[bug report] f2fs: use rb_*_cached friends

[Dan Carpenter <dan.carpenter@oracle.com>]

Hello Chao Yu,

The patch df634f444ee9: "f2fs: use rb_*_cached friends" from Oct 4,
2018, leads to the following static checker warning:

	fs/f2fs/extent_cache.c:606 f2fs_update_extent_tree_range()
	error: uninitialized symbol 'leftmost'.

fs/f2fs/extent_cache.c
   497  static void f2fs_update_extent_tree_range(struct inode *inode,
   498                                  pgoff_t fofs, block_t blkaddr, unsigned int len)
   499  {
   500          struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
   501          struct extent_tree *et = F2FS_I(inode)->extent_tree;
   502          struct extent_node *en = NULL, *en1 = NULL;
   503          struct extent_node *prev_en = NULL, *next_en = NULL;
   504          struct extent_info ei, dei, prev;
   505          struct rb_node **insert_p = NULL, *insert_parent = NULL;
   506          unsigned int end = fofs + len;
   507          unsigned int pos = (unsigned int)fofs;
   508          bool updated = false;
   509          bool leftmost;
   510  
   511          if (!et)
   512                  return;
   513  
   514          trace_f2fs_update_extent_tree_range(inode, fofs, blkaddr, len);
   515  
   516          write_lock(&et->lock);
   517  
   518          if (is_inode_flag_set(inode, FI_NO_EXTENT)) {
   519                  write_unlock(&et->lock);
   520                  return;
   521          }
   522  
   523          prev = et->largest;
   524          dei.len = 0;
   525  
   526          /*
   527           * drop largest extent before lookup, in case it's already
   528           * been shrunk from extent tree
   529           */
   530          __drop_largest_extent(et, fofs, len);
   531  
   532          /* 1. lookup first extent node in range [fofs, fofs + len - 1] */
   533          en = (struct extent_node *)f2fs_lookup_rb_tree_ret(&et->root,
   534                                          (struct rb_entry *)et->cached_en, fofs,
   535                                          (struct rb_entry **)&prev_en,
   536                                          (struct rb_entry **)&next_en,
   537                                          &insert_p, &insert_parent, false,
   538                                          &leftmost);
                                                 ^^^^^^^^
Not always initialized in there.

   539          if (!en)
   540                  en = next_en;
   541  
   542          /* 2. invlidate all extent nodes in range [fofs, fofs + len - 1] */
   543          while (en && en->ei.fofs < end) {
   544                  unsigned int org_end;
   545                  int parts = 0;  /* # of parts current extent split into */
   546  
   547                  next_en = en1 = NULL;
   548  
   549                  dei = en->ei;
   550                  org_end = dei.fofs + dei.len;
   551                  f2fs_bug_on(sbi, pos >= org_end);
   552  
   553                  if (pos > dei.fofs &&   pos - dei.fofs >= F2FS_MIN_EXTENT_LEN) {
   554                          en->ei.len = pos - en->ei.fofs;
   555                          prev_en = en;
   556                          parts = 1;
   557                  }
   558  
   559                  if (end < org_end && org_end - end >= F2FS_MIN_EXTENT_LEN) {
   560                          if (parts) {
   561                                  set_extent_info(&ei, end,
   562                                                  end - dei.fofs + dei.blk,
   563                                                  org_end - end);
   564                                  en1 = __insert_extent_tree(sbi, et, &ei,
   565                                                          NULL, NULL, true);
   566                                  next_en = en1;
   567                          } else {
   568                                  en->ei.fofs = end;
   569                                  en->ei.blk += end - dei.fofs;
   570                                  en->ei.len -= end - dei.fofs;
   571                                  next_en = en;
   572                          }
   573                          parts++;
   574                  }
   575  
   576                  if (!next_en) {
   577                          struct rb_node *node = rb_next(&en->rb_node);
   578  
   579                          next_en = rb_entry_safe(node, struct extent_node,
   580                                                  rb_node);
   581                  }
   582  
   583                  if (parts)
   584                          __try_update_largest_extent(et, en);
   585                  else
   586                          __release_extent_node(sbi, et, en);
   587  
   588                  /*
   589                   * if original extent is split into zero or two parts, extent
   590                   * tree has been altered by deletion or insertion, therefore
   591                   * invalidate pointers regard to tree.
   592                   */
   593                  if (parts != 1) {
   594                          insert_p = NULL;
   595                          insert_parent = NULL;
   596                  }
   597                  en = next_en;
   598          }
   599  
   600          /* 3. update extent in extent cache */
   601          if (blkaddr) {
   602  
   603                  set_extent_info(&ei, fofs, blkaddr, len);
   604                  if (!__try_merge_extent_node(sbi, et, &ei, prev_en, next_en))
   605                          __insert_extent_tree(sbi, et, &ei,
   606                                          insert_p, insert_parent, leftmost);
                                                                         ^^^^^^^^
Smatch complains, but I'm to stupid to know if it's valid.

   607  
   608                  /* give up extent_cache, if split and small updates happen */
   609                  if (dei.len >= 1 &&
   610                                  prev.len < F2FS_MIN_EXTENT_LEN &&
   611                                  et->largest.len < F2FS_MIN_EXTENT_LEN) {
   612                          et->largest.len = 0;
   613                          et->largest_updated = true;
   614                          set_inode_flag(inode, FI_NO_EXTENT);
   615                  }
   616          }

regards,
dan carpenter