Here is a patch to btrfs-progs to provide the command "subvolume last-gen":
$ sudo ./btrfs subvolume last-gen /.snaps/1h-20101102-010001
transid marker was 2808
$ sudo ./btrfs subvolume last-gen /.snaps/1h-20101102-020001/
transid marker was 2942
$
So we can do something like:
$ sudo ./btrfs subvolume find-new /.snaps/1h-20101102-020001 2808 | head -5
inode 100399 file offset 2093056 len 4096 disk start 58160975872 offset 0
gen 2901 flags NONE var/log/messages
inode 100399 file offset 2097152 len 4096 disk start 58161836032 offset 0
gen 2934 flags NONE var/log/messages
inode 100400 file offset 40960 len 4096 disk start 58162188288 offset 0 gen
2941 flags NONE var/log/secure
inode 100401 file offset 139264 len 4096 disk start 58155618304 offset 0
gen 2883 flags NONE var/log/maillog
inode 100401 file offset 143360 len 8192 disk start 58154278912 offset 0
gen 2930 flags NONE var/log/maillog
$
Otherwise, the only way I could figure out to do it was to pass a gen id
that was hopefully too big to get the transid line:
$ sudo ./btrfs subvolume find-new /.snapshots/1h-20101102-010001 \
999999999999999
transid marker was 2808
$
Unless I'm missing something...
Sean
From 0a831df42f5b64db5c2f6a80531d2c4572ba5fc4 Mon Sep 17 00:00:00 2001
From: Sean Reifschneider <j...@tummy.com>
Date: Wed, 3 Nov 2010 03:03:56 -0600
Subject: [PATCH] Adding last-gen comand.
---
btrfs-list.c | 2 +-
btrfs.c | 3 +++
btrfs_cmds.c | 29 +++++++++++++++++++++++++++++
btrfs_cmds.h | 2 ++
4 files changed, 35 insertions(+), 1 deletions(-)
diff --git a/btrfs-list.c b/btrfs-list.c
index 93766a8..7e4a282 100644
--- a/btrfs-list.c
+++ b/btrfs-list.c
@@ -310,7 +310,7 @@ static int lookup_ino_path(int fd, struct root_info *ri)
* Then we use the tree search ioctl to scan all the root items for a
* given root id and spit out the latest generation we can find
*/
-static u64 find_root_gen(int fd)
+u64 find_root_gen(int fd)
{
struct btrfs_ioctl_ino_lookup_args ino_args;
int ret;
diff --git a/btrfs.c b/btrfs.c
index 46314cf..188b451 100644
--- a/btrfs.c
+++ b/btrfs.c
@@ -64,6 +64,9 @@ static struct Command commands[] = {
{ do_find_newer, 2, "subvolume find-new", "<path> <last_gen>\n"
"List the recently modified files in a filesystem."
},
+ { do_get_latest_gen, 1, "subvolume last-gen", "<path>\n"
+ "Return the latest generation of a filesystem."
+ },
{ do_defrag, -1,
"filesystem defragment", "[-vcf] [-s start] [-l len] [-t size]
<file>|<dir> [<file>|<dir>...]\n"
"Defragment a file or a directory."
diff --git a/btrfs_cmds.c b/btrfs_cmds.c
index 8031c58..25eafb8 100644
--- a/btrfs_cmds.c
+++ b/btrfs_cmds.c
@@ -247,6 +247,35 @@ int do_defrag(int ac, char **av)
return errors + 20;
}
+int do_get_latest_gen(int argc, char **argv)
+{
+ int fd;
+ int ret;
+ char *subvol;
+ u64 max_found = 0;
+
+ subvol = argv[1];
+
+ ret = test_issubvolume(subvol);
+ if (ret < 0) {
+ fprintf(stderr, "ERROR: error accessing '%s'\n", subvol);
+ return 12;
+ }
+ if (!ret) {
+ fprintf(stderr, "ERROR: '%s' is not a subvolume\n", subvol);
+ return 13;
+ }
+
+ fd = open_file_or_dir(subvol);
+ if (fd < 0) {
+ fprintf(stderr, "ERROR: can't access '%s'\n", subvol);
+ return 12;
+ }
+ max_found = find_root_gen(fd);
+ printf("transid marker was %llu\n", (unsigned long long)max_found);
+ return 0;
+}
+
int do_find_newer(int argc, char **argv)
{
int fd;
diff --git a/btrfs_cmds.h b/btrfs_cmds.h
index 7bde191..ea4e18e 100644
--- a/btrfs_cmds.h
+++ b/btrfs_cmds.h
@@ -20,6 +20,7 @@ int do_delete_subvolume(int nargs, char **argv);
int do_create_subvol(int nargs, char **argv);
int do_fssync(int nargs, char **argv);
int do_defrag(int argc, char **argv);
+int do_get_latest_gen(int argc, char **argv);
int do_show_filesystem(int nargs, char **argv);
int do_add_volume(int nargs, char **args);
int do_balance(int nargs, char **argv);
@@ -32,3 +33,4 @@ int list_subvols(int fd);
int do_df_filesystem(int nargs, char **argv);
int find_updated_files(int fd, u64 root_id, u64 oldest_gen);
int do_find_newer(int argc, char **argv);
+u64 find_root_gen(int fd);
--
1.7.3.1
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