From 0f4978d34f42b2af08481f777906dce47c13ef38 Mon Sep 17 00:00:00 2001
From: Akanksha Mahajan <akankshamahajan@fb.com>
Date: Wed, 21 Sep 2022 14:21:59 -0700
Subject: [PATCH] Fix sqe->addr passed in cancel request in io_uring (#10644)

Summary:
Update io_uring_prep_cancel as it is now backward compatible.
Also, io_uring_prep_cancel expects sqe->addr to match with read
request submitted. It's being set wrong which is now fixed in this PR.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10644

Test Plan:
- Ran internally with lastest liburing package and on RocksDB
github repo with older version.
- Ran seekrandom regression to confirm there is no regression.

Reviewed By: anand1976

Differential Revision: D39284229

Pulled By: akankshamahajan15

fbshipit-source-id: fd52cdf23d676da114896163626b75c8ae09c980
---
 HISTORY.md      |  2 ++
 env/fs_posix.cc | 10 ++++++----
 env/io_posix.cc |  4 +++-
 3 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/HISTORY.md b/HISTORY.md
index e725ac9fa..75ed19b2e 100644
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -1,5 +1,7 @@
 # Rocksdb Change Log
 ## Unreleased
+### Bug Fixes
+* Fix a bug in io_uring_prep_cancel in AbortIO API for posix which expects sqe->addr to match with read request submitted and wrong paramter was being passed.
 
 ## 7.7.0 (09/18/2022)
 ### Bug Fixes
diff --git a/env/fs_posix.cc b/env/fs_posix.cc
index e1b1400d0..a6f7b9c08 100644
--- a/env/fs_posix.cc
+++ b/env/fs_posix.cc
@@ -1115,10 +1115,11 @@ class PosixFileSystem : public FileSystem {
       // Prepare the cancel request.
       struct io_uring_sqe* sqe;
       sqe = io_uring_get_sqe(iu);
-      // prep_cancel changed API in liburing, but we need to support both old
-      // and new versions so do it by hand
-      io_uring_prep_cancel(sqe, 0, 0);
-      sqe->addr = reinterpret_cast<uint64_t>(posix_handle);
+
+      // In order to cancel the request, sqe->addr of cancel request should
+      // match with the read request submitted which is posix_handle->iov.
+      io_uring_prep_cancel(sqe, &posix_handle->iov, 0);
+      // Sets sqe->user_data to posix_handle.
       io_uring_sqe_set_data(sqe, posix_handle);
 
       // submit the request.
@@ -1146,6 +1147,7 @@ class PosixFileSystem : public FileSystem {
         }
         assert(cqe != nullptr);
 
+        // Returns cqe->user_data.
         Posix_IOHandle* posix_handle =
             static_cast<Posix_IOHandle*>(io_uring_cqe_get_data(cqe));
         assert(posix_handle->iu == iu);
diff --git a/env/io_posix.cc b/env/io_posix.cc
index 7a23f9e54..59a94acd4 100644
--- a/env/io_posix.cc
+++ b/env/io_posix.cc
@@ -899,8 +899,10 @@ IOStatus PosixRandomAccessFile::ReadAsync(
   struct io_uring_sqe* sqe;
   sqe = io_uring_get_sqe(iu);
 
-  io_uring_prep_readv(sqe, fd_, &posix_handle->iov, 1, posix_handle->offset);
+  io_uring_prep_readv(sqe, fd_, /*sqe->addr=*/&posix_handle->iov,
+                      /*sqe->len=*/1, /*sqe->offset=*/posix_handle->offset);
 
+  // Sets sqe->user_data to posix_handle.
   io_uring_sqe_set_data(sqe, posix_handle);
 
   // Step 4: io_uring_submit