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From:   Daeho Jeong <daeho43@gmail.com>
To:     linux-kernel@vger.kernel.org,
        linux-f2fs-devel@lists.sourceforge.net, kernel-team@android.com
Cc:     Daeho Jeong <daehojeong@google.com>
Subject: [PATCH v6 1/2] f2fs: add F2FS_IOC_GET_COMPRESS_OPTION ioctl
Date:   Fri, 30 Oct 2020 11:27:47 +0900
Message-Id: <20201030022748.332831-1-daeho43@gmail.com>
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From: Daeho Jeong <daehojeong@google.com>

Added a new F2FS_IOC_GET_COMPRESS_OPTION ioctl to get file compression
option of a file.

struct f2fs_comp_option {
    u8 algorithm;         => compression algorithm
                          => 0:lzo, 1:lz4, 2:zstd, 3:lzorle
    u8 log_cluster_size;  => log scale cluster size
                          => 2 ~ 8
};

struct f2fs_comp_option option;

ioctl(fd, F2FS_IOC_GET_COMPRESS_OPTION, &option);

Signed-off-by: Daeho Jeong <daehojeong@google.com>
---

v4: changed commit message.
v3: changed the error number more specific.
v2: added ioctl description.
---
 fs/f2fs/f2fs.h |  7 +++++++
 fs/f2fs/file.c | 30 ++++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 53fe2853579c..a33c90cf979b 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -433,6 +433,8 @@ static inline bool __has_cursum_space(struct f2fs_journal *journal,
 					_IOR(F2FS_IOCTL_MAGIC, 19, __u64)
 #define F2FS_IOC_SEC_TRIM_FILE		_IOW(F2FS_IOCTL_MAGIC, 20,	\
 						struct f2fs_sectrim_range)
+#define F2FS_IOC_GET_COMPRESS_OPTION	_IOR(F2FS_IOCTL_MAGIC, 21,	\
+						struct f2fs_comp_option)
 
 /*
  * should be same as XFS_IOC_GOINGDOWN.
@@ -481,6 +483,11 @@ struct f2fs_sectrim_range {
 	u64 flags;
 };
 
+struct f2fs_comp_option {
+	u8 algorithm;
+	u8 log_cluster_size;
+};
+
 /* for inline stuff */
 #define DEF_INLINE_RESERVED_SIZE	1
 static inline int get_extra_isize(struct inode *inode);
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index ef5a844de53f..8922ab191a9d 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -3936,6 +3936,33 @@ static int f2fs_sec_trim_file(struct file *filp, unsigned long arg)
 	return ret;
 }
 
+static int f2fs_ioc_get_compress_option(struct file *filp, unsigned long arg)
+{
+	struct inode *inode = file_inode(filp);
+	struct f2fs_comp_option option;
+
+	if (!f2fs_sb_has_compression(F2FS_I_SB(inode)))
+		return -EOPNOTSUPP;
+
+	inode_lock(inode);
+
+	if (!f2fs_compressed_file(inode)) {
+		inode_unlock(inode);
+		return -ENODATA;
+	}
+
+	option.algorithm = F2FS_I(inode)->i_compress_algorithm;
+	option.log_cluster_size = F2FS_I(inode)->i_log_cluster_size;
+
+	inode_unlock(inode);
+
+	if (copy_to_user((struct f2fs_comp_option __user *)arg, &option,
+				sizeof(option)))
+		return -EFAULT;
+
+	return 0;
+}
+
 long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
 	if (unlikely(f2fs_cp_error(F2FS_I_SB(file_inode(filp)))))
@@ -4024,6 +4051,8 @@ long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 		return f2fs_reserve_compress_blocks(filp, arg);
 	case F2FS_IOC_SEC_TRIM_FILE:
 		return f2fs_sec_trim_file(filp, arg);
+	case F2FS_IOC_GET_COMPRESS_OPTION:
+		return f2fs_ioc_get_compress_option(filp, arg);
 	default:
 		return -ENOTTY;
 	}
@@ -4194,6 +4223,7 @@ long f2fs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	case F2FS_IOC_RELEASE_COMPRESS_BLOCKS:
 	case F2FS_IOC_RESERVE_COMPRESS_BLOCKS:
 	case F2FS_IOC_SEC_TRIM_FILE:
+	case F2FS_IOC_GET_COMPRESS_OPTION:
 		break;
 	default:
 		return -ENOIOCTLCMD;
-- 
2.29.1.341.ge80a0c044ae-goog