[PATCH 00/12] quota: Redesign IO error handling interface V2

[Dmitry Monakhov <dmonakhov@openvz.org>]

This patchset is tended to provide interface for handling IO errors
from internal quota code.
Any error must being returned to fs-caller to signal about possible
quota inconsistency. I've done it in following way:

1) Handle low-level io errors from dqget() and it's callers
2) Handle errors from dquot_initialize
   This path catch most of IO error, but no all.
3) Check what i_dquot was initialized in each low-level function.
   There are two types of such functions
   3A) Charging functions (alloc_{space,inode}): Caller of such
       function may easy handle an error and abort an operation.
   3B) nofail functions (claim_space,free_{space,inode})
       In most cases caller can not abort an operation even if
       inode's quotas was semi-initialized, so I just skip this
       functions for now.

Notes: Ext{3,4} orphan_list_cleanup patch may be folded to corresponding
 dquot_initialize() patch, but IMHO this makes review more complicate.

Changes from V2
 - First patch (unify quota init condition in setattr) was accepted.
 - Fix according to Jan's comments. Except error handling in charge methods
 - Add missed error handling in add_dquot_ref
 - Split fs-speciffic callers of dquot_initialize() in to per-fs parts.
   This makes number of patches dangerously big, but this is the only
   way to make things right(Thank Jan for an suggestion).

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>