On Tue, Nov 25, 2025 at 03:28:30PM +0200, Arye Yurkovsky wrote:
> Devices associated with btrfs volumes are not reverse-translated
> (e.g., btrfsvol:/dev/sdX to sdY).
> Forward translation occurs, creating a path mismatch.
> This causes errors in subsequent btrfs commands.
Sorry for missing this patch last week.
Can you try the attached version instead? There are some problems
with the patch as posted, including that it isn't const correct, but
the attached version should fix those things.
Rich.
> daemon/device-name-translation.c | 27 ++++++++++++++++++++++++++-
> 1 file changed, 26 insertions(+), 1 deletion(-)
>
> diff --git a/daemon/device-name-translation.c
> b/daemon/device-name-translation.c
> index cfebc6495..eaf9a4686 100644
> --- a/daemon/device-name-translation.c
> +++ b/daemon/device-name-translation.c
> @@ -251,9 +251,28 @@ device_name_translation (const char *device)
> char *
> reverse_device_name_translation (const char *device)
> {
> + const char *original_device = device;
> char *ret = NULL;
> size_t i;
>
> + const char *prefix = "";
> + const char *suffix = "";
> + bool btrfsvol = STRPREFIX (device, "btrfsvol:");
> + if (btrfsvol) {
> + prefix = "btrfsvol:";
> +
> + const char *device_start = device + strlen (prefix);
> + const char *device_end = strchr (device_start + strlen ("/dev/"), '/');
> + device = strndup(device_start, device_end - device_start);
> + if (device == NULL) {
> + perror ("strndup");
> + return NULL;
> + }
> +
> + suffix = device_end;
> +
> + }
> +
> /* Look it up in the cache, and if found return the canonical name.
> * If not found return a copy of the original string.
> */
> @@ -265,13 +284,19 @@ reverse_device_name_translation (const char *device)
> char drv[16];
>
> guestfs_int_drive_name (i, drv);
> - if (asprintf (&ret, "/dev/sd%s%s", drv, &device[len]) == -1) {
> + if (asprintf (&ret, "%s/dev/sd%s%s%s", prefix, drv, &device[len],
> suffix) == -1) {
> reply_with_perror ("asprintf");
> + if (btrfsvol)
> + free (device);
> return NULL;
> }
> break;
> }
> }
> + if (btrfsvol) {
> + free (device);
> + device = original_device;
> + }
>
> if (ret == NULL) {
> ret = strdup (device);
> --
> 2.52.0.460.gd25c4c69ec-goog
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
virt-p2v converts physical machines to virtual machines. Boot with a
live CD or over the network (PXE) and turn machines into KVM guests.
http://libguestfs.org/virt-v2v
>From 6d7f7d50071867f01df6181901b8f2f3fa194d14 Mon Sep 17 00:00:00 2001
From: "Richard W.M. Jones" <[email protected]>
Date: Wed, 3 Dec 2025 11:15:39 +0000
Subject: [PATCH] daemon/device-name-translation.c: Fix btrfs volume reverse
translation
Devices associated with btrfs volumes are not reverse-translated
(e.g., btrfsvol:/dev/sdX to sdY).
Forward translation occurs, creating a path mismatch. This causes
errors in subsequent btrfs commands.
Thanks: Arye Yurkovsky
---
daemon/device-name-translation.c | 32 ++++++++++++++++++++++++++++++++
1 file changed, 32 insertions(+)
diff --git a/daemon/device-name-translation.c b/daemon/device-name-translation.c
index cfebc6495..28fd5fc4b 100644
--- a/daemon/device-name-translation.c
+++ b/daemon/device-name-translation.c
@@ -248,12 +248,17 @@ device_name_translation (const char *device)
return NULL;
}
+static char *reverse_btrfsvol (const char *device);
+
char *
reverse_device_name_translation (const char *device)
{
char *ret = NULL;
size_t i;
+ if (STRPREFIX (device, "btrfsvol:"))
+ return reverse_btrfsvol (device);
+
/* Look it up in the cache, and if found return the canonical name.
* If not found return a copy of the original string.
*/
@@ -287,3 +292,30 @@ reverse_device_name_translation (const char *device)
return ret;
}
+
+/* btrfsvol:/dev/sdX also needs reversing. */
+static char *
+reverse_btrfsvol (const char *device)
+{
+ const char prefix[] = "btrfsvol:";
+ const char *device_start, *device_end;
+ CLEANUP_FREE char *device_name = NULL;
+ CLEANUP_FREE char *reversed_device = NULL;
+ char *ret;
+
+ device_start = device + strlen (prefix);
+ device_end = strchr (device_start + strlen ("/dev/"), '/');
+ device_name = strndup (device_start, device_end - device_start);
+
+ reversed_device = reverse_device_name_translation (device_name);
+ if (reversed_device == NULL)
+ return NULL;
+
+ /* Construct the final btrfsvol: and return it, caller frees. */
+ if (asprintf (&ret, "%s%s%s", prefix, reversed_device, device_end) == -1) {
+ reply_with_perror ("asprintf");
+ return NULL;
+ }
+
+ return ret;
+}
--
2.51.1
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