#include "dm.h"
#include "dm-bio-list.h"
+#include "dm-bio-record.h"
#include "dm-io.h"
#include "dm-log.h"
#include "kcopyd.h"
struct bio_list failures;
struct dm_io_client *io_client;
+ mempool_t *read_record_pool;
/* recovery */
region_t nr_regions;
wake(rh->ms);
}
+#define MIN_READ_RECORDS 20
+struct dm_raid1_read_record {
+ struct mirror *m;
+ struct dm_bio_details details;
+};
+
/*
* Every mirror should look like this one.
*/
#define DEFAULT_MIRROR 0
/*
- * This is yucky. We squirrel the mirror_set struct away inside
- * bi_next for write buffers. This is safe since the bh
+ * This is yucky. We squirrel the mirror struct away inside
+ * bi_next for read/write buffers. This is safe since the bh
* doesn't get submitted to the lower levels of block layer.
*/
-static struct mirror_set *bio_get_ms(struct bio *bio)
+static struct mirror *bio_get_m(struct bio *bio)
{
- return (struct mirror_set *) bio->bi_next;
+ return (struct mirror *) bio->bi_next;
}
-static void bio_set_ms(struct bio *bio, struct mirror_set *ms)
+static void bio_set_m(struct bio *bio, struct mirror *m)
{
- bio->bi_next = (struct bio *) ms;
+ bio->bi_next = (struct bio *) m;
}
static struct mirror *get_default_mirror(struct mirror_set *ms)
*---------------------------------------------------------------*/
static struct mirror *choose_mirror(struct mirror_set *ms, sector_t sector)
{
- /* FIXME: add read balancing */
- return get_default_mirror(ms);
+ struct mirror *m = get_default_mirror(ms);
+
+ do {
+ if (likely(!atomic_read(&m->error_count)))
+ return m;
+
+ if (m-- == ms->mirror)
+ m += ms->nr_mirrors;
+ } while (m != get_default_mirror(ms));
+
+ return NULL;
+}
+
+static int default_ok(struct mirror *m)
+{
+ struct mirror *default_mirror = get_default_mirror(m->ms);
+
+ return !atomic_read(&default_mirror->error_count);
+}
+
+static int mirror_available(struct mirror_set *ms, struct bio *bio)
+{
+ region_t region = bio_to_region(&ms->rh, bio);
+
+ if (ms->rh.log->type->in_sync(ms->rh.log, region, 0))
+ return choose_mirror(ms, bio->bi_sector) ? 1 : 0;
+
+ return 0;
}
/*
* remap a buffer to a particular mirror.
*/
-static void map_bio(struct mirror_set *ms, struct mirror *m, struct bio *bio)
+static sector_t map_sector(struct mirror *m, struct bio *bio)
+{
+ return m->offset + (bio->bi_sector - m->ms->ti->begin);
+}
+
+static void map_bio(struct mirror *m, struct bio *bio)
{
bio->bi_bdev = m->dev->bdev;
- bio->bi_sector = m->offset + (bio->bi_sector - ms->ti->begin);
+ bio->bi_sector = map_sector(m, bio);
+}
+
+static void map_region(struct io_region *io, struct mirror *m,
+ struct bio *bio)
+{
+ io->bdev = m->dev->bdev;
+ io->sector = map_sector(m, bio);
+ io->count = bio->bi_size >> 9;
+}
+
+/*-----------------------------------------------------------------
+ * Reads
+ *---------------------------------------------------------------*/
+static void read_callback(unsigned long error, void *context)
+{
+ struct bio *bio = context;
+ struct mirror *m;
+
+ m = bio_get_m(bio);
+ bio_set_m(bio, NULL);
+
+ if (likely(!error)) {
+ bio_endio(bio, 0);
+ return;
+ }
+
+ fail_mirror(m, DM_RAID1_READ_ERROR);
+
+ if (likely(default_ok(m)) || mirror_available(m->ms, bio)) {
+ DMWARN_LIMIT("Read failure on mirror device %s. "
+ "Trying alternative device.",
+ m->dev->name);
+ queue_bio(m->ms, bio, bio_rw(bio));
+ return;
+ }
+
+ DMERR_LIMIT("Read failure on mirror device %s. Failing I/O.",
+ m->dev->name);
+ bio_endio(bio, -EIO);
+}
+
+/* Asynchronous read. */
+static void read_async_bio(struct mirror *m, struct bio *bio)
+{
+ struct io_region io;
+ struct dm_io_request io_req = {
+ .bi_rw = READ,
+ .mem.type = DM_IO_BVEC,
+ .mem.ptr.bvec = bio->bi_io_vec + bio->bi_idx,
+ .notify.fn = read_callback,
+ .notify.context = bio,
+ .client = m->ms->io_client,
+ };
+
+ map_region(&io, m, bio);
+ bio_set_m(bio, m);
+ (void) dm_io(&io_req, 1, &io, NULL);
}
static void do_reads(struct mirror_set *ms, struct bio_list *reads)
while ((bio = bio_list_pop(reads))) {
region = bio_to_region(&ms->rh, bio);
+ m = get_default_mirror(ms);
/*
* We can only read balance if the region is in sync.
