index.c

来自「Linux Kernel 2.6.9 for OMAP1710」· C语言 代码 · 共 517 行 · 第 1/2 页

	if (!NInoIndexAllocPresent(idx_ni)) {
		ntfs_error(sb, "No index allocation attribute but index entry "
				"requires one.  Inode 0x%lx is corrupt or "
				"driver bug.", idx_ni->mft_no);
		err = -EIO;
		goto err_out;
	}
	/* Get the starting vcn of the index_block holding the child node. */
	vcn = sle64_to_cpup((sle64*)((u8*)ie + le16_to_cpu(ie->length) - 8));
	ia_mapping = VFS_I(idx_ni)->i_mapping;
	/*
	 * We are done with the index root and the mft record.  Release them,
	 * otherwise we deadlock with ntfs_map_page().
	 */
	ntfs_attr_put_search_ctx(actx);
	unmap_mft_record(base_ni);
	m = NULL;
	actx = NULL;
descend_into_child_node:
	/*
	 * Convert vcn to index into the index allocation attribute in units
	 * of PAGE_CACHE_SIZE and map the page cache page, reading it from
	 * disk if necessary.
	 */
	page = ntfs_map_page(ia_mapping, vcn <<
			idx_ni->itype.index.vcn_size_bits >> PAGE_CACHE_SHIFT);
	if (IS_ERR(page)) {
		ntfs_error(sb, "Failed to map index page, error %ld.",
				-PTR_ERR(page));
		err = PTR_ERR(page);
		goto err_out;
	}
	lock_page(page);
	kaddr = (u8*)page_address(page);
fast_descend_into_child_node:
	/* Get to the index allocation block. */
	ia = (INDEX_ALLOCATION*)(kaddr + ((vcn <<
			idx_ni->itype.index.vcn_size_bits) & ~PAGE_CACHE_MASK));
	/* Bounds checks. */
	if ((u8*)ia < kaddr || (u8*)ia > kaddr + PAGE_CACHE_SIZE) {
		ntfs_error(sb, "Out of bounds check failed.  Corrupt inode "
				"0x%lx or driver bug.", idx_ni->mft_no);
		err = -EIO;
		goto unm_err_out;
	}
	if (sle64_to_cpu(ia->index_block_vcn) != vcn) {
		ntfs_error(sb, "Actual VCN (0x%llx) of index buffer is "
				"different from expected VCN (0x%llx).  Inode "
				"0x%lx is corrupt or driver bug.",
				(unsigned long long)
				sle64_to_cpu(ia->index_block_vcn),
				(unsigned long long)vcn, idx_ni->mft_no);
		err = -EIO;
		goto unm_err_out;
	}
	if (le32_to_cpu(ia->index.allocated_size) + 0x18 !=
			idx_ni->itype.index.block_size) {
		ntfs_error(sb, "Index buffer (VCN 0x%llx) of inode 0x%lx has "
				"a size (%u) differing from the index "
				"specified size (%u).  Inode is corrupt or "
				"driver bug.", (unsigned long long)vcn,
				idx_ni->mft_no,
				le32_to_cpu(ia->index.allocated_size) + 0x18,
				idx_ni->itype.index.block_size);
		err = -EIO;
		goto unm_err_out;
	}
	index_end = (u8*)ia + idx_ni->itype.index.block_size;
	if (index_end > kaddr + PAGE_CACHE_SIZE) {
		ntfs_error(sb, "Index buffer (VCN 0x%llx) of inode 0x%lx "
				"crosses page boundary.  Impossible!  Cannot "
				"access!  This is probably a bug in the "
				"driver.", (unsigned long long)vcn,
				idx_ni->mft_no);
		err = -EIO;
		goto unm_err_out;
	}
	index_end = (u8*)&ia->index + le32_to_cpu(ia->index.index_length);
	if (index_end > (u8*)ia + idx_ni->itype.index.block_size) {
		ntfs_error(sb, "Size of index buffer (VCN 0x%llx) of inode "
				"0x%lx exceeds maximum size.",
				(unsigned long long)vcn, idx_ni->mft_no);
		err = -EIO;
		goto unm_err_out;
	}
	/* The first index entry. */
	ie = (INDEX_ENTRY*)((u8*)&ia->index +
			le32_to_cpu(ia->index.entries_offset));
	/*
	 * Iterate similar to above big loop but applied to index buffer, thus
	 * loop until we exceed valid memory (corruption case) or until we
	 * reach the last entry.
	 */
	for (;; ie = (INDEX_ENTRY*)((u8*)ie + le16_to_cpu(ie->length))) {
		/* Bounds checks. */
		if ((u8*)ie < (u8*)ia || (u8*)ie +
				sizeof(INDEX_ENTRY_HEADER) > index_end ||
				(u8*)ie + le16_to_cpu(ie->length) > index_end) {
			ntfs_error(sb, "Index entry out of bounds in inode "
					"0x%lx.", idx_ni->mft_no);
			err = -EIO;
			goto unm_err_out;
		}
		/*
		 * The last entry cannot contain a ket.  It can however contain
		 * a pointer to a child node in the B+tree so we just break out.
		 */
		if (ie->flags & INDEX_ENTRY_END)
			break;
		/* Further bounds checks. */
		if ((u32)sizeof(INDEX_ENTRY_HEADER) +
				le16_to_cpu(ie->key_length) >
				le16_to_cpu(ie->data.vi.data_offset) ||
				(u32)le16_to_cpu(ie->data.vi.data_offset) +
				le16_to_cpu(ie->data.vi.data_length) >
				le16_to_cpu(ie->length)) {
			ntfs_error(sb, "Index entry out of bounds in inode "
					"0x%lx.", idx_ni->mft_no);
			err = -EIO;
			goto unm_err_out;
		}
		/* If the keys match perfectly, we setup @ictx and return 0. */
		if ((key_len == le16_to_cpu(ie->key_length)) && !memcmp(key,
				&ie->key, key_len)) {
ia_done:
			ictx->is_in_root = FALSE;
			ictx->actx = NULL;
			ictx->base_ni = NULL;
			ictx->ia = ia;
			ictx->page = page;
			goto done;
		}
		/*
		 * Not a perfect match, need to do full blown collation so we
		 * know which way in the B+tree we have to go.
		 */
		rc = ntfs_collate(vol, idx_ni->itype.index.collation_rule, key,
				key_len, &ie->key, le16_to_cpu(ie->key_length));
		/*
		 * If @key collates before the key of the current entry, there
		 * is definitely no such key in this index but we might need to
		 * descend into the B+tree so we just break out of the loop.
		 */
		if (rc == -1)
			break;
		/*
		 * A match should never happen as the memcmp() call should have
		 * cought it, but we still treat it correctly.
		 */
		if (!rc)
			goto ia_done;
		/* The keys are not equal, continue the search. */
	}
	/*
	 * We have finished with this index buffer without success.  Check for
	 * the presence of a child node and if not present return -ENOENT.
	 */
	if (!(ie->flags & INDEX_ENTRY_NODE)) {
		ntfs_debug("Entry not found.");
		err = -ENOENT;
		goto ia_done;
	}
	if ((ia->index.flags & NODE_MASK) == LEAF_NODE) {
		ntfs_error(sb, "Index entry with child node found in a leaf "
				"node in inode 0x%lx.", idx_ni->mft_no);
		err = -EIO;
		goto unm_err_out;
	}
	/* Child node present, descend into it. */
	old_vcn = vcn;
	vcn = sle64_to_cpup((sle64*)((u8*)ie + le16_to_cpu(ie->length) - 8));
	if (vcn >= 0) {
		/*
		 * If vcn is in the same page cache page as old_vcn we recycle
		 * the mapped page.
		 */
		if (old_vcn << vol->cluster_size_bits >>
				PAGE_CACHE_SHIFT == vcn <<
				vol->cluster_size_bits >>
				PAGE_CACHE_SHIFT)
			goto fast_descend_into_child_node;
		unlock_page(page);
		ntfs_unmap_page(page);
		goto descend_into_child_node;
	}
	ntfs_error(sb, "Negative child node vcn in inode 0x%lx.",
			idx_ni->mft_no);
	err = -EIO;
unm_err_out:
	unlock_page(page);
	ntfs_unmap_page(page);
err_out:
	if (actx)
		ntfs_attr_put_search_ctx(actx);
	if (m)
		unmap_mft_record(base_ni);
	return err;
idx_err_out:
	ntfs_error(sb, "Corrupt index.  Aborting lookup.");
	err = -EIO;
	goto err_out;
}

