Linux-2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 2073 insertions, 0 deletions

diff --git a/fs/reiserfs/stree.c b/fs/reiserfs/stree.c
new file mode 100644
index 000000000000..73ec5212178b
--- /dev/null
+++ b/fs/reiserfs/stree.c
@@ -0,0 +1,2073 @@
+/*
+ *  Copyright 2000 by Hans Reiser, licensing governed by reiserfs/README
+ */
+
+/*
+ *  Written by Anatoly P. Pinchuk pap@namesys.botik.ru
+ *  Programm System Institute
+ *  Pereslavl-Zalessky Russia
+ */
+
+/*
+ *  This file contains functions dealing with S+tree
+ *
+ * B_IS_IN_TREE
+ * copy_item_head
+ * comp_short_keys
+ * comp_keys
+ * comp_short_le_keys
+ * le_key2cpu_key
+ * comp_le_keys
+ * bin_search
+ * get_lkey
+ * get_rkey
+ * key_in_buffer
+ * decrement_bcount
+ * decrement_counters_in_path
+ * reiserfs_check_path
+ * pathrelse_and_restore
+ * pathrelse
+ * search_by_key_reada
+ * search_by_key
+ * search_for_position_by_key
+ * comp_items
+ * prepare_for_direct_item
+ * prepare_for_direntry_item
+ * prepare_for_delete_or_cut
+ * calc_deleted_bytes_number
+ * init_tb_struct
+ * padd_item
+ * reiserfs_delete_item
+ * reiserfs_delete_solid_item
+ * reiserfs_delete_object
+ * maybe_indirect_to_direct
+ * indirect_to_direct_roll_back
+ * reiserfs_cut_from_item
+ * truncate_directory
+ * reiserfs_do_truncate
+ * reiserfs_paste_into_item
+ * reiserfs_insert_item
+ */
+
+#include <linux/config.h>
+#include <linux/time.h>
+#include <linux/string.h>
+#include <linux/pagemap.h>
+#include <linux/reiserfs_fs.h>
+#include <linux/smp_lock.h>
+#include <linux/buffer_head.h>
+#include <linux/quotaops.h>
+
+/* Does the buffer contain a disk block which is in the tree. */
+inline int B_IS_IN_TREE (const struct buffer_head * p_s_bh)
+{
+
+  RFALSE( B_LEVEL (p_s_bh) > MAX_HEIGHT,
+	  "PAP-1010: block (%b) has too big level (%z)", p_s_bh, p_s_bh);
+
+  return ( B_LEVEL (p_s_bh) != FREE_LEVEL );
+}
+
+//
+// to gets item head in le form
+//
+inline void copy_item_head(struct item_head * p_v_to, 
+			   const struct item_head * p_v_from)
+{
+  memcpy (p_v_to, p_v_from, IH_SIZE);
+}
+
+
+/* k1 is pointer to on-disk structure which is stored in little-endian
+   form. k2 is pointer to cpu variable. For key of items of the same
+   object this returns 0.
+   Returns: -1 if key1 < key2 
+   0 if key1 == key2
+   1 if key1 > key2 */
+inline int  comp_short_keys (const struct reiserfs_key * le_key,
+			     const struct cpu_key * cpu_key)
+{
+  __u32 * p_s_le_u32, * p_s_cpu_u32;
+  int n_key_length = REISERFS_SHORT_KEY_LEN;
+
+  p_s_le_u32 = (__u32 *)le_key;
+  p_s_cpu_u32 = (__u32 *)&cpu_key->on_disk_key;
+  for( ; n_key_length--; ++p_s_le_u32, ++p_s_cpu_u32 ) {
+    if ( le32_to_cpu (*p_s_le_u32) < *p_s_cpu_u32 )
+      return -1;
+    if ( le32_to_cpu (*p_s_le_u32) > *p_s_cpu_u32 )
+      return 1;
+  }
+
+  return 0;
+}
+
+
+/* k1 is pointer to on-disk structure which is stored in little-endian
+   form. k2 is pointer to cpu variable.
+   Compare keys using all 4 key fields.
