With this patch, the intent to write to some block in the array can be logged
to a bitmap file. Each bit represents some number of sectors and is set
before any update happens, and only cleared when all writes relating to all
sectors are complete.
After an unclean shutdown, information in this bitmap can be used to optimise
resync - only sectors which could be out-of-sync need to be updated.
Also if a drive is removed and then added back into an array, the recovery can
make use of the bitmap to optimise reconstruction. This is not implemented in
this patch.
Currently the bitmap is stored in a file which must (obviously) be stored on a
separate device.
The patch only provided infrastructure. It does not update any personalities
to bitmap intent logging.
Md arrays can still be used with no bitmap file. This patch has minimal
impact on such arrays.
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
1/ change the return value (which is number-of-sectors synced)
from 'int' to 'sector_t'.
The number of sectors is usually easily small enough to fit
in an int, but if resync needs to abort, it may want to return
the total number of remaining sectors, which could be large.
Also errors cannot be returned as negative numbers now, so use
0 instead
2/ Add a 'skipped' return parameter to allow the array to report
that it skipped the sectors. This allows md to take this into account
in the speed calculations.
Currently there is no important skipping, but the bitmap-based-resync
that is coming will use this.
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus 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: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus 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: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This patch makes some needlessly global identifiers static.
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Acked-by: Arjan van de Ven <arjanv@infradead.org>
Acked-by: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus 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: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus 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: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
..as sync_page_io can be called on the write-out path.
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus 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!
