[RFC,11/17] ubifs: repair: Build TNC

diff --git a/fs/ubifs/repair.c b/fs/ubifs/repair.c
index c43150fff19d..724f58510599 100644
--- a/fs/ubifs/repair.c
+++ b/fs/ubifs/repair.c
@@ -13,6 +13,7 @@ 
 
 #include <linux/module.h>
 #include <linux/crc32.h>
+#include <linux/list_sort.h>
 #include "ubifs.h"
 #include "repair.h"
 
@@ -30,6 +31,29 @@  struct scanned_info {
 	struct rb_root del_dents;
 };
 
+/**
+ * struct idx_entry - index entry.
+ * @list: link in the list index entries for building index tree
+ * @key: key
+ * @name: directory entry name used for sorting colliding keys by name
+ * @lnum: LEB number
+ * @offs: offset
+ * @len: length
+ *
+ * The index is recorded as a linked list which is sorted and used to create
+ * the bottom level of the on-flash index tree. The remaining levels of the
+ * index tree are each built from the level below.
+ */
+struct idx_entry {
+	struct list_head list;
+	union ubifs_key key;
+	char *name;
+	int name_len;
+	int lnum;
+	int offs;
+	int len;
+};
+
 static int init_repair_info(struct ubifs_info *c)
 {
 	int err;
@@ -324,6 +348,17 @@  static int parse_and_record_ino_node(struct ubifs_info *c, int lnum,
 	return 0;
 }
 
+static int namecmp(const char *a, int la, const char *b, int lb)
+{
+	int cmp, len = min(la, lb);
+
+	cmp = memcmp(a, b, len);
+	if (cmp)
+		return cmp;
+
+	return la - lb;
+}
+
 /**
  * insert_or_update_dent_node - insert or update dentry node.
  * @c: UBIFS file-system description object
@@ -338,7 +373,7 @@  static int insert_or_update_dent_node(struct ubifs_info *c,
 				      struct scanned_dent_node *new_dent,
 				      struct rb_root *tree)
 {
-	int cmp, nlen;
+	int cmp;
 	struct scanned_dent_node *dent_node, *old_dent_node = NULL;
 	struct rb_node **p, *parent = NULL;
 
@@ -352,9 +387,8 @@  static int insert_or_update_dent_node(struct ubifs_info *c,
 		} else if (cmp > 0) {
 			p = &(*p)->rb_right;
 		} else {
-			nlen = min(new_dent->nlen, dent_node->nlen);
-			cmp = strncmp(new_dent->name, dent_node->name, nlen) ? :
-				      new_dent->nlen - dent_node->nlen;
+			cmp = namecmp(new_dent->name, new_dent->nlen,
+				      dent_node->name, dent_node->nlen);
 			if (cmp < 0) {
 				p = &(*p)->rb_left;
 			} else if (cmp > 0) {
@@ -993,7 +1027,7 @@  static struct scanned_dent_node *
 lookup_valid_dent_node(struct ubifs_info *c, struct scanned_info *si,
 		       struct scanned_dent_node *target)
 {
-	int cmp, nlen;
+	int cmp;
 	struct scanned_dent_node *dent_node;
 	struct rb_node *p;
 
@@ -1006,9 +1040,8 @@  lookup_valid_dent_node(struct ubifs_info *c, struct scanned_info *si,
 		} else if (cmp > 0) {
 			p = p->rb_right;
 		} else {
-			nlen = min(target->nlen, dent_node->nlen);
-			cmp = strncmp(target->name, dent_node->name, nlen) ? :
-				      target->nlen - dent_node->nlen;
+			cmp = namecmp(target->name, target->nlen,
+				      dent_node->name, dent_node->nlen);
 			if (cmp < 0) {
 				p = p->rb_left;
 			} else if (cmp > 0) {
@@ -1754,6 +1787,27 @@  static int check_and_correct_files(struct ubifs_info *c)
 	return 0;
 }
 
+static int cmp_idx(void *priv, const struct list_head *a,
+		   const struct list_head *b)
+{
+	int cmp;
+	struct ubifs_info *c = priv;
+	struct idx_entry *ia, *ib;
+
+	cond_resched();
+	if (a == b)
+		return 0;
+
+	ia = list_entry(a, struct idx_entry, list);
+	ib = list_entry(b, struct idx_entry, list);
+
+	cmp = keys_cmp(c, &ia->key, &ib->key);
+	if (cmp)
+		return cmp;
+
+	return namecmp(ia->name, ia->name_len, ib->name, ib->name_len);
+}
+
 /**
  * get_free_leb - get a free LEB according to @c->repair->used_lebs.
  * @c: UBIFS file-system description object
@@ -1943,15 +1997,181 @@  static char *get_file_name(struct ubifs_info *c, struct scanned_file *file)
 	return name;
 }
 
