From 589dc2602f2a1b7fa5e59b90f548af189f128d77 Mon Sep 17 00:00:00 2001
From: Tao Ma <tao.ma@oracle.com>
Date: Mon, 18 Aug 2008 17:38:51 +0800
Subject: ocfs2: Add xattr lookup code xattr btrees

Add code to lookup a given extended attribute in the xattr btree. Lookup
follows this general scheme:

1. Use ocfs2_xattr_get_rec to find the xattr extent record

2. Find the xattr bucket within the extent which may contain this xattr

3. Iterate the bucket to find the xattr. In ocfs2_xattr_block_get(), we need
   to recalcuate the block offset and name offset for the right position of
   name/value.

Signed-off-by: Tao Ma <tao.ma@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c
index fb17f7f..acccdfa 100644
--- a/fs/ocfs2/xattr.c
+++ b/fs/ocfs2/xattr.c
@@ -99,12 +99,25 @@ struct ocfs2_xattr_search {
 	 */
 	struct buffer_head *xattr_bh;
 	struct ocfs2_xattr_header *header;
+	struct ocfs2_xattr_bucket bucket;
 	void *base;
 	void *end;
 	struct ocfs2_xattr_entry *here;
 	int not_found;
 };
 
+static int ocfs2_xattr_bucket_get_name_value(struct inode *inode,
+					     struct ocfs2_xattr_header *xh,
+					     int index,
+					     int *block_off,
+					     int *new_offset);
+
+static int ocfs2_xattr_index_block_find(struct inode *inode,
+					struct buffer_head *root_bh,
+					int name_index,
+					const char *name,
+					struct ocfs2_xattr_search *xs);
+
 static int ocfs2_xattr_tree_list_index_block(struct inode *inode,
 					struct ocfs2_xattr_tree_root *xt,
 					char *buffer,
@@ -604,7 +617,7 @@ static int ocfs2_xattr_find_entry(int name_index,
 }
 
 static int ocfs2_xattr_get_value_outside(struct inode *inode,
-					 struct ocfs2_xattr_search *xs,
+					 struct ocfs2_xattr_value_root *xv,
 					 void *buffer,
 					 size_t len)
 {
@@ -613,12 +626,8 @@ static int ocfs2_xattr_get_value_outside(struct inode *inode,
 	int i, ret = 0;
 	size_t cplen, blocksize;
 	struct buffer_head *bh = NULL;
-	struct ocfs2_xattr_value_root *xv;
 	struct ocfs2_extent_list *el;
 
-	xv = (struct ocfs2_xattr_value_root *)
-		(xs->base + le16_to_cpu(xs->here->xe_name_offset) +
-		OCFS2_XATTR_SIZE(xs->here->xe_name_len));
 	el = &xv->xr_list;
 	clusters = le32_to_cpu(xv->xr_clusters);
 	bpc = ocfs2_clusters_to_blocks(inode->i_sb, 1);
@@ -668,6 +677,7 @@ static int ocfs2_xattr_ibody_get(struct inode *inode,
 {
 	struct ocfs2_inode_info *oi = OCFS2_I(inode);
 	struct ocfs2_dinode *di = (struct ocfs2_dinode *)xs->inode_bh->b_data;
+	struct ocfs2_xattr_value_root *xv;
 	size_t size;
 	int ret = 0;
 
@@ -692,7 +702,11 @@ static int ocfs2_xattr_ibody_get(struct inode *inode,
 			       le16_to_cpu(xs->here->xe_name_offset) +
 			       OCFS2_XATTR_SIZE(xs->here->xe_name_len), size);
 		} else {
-			ret = ocfs2_xattr_get_value_outside(inode, xs,
+			xv = (struct ocfs2_xattr_value_root *)
+				(xs->base + le16_to_cpu(
+				 xs->here->xe_name_offset) +
+				OCFS2_XATTR_SIZE(xs->here->xe_name_len));
+			ret = ocfs2_xattr_get_value_outside(inode, xv,
 							    buffer, size);
 			if (ret < 0) {
 				mlog_errno(ret);
@@ -714,12 +728,15 @@ static int ocfs2_xattr_block_get(struct inode *inode,
 	struct ocfs2_dinode *di = (struct ocfs2_dinode *)xs->inode_bh->b_data;
 	struct buffer_head *blk_bh = NULL;
 	struct ocfs2_xattr_block *xb;
+	struct ocfs2_xattr_value_root *xv;
 	size_t size;
-	int ret = -ENODATA;
+	int ret = -ENODATA, name_offset, name_len, block_off, i;
 
