md/raid1: avoid reading from known bad blocks.
Now that we have a bad block list, we should not read from those
blocks.
There are several main parts to this:
1/ read_balance needs to check for bad blocks, and return not only
the chosen device, but also how many good blocks are available
there.
2/ fix_read_error needs to avoid trying to read from bad blocks.
3/ read submission must be ready to issue multiple reads to
different devices as different bad blocks on different devices
could mean that a single large read cannot be served by any one
device, but can still be served by the array.
This requires keeping count of the number of outstanding requests
per bio. This count is stored in 'bi_phys_segments'
4/ retrying a read needs to also be ready to submit a smaller read
and queue another request for the rest.
This does not yet handle bad blocks when reading to perform resync,
recovery, or check.
'md_trim_bio' will also be used for RAID10, so put it in md.c and
export it.
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 8db311d..cc3939d 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -41,11 +41,7 @@
#include "bitmap.h"
#define DEBUG 0
-#if DEBUG
-#define PRINTK(x...) printk(x)
-#else
-#define PRINTK(x...)
-#endif
+#define PRINTK(x...) do { if (DEBUG) printk(x); } while (0)
/*
* Number of guaranteed r1bios in case of extreme VM load:
@@ -177,12 +173,6 @@
{
conf_t *conf = r1_bio->mddev->private;
- /*
- * Wake up any possible resync thread that waits for the device
- * to go idle.
- */
- allow_barrier(conf);
-
put_all_bios(conf, r1_bio);
mempool_free(r1_bio, conf->r1bio_pool);
}
@@ -223,6 +213,33 @@
* operation and are ready to return a success/failure code to the buffer
* cache layer.
*/
+static void call_bio_endio(r1bio_t *r1_bio)
+{
+ struct bio *bio = r1_bio->master_bio;
+ int done;
+ conf_t *conf = r1_bio->mddev->private;
+
+ if (bio->bi_phys_segments) {
+ unsigned long flags;
+ spin_lock_irqsave(&conf->device_lock, flags);
+ bio->bi_phys_segments--;
+ done = (bio->bi_phys_segments == 0);
+ spin_unlock_irqrestore(&conf->device_lock, flags);
+ } else
+ done = 1;
+
+ if (!test_bit(R1BIO_Uptodate, &r1_bio->state))
+ clear_bit(BIO_UPTODATE, &bio->bi_flags);
+ if (done) {
+ bio_endio(bio, 0);
+ /*
+ * Wake up any possible resync thread that waits for the device
+ * to go idle.
+ */
+ allow_barrier(conf);
+ }
+}
+
static void raid_end_bio_io(r1bio_t *r1_bio)
{
struct bio *bio = r1_bio->master_bio;
@@ -235,8 +252,7 @@
(unsigned long long) bio->bi_sector +
(bio->bi_size >> 9) - 1);
- bio_endio(bio,
- test_bit(R1BIO_Uptodate, &r1_bio->state) ? 0 : -EIO);
+ call_bio_endio(r1_bio);
}
free_r1bio(r1_bio);
}
@@ -295,6 +311,7 @@
bdevname(conf->mirrors[mirror].rdev->bdev,
b),
(unsigned long long)r1_bio->sector);
+ set_bit(R1BIO_ReadError, &r1_bio->state);
reschedule_retry(r1_bio);
}
@@ -381,7 +398,7 @@
(unsigned long long) mbio->bi_sector,
(unsigned long long) mbio->bi_sector +
(mbio->bi_size >> 9) - 1);
- bio_endio(mbio, 0);
+ call_bio_endio(r1_bio);
}
}
}
@@ -412,10 +429,11 @@
*
* The rdev for the device selected will have nr_pending incremented.
*/
-static int read_balance(conf_t *conf, r1bio_t *r1_bio)
+static int read_balance(conf_t *conf, r1bio_t *r1_bio, int *max_sectors)
{
const sector_t this_sector = r1_bio->sector;
- const int sectors = r1_bio->sectors;
+ int sectors;
+ int best_good_sectors;
int start_disk;
int best_disk;
int i;
@@ -430,8 +448,11 @@
* We take the first readable disk when above the resync window.
*/
retry:
+ sectors = r1_bio->sectors;
best_disk = -1;
best_dist = MaxSector;
+ best_good_sectors = 0;
+
if (conf->mddev->recovery_cp < MaxSector &&
(this_sector + sectors >= conf->next_resync)) {
choose_first = 1;
@@ -443,6 +464,9 @@
for (i = 0 ; i < conf->raid_disks ; i++) {
sector_t dist;
+ sector_t first_bad;
+ int bad_sectors;
+
int disk = start_disk + i;
if (disk >= conf->raid_disks)
disk -= conf->raid_disks;
@@ -465,6 +489,35 @@
/* This is a reasonable device to use. It might
* even be best.
