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authorAnand Jain <anand.jain@oracle.com>2014-07-03 14:22:06 +0400
committerChris Mason <clm@fb.com>2014-08-19 19:36:30 +0400
commit77bdae4d136e167bab028cbec58b988f91cf73c0 (patch)
tree3c2477baa2f64cc00db475efc2f52d399f1a4beb /fs/btrfs/volumes.c
parentb96de000bc8bc9688b3a2abea4332bd57648a49f (diff)
downloadlinux-77bdae4d136e167bab028cbec58b988f91cf73c0.tar.xz
btrfs: check generation as replace duplicates devid+uuid
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>
Diffstat (limited to 'fs/btrfs/volumes.c')
-rw-r--r--fs/btrfs/volumes.c22
1 files changed, 21 insertions, 1 deletions
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 7c538f65214b..5700ab03e84b 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;