mft.c

linux 内核源代码

	pass_end = NTFS_I(vol->mft_ino)->allocated_size >>
			vol->mft_record_size_bits;
	read_unlock_irqrestore(&NTFS_I(vol->mft_ino)->size_lock, flags);
	read_lock_irqsave(&NTFS_I(vol->mftbmp_ino)->size_lock, flags);
	ll = NTFS_I(vol->mftbmp_ino)->initialized_size << 3;
	read_unlock_irqrestore(&NTFS_I(vol->mftbmp_ino)->size_lock, flags);
	if (pass_end > ll)
		pass_end = ll;
	pass = 1;
	if (!base_ni)
		data_pos = vol->mft_data_pos;
	else
		data_pos = base_ni->mft_no + 1;
	if (data_pos < 24)
		data_pos = 24;
	if (data_pos >= pass_end) {
		data_pos = 24;
		pass = 2;
		/* This happens on a freshly formatted volume. */
		if (data_pos >= pass_end)
			return -ENOSPC;
	}
	pass_start = data_pos;
	ntfs_debug("Starting bitmap search: pass %u, pass_start 0x%llx, "
			"pass_end 0x%llx, data_pos 0x%llx.", pass,
			(long long)pass_start, (long long)pass_end,
			(long long)data_pos);
	/* Loop until a free mft record is found. */
	for (; pass <= 2;) {
		/* Cap size to pass_end. */
		ofs = data_pos >> 3;
		page_ofs = ofs & ~PAGE_CACHE_MASK;
		size = PAGE_CACHE_SIZE - page_ofs;
		ll = ((pass_end + 7) >> 3) - ofs;
		if (size > ll)
			size = ll;
		size <<= 3;
		/*
		 * If we are still within the active pass, search the next page
		 * for a zero bit.
		 */
		if (size) {
			page = ntfs_map_page(mftbmp_mapping,
					ofs >> PAGE_CACHE_SHIFT);
			if (unlikely(IS_ERR(page))) {
				ntfs_error(vol->sb, "Failed to read mft "
						"bitmap, aborting.");
				return PTR_ERR(page);
			}
			buf = (u8*)page_address(page) + page_ofs;
			bit = data_pos & 7;
			data_pos &= ~7ull;
			ntfs_debug("Before inner for loop: size 0x%x, "
					"data_pos 0x%llx, bit 0x%llx", size,
					(long long)data_pos, (long long)bit);
			for (; bit < size && data_pos + bit < pass_end;
					bit &= ~7ull, bit += 8) {
				byte = buf + (bit >> 3);
				if (*byte == 0xff)
					continue;
				b = ffz((unsigned long)*byte);
				if (b < 8 && b >= (bit & 7)) {
					ll = data_pos + (bit & ~7ull) + b;
					if (unlikely(ll > (1ll << 32))) {
						ntfs_unmap_page(page);
						return -ENOSPC;
					}
					*byte |= 1 << b;
					flush_dcache_page(page);
					set_page_dirty(page);
					ntfs_unmap_page(page);
					ntfs_debug("Done.  (Found and "
							"allocated mft record "
							"0x%llx.)",
							(long long)ll);
					return ll;
				}
			}
			ntfs_debug("After inner for loop: size 0x%x, "
					"data_pos 0x%llx, bit 0x%llx", size,
					(long long)data_pos, (long long)bit);
			data_pos += size;
			ntfs_unmap_page(page);
			/*
			 * If the end of the pass has not been reached yet,
			 * continue searching the mft bitmap for a zero bit.
			 */
			if (data_pos < pass_end)
				continue;
		}
		/* Do the next pass. */
		if (++pass == 2) {
			/*
			 * Starting the second pass, in which we scan the first
			 * part of the zone which we omitted earlier.