*/
- if (rh_in_sync(&ms->rh, region, 1))
+ if (likely(rh_in_sync(&ms->rh, region, 1)))
m = choose_mirror(ms, bio->bi_sector);
- else
- m = get_default_mirror(ms);
+ else if (m && atomic_read(&m->error_count))
+ m = NULL;
- map_bio(ms, m, bio);
- generic_make_request(bio);
+ if (likely(m))
+ read_async_bio(m, bio);
+ else
+ bio_endio(bio, -EIO);
}
}
int should_wake = 0;
unsigned long flags;
- ms = bio_get_ms(bio);
- bio_set_ms(bio, NULL);
+ ms = bio_get_m(bio)->ms;
+ bio_set_m(bio, NULL);
/*
* NOTE: We don't decrement the pending count here,
static void do_write(struct mirror_set *ms, struct bio *bio)
{
unsigned int i;
- struct io_region io[KCOPYD_MAX_REGIONS+1];
+ struct io_region io[ms->nr_mirrors], *dest = io;
struct mirror *m;
struct dm_io_request io_req = {
.bi_rw = WRITE,
.client = ms->io_client,
};
- for (i = 0; i < ms->nr_mirrors; i++) {
- m = ms->mirror + i;
-
- io[i].bdev = m->dev->bdev;
- io[i].sector = m->offset + (bio->bi_sector - ms->ti->begin);
- io[i].count = bio->bi_size >> 9;
- }
+ for (i = 0, m = ms->mirror; i < ms->nr_mirrors; i++, m++)
+ map_region(dest++, m, bio);
- bio_set_ms(bio, ms);
+ /*
+ * Use default mirror because we only need it to retrieve the reference
+ * to the mirror set in write_callback().
+ */
+ bio_set_m(bio, get_default_mirror(ms));
(void) dm_io(&io_req, ms->nr_mirrors, io, NULL);
}
rh_delay(&ms->rh, bio);
while ((bio = bio_list_pop(&nosync))) {
- map_bio(ms, get_default_mirror(ms), bio);
+ map_bio(get_default_mirror(ms), bio);
generic_make_request(bio);
}
}
atomic_set(&ms->suspend, 0);
atomic_set(&ms->default_mirror, DEFAULT_MIRROR);
+ len = sizeof(struct dm_raid1_read_record);
+ ms->read_record_pool = mempool_create_kmalloc_pool(MIN_READ_RECORDS,
+ len);
+ if (!ms->read_record_pool) {
+ ti->error = "Error creating mirror read_record_pool";
+ kfree(ms);
+ return NULL;
+ }
+
ms->io_client = dm_io_client_create(DM_IO_PAGES);
if (IS_ERR(ms->io_client)) {
ti->error = "Error creating dm_io client";
+ mempool_destroy(ms->read_record_pool);
kfree(ms);
return NULL;
}
if (rh_init(&ms->rh, ms, dl, region_size, ms->nr_regions)) {
ti->error = "Error creating dirty region hash";
dm_io_client_destroy(ms->io_client);
+ mempool_destroy(ms->read_record_pool);
kfree(ms);
return NULL;
}
dm_io_client_destroy(ms->io_client);
rh_exit(&ms->rh);
+ mempool_destroy(ms->read_record_pool);
kfree(ms);
}
int r, rw = bio_rw(bio);
struct mirror *m;
struct mirror_set *ms = ti->private;
-
- map_context->ll = bio_to_region(&ms->rh, bio);
+ struct dm_raid1_read_record *read_record = NULL;
if (rw == WRITE) {
+ /* Save region for mirror_end_io() handler */
+ map_context->ll = bio_to_region(&ms->rh, bio);
queue_bio(ms, bio, rw);
return DM_MAPIO_SUBMITTED;
}
if (r < 0 && r != -EWOULDBLOCK)
return r;
- if (r == -EWOULDBLOCK) /* FIXME: ugly */
- r = DM_MAPIO_SUBMITTED;
-
/*
- * We don't want to fast track a recovery just for a read
- * ahead. So we just let it silently fail.
