/*
   * Directory operations for Coda filesystem
   * Original version: (C) 1996 P. Braam and M. Callahan
   * Rewritten for Linux 2.1. (C) 1997 Carnegie Mellon University
   * 
   * Carnegie Mellon encourages users to contribute improvements to
   * the Coda project. Contact Peter Braam (coda@cs.cmu.edu).
   */
  
  #include <linux/types.h>
  #include <linux/kernel.h>
  #include <linux/time.h>
  #include <linux/fs.h>

  #include <linux/slab.h>

  #include <linux/file.h>
  #include <linux/stat.h>
  #include <linux/errno.h>
  #include <linux/string.h>

  #include <linux/spinlock.h>

  #include <linux/namei.h>

  
  #include <asm/uaccess.h>
  
  #include <linux/coda.h>

  #include <linux/coda_psdev.h>

  #include "coda_linux.h"
  #include "coda_cache.h"

  #include "coda_int.h"

  /* dir inode-ops */

  static int coda_create(struct inode *dir, struct dentry *new, umode_t mode, struct nameidata *nd);

  static struct dentry *coda_lookup(struct inode *dir, struct dentry *target, struct nameidata *nd);
  static int coda_link(struct dentry *old_dentry, struct inode *dir_inode, 
  		     struct dentry *entry);
  static int coda_unlink(struct inode *dir_inode, struct dentry *entry);
  static int coda_symlink(struct inode *dir_inode, struct dentry *entry,
  			const char *symname);

  static int coda_mkdir(struct inode *dir_inode, struct dentry *entry, umode_t mode);

  static int coda_rmdir(struct inode *dir_inode, struct dentry *entry);
  static int coda_rename(struct inode *old_inode, struct dentry *old_dentry, 
                         struct inode *new_inode, struct dentry *new_dentry);
  
  /* dir file-ops */

  static int coda_readdir(struct file *file, void *buf, filldir_t filldir);

  
  /* dentry ops */
  static int coda_dentry_revalidate(struct dentry *de, struct nameidata *nd);

  static int coda_dentry_delete(const struct dentry *);

  
  /* support routines */

  static int coda_venus_readdir(struct file *coda_file, void *buf,
  			      filldir_t filldir);

  
  /* same as fs/bad_inode.c */
  static int coda_return_EIO(void)
  {
  	return -EIO;
  }
  #define CODA_EIO_ERROR ((void *) (coda_return_EIO))

  const struct dentry_operations coda_dentry_operations =

  {
  	.d_revalidate	= coda_dentry_revalidate,
  	.d_delete	= coda_dentry_delete,
  };

  const struct inode_operations coda_dir_inode_operations =

  {
  	.create		= coda_create,
  	.lookup		= coda_lookup,
  	.link		= coda_link,
  	.unlink		= coda_unlink,
  	.symlink	= coda_symlink,
  	.mkdir		= coda_mkdir,
  	.rmdir		= coda_rmdir,
  	.mknod		= CODA_EIO_ERROR,
  	.rename		= coda_rename,
  	.permission	= coda_permission,
  	.getattr	= coda_getattr,
  	.setattr	= coda_setattr,
  };

  const struct file_operations coda_dir_operations = {

  	.llseek		= generic_file_llseek,
  	.read		= generic_read_dir,
  	.readdir	= coda_readdir,
  	.open		= coda_open,

  	.release	= coda_release,
  	.fsync		= coda_fsync,
  };
  
  
  /* inode operations for directories */
  /* access routines: lookup, readlink, permission */
  static struct dentry *coda_lookup(struct inode *dir, struct dentry *entry, struct nameidata *nd)
  {

  	struct super_block *sb = dir->i_sb;

  	const char *name = entry->d_name.name;
  	size_t length = entry->d_name.len;

  	struct inode *inode;
  	int type = 0;

  
  	if (length > CODA_MAXNAMLEN) {
  		printk(KERN_ERR "name too long: lookup, %s (%*s)
  ",

  		       coda_i2s(dir), (int)length, name);
  		return ERR_PTR(-ENAMETOOLONG);
  	}

  	/* control object, create inode on the fly */
  	if (coda_isroot(dir) && coda_iscontrol(name, length)) {

  		inode = coda_cnode_makectl(sb);

  		type = CODA_NOCACHE;