			 */
			pass_end = pass_start;
			data_pos = pass_start = 24;
			ntfs_debug("pass %i, pass_start 0x%llx, pass_end "
					"0x%llx.", pass, (long long)pass_start,
					(long long)pass_end);
			if (data_pos >= pass_end)
				break;
		}
	}
	/* No free mft records in currently initialized mft bitmap. */
	ntfs_debug("Done.  (No free mft records left in currently initialized "
			"mft bitmap.)");
	return -ENOSPC;
}

/**
 * ntfs_mft_bitmap_extend_allocation_nolock - extend mft bitmap by a cluster
 * @vol:	volume on which to extend the mft bitmap attribute
 *
 * Extend the mft bitmap attribute on the ntfs volume @vol by one cluster.
 *
 * Note: Only changes allocated_size, i.e. does not touch initialized_size or
 * data_size.
 *
 * Return 0 on success and -errno on error.
 *
 * Locking: - Caller must hold vol->mftbmp_lock for writing.
 *	    - This function takes NTFS_I(vol->mftbmp_ino)->runlist.lock for
 *	      writing and releases it before returning.
 *	    - This function takes vol->lcnbmp_lock for writing and releases it
 *	      before returning.
 */
static int ntfs_mft_bitmap_extend_allocation_nolock(ntfs_volume *vol)
{
	LCN lcn;
	s64 ll;
	unsigned long flags;
	struct page *page;
	ntfs_inode *mft_ni, *mftbmp_ni;
	runlist_element *rl, *rl2 = NULL;
	ntfs_attr_search_ctx *ctx = NULL;
	MFT_RECORD *mrec;
	ATTR_RECORD *a = NULL;
	int ret, mp_size;
	u32 old_alen = 0;
	u8 *b, tb;
	struct {
		u8 added_cluster:1;
		u8 added_run:1;
		u8 mp_rebuilt:1;
	} status = { 0, 0, 0 };

	ntfs_debug("Extending mft bitmap allocation.");
	mft_ni = NTFS_I(vol->mft_ino);
	mftbmp_ni = NTFS_I(vol->mftbmp_ino);
	/*
	 * Determine the last lcn of the mft bitmap.  The allocated size of the
	 * mft bitmap cannot be zero so we are ok to do this.
	 */
	down_write(&mftbmp_ni->runlist.lock);
	read_lock_irqsave(&mftbmp_ni->size_lock, flags);
	ll = mftbmp_ni->allocated_size;
	read_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
	rl = ntfs_attr_find_vcn_nolock(mftbmp_ni,
			(ll - 1) >> vol->cluster_size_bits, NULL);
	if (unlikely(IS_ERR(rl) || !rl->length || rl->lcn < 0)) {
		up_write(&mftbmp_ni->runlist.lock);
		ntfs_error(vol->sb, "Failed to determine last allocated "
				"cluster of mft bitmap attribute.");
		if (!IS_ERR(rl))
			ret = -EIO;
		else
			ret = PTR_ERR(rl);
		return ret;
	}
	lcn = rl->lcn + rl->length;
	ntfs_debug("Last lcn of mft bitmap attribute is 0x%llx.",
			(long long)lcn);
	/*
	 * Attempt to get the cluster following the last allocated cluster by
	 * hand as it may be in the MFT zone so the allocator would not give it
	 * to us.