-static void parse_node_location(struct ubifs_info *c, struct scanned_node *sn)
+static int parse_node_info(struct ubifs_info *c, struct scanned_node *sn,
+			   union ubifs_key *key, char *name, int name_len,
+			   struct list_head *idx_list, int *idx_cnt)
 {
 	int lnum, pos;
+	struct idx_entry *e;
 
 	lnum = sn->lnum - c->main_first;
 	pos = sn->offs + ALIGN(sn->len, 8);
 
 	set_bit(lnum, c->repair->used_lebs);
 	c->repair->lpts[lnum].end = max(c->repair->lpts[lnum].end, pos);
+
+	if (idx_cnt == NULL)
+		/* Skip truncation node. */
+		return 0;
+
+	e = kmalloc(sizeof(struct idx_entry), GFP_KERNEL);
+	if (!e)
+		return -ENOMEM;
+
+	key_copy(c, key, &e->key);
+	e->name = name;
+	e->name_len = name_len;
+	e->lnum = sn->lnum;
+	e->offs = sn->offs;
+	e->len = sn->len;
+	list_add_tail(&e->list, idx_list);
+	*idx_cnt = *idx_cnt + 1;
+
+	return 0;
+}
+
+static int add_idx_node(struct ubifs_info *c, struct ubifs_idx_node *idx,
+			union ubifs_key *key, int child_cnt,
+			struct idx_entry *e)
+{
+	int err, lnum, offs, len;
+
+	len = ubifs_idx_node_sz(c, child_cnt);
+	ubifs_prepare_node(c, idx, len, 0);
+
+	err = reserve_space(c, len, &lnum, &offs);
+	if (err)
+		return err;
+
+	copy_node_data(c, idx, offs, len);
+
+	c->calc_idx_sz += ALIGN(len, 8);
+
+	/* The last index node written will be the root */
+	c->zroot.lnum = lnum;
+	c->zroot.offs = offs;
+	c->zroot.len = len;
+
+	key_copy(c, key, &e->key);
+	e->lnum = lnum;
+	e->offs = offs;
+	e->len = len;
+
+	return err;
+}
+
+/**
+ * build_tnc - construct TNC and write it into flash.
+ * @c: UBIFS file-system description object
+ * @lower_idxs: leaf entries of TNC
+ * @lower_cnt: the count of @lower_idxs
+ *
+ * This function builds TNC according to @lower_idxs and writes all index
+ * nodes into flash.
+ */
+static int build_tnc(struct ubifs_info *c, struct list_head *lower_idxs,
+		     int lower_cnt)
+{
+	int i, j, err, upper_cnt, child_cnt, idx_sz, level = 0;
+	struct idx_entry *pe, *tmp_e, *e = NULL;
+	struct ubifs_idx_node *idx;
+	struct ubifs_branch *br;
+	union ubifs_key key;
+	LIST_HEAD(upper_idxs);
+
+	idx_sz = ubifs_idx_node_sz(c, c->fanout);
+	idx = kmalloc(idx_sz, GFP_KERNEL);
+	if (!idx)
+		return -ENOMEM;
+
+	list_sort(c, lower_idxs, cmp_idx);
+
+	ubifs_assert(c, lower_cnt != 0);
+
+	do {
+		upper_cnt = lower_cnt / c->fanout;
+		if (lower_cnt % c->fanout)
+			upper_cnt += 1;
+		e = list_first_entry(lower_idxs, struct idx_entry, list);
+
+		for (i = 0; i < upper_cnt; i++) {
+			if (fatal_signal_pending(current)) {
+				err = -EINTR;
+				goto out;
+			}
+			cond_resched();
+
+			if (i == upper_cnt - 1) {
+				child_cnt = lower_cnt % c->fanout;
+				if (child_cnt == 0)
+					child_cnt = c->fanout;
+			} else
+				child_cnt = c->fanout;
+
+			key_copy(c, &e->key, &key);
+			memset(idx, 0, idx_sz);
+			idx->ch.node_type = UBIFS_IDX_NODE;
+			idx->child_cnt = cpu_to_le16(child_cnt);
+			idx->level = cpu_to_le16(level);
+			for (j = 0; j < child_cnt; j++) {
+				ubifs_assert(c,
+				    !list_entry_is_head(e, lower_idxs, list));
+				br = ubifs_idx_branch(c, idx, j);
+				key_write_idx(c, &e->key, &br->key);
+				br->lnum = cpu_to_le32(e->lnum);
+				br->offs = cpu_to_le32(e->offs);
+				br->len = cpu_to_le32(e->len);
+				e = list_next_entry(e, list);
+			}
+
+			pe = kmalloc(sizeof(struct idx_entry), GFP_KERNEL);
+			if (!pe) {
+				err = -ENOMEM;
+				goto out;
+			}
+
+			err = add_idx_node(c, idx, &key, child_cnt, pe);
+			if (err) {
+				kfree(pe);
+				goto out;
+			}
+
+			list_add_tail(&pe->list, &upper_idxs);
+		}
+
+		level++;
+		list_for_each_entry_safe(e, tmp_e, lower_idxs, list) {
+			cond_resched();
+
+			list_del(&e->list);
+			kfree(e);
+		}
+		list_splice_init(&upper_idxs, lower_idxs);
+		lower_cnt = upper_cnt;
+	} while (lower_cnt > 1);
+
+	/* Set the index head */
+	c->ihead_lnum = c->repair->head_lnum;
+	c->ihead_offs = ALIGN(c->repair->head_offs, c->min_io_size);
+
+	/* Flush the last index LEB */
+	err = flush_write_buf(c);
+
+out:
+	list_for_each_entry_safe(e, tmp_e, lower_idxs, list) {
+		cond_resched();
+
+		list_del(&e->list);
+		kfree(e);
+	}
+	list_for_each_entry_safe(e, tmp_e, &upper_idxs, list) {
+		cond_resched();
+
+		list_del(&e->list);
+		kfree(e);
+	}
+	kfree(idx);
+	return err;
 }
 
