Thread (43 messages) 43 messages, 3 authors, 2025-10-10

Re: [PATCH v2 09/15] blktrace: add definitions for struct blk_io_trace2

From: Christoph Hellwig <hch@lst.de>
Date: 2025-10-03 07:31:19
Also in: linux-block, lkml

On Thu, Sep 25, 2025 at 05:02:25PM +0200, Johannes Thumshirn wrote:
quoted hunk ↗ jump to hunk
Add definitions for the extended version of the blktrace protocol using a
wider action type to be able to record new actions in the kernel.

Signed-off-by: Johannes Thumshirn <redacted>
---
 include/uapi/linux/blktrace_api.h | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)
diff --git a/include/uapi/linux/blktrace_api.h b/include/uapi/linux/blktrace_api.h
index a3b1f35ac026..d58ef484de49 100644
--- a/include/uapi/linux/blktrace_api.h
+++ b/include/uapi/linux/blktrace_api.h
@@ -94,6 +94,7 @@ enum blktrace_notify {
 
 #define BLK_IO_TRACE_MAGIC	0x65617400
 #define BLK_IO_TRACE_VERSION	0x07
+#define BLK_IO_TRACE2_VERSION	0x08
 
 /*
  * The trace itself
@@ -113,6 +114,21 @@ struct blk_io_trace {
 	/* cgroup id will be stored here if exists */
 };
 
+struct blk_io_trace2 {
+	__u32 magic;		/* MAGIC << 8 | BLK_IO_TRACE2_VERSION */
+	__u32 sequence;		/* event number */
+	__u64 time;		/* in nanoseconds */
+	__u64 sector;		/* disk offset */
+	__u32 bytes;		/* transfer length */
+	__u32 pid;		/* who did it */
+	__u64 action;		/* what happened */
+	__u32 device;		/* device number */
+	__u32 cpu;		/* on what cpu did it happen */
+	__u16 error;		/* completion error */
+	__u16 pdu_len;		/* length of data after this trace */
+	__u8 pad[8];
This will cause mismatching sizes between x86_32 and other
architectures because the size is not 8-byte aligned.  You'll need
to add or remove 4 bytes of padding to ensure that.

I really wish we could have good helpers to check for that.
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