Initial import

1 files changed, 454 insertions, 0 deletions

diff --git a/fs/ntfs/index.c b/fs/ntfs/index.c
new file mode 100644
index 000000000..096c13569
--- /dev/null
+++ b/fs/ntfs/index.c
@@ -0,0 +1,454 @@
+/*
+ * index.c - NTFS kernel index handling.  Part of the Linux-NTFS project.
+ *
+ * Copyright (c) 2004-2005 Anton Altaparmakov
+ *
+ * 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/slab.h>
+
+#include "aops.h"
+#include "collate.h"
+#include "debug.h"
+#include "index.h"
+#include "ntfs.h"
+
+/**
+ * ntfs_index_ctx_get - allocate and initialize a new index context
+ * @idx_ni:	ntfs index inode with which to initialize the context
+ *
+ * Allocate a new index context, initialize it with @idx_ni and return it.
+ * Return NULL if allocation failed.
+ *
+ * Locking:  Caller must hold i_mutex on the index inode.
+ */
+ntfs_index_context *ntfs_index_ctx_get(ntfs_inode *idx_ni)
+{
+	ntfs_index_context *ictx;
+
+	ictx = kmem_cache_alloc(ntfs_index_ctx_cache, GFP_NOFS);
+	if (ictx)
+		*ictx = (ntfs_index_context){ .idx_ni = idx_ni };
+	return ictx;
+}
+
+/**
+ * ntfs_index_ctx_put - release an index context
+ * @ictx:	index context to free
+ *
+ * Release the index context @ictx, releasing all associated resources.
+ *
+ * Locking:  Caller must hold i_mutex on the index inode.
+ */
+void ntfs_index_ctx_put(ntfs_index_context *ictx)
+{
+	if (ictx->entry) {
+		if (ictx->is_in_root) {
+			if (ictx->actx)
+				ntfs_attr_put_search_ctx(ictx->actx);
+			if (ictx->base_ni)
+				unmap_mft_record(ictx->base_ni);
+		} else {
+			struct page *page = ictx->page;
+			if (page) {
+				BUG_ON(!PageLocked(page));
+				unlock_page(page);
+				ntfs_unmap_page(page);
+			}
+		}
+	}
+	kmem_cache_free(ntfs_index_ctx_cache, ictx);
+	return;
+}
+
+/**
+ * ntfs_index_lookup - find a key in an index and return its index entry
+ * @key:	[IN] key for which to search in the index
+ * @key_len:	[IN] length of @key in bytes
+ * @ictx:	[IN/OUT] context describing the index and the returned entry
+ *
+ * Before calling ntfs_index_lookup(), @ictx must have been obtained from a
+ * call to ntfs_index_ctx_get().
+ *
+ * Look for the @key in the index specified by the index lookup context @ictx.
+ * ntfs_index_lookup() walks the contents of the index looking for the @key.
+ *
+ * If the @key is found in the index, 0 is returned and @ictx is setup to
+ * describe the index entry containing the matching @key.  @ictx->entry is the
+ * index entry and @ictx->data and @ictx->data_len are the index entry data and
+ * its length in bytes, respectively.
+ *
+ * If the @key is not found in the index, -ENOENT is returned and @ictx is
+ * setup to describe the index entry whose key collates immediately after the
+ * search @key, i.e. this is the position in the index at which an index entry
+ * with a key of @key would need to be inserted.
+ *
+ * If an error occurs return the negative error code and @ictx is left
+ * untouched.
+ *
+ * When finished with the entry and its data, call ntfs_index_ctx_put() to free
+ * the context and other associated resources.
+ *
+ * If the index entry was modified, call flush_dcache_index_entry_page()
+ * immediately after the modification and either ntfs_index_entry_mark_dirty()
+ * or ntfs_index_entry_write() before the call to ntfs_index_ctx_put() to
+ * ensure that the changes are written to disk.
+ *
+ * Locking:  - Caller must hold i_mutex on the index inode.
+ *	     - Each page cache page in the index allocation mapping must be
+ *	       locked whilst being accessed otherwise we may find a corrupt
+ *	       page due to it being under ->writepage at the moment which
+ *	       applies the mst protection fixups before writing out and then
+ *	       removes them again after the write is complete after which it 
+ *	       unlocks the page.