#ifdef NTFS_RW

/**
 * __ntfs_index_entry_mark_dirty - mark an index allocation entry dirty
 * @ictx:	ntfs index context describing the index entry
 *
 * NOTE: You want to use fs/ntfs/index.h::ntfs_index_entry_mark_dirty() instead!
 * 
 * Mark the index allocation entry described by the index entry context @ictx
 * dirty.
 *
 * The index entry must be in an index block belonging to the index allocation
 * attribute.  Mark the buffers belonging to the index record as well as the
 * page cache page the index block is in dirty.  This automatically marks the
 * VFS inode of the ntfs index inode to which the index entry belongs dirty,
 * too (I_DIRTY_PAGES) and this in turn ensures the page buffers, and hence the
 * dirty index block, will be written out to disk later.
 */
void __ntfs_index_entry_mark_dirty(ntfs_index_context *ictx)
{
	ntfs_inode *ni;
	struct page *page;
	struct buffer_head *bh, *head;
	unsigned int rec_start, rec_end, bh_size, bh_start, bh_end;

	BUG_ON(ictx->is_in_root);
	ni = ictx->idx_ni;
	page = ictx->page;
	BUG_ON(!page_has_buffers(page));
	/*
	 * If the index block is the same size as the page cache page, set all
	 * the buffers in the page, as well as the page itself, dirty.
	 */
	if (ni->itype.index.block_size == PAGE_CACHE_SIZE) {
		__set_page_dirty_buffers(page);
		return;
	}
	/* Set only the buffers in which the index block is located dirty. */
	rec_start = (unsigned int)((u8*)ictx->ia - (u8*)page_address(page));
	rec_end = rec_start + ni->itype.index.block_size;
	bh_size = ni->vol->sb->s_blocksize;
	bh_start = 0;
	bh = head = page_buffers(page);
	do {
		bh_end = bh_start + bh_size;
		if ((bh_start >= rec_start) && (bh_end <= rec_end))
			set_buffer_dirty(bh);
		bh_start = bh_end;
	} while ((bh = bh->b_this_page) != head);
	/* Finally, set the page itself dirty, too. */
	__set_page_dirty_nobuffers(page);
}

#endif /* NTFS_RW */