*/
+ if (is_badblock(rdev, this_sector, sectors,
+ &first_bad, &bad_sectors)) {
+ if (best_dist < MaxSector)
+ /* already have a better device */
+ continue;
+ if (first_bad <= this_sector) {
+ /* cannot read here. If this is the 'primary'
+ * device, then we must not read beyond
+ * bad_sectors from another device..
+ */
+ bad_sectors -= (this_sector - first_bad);
+ if (choose_first && sectors > bad_sectors)
+ sectors = bad_sectors;
+ if (best_good_sectors > sectors)
+ best_good_sectors = sectors;
+
+ } else {
+ sector_t good_sectors = first_bad - this_sector;
+ if (good_sectors > best_good_sectors) {
+ best_good_sectors = good_sectors;
+ best_disk = disk;
+ }
+ if (choose_first)
+ break;
+ }
+ continue;
+ } else
+ best_good_sectors = sectors;
+
dist = abs(this_sector - conf->mirrors[disk].head_position);
if (choose_first
/* Don't change to another disk for sequential reads */
@@ -493,10 +546,12 @@
rdev_dec_pending(rdev, conf->mddev);
goto retry;
}
+ sectors = best_good_sectors;
conf->next_seq_sect = this_sector + sectors;
conf->last_used = best_disk;
}
rcu_read_unlock();
+ *max_sectors = sectors;
return best_disk;
}
@@ -763,11 +818,25 @@
r1_bio->mddev = mddev;
r1_bio->sector = bio->bi_sector;
+ /* We might need to issue multiple reads to different
+ * devices if there are bad blocks around, so we keep
+ * track of the number of reads in bio->bi_phys_segments.
+ * If this is 0, there is only one r1_bio and no locking
+ * will be needed when requests complete. If it is
+ * non-zero, then it is the number of not-completed requests.
+ */
+ bio->bi_phys_segments = 0;
+ clear_bit(BIO_SEG_VALID, &bio->bi_flags);
+
if (rw == READ) {
/*
* read balancing logic:
*/
- int rdisk = read_balance(conf, r1_bio);
+ int max_sectors;
+ int rdisk;
+
+read_again:
+ rdisk = read_balance(conf, r1_bio, &max_sectors);
if (rdisk < 0) {
/* couldn't find anywhere to read from */
@@ -788,6 +857,8 @@
r1_bio->read_disk = rdisk;
read_bio = bio_clone_mddev(bio, GFP_NOIO, mddev);
+ md_trim_bio(read_bio, r1_bio->sector - bio->bi_sector,
+ max_sectors);
r1_bio->bios[rdisk] = read_bio;
@@ -797,7 +868,38 @@
read_bio->bi_rw = READ | do_sync;
read_bio->bi_private = r1_bio;
- generic_make_request(read_bio);
+ if (max_sectors < r1_bio->sectors) {
+ /* could not read all from this device, so we will
+ * need another r1_bio.
+ */
+ int sectors_handled;
+
+ sectors_handled = (r1_bio->sector + max_sectors
+ - bio->bi_sector);
+ r1_bio->sectors = max_sectors;
+ spin_lock_irq(&conf->device_lock);
+ if (bio->bi_phys_segments == 0)
+ bio->bi_phys_segments = 2;
+ else
+ bio->bi_phys_segments++;
+ spin_unlock_irq(&conf->device_lock);
+ /* Cannot call generic_make_request directly
+ * as that will be queued in __make_request
+ * and subsequent mempool_alloc might block waiting
+ * for it. So hand bio over to raid1d.
+ */
+ reschedule_retry(r1_bio);
+
+ r1_bio = mempool_alloc(conf->r1bio_pool, GFP_NOIO);
+
+ r1_bio->master_bio = bio;
+ r1_bio->sectors = (bio->bi_size >> 9) - sectors_handled;
+ r1_bio->state = 0;
+ r1_bio->mddev = mddev;
+ r1_bio->sector = bio->bi_sector + sectors_handled;
+ goto read_again;
+ } else
+ generic_make_request(read_bio);
return 0;
}
@@ -849,8 +951,6 @@
goto retry_write;
}
- BUG_ON(targets == 0); /* we never fail the last device */
-
if (targets < conf->raid_disks) {
/* array is degraded, we will not clear the bitmap
* on I/O completion (see raid1_end_write_request) */
@@ -1425,7 +1525,7 @@
*
* 1. Retries failed read operations on working mirrors.
