f2fs: support hot file extension

This patch supports to recognize hot file extension in f2fs, so that we
can allocate proper hot segment location for its data, which can lead to
better hot/cold seperation in filesystem.

In addition, we changes a bit on query/add/del operation method for
extension_list sysfs entry as below:

- 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
- Add: echo '[h/c]extension' > /sys/fs/f2fs/<disk>/extension_list
- Del: echo '[h/c]!extension' > /sys/fs/f2fs/<disk>/extension_list
- [h] means add/del hot file extension
- [c] means add/del cold file extension

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 59 insertions, 20 deletions

diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
index 2bd6e9f5746a..78ea0156f027 100644
--- a/fs/f2fs/namei.c
+++ b/fs/f2fs/namei.c
@@ -142,7 +142,7 @@ fail_drop:
 	return ERR_PTR(err);
 }
 
-static int is_multimedia_file(const unsigned char *s, const char *sub)
+static int is_extension_exist(const unsigned char *s, const char *sub)
 {
 	size_t slen = strlen(s);
 	size_t sublen = strlen(sub);
@@ -168,33 +168,59 @@ static int is_multimedia_file(const unsigned char *s, const char *sub)
 /*
  * Set multimedia files as cold files for hot/cold data separation
  */
-static inline void set_cold_files(struct f2fs_sb_info *sbi, struct inode *inode,
+static inline void set_file_temperature(struct f2fs_sb_info *sbi, struct inode *inode,
 		const unsigned char *name)
 {
 	__u8 (*extlist)[F2FS_EXTENSION_LEN] = sbi->raw_super->extension_list;
-	int i, count;
+	int i, cold_count, hot_count;
 
 	down_read(&sbi->sb_lock);
 
-	count = le32_to_cpu(sbi->raw_super->extension_count);
+	cold_count = le32_to_cpu(sbi->raw_super->extension_count);
+	hot_count = sbi->raw_super->hot_ext_count;
 
-	for (i = 0; i < count; i++) {
-		if (is_multimedia_file(name, extlist[i])) {
+	for (i = 0; i < cold_count + hot_count; i++) {
+		if (!is_extension_exist(name, extlist[i]))
+			continue;
+		if (i < cold_count)
 			file_set_cold(inode);
-			break;
-		}
+		else
+			file_set_hot(inode);
+		break;
 	}
 
 	up_read(&sbi->sb_lock);
 }
 
-int update_extension_list(struct f2fs_sb_info *sbi, const char *name, bool set)
+int update_extension_list(struct f2fs_sb_info *sbi, const char *name,
+							bool hot, bool set)
 {
 	__u8 (*extlist)[F2FS_EXTENSION_LEN] = sbi->raw_super->extension_list;
-	int count = le32_to_cpu(sbi->raw_super->extension_count);
+	int cold_count = le32_to_cpu(sbi->raw_super->extension_count);
+	int hot_count = sbi->raw_super->hot_ext_count;
+	int total_count = cold_count + hot_count;
+	int start, count;
 	int i;
 
-	for (i = 0; i < count; i++) {
+	if (set) {
+		if (total_count == F2FS_MAX_EXTENSION)
+			return -EINVAL;
+	} else {
+		if (!hot && !cold_count)
+			return -EINVAL;
+		if (hot && !hot_count)
+			return -EINVAL;
+	}
+
+	if (hot) {
+		start = cold_count;
+		count = total_count;
+	} else {
+		start = 0;
+		count = cold_count;
+	}
+
+	for (i = start; i < count; i++) {
 		if (strcmp(name, extlist[i]))
 			continue;
 
@@ -202,20 +228,33 @@ int update_extension_list(struct f2fs_sb_info *sbi, const char *name, bool 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);
+				F2FS_EXTENSION_LEN * (total_count - i - 1));
+		memset(extlist[total_count - 1], 0, F2FS_EXTENSION_LEN);
+		if (hot)
+			sbi->raw_super->hot_ext_count = hot_count - 1;
+		else
+			sbi->raw_super->extension_count =
+						cpu_to_le32(cold_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);
+	if (hot) {
+		strncpy(extlist[count], name, strlen(name));
+		sbi->raw_super->hot_ext_count = hot_count + 1;
+	} else {
+		char buf[F2FS_MAX_EXTENSION][F2FS_EXTENSION_LEN];
+
+		memcpy(buf, &extlist[cold_count],
+				F2FS_EXTENSION_LEN * hot_count);
+		memset(extlist[cold_count], 0, F2FS_EXTENSION_LEN);
+		strncpy(extlist[cold_count], name, strlen(name));
+		memcpy(&extlist[cold_count + 1], buf,
+				F2FS_EXTENSION_LEN * hot_count);
+		sbi->raw_super->extension_count = cpu_to_le32(cold_count + 1);
+	}
 	return 0;
 }
 
@@ -239,7 +278,7 @@ static int f2fs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 		return PTR_ERR(inode);
 
 	if (!test_opt(sbi, DISABLE_EXT_IDENTIFY))
-		set_cold_files(sbi, inode, dentry->d_name.name);
+		set_file_temperature(sbi, inode, dentry->d_name.name);
 
 	inode->i_op = &f2fs_file_inode_operations;
 	inode->i_fop = &f2fs_file_operations;