This patch exposes what features are supported by current f2fs build to sysfs
entry.

Signed-off-by: Jaegeuk Kim <jaeg...@kernel.org>
---
 fs/f2fs/f2fs.h  |   6 +++
 fs/f2fs/file.c  |   3 +-
 fs/f2fs/sysfs.c | 114 +++++++++++++++++++++++++++++++++++++++++++-------------
 3 files changed, 96 insertions(+), 27 deletions(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 1833eefe47b3..a336021b777f 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -2864,6 +2864,12 @@ static inline int f2fs_sb_has_project_quota(struct 
super_block *sb)
        return F2FS_HAS_FEATURE(sb, F2FS_FEATURE_PRJQUOTA);
 }
 
+static inline int f2fs_sb_support_atomic_write(void)
+{
+       /* Validated with sqlite */
+       return 1;
+}
+
 #ifdef CONFIG_BLK_DEV_ZONED
 static inline int get_blkz_type(struct f2fs_sb_info *sbi,
                        struct block_device *bdev, block_t blkaddr)
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index e4a45f02cd4e..0f4dbeb61845 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -2384,7 +2384,8 @@ static int f2fs_ioc_get_features(struct file *filp, 
unsigned long arg)
        u32 sb_feature = le32_to_cpu(F2FS_I_SB(inode)->raw_super->feature);
 
        /* Must validate to set it with SQLite behavior in Android. */
-       sb_feature |= F2FS_FEATURE_ATOMIC_WRITE;
+       if (f2fs_sb_support_atomic_write())
+               sb_feature |= F2FS_FEATURE_ATOMIC_WRITE;
 
        return put_user(sb_feature, (u32 __user *)arg);
 }
diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
index 71191d89917d..0bd57e8769c6 100644
--- a/fs/f2fs/sysfs.c
+++ b/fs/f2fs/sysfs.c
@@ -18,7 +18,6 @@
 #include "gc.h"
 
 static struct proc_dir_entry *f2fs_proc_root;
-static struct kset *f2fs_kset;
 
 /* Sysfs support for f2fs */
 enum {
@@ -41,6 +40,7 @@ struct f2fs_attr {
                         const char *, size_t);
        int struct_type;
        int offset;
+       int id;
 };
 
 static unsigned char *__struct_ptr(struct f2fs_sb_info *sbi, int struct_type)
@@ -155,6 +155,24 @@ static void f2fs_sb_release(struct kobject *kobj)
        complete(&sbi->s_kobj_unregister);
 }
 
+enum feat_id {
+       FEAT_CRYPTO = 0,
+       FEAT_BLKZONED,
+       FEAT_ATOMIC_WRITE,
+};
+
+static ssize_t f2fs_feature_show(struct f2fs_attr *a,
+               struct f2fs_sb_info *sbi, char *buf)
+{
+       switch (a->id) {
+       case FEAT_CRYPTO:
+       case FEAT_BLKZONED:
+       case FEAT_ATOMIC_WRITE:
+               return snprintf(buf, PAGE_SIZE, "supported\n");
+       }
+       return 0;
+}
+
 #define F2FS_ATTR_OFFSET(_struct_type, _name, _mode, _show, _store, _offset) \
 static struct f2fs_attr f2fs_attr_##_name = {                  \
        .attr = {.name = __stringify(_name), .mode = _mode },   \
@@ -172,6 +190,13 @@ static struct f2fs_attr f2fs_attr_##_name = {              
        \
 #define F2FS_GENERAL_RO_ATTR(name) \
 static struct f2fs_attr f2fs_attr_##name = __ATTR(name, 0444, name##_show, 
NULL)
 
+#define F2FS_FEATURE_RO_ATTR(_name, _id)                       \
+static struct f2fs_attr f2fs_attr_##_name = {                  \
+       .attr = {.name = __stringify(_name), .mode = 0444 },    \
+       .show   = f2fs_feature_show,                            \
+       .id     = _id,                                          \
+}
+
 F2FS_RW_ATTR(GC_THREAD, f2fs_gc_kthread, gc_min_sleep_time, min_sleep_time);
 F2FS_RW_ATTR(GC_THREAD, f2fs_gc_kthread, gc_max_sleep_time, max_sleep_time);
 F2FS_RW_ATTR(GC_THREAD, f2fs_gc_kthread, gc_no_gc_sleep_time, 
no_gc_sleep_time);
@@ -197,6 +222,14 @@ F2FS_RW_ATTR(FAULT_INFO_TYPE, f2fs_fault_info, 
inject_type, inject_type);
 #endif
 F2FS_GENERAL_RO_ATTR(lifetime_write_kbytes);
 
+#ifdef CONFIG_F2FS_FS_ENCRYPTION
+F2FS_FEATURE_RO_ATTR(encryption, FEAT_CRYPTO);
+#endif
+#ifdef CONFIG_BLK_DEV_ZONED
+F2FS_FEATURE_RO_ATTR(block_zoned, FEAT_BLKZONED);
+#endif
+F2FS_FEATURE_RO_ATTR(atomic_write, FEAT_ATOMIC_WRITE);
+
 #define ATTR_LIST(name) (&f2fs_attr_##name.attr)
 static struct attribute *f2fs_attrs[] = {
        ATTR_LIST(gc_min_sleep_time),
@@ -226,17 +259,45 @@ static struct attribute *f2fs_attrs[] = {
        NULL,
 };
 
