f2fs: expose extension_list sysfs entry

This patch adds a sysfs entry 'extension_list' to support
query/add/del item in extension list.

Query:
cat /sys/fs/f2fs/<device>/extension_list

Add:
echo 'extension' > /sys/fs/f2fs/<device>/extension_list

Del:
echo '!extension' > /sys/fs/f2fs/<device>/extension_list
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Documentation/ABI/testing/sysfs-fs-f2fs

@@ -192,3 +192,12 @@ Date:		November 2017
 Contact:	"Sheng Yong" <shengyong1@huawei.com>
 Description:
 		 Controls readahead inode block in readdir.
+
+What:		/sys/fs/f2fs/<disk>/extension_list
+Date:		Feburary 2018
+Contact:	"Chao Yu" <yuchao0@huawei.com>
+Description:
+		 Used to control configure extension list:
+		 - Query: cat /sys/fs/f2fs/<disk>/extension_list
+		 - Add: echo 'extension' > /sys/fs/f2fs/<disk>/extension_list
+		 - Del: echo '!extension' > /sys/fs/f2fs/<disk>/extension_list

fs/f2fs/f2fs.h

@@ -1047,7 +1047,7 @@ struct f2fs_sb_info {
 	struct super_block *sb;			/* pointer to VFS super block */
 	struct proc_dir_entry *s_proc;		/* proc entry */
 	struct f2fs_super_block *raw_super;	/* raw super block pointer */
-	struct mutex sb_lock;			/* lock for raw super block */
+	struct rw_semaphore sb_lock;		/* lock for raw super block */
 	int valid_super_block;			/* valid super block no */
 	unsigned long s_flag;				/* flags for sbi */
 
@@ -2605,6 +2605,8 @@ void handle_failed_inode(struct inode *inode);
 /*
  * namei.c
  */
+int update_extension_list(struct f2fs_sb_info *sbi, const char *name,
+								bool set);
 struct dentry *f2fs_get_parent(struct dentry *child);
 
 /*

fs/f2fs/file.c

@@ -1970,7 +1970,7 @@ static int f2fs_ioc_get_encryption_pwsalt(struct file *filp, unsigned long arg)
 	if (err)
 		return err;
 
-	mutex_lock(&sbi->sb_lock);
+	down_write(&sbi->sb_lock);
 
 	if (uuid_is_nonzero(sbi->raw_super->encrypt_pw_salt))
 		goto got_it;
@@ -1989,7 +1989,7 @@ static int f2fs_ioc_get_encryption_pwsalt(struct file *filp, unsigned long arg)
 									16))
 		err = -EFAULT;
 out_err:
-	mutex_unlock(&sbi->sb_lock);
+	up_write(&sbi->sb_lock);
 	mnt_drop_write_file(filp);
 	return err;
 }

fs/f2fs/namei.c

@@ -171,16 +171,52 @@ static int is_multimedia_file(const unsigned char *s, const char *sub)
 static inline void set_cold_files(struct f2fs_sb_info *sbi, struct inode *inode,
 		const unsigned char *name)
 {
-	int i;
-	__u8 (*extlist)[8] = sbi->raw_super->extension_list;
+	__u8 (*extlist)[F2FS_EXTENSION_LEN] = sbi->raw_super->extension_list;
+	int i, count;
+
+	down_read(&sbi->sb_lock);
+
+	count = le32_to_cpu(sbi->raw_super->extension_count);
 
-	int count = le32_to_cpu(sbi->raw_super->extension_count);
 	for (i = 0; i < count; i++) {
 		if (is_multimedia_file(name, extlist[i])) {
 			file_set_cold(inode);
 			break;
 		}
 	}
+
+	up_read(&sbi->sb_lock);
+}
+
+int update_extension_list(struct f2fs_sb_info *sbi, const char *name, bool set)
+{
+	__u8 (*extlist)[F2FS_EXTENSION_LEN] = sbi->raw_super->extension_list;
+	int count = le32_to_cpu(sbi->raw_super->extension_count);
+	int i;
+
+	for (i = 0; i < count; i++) {
+		if (strcmp(name, extlist[i]))
+			continue;
+
+		if (set)
+			return -EINVAL;
+
+		memcpy(extlist[i], extlist[i + 1],
+				F2FS_EXTENSION_LEN * (count - i - 1));
+		memset(extlist[count - 1], 0, F2FS_EXTENSION_LEN);
+		sbi->raw_super->extension_count = cpu_to_le32(count - 1);
+		return 0;
+	}
+
+	if (!set)
+		return -EINVAL;
+
+	if (count == F2FS_MAX_EXTENSION)
+		return -EINVAL;
+
+	strncpy(extlist[count], name, strlen(name));
+	sbi->raw_super->extension_count = cpu_to_le32(count + 1);
+	return 0;
 }
 
 static int f2fs_create(struct inode *dir, struct dentry *dentry, umode_t mode,

fs/f2fs/super.c

@@ -2222,7 +2222,7 @@ static void init_sb_info(struct f2fs_sb_info *sbi)
 	sbi->dirty_device = 0;
 	spin_lock_init(&sbi->dev_lock);
 