  	} else {
  		struct CodaFid fid = { { 0, } };
  		int error = venus_lookup(sb, coda_i2f(dir), name, length,
  				     &type, &fid);
  		inode = !error ? coda_cnode_make(&fid, sb) : ERR_PTR(error);

  	}

  	if (!IS_ERR(inode) && (type & CODA_NOCACHE))

  		coda_flag_inode(inode, C_VATTR | C_PURGE);

  	if (inode == ERR_PTR(-ENOENT))
  		inode = NULL;

  	return d_splice_alias(inode, entry);

  }

  int coda_permission(struct inode *inode, int mask)

  {

  	int error;

  	if (mask & MAY_NOT_BLOCK)

  		return -ECHILD;

  	mask &= MAY_READ | MAY_WRITE | MAY_EXEC;

   
  	if (!mask)

  		return 0;

  	if ((mask & MAY_EXEC) && !execute_ok(inode))
  		return -EACCES;

  	if (coda_cache_check(inode, mask))

  		return 0;

  	error = venus_access(inode->i_sb, coda_i2f(inode), mask);

      
  	if (!error)
  		coda_cache_enter(inode, mask);

  	return error;

  }

  static inline void coda_dir_update_mtime(struct inode *dir)

  {
  #ifdef REQUERY_VENUS_FOR_MTIME
  	/* invalidate the directory cnode's attributes so we refetch the
  	 * attributes from venus next time the inode is referenced */
  	coda_flag_inode(dir, C_VATTR);
  #else
  	/* optimistically we can also act as if our nose bleeds. The

  	 * granularity of the mtime is coarse anyways so we might actually be
  	 * right most of the time. Note: we only do this for directories. */

  	dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
  #endif

  }
  
  /* we have to wrap inc_nlink/drop_nlink because sometimes userspace uses a
   * trick to fool GNU find's optimizations. If we can't be sure of the link
   * (because of volume mount points) we set i_nlink to 1 which forces find
   * to consider every child as a possible directory. We should also never
   * see an increment or decrement for deleted directories where i_nlink == 0 */
  static inline void coda_dir_inc_nlink(struct inode *dir)
  {
  	if (dir->i_nlink >= 2)
  		inc_nlink(dir);
  }
  
  static inline void coda_dir_drop_nlink(struct inode *dir)
  {
  	if (dir->i_nlink > 2)
  		drop_nlink(dir);

  }
  
  /* creation routines: create, mknod, mkdir, link, symlink */

  static int coda_create(struct inode *dir, struct dentry *de, umode_t mode, struct nameidata *nd)

  {

  	int error;

  	const char *name=de->d_name.name;
  	int length=de->d_name.len;
  	struct inode *inode;
  	struct CodaFid newfid;
  	struct coda_vattr attrs;

  	if (coda_isroot(dir) && coda_iscontrol(name, length))

  		return -EPERM;

  
  	error = venus_create(dir->i_sb, coda_i2f(dir), name, length, 
  				0, mode, &newfid, &attrs);

  	if (error)
  		goto err_out;

  
  	inode = coda_iget(dir->i_sb, &newfid, &attrs);

  	if (IS_ERR(inode)) {
  		error = PTR_ERR(inode);
  		goto err_out;

  	}
  
  	/* invalidate the directory cnode's attributes */

  	coda_dir_update_mtime(dir);

  	d_instantiate(de, inode);

  	return 0;

  err_out:
  	d_drop(de);
  	return error;

  }

  static int coda_mkdir(struct inode *dir, struct dentry *de, umode_t mode)

  {
  	struct inode *inode;
  	struct coda_vattr attrs;
  	const char *name = de->d_name.name;
  	int len = de->d_name.len;
  	int error;
  	struct CodaFid newfid;

  	if (coda_isroot(dir) && coda_iscontrol(name, len))

  		return -EPERM;

  
  	attrs.va_mode = mode;
  	error = venus_mkdir(dir->i_sb, coda_i2f(dir), 
  			       name, len, &newfid, &attrs);

  	if (error)
  		goto err_out;

           
  	inode = coda_iget(dir->i_sb, &newfid, &attrs);

  	if (IS_ERR(inode)) {
  		error = PTR_ERR(inode);
  		goto err_out;

  	}

  	/* invalidate the directory cnode's attributes */

  	coda_dir_inc_nlink(dir);
  	coda_dir_update_mtime(dir);

  	d_instantiate(de, inode);

  	return 0;

  err_out:
  	d_drop(de);
  	return error;

