/*
   * Copyright (c) 2002 Red Hat, Inc. All rights reserved.
   *
   * This software may be freely redistributed under the terms of the
   * GNU General Public License.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
   *

   * Authors: David Woodhouse <dwmw2@infradead.org>

   *          David Howells <dhowells@redhat.com>
   *
   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/init.h>

  #include <linux/fs.h>
  #include <linux/pagemap.h>

  #include <linux/sched.h>

  #include <linux/mount.h>
  #include <linux/namei.h>

  #include "internal.h"
  
  struct afs_iget_data {
  	struct afs_fid		fid;
  	struct afs_volume	*volume;	/* volume on which resides */
  };

  static const struct inode_operations afs_symlink_inode_operations = {
  	.get_link	= page_get_link,
  	.listxattr	= afs_listxattr,
  };

  /*
   * map the AFS file status to the inode member variables
   */

  static int afs_inode_map_status(struct afs_vnode *vnode, struct key *key)

  {
  	struct inode *inode = AFS_VNODE_TO_I(vnode);

  	_debug("FS: ft=%d lk=%d sz=%llu ver=%Lu mod=%hu",

  	       vnode->status.type,
  	       vnode->status.nlink,

  	       (unsigned long long) vnode->status.size,

  	       vnode->status.data_version,

  	       vnode->status.mode);
  
  	switch (vnode->status.type) {
  	case AFS_FTYPE_FILE:
  		inode->i_mode	= S_IFREG | vnode->status.mode;
  		inode->i_op	= &afs_file_inode_operations;

  		inode->i_fop	= &afs_file_operations;

  		break;
  	case AFS_FTYPE_DIR:
  		inode->i_mode	= S_IFDIR | vnode->status.mode;
  		inode->i_op	= &afs_dir_inode_operations;
  		inode->i_fop	= &afs_dir_file_operations;
  		break;
  	case AFS_FTYPE_SYMLINK:

  		/* Symlinks with a mode of 0644 are actually mountpoints. */
  		if ((vnode->status.mode & 0777) == 0644) {
  			inode->i_flags |= S_AUTOMOUNT;
  
  			spin_lock(&vnode->lock);
  			set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags);
  			spin_unlock(&vnode->lock);
  
  			inode->i_mode	= S_IFDIR | 0555;
  			inode->i_op	= &afs_mntpt_inode_operations;
  			inode->i_fop	= &afs_mntpt_file_operations;
  		} else {
  			inode->i_mode	= S_IFLNK | vnode->status.mode;

  			inode->i_op	= &afs_symlink_inode_operations;

  		}

  		inode_nohighmem(inode);

  		break;
  	default:
  		printk("kAFS: AFS vnode with undefined type
  ");
  		return -EBADMSG;
  	}

  #ifdef CONFIG_AFS_FSCACHE
  	if (vnode->status.size != inode->i_size)
  		fscache_attr_changed(vnode->cache);
  #endif

  	set_nlink(inode, vnode->status.nlink);

  	inode->i_uid		= vnode->status.owner;

  	inode->i_gid            = vnode->status.group;

  	inode->i_size		= vnode->status.size;

  	inode->i_ctime.tv_sec	= vnode->status.mtime_client;

  	inode->i_ctime.tv_nsec	= 0;
  	inode->i_atime		= inode->i_mtime = inode->i_ctime;

  	inode->i_blocks		= 0;

  	inode->i_generation	= vnode->fid.unique;
  	inode->i_version	= vnode->status.data_version;

  	inode->i_mapping->a_ops	= &afs_fs_aops;

  	return 0;

  }

  /*

   * iget5() comparator
   */
  static int afs_iget5_test(struct inode *inode, void *opaque)
  {
  	struct afs_iget_data *data = opaque;
  
  	return inode->i_ino == data->fid.vnode &&

  		inode->i_generation == data->fid.unique;

  }

  /*

   * iget5() comparator for inode created by autocell operations
   *
   * These pseudo inodes don't match anything.
   */
  static int afs_iget5_autocell_test(struct inode *inode, void *opaque)
  {
  	return 0;
  }
  
  /*

   * iget5() inode initialiser
   */
  static int afs_iget5_set(struct inode *inode, void *opaque)
  {
  	struct afs_iget_data *data = opaque;
  	struct afs_vnode *vnode = AFS_FS_I(inode);
  
  	inode->i_ino = data->fid.vnode;

  	inode->i_generation = data->fid.unique;

  	vnode->fid = data->fid;
  	vnode->volume = data->volume;
  
  	return 0;

