dm: support non power of two target max_io_len
Remove the restriction that limits a target's specified maximum incoming
I/O size to be a power of 2.
Rename this setting from 'split_io' to the less-ambiguous 'max_io_len'.
Change it from sector_t to uint32_t, which is plenty big enough, and
introduce a wrapper function dm_set_target_max_io_len() to set it.
Use sector_div() to process it now that it is not necessarily a power of 2.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index 017c34d..858a8b7 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -353,6 +353,7 @@
{
unsigned i, rebuild_cnt = 0;
unsigned long value, region_size = 0;
+ sector_t max_io_len;
char *key;
/*
@@ -522,14 +523,12 @@
return -EINVAL;
if (rs->md.chunk_sectors)
- rs->ti->split_io = rs->md.chunk_sectors;
+ max_io_len = rs->md.chunk_sectors;
else
- rs->ti->split_io = region_size;
+ max_io_len = region_size;
- if (rs->md.chunk_sectors)
- rs->ti->split_io = rs->md.chunk_sectors;
- else
- rs->ti->split_io = region_size;
+ if (dm_set_target_max_io_len(rs->ti, max_io_len))
+ return -EINVAL;
/* Assume there are no metadata devices until the drives are parsed */
rs->md.persistent = 0;
diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index b58b7a3..819ccba 100644
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -1081,7 +1081,11 @@
}
ti->private = ms;
- ti->split_io = dm_rh_get_region_size(ms->rh);
+
+ r = dm_set_target_max_io_len(ti, dm_rh_get_region_size(ms->rh));
+ if (r)
+ goto err_free_context;
+
ti->num_flush_requests = 1;
ti->num_discard_requests = 1;
ti->discard_zeroes_data_unsupported = 1;
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index a228c20..6c0f3e3 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -691,7 +691,7 @@
* Return a minimum chunk size of all snapshots that have the specified origin.
* Return zero if the origin has no snapshots.
*/
-static sector_t __minimum_chunk_size(struct origin *o)
+static uint32_t __minimum_chunk_size(struct origin *o)
{
struct dm_snapshot *snap;
unsigned chunk_size = 0;
@@ -701,7 +701,7 @@
chunk_size = min_not_zero(chunk_size,
snap->store->chunk_size);
- return chunk_size;
+ return (uint32_t) chunk_size;
}
/*
@@ -1172,7 +1172,10 @@
ti->error = "Chunk size not set";
goto bad_read_metadata;
}
- ti->split_io = s->store->chunk_size;
+
+ r = dm_set_target_max_io_len(ti, s->store->chunk_size);
+ if (r)
+ goto bad_read_metadata;
return 0;
@@ -1239,7 +1242,7 @@
snap_dest->store->snap = snap_dest;
snap_src->store->snap = snap_src;
- snap_dest->ti->split_io = snap_dest->store->chunk_size;
+ snap_dest->ti->max_io_len = snap_dest->store->chunk_size;
snap_dest->valid = snap_src->valid;
/*
@@ -1817,9 +1820,9 @@
up_write(&s->lock);
}
-static sector_t get_origin_minimum_chunksize(struct block_device *bdev)
+static uint32_t get_origin_minimum_chunksize(struct block_device *bdev)
{
- sector_t min_chunksize;
+ uint32_t min_chunksize;
down_read(&_origins_lock);
min_chunksize = __minimum_chunk_size(__lookup_origin(bdev));
@@ -1838,9 +1841,9 @@
snapshot_resume(ti);
/*
- * snapshot-merge acts as an origin, so set ti->split_io
+ * snapshot-merge acts as an origin, so set ti->max_io_len
*/
- ti->split_io = get_origin_minimum_chunksize(s->origin->bdev);
+ ti->max_io_len = get_origin_minimum_chunksize(s->origin->bdev);
start_merge(s);
}
@@ -2073,12 +2076,12 @@
struct origin *o;
/*
- * The origin's __minimum_chunk_size() got stored in split_io
+ * The origin's __minimum_chunk_size() got stored in max_io_len
* by snapshot_merge_resume().
*/
down_read(&_origins_lock);
o = __lookup_origin(merging_snap->origin->bdev);
- for (n = 0; n < size; n += merging_snap->ti->split_io)
+ for (n = 0; n < size; n += merging_snap->ti->max_io_len)
if (__origin_write(&o->snapshots, sector + n, NULL) ==
DM_MAPIO_SUBMITTED)
must_wait = 1;
@@ -2138,14 +2141,14 @@
}
/*
- * Set the target "split_io" field to the minimum of all the snapshots'
+ * Set the target "max_io_len" field to the minimum of all the snapshots'
* chunk sizes.
