btrfs: check generation as replace duplicates devid+uuid (77bdae4d) · Commits · e / devices / android_kernel_oneplus_sm7250

When FS in unmounted we need to check generation number as well since devid+uuid combination could match with the missing replaced disk when it reappears, and without this patch it might pair with the replaced disk again. device_list_add() function is called in the following threads, mount device option mount argument ioctl BTRFS_IOC_SCAN_DEV (btrfs dev scan) ioctl BTRFS_IOC_DEVICES_READY (btrfs dev ready <dev>) they have been unit tested to work fine with this patch. If the user knows what he is doing and really want to pair with replaced disk (which is not a standard operation), then he should first clear the kernel btrfs device list in the memory by doing the module unload/load and followed with the mount -o device option. Signed-off-by:

Anand Jain <anand.jain@oracle.com> Signed-off-by:

Wang Shilong <wangsl.fnst@cn.fujitsu.com> Signed-off-by:

Miao Xie <miaox@cn.fujitsu.com> Signed-off-by:

Chris Mason <clm@fb.com>

fs/btrfs/volumes.c

+21 −1

Original line number	Diff line number	Diff line
		@@ -532,8 +532,19 @@ static noinline int device_list_add(const char *path,
		* As of now don't allow update to btrfs_fs_device through
		* the btrfs dev scan cli, after FS has been mounted.
		*/
		if (fs_devices->opened)
		if (fs_devices->opened) {
		return -EBUSY;
		} else {
		/*
		* That is if the FS is _not_ mounted and if you
		* are here, that means there is more than one
		* disk with same uuid and devid.We keep the one
		* with larger generation number or the last-in if
		* generation are equal.
		*/
		if (found_transid < device->generation)
		return -EEXIST;
		}

		name = rcu_string_strdup(path, GFP_NOFS);
		if (!name)
		@@ -546,6 +557,15 @@ static noinline int device_list_add(const char *path,
		}
		}

		/*
		* Unmount does not free the btrfs_device struct but would zero
		* generation along with most of the other members. So just update
		* it back. We need it to pick the disk with largest generation
		* (as above).
		*/
		if (!fs_devices->opened)
		device->generation = found_transid;

		if (found_transid > fs_devices->latest_trans) {
		fs_devices->latest_devid = devid;
		fs_devices->latest_trans = found_transid;