With the compat and compat-ro bits, it's possible for file systems to
exist that have features that aren't supported by the kernel's file system
implementation yet still be mountable.
This patch publishes read-only info on those features using a prefix:number
format, where the number is the bit number rather than the shifted value.
e.g. "compat:12"
Signed-off-by: Jeff Mahoney <jeffm@xxxxxxxx>
---
fs/btrfs/sysfs.c | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 71 insertions(+), 4 deletions(-)
--- a/fs/btrfs/sysfs.c 2013-09-10 15:58:32.209384497 -0400
+++ b/fs/btrfs/sysfs.c 2013-09-10 15:58:32.645377839 -0400
@@ -68,6 +68,58 @@ static struct kobj_type btrfs_supp_feat_
.release = kobj_completion_release,
};
+const char * const btrfs_feature_set_names[FEAT_MAX] = {
+ [FEAT_COMPAT] = "compat",
+ [FEAT_COMPAT_RO] = "compat_ro",
+ [FEAT_INCOMPAT] = "incompat",
+};
+
+static char btrfs_feature_names[FEAT_MAX][64][13];
+static struct btrfs_feature_attr btrfs_feature_attrs[FEAT_MAX][64];
+
+static void init_feature_set_attrs(enum btrfs_feature_set set)
+{
+ int i;
+ int len = strlen(btrfs_feature_set_names[set]) + 4;
+
+ for (i = 0; i < 64; i++) {
+ char *name = btrfs_feature_names[set][i];
+ struct btrfs_feature_attr *fa;
+
+ snprintf(name, len, "%s:%u", btrfs_feature_set_names[set], i);
+
+ fa = &btrfs_feature_attrs[set][i];
+ fa->attr.name = name;
+ fa->attr.mode = S_IRUGO;
+ fa->feature_set = set;
+ fa->feature_bit = (1ULL << i);
+ }
+}
+
+static void init_feature_attrs(void)
+{
+ int i;
+
+ init_feature_set_attrs(FEAT_COMPAT);
+ init_feature_set_attrs(FEAT_COMPAT_RO);
+ init_feature_set_attrs(FEAT_INCOMPAT);
+
+ /* Copy the names over for supported features */
+ for (i = 0; btrfs_supp_feature_attrs[i]; i++) {
+ struct btrfs_feature_attr *fa;
+ struct attribute *attr;
+ int n;
+
+ fa = to_btrfs_feature_attr(btrfs_supp_feature_attrs[i]);
+ n = ilog2(fa->feature_bit);
+
+ attr = &btrfs_feature_attrs[fa->feature_set][n].attr;
+ attr->name = fa->attr.name;
+
+ btrfs_feature_names[fa->feature_set][n][0] = '\0';
+ }
+}
+
static u64 get_features(struct btrfs_fs_info *fs_info,
enum btrfs_feature_set set)
{
@@ -138,12 +190,12 @@ static struct kobj_type btrfs_ktype = {
.release = kobj_completion_release,
};
-static int add_per_fs_features(struct btrfs_fs_info *fs_info)
+static int add_per_fs_feature_set(struct btrfs_fs_info *fs_info,
+ enum btrfs_feature_set set)
{
int i;
- for (i = 0; btrfs_supp_feature_attrs[i]; i++) {
- struct attribute *attr = btrfs_supp_feature_attrs[i];
- struct btrfs_feature_attr *fa = to_btrfs_feature_attr(attr);
+ for (i = 0; i < ARRAY_SIZE(btrfs_feature_attrs[0]); i++) {
+ struct btrfs_feature_attr *fa = &btrfs_feature_attrs[set][i];
u64 features = get_features(fs_info, fa->feature_set);
int error;
@@ -158,6 +210,20 @@ static int add_per_fs_features(struct bt
return 0;
}
+static int add_per_fs_features(struct btrfs_fs_info *fs_info)
+{
+ enum btrfs_feature_set set;
+ int error;
+
+ for (set = FEAT_COMPAT; set < FEAT_MAX; set++) {
+ error = add_per_fs_feature_set(fs_info, set);
+ if (error)
+ return error;
+ }
+
+ return 0;
+}
+
/* /sys/fs/btrfs/ entry */
static struct kset *btrfs_kset;
@@ -207,6 +273,7 @@ int btrfs_init_sysfs(void)
if (!btrfs_kset)
return -ENOMEM;
+ init_feature_attrs();
kobj_completion_init(&btrfs_features, &btrfs_supp_feat_ktype);
btrfs_features.kc_kobj.kset = btrfs_kset;
ret = kobject_add(&btrfs_features.kc_kobj, NULL, "features");
--
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