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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] f2fs: add F2FS_IOC_SEC_TRIM_FILE ioctl
Date:   Tue,  9 Jun 2020 15:01:37 +0900
Message-Id: <20200609060137.143501-1-daeho43@gmail.com>
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From: Daeho Jeong <daehojeong@google.com>

Added a new ioctl to send discard commands or/and zero out
to whole data area of a regular file for security reason.

Signed-off-by: Daeho Jeong <daehojeong@google.com>
---
 fs/f2fs/f2fs.h |   8 +++
 fs/f2fs/file.c | 149 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 157 insertions(+)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index c812fb8e2d9c..ca139fac5a73 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -434,6 +434,7 @@ static inline bool __has_cursum_space(struct f2fs_journal *journal,
 					_IOR(F2FS_IOCTL_MAGIC, 18, __u64)
 #define F2FS_IOC_RESERVE_COMPRESS_BLOCKS				\
 					_IOR(F2FS_IOCTL_MAGIC, 19, __u64)
+#define F2FS_IOC_SEC_TRIM_FILE		_IOW(F2FS_IOCTL_MAGIC, 20, __u32)
 
 #define F2FS_IOC_GET_VOLUME_NAME	FS_IOC_GETFSLABEL
 #define F2FS_IOC_SET_VOLUME_NAME	FS_IOC_SETFSLABEL
@@ -453,6 +454,13 @@ static inline bool __has_cursum_space(struct f2fs_journal *journal,
 #define F2FS_GOING_DOWN_METAFLUSH	0x3	/* going down with meta flush */
 #define F2FS_GOING_DOWN_NEED_FSCK	0x4	/* going down to trigger fsck */
 
+/*
+ * Flags used by F2FS_IOC_SEC_TRIM_FILE
+ */
+#define F2FS_TRIM_FILE_DISCARD		0x1	/* send discard command */
+#define F2FS_TRIM_FILE_ZEROOUT		0x2	/* zero out */
+#define F2FS_TRIM_FILE_MASK		0x3
+
 #if defined(__KERNEL__) && defined(CONFIG_COMPAT)
 /*
  * ioctl commands in 32 bit emulation
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index dfa1ac2d751a..df5149a4a627 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -3749,6 +3749,152 @@ static int f2fs_reserve_compress_blocks(struct file *filp, unsigned long arg)
 	return ret;
 }
 
