path: root/fs/ntfs/attrib.c

/**
 * attrib.c - NTFS attribute operations.  Part of the Linux-NTFS project.
 *
 * Copyright (c) 2001-2004 Anton Altaparmakov
 * Copyright (c) 2002 Richard Russon
 *
 * This program/include file is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program/include file is distributed in the hope that it will be
 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program (in the main directory of the Linux-NTFS
 * distribution in the file COPYING); if not, write to the Free Software
 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <linux/buffer_head.h>

#include "attrib.h"
#include "debug.h"
#include "layout.h"
#include "mft.h"
#include "ntfs.h"
#include "types.h"

/**
 * ntfs_map_runlist - map (a part of) a runlist of an ntfs inode
 * @ni:		ntfs inode for which to map (part of) a runlist
 * @vcn:	map runlist part containing this vcn
 *
 * Map the part of a runlist containing the @vcn of the ntfs inode @ni.
 *
 * Return 0 on success and -errno on error.
 *
 * Locking: - The runlist must be unlocked on entry and is unlocked on return.
 *	    - This function takes the lock for writing and modifies the runlist.
 */
int ntfs_map_runlist(ntfs_inode *ni, VCN vcn)
{
	ntfs_inode *base_ni;
	ntfs_attr_search_ctx *ctx;
	MFT_RECORD *mrec;
	int err = 0;

	ntfs_debug("Mapping runlist part containing vcn 0x%llx.",
			(unsigned long long)vcn);

	if (!NInoAttr(ni))
		base_ni = ni;
	else
		base_ni = ni->ext.base_ntfs_ino;

	mrec = map_mft_record(base_ni);
	if (IS_ERR(mrec))
		return PTR_ERR(mrec);
	ctx = ntfs_attr_get_search_ctx(base_ni, mrec);
	if (unlikely(!ctx)) {
		err = -ENOMEM;
		goto err_out;
	}
	err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
			CASE_SENSITIVE, vcn, NULL, 0, ctx);
	if (unlikely(err))
		goto put_err_out;

	down_write(&ni->runlist.lock);
	/* Make sure someone else didn't do the work while we were sleeping. */
	if (likely(ntfs_rl_vcn_to_lcn(ni->runlist.rl, vcn) <=
			LCN_RL_NOT_MAPPED)) {
		runlist_element *rl;

		rl = ntfs_mapping_pairs_decompress(ni->vol, ctx->attr,
				ni->runlist.rl);
		if (IS_ERR(rl))
			err = PTR_ERR(rl);
		else
			ni->runlist.rl = rl;
	}
	up_write(&ni->runlist.lock);

put_err_out:
	ntfs_attr_put_search_ctx(ctx);
err_out:
	unmap_mft_record(base_ni);
	return err;
}

/**
 * ntfs_find_vcn - find a vcn in the runlist described by an ntfs inode
 * @ni:		ntfs inode describing the runlist to search
 * @vcn:	vcn to find
 * @need_write:	if false, lock for reading and if true, lock for writing
 *
 * Find the virtual cluster number @vcn in the runlist described by the ntfs
 * inode @ni and return the address of the runlist element containing the @vcn.
 * The runlist is left locked and the caller has to unlock it.  If @need_write
 * is true, the runlist is locked for writing and if @need_write is false, the
 * runlist is locked for reading.  In the error case, the runlist is not left
 * locked.
 *
 * Note you need to distinguish between the lcn of the returned runlist element
 * being >= 0 and LCN_HOLE.  In the later case you have to return zeroes on
 * read and allocate clusters on write.
 *
 * Return the runlist element containing the @vcn on success and
 * ERR_PTR(-errno) on error.  You need to test the return value with IS_ERR()
 * to decide if the return is success or failure and PTR_ERR() to get to the
 * error code if IS_ERR() is true.
 *
 * The possible error return codes are:
 *	-ENOENT - No such vcn in the runlist, i.e. @vcn is out of bounds.
 *	-ENOMEM - Not enough memory to map runlist.
 *	-EIO	- Critical error (runlist/file is corrupt, i/o error, etc).
 *
 * Locking: - The runlist must be unlocked on entry.
 *	    - On failing return, the runlist is unlocked.
 *	    - On successful return, the runlist is locked.  If @need_write us