On Mon, Nov 27, 2017 at 10:34:27AM +0800, Xiao Yang wrote:
> I got the following message when running generic/465 in ext4 data=journal mode
> ---------------------------------------------------------------
> QA output created by 465
> non-aio dio test
> encounter an error: block 0 offset 4096, content 62
> encounter an error: block 0 offset 122880, content 62
> encounter an error: block 0 offset 274432, content 62
> encounter an error: block 0 offset 86016, content 62
> aio-dio test
> encounter an error: block 0 offset 28672, content 62
> encounter an error: block 0 offset 12288, content 62
> encounter an error: block 2 offset 16384, content 62
> encounter an error: block 1 offset 565248, content 62
> ---------------------------------------------------------------
>
> In ext4 data=journal mode, direct read will fall back to buffer read, and buffer
> read doesn't take inode lock, so it doesn't need to wait for the writer to finish
> first and sees the intermediate inode size and returns data less than 1M.
>
> We can just check the actual read data instead of the whole read buffer.
>
> Signed-off-by: Xiao Yang <yangx.jy@xxxxxxxxxxxxxx>
> ---
> src/aio-dio-regress/aio-dio-append-write-read-race.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/src/aio-dio-regress/aio-dio-append-write-read-race.c b/src/aio-dio-regress/aio-dio-append-write-read-race.c
> index 8f94d50..eaec784 100644
> --- a/src/aio-dio-regress/aio-dio-append-write-read-race.c
> +++ b/src/aio-dio-regress/aio-dio-append-write-read-race.c
> @@ -43,6 +43,7 @@ struct io_data {
> off_t offset;
> char *buf;
> int use_aio;
> + size_t act_sz;
I think this should be a signed value, as pread returns ssize_t. And
maybe rename the variable to read_sz? Otherwise looks fine to me. And I
can do the updates on commit, if there's no further review comments.
Thanks,
Eryu
> };
>
> int reader_ready = 0;
> @@ -57,15 +58,14 @@ static void usage(const char *prog)
> static void *reader(void *arg)
> {
> struct io_data *data = (struct io_data *)arg;
> - int ret;
>
> memset(data->buf, 'b', data->blksize);
> reader_ready = 1;
> do {
> - ret = pread(data->fd, data->buf, data->blksize, data->offset);
> - if (ret < 0)
> + data->act_sz = pread(data->fd, data->buf, data->blksize, data->offset);
> + if (data->act_sz < 0)
> perror("read file");
> - } while (ret <= 0);
> + } while (data->act_sz <= 0);
>
> return NULL;
> }
> @@ -203,7 +203,7 @@ int main(int argc, char *argv[])
> goto err;
> }
>
> - for (j = 0; j < blksize; j++) {
> + for (j = 0; j < rdata.act_sz; j++) {
> if (rdata.buf[j] != 'a') {
> fail("encounter an error: "
> "block %d offset %d, content %x\n",
> --
> 1.8.3.1
>
>
>
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