xfs: increase number of ACL entries for V5 superblocks

The limit of 25 ACL entries is arbitrary, but baked into the on-disk
format.  For version 5 superblocks, increase it to the maximum nuber
of ACLs that can fit into a single xattr.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Mark Tinguely <tinuguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

(cherry picked from commit 5c87d4bc1a86bd6e6754ac3d6e111d776ddcfe57)

2 files changed, 42 insertions, 20 deletions

diff --git a/fs/xfs/xfs_acl.c b/fs/xfs/xfs_acl.c
index 1d32f1d52763..306d883d89bc 100644
--- a/fs/xfs/xfs_acl.c
+++ b/fs/xfs/xfs_acl.c
@@ -21,6 +21,8 @@
 #include "xfs_bmap_btree.h"
 #include "xfs_inode.h"
 #include "xfs_vnodeops.h"
+#include "xfs_sb.h"
+#include "xfs_mount.h"
 #include "xfs_trace.h"
 #include <linux/slab.h>
 #include <linux/xattr.h>
@@ -34,7 +36,9 @@
  */
 
 STATIC struct posix_acl *
-xfs_acl_from_disk(struct xfs_acl *aclp)
+xfs_acl_from_disk(
+        struct xfs_acl  *aclp,
+        int             max_entries)
 {
         struct posix_acl_entry *acl_e;
         struct posix_acl *acl;
@@ -42,7 +46,7 @@ xfs_acl_from_disk(struct xfs_acl *aclp)
         unsigned int count, i;
 
         count = be32_to_cpu(aclp->acl_cnt);
-        if (count > XFS_ACL_MAX_ENTRIES)
+        if (count > max_entries)
                 return ERR_PTR(-EFSCORRUPTED);
 
         acl = posix_acl_alloc(count, GFP_KERNEL);
@@ -108,9 +112,9 @@ xfs_get_acl(struct inode *inode, int type)
         struct xfs_inode *ip = XFS_I(inode);
         struct posix_acl *acl;
         struct xfs_acl *xfs_acl;
-        int len = sizeof(struct xfs_acl);
         unsigned char *ea_name;
         int error;
+        int len;
 
         acl = get_cached_acl(inode, type);
         if (acl != ACL_NOT_CACHED)
@@ -133,8 +137,8 @@ xfs_get_acl(struct inode *inode, int type)
          * If we have a cached ACLs value just return it, not need to
          * go out to the disk.
          */
-
-        xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL);
+        len = XFS_ACL_MAX_SIZE(ip->i_mount);
+        xfs_acl = kzalloc(len, GFP_KERNEL);
         if (!xfs_acl)
                 return ERR_PTR(-ENOMEM);
 
@@ -153,7 +157,7 @@ xfs_get_acl(struct inode *inode, int type)
                 goto out;
         }
 
-        acl = xfs_acl_from_disk(xfs_acl);
+        acl = xfs_acl_from_disk(xfs_acl, XFS_ACL_MAX_ENTRIES(ip->i_mount));
         if (IS_ERR(acl))
                 goto out;
 
@@ -189,16 +193,17 @@ xfs_set_acl(struct inode *inode, int type, struct posix_acl *acl)
 
         if (acl) {
                 struct xfs_acl *xfs_acl;
-                int len;
+                int len = XFS_ACL_MAX_SIZE(ip->i_mount);
 
-                xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL);
+                xfs_acl = kzalloc(len, GFP_KERNEL);
                 if (!xfs_acl)
                         return -ENOMEM;
 
                 xfs_acl_to_disk(xfs_acl, acl);
-                len = sizeof(struct xfs_acl) -
-                        (sizeof(struct xfs_acl_entry) *
-                         (XFS_ACL_MAX_ENTRIES - acl->a_count));
+
+                /* subtract away the unused acl entries */
+                len -= sizeof(struct xfs_acl_entry) *
+                         (XFS_ACL_MAX_ENTRIES(ip->i_mount) - acl->a_count);
 
                 error = -xfs_attr_set(ip, ea_name, (unsigned char *)xfs_acl,
                                 len, ATTR_ROOT);
@@ -243,7 +248,7 @@ xfs_set_mode(struct inode *inode, umode_t mode)
 static int
 xfs_acl_exists(struct inode *inode, unsigned char *name)
 {
-        int len = sizeof(struct xfs_acl);
+        int len = XFS_ACL_MAX_SIZE(XFS_M(inode->i_sb));
 
         return (xfs_attr_get(XFS_I(inode), name, NULL, &len,
                             ATTR_ROOT|ATTR_KERNOVAL) == 0);
@@ -379,7 +384,7 @@ xfs_xattr_acl_set(struct dentry *dentry, const char *name,
                 goto out_release;
 
         error = -EINVAL;
-        if (acl->a_count > XFS_ACL_MAX_ENTRIES)
+        if (acl->a_count > XFS_ACL_MAX_ENTRIES(XFS_M(inode->i_sb)))
                 goto out_release;
 
         if (type == ACL_TYPE_ACCESS) {
diff --git a/fs/xfs/xfs_acl.h b/fs/xfs/xfs_acl.h
index 39632d941354..4016a567b83c 100644
--- a/fs/xfs/xfs_acl.h
+++ b/fs/xfs/xfs_acl.h
@@ -22,19 +22,36 @@ struct inode;
 struct posix_acl;
 struct xfs_inode;
 
-#define XFS_ACL_MAX_ENTRIES 25
 #define XFS_ACL_NOT_PRESENT (-1)
 
 /* On-disk XFS access control list structure */
+struct xfs_acl_entry {
+        __be32  ae_tag;
+        __be32  ae_id;
+        __be16  ae_perm;
+        __be16  ae_pad;         /* fill the implicit hole in the structure */
+};
+
 struct xfs_acl {
-        __be32          acl_cnt;
-        struct xfs_acl_entry {
-                __be32  ae_tag;
-                __be32  ae_id;
-                __be16  ae_perm;
-        } acl_entry[XFS_ACL_MAX_ENTRIES];
+        __be32                  acl_cnt;
+        struct xfs_acl_entry    acl_entry[0];
 };
 
+/*
+ * The number of ACL entries allowed is defined by the on-disk format.
+ * For v4 superblocks, that is limited to 25 entries. For v5 superblocks, it is
+ * limited only by the maximum size of the xattr that stores the information.
+ */
+#define XFS_ACL_MAX_ENTRIES(mp) \
+        (xfs_sb_version_hascrc(&mp->m_sb) \
+                ?  (XATTR_SIZE_MAX - sizeof(struct xfs_acl)) / \
+                                                sizeof(struct xfs_acl_entry) \
+                : 25)
+
+#define XFS_ACL_MAX_SIZE(mp) \
+        (sizeof(struct xfs_acl) + \
+                sizeof(struct xfs_acl_entry) * XFS_ACL_MAX_ENTRIES((mp)))
+
 /* On-disk XFS extended attribute names */
 #define SGI_ACL_FILE            (unsigned char *)"SGI_ACL_FILE"
 #define SGI_ACL_DEFAULT         (unsigned char *)"SGI_ACL_DEFAULT"