vfs: check i_nlink limits in vfs_{mkdir,rename_dir,link}

New field of struct super_block - ->s_max_links.  Maximal allowed
value of ->i_nlink or 0; in the latter case all checks still need
to be done in ->link/->mkdir/->rename instances.  Note that this
limit applies both to directoris and to non-directories.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

4 files changed, 1 insertions, 29 deletions

diff --git a/fs/xfs/xfs_rename.c b/fs/xfs/xfs_rename.c
index 866de277079..e44ef7ee8ce 100644
--- a/fs/xfs/xfs_rename.c
+++ b/fs/xfs/xfs_rename.c
@@ -118,17 +118,6 @@ xfs_rename(
         new_parent = (src_dp != target_dp);
         src_is_directory = S_ISDIR(src_ip->i_d.di_mode);
 
-        if (src_is_directory) {
-                /*
-                 * Check for link count overflow on target_dp
-                 */
-                if (target_ip == NULL && new_parent &&
-                    target_dp->i_d.di_nlink >= XFS_MAXLINK) {
-                        error = XFS_ERROR(EMLINK);
-                        goto std_return;
-                }
-        }
-
         xfs_sort_for_rename(src_dp, target_dp, src_ip, target_ip,
                                 inodes, &num_inodes);
 
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index ee5b695c99a..0e4c5c017fb 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -1341,6 +1341,7 @@ xfs_fs_fill_super(
         sb->s_blocksize = mp->m_sb.sb_blocksize;
         sb->s_blocksize_bits = ffs(sb->s_blocksize) - 1;
         sb->s_maxbytes = xfs_max_file_offset(sb->s_blocksize_bits);
+        sb->s_max_links = XFS_MAXLINK;
         sb->s_time_gran = 1;
         set_posix_acl_flag(sb);
 
diff --git a/fs/xfs/xfs_utils.c b/fs/xfs/xfs_utils.c
index 89dbb4a5087..79c05ac85bf 100644
--- a/fs/xfs/xfs_utils.c
+++ b/fs/xfs/xfs_utils.c
@@ -296,8 +296,6 @@ xfs_bumplink(
         xfs_trans_t *tp,
         xfs_inode_t *ip)
 {
-        if (ip->i_d.di_nlink >= XFS_MAXLINK)
-                return XFS_ERROR(EMLINK);
         xfs_trans_ichgtime(tp, ip, XFS_ICHGTIME_CHG);
 
         ASSERT(ip->i_d.di_nlink > 0);
diff --git a/fs/xfs/xfs_vnodeops.c b/fs/xfs/xfs_vnodeops.c
index ebdb88840a4..64981d7e737 100644
--- a/fs/xfs/xfs_vnodeops.c
+++ b/fs/xfs/xfs_vnodeops.c
@@ -917,14 +917,6 @@ xfs_create(
         xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
         unlock_dp_on_error = B_TRUE;
 
-        /*
-         * Check for directory link count overflow.
-         */
-        if (is_dir && dp->i_d.di_nlink >= XFS_MAXLINK) {
-                error = XFS_ERROR(EMLINK);
-                goto out_trans_cancel;
-        }
-
         xfs_bmap_init(&free_list, &first_block);
 
         /*
@@ -1429,14 +1421,6 @@ xfs_link(
         xfs_trans_ijoin(tp, tdp, XFS_ILOCK_EXCL);
 
         /*
-         * If the source has too many links, we can't make any more to it.
-         */
-        if (sip->i_d.di_nlink >= XFS_MAXLINK) {
-                error = XFS_ERROR(EMLINK);
-                goto error_return;
-        }
-
-        /*
          * If we are using project inheritance, we only allow hard link
          * creation in our tree when the project IDs are the same; else
          * the tree quota mechanism could be circumvented.