hfsplus: fix longname handling

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>