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io_uring: correctly handle non ->{read,write}_iter() file_operations 

Currently we just -EINVAL a read or write to an fd that isn't backed
by ->read_iter() or ->write_iter(). But we can handle them just fine,
as long as we punt fo async context first.

Implement a simple loop function for doing ->read() or ->write()
instead, and ensure we call it appropriately.

Reported-by: 李通洲 <carter.li@eoitek.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2019-09-23 11:05:34 -06:00
parent 5262f56798
commit 32960613b7
1 changed files with 54 additions and 6 deletions
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60
fs/io_uring.c
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@ -1298,6 +1298,51 @@ static void io_async_list_note(int rw, struct io_kiocb *req, size_t len)
}
}
/*
* For files that don't have ->read_iter() and ->write_iter(), handle them
* by looping over ->read() or ->write() manually.
*/
static ssize_t loop_rw_iter(int rw, struct file *file, struct kiocb *kiocb,
struct iov_iter *iter)
{
ssize_t ret = 0;
/*
* Don't support polled IO through this interface, and we can't
* support non-blocking either. For the latter, this just causes
* the kiocb to be handled from an async context.
*/
if (kiocb->ki_flags & IOCB_HIPRI)
return -EOPNOTSUPP;
if (kiocb->ki_flags & IOCB_NOWAIT)
return -EAGAIN;
while (iov_iter_count(iter)) {
struct iovec iovec = iov_iter_iovec(iter);
ssize_t nr;
if (rw == READ) {
nr = file->f_op->read(file, iovec.iov_base,
iovec.iov_len, &kiocb->ki_pos);
} else {
nr = file->f_op->write(file, iovec.iov_base,
iovec.iov_len, &kiocb->ki_pos);
}
if (nr < 0) {
if (!ret)
ret = nr;
break;
}
ret += nr;
if (nr != iovec.iov_len)
break;
iov_iter_advance(iter, nr);
}
return ret;
}
static int io_read(struct io_kiocb *req, const struct sqe_submit *s,
bool force_nonblock)
{
@ -1315,8 +1360,6 @@ static int io_read(struct io_kiocb *req, const struct sqe_submit *s,
if (unlikely(!(file->f_mode & FMODE_READ)))
return -EBADF;
if (unlikely(!file->f_op->read_iter))
return -EINVAL;
ret = io_import_iovec(req->ctx, READ, s, &iovec, &iter);
if (ret < 0)
@ -1331,7 +1374,11 @@ static int io_read(struct io_kiocb *req, const struct sqe_submit *s,
if (!ret) {
ssize_t ret2;
ret2 = call_read_iter(file, kiocb, &iter);
if (file->f_op->read_iter)
ret2 = call_read_iter(file, kiocb, &iter);
else
ret2 = loop_rw_iter(READ, file, kiocb, &iter);
/*
* In case of a short read, punt to async. This can happen
* if we have data partially cached. Alternatively we can
@ -1376,8 +1423,6 @@ static int io_write(struct io_kiocb *req, const struct sqe_submit *s,
file = kiocb->ki_filp;
if (unlikely(!(file->f_mode & FMODE_WRITE)))
return -EBADF;
if (unlikely(!file->f_op->write_iter))
return -EINVAL;
ret = io_import_iovec(req->ctx, WRITE, s, &iovec, &iter);
if (ret < 0)
@ -1415,7 +1460,10 @@ static int io_write(struct io_kiocb *req, const struct sqe_submit *s,
}
kiocb->ki_flags |= IOCB_WRITE;
ret2 = call_write_iter(file, kiocb, &iter);
if (file->f_op->write_iter)
ret2 = call_write_iter(file, kiocb, &iter);
else
ret2 = loop_rw_iter(WRITE, file, kiocb, &iter);
if (!force_nonblock || ret2 != -EAGAIN) {
io_rw_done(kiocb, ret2);
} else {