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authorJens Axboe <axboe@kernel.dk>2020-11-14 02:48:44 +0300
committerJens Axboe <axboe@kernel.dk>2020-11-14 20:22:30 +0300
commit944d1444d53f5a213457e5096db370cfd06923d4 (patch)
tree3fcded51bd23c96fa0499124b8079dee6ef15be1 /fs
parent8d4c3e76e3be11a64df95ddee52e99092d42fc19 (diff)
downloadlinux-944d1444d53f5a213457e5096db370cfd06923d4.tar.xz
io_uring: handle -EOPNOTSUPP on path resolution
Any attempt to do path resolution on /proc/self from an async worker will yield -EOPNOTSUPP. We can safely do that resolution from the task itself, and without blocking, so retry it from there. Ideally io_uring would know this upfront and not have to go through the worker thread to find out, but that doesn't currently seem feasible. Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs')
-rw-r--r--fs/io_uring.c19
1 files changed, 18 insertions, 1 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c
index c77584de68d7..f05978a74ce1 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -478,6 +478,7 @@ struct io_sr_msg {
struct io_open {
struct file *file;
int dfd;
+ bool ignore_nonblock;
struct filename *filename;
struct open_how how;
unsigned long nofile;
@@ -3796,6 +3797,7 @@ static int __io_openat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe
return ret;
}
req->open.nofile = rlimit(RLIMIT_NOFILE);
+ req->open.ignore_nonblock = false;
req->flags |= REQ_F_NEED_CLEANUP;
return 0;
}
@@ -3839,7 +3841,7 @@ static int io_openat2(struct io_kiocb *req, bool force_nonblock)
struct file *file;
int ret;
- if (force_nonblock)
+ if (force_nonblock && !req->open.ignore_nonblock)
return -EAGAIN;
ret = build_open_flags(&req->open.how, &op);
@@ -3854,6 +3856,21 @@ static int io_openat2(struct io_kiocb *req, bool force_nonblock)
if (IS_ERR(file)) {
put_unused_fd(ret);
ret = PTR_ERR(file);
+ /*
+ * A work-around to ensure that /proc/self works that way
+ * that it should - if we get -EOPNOTSUPP back, then assume
+ * that proc_self_get_link() failed us because we're in async
+ * context. We should be safe to retry this from the task
+ * itself with force_nonblock == false set, as it should not
+ * block on lookup. Would be nice to know this upfront and
+ * avoid the async dance, but doesn't seem feasible.
+ */
+ if (ret == -EOPNOTSUPP && io_wq_current_is_worker()) {
+ req->open.ignore_nonblock = true;
+ refcount_inc(&req->refs);
+ io_req_task_queue(req);
+ return 0;
+ }
} else {
fsnotify_open(file);
fd_install(ret, file);