+   Returns: -1 if key1 < key2 0
+   if key1 = key2 1 if key1 > key2 */
+static inline int  comp_keys (const struct reiserfs_key * le_key, const struct cpu_key * cpu_key)
+{
+  int retval;
+
+  retval = comp_short_keys (le_key, cpu_key);
+  if (retval)
+      return retval;
+  if (le_key_k_offset (le_key_version(le_key), le_key) < cpu_key_k_offset (cpu_key))
+      return -1;
+  if (le_key_k_offset (le_key_version(le_key), le_key) > cpu_key_k_offset (cpu_key))
+      return 1;
+
+  if (cpu_key->key_length == 3)
+      return 0;
+
+  /* this part is needed only when tail conversion is in progress */
+  if (le_key_k_type (le_key_version(le_key), le_key) < cpu_key_k_type (cpu_key))
+    return -1;
+
+  if (le_key_k_type (le_key_version(le_key), le_key) > cpu_key_k_type (cpu_key))
+    return 1;
+
+  return 0;
+}
+
+
+inline int comp_short_le_keys (const struct reiserfs_key * key1, const struct reiserfs_key * key2)
+{
+  __u32 * p_s_1_u32, * p_s_2_u32;
+  int n_key_length = REISERFS_SHORT_KEY_LEN;
+
+  p_s_1_u32 = (__u32 *)key1;
+  p_s_2_u32 = (__u32 *)key2;
+  for( ; n_key_length--; ++p_s_1_u32, ++p_s_2_u32 ) {
+    if ( le32_to_cpu (*p_s_1_u32) < le32_to_cpu (*p_s_2_u32) )
+      return -1;
+    if ( le32_to_cpu (*p_s_1_u32) > le32_to_cpu (*p_s_2_u32) )
+      return 1;
+  }
+  return 0;
+}
+
+inline void le_key2cpu_key (struct cpu_key * to, const struct reiserfs_key * from)
+{
+    to->on_disk_key.k_dir_id = le32_to_cpu (from->k_dir_id);
+    to->on_disk_key.k_objectid = le32_to_cpu (from->k_objectid);
+    
+    // find out version of the key
+    to->version = le_key_version (from);
+    if (to->version == KEY_FORMAT_3_5) {
+	to->on_disk_key.u.k_offset_v1.k_offset = le32_to_cpu (from->u.k_offset_v1.k_offset);
+	to->on_disk_key.u.k_offset_v1.k_uniqueness = le32_to_cpu (from->u.k_offset_v1.k_uniqueness);
+    } else {
+	to->on_disk_key.u.k_offset_v2.k_offset = offset_v2_k_offset(&from->u.k_offset_v2);
+	to->on_disk_key.u.k_offset_v2.k_type = offset_v2_k_type(&from->u.k_offset_v2);
+    } 
+}
+
+
+
+// this does not say which one is bigger, it only returns 1 if keys
+// are not equal, 0 otherwise
+inline int comp_le_keys (const struct reiserfs_key * k1, const struct reiserfs_key * k2)
+{
+    return memcmp (k1, k2, sizeof (struct reiserfs_key));
+}
+
+/**************************************************************************
+ *  Binary search toolkit function                                        *
+ *  Search for an item in the array by the item key                       *
+ *  Returns:    1 if found,  0 if not found;                              *
+ *        *p_n_pos = number of the searched element if found, else the    *
+ *        number of the first element that is larger than p_v_key.        *
+ **************************************************************************/
+/* For those not familiar with binary search: n_lbound is the leftmost item that it
+ could be, n_rbound the rightmost item that it could be.  We examine the item
+ halfway between n_lbound and n_rbound, and that tells us either that we can increase
+ n_lbound, or decrease n_rbound, or that we have found it, or if n_lbound <= n_rbound that
+ there are no possible items, and we have not found it. With each examination we
+ cut the number of possible items it could be by one more than half rounded down,
+ or we find it. */
+static inline	int bin_search (
+              const void * p_v_key, /* Key to search for.                   */
+	      const void * p_v_base,/* First item in the array.             */
+	      int       p_n_num,    /* Number of items in the array.        */
+	      int       p_n_width,  /* Item size in the array.
+				       searched. Lest the reader be
+				       confused, note that this is crafted
+				       as a general function, and when it
+				       is applied specifically to the array
+				       of item headers in a node, p_n_width
+				       is actually the item header size not
+				       the item size.                      */
+	      int     * p_n_pos     /* Number of the searched for element. */
+            ) {
+    int   n_rbound, n_lbound, n_j;
+
+   for ( n_j = ((n_rbound = p_n_num - 1) + (n_lbound = 0))/2; n_lbound <= n_rbound; n_j = (n_rbound + n_lbound)/2 )
+     switch( comp_keys((struct reiserfs_key *)((char * )p_v_base + n_j * p_n_width), (struct cpu_key *)p_v_key) )  {
+     case -1: n_lbound = n_j + 1; continue;
+     case  1: n_rbound = n_j - 1; continue;
+     case  0: *p_n_pos = n_j;     return ITEM_FOUND; /* Key found in the array.  */
+        }
+
+    /* bin_search did not find given key, it returns position of key,
+        that is minimal and greater than the given one. */
+    *p_n_pos = n_lbound;
+    return ITEM_NOT_FOUND;
+}
+
+#ifdef CONFIG_REISERFS_CHECK
+extern struct tree_balance * cur_tb;
+#endif
+
+
+
+/* Minimal possible key. It is never in the tree. */
+const struct reiserfs_key  MIN_KEY = {0, 0, {{0, 0},}};
+
+/* Maximal possible key. It is never in the tree. */
+const struct reiserfs_key  MAX_KEY = {0xffffffff, 0xffffffff, {{0xffffffff, 0xffffffff},}};
+
