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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@suse.de> Reviewed-by: Namhyung Kim <namhyung@gmail.com>
This commit is contained in:
NeilBrown
parent
a519b26dbe
commit
2230dfe4cc
415
drivers/md/md.c
415
drivers/md/md.c
@ -1952,6 +1952,9 @@ static void unbind_rdev_from_array(mdk_rdev_t * rdev)
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sysfs_remove_link(&rdev->kobj, "block");
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sysfs_put(rdev->sysfs_state);
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rdev->sysfs_state = NULL;
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kfree(rdev->badblocks.page);
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rdev->badblocks.count = 0;
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rdev->badblocks.page = NULL;
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/* We need to delay this, otherwise we can deadlock when
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* writing to 'remove' to "dev/state". We also need
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* to delay it due to rcu usage.
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@ -2778,7 +2781,7 @@ static struct kobj_type rdev_ktype = {
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.default_attrs = rdev_default_attrs,
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};
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void md_rdev_init(mdk_rdev_t *rdev)
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int md_rdev_init(mdk_rdev_t *rdev)
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{
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rdev->desc_nr = -1;
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rdev->saved_raid_disk = -1;
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@ -2794,6 +2797,19 @@ void md_rdev_init(mdk_rdev_t *rdev)
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INIT_LIST_HEAD(&rdev->same_set);
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init_waitqueue_head(&rdev->blocked_wait);
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/* Add space to store bad block list.
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* This reserves the space even on arrays where it cannot
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* be used - I wonder if that matters
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*/
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rdev->badblocks.count = 0;
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rdev->badblocks.shift = 0;
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rdev->badblocks.page = kmalloc(PAGE_SIZE, GFP_KERNEL);
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seqlock_init(&rdev->badblocks.lock);
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if (rdev->badblocks.page == NULL)
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return -ENOMEM;
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return 0;
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}
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EXPORT_SYMBOL_GPL(md_rdev_init);
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/*
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@ -2819,8 +2835,11 @@ static mdk_rdev_t *md_import_device(dev_t newdev, int super_format, int super_mi
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return ERR_PTR(-ENOMEM);
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}
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md_rdev_init(rdev);
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if ((err = alloc_disk_sb(rdev)))
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err = md_rdev_init(rdev);
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if (err)
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goto abort_free;
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err = alloc_disk_sb(rdev);
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if (err)
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goto abort_free;
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err = lock_rdev(rdev, newdev, super_format == -2);
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@ -2865,6 +2884,7 @@ abort_free:
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unlock_rdev(rdev);
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free_disk_sb(rdev);
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}
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kfree(rdev->badblocks.page);
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kfree(rdev);
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return ERR_PTR(err);
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}
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@ -7327,6 +7347,395 @@ void md_wait_for_blocked_rdev(mdk_rdev_t *rdev, mddev_t *mddev)
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}
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EXPORT_SYMBOL(md_wait_for_blocked_rdev);
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/* Bad block management.
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* We can record which blocks on each device are 'bad' and so just
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* fail those blocks, or that stripe, rather than the whole device.
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* Entries in the bad-block table are 64bits wide. This comprises:
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* Length of bad-range, in sectors: 0-511 for lengths 1-512
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* Start of bad-range, sector offset, 54 bits (allows 8 exbibytes)
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* A 'shift' can be set so that larger blocks are tracked and
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* consequently larger devices can be covered.
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* 'Acknowledged' flag - 1 bit. - the most significant bit.
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*
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* Locking of the bad-block table uses a seqlock so md_is_badblock
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* might need to retry if it is very unlucky.
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* We will sometimes want to check for bad blocks in a bi_end_io function,
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* so we use the write_seqlock_irq variant.
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*
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* When looking for a bad block we specify a range and want to
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* know if any block in the range is bad. So we binary-search
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* to the last range that starts at-or-before the given endpoint,
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* (or "before the sector after the target range")
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* then see if it ends after the given start.
