btrfs: sysfs: export supported send stream version

This reports the latest send stream version supported by the kernel as
the feature in /sys/fs/btrfs/features/send_stream_version .

Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index c71db7acb89d053b43622fd2a2a4001d7b2c36bf..13354de562013a5e04d80c0e3a5234c2abe32efb 100644 (file)
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -14,6 +14,7 @@
 #include "ctree.h"
 #include "discard.h"
 #include "disk-io.h"
+#include "send.h"
 #include "transaction.h"
 #include "sysfs.h"
 #include "volumes.h"
@@ -321,9 +322,17 @@ static ssize_t supported_checksums_show(struct kobject *kobj,
 }
 BTRFS_ATTR(static_feature, supported_checksums, supported_checksums_show);
 
+static ssize_t send_stream_version_show(struct kobject *kobj,
+                                       struct kobj_attribute *ka, char *buf)
+{
+       return snprintf(buf, PAGE_SIZE, "%d\n", BTRFS_SEND_STREAM_VERSION);
+}
+BTRFS_ATTR(static_feature, send_stream_version, send_stream_version_show);
+
 static struct attribute *btrfs_supported_static_feature_attrs[] = {
        BTRFS_ATTR_PTR(static_feature, rmdir_subvol),
        BTRFS_ATTR_PTR(static_feature, supported_checksums),
+       BTRFS_ATTR_PTR(static_feature, send_stream_version),
        NULL
 };