+
+/* Get delimiting key of the buffer by looking for it in the buffers in the path, starting from the bottom
+   of the path, and going upwards.  We must check the path's validity at each step.  If the key is not in
+   the path, there is no delimiting key in the tree (buffer is first or last buffer in tree), and in this
+   case we return a special key, either MIN_KEY or MAX_KEY. */
+static inline	const struct  reiserfs_key * get_lkey  (
+	                const struct path         * p_s_chk_path,
+                        const struct super_block  * p_s_sb
+                      ) {
+  int                   n_position, n_path_offset = p_s_chk_path->path_length;
+  struct buffer_head  * p_s_parent;
+  
+  RFALSE( n_path_offset < FIRST_PATH_ELEMENT_OFFSET, 
+	  "PAP-5010: invalid offset in the path");
+
+  /* While not higher in path than first element. */
+  while ( n_path_offset-- > FIRST_PATH_ELEMENT_OFFSET ) {
+
+    RFALSE( ! buffer_uptodate(PATH_OFFSET_PBUFFER(p_s_chk_path, n_path_offset)),
+	    "PAP-5020: parent is not uptodate");
+
+    /* Parent at the path is not in the tree now. */
+    if ( ! B_IS_IN_TREE(p_s_parent = PATH_OFFSET_PBUFFER(p_s_chk_path, n_path_offset)) )
+      return &MAX_KEY;
+    /* Check whether position in the parent is correct. */
+    if ( (n_position = PATH_OFFSET_POSITION(p_s_chk_path, n_path_offset)) > B_NR_ITEMS(p_s_parent) )
+       return &MAX_KEY;
+    /* Check whether parent at the path really points to the child. */
+    if ( B_N_CHILD_NUM(p_s_parent, n_position) !=
+	 PATH_OFFSET_PBUFFER(p_s_chk_path, n_path_offset + 1)->b_blocknr )
+      return &MAX_KEY;
+    /* Return delimiting key if position in the parent is not equal to zero. */
+    if ( n_position )
+      return B_N_PDELIM_KEY(p_s_parent, n_position - 1);
+  }
+  /* Return MIN_KEY if we are in the root of the buffer tree. */
+  if ( PATH_OFFSET_PBUFFER(p_s_chk_path, FIRST_PATH_ELEMENT_OFFSET)->b_blocknr ==
+       SB_ROOT_BLOCK (p_s_sb) )
+    return &MIN_KEY;
+  return  &MAX_KEY;
+}
+
+
+/* Get delimiting key of the buffer at the path and its right neighbor. */
+inline	const struct  reiserfs_key * get_rkey  (
+	                const struct path         * p_s_chk_path,
+                        const struct super_block  * p_s_sb
+                      ) {
+  int                   n_position,
+    			n_path_offset = p_s_chk_path->path_length;
+  struct buffer_head  * p_s_parent;
+
+  RFALSE( n_path_offset < FIRST_PATH_ELEMENT_OFFSET,
+	  "PAP-5030: invalid offset in the path");
+
+  while ( n_path_offset-- > FIRST_PATH_ELEMENT_OFFSET ) {
+
+    RFALSE( ! buffer_uptodate(PATH_OFFSET_PBUFFER(p_s_chk_path, n_path_offset)),
+	    "PAP-5040: parent is not uptodate");
+
+    /* Parent at the path is not in the tree now. */
+    if ( ! B_IS_IN_TREE(p_s_parent = PATH_OFFSET_PBUFFER(p_s_chk_path, n_path_offset)) )
+      return &MIN_KEY;
+    /* Check whether position in the parent is correct. */
+    if ( (n_position = PATH_OFFSET_POSITION(p_s_chk_path, n_path_offset)) > B_NR_ITEMS(p_s_parent) )
+      return &MIN_KEY;
+    /* Check whether parent at the path really points to the child. */
+    if ( B_N_CHILD_NUM(p_s_parent, n_position) !=
+                                        PATH_OFFSET_PBUFFER(p_s_chk_path, n_path_offset + 1)->b_blocknr )
+      return &MIN_KEY;
+    /* Return delimiting key if position in the parent is not the last one. */
+    if ( n_position != B_NR_ITEMS(p_s_parent) )
+      return B_N_PDELIM_KEY(p_s_parent, n_position);
+  }
+  /* Return MAX_KEY if we are in the root of the buffer tree. */
+  if ( PATH_OFFSET_PBUFFER(p_s_chk_path, FIRST_PATH_ELEMENT_OFFSET)->b_blocknr ==
+       SB_ROOT_BLOCK (p_s_sb) )
+    return &MAX_KEY;
+  return  &MIN_KEY;
+}
+
+
+/* Check whether a key is contained in the tree rooted from a buffer at a path. */
+/* This works by looking at the left and right delimiting keys for the buffer in the last path_element in
+   the path.  These delimiting keys are stored at least one level above that buffer in the tree. If the
+   buffer is the first or last node in the tree order then one of the delimiting keys may be absent, and in
+   this case get_lkey and get_rkey return a special key which is MIN_KEY or MAX_KEY. */
+static  inline  int key_in_buffer (
+                      struct path         * p_s_chk_path, /* Path which should be checked.  */
+                      const struct cpu_key      * p_s_key,      /* Key which should be checked.   */
+                      struct super_block  * p_s_sb        /* Super block pointer.           */
+		      ) {
+
+  RFALSE( ! p_s_key || p_s_chk_path->path_length < FIRST_PATH_ELEMENT_OFFSET ||
+	  p_s_chk_path->path_length > MAX_HEIGHT,
+	  "PAP-5050: pointer to the key(%p) is NULL or invalid path length(%d)",
+	  p_s_key, p_s_chk_path->path_length);
+  RFALSE( !PATH_PLAST_BUFFER(p_s_chk_path)->b_bdev,
+	  "PAP-5060: device must not be NODEV");
+
+  if ( comp_keys(get_lkey(p_s_chk_path, p_s_sb), p_s_key) == 1 )
+    /* left delimiting key is bigger, that the key we look for */
+    return 0;
