Messages in this thread | | | Date | Thu, 2 Dec 2021 10:13:09 -0800 | From | Jaegeuk Kim <> | Subject | Re: [f2fs-dev] [PATCH 2/6] f2fs: do not expose unwritten blocks to user by DIO |
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On 12/02, Chao Yu wrote: > On 2021/11/17 5:45, Jaegeuk Kim wrote: > > DIO preallocates physical blocks before writing data, but if an error occurrs > > or power-cut happens, we can see block contents from the disk. This patch tries > > to fix it by 1) turning to buffered writes for DIO into holes, 2) truncating > > unwritten blocks from error or power-cut. > > > > Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> > > --- > > fs/f2fs/data.c | 5 ++++- > > fs/f2fs/f2fs.h | 5 +++++ > > fs/f2fs/file.c | 24 +++++++++++++++++++++++- > > 3 files changed, 32 insertions(+), 2 deletions(-) > > > > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c > > index 3b27fb7daa8b..7ac1a39fcad2 100644 > > --- a/fs/f2fs/data.c > > +++ b/fs/f2fs/data.c > > @@ -1543,8 +1543,11 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map, > > flag != F2FS_GET_BLOCK_DIO); > > err = __allocate_data_block(&dn, > > map->m_seg_type); > > - if (!err) > > + if (!err) { > > + if (flag == F2FS_GET_BLOCK_PRE_DIO) > > + file_need_truncate(inode); > > set_inode_flag(inode, FI_APPEND_WRITE); > > + } > > } > > if (err) > > goto sync_out; > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > > index be871a79c634..14bea669f87e 100644 > > --- a/fs/f2fs/f2fs.h > > +++ b/fs/f2fs/f2fs.h > > @@ -654,6 +654,7 @@ enum { > > #define FADVISE_KEEP_SIZE_BIT 0x10 > > #define FADVISE_HOT_BIT 0x20 > > #define FADVISE_VERITY_BIT 0x40 > > +#define FADVISE_TRUNC_BIT 0x80 > > #define FADVISE_MODIFIABLE_BITS (FADVISE_COLD_BIT | FADVISE_HOT_BIT) > > @@ -681,6 +682,10 @@ enum { > > #define file_is_verity(inode) is_file(inode, FADVISE_VERITY_BIT) > > #define file_set_verity(inode) set_file(inode, FADVISE_VERITY_BIT) > > +#define file_should_truncate(inode) is_file(inode, FADVISE_TRUNC_BIT) > > +#define file_need_truncate(inode) set_file(inode, FADVISE_TRUNC_BIT) > > +#define file_dont_truncate(inode) clear_file(inode, FADVISE_TRUNC_BIT) > > + > > #define DEF_DIR_LEVEL 0 > > enum { > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c > > index 4bf77a5bf998..ec8de0662437 100644 > > --- a/fs/f2fs/file.c > > +++ b/fs/f2fs/file.c > > @@ -960,10 +960,21 @@ int f2fs_setattr(struct user_namespace *mnt_userns, struct dentry *dentry, > > down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); > > filemap_invalidate_lock(inode->i_mapping); > > + /* > > + * Truncate stale preallocated blocks used by the previous DIO. > > + */ > > + if (file_should_truncate(inode)) { > > + err = f2fs_truncate(inode); > > + if (err) > > + goto out_unlock; > > + file_dont_truncate(inode); > > + } > > + > > truncate_setsize(inode, attr->ia_size); > > if (attr->ia_size <= old_size) > > err = f2fs_truncate(inode); > > +out_unlock: > > /* > > * do not trim all blocks after i_size if target size is > > * larger than i_size. > > @@ -4257,6 +4268,13 @@ static int f2fs_preallocate_blocks(struct kiocb *iocb, struct iov_iter *iter) > > /* If it will be an out-of-place direct write, don't bother. */ > > if (dio && f2fs_lfs_mode(sbi)) > > return 0; > > + /* > > + * Don't preallocate holes aligned to DIO_SKIP_HOLES which turns into > > + * buffered IO, if DIO meets any holes. > > + */ > > + if (dio && i_size_read(inode) && > > + (F2FS_BYTES_TO_BLK(pos) < F2FS_BLK_ALIGN(i_size_read(inode)))) > > + return 0; > > /* No-wait I/O can't allocate blocks. */ > > if (iocb->ki_flags & IOCB_NOWAIT) > > @@ -4366,10 +4384,14 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from) > > if (preallocated > 0 && i_size_read(inode) < target_size) { > > down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); > > filemap_invalidate_lock(inode->i_mapping); > > - f2fs_truncate(inode); > > + if (!f2fs_truncate(inode)) > > + file_dont_truncate(inode); > > filemap_invalidate_unlock(inode->i_mapping); > > up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); > > + } else { > > + file_dont_truncate(inode); > > How about this case: > > - touch file > - DIO write [0, 8kb] to file > - preallocate 2 physical blocks > - set FADVISE_TRUNC_BIT > - SPO > - BUFIO write [0, 4kb] to file > - file_dont_truncate -- it leaks unwritten [4kb, 8kb] to user after > truncating file to 8kb
i_size should be 4kb, no?
> > Thanks, > > > } > > + > > clear_inode_flag(inode, FI_PREALLOCATED_ALL); > > if (ret > 0) > >
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