From: Dylan Yudaken dylany@fb.com
commit d34e1e5b396a0dbaa4a29b7138df662cfb9d8e8e upstream.
Update kiocb->ki_pos at execution time rather than in io_prep_rw(). io_prep_rw() happens before the job is enqueued to a worker and so the offset might be read multiple times before being executed once.
Ensures that the file position in a set of _linked_ SQEs will be only obtained after earlier SQEs have completed, and so will include their incremented file position.
Signed-off-by: Dylan Yudaken dylany@fb.com Reviewed-by: Pavel Begunkov asml.silence@gmail.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- io_uring/io_uring.c | 26 ++++++++++++++++++-------- 1 file changed, 18 insertions(+), 8 deletions(-)
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index d8926475cd88..eaf8463c9b14 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -2919,14 +2919,6 @@ static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe, req->flags |= REQ_F_ISREG;
kiocb->ki_pos = READ_ONCE(sqe->off); - if (kiocb->ki_pos == -1) { - if (!(file->f_mode & FMODE_STREAM)) { - req->flags |= REQ_F_CUR_POS; - kiocb->ki_pos = file->f_pos; - } else { - kiocb->ki_pos = 0; - } - } kiocb->ki_hint = ki_hint_validate(file_write_hint(kiocb->ki_filp)); kiocb->ki_flags = iocb_flags(kiocb->ki_filp); ret = kiocb_set_rw_flags(kiocb, READ_ONCE(sqe->rw_flags)); @@ -3008,6 +3000,20 @@ static inline void io_rw_done(struct kiocb *kiocb, ssize_t ret) } }
+static inline void io_kiocb_update_pos(struct io_kiocb *req) +{ + struct kiocb *kiocb = &req->rw.kiocb; + + if (kiocb->ki_pos == -1) { + if (!(req->file->f_mode & FMODE_STREAM)) { + req->flags |= REQ_F_CUR_POS; + kiocb->ki_pos = req->file->f_pos; + } else { + kiocb->ki_pos = 0; + } + } +} + static void kiocb_done(struct kiocb *kiocb, ssize_t ret, unsigned int issue_flags) { @@ -3563,6 +3569,8 @@ static int io_read(struct io_kiocb *req, unsigned int issue_flags) return ret ?: -EAGAIN; }
+ io_kiocb_update_pos(req); + ret = rw_verify_area(READ, req->file, io_kiocb_ppos(kiocb), req->result); if (unlikely(ret)) { kfree(iovec); @@ -3697,6 +3705,8 @@ static int io_write(struct io_kiocb *req, unsigned int issue_flags) (req->flags & REQ_F_ISREG)) goto copy_iov;
+ io_kiocb_update_pos(req); + ret = rw_verify_area(WRITE, req->file, io_kiocb_ppos(kiocb), req->result); if (unlikely(ret)) goto out_free;