned if there is no ACL or if there is an ACL
+ * but no cached acl data, just the acl length */
return ret;
return nfs4_get_acl_uncached(inode, buf, buflen);
}