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
.
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