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* We return
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* 0 if there are no known bad blocks in the range
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* 1 if there are known bad block which are all acknowledged
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* -1 if there are bad blocks which have not yet been acknowledged in metadata.
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* plus the start/length of the first bad section we overlap.
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*/
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int md_is_badblock(struct badblocks *bb, sector_t s, int sectors,
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sector_t *first_bad, int *bad_sectors)
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{
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int hi;
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int lo = 0;
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u64 *p = bb->page;
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int rv = 0;
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sector_t target = s + sectors;
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unsigned seq;
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if (bb->shift > 0) {
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/* round the start down, and the end up */
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s >>= bb->shift;
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target += (1<<bb->shift) - 1;
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target >>= bb->shift;
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sectors = target - s;
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}
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/* 'target' is now the first block after the bad range */
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retry:
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seq = read_seqbegin(&bb->lock);
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hi = bb->count;
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/* Binary search between lo and hi for 'target'
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* i.e. for the last range that starts before 'target'
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*/
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/* INVARIANT: ranges before 'lo' and at-or-after 'hi'
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* are known not to be the last range before target.
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* VARIANT: hi-lo is the number of possible
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* ranges, and decreases until it reaches 1
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*/
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while (hi - lo > 1) {
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int mid = (lo + hi) / 2;
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sector_t a = BB_OFFSET(p[mid]);
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if (a < target)
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/* This could still be the one, earlier ranges
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* could not. */
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lo = mid;
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else
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/* This and later ranges are definitely out. */
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hi = mid;
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}
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/* 'lo' might be the last that started before target, but 'hi' isn't */
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if (hi > lo) {
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/* need to check all range that end after 's' to see if
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* any are unacknowledged.
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*/
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while (lo >= 0 &&
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BB_OFFSET(p[lo]) + BB_LEN(p[lo]) > s) {
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if (BB_OFFSET(p[lo]) < target) {
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/* starts before the end, and finishes after
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* the start, so they must overlap
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*/
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if (rv != -1 && BB_ACK(p[lo]))
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rv = 1;
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else
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rv = -1;
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*first_bad = BB_OFFSET(p[lo]);
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*bad_sectors = BB_LEN(p[lo]);
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}
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lo--;
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}
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}
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if (read_seqretry(&bb->lock, seq))
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goto retry;
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return rv;
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}
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EXPORT_SYMBOL_GPL(md_is_badblock);
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/*
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* Add a range of bad blocks to the table.
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* This might extend the table, or might contract it
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* if two adjacent ranges can be merged.
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* We binary-search to find the 'insertion' point, then
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* decide how best to handle it.
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*/
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static int md_set_badblocks(struct badblocks *bb, sector_t s, int sectors,
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int acknowledged)
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{
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u64 *p;
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int lo, hi;
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int rv = 1;
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if (bb->shift < 0)
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/* badblocks are disabled */
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return 0;
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if (bb->shift) {
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/* round the start down, and the end up */
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sector_t next = s + sectors;
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s >>= bb->shift;
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next += (1<<bb->shift) - 1;
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next >>= bb->shift;
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sectors = next - s;
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}
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write_seqlock_irq(&bb->lock);
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p = bb->page;
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lo = 0;
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hi = bb->count;
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/* Find the last range that starts at-or-before 's' */
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while (hi - lo > 1) {
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int mid = (lo + hi) / 2;
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sector_t a = BB_OFFSET(p[mid]);
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if (a <= s)
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lo = mid;
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else
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hi = mid;
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}
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if (hi > lo && BB_OFFSET(p[lo]) > s)
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hi = lo;
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if (hi > lo) {
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/* we found a range that might merge with the start
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* of our new range
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*/
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sector_t a = BB_OFFSET(p[lo]);
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sector_t e = a + BB_LEN(p[lo]);
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int ack = BB_ACK(p[lo]);
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if (e >= s) {
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/* Yes, we can merge with a previous range */
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if (s == a && s + sectors >= e)
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/* new range covers old */
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ack = acknowledged;
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else
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ack = ack && acknowledged;
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if (e < s + sectors)
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e = s + sectors;
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if (e - a <= BB_MAX_LEN) {
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p[lo] = BB_MAKE(a, e-a, ack);
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s = e;
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} else {
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/* does not all fit in one range,
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* make p[lo] maximal
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*/
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if (BB_LEN(p[lo]) != BB_MAX_LEN)
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p[lo] = BB_MAKE(a, BB_MAX_LEN, ack);
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s = a + BB_MAX_LEN;
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}
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sectors = e - s;
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}
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}
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if (sectors && hi < bb->count) {
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/* 'hi' points to the first range that starts after 's'.
