f2fs: add compress_mode mount option

We will add a new "compress_mode" mount option to control file
compression mode. This supports "fs" and "user". In "fs" mode (default),
f2fs does automatic compression on the compression enabled files.
In "user" mode, f2fs disables the automaic compression and gives the
user discretion of choosing the target file and the timing. It means
the user can do manual compression/decompression on the compression
enabled files using ioctls.
Signed-off-by: Daeho Jeong <daehojeong@google.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Documentation/filesystems/f2fs.rst

@@ -261,6 +261,13 @@ compress_extension=%s	 Support adding specified extension, so that f2fs can enab
 			 Note that, there is one reserved special extension '*', it
 			 can be set to enable compression for all files.
 compress_chksum		 Support verifying chksum of raw data in compressed cluster.
+compress_mode=%s	 Control file compression mode. This supports "fs" and "user"
+			 modes. In "fs" mode (default), f2fs does automatic compression
+			 on the compression enabled files. In "user" mode, f2fs disables
+			 the automaic compression and gives the user discretion of
+			 choosing the target file and the timing. The user can do manual
+			 compression/decompression on the compression enabled files using
+			 ioctls.
 inlinecrypt		 When possible, encrypt/decrypt the contents of encrypted
 			 files using the blk-crypto framework rather than
 			 filesystem-layer encryption. This allows the use of
@@ -811,6 +818,34 @@ Compress metadata layout::
 	| data length | data chksum | reserved |      compressed data       |
 	+-------------+-------------+----------+----------------------------+
 
+Compression mode
+--------------------------
+
+f2fs supports "fs" and "user" compression modes with "compression_mode" mount option.
+With this option, f2fs provides a choice to select the way how to compress the
+compression enabled files (refer to "Compression implementation" section for how to
+enable compression on a regular inode).
+
+1) compress_mode=fs
+This is the default option. f2fs does automatic compression in the writeback of the
+compression enabled files.
+
+2) compress_mode=user
+This disables the automaic compression and gives the user discretion of choosing the
+target file and the timing. The user can do manual compression/decompression on the
+compression enabled files using F2FS_IOC_DECOMPRESS_FILE and F2FS_IOC_COMPRESS_FILE
+ioctls like the below.
+
+To decompress a file,
+
+fd = open(filename, O_WRONLY, 0);
+ret = ioctl(fd, F2FS_IOC_DECOMPRESS_FILE);
+
+To compress a file,
+
+fd = open(filename, O_WRONLY, 0);
+ret = ioctl(fd, F2FS_IOC_COMPRESS_FILE);
+
 NVMe Zoned Namespace devices
 ----------------------------
 

fs/f2fs/compress.c

@@ -944,7 +944,7 @@ int f2fs_is_compressed_cluster(struct inode *inode, pgoff_t index)
 
 static bool cluster_may_compress(struct compress_ctx *cc)
 {
-	if (!f2fs_compressed_file(cc->inode))
+	if (!f2fs_need_compress_data(cc->inode))
 		return false;
 	if (f2fs_is_atomic_file(cc->inode))
 		return false;

fs/f2fs/data.c

@@ -3147,7 +3147,7 @@ static inline bool __should_serialize_io(struct inode *inode,
 	if (IS_NOQUOTA(inode))
 		return false;
 
-	if (f2fs_compressed_file(inode))
+	if (f2fs_need_compress_data(inode))
 		return true;
 	if (wbc->sync_mode != WB_SYNC_ALL)
 		return true;

fs/f2fs/f2fs.h

@@ -148,6 +148,7 @@ struct f2fs_mount_info {
 	unsigned char compress_log_size;	/* cluster log size */
 	bool compress_chksum;			/* compressed data chksum */
 	unsigned char compress_ext_cnt;		/* extension count */
+	int compress_mode;			/* compression mode */
 	unsigned char extensions[COMPRESS_EXT_NUM][F2FS_EXTENSION_LEN];	/* extensions */
 };
 
@@ -677,6 +678,7 @@ enum {
 	FI_COMPRESSED_FILE,	/* indicate file's data can be compressed */
 	FI_COMPRESS_CORRUPT,	/* indicate compressed cluster is corrupted */
 	FI_MMAP_FILE,		/* indicate file was mmapped */
+	FI_ENABLE_COMPRESS,	/* enable compression in "user" compression mode */
 	FI_MAX,			/* max flag, never be used */
 };
 
@@ -1244,6 +1246,18 @@ enum fsync_mode {
 	FSYNC_MODE_NOBARRIER,	/* fsync behaves nobarrier based on posix */
 };
 
