[PATCH v3 14/16] bcache: add sysfs file to display feature sets information of cache set

colyli
2020-07-15T14:31:02Z

A new sysfs file /sys/fs/bcache/<cache set UUID>/internal/feature_sets
is added by this patch, to display feature sets information of the cache
set.

Now only an incompat feature 'large_bucket' added in bcache, the sysfs
file content is:
feature_incompat: [large_bucket]
string large_bucket means the running bcache drive supports incompat
feature 'large_bucket', the wrapping [] means the 'large_bucket' feature
is currently enabled on this cache set.

This patch is ready to display compat and ro_compat features, in future
once bcache code implements such feature sets, the according feature
strings will be displayed in this sysfs file too.

Signed-off-by: Coly Li <colyli@suse.de>
---
drivers/md/bcache/Makefile | 2 +-
drivers/md/bcache/features.c | 48 ++++++++++++++++++++++++++++++++++++
drivers/md/bcache/features.h | 3 +++
drivers/md/bcache/sysfs.c | 6 +++++
4 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/drivers/md/bcache/Makefile b/drivers/md/bcache/Makefile
index fd714628da6a..5b87e59676b8 100644
--- a/drivers/md/bcache/Makefile
+++ b/drivers/md/bcache/Makefile
@@ -4,4 +4,4 @@ obj-$(CONFIG_BCACHE) += bcache.o

bcache-y := alloc.o bset.o btree.o closure.o debug.o extents.o\
io.o journal.o movinggc.o request.o stats.o super.o sysfs.o trace.o\
- util.o writeback.o
+ util.o writeback.o features.o
diff --git a/drivers/md/bcache/features.c b/drivers/md/bcache/features.c
index ba53944bb390..5c601635e11c 100644
--- a/drivers/md/bcache/features.c
+++ b/drivers/md/bcache/features.c
@@ -8,6 +8,7 @@
*/
#include <linux/bcache.h>
#include "bcache.h"
+#include "features.h"

struct feature {
int compat;
@@ -20,3 +21,50 @@ static struct feature feature_list[] = {
"large_bucket"},
{0, 0, 0 },
};
+
+#define compose_feature_string(type, head) \
+({ \
+ struct feature *f; \
+ bool first = true; \
+ \
+ for (f = &feature_list[0]; f->compat != 0; f++) { \
+ if (f->compat != BCH_FEATURE_ ## type) \
+ continue; \
+ if (BCH_HAS_ ## type ## _FEATURE(&c->sb, f->mask)) { \
+ if (first) { \
+ out += snprintf(out, buf + size - out, \
+ "%s%s", head, ": ["); \
+ } else { \
+ out += snprintf(out, buf + size - out, \
+ " ["); \
+ } \
+ } else { \
+ if (first) \
+ out += snprintf(out, buf + size - out, \
+ "%s%s", head, ": "); \
+ else \
+ out += snprintf(out, buf + size - out, \
+ " "); \
+ } \
+ \
+ out += snprintf(out, buf + size - out, "%s", f->string);\
+ \
+ if (BCH_HAS_ ## type ## _FEATURE(&c->sb, f->mask)) \
+ out += snprintf(out, buf + size - out, "]"); \
+ \
+ first = false; \
+ } \
+ if (!first) \
+ out += snprintf(out, buf + size - out, "\n"); \
+})
+
+int bch_print_cache_set_feature_set(struct cache_set *c, char *buf, int size)
+{
+ char *out = buf;
+
+ compose_feature_string(COMPAT, "feature_compat");
+ compose_feature_string(RO_COMPAT, "feature_ro_compat");
+ compose_feature_string(INCOMPAT, "feature_incompat");
+
+ return out - buf;
+}
diff --git a/drivers/md/bcache/features.h b/drivers/md/bcache/features.h
index dca052cf5203..350a4f413136 100644
--- a/drivers/md/bcache/features.h
+++ b/drivers/md/bcache/features.h
@@ -78,4 +78,7 @@ static inline void bch_clear_feature_##name(struct cache_sb *sb) \
}

BCH_FEATURE_INCOMPAT_FUNCS(large_bucket, LARGE_BUCKET);
+
+int bch_print_cache_set_feature_set(struct cache_set *c, char *buf, int size);
+
#endif
diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
index 0dadec5a78f6..e3633f06d43b 100644
--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -11,6 +11,7 @@
#include "btree.h"
#include "request.h"
#include "writeback.h"
+#include "features.h"

#include <linux/blkdev.h>
#include <linux/sort.h>
@@ -88,6 +89,7 @@ read_attribute(btree_used_percent);
read_attribute(average_key_size);
read_attribute(dirty_data);
read_attribute(bset_tree_stats);
+read_attribute(feature_sets);

read_attribute(state);
read_attribute(cache_read_races);
@@ -779,6 +781,9 @@ SHOW(__bch_cache_set)
if (attr == &sysfs_bset_tree_stats)
return bch_bset_print_stats(c, buf);

+ if (attr == &sysfs_feature_sets)
+ return bch_print_cache_set_feature_set(c, buf, PAGE_SIZE);
+
return 0;
}
SHOW_LOCKED(bch_cache_set)
@@ -987,6 +992,7 @@ static struct attribute *bch_cache_set_internal_files[] = {
&sysfs_io_disable,
&sysfs_cutoff_writeback,
&sysfs_cutoff_writeback_sync,
+ &sysfs_feature_sets,
NULL
};
KTYPE(bch_cache_set_internal);
--
2.26.2