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* Maybe we can merge with the start of that range */
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sector_t a = BB_OFFSET(p[hi]);
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sector_t e = a + BB_LEN(p[hi]);
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int ack = BB_ACK(p[hi]);
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if (a <= s + sectors) {
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/* merging is possible */
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if (e <= s + sectors) {
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/* full overlap */
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e = s + sectors;
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ack = acknowledged;
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} else
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ack = ack && acknowledged;
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a = s;
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if (e - a <= BB_MAX_LEN) {
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p[hi] = BB_MAKE(a, e-a, ack);
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s = e;
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} else {
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p[hi] = BB_MAKE(a, BB_MAX_LEN, ack);
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s = a + BB_MAX_LEN;
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}
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sectors = e - s;
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lo = hi;
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hi++;
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}
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}
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if (sectors == 0 && hi < bb->count) {
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/* we might be able to combine lo and hi */
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/* Note: 's' is at the end of 'lo' */
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sector_t a = BB_OFFSET(p[hi]);
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int lolen = BB_LEN(p[lo]);
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int hilen = BB_LEN(p[hi]);
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int newlen = lolen + hilen - (s - a);
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if (s >= a && newlen < BB_MAX_LEN) {
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/* yes, we can combine them */
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int ack = BB_ACK(p[lo]) && BB_ACK(p[hi]);
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p[lo] = BB_MAKE(BB_OFFSET(p[lo]), newlen, ack);
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memmove(p + hi, p + hi + 1,
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(bb->count - hi - 1) * 8);
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bb->count--;
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}
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}
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while (sectors) {
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/* didn't merge (it all).
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* Need to add a range just before 'hi' */
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if (bb->count >= MD_MAX_BADBLOCKS) {
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/* No room for more */
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rv = 0;
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break;
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} else {
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int this_sectors = sectors;
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memmove(p + hi + 1, p + hi,
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(bb->count - hi) * 8);
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bb->count++;
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if (this_sectors > BB_MAX_LEN)
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this_sectors = BB_MAX_LEN;
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p[hi] = BB_MAKE(s, this_sectors, acknowledged);
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sectors -= this_sectors;
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s += this_sectors;
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}
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}
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bb->changed = 1;
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write_sequnlock_irq(&bb->lock);
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return rv;
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}
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int rdev_set_badblocks(mdk_rdev_t *rdev, sector_t s, int sectors,
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int acknowledged)
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{
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int rv = md_set_badblocks(&rdev->badblocks,
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s + rdev->data_offset, sectors, acknowledged);
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if (rv) {
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/* Make sure they get written out promptly */
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set_bit(MD_CHANGE_CLEAN, &rdev->mddev->flags);
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md_wakeup_thread(rdev->mddev->thread);
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}
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return rv;
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}
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EXPORT_SYMBOL_GPL(rdev_set_badblocks);
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/*
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* Remove a range of bad blocks from the table.
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* This may involve extending the table if we spilt a region,
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* but it must not fail. So if the table becomes full, we just
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* drop the remove request.
