Messages in this thread | | | From | Daeho Jeong <> | Date | Tue, 9 Jun 2020 10:30:23 +0900 | Subject | Re: [f2fs-dev] [PATCH] f2fs: add F2FS_IOC_TRIM_FILE ioctl |
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Like the discussion, I'll add a flag to select discard and/or zero out. We need to send the discard first between those, because we'll send the discard to a zero-ed new block, if we zero out first.
2020년 6월 9일 (화) 오전 10:16, Chao Yu <yuchao0@huawei.com>님이 작성: > > On 2020/6/8 21:07, Jaegeuk Kim wrote: > > On 06/08, Chao Yu wrote: > >> On 2020/6/8 15:19, Daeho Jeong wrote: > >>> Yes, I agree with you about each vendor has different implementation on discard. > >>> So, we might be gonna use the combination of zeroing and send discards > >>> for a more > >>> secure solution. :) > >> > >> IIRC, current solution is: > >> > >> - pin file > >> - get all block addresses of file > >> - write zero to block addresses > >> - issue discard > >> > >> Is that correct? > >> > >> Could we handle those logic (zero out & discard) in new interface > >> (may be named as {F2FS,EXT4}_IOC_SEC_TRIM_FILE)? then userspace logic > >> could be quite simple later, and also memcpy could be avoid to make > >> destruction process more efficient. > > > > What about adding a flag to determine calling unmap and/or zero out? > > Better. :) > > Thanks, > > > > >> > >> Just raw proposal. :) > >> > >> Thanks, > >> > >>> I think we still need a discard interface to unmap from the mapping > >>> table of the storage device side. > >>> > >>> Thanks, > >>> > >>> 2020년 6월 8일 (월) 오후 3:57, Chao Yu <yuchao0@huawei.com>님이 작성: > >>>> > >>>> On 2020/6/8 11:36, Daeho Jeong wrote: > >>>>> Yes, this is for security key destruction. > >>>>> > >>>>> AFAIK, discard will unmap the data block and, after done it, > >>>>> we can read either zero data or garbage data from that block depending > >>>>> on eMMC/UFS. > >>>> > >>>> Since spec didn't restrict how vendor implement the erase interface, so > >>>> in order to enhance performance of discard interface, vendor could implement > >>>> it as an async one, which may not zero mapping entry(L1 table), instead, it > >>>> could set related bitmap to invalid that mapping entry, than later if device > >>>> allow user to access that invalid mapping entry, key info may be explosed, > >>>> > >>>> It's completely up to how vendor implement the interface, so I think there is > >>>> still risk to use discard. > >>>> > >>>> Thanks, > >>>> > >>>>> In a view point of read data, it might be the same with zeroing the data block. > >>>>> However, since we can even unmap that block, I believe discard is > >>>>> safer than zeroing out. > >>>>> > >>>>> 2020년 6월 8일 (월) 오전 11:46, Chao Yu <yuchao0@huawei.com>님이 작성: > >>>>>> > >>>>>> On 2020/6/5 12:27, Daeho Jeong wrote: > >>>>>>> From: Daeho Jeong <daehojeong@google.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@google.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; > >>>>>>> > >>>>> . > >>>>> > >>> . > >>> > >> > >> > >> _______________________________________________ > >> Linux-f2fs-devel mailing list > >> Linux-f2fs-devel@lists.sourceforge.net > >> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel > > . > >
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