fs/ntfs3: Added comments to frecord functions

Added some comments in frecord.c for more context.
Also changed run_lookup to static because it's an internal function.
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>

fs/ntfs3/bitmap.c

@@ -1393,9 +1393,8 @@ int wnd_extend(struct wnd_bitmap *wnd, size_t new_bits)
 
 void wnd_zone_set(struct wnd_bitmap *wnd, size_t lcn, size_t len)
 {
-	size_t zlen;
+	size_t zlen = wnd->zone_end - wnd->zone_bit;
 
-	zlen = wnd->zone_end - wnd->zone_bit;
 	if (zlen)
 		wnd_add_free_ext(wnd, wnd->zone_bit, zlen, false);
 

fs/ntfs3/frecord.c

@@ -1287,7 +1287,7 @@ static int ni_expand_mft_list(struct ntfs_inode *ni)
 	done = asize - run_size - SIZEOF_NONRESIDENT;
 	le32_sub_cpu(&ni->mi.mrec->used, done);
 
-	/* Estimate the size of second part: run_buf=NULL. */
+	/* Estimate packed size (run_buf=NULL). */
 	err = run_pack(run, svcn, evcn + 1 - svcn, NULL, sbi->record_size,
 		       &plen);
 	if (err < 0)
@@ -1317,6 +1317,7 @@ static int ni_expand_mft_list(struct ntfs_inode *ni)
 	attr->name_off = SIZEOF_NONRESIDENT_LE;
 	attr->flags = 0;
 
+	/* This function can't fail - cause already checked above. */
 	run_pack(run, svcn, evcn + 1 - svcn, Add2Ptr(attr, SIZEOF_NONRESIDENT),
 		 run_size, &plen);
 
@@ -1392,8 +1393,6 @@ int ni_expand_list(struct ntfs_inode *ni)
 
 	/* Split MFT data as much as possible. */
 	err = ni_expand_mft_list(ni);
-	if (err)
-		goto out;
 
 out:
 	return !err && !done ? -EOPNOTSUPP : err;
@@ -1419,6 +1418,7 @@ int ni_insert_nonresident(struct ntfs_inode *ni, enum ATTR_TYPE type,
 	u32 run_size, asize;
 	struct ntfs_sb_info *sbi = ni->mi.sbi;
 
+	/* Estimate packed size (run_buf=NULL). */
 	err = run_pack(run, svcn, len, NULL, sbi->max_bytes_per_attr - run_off,
 		       &plen);
 	if (err < 0)
@@ -1448,12 +1448,12 @@ int ni_insert_nonresident(struct ntfs_inode *ni, enum ATTR_TYPE type,
 	attr->name_off = cpu_to_le16(name_off);
 	attr->flags = flags;
 
+	/* This function can't fail - cause already checked above. */
 	run_pack(run, svcn, len, Add2Ptr(attr, run_off), run_size, &plen);
 
 	attr->nres.svcn = cpu_to_le64(svcn);
 	attr->nres.evcn = cpu_to_le64((u64)svcn + len - 1);
 
-	err = 0;
 	if (new_attr)
 		*new_attr = attr;
 

fs/ntfs3/ntfs_fs.h

@@ -773,7 +773,6 @@ bool run_lookup_entry(const struct runs_tree *run, CLST vcn, CLST *lcn,
 void run_truncate(struct runs_tree *run, CLST vcn);
 void run_truncate_head(struct runs_tree *run, CLST vcn);
 void run_truncate_around(struct runs_tree *run, CLST vcn);
-bool run_lookup(const struct runs_tree *run, CLST vcn, size_t *index);
 bool run_add_entry(struct runs_tree *run, CLST vcn, CLST lcn, CLST len,
 		   bool is_mft);
 bool run_collapse_range(struct runs_tree *run, CLST vcn, CLST len);

fs/ntfs3/run.c

@@ -31,7 +31,7 @@ struct ntfs_run {
  * Case of entry missing from list 'index' will be set to
  * point to insertion position for the entry question.
  */
-bool run_lookup(const struct runs_tree *run, CLST vcn, size_t *index)
+static bool run_lookup(const struct runs_tree *run, CLST vcn, size_t *index)
 {
 	size_t min_idx, max_idx, mid_idx;
 	struct ntfs_run *r;