+  //  if ( comp_keys(p_s_key, get_rkey(p_s_chk_path, p_s_sb)) != -1 )
+  if ( comp_keys(get_rkey(p_s_chk_path, p_s_sb), p_s_key) != 1 )
+    /* p_s_key must be less than right delimitiing key */
+    return 0;
+  return 1;
+}
+
+
+inline void decrement_bcount(
+              struct buffer_head  * p_s_bh
+            ) { 
+  if ( p_s_bh ) {
+    if ( atomic_read (&(p_s_bh->b_count)) ) {
+      put_bh(p_s_bh) ;
+      return;
+    }
+    reiserfs_panic(NULL, "PAP-5070: decrement_bcount: trying to free free buffer %b", p_s_bh);
+  }
+}
+
+
+/* Decrement b_count field of the all buffers in the path. */
+void decrement_counters_in_path (
+              struct path * p_s_search_path
+            ) {
+  int n_path_offset = p_s_search_path->path_length;
+
+  RFALSE( n_path_offset < ILLEGAL_PATH_ELEMENT_OFFSET ||
+	  n_path_offset > EXTENDED_MAX_HEIGHT - 1,
+	  "PAP-5080: invalid path offset of %d", n_path_offset);
+
+  while ( n_path_offset > ILLEGAL_PATH_ELEMENT_OFFSET ) {
+    struct buffer_head * bh;
+
+    bh = PATH_OFFSET_PBUFFER(p_s_search_path, n_path_offset--);
+    decrement_bcount (bh);
+  }
+  p_s_search_path->path_length = ILLEGAL_PATH_ELEMENT_OFFSET;
+}
+
+
+int reiserfs_check_path(struct path *p) {
+  RFALSE( p->path_length != ILLEGAL_PATH_ELEMENT_OFFSET,
+	  "path not properly relsed") ;
+  return 0 ;
+}
+
+
+/* Release all buffers in the path. Restore dirty bits clean
+** when preparing the buffer for the log
+**
+** only called from fix_nodes()
+*/
+void  pathrelse_and_restore (
+	struct super_block *s, 
+        struct path * p_s_search_path
+      ) {
+  int n_path_offset = p_s_search_path->path_length;
+
+  RFALSE( n_path_offset < ILLEGAL_PATH_ELEMENT_OFFSET, 
+	  "clm-4000: invalid path offset");
+  
+  while ( n_path_offset > ILLEGAL_PATH_ELEMENT_OFFSET )  {
+    reiserfs_restore_prepared_buffer(s, PATH_OFFSET_PBUFFER(p_s_search_path, 
+                                     n_path_offset));
+    brelse(PATH_OFFSET_PBUFFER(p_s_search_path, n_path_offset--));
+  }
+  p_s_search_path->path_length = ILLEGAL_PATH_ELEMENT_OFFSET;
+}
+
+/* Release all buffers in the path. */
+void  pathrelse (
+        struct path * p_s_search_path
+      ) {
+  int n_path_offset = p_s_search_path->path_length;
+
+  RFALSE( n_path_offset < ILLEGAL_PATH_ELEMENT_OFFSET,
+	  "PAP-5090: invalid path offset");
+  
+  while ( n_path_offset > ILLEGAL_PATH_ELEMENT_OFFSET )  
+    brelse(PATH_OFFSET_PBUFFER(p_s_search_path, n_path_offset--));
+
+  p_s_search_path->path_length = ILLEGAL_PATH_ELEMENT_OFFSET;
+}
+
+
+
+static int is_leaf (char * buf, int blocksize, struct buffer_head * bh)
+{
+    struct block_head * blkh;
+    struct item_head * ih;
+    int used_space;
+    int prev_location;
+    int i;
+    int nr;
+
+    blkh = (struct block_head *)buf;
+    if ( blkh_level(blkh) != DISK_LEAF_NODE_LEVEL) {
+	reiserfs_warning (NULL, "is_leaf: this should be caught earlier");
+	return 0;
+    }
+
+    nr = blkh_nr_item(blkh);
+    if (nr < 1 || nr > ((blocksize - BLKH_SIZE) / (IH_SIZE + MIN_ITEM_LEN))) {
+	/* item number is too big or too small */
+	reiserfs_warning (NULL, "is_leaf: nr_item seems wrong: %z", bh);
+	return 0;
+    }
+    ih = (struct item_head *)(buf + BLKH_SIZE) + nr - 1;
+    used_space = BLKH_SIZE + IH_SIZE * nr + (blocksize - ih_location (ih));
+    if (used_space != blocksize - blkh_free_space(blkh)) {
+	/* free space does not match to calculated amount of use space */
+	reiserfs_warning (NULL, "is_leaf: free space seems wrong: %z", bh);
+	return 0;
+    }
+
+    // FIXME: it is_leaf will hit performance too much - we may have
+    // return 1 here
+
+    /* check tables of item heads */
+    ih = (struct item_head *)(buf + BLKH_SIZE);
+    prev_location = blocksize;
+    for (i = 0; i < nr; i ++, ih ++) {
+	if ( le_ih_k_type(ih) == TYPE_ANY) {
+	    reiserfs_warning (NULL, "is_leaf: wrong item type for item %h",ih);
+	    return 0;
+	}
+	if (ih_location (ih) >= blocksize || ih_location (ih) < IH_SIZE * nr) {
+	    reiserfs_warning (NULL, "is_leaf: item location seems wrong: %h", ih);
+	    return 0;
+	}
+	if (ih_item_len (ih) < 1 || ih_item_len (ih) > MAX_ITEM_LEN (blocksize)) {
+	    reiserfs_warning (NULL, "is_leaf: item length seems wrong: %h", ih);
+	    return 0;
+	}
+	if (prev_location - ih_location (ih) != ih_item_len (ih)) {
+	    reiserfs_warning (NULL, "is_leaf: item location seems wrong (second one): %h", ih);
+	    return 0;
+	}
+	prev_location = ih_location (ih);
+    }
+
+    // one may imagine much more checks
+    return 1;
+}
+
+
+/* returns 1 if buf looks like an internal node, 0 otherwise */
+static int is_internal (char * buf, int blocksize, struct buffer_head * bh)
+{
+    struct block_head * blkh;
+    int nr;
+    int used_space;
+
+    blkh = (struct block_head *)buf;
+    nr = blkh_level(blkh);
+    if (nr <= DISK_LEAF_NODE_LEVEL || nr > MAX_HEIGHT) {
+	/* this level is not possible for internal nodes */
+	reiserfs_warning (NULL, "is_internal: this should be caught earlier");
+	return 0;
+    }
+    
+    nr = blkh_nr_item(blkh);
+    if (nr > (blocksize - BLKH_SIZE - DC_SIZE) / (KEY_SIZE + DC_SIZE)) {
