[PATCH 2/2] btrfs: sysfs add devinfo/fsid to retrieve fsid from the device
From: Anand Jain <hidden>
Date: 2021-10-19 00:22:53
Subsystem:
btrfs file system, filesystems (vfs and infrastructure), the rest · Maintainers:
Chris Mason, David Sterba, Alexander Viro, Christian Brauner, Linus Torvalds
In the case of the seed device, the fsid can be different from the mounted sprout fsid. The userland has to read the device superblock to know the fsid but, that idea fails if the device is missing. So add a sysfs interface devinfo/<devid>/fsid to show the fsid of the device. For example: $ cd /sys/fs/btrfs/b10b02a5-f9de-4276-b9e8-2bfd09a578a8 $ cat devinfo/1/fsid c44d771f-639d-4df3-99ec-5bc7ad2af93b $ cat devinfo/3/fsid b10b02a5-f9de-4276-b9e8-2bfd09a578a8 Signed-off-by: Anand Jain <redacted> --- fs/btrfs/sysfs.c | 11 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index c0ea7269ff57..c10fc39cb677 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c@@ -1538,6 +1538,16 @@ static ssize_t btrfs_devinfo_writeable_show(struct kobject *kobj, } BTRFS_ATTR(devid, writeable, btrfs_devinfo_writeable_show); +static ssize_t btrfs_devinfo_fsid_show(struct kobject *kobj, + struct kobj_attribute *a, char *buf) +{ + struct btrfs_device *device = container_of(kobj, struct btrfs_device, + devid_kobj); + + return sysfs_emit(buf, "%pU\n", device->fs_devices->fsid); +} +BTRFS_ATTR(devid, fsid, btrfs_devinfo_fsid_show); + static ssize_t btrfs_devinfo_error_stats_show(struct kobject *kobj, struct kobj_attribute *a, char *buf) {
@@ -1578,6 +1588,7 @@ static struct attribute *devid_attrs[] = { BTRFS_ATTR_PTR(devid, replace_target), BTRFS_ATTR_PTR(devid, scrub_speed_max), BTRFS_ATTR_PTR(devid, writeable), + BTRFS_ATTR_PTR(devid, fsid), NULL }; ATTRIBUTE_GROUPS(devid);
--
2.31.1