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authorPavel Begunkov <asml.silence@gmail.com>2020-11-25 18:41:28 +0000
committerJens Axboe <axboe@kernel.dk>2020-11-26 08:50:21 -0700
commitaf60470347de6ac2b9f0cc3703975a543a3de075 (patch)
tree6b0d7677d948ebb14a02c02fca16c9f63d6644cb /fs
parent9c3a205c5ffa36e96903c2e37eb5f41c0f03c43e (diff)
io_uring: fix files grab/cancel race
When one task is in io_uring_cancel_files() and another is doing io_prep_async_work() a race may happen. That's because after accounting a request inflight in first call to io_grab_identity() it still may fail and go to io_identity_cow(), which migh briefly keep dangling work.identity and not only. Grab files last, so io_prep_async_work() won't fail if it did get into ->inflight_list. note: the bug shouldn't exist after making io_uring_cancel_files() not poking into other tasks' requests. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs')
-rw-r--r--fs/io_uring.c31
1 files changed, 15 insertions, 16 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c
index ff6deffe5aa9..1023f7b44cea 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1313,22 +1313,6 @@ static bool io_grab_identity(struct io_kiocb *req)
return false;
req->work.flags |= IO_WQ_WORK_FSIZE;
}
-
- if (!(req->work.flags & IO_WQ_WORK_FILES) &&
- (def->work_flags & IO_WQ_WORK_FILES) &&
- !(req->flags & REQ_F_NO_FILE_TABLE)) {
- if (id->files != current->files ||
- id->nsproxy != current->nsproxy)
- return false;
- atomic_inc(&id->files->count);
- get_nsproxy(id->nsproxy);
- req->flags |= REQ_F_INFLIGHT;
-
- spin_lock_irq(&ctx->inflight_lock);
- list_add(&req->inflight_entry, &ctx->inflight_list);
- spin_unlock_irq(&ctx->inflight_lock);
- req->work.flags |= IO_WQ_WORK_FILES;
- }
#ifdef CONFIG_BLK_CGROUP
if (!(req->work.flags & IO_WQ_WORK_BLKCG) &&
(def->work_flags & IO_WQ_WORK_BLKCG)) {
@@ -1370,6 +1354,21 @@ static bool io_grab_identity(struct io_kiocb *req)
}
spin_unlock(&current->fs->lock);
}
+ if (!(req->work.flags & IO_WQ_WORK_FILES) &&
+ (def->work_flags & IO_WQ_WORK_FILES) &&
+ !(req->flags & REQ_F_NO_FILE_TABLE)) {
+ if (id->files != current->files ||
+ id->nsproxy != current->nsproxy)
+ return false;
+ atomic_inc(&id->files->count);
+ get_nsproxy(id->nsproxy);
+ req->flags |= REQ_F_INFLIGHT;
+
+ spin_lock_irq(&ctx->inflight_lock);
+ list_add(&req->inflight_entry, &ctx->inflight_list);
+ spin_unlock_irq(&ctx->inflight_lock);
+ req->work.flags |= IO_WQ_WORK_FILES;
+ }
return true;
}