+	/* for internal which is not root we might check min number of keys */
+	reiserfs_warning (NULL, "is_internal: number of key seems wrong: %z", bh);
+	return 0;
+    }
+
+    used_space = BLKH_SIZE + KEY_SIZE * nr + DC_SIZE * (nr + 1);
+    if (used_space != blocksize - blkh_free_space(blkh)) {
+	reiserfs_warning (NULL, "is_internal: free space seems wrong: %z", bh);
+	return 0;
+    }
+
+    // one may imagine much more checks
+    return 1;
+}
+
+
+// make sure that bh contains formatted node of reiserfs tree of
+// 'level'-th level
+static int is_tree_node (struct buffer_head * bh, int level)
+{
+    if (B_LEVEL (bh) != level) {
+	reiserfs_warning (NULL, "is_tree_node: node level %d does not match to the expected one %d",
+		B_LEVEL (bh), level);
+	return 0;
+    }
+    if (level == DISK_LEAF_NODE_LEVEL)
+	return is_leaf (bh->b_data, bh->b_size, bh);
+
+    return is_internal (bh->b_data, bh->b_size, bh);
+}
+
+
+
+#define SEARCH_BY_KEY_READA 16
+
+/* The function is NOT SCHEDULE-SAFE! */
+static void search_by_key_reada (struct super_block * s,
+                                 struct buffer_head **bh,
+				 unsigned long *b, int num)
+{
+    int i,j;
+  
+    for (i = 0 ; i < num ; i++) {
+	bh[i] = sb_getblk (s, b[i]);
+    }
+    for (j = 0 ; j < i ; j++) {
+	/*
+	 * note, this needs attention if we are getting rid of the BKL
+	 * you have to make sure the prepared bit isn't set on this buffer
+	 */
+	if (!buffer_uptodate(bh[j]))
+	    ll_rw_block(READA, 1, bh + j);
+    	brelse(bh[j]);
+    }
+}
+
+/**************************************************************************
+ * Algorithm   SearchByKey                                                *
+ *             look for item in the Disk S+Tree by its key                *
+ * Input:  p_s_sb   -  super block                                        *
+ *         p_s_key  - pointer to the key to search                        *
+ * Output: ITEM_FOUND, ITEM_NOT_FOUND or IO_ERROR                         *
+ *         p_s_search_path - path from the root to the needed leaf        *
+ **************************************************************************/
+
+/* This function fills up the path from the root to the leaf as it
+   descends the tree looking for the key.  It uses reiserfs_bread to
+   try to find buffers in the cache given their block number.  If it
+   does not find them in the cache it reads them from disk.  For each
+   node search_by_key finds using reiserfs_bread it then uses
+   bin_search to look through that node.  bin_search will find the
+   position of the block_number of the next node if it is looking
+   through an internal node.  If it is looking through a leaf node
+   bin_search will find the position of the item which has key either
+   equal to given key, or which is the maximal key less than the given
+   key.  search_by_key returns a path that must be checked for the
+   correctness of the top of the path but need not be checked for the
+   correctness of the bottom of the path */
+/* The function is NOT SCHEDULE-SAFE! */
+int search_by_key (struct super_block * p_s_sb,
+		   const struct cpu_key * p_s_key, /* Key to search. */
+		   struct path * p_s_search_path, /* This structure was
+						     allocated and initialized
+						     by the calling
+						     function. It is filled up
+						     by this function.  */
+		   int n_stop_level /* How far down the tree to search. To
+                                       stop at leaf level - set to
+                                       DISK_LEAF_NODE_LEVEL */
+    ) {
+    int  n_block_number;
+    int  expected_level;
+    struct buffer_head  *       p_s_bh;
+    struct path_element *       p_s_last_element;
+    int				n_node_level, n_retval;
+    int 			right_neighbor_of_leaf_node;
+    int				fs_gen;
+    struct buffer_head *reada_bh[SEARCH_BY_KEY_READA];
+    unsigned long      reada_blocks[SEARCH_BY_KEY_READA];
+    int reada_count = 0;
+
+#ifdef CONFIG_REISERFS_CHECK
+    int n_repeat_counter = 0;
+#endif
+    
+    PROC_INFO_INC( p_s_sb, search_by_key );
+    
+    /* As we add each node to a path we increase its count.  This means that
+       we must be careful to release all nodes in a path before we either
+       discard the path struct or re-use the path struct, as we do here. */
+
+    decrement_counters_in_path(p_s_search_path);
+
+    right_neighbor_of_leaf_node = 0;
+
+    /* With each iteration of this loop we search through the items in the
+       current node, and calculate the next current node(next path element)
+       for the next iteration of this loop.. */
+    n_block_number = SB_ROOT_BLOCK (p_s_sb);
+    expected_level = -1;
+    while ( 1 ) {
+
+#ifdef CONFIG_REISERFS_CHECK
+	if ( !(++n_repeat_counter % 50000) )
+	    reiserfs_warning (p_s_sb, "PAP-5100: search_by_key: %s:"
+			      "there were %d iterations of while loop "
+			      "looking for key %K",
+			      current->comm, n_repeat_counter, p_s_key);
+#endif
+
+	/* prep path to have another element added to it. */
