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.