  }
  
  /* try to make de an entry in dir_inodde linked to source_de */ 
  static int coda_link(struct dentry *source_de, struct inode *dir_inode, 
  	  struct dentry *de)
  {
  	struct inode *inode = source_de->d_inode;
          const char * name = de->d_name.name;
  	int len = de->d_name.len;
  	int error;

  	if (coda_isroot(dir_inode) && coda_iscontrol(name, len))

  		return -EPERM;

  
  	error = venus_link(dir_inode->i_sb, coda_i2f(inode),
  			   coda_i2f(dir_inode), (const char *)name, len);

  	if (error) {

  		d_drop(de);

  		return error;

  	}

  	coda_dir_update_mtime(dir_inode);

  	ihold(inode);

  	d_instantiate(de, inode);

  	inc_nlink(inode);

  	return 0;

  }
  
  
  static int coda_symlink(struct inode *dir_inode, struct dentry *de,
  			const char *symname)
  {

  	const char *name = de->d_name.name;

  	int len = de->d_name.len;
  	int symlen;

  	int error;

  	if (coda_isroot(dir_inode) && coda_iscontrol(name, len))

  		return -EPERM;

  
  	symlen = strlen(symname);

  	if (symlen > CODA_MAXPATHLEN)

  		return -ENAMETOOLONG;

  
  	/*
  	 * This entry is now negative. Since we do not create

  	 * an inode for the entry we have to drop it.

  	 */
  	d_drop(de);

  	error = venus_symlink(dir_inode->i_sb, coda_i2f(dir_inode), name, len,

  			      symname, symlen);
  
  	/* mtime is no good anymore */

  	if (!error)

  		coda_dir_update_mtime(dir_inode);

  	return error;

  }
  
  /* destruction routines: unlink, rmdir */

  static int coda_unlink(struct inode *dir, struct dentry *de)

  {
          int error;
  	const char *name = de->d_name.name;
  	int len = de->d_name.len;

  	error = venus_remove(dir->i_sb, coda_i2f(dir), name, len);

  	if (error)

  		return error;

  	coda_dir_update_mtime(dir);

  	drop_nlink(de->d_inode);

  	return 0;

  }

  static int coda_rmdir(struct inode *dir, struct dentry *de)

  {
  	const char *name = de->d_name.name;
  	int len = de->d_name.len;

  	int error;

  	error = venus_rmdir(dir->i_sb, coda_i2f(dir), name, len);

  	if (!error) {
  		/* VFS may delete the child */
  		if (de->d_inode)

  			clear_nlink(de->d_inode);

  		/* fix the link count of the parent */
  		coda_dir_drop_nlink(dir);
  		coda_dir_update_mtime(dir);

  	}

  	return error;

  }
  
  /* rename */

  static int coda_rename(struct inode *old_dir, struct dentry *old_dentry,

  		       struct inode *new_dir, struct dentry *new_dentry)
  {

  	const char *old_name = old_dentry->d_name.name;
  	const char *new_name = new_dentry->d_name.name;

  	int old_length = old_dentry->d_name.len;
  	int new_length = new_dentry->d_name.len;

  	int error;

  	error = venus_rename(old_dir->i_sb, coda_i2f(old_dir),
  			     coda_i2f(new_dir), old_length, new_length,

  			     (const char *) old_name, (const char *)new_name);

  	if (!error) {
  		if (new_dentry->d_inode) {
  			if (S_ISDIR(new_dentry->d_inode->i_mode)) {

  				coda_dir_drop_nlink(old_dir);
  				coda_dir_inc_nlink(new_dir);
  			}
  			coda_dir_update_mtime(old_dir);
  			coda_dir_update_mtime(new_dir);

  			coda_flag_inode(new_dentry->d_inode, C_VATTR);
  		} else {
  			coda_flag_inode(old_dir, C_VATTR);
  			coda_flag_inode(new_dir, C_VATTR);

  		}

  	}

  	return error;
  }
  
  
  /* file operations for directories */

  static int coda_readdir(struct file *coda_file, void *buf, filldir_t filldir)