+	p_s_last_element = PATH_OFFSET_PELEMENT(p_s_search_path, ++p_s_search_path->path_length);
+	fs_gen = get_generation (p_s_sb);
+
+	/* Read the next tree node, and set the last element in the path to
+           have a pointer to it. */
+	if ((p_s_bh = p_s_last_element->pe_buffer =
+	     sb_getblk(p_s_sb, n_block_number)) ) {
+	    if (!buffer_uptodate(p_s_bh) && reada_count > 1) {
+		search_by_key_reada (p_s_sb, reada_bh,
+		                     reada_blocks, reada_count);
+	    }
+	    ll_rw_block(READ, 1, &p_s_bh);
+	    wait_on_buffer(p_s_bh);
+	    if (!buffer_uptodate(p_s_bh))
+	        goto io_error;
+	} else {
+io_error:
+	    p_s_search_path->path_length --;
+	    pathrelse(p_s_search_path);
+	    return IO_ERROR;
+	}
+	reada_count = 0;
+	if (expected_level == -1)
+		expected_level = SB_TREE_HEIGHT (p_s_sb);
+	expected_level --;
+
+	/* It is possible that schedule occurred. We must check whether the key
+	   to search is still in the tree rooted from the current buffer. If
+	   not then repeat search from the root. */
+	if ( fs_changed (fs_gen, p_s_sb) && 
+	    (!B_IS_IN_TREE (p_s_bh) ||
+	     B_LEVEL(p_s_bh) != expected_level ||
+	     !key_in_buffer(p_s_search_path, p_s_key, p_s_sb))) {
+	    PROC_INFO_INC( p_s_sb, search_by_key_fs_changed );
+	    PROC_INFO_INC( p_s_sb, search_by_key_restarted );
+	    PROC_INFO_INC( p_s_sb, sbk_restarted[ expected_level - 1 ] );
+	    decrement_counters_in_path(p_s_search_path);
+	    
+	    /* Get the root block number so that we can repeat the search
+	       starting from the root. */
+	    n_block_number = SB_ROOT_BLOCK (p_s_sb);
+	    expected_level = -1;
+	    right_neighbor_of_leaf_node = 0;
+	    
+	    /* repeat search from the root */
+	    continue;
+	}
+
+        /* only check that the key is in the buffer if p_s_key is not
+           equal to the MAX_KEY. Latter case is only possible in
+           "finish_unfinished()" processing during mount. */
+        RFALSE( comp_keys( &MAX_KEY, p_s_key ) &&
+                ! key_in_buffer(p_s_search_path, p_s_key, p_s_sb),
+		"PAP-5130: key is not in the buffer");
+#ifdef CONFIG_REISERFS_CHECK
+	if ( cur_tb ) {
+	    print_cur_tb ("5140");
+	    reiserfs_panic(p_s_sb, "PAP-5140: search_by_key: schedule occurred in do_balance!");
+	}
+#endif
+
+	// make sure, that the node contents look like a node of
+	// certain level
+	if (!is_tree_node (p_s_bh, expected_level)) {
+	    reiserfs_warning (p_s_sb, "vs-5150: search_by_key: "
+			      "invalid format found in block %ld. Fsck?",
+			      p_s_bh->b_blocknr);
+	    pathrelse (p_s_search_path);
+	    return IO_ERROR;
+	}
+	
+	/* ok, we have acquired next formatted node in the tree */
+	n_node_level = B_LEVEL (p_s_bh);
+
+	PROC_INFO_BH_STAT( p_s_sb, p_s_bh, n_node_level - 1 );
+
+	RFALSE( n_node_level < n_stop_level,
+		"vs-5152: tree level (%d) is less than stop level (%d)",
+		n_node_level, n_stop_level);
+
+	n_retval = bin_search( p_s_key, B_N_PITEM_HEAD(p_s_bh, 0),
+                B_NR_ITEMS(p_s_bh),
+                ( n_node_level == DISK_LEAF_NODE_LEVEL ) ? IH_SIZE : KEY_SIZE,
+                &(p_s_last_element->pe_position));
+	if (n_node_level == n_stop_level) {
+	    return n_retval;
+	}
+
+	/* we are not in the stop level */
+	if (n_retval == ITEM_FOUND)
+	    /* item has been found, so we choose the pointer which is to the right of the found one */
+	    p_s_last_element->pe_position++;
+
+	/* if item was not found we choose the position which is to
+	   the left of the found item. This requires no code,
+	   bin_search did it already.*/
+
+	/* So we have chosen a position in the current node which is
+	   an internal node.  Now we calculate child block number by
+	   position in the node. */
+	n_block_number = B_N_CHILD_NUM(p_s_bh, p_s_last_element->pe_position);
+
+	/* if we are going to read leaf nodes, try for read ahead as well */
+	if ((p_s_search_path->reada & PATH_READA) &&
+	    n_node_level == DISK_LEAF_NODE_LEVEL + 1)
+	{
+	    int pos = p_s_last_element->pe_position;
+	    int limit = B_NR_ITEMS(p_s_bh);
+	    struct reiserfs_key *le_key;
+
+	    if (p_s_search_path->reada & PATH_READA_BACK)
+		limit = 0;
+	    while(reada_count < SEARCH_BY_KEY_READA) {
+		if (pos == limit)
+		    break;
+	        reada_blocks[reada_count++] = B_N_CHILD_NUM(p_s_bh, pos);
+		if (p_s_search_path->reada & PATH_READA_BACK)
+		    pos--;
+		else
+		    pos++;
+
+		/*
+		 * check to make sure we're in the same object
+		 */
+		le_key = B_N_PDELIM_KEY(p_s_bh, pos);
+		if (le32_to_cpu(le_key->k_objectid) !=
+		    p_s_key->on_disk_key.k_objectid)
+		{
+		    break;
+		}
+	    }
+        }
+    }
+}
+
+
+/* Form the path to an item and position in this item which contains
+   file byte defined by p_s_key. If there is no such item
+   corresponding to the key, we point the path to the item with
+   maximal key less than p_s_key, and *p_n_pos_in_item is set to one
+   past the last entry/byte in the item.  If searching for entry in a
+   directory item, and it is not found, *p_n_pos_in_item is set to one
+   entry more than the entry with maximal key which is less than the
+   sought key.
