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 <ja...@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);