attrib.c

linux 内核源代码

	return 0;
}

/**
 * ntfs_attr_make_non_resident - convert a resident to a non-resident attribute
 * @ni:		ntfs inode describing the attribute to convert
 * @data_size:	size of the resident data to copy to the non-resident attribute
 *
 * Convert the resident ntfs attribute described by the ntfs inode @ni to a
 * non-resident one.
 *
 * @data_size must be equal to the attribute value size.  This is needed since
 * we need to know the size before we can map the mft record and our callers
 * always know it.  The reason we cannot simply read the size from the vfs
 * inode i_size is that this is not necessarily uptodate.  This happens when
 * ntfs_attr_make_non_resident() is called in the ->truncate call path(s).
 *
 * Return 0 on success and -errno on error.  The following error return codes
 * are defined:
 *	-EPERM	- The attribute is not allowed to be non-resident.
 *	-ENOMEM	- Not enough memory.
 *	-ENOSPC	- Not enough disk space.
 *	-EINVAL	- Attribute not defined on the volume.
 *	-EIO	- I/o error or other error.
 * Note that -ENOSPC is also returned in the case that there is not enough
 * space in the mft record to do the conversion.  This can happen when the mft
 * record is already very full.  The caller is responsible for trying to make
 * space in the mft record and trying again.  FIXME: Do we need a separate
 * error return code for this kind of -ENOSPC or is it always worth trying
 * again in case the attribute may then fit in a resident state so no need to
 * make it non-resident at all?  Ho-hum...  (AIA)
 *
 * NOTE to self: No changes in the attribute list are required to move from
 *		 a resident to a non-resident attribute.
 *
 * Locking: - The caller must hold i_mutex on the inode.
 */
int ntfs_attr_make_non_resident(ntfs_inode *ni, const u32 data_size)
{
	s64 new_size;
	struct inode *vi = VFS_I(ni);
	ntfs_volume *vol = ni->vol;
	ntfs_inode *base_ni;
	MFT_RECORD *m;
	ATTR_RECORD *a;
	ntfs_attr_search_ctx *ctx;
	struct page *page;
	runlist_element *rl;
	u8 *kaddr;
	unsigned long flags;
	int mp_size, mp_ofs, name_ofs, arec_size, err, err2;
	u32 attr_size;
	u8 old_res_attr_flags;

	/* Check that the attribute is allowed to be non-resident. */
	err = ntfs_attr_can_be_non_resident(vol, ni->type);
	if (unlikely(err)) {
		if (err == -EPERM)
			ntfs_debug("Attribute is not allowed to be "
					"non-resident.");
		else
			ntfs_debug("Attribute not defined on the NTFS "
					"volume!");
		return err;
	}
	/*
	 * FIXME: Compressed and encrypted attributes are not supported when
	 * writing and we should never have gotten here for them.
	 */
	BUG_ON(NInoCompressed(ni));
	BUG_ON(NInoEncrypted(ni));
	/*
	 * The size needs to be aligned to a cluster boundary for allocation
	 * purposes.
	 */
	new_size = (data_size + vol->cluster_size - 1) &
			~(vol->cluster_size - 1);
	if (new_size > 0) {
		/*
		 * Will need the page later and since the page lock nests
		 * outside all ntfs locks, we need to get the page now.
