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>

2 files changed, 2 insertions, 12 deletions

diff --git a/fs/exofs/namei.c b/fs/exofs/namei.c
index 9dbf0c301030..fc7161d6bf6b 100644
--- a/fs/exofs/namei.c
+++ b/fs/exofs/namei.c
@@ -143,9 +143,6 @@ static int exofs_link(struct dentry *old_dentry, struct inode *dir,
 {
         struct inode *inode = old_dentry->d_inode;
 
-        if (inode->i_nlink >= EXOFS_LINK_MAX)
-                return -EMLINK;
-
         inode->i_ctime = CURRENT_TIME;
         inode_inc_link_count(inode);
         ihold(inode);
@@ -156,10 +153,7 @@ static int exofs_link(struct dentry *old_dentry, struct inode *dir,
 static int exofs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 {
         struct inode *inode;
-        int err = -EMLINK;
-
-        if (dir->i_nlink >= EXOFS_LINK_MAX)
-                goto out;
+        int err;
 
         inode_inc_link_count(dir);
 
@@ -275,11 +269,6 @@ static int exofs_rename(struct inode *old_dir, struct dentry *old_dentry,
                 if (err)
                         goto out_dir;
         } else {
-                if (dir_de) {
-                        err = -EMLINK;
-                        if (new_dir->i_nlink >= EXOFS_LINK_MAX)
-                                goto out_dir;
-                }
                 err = exofs_add_link(new_dentry, old_inode);
                 if (err)
                         goto out_dir;
diff --git a/fs/exofs/super.c b/fs/exofs/super.c
index d22cd168c6ee..6cafcadfc3c8 100644
--- a/fs/exofs/super.c
+++ b/fs/exofs/super.c
@@ -754,6 +754,7 @@ static int exofs_fill_super(struct super_block *sb, void *data, int silent)
         sb->s_blocksize = EXOFS_BLKSIZE;
         sb->s_blocksize_bits = EXOFS_BLKSHIFT;
         sb->s_maxbytes = MAX_LFS_FILESIZE;
+        sb->s_max_links = EXOFS_LINK_MAX;
         atomic_set(&sbi->s_curr_pending, 0);
         sb->s_bdev = NULL;
         sb->s_dev = 0;