  }

  /*

   * inode retrieval for autocell
   */
  struct inode *afs_iget_autocell(struct inode *dir, const char *dev_name,
  				int namesz, struct key *key)
  {
  	struct afs_iget_data data;
  	struct afs_super_info *as;
  	struct afs_vnode *vnode;
  	struct super_block *sb;
  	struct inode *inode;
  	static atomic_t afs_autocell_ino;
  
  	_enter("{%x:%u},%*.*s,",
  	       AFS_FS_I(dir)->fid.vid, AFS_FS_I(dir)->fid.vnode,
  	       namesz, namesz, dev_name ?: "");
  
  	sb = dir->i_sb;
  	as = sb->s_fs_info;
  	data.volume = as->volume;
  	data.fid.vid = as->volume->vid;
  	data.fid.unique = 0;
  	data.fid.vnode = 0;
  
  	inode = iget5_locked(sb, atomic_inc_return(&afs_autocell_ino),
  			     afs_iget5_autocell_test, afs_iget5_set,
  			     &data);
  	if (!inode) {
  		_leave(" = -ENOMEM");
  		return ERR_PTR(-ENOMEM);
  	}
  
  	_debug("GOT INODE %p { ino=%lu, vl=%x, vn=%x, u=%x }",
  	       inode, inode->i_ino, data.fid.vid, data.fid.vnode,
  	       data.fid.unique);
  
  	vnode = AFS_FS_I(inode);
  
  	/* there shouldn't be an existing inode */
  	BUG_ON(!(inode->i_state & I_NEW));
  
  	inode->i_size		= 0;
  	inode->i_mode		= S_IFDIR | S_IRUGO | S_IXUGO;
  	inode->i_op		= &afs_autocell_inode_operations;

  	set_nlink(inode, 2);

  	inode->i_uid		= GLOBAL_ROOT_UID;
  	inode->i_gid		= GLOBAL_ROOT_GID;

  	inode->i_ctime.tv_sec	= get_seconds();
  	inode->i_ctime.tv_nsec	= 0;
  	inode->i_atime		= inode->i_mtime = inode->i_ctime;
  	inode->i_blocks		= 0;
  	inode->i_version	= 0;
  	inode->i_generation	= 0;
  
  	set_bit(AFS_VNODE_PSEUDODIR, &vnode->flags);

  	set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags);
  	inode->i_flags |= S_AUTOMOUNT | S_NOATIME;

  	unlock_new_inode(inode);
  	_leave(" = %p", inode);
  	return inode;
  }
  
  /*

   * inode retrieval
   */

  struct inode *afs_iget(struct super_block *sb, struct key *key,
  		       struct afs_fid *fid, struct afs_file_status *status,
  		       struct afs_callback *cb)

  {
  	struct afs_iget_data data = { .fid = *fid };
  	struct afs_super_info *as;
  	struct afs_vnode *vnode;
  	struct inode *inode;
  	int ret;

  	_enter(",{%x:%u.%u},,", fid->vid, fid->vnode, fid->unique);

  
  	as = sb->s_fs_info;
  	data.volume = as->volume;
  
  	inode = iget5_locked(sb, fid->vnode, afs_iget5_test, afs_iget5_set,
  			     &data);
  	if (!inode) {
  		_leave(" = -ENOMEM");

  		return ERR_PTR(-ENOMEM);

  	}

  	_debug("GOT INODE %p { vl=%x vn=%x, u=%x }",
  	       inode, fid->vid, fid->vnode, fid->unique);

  	vnode = AFS_FS_I(inode);
  
  	/* deal with an existing inode */
  	if (!(inode->i_state & I_NEW)) {

  		_leave(" = %p", inode);
  		return inode;

  	}

  	if (!status) {
  		/* it's a remotely extant inode */
  		set_bit(AFS_VNODE_CB_BROKEN, &vnode->flags);
  		ret = afs_vnode_fetch_status(vnode, NULL, key);
  		if (ret < 0)
  			goto bad_inode;
  	} else {
  		/* it's an inode we just created */
  		memcpy(&vnode->status, status, sizeof(vnode->status));
  
  		if (!cb) {
  			/* it's a symlink we just created (the fileserver
  			 * didn't give us a callback) */
  			vnode->cb_version = 0;
  			vnode->cb_expiry = 0;
  			vnode->cb_type = 0;

  			vnode->cb_expires = ktime_get_real_seconds();