	 */
	ll = lcn >> 3;
	page = ntfs_map_page(vol->lcnbmp_ino->i_mapping,
			ll >> PAGE_CACHE_SHIFT);
	if (IS_ERR(page)) {
		up_write(&mftbmp_ni->runlist.lock);
		ntfs_error(vol->sb, "Failed to read from lcn bitmap.");
		return PTR_ERR(page);
	}
	b = (u8*)page_address(page) + (ll & ~PAGE_CACHE_MASK);
	tb = 1 << (lcn & 7ull);
	down_write(&vol->lcnbmp_lock);
	if (*b != 0xff && !(*b & tb)) {
		/* Next cluster is free, allocate it. */
		*b |= tb;
		flush_dcache_page(page);
		set_page_dirty(page);
		up_write(&vol->lcnbmp_lock);
		ntfs_unmap_page(page);
		/* Update the mft bitmap runlist. */
		rl->length++;
		rl[1].vcn++;
		status.added_cluster = 1;
		ntfs_debug("Appending one cluster to mft bitmap.");
	} else {
		up_write(&vol->lcnbmp_lock);
		ntfs_unmap_page(page);
		/* Allocate a cluster from the DATA_ZONE. */
		rl2 = ntfs_cluster_alloc(vol, rl[1].vcn, 1, lcn, DATA_ZONE,
				true);
		if (IS_ERR(rl2)) {
			up_write(&mftbmp_ni->runlist.lock);
			ntfs_error(vol->sb, "Failed to allocate a cluster for "
					"the mft bitmap.");
			return PTR_ERR(rl2);
		}
		rl = ntfs_runlists_merge(mftbmp_ni->runlist.rl, rl2);
		if (IS_ERR(rl)) {
			up_write(&mftbmp_ni->runlist.lock);
			ntfs_error(vol->sb, "Failed to merge runlists for mft "
					"bitmap.");
			if (ntfs_cluster_free_from_rl(vol, rl2)) {
				ntfs_error(vol->sb, "Failed to dealocate "
						"allocated cluster.%s", es);
				NVolSetErrors(vol);
			}
			ntfs_free(rl2);
			return PTR_ERR(rl);
		}
		mftbmp_ni->runlist.rl = rl;
		status.added_run = 1;
		ntfs_debug("Adding one run to mft bitmap.");
		/* Find the last run in the new runlist. */
		for (; rl[1].length; rl++)
			;
	}
	/*
	 * Update the attribute record as well.  Note: @rl is the last
	 * (non-terminator) runlist element of mft bitmap.
	 */
	mrec = map_mft_record(mft_ni);
	if (IS_ERR(mrec)) {
		ntfs_error(vol->sb, "Failed to map mft record.");
		ret = PTR_ERR(mrec);
		goto undo_alloc;
	}
	ctx = ntfs_attr_get_search_ctx(mft_ni, mrec);
	if (unlikely(!ctx)) {
		ntfs_error(vol->sb, "Failed to get search context.");
		ret = -ENOMEM;
		goto undo_alloc;
	}
	ret = ntfs_attr_lookup(mftbmp_ni->type, mftbmp_ni->name,
			mftbmp_ni->name_len, CASE_SENSITIVE, rl[1].vcn, NULL,
			0, ctx);
	if (unlikely(ret)) {
		ntfs_error(vol->sb, "Failed to find last attribute extent of "
				"mft bitmap attribute.");
		if (ret == -ENOENT)
			ret = -EIO;
		goto undo_alloc;
	}
	a = ctx->attr;
	ll = sle64_to_cpu(a->data.non_resident.lowest_vcn);
	/* Search back for the previous last allocated cluster of mft bitmap. */
	for (rl2 = rl; rl2 > mftbmp_ni->runlist.rl; rl2--) {
		if (ll >= rl2->vcn)
			break;
	}
	BUG_ON(ll < rl2->vcn);
	BUG_ON(ll >= rl2->vcn + rl2->length);
	/* Get the size for the new mapping pairs array for this extent. */
	mp_size = ntfs_get_size_for_mapping_pairs(vol, rl2, ll, -1);
	if (unlikely(mp_size <= 0)) {
		ntfs_error(vol->sb, "Get size for mapping pairs failed for "
				"mft bitmap attribute extent.");
		ret = mp_size;
		if (!ret)
			ret = -EIO;
		goto undo_alloc;
	}
	/* Expand the attribute record if necessary. */
	old_alen = le32_to_cpu(a->length);
	ret = ntfs_attr_record_resize(ctx->mrec, a, mp_size +
			le16_to_cpu(a->data.non_resident.mapping_pairs_offset));
	if (unlikely(ret)) {
		if (ret != -ENOSPC) {
			ntfs_error(vol->sb, "Failed to resize attribute "
					"record for mft bitmap attribute.");
			goto undo_alloc;
		}
		// TODO: Deal with this by moving this extent to a new mft
		// record or by starting a new extent in a new mft record or by
		// moving other attributes out of this mft record.