+enum {
+	COMPR_MODE_FS,		/*
+				 * automatically compress compression
+				 * enabled files
+				 */
+	COMPR_MODE_USER,	/*
+				 * automatical compression is disabled.
+				 * user can control the file compression
+				 * using ioctls
+				 */
+};
+
 /*
  * this value is set in page as a private data which indicate that
  * the page is atomically written, and it is in inmem_pages list.
@@ -2759,6 +2773,22 @@ static inline int f2fs_compressed_file(struct inode *inode)
 		is_inode_flag_set(inode, FI_COMPRESSED_FILE);
 }
 
+static inline bool f2fs_need_compress_data(struct inode *inode)
+{
+	int compress_mode = F2FS_OPTION(F2FS_I_SB(inode)).compress_mode;
+
+	if (!f2fs_compressed_file(inode))
+		return false;
+
+	if (compress_mode == COMPR_MODE_FS)
+		return true;
+	else if (compress_mode == COMPR_MODE_USER &&
+			is_inode_flag_set(inode, FI_ENABLE_COMPRESS))
+		return true;
+
+	return false;
+}
+
 static inline unsigned int addrs_per_inode(struct inode *inode)
 {
 	unsigned int addrs = CUR_ADDRS_PER_INODE(inode) -

fs/f2fs/segment.c

@@ -3261,7 +3261,7 @@ static int __get_segment_type_6(struct f2fs_io_info *fio)
 			else
 				return CURSEG_COLD_DATA;
 		}
-		if (file_is_cold(inode) || f2fs_compressed_file(inode))
+		if (file_is_cold(inode) || f2fs_need_compress_data(inode))
 			return CURSEG_COLD_DATA;
 		if (file_is_hot(inode) ||
 				is_inode_flag_set(inode, FI_HOT_DATA) ||

fs/f2fs/super.c

@@ -147,6 +147,7 @@ enum {
 	Opt_compress_log_size,
 	Opt_compress_extension,
 	Opt_compress_chksum,
+	Opt_compress_mode,
 	Opt_atgc,
 	Opt_err,
 };
@@ -216,6 +217,7 @@ static match_table_t f2fs_tokens = {
 	{Opt_compress_log_size, "compress_log_size=%u"},
 	{Opt_compress_extension, "compress_extension=%s"},
 	{Opt_compress_chksum, "compress_chksum"},
+	{Opt_compress_mode, "compress_mode=%s"},
 	{Opt_atgc, "atgc"},
 	{Opt_err, NULL},
 };
@@ -939,11 +941,26 @@ static int parse_options(struct super_block *sb, char *options, bool is_remount)
 		case Opt_compress_chksum:
 			F2FS_OPTION(sbi).compress_chksum = true;
 			break;
+		case Opt_compress_mode:
+			name = match_strdup(&args[0]);
+			if (!name)
+				return -ENOMEM;
+			if (!strcmp(name, "fs")) {
+				F2FS_OPTION(sbi).compress_mode = COMPR_MODE_FS;
+			} else if (!strcmp(name, "user")) {
+				F2FS_OPTION(sbi).compress_mode = COMPR_MODE_USER;
+			} else {
+				kfree(name);
+				return -EINVAL;
+			}
+			kfree(name);
+			break;
 #else
 		case Opt_compress_algorithm:
 		case Opt_compress_log_size:
 		case Opt_compress_extension:
 		case Opt_compress_chksum:
+		case Opt_compress_mode:
 			f2fs_info(sbi, "compression options not supported");
 			break;
 #endif
@@ -1532,6 +1549,11 @@ static inline void f2fs_show_compress_options(struct seq_file *seq,
 
 	if (F2FS_OPTION(sbi).compress_chksum)
 		seq_puts(seq, ",compress_chksum");
+
+	if (F2FS_OPTION(sbi).compress_mode == COMPR_MODE_FS)
+		seq_printf(seq, ",compress_mode=%s", "fs");
+	else if (F2FS_OPTION(sbi).compress_mode == COMPR_MODE_USER)
+		seq_printf(seq, ",compress_mode=%s", "user");
 }
 
 static int f2fs_show_options(struct seq_file *seq, struct dentry *root)
@@ -1681,6 +1703,7 @@ static void default_options(struct f2fs_sb_info *sbi)
 	F2FS_OPTION(sbi).compress_algorithm = COMPRESS_LZ4;
 	F2FS_OPTION(sbi).compress_log_size = MIN_COMPRESS_LOG_SIZE;
 	F2FS_OPTION(sbi).compress_ext_cnt = 0;
+	F2FS_OPTION(sbi).compress_mode = COMPR_MODE_FS;
 	F2FS_OPTION(sbi).bggc_mode = BGGC_MODE_ON;
 
 	sbi->sb->s_flags &= ~SB_INLINECRYPT;