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authorAlexander Block <ablock84@googlemail.com>2012-07-25 17:35:53 +0200
committerAlexander Block <ablock84@googlemail.com>2012-07-25 23:28:38 +0200
commit8ea05e3a4262b9e6871c349fa3486bcfc72ffd1a (patch)
tree893a8ff635b31caf920aaa97948e612640cbac6a /fs/btrfs/ctree.h
parent91cb916ca26feb99c78c131a1643af3d10fefd96 (diff)
Btrfs: introduce subvol uuids and times
This patch introduces uuids for subvolumes. Each subvolume has it's own uuid. In case it was snapshotted, it also contains parent_uuid. In case it was received, it also contains received_uuid. It also introduces subvolume ctime/otime/stime/rtime. The first two are comparable to the times found in inodes. otime is the origin/creation time and ctime is the change time. stime/rtime are only valid on received subvolumes. stime is the time of the subvolume when it was sent. rtime is the time of the subvolume when it was received. Additionally to the times, we have a transid for each time. They are updated at the same place as the times. btrfs receive uses stransid and rtransid to find out if a received subvolume changed in the meantime. If an older kernel mounts a filesystem with the extented fields, all fields become invalid. The next mount with a new kernel will detect this and reset the fields. Signed-off-by: Alexander Block <ablock84@googlemail.com> Reviewed-by: David Sterba <dave@jikos.cz> Reviewed-by: Arne Jansen <sensille@gmx.net> Reviewed-by: Jan Schmidt <list.btrfs@jan-o-sch.net> Reviewed-by: Alex Lyakas <alex.bolshoy.btrfs@gmail.com>
Diffstat (limited to 'fs/btrfs/ctree.h')
-rw-r--r--fs/btrfs/ctree.h47
1 files changed, 47 insertions, 0 deletions
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 8cfde9326dd6..d5f6d7458676 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -709,6 +709,36 @@ struct btrfs_root_item {
struct btrfs_disk_key drop_progress;
u8 drop_level;
u8 level;
+
+ /*
+ * The following fields appear after subvol_uuids+subvol_times
+ * were introduced.
+ */
+
+ /*
+ * This generation number is used to test if the new fields are valid
+ * and up to date while reading the root item. Everytime the root item
+ * is written out, the "generation" field is copied into this field. If
+ * anyone ever mounted the fs with an older kernel, we will have
+ * mismatching generation values here and thus must invalidate the
+ * new fields. See btrfs_update_root and btrfs_find_last_root for
+ * details.
+ * the offset of generation_v2 is also used as the start for the memset
+ * when invalidating the fields.
+ */
+ __le64 generation_v2;
+ u8 uuid[BTRFS_UUID_SIZE];
+ u8 parent_uuid[BTRFS_UUID_SIZE];
+ u8 received_uuid[BTRFS_UUID_SIZE];
+ __le64 ctransid; /* updated when an inode changes */
+ __le64 otransid; /* trans when created */
+ __le64 stransid; /* trans when sent. non-zero for received subvol */
+ __le64 rtransid; /* trans when received. non-zero for received subvol */
+ struct btrfs_timespec ctime;
+ struct btrfs_timespec otime;
+ struct btrfs_timespec stime;
+ struct btrfs_timespec rtime;
+ __le64 reserved[8]; /* for future */
} __attribute__ ((__packed__));
/*
@@ -1416,6 +1446,8 @@ struct btrfs_root {
dev_t anon_dev;
int force_cow;
+
+ spinlock_t root_times_lock;
};
struct btrfs_ioctl_defrag_range_args {
@@ -2189,6 +2221,16 @@ BTRFS_SETGET_STACK_FUNCS(root_used, struct btrfs_root_item, bytes_used, 64);
BTRFS_SETGET_STACK_FUNCS(root_limit, struct btrfs_root_item, byte_limit, 64);
BTRFS_SETGET_STACK_FUNCS(root_last_snapshot, struct btrfs_root_item,
last_snapshot, 64);
+BTRFS_SETGET_STACK_FUNCS(root_generation_v2, struct btrfs_root_item,
+ generation_v2, 64);
+BTRFS_SETGET_STACK_FUNCS(root_ctransid, struct btrfs_root_item,
+ ctransid, 64);
+BTRFS_SETGET_STACK_FUNCS(root_otransid, struct btrfs_root_item,
+ otransid, 64);
+BTRFS_SETGET_STACK_FUNCS(root_stransid, struct btrfs_root_item,
+ stransid, 64);
+BTRFS_SETGET_STACK_FUNCS(root_rtransid, struct btrfs_root_item,
+ rtransid, 64);
static inline bool btrfs_root_readonly(struct btrfs_root *root)
{
@@ -2822,6 +2864,9 @@ int __must_check btrfs_update_root(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_key *key,
struct btrfs_root_item *item);
+void btrfs_read_root_item(struct btrfs_root *root,
+ struct extent_buffer *eb, int slot,
+ struct btrfs_root_item *item);
int btrfs_find_last_root(struct btrfs_root *root, u64 objectid, struct
btrfs_root_item *item, struct btrfs_key *key);
int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid);
@@ -2829,6 +2874,8 @@ int btrfs_find_orphan_roots(struct btrfs_root *tree_root);
void btrfs_set_root_node(struct btrfs_root_item *item,
struct extent_buffer *node);
void btrfs_check_and_init_root_item(struct btrfs_root_item *item);
+void btrfs_update_root_times(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root);
/* dir-item.c */
int btrfs_insert_dir_item(struct btrfs_trans_handle *trans,