 	if (!di->i_xattr_loc)
 		return ret;
 
+	memset(&xs->bucket, 0, sizeof(xs->bucket));
+
 	ret = ocfs2_read_block(OCFS2_SB(inode->i_sb),
 			       le64_to_cpu(di->i_xattr_loc),
 			       &blk_bh, OCFS2_BH_CACHED, inode);
@@ -736,12 +753,19 @@ static int ocfs2_xattr_block_get(struct inode *inode,
 
 	xs->xattr_bh = blk_bh;
 	xb = (struct ocfs2_xattr_block *)blk_bh->b_data;
-	xs->header = &xb->xb_attrs.xb_header;
-	xs->base = (void *)xs->header;
-	xs->end = (void *)(blk_bh->b_data) + blk_bh->b_size;
-	xs->here = xs->header->xh_entries;
 
-	ret = ocfs2_xattr_find_entry(name_index, name, xs);
+	if (!(le16_to_cpu(xb->xb_flags) & OCFS2_XATTR_INDEXED)) {
+		xs->header = &xb->xb_attrs.xb_header;
+		xs->base = (void *)xs->header;
+		xs->end = (void *)(blk_bh->b_data) + blk_bh->b_size;
+		xs->here = xs->header->xh_entries;
+
+		ret = ocfs2_xattr_find_entry(name_index, name, xs);
+	} else
+		ret = ocfs2_xattr_index_block_find(inode, blk_bh,
+						   name_index,
+						   name, xs);
+
 	if (ret)
 		goto cleanup;
 	size = le64_to_cpu(xs->here->xe_value_size);
@@ -749,12 +773,26 @@ static int ocfs2_xattr_block_get(struct inode *inode,
 		ret = -ERANGE;
 		if (size > buffer_size)
 			goto cleanup;
+
+		name_offset = le16_to_cpu(xs->here->xe_name_offset);
+		name_len = OCFS2_XATTR_SIZE(xs->here->xe_name_len);
+		i = xs->here - xs->header->xh_entries;
+
+		if (le16_to_cpu(xb->xb_flags) & OCFS2_XATTR_INDEXED) {
+			ret = ocfs2_xattr_bucket_get_name_value(inode,
+								xs->bucket.xh,
+								i,
+								&block_off,
+								&name_offset);
+			xs->base = xs->bucket.bhs[block_off]->b_data;
+		}
 		if (ocfs2_xattr_is_local(xs->here)) {
 			memcpy(buffer, (void *)xs->base +
-			       le16_to_cpu(xs->here->xe_name_offset) +
-			       OCFS2_XATTR_SIZE(xs->here->xe_name_len), size);
+			       name_offset + name_len, size);
 		} else {
-			ret = ocfs2_xattr_get_value_outside(inode, xs,
+			xv = (struct ocfs2_xattr_value_root *)
+				(xs->base + name_offset + name_len);
+			ret = ocfs2_xattr_get_value_outside(inode, xv,
 							    buffer, size);
 			if (ret < 0) {
 				mlog_errno(ret);
@@ -764,8 +802,11 @@ static int ocfs2_xattr_block_get(struct inode *inode,
 	}
 	ret = size;
 cleanup:
-	brelse(blk_bh);
+	for (i = 0; i < OCFS2_XATTR_MAX_BLOCKS_PER_BUCKET; i++)
+		brelse(xs->bucket.bhs[i]);
+	memset(&xs->bucket, 0, sizeof(xs->bucket));
 