 /**
@@ -1965,14 +2185,17 @@  static void parse_node_location(struct ubifs_info *c, struct scanned_node *sn)
  *    LEBs could be taken for storing new index tree.
  * 3. Re-write data to prevent failed gc scanning in the subsequent mounting
  *    process caused by corrupted data.
+ * 4. Build TNC.
  */
 static int traverse_files_and_nodes(struct ubifs_info *c)
 {
-	int i, err = 0;
+	int i, err = 0, idx_cnt = 0;
 	struct rb_node *node, *n;
 	struct scanned_file *file;
 	struct scanned_dent_node *dent_node;
 	struct scanned_data_node *data_node;
+	struct idx_entry *ie, *tmp_ie;
+	LIST_HEAD(idx_list);
 
 	if (rb_first(&c->repair->scanned_files) == NULL) {
 		/* No scanned files. Create root dir. */
@@ -1994,23 +2217,39 @@  static int traverse_files_and_nodes(struct ubifs_info *c)
 		     ubifs_get_type_name(ubifs_get_dent_type(file->ino.mode)),
 		     c->vi.ubi_num, c->vi.vol_id);
 
-		parse_node_location(c, &file->ino.header);
+		err = parse_node_info(c, &file->ino.header, &file->ino.key,
+				      NULL, 0, &idx_list, &idx_cnt);
+		if (err)
+			goto out_idx_list;
 
-		if (file->trun.header.exist)
-			parse_node_location(c, &file->trun.header);
+		if (file->trun.header.exist) {
+			err = parse_node_info(c, &file->trun.header, NULL, NULL,
+					      0, &idx_list, NULL);
+			if (err)
+				goto out_idx_list;
+		}
 
 		for (n = rb_first(&file->data_nodes); n; n = rb_next(n)) {
 			cond_resched();
 			data_node = rb_entry(n, struct scanned_data_node, rb);
 
-			parse_node_location(c, &data_node->header);
+			err = parse_node_info(c, &data_node->header,
+					      &data_node->key, NULL, 0,
+					      &idx_list, &idx_cnt);
+			if (err)
+				goto out_idx_list;
 		}
 
 		for (n = rb_first(&file->dent_nodes); n; n = rb_next(n)) {
 			cond_resched();
 			dent_node = rb_entry(n, struct scanned_dent_node, rb);
 
-			parse_node_location(c, &dent_node->header);
+			err = parse_node_info(c, &dent_node->header,
+					      &dent_node->key, dent_node->name,
+					      dent_node->nlen,
+					      &idx_list, &idx_cnt);
+			if (err)
+				goto out_idx_list;
 		}
 	}
 
@@ -2019,8 +2258,10 @@  static int traverse_files_and_nodes(struct ubifs_info *c)
 	for (i = 0; i < c->main_lebs; ++i) {
 		int lnum, len, end;
 
-		if (fatal_signal_pending(current))
-			return -EINTR;
+		if (fatal_signal_pending(current)) {
+			err = -EINTR;
+			goto out_idx_list;
+		}
 		cond_resched();
 
 		if (!test_bit(i, c->repair->used_lebs))
@@ -2035,16 +2276,27 @@  static int traverse_files_and_nodes(struct ubifs_info *c)
 
 		err = ubifs_leb_read(c, lnum, c->sbuf, 0, len, 0);
 		if (err && err != -EBADMSG)
-			return err;
+			goto out_idx_list;
 
 		if (len > end)
 			ubifs_pad(c, c->sbuf + end, len - end);
 
 		err = ubifs_leb_change(c, lnum, c->sbuf, len);
 		if (err)
-			return err;
+			goto out_idx_list;
 	}
 
+	/* Build TNC. */
+	ubifs_msg(c, "Step 10: Build TNC");
+	err = build_tnc(c, &idx_list, idx_cnt);
+
+out_idx_list:
+	list_for_each_entry_safe(ie, tmp_ie, &idx_list, list) {
+		cond_resched();
+
+		list_del(&ie->list);
+		kfree(ie);
+	}
 	return err;
 }
 
@@ -2088,6 +2340,7 @@  static int do_repair(struct ubifs_info *c)
 	/*
 	 * Step 8: Record used LEBs.
 	 * Step 9: Re-write data to clean corrupted data.
+	 * Step 10: Build TNC.
 	 */
 	err = traverse_files_and_nodes(c);