hfsplus: fix longname handling

Longname is not correctly handled by hfsplus driver.  If an attempt to
create a longname(>255) file/directory is made, it succeeds by creating a
file/directory with HFSPLUS_MAX_STRLEN and incorrect catalog key.  Thus
leaving the volume in an inconsistent state.  This patch fixes this issue.

Although lookup is always called first to create a negative entry, so just
doing a check in lookup would probably fix this issue.  I choose to
propagate error to other iops as well.

Please NOTE: I have factored out hfsplus_cat_build_key_with_cnid from
hfsplus_cat_build_key, to avoid unncessary branching.

Thanks a lot.

  TEST:
  ------
  dir="TEST_DIR"
  cdir=`pwd`
  name255="_123456789_123456789_123456789_123456789_123456789_123456789\
  _123456789_123456789_123456789_123456789_123456789_123456789_123456789\
  _123456789_123456789_123456789_123456789_123456789_123456789_123456789\
  _123456789_123456789_123456789_123456789_123456789_1234"
  name256="${name255}5"

  mkdir $dir
  cd $dir
  touch $name255
  rm -f $name255
  touch $name256
  ls -la
  cd $cdir
  rm -rf $dir

  RESULT:
  -------
  [sougata@ultrabook tmp]$ cdir=`pwd`
  [sougata@ultrabook tmp]$
  name255="_123456789_123456789_123456789_123456789_123456789_123456789\
   > _123456789_123456789_123456789_123456789_123456789_123456789_123456789\
   > _123456789_123456789_123456789_123456789_123456789_123456789_123456789\
   > _123456789_123456789_123456789_123456789_123456789_1234"
  [sougata@ultrabook tmp]$ name256="${name255}5"
  [sougata@ultrabook tmp]$
  [sougata@ultrabook tmp]$ mkdir $dir
  [sougata@ultrabook tmp]$ cd $dir
  [sougata@ultrabook TEST_DIR]$ touch $name255
  [sougata@ultrabook TEST_DIR]$ rm -f $name255
  [sougata@ultrabook TEST_DIR]$ touch $name256
  [sougata@ultrabook TEST_DIR]$ ls -la
  ls: cannot access
  _123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_1234:
  No such file or directory
  total 0
  drwxrwxr-x 1 sougata sougata 3 Feb 20 19:56 .
  drwxrwxrwx 1 root    root    6 Feb 20 19:56 ..
  -????????? ? ?       ?       ?            ?
  _123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789_1234
  [sougata@ultrabook TEST_DIR]$ cd $cdir
  [sougata@ultrabook tmp]$ rm -rf $dir
  rm: cannot remove `TEST_DIR': Directory not empty

-ENAMETOOLONG returned from hfsplus_asc2uni was not propaged to iops.
This allowed hfsplus to create files/directories with HFSPLUS_MAX_STRLEN
and incorrect keys, leaving the FS in an inconsistent state.  This patch
fixes this issue.

Signed-off-by: Sougata Santra <sougata@tuxera.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Vyacheslav Dubeyko <slava@dubeyko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>