		 */
		page = find_or_create_page(vi->i_mapping, 0,
				mapping_gfp_mask(vi->i_mapping));
		if (unlikely(!page))
			return -ENOMEM;
		/* Start by allocating clusters to hold the attribute value. */
		rl = ntfs_cluster_alloc(vol, 0, new_size >>
				vol->cluster_size_bits, -1, DATA_ZONE, true);
		if (IS_ERR(rl)) {
			err = PTR_ERR(rl);
			ntfs_debug("Failed to allocate cluster%s, error code "
					"%i.", (new_size >>
					vol->cluster_size_bits) > 1 ? "s" : "",
					err);
			goto page_err_out;
		}
	} else {
		rl = NULL;
		page = NULL;
	}
	/* Determine the size of the mapping pairs array. */
	mp_size = ntfs_get_size_for_mapping_pairs(vol, rl, 0, -1);
	if (unlikely(mp_size < 0)) {
		err = mp_size;
		ntfs_debug("Failed to get size for mapping pairs array, error "
				"code %i.", err);
		goto rl_err_out;
	}
	down_write(&ni->runlist.lock);
	if (!NInoAttr(ni))
		base_ni = ni;
	else
		base_ni = ni->ext.base_ntfs_ino;
	m = map_mft_record(base_ni);
	if (IS_ERR(m)) {
		err = PTR_ERR(m);
		m = NULL;
		ctx = NULL;
		goto err_out;
	}
	ctx = ntfs_attr_get_search_ctx(base_ni, m);
	if (unlikely(!ctx)) {
		err = -ENOMEM;
		goto err_out;
	}
	err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
			CASE_SENSITIVE, 0, NULL, 0, ctx);
	if (unlikely(err)) {
		if (err == -ENOENT)
			err = -EIO;
		goto err_out;
	}
	m = ctx->mrec;
	a = ctx->attr;
	BUG_ON(NInoNonResident(ni));
	BUG_ON(a->non_resident);
	/*
	 * Calculate new offsets for the name and the mapping pairs array.
	 */
	if (NInoSparse(ni) || NInoCompressed(ni))
		name_ofs = (offsetof(ATTR_REC,
				data.non_resident.compressed_size) +
				sizeof(a->data.non_resident.compressed_size) +
				7) & ~7;
	else
		name_ofs = (offsetof(ATTR_REC,
				data.non_resident.compressed_size) + 7) & ~7;
	mp_ofs = (name_ofs + a->name_length * sizeof(ntfschar) + 7) & ~7;
	/*
	 * Determine the size of the resident part of the now non-resident
	 * attribute record.
	 */
	arec_size = (mp_ofs + mp_size + 7) & ~7;
	/*
	 * If the page is not uptodate bring it uptodate by copying from the
	 * attribute value.
	 */
	attr_size = le32_to_cpu(a->data.resident.value_length);
	BUG_ON(attr_size != data_size);
	if (page && !PageUptodate(page)) {
		kaddr = kmap_atomic(page, KM_USER0);
		memcpy(kaddr, (u8*)a +
				le16_to_cpu(a->data.resident.value_offset),
				attr_size);
		memset(kaddr + attr_size, 0, PAGE_CACHE_SIZE - attr_size);
		kunmap_atomic(kaddr, KM_USER0);
		flush_dcache_page(page);
		SetPageUptodate(page);
	}
	/* Backup the attribute flag. */
	old_res_attr_flags = a->data.resident.flags;
	/* Resize the resident part of the attribute record. */
	err = ntfs_attr_record_resize(m, a, arec_size);
	if (unlikely(err))
		goto err_out;
	/*
	 * Convert the resident part of the attribute record to describe a
	 * non-resident attribute.