  		} else {
  			vnode->cb_version = cb->version;
  			vnode->cb_expiry = cb->expiry;
  			vnode->cb_type = cb->type;

  			vnode->cb_expires = vnode->cb_expiry +
  				ktime_get_real_seconds();

  		}
  	}

  	/* set up caching before mapping the status, as map-status reads the
  	 * first page of symlinks to see if they're really mountpoints */
  	inode->i_size = vnode->status.size;
  #ifdef CONFIG_AFS_FSCACHE
  	vnode->cache = fscache_acquire_cookie(vnode->volume->cache,
  					      &afs_vnode_cache_index_def,

  					      vnode, true);

  #endif

  	ret = afs_inode_map_status(vnode, key);

  	if (ret < 0)

  		goto bad_inode;
  
  	/* success */

  	clear_bit(AFS_VNODE_UNSET, &vnode->flags);

  	inode->i_flags |= S_NOATIME;

  	unlock_new_inode(inode);

  	_leave(" = %p [CB { v=%u t=%u }]", inode, vnode->cb_version, vnode->cb_type);
  	return inode;

  
  	/* failure */

  bad_inode:

  #ifdef CONFIG_AFS_FSCACHE
  	fscache_relinquish_cookie(vnode->cache, 0);
  	vnode->cache = NULL;
  #endif

  	iget_failed(inode);

  	_leave(" = %d [bad]", ret);

  	return ERR_PTR(ret);

  }

  /*

   * mark the data attached to an inode as obsolete due to a write on the server
   * - might also want to ditch all the outstanding writes and dirty pages
   */
  void afs_zap_data(struct afs_vnode *vnode)
  {

  	_enter("{%x:%u}", vnode->fid.vid, vnode->fid.vnode);

  
  	/* nuke all the non-dirty pages that aren't locked, mapped or being

  	 * written back in a regular file and completely discard the pages in a
  	 * directory or symlink */
  	if (S_ISREG(vnode->vfs_inode.i_mode))
  		invalidate_remote_inode(&vnode->vfs_inode);
  	else
  		invalidate_inode_pages2(vnode->vfs_inode.i_mapping);

  }
  
  /*

   * validate a vnode/inode
   * - there are several things we need to check
   *   - parent dir data changes (rm, rmdir, rename, mkdir, create, link,
   *     symlink)
   *   - parent dir metadata changed (security changes)
   *   - dentry data changed (write, truncate)
   *   - dentry metadata changed (security changes)
   */
  int afs_validate(struct afs_vnode *vnode, struct key *key)
  {
  	int ret;
  
  	_enter("{v={%x:%u} fl=%lx},%x",
  	       vnode->fid.vid, vnode->fid.vnode, vnode->flags,
  	       key_serial(key));
  
  	if (vnode->cb_promised &&
  	    !test_bit(AFS_VNODE_CB_BROKEN, &vnode->flags) &&
  	    !test_bit(AFS_VNODE_MODIFIED, &vnode->flags) &&
  	    !test_bit(AFS_VNODE_ZAP_DATA, &vnode->flags)) {

  		if (vnode->cb_expires < ktime_get_real_seconds() + 10) {

  			_debug("callback expired");
  			set_bit(AFS_VNODE_CB_BROKEN, &vnode->flags);
  		} else {
  			goto valid;
  		}
  	}
  
  	if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
  		goto valid;
  
  	mutex_lock(&vnode->validate_lock);
  
  	/* if the promise has expired, we need to check the server again to get
  	 * a new promise - note that if the (parent) directory's metadata was
  	 * changed then the security may be different and we may no longer have
  	 * access */
  	if (!vnode->cb_promised ||
  	    test_bit(AFS_VNODE_CB_BROKEN, &vnode->flags)) {
  		_debug("not promised");
  		ret = afs_vnode_fetch_status(vnode, NULL, key);
  		if (ret < 0)
  			goto error_unlock;
  		_debug("new promise [fl=%lx]", vnode->flags);
  	}
  
  	if (test_bit(AFS_VNODE_DELETED, &vnode->flags)) {
  		_debug("file already deleted");
  		ret = -ESTALE;
  		goto error_unlock;
  	}
  
