On 2015/6/2 7:01, Jaegeuk Kim wrote: > On Mon, Jun 01, 2015 at 07:55:08PM +0800, He YunLei wrote: >> Hi Jaegeuk, >> >> We run ltp testcase with f2fs and obtain a TFAIL in diotest4, the result in >> detail is >> as fallow: >> >> dio04 >> >> <<<test_start>>> >> tag=dio04 stime=1432278894 >> cmdline="diotest4" >> contacts="" >> analysis=exit >> <<<test_output>>> >> diotest4 1 TPASS : Negative Offset >> diotest4 2 TPASS : removed >> diotest4 3 TFAIL : diotest4.c:129: write allows odd count.returns 1: >> Success >> diotest4 4 TFAIL : diotest4.c:183: Odd count of read and write >> diotest4 5 TPASS : Read beyond the file size >> ...... >> >> the result of ext4 with same environment: >> >> dio04 >> >> <<<test_start>>> >> tag=dio04 stime=1432259643 >> cmdline="diotest4" >> contacts="" >> analysis=exit >> <<<test_output>>> >> diotest4 1 TPASS : Negative Offset >> diotest4 2 TPASS : removed >> diotest4 3 TPASS : Odd count of read and write >> diotest4 4 TPASS : Read beyond the file size >> ...... >> >> Does f2fs allow dwrite with non-aligned offset and size? I check the code >> and found >> dwrite with non-aligned offset and size will turn into buffered write. >> Whether it will >> have some impact on user layer applications? > > It's not a big deal to return -EINVAL. > When I take a look at other filesystem behaviors, it seems there is no > restriction. >
Ext4 do a check in the function do_blockdev_direct_IO: if (align & blocksize_mask) { if (bdev) blkbits = blksize_bits(bdev_logical_block_size(bdev)); blocksize_mask = (1 << blkbits) - 1; if (align & blocksize_mask) goto out; } It will return -EINVAL if the alignment is not satisfied. In f2fs, it do the check by check_direct_IO() before blockdev_direct_IO(). The difference between the two methods is whether turn dwrite with non-aligned offset and size into buffered write. I am not very clear which one is better! Thanks, He >> >> I wrote a patch, not well tested, how do you think of it? > > Returning the error number would be good to me. > Could you write and sumbit a complete one? > > Thanks, > >> >> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c >> index 9bedfa8..ba5d94c 100644 >> --- a/fs/f2fs/data.c >> +++ b/fs/f2fs/data.c >> @@ -2010,8 +2010,9 @@ static ssize_t f2fs_direct_IO(struct kiocb *iocb, >> struct iov_iter *iter, >> if (f2fs_encrypted_inode(inode) && S_ISREG(inode->i_mode)) >> return 0; >> >> - if (check_direct_IO(inode, iter, offset)) >> - return 0; >> + err = check_direct_IO(inode, iter, offset) >> + if (err) >> + return -EINVAL; >> >> trace_f2fs_direct_IO_enter(inode, offset, count, iov_iter_rw(iter)); >> >> I wish you and other developers in this list could help me in a correct way. >> >> Thanks, >> He > > . > ------------------------------------------------------------------------------ _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel