bcache: add sysfs file to display feature sets information of cache set

The following three sysfs files are created to display according feature
set information of bcache:
	/sys/fs/bcache/<cache set UUID>/internal/feature_compat
	/sys/fs/bcache/<cache set UUID>/internal/feature_ro_compat
	/sys/fs/bcache/<cache set UUID>/internal/feature_incompat
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:
        [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 their sysfs files too.

Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/md/bcache/Makefile b/drivers/md/bcache/Makefile
index fd71462..5b87e59 100644 (file)
--- 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 ba53944..4442df4 100644 (file)
--- 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 +21,55 @@ static struct feature feature_list[] = {
                "large_bucket"},
        {0, 0, 0 },
 };
+
+#define compose_feature_string(type)                           \
+({                                                                     \
+       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,  \
+                                               "[");   \
+                       } else {                                        \
+                               out += snprintf(out, buf + size - out,  \
+                                               " [");                  \
+                       }                                               \
+               } else if (!first) {                                    \
+                       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_compat(struct cache_set *c, char *buf, int size)
+{
+       char *out = buf;
+       compose_feature_string(COMPAT);
+       return out - buf;
+}
+
+int bch_print_cache_set_feature_ro_compat(struct cache_set *c, char *buf, int size)
+{
+       char *out = buf;
+       compose_feature_string(RO_COMPAT);
+       return out - buf;
+}
+
+int bch_print_cache_set_feature_incompat(struct cache_set *c, char *buf, int size)
+{
+       char *out = buf;
+       compose_feature_string(INCOMPAT);
+       return out - buf;
+}

diff --git a/drivers/md/bcache/features.h b/drivers/md/bcache/features.h
index dca052c..a1653c4 100644 (file)
--- a/drivers/md/bcache/features.h
+++ b/drivers/md/bcache/features.h
@@ -78,4 +78,9 @@ 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_compat(struct cache_set *c, char *buf, int size);
+int bch_print_cache_set_feature_ro_compat(struct cache_set *c, char *buf, int size);
+int bch_print_cache_set_feature_incompat(struct cache_set *c, char *buf, int size);
+
 #endif

diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
index 0dadec5..ac06c0b 100644 (file)
--- 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 +89,9 @@ read_attribute(btree_used_percent);
 read_attribute(average_key_size);
 read_attribute(dirty_data);
 read_attribute(bset_tree_stats);
+read_attribute(feature_compat);
+read_attribute(feature_ro_compat);
+read_attribute(feature_incompat);
 
 read_attribute(state);
 read_attribute(cache_read_races);
@@ -779,6 +783,13 @@ SHOW(__bch_cache_set)
        if (attr == &sysfs_bset_tree_stats)
                return bch_bset_print_stats(c, buf);
 
+       if (attr == &sysfs_feature_compat)
+               return bch_print_cache_set_feature_compat(c, buf, PAGE_SIZE);
+       if (attr == &sysfs_feature_ro_compat)
+               return bch_print_cache_set_feature_ro_compat(c, buf, PAGE_SIZE);
+       if (attr == &sysfs_feature_incompat)
+               return bch_print_cache_set_feature_incompat(c, buf, PAGE_SIZE);
+
        return 0;
 }
 SHOW_LOCKED(bch_cache_set)
@@ -987,6 +998,9 @@ static struct attribute *bch_cache_set_internal_files[] = {
        &sysfs_io_disable,
        &sysfs_cutoff_writeback,
        &sysfs_cutoff_writeback_sync,
+       &sysfs_feature_compat,
+       &sysfs_feature_ro_compat,
+       &sysfs_feature_incompat,
        NULL
 };
 KTYPE(bch_cache_set_internal);