  	/* if the vnode's data version number changed then its contents are
  	 * different */

  	if (test_and_clear_bit(AFS_VNODE_ZAP_DATA, &vnode->flags))
  		afs_zap_data(vnode);

  
  	clear_bit(AFS_VNODE_MODIFIED, &vnode->flags);
  	mutex_unlock(&vnode->validate_lock);
  valid:
  	_leave(" = 0");
  	return 0;
  
  error_unlock:
  	mutex_unlock(&vnode->validate_lock);
  	_leave(" = %d", ret);
  	return ret;
  }
  
  /*

   * read the attributes of an inode
   */

  int afs_getattr(const struct path *path, struct kstat *stat,
  		u32 request_mask, unsigned int query_flags)

  {

  	struct inode *inode = d_inode(path->dentry);

  	_enter("{ ino=%lu v=%u }", inode->i_ino, inode->i_generation);

  	generic_fillattr(inode, stat);

  	return 0;

  }

  /*

   * discard an AFS inode
   */
  int afs_drop_inode(struct inode *inode)
  {
  	_enter("");
  
  	if (test_bit(AFS_VNODE_PSEUDODIR, &AFS_FS_I(inode)->flags))
  		return generic_delete_inode(inode);
  	else
  		return generic_drop_inode(inode);
  }
  
  /*

   * clear an AFS inode
   */

  void afs_evict_inode(struct inode *inode)

  {

  	struct afs_permits *permits;

  	struct afs_vnode *vnode;
  
  	vnode = AFS_FS_I(inode);

  	_enter("{%x:%u.%d} v=%u x=%u t=%u }",

  	       vnode->fid.vid,

  	       vnode->fid.vnode,

  	       vnode->fid.unique,

  	       vnode->cb_version,
  	       vnode->cb_expiry,

  	       vnode->cb_type);

  	_debug("CLEAR INODE %p", inode);
  
  	ASSERTCMP(inode->i_ino, ==, vnode->fid.vnode);

  	truncate_inode_pages_final(&inode->i_data);

  	clear_inode(inode);

  	afs_give_up_callback(vnode);
  
  	if (vnode->server) {
  		spin_lock(&vnode->server->fs_lock);
  		rb_erase(&vnode->server_rb, &vnode->server->fs_vnodes);
  		spin_unlock(&vnode->server->fs_lock);
  		afs_put_server(vnode->server);
  		vnode->server = NULL;
  	}

  	ASSERT(list_empty(&vnode->writebacks));

  	ASSERT(!vnode->cb_promised);

  #ifdef CONFIG_AFS_FSCACHE
  	fscache_relinquish_cookie(vnode->cache, 0);

  	vnode->cache = NULL;
  #endif

  	mutex_lock(&vnode->permits_lock);
  	permits = vnode->permits;

  	RCU_INIT_POINTER(vnode->permits, NULL);

  	mutex_unlock(&vnode->permits_lock);
  	if (permits)
  		call_rcu(&permits->rcu, afs_zap_permits);

  	_leave("");

  }

  
  /*
   * set the attributes of an inode
   */
  int afs_setattr(struct dentry *dentry, struct iattr *attr)
  {

  	struct afs_vnode *vnode = AFS_FS_I(d_inode(dentry));

  	struct key *key;
  	int ret;

  	_enter("{%x:%u},{n=%pd},%x",
  	       vnode->fid.vid, vnode->fid.vnode, dentry,

  	       attr->ia_valid);
  
  	if (!(attr->ia_valid & (ATTR_SIZE | ATTR_MODE | ATTR_UID | ATTR_GID |
  				ATTR_MTIME))) {
  		_leave(" = 0 [unsupported]");
  		return 0;
  	}
  
  	/* flush any dirty data outstanding on a regular file */
  	if (S_ISREG(vnode->vfs_inode.i_mode)) {
  		filemap_write_and_wait(vnode->vfs_inode.i_mapping);
  		afs_writeback_all(vnode);
  	}
  
  	if (attr->ia_valid & ATTR_FILE) {
  		key = attr->ia_file->private_data;
  	} else {
  		key = afs_request_key(vnode->volume->cell);
  		if (IS_ERR(key)) {
  			ret = PTR_ERR(key);
  			goto error;
  		}
  	}
  
  	ret = afs_vnode_setattr(vnode, key, attr);
  	if (!(attr->ia_valid & ATTR_FILE))
  		key_put(key);
  
  error:
  	_leave(" = %d", ret);
  	return ret;
  }