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authorNikolay Borisov <nborisov@suse.com>2018-10-30 16:43:26 +0200
committerDavid Sterba <dsterba@suse.com>2018-12-17 14:51:38 +0100
commitd1a63002829a4d8014de20dc141b404cc808405e (patch)
tree0734637651debfcf49ac8c20c8711a4924d131bd /fs/btrfs
parentfbc6feaec98ac0c6a615bbe9e17c5689a1a84650 (diff)
downloadlinux-d1a63002829a4d8014de20dc141b404cc808405e.tar.bz2
btrfs: add members to fs_devices to track fsid changes
In order to gracefully handle split-brain scenario during fsid change (which are very unlikely, yet possible), two more pieces of information will be necessary: 1. The highest generation number among all devices registered to a particular btrfs_fs_devices 2. A boolean flag whether a given btrfs_fs_devices was created by a device which had the FSID_CHANGING_V2 flag set. This is a preparatory patch and just introduces the variables as well as code which sets them, their actual use is going to happen in a later patch. Signed-off-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs')
-rw-r--r--fs/btrfs/volumes.c9
-rw-r--r--fs/btrfs/volumes.h5
2 files changed, 13 insertions, 1 deletions
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 032310dacf77..13bb44194c56 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -792,6 +792,8 @@ static noinline struct btrfs_device *device_list_add(const char *path,
u64 devid = btrfs_stack_device_id(&disk_super->dev_item);
bool has_metadata_uuid = (btrfs_super_incompat_flags(disk_super) &
BTRFS_FEATURE_INCOMPAT_METADATA_UUID);
+ bool fsid_change_in_progress = (btrfs_super_flags(disk_super) &
+ BTRFS_SUPER_FLAG_CHANGING_FSID_V2);
if (has_metadata_uuid)
fs_devices = find_fsid(disk_super->fsid, disk_super->metadata_uuid);
@@ -805,6 +807,8 @@ static noinline struct btrfs_device *device_list_add(const char *path,
else
fs_devices = alloc_fs_devices(disk_super->fsid, NULL);
+ fs_devices->fsid_change = fsid_change_in_progress;
+
if (IS_ERR(fs_devices))
return ERR_CAST(fs_devices);
@@ -940,8 +944,11 @@ static noinline struct btrfs_device *device_list_add(const char *path,
* it back. We need it to pick the disk with largest generation
* (as above).
*/
- if (!fs_devices->opened)
+ if (!fs_devices->opened) {
device->generation = found_transid;
+ fs_devices->latest_generation = max_t(u64, found_transid,
+ fs_devices->latest_generation);
+ }
fs_devices->total_devices = btrfs_super_num_devices(disk_super);
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index bdee4b60e0ba..1d936ce282c3 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -211,6 +211,7 @@ BTRFS_DEVICE_GETSET_FUNCS(bytes_used);
struct btrfs_fs_devices {
u8 fsid[BTRFS_FSID_SIZE]; /* FS specific uuid */
u8 metadata_uuid[BTRFS_FSID_SIZE];
+ bool fsid_change;
struct list_head fs_list;
u64 num_devices;
@@ -219,6 +220,10 @@ struct btrfs_fs_devices {
u64 missing_devices;
u64 total_rw_bytes;
u64 total_devices;
+
+ /* Highest generation number of seen devices */
+ u64 latest_generation;
+
struct block_device *latest_bdev;
/* all of the devices in the FS, protected by a mutex