From: Anand Jain <anand.jain@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Wang Shilong <wangsl.fnst@xxxxxxxxxxxxxx>
Signed-off-by: Miao Xie <miaox@xxxxxxxxxxxxxx>
---
Changelog v1->v2:
- Fix the over-80-charactor problem and unreasonable error number
---
fs/btrfs/volumes.c | 22 +++++++++++++++++++++-
1 file changed, 21 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 16e71a1..1891541 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -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;
--
1.9.3
--
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