+static struct attribute *f2fs_feat_attrs[] = {
+#ifdef CONFIG_F2FS_FS_ENCRYPTION
+       ATTR_LIST(encryption),
+#endif
+#ifdef CONFIG_BLK_DEV_ZONED
+       ATTR_LIST(block_zoned),
+#endif
+       ATTR_LIST(atomic_write),
+       NULL,
+};
+
 static const struct sysfs_ops f2fs_attr_ops = {
        .show   = f2fs_attr_show,
        .store  = f2fs_attr_store,
 };
 
-static struct kobj_type f2fs_ktype = {
+static struct kobj_type f2fs_sb_ktype = {
        .default_attrs  = f2fs_attrs,
        .sysfs_ops      = &f2fs_attr_ops,
        .release        = f2fs_sb_release,
 };
 
+static struct kobj_type f2fs_ktype = {
+       .sysfs_ops      = &f2fs_attr_ops,
+};
+
+static struct kset f2fs_kset = {
+       .kobj   = {.ktype = &f2fs_ktype},
+};
+
+static struct kobj_type f2fs_feat_ktype = {
+       .default_attrs  = f2fs_feat_attrs,
+       .sysfs_ops      = &f2fs_attr_ops,
+};
+
+static struct kobject f2fs_feat = {
+       .kset   = &f2fs_kset,
+};
+
 static int segment_info_seq_show(struct seq_file *seq, void *offset)
 {
        struct super_block *sb = seq->private;
@@ -306,18 +367,29 @@ F2FS_PROC_FILE_DEF(segment_bits);
 
 int __init f2fs_register_sysfs(void)
 {
-       f2fs_proc_root = proc_mkdir("fs/f2fs", NULL);
+       int ret;
 
-       f2fs_kset = kset_create_and_add("f2fs", NULL, fs_kobj);
-       if (!f2fs_kset)
-               return -ENOMEM;
-       return 0;
+       kobject_set_name(&f2fs_kset.kobj, "f2fs");
+       f2fs_kset.kobj.parent = fs_kobj;
+       ret = kset_register(&f2fs_kset);
+       if (ret)
+               return ret;
+
+       ret = kobject_init_and_add(&f2fs_feat, &f2fs_feat_ktype,
+                                  NULL, "features");
+       if (ret)
+               kset_unregister(&f2fs_kset);
+       else
+               f2fs_proc_root = proc_mkdir("fs/f2fs", NULL);
+       return ret;
 }
 
 void f2fs_unregister_sysfs(void)
 {
-       kset_unregister(f2fs_kset);
+       kobject_put(&f2fs_feat);
+       kset_unregister(&f2fs_kset);
        remove_proc_entry("fs/f2fs", NULL);
+       f2fs_proc_root = NULL;
 }
 
 int f2fs_init_sysfs(struct f2fs_sb_info *sbi)
@@ -325,6 +397,13 @@ int f2fs_init_sysfs(struct f2fs_sb_info *sbi)
        struct super_block *sb = sbi->sb;
        int err;
 
+       sbi->s_kobj.kset = &f2fs_kset;
+       init_completion(&sbi->s_kobj_unregister);
+       err = kobject_init_and_add(&sbi->s_kobj, &f2fs_sb_ktype, NULL,
+                               "%s", sb->s_id);
+       if (err)
+               return err;
+
        if (f2fs_proc_root)
                sbi->s_proc = proc_mkdir(sb->s_id, f2fs_proc_root);
 
@@ -334,32 +413,15 @@ int f2fs_init_sysfs(struct f2fs_sb_info *sbi)
                proc_create_data("segment_bits", S_IRUGO, sbi->s_proc,
                                 &f2fs_seq_segment_bits_fops, sb);
        }
-
-       sbi->s_kobj.kset = f2fs_kset;
-       init_completion(&sbi->s_kobj_unregister);
-       err = kobject_init_and_add(&sbi->s_kobj, &f2fs_ktype, NULL,
-                                                       "%s", sb->s_id);
-       if (err)
-               goto err_out;
        return 0;
-err_out:
-       if (sbi->s_proc) {
-               remove_proc_entry("segment_info", sbi->s_proc);
-               remove_proc_entry("segment_bits", sbi->s_proc);
-               remove_proc_entry(sb->s_id, f2fs_proc_root);
-       }
-       return err;
 }
 
 void f2fs_exit_sysfs(struct f2fs_sb_info *sbi)
 {
-       kobject_del(&sbi->s_kobj);
-       kobject_put(&sbi->s_kobj);
-       wait_for_completion(&sbi->s_kobj_unregister);
-
        if (sbi->s_proc) {
                remove_proc_entry("segment_info", sbi->s_proc);
                remove_proc_entry("segment_bits", sbi->s_proc);
                remove_proc_entry(sbi->sb->s_id, f2fs_proc_root);
        }
+       kobject_del(&sbi->s_kobj);
 }
-- 
2.13.0.rc1.294.g07d810a77f-goog

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