	 */
	a->non_resident = 1;
	/* Move the attribute name if it exists and update the offset. */
	if (a->name_length)
		memmove((u8*)a + name_ofs, (u8*)a + le16_to_cpu(a->name_offset),
				a->name_length * sizeof(ntfschar));
	a->name_offset = cpu_to_le16(name_ofs);
	/* Setup the fields specific to non-resident attributes. */
	a->data.non_resident.lowest_vcn = 0;
	a->data.non_resident.highest_vcn = cpu_to_sle64((new_size - 1) >>
			vol->cluster_size_bits);
	a->data.non_resident.mapping_pairs_offset = cpu_to_le16(mp_ofs);
	memset(&a->data.non_resident.reserved, 0,
			sizeof(a->data.non_resident.reserved));
	a->data.non_resident.allocated_size = cpu_to_sle64(new_size);
	a->data.non_resident.data_size =
			a->data.non_resident.initialized_size =
			cpu_to_sle64(attr_size);
	if (NInoSparse(ni) || NInoCompressed(ni)) {
		a->data.non_resident.compression_unit = 0;
		if (NInoCompressed(ni) || vol->major_ver < 3)
			a->data.non_resident.compression_unit = 4;
		a->data.non_resident.compressed_size =
				a->data.non_resident.allocated_size;
	} else
		a->data.non_resident.compression_unit = 0;
	/* Generate the mapping pairs array into the attribute record. */
	err = ntfs_mapping_pairs_build(vol, (u8*)a + mp_ofs,
			arec_size - mp_ofs, rl, 0, -1, NULL);
	if (unlikely(err)) {
		ntfs_debug("Failed to build mapping pairs, error code %i.",
				err);
		goto undo_err_out;
	}
	/* Setup the in-memory attribute structure to be non-resident. */
	ni->runlist.rl = rl;
	write_lock_irqsave(&ni->size_lock, flags);
	ni->allocated_size = new_size;
	if (NInoSparse(ni) || NInoCompressed(ni)) {
		ni->itype.compressed.size = ni->allocated_size;
		if (a->data.non_resident.compression_unit) {
			ni->itype.compressed.block_size = 1U << (a->data.
					non_resident.compression_unit +
					vol->cluster_size_bits);
			ni->itype.compressed.block_size_bits =
					ffs(ni->itype.compressed.block_size) -
					1;
			ni->itype.compressed.block_clusters = 1U <<
					a->data.non_resident.compression_unit;
		} else {
			ni->itype.compressed.block_size = 0;
			ni->itype.compressed.block_size_bits = 0;
			ni->itype.compressed.block_clusters = 0;
		}
		vi->i_blocks = ni->itype.compressed.size >> 9;
	} else
		vi->i_blocks = ni->allocated_size >> 9;
	write_unlock_irqrestore(&ni->size_lock, flags);
	/*
	 * This needs to be last since the address space operations ->readpage
	 * and ->writepage can run concurrently with us as they are not
	 * serialized on i_mutex.  Note, we are not allowed to fail once we flip
	 * this switch, which is another reason to do this last.
	 */
	NInoSetNonResident(ni);
	/* Mark the mft record dirty, so it gets written back. */
	flush_dcache_mft_record_page(ctx->ntfs_ino);
	mark_mft_record_dirty(ctx->ntfs_ino);
	ntfs_attr_put_search_ctx(ctx);
	unmap_mft_record(base_ni);
	up_write(&ni->runlist.lock);
	if (page) {
		set_page_dirty(page);
		unlock_page(page);
		mark_page_accessed(page);
		page_cache_release(page);
	}
	ntfs_debug("Done.");
	return 0;
undo_err_out:
	/* Convert the attribute back into a resident attribute. */
	a->non_resident = 0;
	/* Move the attribute name if it exists and update the offset. */
	name_ofs = (offsetof(ATTR_RECORD, data.resident.reserved) +
			sizeof(a->data.resident.reserved) + 7) & ~7;
	if (a->name_length)
		memmove((u8*)a + name_ofs, (u8*)a + le16_to_cpu(a->name_offset),
				a->name_length * sizeof(ntfschar));
	mp_ofs = (name_ofs + a->name_length * sizeof(ntfschar) + 7) & ~7;
	a->name_offset = cpu_to_le16(name_ofs);
	arec_size = (mp_ofs + attr_size + 7) & ~7;
	/* Resize the resident part of the attribute record. */
	err2 = ntfs_attr_record_resize(m, a, arec_size);
	if (unlikely(err2)) {
		/*
		 * This cannot happen (well if memory corruption is at work it
		 * could happen in theory), but deal with it as well as we can.
		 * If the old size is too small, truncate the attribute,
		 * otherwise simply give it a larger allocated size.
		 * FIXME: Should check whether chkdsk complains when the
		 * allocated size is much bigger than the resident value size.