- * FIXME: get rid of this.
+ * If region is not in-sync queue the bio.
*/
- if (!r && rw == READA)
- return -EIO;
+ if (!r || (r == -EWOULDBLOCK)) {
+ if (rw == READA)
+ return -EWOULDBLOCK;
- if (!r) {
- /* Pass this io over to the daemon */
queue_bio(ms, bio, rw);
return DM_MAPIO_SUBMITTED;
}
+ /*
+ * The region is in-sync and we can perform reads directly.
+ * Store enough information so we can retry if it fails.
+ */
m = choose_mirror(ms, bio->bi_sector);
- if (!m)
+ if (unlikely(!m))
return -EIO;
- map_bio(ms, m, bio);
+ read_record = mempool_alloc(ms->read_record_pool, GFP_NOIO);
+ if (likely(read_record)) {
+ dm_bio_record(&read_record->details, bio);
+ map_context->ptr = read_record;
+ read_record->m = m;
+ }
+
+ map_bio(m, bio);
+
return DM_MAPIO_REMAPPED;
}
{
int rw = bio_rw(bio);
struct mirror_set *ms = (struct mirror_set *) ti->private;
- region_t region = map_context->ll;
+ struct mirror *m = NULL;
+ struct dm_bio_details *bd = NULL;
+ struct dm_raid1_read_record *read_record = map_context->ptr;
/*
* We need to dec pending if this was a write.
*/
- if (rw == WRITE)
- rh_dec(&ms->rh, region);
+ if (rw == WRITE) {
+ rh_dec(&ms->rh, map_context->ll);
+ return error;
+ }
- return 0;
+ if (error == -EOPNOTSUPP)
+ goto out;
+
+ if ((error == -EWOULDBLOCK) && bio_rw_ahead(bio))
+ goto out;
+
+ if (unlikely(error)) {
+ if (!read_record) {
+ /*
+ * There wasn't enough memory to record necessary
+ * information for a retry or there was no other
+ * mirror in-sync.
+ */
+ DMERR_LIMIT("Mirror read failed from %s.",
+ m->dev->name);
+ return -EIO;
+ }
+ DMERR("Mirror read failed from %s. Trying alternative device.",
+ m->dev->name);
+
+ m = read_record->m;
+ fail_mirror(m, DM_RAID1_READ_ERROR);
+
+ /*
+ * A failed read is requeued for another attempt using an intact
+ * mirror.
+ */
+ if (default_ok(m) || mirror_available(ms, bio)) {
+ bd = &read_record->details;
+
+ dm_bio_restore(bd, bio);
+ mempool_free(read_record, ms->read_record_pool);
+ map_context->ptr = NULL;
+ queue_bio(ms, bio, rw);
+ return 1;
+ }
+ DMERR("All replicated volumes dead, failing I/O");
+ }
+
+out:
+ if (read_record) {
+ mempool_free(read_record, ms->read_record_pool);
+ map_context->ptr = NULL;
+ }
+
+ return error;
}
static void mirror_presuspend(struct dm_target *ti)
projects / linux-2.6-omap-h63xx.git / commitdiff