2011-07-26 (화), 12:26 +1000, NeilBrown: > On Sat, 23 Jul 2011 00:03:45 +0900 Namhyung Kim <namhyung@xxxxxxxxx> wrote: > > > NeilBrown <neilb@xxxxxxx> writes: > > > > > This the first step in allowing md to track bad-blocks per-device so > > > that we can fail individual blocks rather than the whole device. > > > > > > This patch just adds a data structure for recording bad blocks, with > > > routines to add, remove, search the list. > > > > > > Signed-off-by: NeilBrown <neilb@xxxxxxx> > > > --- > > > > > > drivers/md/md.c | 457 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ > > > drivers/md/md.h | 49 ++++++ > > > 2 files changed, 502 insertions(+), 4 deletions(-) > > > > > > + > > > +/* Bad block management. > > > + * We can record which blocks on each device are 'bad' and so just > > > + * fail those blocks, or that stripe, rather than the whole device. > > > + * Entries in the bad-block table are 64bits wide. This comprises: > > > + * Length of bad-range, in sectors: 0-511 for lengths 1-512 > > > + * Start of bad-range, sector offset, 54 bits (allows 8 exbibytes) > > > + * A 'shift' can be set so that larger blocks are tracked and > > > + * consequently larger devices can be covered. > > > + * 'Acknowledged' flag - 1 bit. - the most significant bit. > > > + */ > > > +/* Locking of the bad-block table is a two-layer affair. > > > + * Read access through ->active_page only requires an rcu_readlock. > > > + * However if ->active_page is found to be NULL, the table > > > + * should be accessed through ->page which requires an irq-spinlock. > > > + * Updating the page requires setting ->active_page to NULL, > > > + * synchronising with rcu, then updating ->page under the same > > > + * irq-spinlock. > > > + * We always set or clear bad blocks from process context, but > > > + * might look-up bad blocks from interrupt/bh context. > > > + * > > > > Empty line. > > > > If the locking is complex, it'd be better defining separate functions to > > deal with it, IMHO. Please see below. > > I too have been feeling uncomfortable about the locking and I recently > realised that I really should be using a seqlock rather than trying to force > RCU into the mould. So I have changed it and it is much better now. Below > is new version. > > > > > +EXPORT_SYMBOL_GPL(rdev_set_badblocks); > > > > I think it would be better if all exported functions in md.c have > > prefixed 'md_'. > > > > Probably good advice. I don't think I'll change it now but maybe in a > subsequent patch so that I change them all at once. > > Thanks, > NeilBrown > > commit 0980048be17a45ae9e181ad04a549c31a499dee9 > Author: NeilBrown <neilb@xxxxxxx> > Date: Tue Jul 26 12:22:08 2011 +1000 > > md: beginnings of bad block management. > > This the first step in allowing md to track bad-blocks per-device so > that we can fail individual blocks rather than the whole device. > > This patch just adds a data structure for recording bad blocks, with > routines to add, remove, search the list. > > Signed-off-by: NeilBrown <neilb@xxxxxxx> with your another badblocks.page fix: Reviewed-by: Namhyung Kim <namhyung@xxxxxxxxx> -- Regards, Namhyung Kim -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