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*/
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static int md_clear_badblocks(struct badblocks *bb, sector_t s, int sectors)
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{
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u64 *p;
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int lo, hi;
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sector_t target = s + sectors;
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int rv = 0;
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if (bb->shift > 0) {
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/* When clearing we round the start up and the end down.
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* This should not matter as the shift should align with
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* the block size and no rounding should ever be needed.
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* However it is better the think a block is bad when it
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* isn't than to think a block is not bad when it is.
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*/
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s += (1<<bb->shift) - 1;
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s >>= bb->shift;
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target >>= bb->shift;
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sectors = target - s;
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}
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write_seqlock_irq(&bb->lock);
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p = bb->page;
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lo = 0;
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hi = bb->count;
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/* Find the last range that starts before 'target' */
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while (hi - lo > 1) {
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int mid = (lo + hi) / 2;
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sector_t a = BB_OFFSET(p[mid]);
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if (a < target)
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lo = mid;
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else
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hi = mid;
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}
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if (hi > lo) {
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/* p[lo] is the last range that could overlap the
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* current range. Earlier ranges could also overlap,
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* but only this one can overlap the end of the range.
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*/
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if (BB_OFFSET(p[lo]) + BB_LEN(p[lo]) > target) {
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/* Partial overlap, leave the tail of this range */
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int ack = BB_ACK(p[lo]);
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sector_t a = BB_OFFSET(p[lo]);
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sector_t end = a + BB_LEN(p[lo]);
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if (a < s) {
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/* we need to split this range */
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if (bb->count >= MD_MAX_BADBLOCKS) {
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rv = 0;
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goto out;
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}
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memmove(p+lo+1, p+lo, (bb->count - lo) * 8);
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bb->count++;
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p[lo] = BB_MAKE(a, s-a, ack);
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lo++;
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}
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p[lo] = BB_MAKE(target, end - target, ack);
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/* there is no longer an overlap */
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hi = lo;
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lo--;
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}
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while (lo >= 0 &&
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BB_OFFSET(p[lo]) + BB_LEN(p[lo]) > s) {
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/* This range does overlap */
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if (BB_OFFSET(p[lo]) < s) {
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/* Keep the early parts of this range. */
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int ack = BB_ACK(p[lo]);
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sector_t start = BB_OFFSET(p[lo]);
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p[lo] = BB_MAKE(start, s - start, ack);
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/* now low doesn't overlap, so.. */
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break;
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}
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lo--;
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}
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/* 'lo' is strictly before, 'hi' is strictly after,
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* anything between needs to be discarded
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*/
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if (hi - lo > 1) {
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memmove(p+lo+1, p+hi, (bb->count - hi) * 8);
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bb->count -= (hi - lo - 1);
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}
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}
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bb->changed = 1;
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out:
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write_sequnlock_irq(&bb->lock);
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return rv;
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}
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int rdev_clear_badblocks(mdk_rdev_t *rdev, sector_t s, int sectors)
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{
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return md_clear_badblocks(&rdev->badblocks,
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s + rdev->data_offset,
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sectors);
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}
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EXPORT_SYMBOL_GPL(rdev_clear_badblocks);
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/*
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* Acknowledge all bad blocks in a list.
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* This only succeeds if ->changed is clear. It is used by
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* in-kernel metadata updates
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*/
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void md_ack_all_badblocks(struct badblocks *bb)
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{
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if (bb->page == NULL || bb->changed)
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/* no point even trying */
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return;
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write_seqlock_irq(&bb->lock);
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if (bb->changed == 0) {
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u64 *p = bb->page;
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int i;
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for (i = 0; i < bb->count ; i++) {
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if (!BB_ACK(p[i])) {
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sector_t start = BB_OFFSET(p[i]);
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int len = BB_LEN(p[i]);
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p[i] = BB_MAKE(start, len, 1);
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}
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}
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}
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write_sequnlock_irq(&bb->lock);
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}
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EXPORT_SYMBOL_GPL(md_ack_all_badblocks);
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static int md_notify_reboot(struct notifier_block *this,
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unsigned long code, void *x)
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{
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@ -29,6 +29,13 @@
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typedef struct mddev_s mddev_t;
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typedef struct mdk_rdev_s mdk_rdev_t;
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/* Bad block numbers are stored sorted in a single page.