+
+   Note that if there is no entry in this same node which is one more,
+   then we point to an imaginary entry.  for direct items, the
+   position is in units of bytes, for indirect items the position is
+   in units of blocknr entries, for directory items the position is in
+   units of directory entries.  */
+
+/* The function is NOT SCHEDULE-SAFE! */
+int search_for_position_by_key (struct super_block  * p_s_sb,         /* Pointer to the super block.          */
+				const struct cpu_key  * p_cpu_key,      /* Key to search (cpu variable)         */
+				struct path         * p_s_search_path /* Filled up by this function.          */
+    ) {
+    struct item_head    * p_le_ih; /* pointer to on-disk structure */
+    int                   n_blk_size;
+    loff_t item_offset, offset;
+    struct reiserfs_dir_entry de;
+    int retval;
+
+    /* If searching for directory entry. */
+    if ( is_direntry_cpu_key (p_cpu_key) )
+	return  search_by_entry_key (p_s_sb, p_cpu_key, p_s_search_path, &de);
+
+    /* If not searching for directory entry. */
+    
+    /* If item is found. */
+    retval = search_item (p_s_sb, p_cpu_key, p_s_search_path);
+    if (retval == IO_ERROR)
+	return retval;
+    if ( retval == ITEM_FOUND )  {
+
+	RFALSE( ! ih_item_len(
+                B_N_PITEM_HEAD(PATH_PLAST_BUFFER(p_s_search_path),
+			       PATH_LAST_POSITION(p_s_search_path))),
+	        "PAP-5165: item length equals zero");
+
+	pos_in_item(p_s_search_path) = 0;
+	return POSITION_FOUND;
+    }
+
+    RFALSE( ! PATH_LAST_POSITION(p_s_search_path),
+	    "PAP-5170: position equals zero");
+
+    /* Item is not found. Set path to the previous item. */
+    p_le_ih = B_N_PITEM_HEAD(PATH_PLAST_BUFFER(p_s_search_path), --PATH_LAST_POSITION(p_s_search_path));
+    n_blk_size = p_s_sb->s_blocksize;
+
+    if (comp_short_keys (&(p_le_ih->ih_key), p_cpu_key)) {
+	return FILE_NOT_FOUND;
+    }
+
+    // FIXME: quite ugly this far
+
+    item_offset = le_ih_k_offset (p_le_ih);
+    offset = cpu_key_k_offset (p_cpu_key);
+
+    /* Needed byte is contained in the item pointed to by the path.*/
+    if (item_offset <= offset &&
+	item_offset + op_bytes_number (p_le_ih, n_blk_size) > offset) {
+	pos_in_item (p_s_search_path) = offset - item_offset;
+	if ( is_indirect_le_ih(p_le_ih) ) {
+	    pos_in_item (p_s_search_path) /= n_blk_size;
+	}
+	return POSITION_FOUND;
+    }
+
+    /* Needed byte is not contained in the item pointed to by the
+     path. Set pos_in_item out of the item. */
+    if ( is_indirect_le_ih (p_le_ih) )
+	pos_in_item (p_s_search_path) = ih_item_len(p_le_ih) / UNFM_P_SIZE;
+    else
+        pos_in_item (p_s_search_path) = ih_item_len( p_le_ih );
+  
+    return POSITION_NOT_FOUND;
+}
+
+
+/* Compare given item and item pointed to by the path. */
+int comp_items (const struct item_head * stored_ih, const struct path * p_s_path)
+{
+    struct buffer_head  * p_s_bh;
+    struct item_head    * ih;
+
+    /* Last buffer at the path is not in the tree. */
+    if ( ! B_IS_IN_TREE(p_s_bh = PATH_PLAST_BUFFER(p_s_path)) )
+	return 1;
+
+    /* Last path position is invalid. */
+    if ( PATH_LAST_POSITION(p_s_path) >= B_NR_ITEMS(p_s_bh) )
+	return 1;
+
+    /* we need only to know, whether it is the same item */
+    ih = get_ih (p_s_path);
+    return memcmp (stored_ih, ih, IH_SIZE);
+}
+
+
+/* unformatted nodes are not logged anymore, ever.  This is safe
+** now
+*/
+#define held_by_others(bh) (atomic_read(&(bh)->b_count) > 1)
+
+// block can not be forgotten as it is in I/O or held by someone
+#define block_in_use(bh) (buffer_locked(bh) || (held_by_others(bh)))
+
+
+
+// prepare for delete or cut of direct item
+static inline int prepare_for_direct_item (struct path * path,
+					   struct item_head * le_ih,
+					   struct inode * inode,
+					   loff_t new_file_length,
+					   int * cut_size)
+{
+    loff_t round_len;
+
+
+    if ( new_file_length == max_reiserfs_offset (inode) ) {
+	/* item has to be deleted */
+	*cut_size = -(IH_SIZE + ih_item_len(le_ih));
