tree ea9f5c2d54e7e5397318ba9b91b0b88a33f179ae
parent 455c6fdbd219161bd09b1165f11699d6d73de11c
author NeilBrown <neilb@suse.de> 1397010340 +1000
committer NeilBrown <neilb@suse.de> 1397010419 +1000

md/bitmap: don't abuse i_writecount for bitmap files.

md bitmap code currently tries to use i_writecount to stop any other
process from writing to out bitmap file.  But that is really an abuse
and has bit-rotted so locking is all wrong.

So discard that - root should be allowed to shoot self in foot.

Still use it in a much less intrusive way to stop the same file being
used as bitmap on two different array, and apply other checks to
ensure the file is at least vaguely usable for bitmap storage
(is regular, is open for write.  Support for ->bmap is already checked
elsewhere).

Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: NeilBrown <neilb@suse.de>