+	brelse(blk_bh);
 	return ret;
 }
 
@@ -1679,6 +1720,7 @@ static int ocfs2_xattr_block_find(struct inode *inode,
 {
 	struct ocfs2_dinode *di = (struct ocfs2_dinode *)xs->inode_bh->b_data;
 	struct buffer_head *blk_bh = NULL;
+	struct ocfs2_xattr_block *xb;
 	int ret = 0;
 
 	if (!di->i_xattr_loc)
@@ -1699,20 +1741,26 @@ static int ocfs2_xattr_block_find(struct inode *inode,
 	}
 
 	xs->xattr_bh = blk_bh;
-	xs->header = &((struct ocfs2_xattr_block *)blk_bh->b_data)->
-			xb_attrs.xb_header;
-	xs->base = (void *)xs->header;
-	xs->end = (void *)(blk_bh->b_data) + blk_bh->b_size;
-	xs->here = xs->header->xh_entries;
+	xb = (struct ocfs2_xattr_block *)blk_bh->b_data;
+
+	if (!(le16_to_cpu(xb->xb_flags) & OCFS2_XATTR_INDEXED)) {
+		xs->header = &xb->xb_attrs.xb_header;
+		xs->base = (void *)xs->header;
+		xs->end = (void *)(blk_bh->b_data) + blk_bh->b_size;
+		xs->here = xs->header->xh_entries;
+
+		ret = ocfs2_xattr_find_entry(name_index, name, xs);
+	} else
+		ret = ocfs2_xattr_index_block_find(inode, blk_bh,
+						   name_index,
+						   name, xs);
 
-	ret = ocfs2_xattr_find_entry(name_index, name, xs);
 	if (ret && ret != -ENODATA) {
 		xs->xattr_bh = NULL;
 		goto cleanup;
 	}
 	xs->not_found = ret;
 	return 0;
-
 cleanup:
 	brelse(blk_bh);
 
@@ -1941,6 +1989,18 @@ cleanup:
 	return ret;
 }
 
+static inline u32 ocfs2_xattr_hash_by_name(struct inode *inode,
+					   int name_index,
+					   const char *suffix_name)
+{
+	struct xattr_handler *handler = ocfs2_xattr_handler(name_index);
+	char *prefix = handler->prefix;
+	int prefix_len = strlen(handler->prefix);
+
+	return ocfs2_xattr_name_hash(inode, prefix, prefix_len,
+				     (char *)suffix_name, strlen(suffix_name));
+}
+
 /*
  * Find the xattr extent rec which may contains name_hash.
  * e_cpos will be the first name hash of the xattr rec.
@@ -2010,6 +2070,251 @@ typedef int (xattr_bucket_func)(struct inode *inode,
 				struct ocfs2_xattr_bucket *bucket,
 				void *para);
 
