From 81626165ada62e660cfc0eaa80dfe0a6f53dba38 Mon Sep 17 00:00:00 2001
From: Stefan Metzmacher <metze@samba.org>
Date: Wed, 6 May 2020 03:12:24 -0700
Subject: [PATCH] HACK vfs_io_uring: add debugging for bug 14361

---
 source3/modules/vfs_io_uring.c | 93 +++++++++++++++++++++++++++++++++-
 1 file changed, 92 insertions(+), 1 deletion(-)

diff --git a/source3/modules/vfs_io_uring.c b/source3/modules/vfs_io_uring.c
index b409d0753379..1a9b8e442213 100644
--- a/source3/modules/vfs_io_uring.c
+++ b/source3/modules/vfs_io_uring.c
@@ -35,6 +35,8 @@ struct vfs_io_uring_config {
 	struct tevent_fd *fde;
 	struct vfs_io_uring_request *queue;
 	struct vfs_io_uring_request *pending;
+	bool check_ff;
+	size_t truncate_pread;
 };
 
 struct vfs_io_uring_request {
@@ -48,6 +50,11 @@ struct vfs_io_uring_request {
 	struct timespec start_time;
 	struct timespec end_time;
 	SMBPROFILE_BYTES_ASYNC_STATE(profile_bytes);
+	const char *opname;
+	struct files_struct *fsp;
+	uint8_t *data;
+	size_t len;
+	off_t ofs;
 };
 
 static void vfs_io_uring_finish_req(struct vfs_io_uring_request *cur,
@@ -69,6 +76,77 @@ static void vfs_io_uring_finish_req(struct vfs_io_uring_request *cur,
 	SMBPROFILE_BYTES_ASYNC_SET_IDLE(cur->profile_bytes);
 	cur->end_time = end_time;
 
+	if (cur->opname == NULL) {
+		goto done;
+	}
+
+	if (cqe->res < 0) {
+		goto done;
+	}
+
+	if ((size_t)cqe->res != (size_t)cur->len) {
+		DBG_ERR("Invalid %s ofs=%zu (0x%zx) len=%zu (0x%zx) nread=%zu (0x%zu) eof=%zu (0x%zx) blks=%zu blocks=%zu %s %s\n",
+			cur->opname,
+			(size_t)cur->ofs,
+			(size_t)cur->ofs,
+			(size_t)cur->len,
+			(size_t)cur->len,
+			(size_t)cqe->res,
+			(size_t)cqe->res,
+			(size_t)cur->fsp->fsp_name->st.st_ex_size,
+			(size_t)cur->fsp->fsp_name->st.st_ex_size,
+			(size_t)cur->fsp->fsp_name->st.st_ex_blksize,
+			(size_t)cur->fsp->fsp_name->st.st_ex_blocks,
+			fsp_str_dbg(cur->fsp),
+			fsp_fnum_dbg(cur->fsp));
+	} else {
+		DBG_WARNING("%s ofs=%zu (0x%zx) len=%zu (0x%zx) nread=%zu (0x%zu) eof=%zu (0x%zx) blks=%zu blocks=%zu %s %s\n",
+			cur->opname,
+			(size_t)cur->ofs,
+			(size_t)cur->ofs,
+			(size_t)cur->len,
+			(size_t)cur->len,
+			(size_t)cqe->res,
+			(size_t)cqe->res,
+			(size_t)cur->fsp->fsp_name->st.st_ex_size,
+			(size_t)cur->fsp->fsp_name->st.st_ex_size,
+			(size_t)cur->fsp->fsp_name->st.st_ex_blksize,
+			(size_t)cur->fsp->fsp_name->st.st_ex_blocks,
+			fsp_str_dbg(cur->fsp),
+			fsp_fnum_dbg(cur->fsp));
+	}
+
+	if (cur->config->check_ff) {
+		size_t i;
+		size_t len = MIN(cur->len, ((size_t)cqe->res));
+		for (i = 0; i < len; i++) {
+			size_t fofs;
+			if (cur->data[i] == 0xff) {
+				continue;
+			}
+
+			fofs = cur->ofs + i;
+		DBG_ERR("%s invalid byte[0x%x] at fofs=%zu (0x%zx) ofs=%zu (0x%zx) len=%zu (0x%zx) nread=%zu (0x%zu) eof=%zu (0x%zx) blks=%zu blocks=%zu %s %s\n",
+			cur->opname,
+			cur->data[i],
+			(size_t)fofs,
+			(size_t)fofs,
+			(size_t)cur->ofs,
+			(size_t)cur->ofs,
+			(size_t)cur->len,
+			(size_t)cur->len,
+			(size_t)cqe->res,
+			(size_t)cqe->res,
+			(size_t)cur->fsp->fsp_name->st.st_ex_size,
+			(size_t)cur->fsp->fsp_name->st.st_ex_size,
+			(size_t)cur->fsp->fsp_name->st.st_ex_blksize,
+			(size_t)cur->fsp->fsp_name->st.st_ex_blocks,
+			fsp_str_dbg(cur->fsp),
+			fsp_fnum_dbg(cur->fsp));
+			break;
+		}
+	}
+done:
 	/*
 	 * We rely on being inside the _send() function
 	 * or tevent_req_defer_callback() being called
@@ -216,6 +294,14 @@ static int vfs_io_uring_connect(vfs_handle_struct *handle, const char *service,
 		return -1;
 	}
 
+	config->check_ff = lp_parm_bool(SNUM(handle->conn),
+			     "io_uring",
+			     "check_ff",
+			     false);
+	config->truncate_pread = lp_parm_ulonglong(SNUM(handle->conn),
+				    "io_uring",
+				    "truncate_pread",
+				    UINT64_MAX);
 	return 0;
 }
 
@@ -319,13 +405,18 @@ static struct tevent_req *vfs_io_uring_pread_send(struct vfs_handle_struct *hand
 	state->ur.config = config;
 	state->ur.req = req;
 	state->ur.state = state;
+	state->ur.opname = "pread";
+	state->ur.fsp = fsp;
+	state->ur.data = data;
+	state->ur.len = n;
+	state->ur.ofs = offset;
 
 	SMBPROFILE_BYTES_ASYNC_START(syscall_asys_pread, profile_p,
 				     state->ur.profile_bytes, n);
 	SMBPROFILE_BYTES_ASYNC_SET_IDLE(state->ur.profile_bytes);
 
 	state->iov.iov_base = (void *)data;
-	state->iov.iov_len = n;
+	state->iov.iov_len = MIN(n, config->truncate_pread);
 	io_uring_prep_readv(&state->ur.sqe,
 			    fsp->fh->fd,
 			    &state->iov, 1,
-- 
2.17.1