  {

  	struct coda_file_info *cfi;
  	struct file *host_file;

  	int ret;
  
  	cfi = CODA_FTOC(coda_file);
  	BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
  	host_file = cfi->cfi_container;

  	if (!host_file->f_op)
  		return -ENOTDIR;
  
  	if (host_file->f_op->readdir)
  	{
  		/* potemkin case: we were handed a directory inode.
  		 * We can't use vfs_readdir because we have to keep the file
  		 * position in sync between the coda_file and the host_file.
  		 * and as such we need grab the inode mutex. */
  		struct inode *host_inode = host_file->f_path.dentry->d_inode;
  
  		mutex_lock(&host_inode->i_mutex);
  		host_file->f_pos = coda_file->f_pos;

  
  		ret = -ENOENT;
  		if (!IS_DEADDIR(host_inode)) {

  			ret = host_file->f_op->readdir(host_file, buf, filldir);

  			file_accessed(host_file);
  		}

  
  		coda_file->f_pos = host_file->f_pos;
  		mutex_unlock(&host_inode->i_mutex);

  	}

  	else /* Venus: we must read Venus dirents from a file */
  		ret = coda_venus_readdir(coda_file, buf, filldir);

  
  	return ret;
  }
  
  static inline unsigned int CDT2DT(unsigned char cdt)
  {
  	unsigned int dt;
  
  	switch(cdt) {
  	case CDT_UNKNOWN: dt = DT_UNKNOWN; break;
  	case CDT_FIFO:	  dt = DT_FIFO;    break;
  	case CDT_CHR:	  dt = DT_CHR;     break;
  	case CDT_DIR:	  dt = DT_DIR;     break;
  	case CDT_BLK:	  dt = DT_BLK;     break;
  	case CDT_REG:	  dt = DT_REG;     break;
  	case CDT_LNK:	  dt = DT_LNK;     break;
  	case CDT_SOCK:	  dt = DT_SOCK;    break;
  	case CDT_WHT:	  dt = DT_WHT;     break;
  	default:	  dt = DT_UNKNOWN; break;
  	}
  	return dt;
  }
  
  /* support routines */

  static int coda_venus_readdir(struct file *coda_file, void *buf,
  			      filldir_t filldir)

  {
  	int result = 0; /* # of entries returned */

  	struct coda_file_info *cfi;
  	struct coda_inode_info *cii;
  	struct file *host_file;
  	struct dentry *de;

  	struct venus_dirent *vdir;

  	unsigned long vdir_size = offsetof(struct venus_dirent, d_name);

  	unsigned int type;
  	struct qstr name;
  	ino_t ino;

  	int ret;
  
  	cfi = CODA_FTOC(coda_file);
  	BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
  	host_file = cfi->cfi_container;
  
  	de = coda_file->f_path.dentry;
  	cii = ITOC(de->d_inode);

  	vdir = kmalloc(sizeof(*vdir), GFP_KERNEL);

  	if (!vdir) return -ENOMEM;

  	if (coda_file->f_pos == 0) {

  		ret = filldir(buf, ".", 1, 0, de->d_inode->i_ino, DT_DIR);

  		if (ret < 0)
  			goto out;

  		result++;

  		coda_file->f_pos++;

  	}
  	if (coda_file->f_pos == 1) {

  		ret = filldir(buf, "..", 2, 1, parent_ino(de), DT_DIR);

  		if (ret < 0)
  			goto out;

  		result++;

  		coda_file->f_pos++;

  	}

  	while (1) {
  		/* read entries from the directory file */

  		ret = kernel_read(host_file, coda_file->f_pos - 2, (char *)vdir,

  				  sizeof(*vdir));
  		if (ret < 0) {

  			printk(KERN_ERR "coda readdir: read dir %s failed %d
  ",
  			       coda_f2s(&cii->c_fid), ret);

  			break;
  		}
  		if (ret == 0) break; /* end of directory file reached */
  
  		/* catch truncated reads */
  		if (ret < vdir_size || ret < vdir_size + vdir->d_namlen) {

  			printk(KERN_ERR "coda readdir: short read on %s
  ",
  			       coda_f2s(&cii->c_fid));

  			ret = -EBADF;
  			break;
  		}
  		/* validate whether the directory file actually makes sense */
  		if (vdir->d_reclen < vdir_size + vdir->d_namlen) {

  			printk(KERN_ERR "coda readdir: invalid dir %s
  ",
  			       coda_f2s(&cii->c_fid));

  			ret = -EBADF;
  			break;
  		}
  
  		name.len = vdir->d_namlen;
  		name.name = vdir->d_name;
  
  		/* Make sure we skip '.' and '..', we already got those */
  		if (name.name[0] == '.' && (name.len == 1 ||
  		    (vdir->d_name[1] == '.' && name.len == 2)))
  			vdir->d_fileno = name.len = 0;
  
