[dm-devel] [LVM PATCH 4/4] cache: Add device-mapper interface for retrieving a cache's status
Jonathan Brassow
jbrassow at redhat.com
Thu Jan 23 15:05:48 UTC 2014
This patch defines a structure for holding all of the device-mapper
cache target's status information. The associated function provides
an easy way for higher levels (LVM) to consume the information.
This patch finishes the device-mapper interface for the cache and
cachepool segment types (i.e. the cache target).
---
libdm/libdevmapper.h | 35 +++++++++++++-
libdm/libdm-deptree.c | 130 +++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 164 insertions(+), 1 deletions(-)
diff --git a/libdm/libdevmapper.h b/libdm/libdevmapper.h
index ae9a91a..670c5e09 100644
--- a/libdm/libdevmapper.h
+++ b/libdm/libdevmapper.h
@@ -1,6 +1,6 @@
/*
* Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
- * Copyright (C) 2004-2013 Red Hat, Inc. All rights reserved.
+ * Copyright (C) 2004-2014 Red Hat, Inc. All rights reserved.
*
* This file is part of the device-mapper userspace tools.
*
@@ -294,6 +294,39 @@ struct dm_status_raid {
int dm_get_status_raid(struct dm_pool *mem, const char *params,
struct dm_status_raid **status);
+struct dm_status_cache {
+ uint64_t version; /* zero for now */
+
+ uint32_t metadata_block_size; /* in 512B sectors */
+ uint32_t block_size; /* AKA 'chunk_size' */
+
+ uint64_t metadata_used_blocks;
+ uint64_t metadata_total_blocks;
+
+ uint64_t used_blocks;
+ uint64_t dirty_blocks;
+ uint64_t total_blocks;
+
+ uint64_t read_hits;
+ uint64_t read_misses;
+ uint64_t write_hits;
+ uint64_t write_misses;
+
+ uint64_t demotions;
+ uint64_t promotions;
+
+ uint32_t feature_flags;
+
+ int core_argc;
+ char **core_argv;
+
+ char *policy_name;
+ int policy_argc;
+ char **policy_argv;
+};
+
+int dm_get_status_cache(struct dm_pool *mem, const char *params,
+ struct dm_status_cache **status);
/*
* Snapshot target's format:
diff --git a/libdm/libdm-deptree.c b/libdm/libdm-deptree.c
index d3f6640..8e507c9 100644
--- a/libdm/libdm-deptree.c
+++ b/libdm/libdm-deptree.c
@@ -3249,6 +3249,136 @@ int dm_tree_node_add_cache_target(struct dm_tree_node *node,
return 1;
}
+static const char *advance_to_next_word(const char *str, int count)
+{
+ int i;
+ const char *p;
+
+ for (p = str, i = 0; i < count; i++, p++)
+ if (!(p = strchr(p, ' ')))
+ return NULL;
+
+ return p;
+}
+
+/*
+ * <#used metadata blocks>/<#total metadata blocks> <#read hits> <#read misses>
+ * <#write hits> <#write misses> <#demotions> <#promotions> <#blocks in cache>
+ * <#dirty> <#features> <features>* <#core args> <core args>* <#policy args>
+ * <policy args>*
+ *
+ * #used metadata blocks : Number of metadata blocks used
+ * #total metadata blocks : Total number of metadata blocks
+ * #read hits : Number of times a READ bio has been mapped
+ * to the cache
+ * #read misses : Number of times a READ bio has been mapped
+ * to the origin
+ * #write hits : Number of times a WRITE bio has been mapped
+ * to the cache
+ * #write misses : Number of times a WRITE bio has been
+ * mapped to the origin
+ * #demotions : Number of times a block has been removed
