User-space should have the opportunity to check what features doest ext4
support in each particular copy. This adds easy interface by creating new
"features" directory in sys/fs/ext4/. In that directory files
advertising feature names can be created.
Add lazy_itable_init to the feature list.
Signed-off-by: Lukas Czerner <lczerner@xxxxxxxxxx>
---
fs/ext4/ext4.h | 5 +++++
fs/ext4/super.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 54 insertions(+), 1 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 96884c5..74ec1fc 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1572,6 +1572,11 @@ struct ext4_li_request {
unsigned long lr_next_sched;
};
+struct ext4_features {
+ struct kobject f_kobj;
+ struct completion f_kobj_unregister;
+};
+
/*
* Function prototypes
*/
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 2b53a48..bb84c27 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -57,6 +57,7 @@ struct proc_dir_entry *ext4_proc_root;
static struct kset *ext4_kset;
struct ext4_lazy_init *ext4_li_info;
struct mutex ext4_li_mtx;
+struct ext4_features *ext4_feat;
static int ext4_load_journal(struct super_block *, struct ext4_super_block *,
unsigned long journal_devnum);
@@ -2413,6 +2414,7 @@ static struct ext4_attr ext4_attr_##_name = { \
#define EXT4_ATTR(name, mode, show, store) \
static struct ext4_attr ext4_attr_##name = __ATTR(name, mode, show, store)
+#define EXT4_INFO_ATTR(name) EXT4_ATTR(name, 0444, NULL, NULL)
#define EXT4_RO_ATTR(name) EXT4_ATTR(name, 0444, name##_show, NULL)
#define EXT4_RW_ATTR(name) EXT4_ATTR(name, 0644, name##_show, name##_store)
#define EXT4_RW_ATTR_SBI_UI(name, elname) \
@@ -2449,6 +2451,14 @@ static struct attribute *ext4_attrs[] = {
NULL,
};
+/* Features this copy of ext4 supports */
+EXT4_INFO_ATTR(lazy_itable_init);
+
+static struct attribute *ext4_feat_attrs[] = {
+ ATTR_LIST(lazy_itable_init),
+ NULL,
+};
+
static ssize_t ext4_attr_show(struct kobject *kobj,
struct attribute *attr, char *buf)
{
@@ -2477,7 +2487,6 @@ static void ext4_sb_release(struct kobject *kobj)
complete(&sbi->s_kobj_unregister);
}
-
static const struct sysfs_ops ext4_attr_ops = {
.show = ext4_attr_show,
.store = ext4_attr_store,
@@ -2489,6 +2498,17 @@ static struct kobj_type ext4_ktype = {
.release = ext4_sb_release,
};
+static void ext4_feat_release(struct kobject *kobj)
+{
+ complete(&ext4_feat->f_kobj_unregister);
+}
+
+static struct kobj_type ext4_feat_ktype = {
+ .default_attrs = ext4_feat_attrs,
+ .sysfs_ops = &ext4_attr_ops,
+ .release = ext4_feat_release,
+};
+
/*
* Check whether this filesystem can be mounted based on
* the features present and the RDONLY/RDWR mount requested.
@@ -4716,6 +4736,30 @@ static struct file_system_type ext4_fs_type = {
.fs_flags = FS_REQUIRES_DEV,
};
+int __init ext4_init_feat_adverts(void)
+{
+ struct ext4_features *ef;
+ int ret = -ENOMEM;
+
+ ef = kzalloc(sizeof(struct ext4_features), GFP_KERNEL);
+ if (!ef)
+ goto out;
+
+ ef->f_kobj.kset = ext4_kset;
+ init_completion(&ef->f_kobj_unregister);
+ ret = kobject_init_and_add(&ef->f_kobj, &ext4_feat_ktype, NULL,
+ "features");
+ if (ret) {
+ kfree(ef);
+ goto out;
+ }
+
+ ext4_feat = ef;
+ ret = 0;
+out:
+ return ret;
+}
+
static int __init init_ext4_fs(void)
{
int err;
@@ -4728,6 +4772,9 @@ static int __init init_ext4_fs(void)
if (!ext4_kset)
goto out4;
ext4_proc_root = proc_mkdir("fs/ext4", NULL);
+
+ err = ext4_init_feat_adverts();
+
err = init_ext4_mballoc();
if (err)
goto out3;
@@ -4756,6 +4803,7 @@ out1:
out2:
exit_ext4_mballoc();
out3:
+ kfree(ext4_feat);
remove_proc_entry("fs/ext4", NULL);
kset_unregister(ext4_kset);
out4:
--
1.7.2.2
--
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