When md marks the superblock dirty before a write, it calls
generic_make_request (to write the superblock) from within
generic_make_request (to write the first dirty block), which could cause
problems later.

With this patch, the superblock write is always done by the helper thread, and
write request are delayed until that write completes.

Also, the locking around marking the array dirty and writing the superblock is
improved to avoid possible races.
Signed-off-by: NNeil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

md_enter_safemode checks if it is time to mark the md superblock as 'clean'.
i.e.  if all writes have completed and a suitable delay has passed.

This is currently called from md_handle_safemode which in-turn is called
(almost) every time md_check_recovery is called, and from the end of
md_do_sync which causes the mddev->thread to run, which will always call
md_check_recovery as well.

So it doesn't need to be a separate function and fits quite well into
md_check_recovery.

The "almost" is because multipathd calls md_check_recovery but not
md_handle_safemode.  This is OK because the code from md_enter_safemode is a
no-op if mddev->safemode == 0, which it always is for a multipathd (providing
we don't allow it to be set to 2 on a signal...)
Signed-off-by: NNeil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Currently if add_new_disk is used to hot-add a drive to a degraded array,
recovery doesn't start ...  because we didn't tell it to.
Signed-off-by: NNeil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This patch makes some needlessly global identifiers static.
Signed-off-by: NAdrian Bunk <bunk@stusta.de>
Acked-by: NArjan van de Ven <arjanv@infradead.org>
Acked-by: NTrond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

The conditions that cause these calls to MD_BUG are not kernel bugs, just
oddities in what userspace is asking for.

Also convert analyze_sbs to return void, and the value it returned was
always 0.
Signed-off-by: NNeil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

There is a tiny race when de-registering an MD thread, in that the thread
could disappear before it is set a SIGKILL, causing send_sig to have
problems.  

This is most easily closed by holding tasklist_lock between enabling the
thread to exit (setting ->run to NULL) and telling it to exit.

(akpm: ick.  Needs to use kthread API and stop using signals)
Signed-off-by: NNeil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

..as sync_page_io can be called on the write-out path.
Signed-off-by: NNeil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!