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Date: Mon, 8 Jun 2020 10:46:07 +0800
From: Chao Yu <yuchao0@...wei.com>
To: Daeho Jeong <daeho43@...il.com>, <linux-kernel@...r.kernel.org>,
<linux-f2fs-devel@...ts.sourceforge.net>, <kernel-team@...roid.com>
CC: Daeho Jeong <daehojeong@...gle.com>
Subject: Re: [f2fs-dev] [PATCH] f2fs: add F2FS_IOC_TRIM_FILE ioctl
On 2020/6/5 12:27, Daeho Jeong wrote:
> From: Daeho Jeong <daehojeong@...gle.com>
>
> Added a new ioctl to send discard commands to whole data area of
> a regular file for security reason.
I guess this interface is introduced for security key destruction, if I'm
right, however, IIRC, discard(erase) semantics in eMMC/UFS spec won't
guarantee that data which was discard could be zeroed out, so after discard,
the key still have risk of exposure. So instead, should we use sb_issue_zeroout()?
Thanks,
>
> Signed-off-by: Daeho Jeong <daehojeong@...gle.com>
> ---
> fs/f2fs/f2fs.h | 1 +
> fs/f2fs/file.c | 129 +++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 130 insertions(+)
>
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index c812fb8e2d9c..9ae81d0fefa0 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_TRIM_FILE _IO(F2FS_IOCTL_MAGIC, 20)
>
> #define F2FS_IOC_GET_VOLUME_NAME FS_IOC_GETFSLABEL
> #define F2FS_IOC_SET_VOLUME_NAME FS_IOC_SETFSLABEL
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index dfa1ac2d751a..58507bb5649c 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -3749,6 +3749,132 @@ static int f2fs_reserve_compress_blocks(struct file *filp, unsigned long arg)
> return ret;
> }
>
> +static int f2fs_trim_file(struct file *filp)
> +{
> + struct inode *inode = file_inode(filp);
> + struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
> + struct address_space *mapping = inode->i_mapping;
> + struct bio *bio = NULL;
> + 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;
> + int ret = 0;
> +
> + if (!f2fs_hw_support_discard(sbi))
> + return -EOPNOTSUPP;
> +
> + if (!S_ISREG(inode->i_mode) || f2fs_is_atomic_file(inode) ||
> + f2fs_compressed_file(inode))
> + return -EINVAL;
> +
> + if (f2fs_readonly(sbi->sb))
> + return -EROFS;
> +
> + 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 = __blkdev_issue_discard(prev_bdev,
> + SECTOR_FROM_BLOCK(prev_block),
> + SECTOR_FROM_BLOCK(len),
> + GFP_NOFS, 0, &bio);
> + if (ret)
> + goto out;
> +> + len = 0;
> + }
> + }
> +
> + if (!len) {
> + prev_bdev = cur_bdev;
> + prev_block = blkaddr;
> + len = 1;
> + }
> + }
> +
> + f2fs_put_dnode(&dn);
> + }
> +
> + if (len)
> + ret = __blkdev_issue_discard(prev_bdev,
> + SECTOR_FROM_BLOCK(prev_block),
> + SECTOR_FROM_BLOCK(len),
> + GFP_NOFS, 0, &bio);
> +out:
> + if (bio) {
> + ret = submit_bio_wait(bio);
> + bio_put(bio);
> + }
> +
> + 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 +3961,8 @@ 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_TRIM_FILE:
> + return f2fs_trim_file(filp);
> default:
> return -ENOTTY;
> }
> @@ -4004,6 +4132,7 @@ 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_TRIM_FILE:
> break;
> default:
> return -ENOIOCTLCMD;
>
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