+ * from the cache
+ * #promotions : Number of times a block has been moved to
+ * the cache
+ * #blocks in cache : Number of blocks resident in the cache
+ * #dirty : Number of blocks in the cache that differ
+ * from the origin
+ * #feature args : Number of feature args to follow
+ * feature args : 'writethrough' (optional)
+ * #core args : Number of core arguments (must be even)
+ * core args : Key/value pairs for tuning the core
+ * e.g. migration_threshold
+ * #policy args : Number of policy arguments to follow (must be even)
+ * policy args : Key/value pairs
+ * e.g. 'sequential_threshold 1024
+ */
+int dm_get_status_cache(struct dm_pool *mem, const char *params,
+ struct dm_status_cache **status)
+{
+ int i, feature_argc;
+ char *str;
+ const char *p, *pp;
+ struct dm_status_cache *s;
+
+ if (!(s = dm_pool_zalloc(mem, sizeof(struct dm_status_cache))))
+ return_0;
+
+ /* Read in args that have definitive placement */
+ if (sscanf(params,
+ " %" PRIu32
+ " %" PRIu64 "/%" PRIu64
+ " %" PRIu32
+ " %" PRIu64 "/%" PRIu64
+ " %" PRIu64 " %" PRIu64
+ " %" PRIu64 " %" PRIu64
+ " %" PRIu64 " %" PRIu64
+ " %" PRIu64
+ " %d",
+ &s->metadata_block_size,
+ &s->metadata_used_blocks, &s->metadata_total_blocks,
+ &s->block_size, /* AKA, chunk_size */
+ &s->used_blocks, &s->total_blocks,
+ &s->read_hits, &s->read_misses,
+ &s->write_hits, &s->write_misses,
+ &s->demotions, &s->promotions,
+ &s->dirty_blocks,
+ &feature_argc) != 14)
+ goto bad;
+
+ /* Now jump to "features" section */
+ if (!(p = advance_to_next_word(params, 12)))
+ goto bad;
+
+ /* Read in features */
+ for (i = 0; i < feature_argc; i++) {
+ if (!strncmp(p, "writethrough ", 13))
+ s->feature_flags |= DM_CACHE_FEATURE_WRITETHROUGH;
+ else if (!strncmp(p, "writeback ", 10))
+ s->feature_flags |= DM_CACHE_FEATURE_WRITEBACK;
+ else
+ log_error("Unknown feature in status: %s", params);
+
+ if (!(p = advance_to_next_word(p, 1)))
+ goto bad;
+ }
+
+ /* Read in core_args. */
+ if (sscanf(p, "%d ", &s->core_argc) != 1)
+ goto bad;
+ if (s->core_argc &&
+ (!(s->core_argv = dm_pool_zalloc(mem, sizeof(char *) * s->core_argc)) ||
+ !(p = advance_to_next_word(p, 1)) ||
+ !(str = dm_pool_strdup(mem, p)) ||
+ !(p = advance_to_next_word(p, s->core_argc)) ||
+ (dm_split_words(str, s->core_argc, 0, s->core_argv) != s->core_argc)))
+ goto bad;
+
+ /* Read in policy args */
+ pp = p;
+ if (!(p = advance_to_next_word(p, 1)) ||
+ !(s->policy_name = dm_pool_zalloc(mem, (p - pp))))
+ goto bad;
+ if (sscanf(pp, "%s %d", s->policy_name, &s->policy_argc) != 2)
+ goto bad;
+ if (s->policy_argc &&
+ (!(s->policy_argv = dm_pool_zalloc(mem, sizeof(char *) * s->policy_argc)) ||
+ !(p = advance_to_next_word(p, 1)) ||
+ !(str = dm_pool_strdup(mem, p)) ||
+ (dm_split_words(str, s->policy_argc, 0, s->policy_argv) != s->policy_argc)))
+ goto bad;
+
+ *status = s;
+ return 1;
+
+bad:
+ log_error("Failed to parse cache params: %s", params);
+ dm_pool_free(mem, s);
+ *status = NULL;
+
+ return 0;
+}
+
int dm_tree_node_add_replicator_target(struct dm_tree_node *node,
uint64_t size,
const char *rlog_uuid,
--
1.7.7.6
More information about the dm-devel
mailing list