*/
static void origin_resume(struct dm_target *ti)
{
struct dm_dev *dev = ti->private;
- ti->split_io = get_origin_minimum_chunksize(dev->bdev);
+ ti->max_io_len = get_origin_minimum_chunksize(dev->bdev);
}
static int origin_status(struct dm_target *ti, status_type_t type, char *result,
diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index 6931bd1..992c9d4 100644
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -165,7 +165,10 @@
else
sc->stripes_shift = __ffs(stripes);
- ti->split_io = chunk_size;
+ r = dm_set_target_max_io_len(ti, chunk_size);
+ if (r)
+ return r;
+
ti->num_flush_requests = stripes;
ti->num_discard_requests = stripes;
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index e89f8e7..350bcf4 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -2628,7 +2628,10 @@
goto bad_thin_open;
}
- ti->split_io = tc->pool->sectors_per_block;
+ r = dm_set_target_max_io_len(ti, tc->pool->sectors_per_block);
+ if (r)
+ goto bad_thin_open;
+
ti->num_flush_requests = 1;
/* In case the pool supports discards, pass them on. */
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index e24143c..415c280 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -968,22 +968,41 @@
static sector_t max_io_len(sector_t sector, struct dm_target *ti)
{
sector_t len = max_io_len_target_boundary(sector, ti);
+ sector_t offset, max_len;
/*
- * Does the target need to split even further ?
+ * Does the target need to split even further?
*/
- if (ti->split_io) {
- sector_t boundary;
- sector_t offset = dm_target_offset(ti, sector);
- boundary = ((offset + ti->split_io) & ~(ti->split_io - 1))
- - offset;
- if (len > boundary)
- len = boundary;
+ if (ti->max_io_len) {
+ offset = dm_target_offset(ti, sector);
+ if (unlikely(ti->max_io_len & (ti->max_io_len - 1)))
+ max_len = sector_div(offset, ti->max_io_len);
+ else
+ max_len = offset & (ti->max_io_len - 1);
+ max_len = ti->max_io_len - max_len;
+
+ if (len > max_len)
+ len = max_len;
}
return len;
}
+int dm_set_target_max_io_len(struct dm_target *ti, sector_t len)
+{
+ if (len > UINT_MAX) {
+ DMERR("Specified maximum size of target IO (%llu) exceeds limit (%u)",
+ (unsigned long long)len, UINT_MAX);
+ ti->error = "Maximum size of target IO is too large";
+ return -EINVAL;
+ }
+
+ ti->max_io_len = (uint32_t) len;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(dm_set_target_max_io_len);
+
static void __map_bio(struct dm_target *ti, struct bio *clone,
struct dm_target_io *tio)
{
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index d70cbb2..b19c1e1 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -186,8 +186,8 @@
sector_t begin;
sector_t len;
- /* Always a power of 2 */
- sector_t split_io;
+ /* If non-zero, maximum size of I/O submitted to a target. */
+ uint32_t max_io_len;
/*
* A number of zero-length barrier requests that will be submitted
@@ -358,6 +358,11 @@
int dm_table_complete(struct dm_table *t);
/*
+ * Target may require that it is never sent I/O larger than len.
+ */
+int __must_check dm_set_target_max_io_len(struct dm_target *ti, sector_t len);
+
+/*
* Table reference counting.
*/
struct dm_table *dm_get_live_table(struct mapped_device *md);
diff --git a/include/linux/dm-ioctl.h b/include/linux/dm-ioctl.h
index 75fd5573..3ece4ee 100644
--- a/include/linux/dm-ioctl.h
+++ b/include/linux/dm-ioctl.h
@@ -268,8 +268,8 @@
#define DM_VERSION_MAJOR 4
#define DM_VERSION_MINOR 22
-#define DM_VERSION_PATCHLEVEL 0
-#define DM_VERSION_EXTRA "-ioctl (2011-10-19)"
+#define DM_VERSION_PATCHLEVEL 1
+#define DM_VERSION_EXTRA "-ioctl (2012-06-01)"
/* Status bits */
#define DM_READONLY_FLAG (1 << 0) /* In/Out */