include/linux/vs_cowbl.h

   1 #ifndef _VS_COWBL_H
   2 #define _VS_COWBL_H
   3
   4 #include <linux/fs.h>
   5 #include <linux/dcache.h>
   6 #include <linux/namei.h>
   7
   8 extern struct dentry *cow_break_link(const char *pathname);
   9
  10 static inline int cow_check_and_break(struct nameidata *nd)
  11 {
  12         struct inode *inode = nd->dentry->d_inode;
  13         int error = 0;
  14         if (IS_RDONLY(inode) || MNT_IS_RDONLY(nd->mnt))
  15                 return -EROFS;
  16         if (IS_COW(inode)) {
  17                 if (IS_COW_LINK(inode)) {
  18                         struct dentry *new_dentry, *old_dentry = nd->dentry;
  19                         char *path, *buf;
  20
  21                         buf = kmalloc(PATH_MAX, GFP_KERNEL);
  22                         if (!buf) {
  23                                 return -ENOMEM;
  24                         }
  25                         path = d_path(nd->dentry, nd->mnt, buf, PATH_MAX);
  26                         new_dentry = cow_break_link(path);
  27                         kfree(buf);
  28                         if (!IS_ERR(new_dentry)) {
  29                                 nd->dentry = new_dentry;
  30                                 dput(old_dentry);
  31                         } else
  32                                 error = PTR_ERR(new_dentry);
  33                 } else {
  34                         inode->i_flags &= ~(S_IUNLINK|S_IMMUTABLE);
  35                         inode->i_ctime = CURRENT_TIME;
  36                         mark_inode_dirty(inode);
  37                 }
  38         }
  39         return error;
  40 }
  41
  42 #else
  43 #warning duplicate inclusion
  44 #endif