-	mutex_init(&sbi->sb_lock);
+	init_rwsem(&sbi->sb_lock);
 }
 
 static int init_percpu_info(struct f2fs_sb_info *sbi)

fs/f2fs/sysfs.c

@@ -136,6 +136,18 @@ static ssize_t f2fs_sbi_show(struct f2fs_attr *a,
 	if (!ptr)
 		return -EINVAL;
 
+	if (!strcmp(a->attr.name, "extension_list")) {
+		__u8 (*extlist)[F2FS_EXTENSION_LEN] =
+					sbi->raw_super->extension_list;
+		int count = le32_to_cpu(sbi->raw_super->extension_count);
+		int len = 0, i;
+
+		for (i = 0; i < count; i++)
+			len += snprintf(buf + len, PAGE_SIZE - len, "%s\n",
+								extlist[i]);
+		return len;
+	}
+
 	ui = (unsigned int *)(ptr + a->offset);
 
 	return snprintf(buf, PAGE_SIZE, "%u\n", *ui);
@@ -154,6 +166,32 @@ static ssize_t f2fs_sbi_store(struct f2fs_attr *a,
 	if (!ptr)
 		return -EINVAL;
 
+	if (!strcmp(a->attr.name, "extension_list")) {
+		const char *name = strim((char *)buf);
+		bool set = true;
+
+		if (name[0] == '!') {
+			name++;
+			set = false;
+		}
+
+		if (strlen(name) >= F2FS_EXTENSION_LEN)
+			return -EINVAL;
+
+		down_write(&sbi->sb_lock);
+
+		ret = update_extension_list(sbi, name, set);
+		if (ret)
+			goto out;
+
+		ret = f2fs_commit_super(sbi, false);
+		if (ret)
+			update_extension_list(sbi, name, !set);
+out:
+		up_write(&sbi->sb_lock);
+		return ret ? ret : count;
+	}
+
 	ui = (unsigned int *)(ptr + a->offset);
 
 	ret = kstrtoul(skip_spaces(buf), 0, &t);
@@ -307,6 +345,7 @@ F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, idle_interval, interval_time[REQ_TIME]);
 F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, iostat_enable, iostat_enable);
 F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, readdir_ra, readdir_ra);
 F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, gc_pin_file_thresh, gc_pin_file_threshold);
+F2FS_RW_ATTR(F2FS_SBI, f2fs_super_block, extension_list, extension_list);
 #ifdef CONFIG_F2FS_FAULT_INJECTION
 F2FS_RW_ATTR(FAULT_INFO_RATE, f2fs_fault_info, inject_rate, inject_rate);
 F2FS_RW_ATTR(FAULT_INFO_TYPE, f2fs_fault_info, inject_type, inject_type);
@@ -357,6 +396,7 @@ static struct attribute *f2fs_attrs[] = {
 	ATTR_LIST(iostat_enable),
 	ATTR_LIST(readdir_ra),
 	ATTR_LIST(gc_pin_file_thresh),
+	ATTR_LIST(extension_list),
 #ifdef CONFIG_F2FS_FAULT_INJECTION
 	ATTR_LIST(inject_rate),
 	ATTR_LIST(inject_type),

include/linux/f2fs_fs.h

@@ -21,6 +21,7 @@
 #define F2FS_BLKSIZE			4096	/* support only 4KB block */
 #define F2FS_BLKSIZE_BITS		12	/* bits for F2FS_BLKSIZE */
 #define F2FS_MAX_EXTENSION		64	/* # of extension entries */
+#define F2FS_EXTENSION_LEN		8	/* max size of extension */
 #define F2FS_BLK_ALIGN(x)	(((x) + F2FS_BLKSIZE - 1) >> F2FS_BLKSIZE_BITS)
 
 #define NULL_ADDR		((block_t)0)	/* used as block_t addresses */
@@ -101,7 +102,7 @@ struct f2fs_super_block {
 	__u8 uuid[16];			/* 128-bit uuid for volume */
 	__le16 volume_name[MAX_VOLUME_NAME];	/* volume name */
 	__le32 extension_count;		/* # of extensions below */
-	__u8 extension_list[F2FS_MAX_EXTENSION][8];	/* extension array */
+	__u8 extension_list[F2FS_MAX_EXTENSION][F2FS_EXTENSION_LEN];/* extension array */
 	__le32 cp_payload;
 	__u8 version[VERSION_LEN];	/* the kernel version */
 	__u8 init_version[VERSION_LEN];	/* the initial kernel version */