David Sterba
2013-Sep-18 16:19 UTC
[PATCH] btrfs-progs: look up the containing tree root id
Find the tree id of the containing subvolume for a given file or
directory. For subvolume return it''s own id.
$ btrfs inspect-internal rootid <path>
Signed-off-by: David Sterba <dsterba@suse.cz>
---
cmds-inspect.c | 38 ++++++++++++++++++++++++++++++++++++++
man/btrfs.8.in | 9 +++++++++
utils.c | 30 ++++++++++++++++++++++++++++++
utils.h | 2 ++
4 files changed, 79 insertions(+), 0 deletions(-)
diff --git a/cmds-inspect.c b/cmds-inspect.c
index bdebf7d..f0c8e3d 100644
--- a/cmds-inspect.c
+++ b/cmds-inspect.c
@@ -301,6 +301,43 @@ out:
return ret ? 1 : 0;
}
+static const char* const cmd_rootid_usage[] = {
+ "btrfs inspect-internal rootid <path>",
+ "Get tree ID of the containing subvolume of path.",
+ NULL
+};
+
+static int cmd_rootid(int argc, char **argv)
+{
+ int ret;
+ int fd = -1;
+ u64 rootid;
+ DIR *dirstream = NULL;
+
+ if (check_argc_exact(argc, 2))
+ usage(cmd_rootid_usage);
+
+ fd = open_file_or_dir(argv[1], &dirstream);
+ if (fd < 0) {
+ fprintf(stderr, "ERROR: can''t access
''%s''\n", argv[1]);
+ ret = -ENOENT;
+ goto out;
+ }
+
+ ret = lookup_ino_rootid(fd, &rootid);
+ if (ret) {
+ fprintf(stderr, "%s: rootid failed with ret=%d\n",
+ argv[0], ret);
+ goto out;
+ }
+
+ printf("%llu\n", (unsigned long long)rootid);
+out:
+ close_file_or_dir(fd, dirstream);
+
+ return !!ret;
+}
+
const struct cmd_group inspect_cmd_group = {
inspect_cmd_group_usage, NULL, {
{ "inode-resolve", cmd_inode_resolve, cmd_inode_resolve_usage,
@@ -309,6 +346,7 @@ const struct cmd_group inspect_cmd_group = {
cmd_logical_resolve_usage, NULL, 0 },
{ "subvolid-resolve", cmd_subvolid_resolve,
cmd_subvolid_resolve_usage, NULL, 0 },
+ { "rootid", cmd_rootid, cmd_rootid_usage, NULL, 0 },
NULL_CMD_STRUCT
}
};
diff --git a/man/btrfs.8.in b/man/btrfs.8.in
index 0b69ce2..be4a6b2 100644
--- a/man/btrfs.8.in
+++ b/man/btrfs.8.in
@@ -80,6 +80,8 @@ btrfs \- control a btrfs filesystem
.PP
\fBbtrfs\fP \fBinspect-internal subvolid-resolve\fP \fI<subvolid>\fP
\fI<path>\fP
.PP
+\fBbtrfs\fP \fBinspect-internal rootid\fP \fI<path>\fP
+.PP
.PP
\fBbtrfs\fP \fBsend\fP [-v] [-p \fI<parent>\fP] [-c
\fI<clone-src>\fP] [-f \fI<outfile>\fP] \fI<subvol>\fP
.PP
@@ -582,6 +584,13 @@ not enough to read all the resolved results. The max value
one can set is 64k.
Get file system paths for the given subvolume ID.
.TP
+\fBinspect-internal rootid\fP \fI<path>\fP
+For a given file or directory, return the containing tree root id. For a
+subvolume return it''s own tree id.
+
+The result is undefined for the so-called empty subvolumes (identified by inode
number 2).
+.TP
+
\fBsend\fP [-v] [-p \fI<parent>\fP] [-c \fI<clone-src>\fP] [-f
\fI<outfile>\fP] \fI<subvol>\fP
Send the subvolume to stdout.
Sends the subvolume specified by \fI<subvol>\fR to stdout.
diff --git a/utils.c b/utils.c
index 5fa193b..8aecc4a 100644
--- a/utils.c
+++ b/utils.c
@@ -1975,3 +1975,33 @@ int ask_user(char *question)
(answer = strtok_r(buf, " \t\n\r", &saveptr)) &&
(!strcasecmp(answer, "yes") || !strcasecmp(answer,
"y"));
}
+
+/*
+ * For a given:
+ * - file or directory return the containing tree root id
+ * - subvolume return it''s own tree id
+ * - BTRFS_EMPTY_SUBVOL_DIR_OBJECTID (directory with ino == 2) the result is
+ * undefined and function returns -1
+ */
+int lookup_ino_rootid(int fd, u64 *rootid)
+{
+ struct btrfs_ioctl_ino_lookup_args args;
+ int ret;
+ int e;
+
+ memset(&args, 0, sizeof(args));
+ args.treeid = 0;
+ args.objectid = BTRFS_FIRST_FREE_OBJECTID;
+
+ ret = ioctl(fd, BTRFS_IOC_INO_LOOKUP, &args);
+ e = errno;
+ if (ret) {
+ fprintf(stderr, "ERROR: Failed to lookup root id - %s\n",
+ strerror(e));
+ return ret;
+ }
+
+ *rootid = args.treeid;
+
+ return 0;
+}
diff --git a/utils.h b/utils.h
index fdef3f0..19f028f 100644
--- a/utils.h
+++ b/utils.h
@@ -81,4 +81,6 @@ int is_vol_small(char *file);
int csum_tree_block(struct btrfs_root *root, struct extent_buffer *buf,
int verify);
int ask_user(char *question);
+int lookup_ino_rootid(int fd, u64 *rootid);
+
#endif
--
1.7.9
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