+static int ocfs2_find_xe_in_bucket(struct inode *inode,
+				   struct buffer_head *header_bh,
+				   int name_index,
+				   const char *name,
+				   u32 name_hash,
+				   u16 *xe_index,
+				   int *found)
+{
+	int i, ret = 0, cmp = 1, block_off, new_offset;
+	struct ocfs2_xattr_header *xh =
+			(struct ocfs2_xattr_header *)header_bh->b_data;
+	size_t name_len = strlen(name);
+	struct ocfs2_xattr_entry *xe = NULL;
+	struct buffer_head *name_bh = NULL;
+	char *xe_name;
+
+	/*
+	 * We don't use binary search in the bucket because there
+	 * may be multiple entries with the same name hash.
+	 */
+	for (i = 0; i < le16_to_cpu(xh->xh_count); i++) {
+		xe = &xh->xh_entries[i];
+
+		if (name_hash > le32_to_cpu(xe->xe_name_hash))
+			continue;
+		else if (name_hash < le32_to_cpu(xe->xe_name_hash))
+			break;
+
+		cmp = name_index - ocfs2_xattr_get_type(xe);
+		if (!cmp)
+			cmp = name_len - xe->xe_name_len;
+		if (cmp)
+			continue;
+
+		ret = ocfs2_xattr_bucket_get_name_value(inode,
+							xh,
+							i,
+							&block_off,
+							&new_offset);
+		if (ret) {
+			mlog_errno(ret);
+			break;
+		}
+
+		ret = ocfs2_read_block(OCFS2_SB(inode->i_sb),
+				       header_bh->b_blocknr + block_off,
+				       &name_bh, OCFS2_BH_CACHED, inode);
+		if (ret) {
+			mlog_errno(ret);
+			break;
+		}
+		xe_name = name_bh->b_data + new_offset;
+
+		cmp = memcmp(name, xe_name, name_len);
+		brelse(name_bh);
+		name_bh = NULL;
+
+		if (cmp == 0) {
+			*xe_index = i;
+			*found = 1;
+			ret = 0;
+			break;
+		}
+	}
+
+	return ret;
+}
+
+/*
+ * Find the specified xattr entry in a series of buckets.
+ * This series start from p_blkno and last for num_clusters.
+ * The ocfs2_xattr_header.xh_num_buckets of the first bucket contains
+ * the num of the valid buckets.
+ *
+ * Return the buffer_head this xattr should reside in. And if the xattr's
+ * hash is in the gap of 2 buckets, return the lower bucket.
+ */
+static int ocfs2_xattr_bucket_find(struct inode *inode,
+				   int name_index,
+				   const char *name,
+				   u32 name_hash,
+				   u64 p_blkno,
+				   u32 first_hash,
+				   u32 num_clusters,
+				   struct ocfs2_xattr_search *xs)
+{
+	int ret, found = 0;
+	struct buffer_head *bh = NULL;
+	struct buffer_head *lower_bh = NULL;
+	struct ocfs2_xattr_header *xh = NULL;
+	struct ocfs2_xattr_entry *xe = NULL;
+	u16 index = 0;
+	u16 blk_per_bucket = ocfs2_blocks_per_xattr_bucket(inode->i_sb);
+	int low_bucket = 0, bucket, high_bucket;
+	u32 last_hash;
+	u64 blkno;
+
+	ret = ocfs2_read_block(OCFS2_SB(inode->i_sb), p_blkno,
+			       &bh, OCFS2_BH_CACHED, inode);
+	if (ret) {
+		mlog_errno(ret);
+		goto out;
+	}
+
+	xh = (struct ocfs2_xattr_header *)bh->b_data;
+	high_bucket = le16_to_cpu(xh->xh_num_buckets) - 1;
+
+	while (low_bucket <= high_bucket) {
+		brelse(bh);
+		bh = NULL;
+		bucket = (low_bucket + high_bucket) / 2;
+
+		blkno = p_blkno + bucket * blk_per_bucket;
+
+		ret = ocfs2_read_block(OCFS2_SB(inode->i_sb), blkno,
+				       &bh, OCFS2_BH_CACHED, inode);
+		if (ret) {
+			mlog_errno(ret);
+			goto out;
+		}
+
+		xh = (struct ocfs2_xattr_header *)bh->b_data;
+		xe = &xh->xh_entries[0];
+		if (name_hash < le32_to_cpu(xe->xe_name_hash)) {
+			high_bucket = bucket - 1;
+			continue;
+		}
+
+		/*