  		/* skip null entries */
  		if (vdir->d_fileno && name.len) {
  			/* try to look up this entry in the dcache, that way
  			 * userspace doesn't have to worry about breaking
  			 * getcwd by having mismatched inode numbers for
  			 * internal volume mountpoints. */

  			ino = find_inode_number(de, &name);

  			if (!ino) ino = vdir->d_fileno;
  
  			type = CDT2DT(vdir->d_type);

  			ret = filldir(buf, name.name, name.len,
  				      coda_file->f_pos, ino, type);

  			/* failure means no space for filling in this round */
  			if (ret < 0) break;
  			result++;
  		}
  		/* we'll always have progress because d_reclen is unsigned and
  		 * we've already established it is non-zero. */

  		coda_file->f_pos += vdir->d_reclen;
  	}

  out:

  	kfree(vdir);
  	return result ? result : ret;
  }
  
  /* called when a cache lookup succeeds */
  static int coda_dentry_revalidate(struct dentry *de, struct nameidata *nd)
  {

  	struct inode *inode;

  	struct coda_inode_info *cii;

  	if (nd->flags & LOOKUP_RCU)
  		return -ECHILD;
  
  	inode = de->d_inode;

  	if (!inode || coda_isroot(inode))

  		goto out;
  	if (is_bad_inode(inode))
  		goto bad;
  
  	cii = ITOC(de->d_inode);
  	if (!(cii->c_flags & (C_PURGE | C_FLUSH)))
  		goto out;
  
  	shrink_dcache_parent(de);
  
  	/* propagate for a flush */
  	if (cii->c_flags & C_FLUSH) 
  		coda_flag_inode_children(inode, C_FLUSH);

  	if (de->d_count > 1)

  		/* pretend it's valid, but don't change the flags */
  		goto out;
  
  	/* clear the flags. */

  	spin_lock(&cii->c_lock);

  	cii->c_flags &= ~(C_VATTR | C_PURGE | C_FLUSH);

  	spin_unlock(&cii->c_lock);

  bad:

  	return 0;
  out:

  	return 1;
  }
  
  /*
   * This is the callback from dput() when d_count is going to 0.
   * We use this to unhash dentries with bad inodes.
   */

  static int coda_dentry_delete(const struct dentry * dentry)

  {
  	int flags;
  
  	if (!dentry->d_inode) 
  		return 0;
  
  	flags = (ITOC(dentry->d_inode)->c_flags) & C_PURGE;
  	if (is_bad_inode(dentry->d_inode) || flags) {
  		return 1;
  	}
  	return 0;
  }
  
  
  
  /*
   * This is called when we want to check if the inode has
   * changed on the server.  Coda makes this easy since the
   * cache manager Venus issues a downcall to the kernel when this 
   * happens 
   */
  int coda_revalidate_inode(struct dentry *dentry)
  {
  	struct coda_vattr attr;

  	int error;

  	int old_mode;
  	ino_t old_ino;
  	struct inode *inode = dentry->d_inode;
  	struct coda_inode_info *cii = ITOC(inode);

  	if (!cii->c_flags)
  		return 0;

  
  	if (cii->c_flags & (C_VATTR | C_PURGE | C_FLUSH)) {
  		error = venus_getattr(inode->i_sb, &(cii->c_fid), &attr);

  		if (error)
  			return -EIO;

  
  		/* this inode may be lost if:
  		   - it's ino changed 
  		   - type changes must be permitted for repair and
  		   missing mount points.
  		*/
  		old_mode = inode->i_mode;
  		old_ino = inode->i_ino;
  		coda_vattr_to_iattr(inode, &attr);
  
  		if ((old_mode & S_IFMT) != (inode->i_mode & S_IFMT)) {
  			printk("Coda: inode %ld, fid %s changed type!
  ",
  			       inode->i_ino, coda_f2s(&(cii->c_fid)));
  		}
  
  		/* the following can happen when a local fid is replaced 
  		   with a global one, here we lose and declare the inode bad */
  		if (inode->i_ino != old_ino)

  			return -EIO;

  		
  		coda_flag_inode_children(inode, C_FLUSH);

  
  		spin_lock(&cii->c_lock);

  		cii->c_flags &= ~(C_VATTR | C_PURGE | C_FLUSH);

  		spin_unlock(&cii->c_lock);

  	}

  	return 0;

  }