+static int f2fs_secure_erase(struct block_device *bdev, block_t block,
+					block_t len, u32 flags)
+{
+	struct request_queue *q = bdev_get_queue(bdev);
+	sector_t sector = SECTOR_FROM_BLOCK(block);
+	sector_t nr_sects = SECTOR_FROM_BLOCK(len);
+	int ret = 0;
+
+	if (!q)
+		return -ENXIO;
+
+	if (flags & F2FS_TRIM_FILE_DISCARD)
+		ret = blkdev_issue_discard(bdev, sector, nr_sects, GFP_NOFS,
+						blk_queue_secure_erase(q) ?
+						BLKDEV_DISCARD_SECURE : 0);
+
+	if (!ret && flags & F2FS_TRIM_FILE_ZEROOUT)
+		ret = blkdev_issue_zeroout(bdev, sector, nr_sects, GFP_NOFS, 0);
+
+	return ret;
+}
+
+static int f2fs_sec_trim_file(struct file *filp, unsigned long arg)
+{
+	struct inode *inode = file_inode(filp);
+	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+	struct address_space *mapping = inode->i_mapping;
+	struct block_device *prev_bdev = NULL;
+	loff_t file_size;
+	pgoff_t index, pg_start = 0, pg_end;
+	block_t prev_block = 0, len = 0;
+	u32 flags;
+	int ret = 0;
+
+	if (!S_ISREG(inode->i_mode) || f2fs_is_atomic_file(inode) ||
+			f2fs_compressed_file(inode))
+		return -EINVAL;
+
+	if (f2fs_readonly(sbi->sb))
+		return -EROFS;
+
+	if (f2fs_lfs_mode(sbi))
+		return -EOPNOTSUPP;
+
+	if (get_user(flags, (u32 __user *)arg))
+		return -EFAULT;
+	if (!(flags & F2FS_TRIM_FILE_MASK))
+		return -EINVAL;
+
+	if (flags & F2FS_TRIM_FILE_DISCARD && !f2fs_hw_support_discard(sbi))
+		return -EOPNOTSUPP;
+
+	ret = mnt_want_write_file(filp);
+	if (ret)
+		return ret;
+
+	inode_lock(inode);
+
+	file_size = i_size_read(inode);
+	if (!file_size)
+		goto err;
+	pg_end = (pgoff_t)round_up(file_size, PAGE_SIZE) >> PAGE_SHIFT;
+
+	ret = f2fs_convert_inline_inode(inode);
+	if (ret)
+		goto err;
+
+	down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
+	down_write(&F2FS_I(inode)->i_mmap_sem);
+
+	ret = filemap_write_and_wait(mapping);
+	if (ret)
+		goto out;
+
+	truncate_inode_pages(mapping, 0);
+
+	for (index = pg_start; index < pg_end;) {
+		struct dnode_of_data dn;
+		unsigned int end_offset;
+
+		set_new_dnode(&dn, inode, NULL, NULL, 0);
+		ret = f2fs_get_dnode_of_data(&dn, index, LOOKUP_NODE);
+		if (ret)
+			goto out;
+
+		end_offset = ADDRS_PER_PAGE(dn.node_page, inode);
+		if (pg_end < end_offset + index)
+			end_offset = pg_end - index;
+
+		for (; dn.ofs_in_node < end_offset;
+				dn.ofs_in_node++, index++) {
+			struct block_device *cur_bdev;
+			block_t blkaddr = f2fs_data_blkaddr(&dn);
+
+			if (__is_valid_data_blkaddr(blkaddr)) {
+				if (!f2fs_is_valid_blkaddr(F2FS_I_SB(inode),
+					blkaddr, DATA_GENERIC_ENHANCE)) {
+					ret = -EFSCORRUPTED;
+					goto out;
+				}
+			} else
+				continue;
+
+			cur_bdev = f2fs_target_device(sbi, blkaddr, NULL);
+			if (f2fs_is_multi_device(sbi)) {
+				int i = f2fs_target_device_index(sbi, blkaddr);
+
+				blkaddr -= FDEV(i).start_blk;
+			}
+
+			if (len) {
+				if (prev_bdev == cur_bdev &&
+					blkaddr == prev_block + len) {
+					len++;
+				} else {
+					ret = f2fs_secure_erase(prev_bdev,
+							prev_block, len, flags);
+					if (ret)
+						goto out;
+
+					len = 0;
+				}
+			}
+
+			if (!len) {
+				prev_bdev = cur_bdev;
+				prev_block = blkaddr;
+				len = 1;
+			}
+		}
+
+		f2fs_put_dnode(&dn);
+	}
+
+	if (len)
+		ret = f2fs_secure_erase(prev_bdev, prev_block, len, flags);
+out:
+	up_write(&F2FS_I(inode)->i_mmap_sem);
+	up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
+err:
+	inode_unlock(inode);
+	mnt_drop_write_file(filp);
+
+	return ret;
+}
+
 long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
 	if (unlikely(f2fs_cp_error(F2FS_I_SB(file_inode(filp)))))
@@ -3835,6 +3981,8 @@ long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 		return f2fs_release_compress_blocks(filp, arg);
 	case F2FS_IOC_RESERVE_COMPRESS_BLOCKS:
 		return f2fs_reserve_compress_blocks(filp, arg);
+	case F2FS_IOC_SEC_TRIM_FILE:
+		return f2fs_sec_trim_file(filp, arg);
 	default:
 		return -ENOTTY;
 	}
@@ -4004,6 +4152,7 @@ long f2fs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	case F2FS_IOC_GET_COMPRESS_BLOCKS:
 	case F2FS_IOC_RELEASE_COMPRESS_BLOCKS:
 	case F2FS_IOC_RESERVE_COMPRESS_BLOCKS:
+	case F2FS_IOC_SEC_TRIM_FILE:
 		break;
 	default:
 		return -ENOIOCTLCMD;
-- 
2.27.0.278.ge193c7cf3a9-goog