* 2. Updates the raid superblock when problems encounter.
- * 3. Performs writes following reads for array syncronising.
+ * 3. Performs writes following reads for array synchronising.
*/
static void fix_read_error(conf_t *conf, int read_disk,
@@ -1448,9 +1548,14 @@
* which is the thread that might remove
* a device. If raid1d ever becomes multi-threaded....
*/
+ sector_t first_bad;
+ int bad_sectors;
+
rdev = conf->mirrors[d].rdev;
if (rdev &&
test_bit(In_sync, &rdev->flags) &&
+ is_badblock(rdev, sect, s,
+ &first_bad, &bad_sectors) == 0 &&
sync_page_io(rdev, sect, s<<9,
conf->tmppage, READ, false))
success = 1;
@@ -1546,9 +1651,11 @@
conf = mddev->private;
if (test_bit(R1BIO_IsSync, &r1_bio->state))
sync_request_write(mddev, r1_bio);
- else {
+ else if (test_bit(R1BIO_ReadError, &r1_bio->state)) {
int disk;
+ int max_sectors;
+ clear_bit(R1BIO_ReadError, &r1_bio->state);
/* we got a read error. Maybe the drive is bad. Maybe just
* the block and we can fix it.
* We freeze all other IO, and try reading the block from
@@ -1568,21 +1675,28 @@
conf->mirrors[r1_bio->read_disk].rdev);
bio = r1_bio->bios[r1_bio->read_disk];
- if ((disk=read_balance(conf, r1_bio)) == -1) {
+ bdevname(bio->bi_bdev, b);
+read_more:
+ disk = read_balance(conf, r1_bio, &max_sectors);
+ if (disk == -1) {
printk(KERN_ALERT "md/raid1:%s: %s: unrecoverable I/O"
" read error for block %llu\n",
- mdname(mddev),
- bdevname(bio->bi_bdev,b),
+ mdname(mddev), b,
(unsigned long long)r1_bio->sector);
raid_end_bio_io(r1_bio);
} else {
const unsigned long do_sync = r1_bio->master_bio->bi_rw & REQ_SYNC;
- r1_bio->bios[r1_bio->read_disk] =
- mddev->ro ? IO_BLOCKED : NULL;
+ if (bio) {
+ r1_bio->bios[r1_bio->read_disk] =
+ mddev->ro ? IO_BLOCKED : NULL;
+ bio_put(bio);
+ }
r1_bio->read_disk = disk;
- bio_put(bio);
bio = bio_clone_mddev(r1_bio->master_bio,
GFP_NOIO, mddev);
+ md_trim_bio(bio,
+ r1_bio->sector - bio->bi_sector,
+ max_sectors);
r1_bio->bios[r1_bio->read_disk] = bio;
rdev = conf->mirrors[disk].rdev;
printk_ratelimited(
@@ -1597,8 +1711,44 @@
bio->bi_end_io = raid1_end_read_request;
bio->bi_rw = READ | do_sync;
bio->bi_private = r1_bio;
- generic_make_request(bio);
+ if (max_sectors < r1_bio->sectors) {
+ /* Drat - have to split this up more */
+ struct bio *mbio = r1_bio->master_bio;
+ int sectors_handled =
+ r1_bio->sector + max_sectors
+ - mbio->bi_sector;
+ r1_bio->sectors = max_sectors;
+ spin_lock_irq(&conf->device_lock);
+ if (mbio->bi_phys_segments == 0)
+ mbio->bi_phys_segments = 2;
+ else
+ mbio->bi_phys_segments++;
+ spin_unlock_irq(&conf->device_lock);
+ generic_make_request(bio);
+ bio = NULL;
+
+ r1_bio = mempool_alloc(conf->r1bio_pool,
+ GFP_NOIO);
+
+ r1_bio->master_bio = mbio;
+ r1_bio->sectors = (mbio->bi_size >> 9)
+ - sectors_handled;
+ r1_bio->state = 0;
+ set_bit(R1BIO_ReadError,
+ &r1_bio->state);
+ r1_bio->mddev = mddev;
+ r1_bio->sector = mbio->bi_sector
+ + sectors_handled;
+
+ goto read_more;
+ } else
+ generic_make_request(bio);
}
+ } else {
+ /* just a partial read to be scheduled from separate
+ * context
+ */
+ generic_make_request(r1_bio->bios[r1_bio->read_disk]);
}
cond_resched();
}