+	return M_DELETE;
+    }
+	
+    // new file gets truncated
+    if (get_inode_item_key_version (inode) == KEY_FORMAT_3_6) {
+	// 
+	round_len = ROUND_UP (new_file_length); 
+	/* this was n_new_file_length < le_ih ... */
+	if ( round_len < le_ih_k_offset (le_ih) )  {
+	    *cut_size = -(IH_SIZE + ih_item_len(le_ih));
+	    return M_DELETE; /* Delete this item. */
+	}
+	/* Calculate first position and size for cutting from item. */
+	pos_in_item (path) = round_len - (le_ih_k_offset (le_ih) - 1);
+	*cut_size = -(ih_item_len(le_ih) - pos_in_item(path));
+	
+	return M_CUT; /* Cut from this item. */
+    }
+
+
+    // old file: items may have any length
+
+    if ( new_file_length < le_ih_k_offset (le_ih) )  {
+	*cut_size = -(IH_SIZE + ih_item_len(le_ih));
+	return M_DELETE; /* Delete this item. */
+    }
+    /* Calculate first position and size for cutting from item. */
+    *cut_size = -(ih_item_len(le_ih) -
+		      (pos_in_item (path) = new_file_length + 1 - le_ih_k_offset (le_ih)));
+    return M_CUT; /* Cut from this item. */
+}
+
+
+static inline int prepare_for_direntry_item (struct path * path,
+					     struct item_head * le_ih,
+					     struct inode * inode,
+					     loff_t new_file_length,
+					     int * cut_size)
+{
+    if (le_ih_k_offset (le_ih) == DOT_OFFSET && 
+	new_file_length == max_reiserfs_offset (inode)) {
+	RFALSE( ih_entry_count (le_ih) != 2,
+	        "PAP-5220: incorrect empty directory item (%h)", le_ih);
+	*cut_size = -(IH_SIZE + ih_item_len(le_ih));
+	return M_DELETE; /* Delete the directory item containing "." and ".." entry. */
+    }
+    
+    if ( ih_entry_count (le_ih) == 1 )  {
+	/* Delete the directory item such as there is one record only
+	   in this item*/
+	*cut_size = -(IH_SIZE + ih_item_len(le_ih));
+	return M_DELETE;
+    }
+    
+    /* Cut one record from the directory item. */
+    *cut_size = -(DEH_SIZE + entry_length (get_last_bh (path), le_ih, pos_in_item (path)));
+    return M_CUT; 
+}
+
+
+/*  If the path points to a directory or direct item, calculate mode and the size cut, for balance.
+    If the path points to an indirect item, remove some number of its unformatted nodes.
+    In case of file truncate calculate whether this item must be deleted/truncated or last
+    unformatted node of this item will be converted to a direct item.
+    This function returns a determination of what balance mode the calling function should employ. */
+static char  prepare_for_delete_or_cut(
+				       struct reiserfs_transaction_handle *th, 
+				       struct inode * inode,
+				       struct path         * p_s_path,
+				       const struct cpu_key      * p_s_item_key,
+				       int                 * p_n_removed,      /* Number of unformatted nodes which were removed
+										  from end of the file. */
+				       int                 * p_n_cut_size,
+				       unsigned long long    n_new_file_length /* MAX_KEY_OFFSET in case of delete. */
+    ) {
+    struct super_block  * p_s_sb = inode->i_sb;
+    struct item_head    * p_le_ih = PATH_PITEM_HEAD(p_s_path);
+    struct buffer_head  * p_s_bh = PATH_PLAST_BUFFER(p_s_path);
+
+    BUG_ON (!th->t_trans_id);
+
+    /* Stat_data item. */
+    if ( is_statdata_le_ih (p_le_ih) ) {
+
+	RFALSE( n_new_file_length != max_reiserfs_offset (inode),
+		"PAP-5210: mode must be M_DELETE");
+
+	*p_n_cut_size = -(IH_SIZE + ih_item_len(p_le_ih));
+	return M_DELETE;
+    }
+
+
+    /* Directory item. */
+    if ( is_direntry_le_ih (p_le_ih) )
+	return prepare_for_direntry_item (p_s_path, p_le_ih, inode, n_new_file_length, p_n_cut_size);
+
+    /* Direct item. */
+    if ( is_direct_le_ih (p_le_ih) )
+	return prepare_for_direct_item (p_s_path, p_le_ih, inode, n_new_file_length, p_n_cut_size);
+
+
+    /* Case of an indirect item. */
+    {
+	int                   n_unfm_number,    /* Number of the item unformatted nodes. */
+	    n_counter,
+	    n_blk_size;
+	__u32               * p_n_unfm_pointer; /* Pointer to the unformatted node number. */