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authorJoe Thornber <ejt@redhat.com>2013-05-10 14:37:21 +0100
committerAlasdair G Kergon <agk@redhat.com>2013-05-10 14:37:21 +0100
commitac8c3f3df65e487bbcabf274eeeb9cd222f5da1e (patch)
treee1ab6d4662834bbbf248b1ad6224c9b7c3faa15e /drivers
parent2fc48021f4afdd109b9e52b6eef5db89ca80bac7 (diff)
downloadlinux-linaro-stable-ac8c3f3df65e487bbcabf274eeeb9cd222f5da1e.tar.gz
dm thin: generate event when metadata threshold passed
Generate a dm event when the amount of remaining thin pool metadata space falls below a certain level. The threshold is taken to be a quarter of the size of the metadata device with a minimum threshold of 4MB. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/md/dm-thin-metadata.c14
-rw-r--r--drivers/md/dm-thin-metadata.h6
-rw-r--r--drivers/md/dm-thin.c38
3 files changed, 58 insertions, 0 deletions
diff --git a/drivers/md/dm-thin-metadata.c b/drivers/md/dm-thin-metadata.c
index f553ed66603c..60bce435f4fa 100644
--- a/drivers/md/dm-thin-metadata.c
+++ b/drivers/md/dm-thin-metadata.c
@@ -1696,3 +1696,17 @@ void dm_pool_metadata_read_only(struct dm_pool_metadata *pmd)
dm_bm_set_read_only(pmd->bm);
up_write(&pmd->root_lock);
}
+
+int dm_pool_register_metadata_threshold(struct dm_pool_metadata *pmd,
+ dm_block_t threshold,
+ dm_sm_threshold_fn fn,
+ void *context)
+{
+ int r;
+
+ down_write(&pmd->root_lock);
+ r = dm_sm_register_threshold_callback(pmd->metadata_sm, threshold, fn, context);
+ up_write(&pmd->root_lock);
+
+ return r;
+}
diff --git a/drivers/md/dm-thin-metadata.h b/drivers/md/dm-thin-metadata.h
index ef8dd709e34e..845ebbe589a9 100644
--- a/drivers/md/dm-thin-metadata.h
+++ b/drivers/md/dm-thin-metadata.h
@@ -8,6 +8,7 @@
#define DM_THIN_METADATA_H
#include "persistent-data/dm-block-manager.h"
+#include "persistent-data/dm-space-map.h"
#define THIN_METADATA_BLOCK_SIZE 4096
@@ -193,6 +194,11 @@ int dm_pool_resize_metadata_dev(struct dm_pool_metadata *pmd, dm_block_t new_siz
*/
void dm_pool_metadata_read_only(struct dm_pool_metadata *pmd);
+int dm_pool_register_metadata_threshold(struct dm_pool_metadata *pmd,
+ dm_block_t threshold,
+ dm_sm_threshold_fn fn,
+ void *context);
+
/*----------------------------------------------------------------*/
#endif
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index f4632f97bd7b..759cffc45cab 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -1281,6 +1281,10 @@ static void process_bio_fail(struct thin_c *tc, struct bio *bio)
bio_io_error(bio);
}
+/*
+ * FIXME: should we also commit due to size of transaction, measured in
+ * metadata blocks?
+ */
static int need_commit_due_to_time(struct pool *pool)
{
return jiffies < pool->last_commit_jiffies ||
@@ -1909,6 +1913,16 @@ static int parse_pool_features(struct dm_arg_set *as, struct pool_features *pf,
return r;
}
+static void metadata_low_callback(void *context)
+{
+ struct pool *pool = context;
+
+ DMWARN("%s: reached low water mark for metadata device: sending event.",
+ dm_device_name(pool->pool_md));
+
+ dm_table_event(pool->ti->table);
+}
+
static sector_t get_metadata_dev_size(struct block_device *bdev)
{
sector_t metadata_dev_size = i_size_read(bdev->bd_inode) >> SECTOR_SHIFT;
@@ -1933,6 +1947,23 @@ static dm_block_t get_metadata_dev_size_in_blocks(struct block_device *bdev)
}
/*
+ * When a metadata threshold is crossed a dm event is triggered, and
+ * userland should respond by growing the metadata device. We could let
+ * userland set the threshold, like we do with the data threshold, but I'm
+ * not sure they know enough to do this well.
+ */
+static dm_block_t calc_metadata_threshold(struct pool_c *pt)
+{
+ /*
+ * 4M is ample for all ops with the possible exception of thin
+ * device deletion which is harmless if it fails (just retry the
+ * delete after you've grown the device).
+ */
+ dm_block_t quarter = get_metadata_dev_size_in_blocks(pt->metadata_dev->bdev) / 4;
+ return min((dm_block_t)1024ULL /* 4M */, quarter);
+}
+
+/*
* thin-pool <metadata dev> <data dev>
* <data block size (sectors)>
* <low water mark (blocks)>
@@ -2065,6 +2096,13 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
}
ti->private = pt;
+ r = dm_pool_register_metadata_threshold(pt->pool->pmd,
+ calc_metadata_threshold(pt),
+ metadata_low_callback,
+ pool);
+ if (r)
+ goto out_free_pt;
+
pt->callbacks.congested_fn = pool_is_congested;
dm_table_add_target_callbacks(ti->table, &pt->callbacks);