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SubjectRe: Linux 5.19-rc7 liburing test `poll-mshot-overflow.t` and `read-write.t` fail
Date
On Thu, 2022-07-21 at 17:41 +0700, Ammar Faizi wrote:
> On 7/21/22 4:48 PM, Dylan Yudaken wrote:
> > What fs are you using? testing on a fresh XFS fs read-write.t works
> > for
> > me
>
> I am using btrfs.
>
> After I got your email, I tried to run the test on an ext4 directory
> and
> it works fine. But fails on a btrfs directory.
>
> Any idea why does the test fail on a btrfs fs?
>

It seems to be a problem with blocking reads, buffer select and READV.
My guess is that ext4/xfs are not blocking.

in b66e65f41426 ("io_uring: never call io_buffer_select() for a buffer
re-select"), this line was added in __io_iov_buffer_select

- iov[0].iov_len = len;
+ req->rw.len = iov[0].iov_len = len;

Basically stashing the buffer length in rw.len. The problem is that the
next time around that breaks at

if (req->rw.len != 1)
return -EINVAL;


The below fixes it as an example, but it's not great. Maybe someone can
figure out a better patch? Otherwise I can try tomorrow:

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 2b7bb62c7805..d9fa226f8e30 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -647,6 +647,8 @@ struct io_rw {
u64 addr;
u32 len;
rwf_t flags;
+ u64 bufaddr;
+ u32 buflen;
};

struct io_connect {
@@ -3899,7 +3901,7 @@ static ssize_t io_compat_import(struct io_kiocb
*req, struct iovec *iov,
return -ENOBUFS;
req->rw.addr = (unsigned long) buf;
iov[0].iov_base = buf;
- req->rw.len = iov[0].iov_len = (compat_size_t) len;
+ req->rw.buflen = iov[0].iov_len = (compat_size_t) len;
return 0;
}
#endif
@@ -3920,9 +3922,9 @@ static ssize_t __io_iov_buffer_select(struct
io_kiocb *req, struct iovec *iov,
buf = io_buffer_select(req, &len, issue_flags);
if (!buf)
return -ENOBUFS;
- req->rw.addr = (unsigned long) buf;
+ req->rw.bufaddr = (unsigned long) buf;
iov[0].iov_base = buf;
- req->rw.len = iov[0].iov_len = len;
+ req->rw.buflen = iov[0].iov_len = len;
return 0;
}

@@ -3930,8 +3932,8 @@ static ssize_t io_iov_buffer_select(struct
io_kiocb *req, struct iovec *iov,
unsigned int issue_flags)
{
if (req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)) {
- iov[0].iov_base = u64_to_user_ptr(req->rw.addr);
- iov[0].iov_len = req->rw.len;
+ iov[0].iov_base = u64_to_user_ptr(req->rw.bufaddr);
+ iov[0].iov_len = req->rw.buflen;
return 0;
}
if (req->rw.len != 1)
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