+		 * Check whether the hash of the last entry in our
+		 * bucket is larger than the search one.
+		 */
+		xe = &xh->xh_entries[le16_to_cpu(xh->xh_count) - 1];
+		last_hash = le32_to_cpu(xe->xe_name_hash);
+
+		/* record lower_bh which may be the insert place. */
+		brelse(lower_bh);
+		lower_bh = bh;
+		bh = NULL;
+
+		if (name_hash > le32_to_cpu(xe->xe_name_hash)) {
+			low_bucket = bucket + 1;
+			continue;
+		}
+
+		/* the searched xattr should reside in this bucket if exists. */
+		ret = ocfs2_find_xe_in_bucket(inode, lower_bh,
+					      name_index, name, name_hash,
+					      &index, &found);
+		if (ret) {
+			mlog_errno(ret);
+			goto out;
+		}
+		break;
+	}
+
+	/*
+	 * Record the bucket we have found.
+	 * When the xattr's hash value is in the gap of 2 buckets, we will
+	 * always set it to the previous bucket.
+	 */
+	if (!lower_bh) {
+		/*
+		 * We can't find any bucket whose first name_hash is less
+		 * than the find name_hash.
+		 */
+		BUG_ON(bh->b_blocknr != p_blkno);
+		lower_bh = bh;
+		bh = NULL;
+	}
+	xs->bucket.bhs[0] = lower_bh;
+	xs->bucket.xh = (struct ocfs2_xattr_header *)
+					xs->bucket.bhs[0]->b_data;
+	lower_bh = NULL;
+
+	xs->header = xs->bucket.xh;
+	xs->base = xs->bucket.bhs[0]->b_data;
+	xs->end = xs->base + inode->i_sb->s_blocksize;
+
+	if (found) {
+		/*
+		 * If we have found the xattr enty, read all the blocks in
+		 * this bucket.
+		 */
+		ret = ocfs2_read_blocks(OCFS2_SB(inode->i_sb),
+					xs->bucket.bhs[0]->b_blocknr + 1,
+					blk_per_bucket - 1, &xs->bucket.bhs[1],
+					OCFS2_BH_CACHED, inode);
+		if (ret) {
+			mlog_errno(ret);
+			goto out;
+		}
+
+		xs->here = &xs->header->xh_entries[index];
+		mlog(0, "find xattr %s in bucket %llu, entry = %u\n", name,
+		     (unsigned long long)xs->bucket.bhs[0]->b_blocknr, index);
+	} else
+		ret = -ENODATA;
+
+out:
+	brelse(bh);
+	brelse(lower_bh);
+	return ret;
+}
+
+static int ocfs2_xattr_index_block_find(struct inode *inode,
+					struct buffer_head *root_bh,
+					int name_index,
+					const char *name,
+					struct ocfs2_xattr_search *xs)
+{
+	int ret;
+	struct ocfs2_xattr_block *xb =
+			(struct ocfs2_xattr_block *)root_bh->b_data;
+	struct ocfs2_xattr_tree_root *xb_root = &xb->xb_attrs.xb_root;
+	struct ocfs2_extent_list *el = &xb_root->xt_list;
+	u64 p_blkno = 0;
+	u32 first_hash, num_clusters = 0;
+	u32 name_hash = ocfs2_xattr_hash_by_name(inode, name_index, name);
+
+	if (le16_to_cpu(el->l_next_free_rec) == 0)
+		return -ENODATA;
+
+	mlog(0, "find xattr %s, hash = %u, index = %d in xattr tree\n",
+	     name, name_hash, name_index);
+
+	ret = ocfs2_xattr_get_rec(inode, name_hash, &p_blkno, &first_hash,
+				  &num_clusters, el);
+	if (ret) {
+		mlog_errno(ret);
+		goto out;
+	}
+
+	BUG_ON(p_blkno == 0 || num_clusters == 0 || first_hash > name_hash);
+
+	mlog(0, "find xattr extent rec %u clusters from %llu, the first hash "
+	     "in the rec is %u\n", num_clusters, p_blkno, first_hash);
+
+	ret = ocfs2_xattr_bucket_find(inode, name_index, name, name_hash,
+				      p_blkno, first_hash, num_clusters, xs);
+
+out:
+	return ret;
+}
+
 static int ocfs2_iterate_xattr_buckets(struct inode *inode,
 				       u64 blkno,
 				       u32 clusters,
-- 
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