		// Note: It will need to be a special mft record and if none of
		// those are available it gets rather complicated...
		ntfs_error(vol->sb, "Not enough space in this mft record to "
				"accomodate extended mft bitmap attribute "
				"extent.  Cannot handle this yet.");
		ret = -EOPNOTSUPP;
		goto undo_alloc;
	}
	status.mp_rebuilt = 1;
	/* Generate the mapping pairs array directly into the attr record. */
	ret = ntfs_mapping_pairs_build(vol, (u8*)a +
			le16_to_cpu(a->data.non_resident.mapping_pairs_offset),
			mp_size, rl2, ll, -1, NULL);
	if (unlikely(ret)) {
		ntfs_error(vol->sb, "Failed to build mapping pairs array for "
				"mft bitmap attribute.");
		goto undo_alloc;
	}
	/* Update the highest_vcn. */
	a->data.non_resident.highest_vcn = cpu_to_sle64(rl[1].vcn - 1);
	/*
	 * We now have extended the mft bitmap allocated_size by one cluster.
	 * Reflect this in the ntfs_inode structure and the attribute record.
	 */
	if (a->data.non_resident.lowest_vcn) {
		/*
		 * We are not in the first attribute extent, switch to it, but
		 * first ensure the changes will make it to disk later.
		 */
		flush_dcache_mft_record_page(ctx->ntfs_ino);
		mark_mft_record_dirty(ctx->ntfs_ino);
		ntfs_attr_reinit_search_ctx(ctx);
		ret = ntfs_attr_lookup(mftbmp_ni->type, mftbmp_ni->name,
				mftbmp_ni->name_len, CASE_SENSITIVE, 0, NULL,
				0, ctx);
		if (unlikely(ret)) {
			ntfs_error(vol->sb, "Failed to find first attribute "
					"extent of mft bitmap attribute.");
			goto restore_undo_alloc;
		}
		a = ctx->attr;
	}
	write_lock_irqsave(&mftbmp_ni->size_lock, flags);
	mftbmp_ni->allocated_size += vol->cluster_size;
	a->data.non_resident.allocated_size =
			cpu_to_sle64(mftbmp_ni->allocated_size);
	write_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
	/* Ensure the changes make it to disk. */
	flush_dcache_mft_record_page(ctx->ntfs_ino);
	mark_mft_record_dirty(ctx->ntfs_ino);
	ntfs_attr_put_search_ctx(ctx);
	unmap_mft_record(mft_ni);
	up_write(&mftbmp_ni->runlist.lock);
	ntfs_debug("Done.");
	return 0;
restore_undo_alloc:
	ntfs_attr_reinit_search_ctx(ctx);
	if (ntfs_attr_lookup(mftbmp_ni->type, mftbmp_ni->name,
			mftbmp_ni->name_len, CASE_SENSITIVE, rl[1].vcn, NULL,
			0, ctx)) {
		ntfs_error(vol->sb, "Failed to find last attribute extent of "
				"mft bitmap attribute.%s", es);
		write_lock_irqsave(&mftbmp_ni->size_lock, flags);
		mftbmp_ni->allocated_size += vol->cluster_size;
		write_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
		ntfs_attr_put_search_ctx(ctx);
		unmap_mft_record(mft_ni);
		up_write(&mftbmp_ni->runlist.lock);
		/*
		 * The only thing that is now wrong is ->allocated_size of the
		 * base attribute extent which chkdsk should be able to fix.
		 */
		NVolSetErrors(vol);
		return ret;
	}
	a = ctx->attr;
	a->data.non_resident.highest_vcn = cpu_to_sle64(rl[1].vcn - 2);
undo_alloc:
	if (status.added_cluster) {
		/* Truncate the last run in the runlist by one cluster. */
		rl->length--;
		rl[1].vcn--;
	} else if (status.added_run) {
		lcn = rl->lcn;
		/* Remove the last run from the runlist. */
		rl->lcn = rl[1].lcn;
		rl->length = 0;
	}
	/* Deallocate the cluster. */
	down_write(&vol->lcnbmp_lock);
	if (ntfs_bitmap_clear_bit(vol->lcnbmp_ino, lcn)) {