+ */
+int ntfs_index_lookup(const void *key, const int key_len,
+		ntfs_index_context *ictx)
+{
+	VCN vcn, old_vcn;
+	ntfs_inode *idx_ni = ictx->idx_ni;
+	ntfs_volume *vol = idx_ni->vol;
+	struct super_block *sb = vol->sb;
+	ntfs_inode *base_ni = idx_ni->ext.base_ntfs_ino;
+	MFT_RECORD *m;
+	INDEX_ROOT *ir;
+	INDEX_ENTRY *ie;
+	INDEX_ALLOCATION *ia;
+	u8 *index_end, *kaddr;
+	ntfs_attr_search_ctx *actx;
+	struct address_space *ia_mapping;
+	struct page *page;
+	int rc, err = 0;
+
+	ntfs_debug("Entering.");
+	BUG_ON(!NInoAttr(idx_ni));
+	BUG_ON(idx_ni->type != AT_INDEX_ALLOCATION);
+	BUG_ON(idx_ni->nr_extents != -1);
+	BUG_ON(!base_ni);
+	BUG_ON(!key);
+	BUG_ON(key_len <= 0);
+	if (!ntfs_is_collation_rule_supported(
+			idx_ni->itype.index.collation_rule)) {
+		ntfs_error(sb, "Index uses unsupported collation rule 0x%x.  "
+				"Aborting lookup.", le32_to_cpu(
+				idx_ni->itype.index.collation_rule));
+		return -EOPNOTSUPP;
+	}
+	/* Get hold of the mft record for the index inode. */
+	m = map_mft_record(base_ni);
+	if (IS_ERR(m)) {
+		ntfs_error(sb, "map_mft_record() failed with error code %ld.",
+				-PTR_ERR(m));
+		return PTR_ERR(m);
+	}
+	actx = ntfs_attr_get_search_ctx(base_ni, m);
+	if (unlikely(!actx)) {
+		err = -ENOMEM;
+		goto err_out;
+	}
+	/* Find the index root attribute in the mft record. */
+	err = ntfs_attr_lookup(AT_INDEX_ROOT, idx_ni->name, idx_ni->name_len,
+			CASE_SENSITIVE, 0, NULL, 0, actx);
+	if (unlikely(err)) {
+		if (err == -ENOENT) {
+			ntfs_error(sb, "Index root attribute missing in inode "
+					"0x%lx.", idx_ni->mft_no);
+			err = -EIO;
+		}
+		goto err_out;
+	}
+	/* Get to the index root value (it has been verified in read_inode). */
+	ir = (INDEX_ROOT*)((u8*)actx->attr +
+			le16_to_cpu(actx->attr->data.resident.value_offset));
+	index_end = (u8*)&ir->index + le32_to_cpu(ir->index.index_length);
+	/* The first index entry. */
+	ie = (INDEX_ENTRY*)((u8*)&ir->index +
+			le32_to_cpu(ir->index.entries_offset));
+	/*
+	 * 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*)actx->mrec || (u8*)ie +
+				sizeof(INDEX_ENTRY_HEADER) > index_end ||
+				(u8*)ie + le16_to_cpu(ie->length) > index_end)
+			goto idx_err_out;
+		/*
+		 * The last entry cannot contain a key.  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))
+			goto idx_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)) {
+ir_done:
+			ictx->is_in_root = true;
+			ictx->ir = ir;
+			ictx->actx = actx;
+			ictx->base_ni = base_ni;
+			ictx->ia = NULL;
+			ictx->page = NULL;
+done:
+			ictx->entry = ie;
+			ictx->data = (u8*)ie +
+					le16_to_cpu(ie->data.vi.data_offset);
+			ictx->data_len = le16_to_cpu(ie->data.vi.data_length);
+			ntfs_debug("Done.");
+			return err;
+		}
+		/*
+		 * 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 ir_done;
+		/* The keys are not equal, continue the search. */
+	}
+	/*
+	 * We have finished with this index without success.  Check for the
+	 * presence of a child node and if not present setup @ictx and return
+	 * -ENOENT.
+	 */
+	if (!(ie->flags & INDEX_ENTRY_NODE)) {
+		ntfs_debug("Entry not found.");
+		err = -ENOENT;
+		goto ir_done;
+	} /* Child node present, descend into it. */
+	/* Consistency check: Verify that an index allocation exists. */
+	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);
+		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);
+		goto unm_err_out;
+	}
+	/* Catch multi sector transfer fixup errors. */
+	if (unlikely(!ntfs_is_indx_record(ia->magic))) {
+		ntfs_error(sb, "Index record with vcn 0x%llx is corrupt.  "
+				"Corrupt inode 0x%lx.  Run chkdsk.",
+				(long long)vcn, idx_ni->mft_no);
+		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);
+		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);
+		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);
+		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);
+		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);
+			goto unm_err_out;
+		}
+		/*
+		 * The last entry cannot contain a key.  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);
+			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);
+		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);
+unm_err_out:
+	unlock_page(page);
+	ntfs_unmap_page(page);
+err_out:
+	if (!err)
+		err = -EIO;
+	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.");
+	goto err_out;
+}