Always allow truncations to zero, even if budgeting thinks there
is no space. UBIFS reserves some space for deletions anyway.

Otherwise, the following happans:
1. create a file, and write as much as possible there, until ENOSPC
2. truncate the file, which fails with ENOSPC, which is not good.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Commit d70b67c8 fixed VFS and
it never calls FS lookup function in deleted directories now.
We may remove corresponding UBIFS check.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

UBIFS does not presently re-use inode numbers, so leaving
i_generation zero is most appropriate for now.
Signed-off-by: NAdrian Hunter <ext-adrian.hunter@nokia.com>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

UBIFS aligns node lengths to 8, so budgeting has to do the
same. Well, direntry, inode, and page budgets are already
aligned, but not inode data budget (e.g., data in special
devices or symlinks). Do this for inode data as well.
Also, add corresponding debugging checks.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

The 'ubifs_release_dirty_inode_budget()' was buggy and incorrectly
freed the budget, which led to not freeing all dirty data budget.
This patch fixes that.

Also, this patch fixes ubifs_mkdir() which passed 1 in dirty_ino_d,
which makes no sense. Well, it is harmless though.

Also, add few more useful assertions. And improve few debugging
messages.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

This is a new flash file system. See
http://www.linux-mtd.infradead.org/doc/ubifs.htmlSigned-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: NAdrian Hunter <ext-adrian.hunter@nokia.com>