		 */
		arec_size = le32_to_cpu(a->length);
		if ((mp_ofs + attr_size) > arec_size) {
			err2 = attr_size;
			attr_size = arec_size - mp_ofs;
			ntfs_error(vol->sb, "Failed to undo partial resident "
					"to non-resident attribute "
					"conversion.  Truncating inode 0x%lx, "
					"attribute type 0x%x from %i bytes to "
					"%i bytes to maintain metadata "
					"consistency.  THIS MEANS YOU ARE "
					"LOSING %i BYTES DATA FROM THIS %s.",
					vi->i_ino,
					(unsigned)le32_to_cpu(ni->type),
					err2, attr_size, err2 - attr_size,
					((ni->type == AT_DATA) &&
					!ni->name_len) ? "FILE": "ATTRIBUTE");
			write_lock_irqsave(&ni->size_lock, flags);
			ni->initialized_size = attr_size;
			i_size_write(vi, attr_size);
			write_unlock_irqrestore(&ni->size_lock, flags);
		}
	}
	/* Setup the fields specific to resident attributes. */
	a->data.resident.value_length = cpu_to_le32(attr_size);
	a->data.resident.value_offset = cpu_to_le16(mp_ofs);
	a->data.resident.flags = old_res_attr_flags;
	memset(&a->data.resident.reserved, 0,
			sizeof(a->data.resident.reserved));
	/* Copy the data from the page back to the attribute value. */
	if (page) {
		kaddr = kmap_atomic(page, KM_USER0);
		memcpy((u8*)a + mp_ofs, kaddr, attr_size);
		kunmap_atomic(kaddr, KM_USER0);
	}
	/* Setup the allocated size in the ntfs inode in case it changed. */
	write_lock_irqsave(&ni->size_lock, flags);
	ni->allocated_size = arec_size - mp_ofs;
	write_unlock_irqrestore(&ni->size_lock, flags);
	/* Mark the mft record dirty, so it gets written back. */
	flush_dcache_mft_record_page(ctx->ntfs_ino);
	mark_mft_record_dirty(ctx->ntfs_ino);
err_out:
	if (ctx)
		ntfs_attr_put_search_ctx(ctx);
	if (m)
		unmap_mft_record(base_ni);
	ni->runlist.rl = NULL;
	up_write(&ni->runlist.lock);
rl_err_out:
	if (rl) {
		if (ntfs_cluster_free_from_rl(vol, rl) < 0) {
			ntfs_error(vol->sb, "Failed to release allocated "
					"cluster(s) in error code path.  Run "
					"chkdsk to recover the lost "
					"cluster(s).");
			NVolSetErrors(vol);
		}
		ntfs_free(rl);
page_err_out:
		unlock_page(page);
		page_cache_release(page);
	}
	if (err == -EINVAL)
		err = -EIO;
	return err;
}

/**
 * ntfs_attr_extend_allocation - extend the allocated space of an attribute
 * @ni:			ntfs inode of the attribute whose allocation to extend
 * @new_alloc_size:	new size in bytes to which to extend the allocation to
 * @new_data_size:	new size in bytes to which to extend the data to
 * @data_start:		beginning of region which is required to be non-sparse
 *
 * Extend the allocated space of an attribute described by the ntfs inode @ni
 * to @new_alloc_size bytes.  If @data_start is -1, the whole extension may be
 * implemented as a hole in the file (as long as both the volume and the ntfs
 * inode @ni have sparse support enabled).  If @data_start is >= 0, then the
 * region between the old allocated size and @data_start - 1 may be made sparse
 * but the regions between @data_start and @new_alloc_size must be backed by
 * actual clusters.
 *
 * If @new_data_size is -1, it is ignored.  If it is >= 0, then the data size
 * of the attribute is extended to @new_data_size.  Note that the i_size of the
 * vfs inode is not updated.  Only the data size in the base attribute record
 * is updated.  The caller has to update i_size separately if this is required.
 * WARNING: It is a BUG() for @new_data_size to be smaller than the old data
 * size as well as for @new_data_size to be greater than @new_alloc_size.
 *
 * For resident attributes this involves resizing the attribute record