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* 64bits is used for each block or extent.
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* 54 bits are sector number, 9 bits are extent size,
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* 1 bit is an 'acknowledged' flag.
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*/
|
||||
#define MD_MAX_BADBLOCKS (PAGE_SIZE/8)
|
||||
|
||||
/*
|
||||
* MD's 'extended' device
|
||||
*/
|
||||
@ -111,8 +118,47 @@ struct mdk_rdev_s
|
||||
|
||||
struct sysfs_dirent *sysfs_state; /* handle for 'state'
|
||||
* sysfs entry */
|
||||
|
||||
struct badblocks {
|
||||
int count; /* count of bad blocks */
|
||||
int shift; /* shift from sectors to block size
|
||||
* a -ve shift means badblocks are
|
||||
* disabled.*/
|
||||
u64 *page; /* badblock list */
|
||||
int changed;
|
||||
seqlock_t lock;
|
||||
} badblocks;
|
||||
};
|
||||
|
||||
#define BB_LEN_MASK (0x00000000000001FFULL)
|
||||
#define BB_OFFSET_MASK (0x7FFFFFFFFFFFFE00ULL)
|
||||
#define BB_ACK_MASK (0x8000000000000000ULL)
|
||||
#define BB_MAX_LEN 512
|
||||
#define BB_OFFSET(x) (((x) & BB_OFFSET_MASK) >> 9)
|
||||
#define BB_LEN(x) (((x) & BB_LEN_MASK) + 1)
|
||||
#define BB_ACK(x) (!!((x) & BB_ACK_MASK))
|
||||
#define BB_MAKE(a, l, ack) (((a)<<9) | ((l)-1) | ((u64)(!!(ack)) << 63))
|
||||
|
||||
extern int md_is_badblock(struct badblocks *bb, sector_t s, int sectors,
|
||||
sector_t *first_bad, int *bad_sectors);
|
||||
static inline int is_badblock(mdk_rdev_t *rdev, sector_t s, int sectors,
|
||||
sector_t *first_bad, int *bad_sectors)
|
||||
{
|
||||
if (unlikely(rdev->badblocks.count)) {
|
||||
int rv = md_is_badblock(&rdev->badblocks, rdev->data_offset + s,
|
||||
sectors,
|
||||
first_bad, bad_sectors);
|
||||
if (rv)
|
||||
*first_bad -= rdev->data_offset;
|
||||
return rv;
|
||||
}
|
||||
return 0;
|
||||
}
|
||||
extern int rdev_set_badblocks(mdk_rdev_t *rdev, sector_t s, int sectors,
|
||||
int acknowledged);
|
||||
extern int rdev_clear_badblocks(mdk_rdev_t *rdev, sector_t s, int sectors);
|
||||
extern void md_ack_all_badblocks(struct badblocks *bb);
|
||||
|
||||
struct mddev_s
|
||||
{
|
||||
void *private;
|
||||
@ -517,7 +563,7 @@ extern void mddev_init(mddev_t *mddev);
|
||||
extern int md_run(mddev_t *mddev);
|
||||
extern void md_stop(mddev_t *mddev);
|
||||
extern void md_stop_writes(mddev_t *mddev);
|
||||
extern void md_rdev_init(mdk_rdev_t *rdev);
|
||||
extern int md_rdev_init(mdk_rdev_t *rdev);
|
||||
|
||||
extern void mddev_suspend(mddev_t *mddev);
|
||||
extern void mddev_resume(mddev_t *mddev);
|
||||
|
||||
Loading…
Reference in New Issue
Block a user