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Add btrfs-list for listing subvolumes

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Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason 2010-02-28 15:29:47 -05:00
parent ab8fb4c995
commit 4ff9e2af17
4 changed files with 541 additions and 1 deletions
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5
Makefile
View File

@ -17,7 +17,7 @@ bindir = $(prefix)/bin
LIBS=-luuid
progs = btrfsctl mkfs.btrfs btrfs-debug-tree btrfs-show btrfs-vol btrfsck \
btrfs-map-logical
btrfs-map-logical btrfs-list
# make C=1 to enable sparse
ifdef C
@ -36,6 +36,9 @@ all: version $(progs) manpages
version:
bash version.sh
btrfs-list: $(objects) btrfs-list.o
gcc $(CFLAGS) -o btrfs-list btrfs-list.o $(objects) $(LDFLAGS) $(LIBS)
btrfsctl: $(objects) btrfsctl.o
gcc $(CFLAGS) -o btrfsctl btrfsctl.o $(objects) $(LDFLAGS) $(LIBS)

466
btrfs-list.c Normal file
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@ -0,0 +1,466 @@
/*
* Copyright (C) 2010 Oracle. All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License v2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 021110-1307, USA.
*/
#ifndef __CHECKER__
#include <sys/ioctl.h>
#include <sys/mount.h>
#include "ioctl.h"
#endif
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <dirent.h>
#include <libgen.h>
#include "kerncompat.h"
#include "ctree.h"
#include "transaction.h"
#include "utils.h"
#include "version.h"
/* we store all the roots we find in an rbtree so that we can
* search for them later.
*/
struct root_lookup {
struct rb_root root;
};
/*
* one of these for each root we find.
*/
struct root_info {
struct rb_node rb_node;
/* this root's id */
u64 root_id;
/* the id of the root that references this one */
u64 ref_tree;
/* the dir id we're in from ref_tree */
u64 dir_id;
/* path from the subvol we live in to this root, including the
* root's name. This is null until we do the extra lookup ioctl.
*/
char *path;
/* the name of this root in the directory it lives in */
char name[];
};
void root_lookup_init(struct root_lookup *tree)
{
tree->root.rb_node = NULL;
}
static int comp_entry(struct root_info *entry, u64 root_id, u64 ref_tree)
{
if (entry->root_id > root_id)
return 1;
if (entry->root_id < root_id)
return -1;
if (entry->ref_tree > ref_tree)
return 1;
if (entry->ref_tree < ref_tree)
return -1;
return 0;
}
/*
* insert a new root into the tree. returns the existing root entry
* if one is already there. Both root_id and ref_tree are used
* as the key
*/
static struct rb_node *tree_insert(struct rb_root *root, u64 root_id,
u64 ref_tree, struct rb_node *node)
{
struct rb_node ** p = &root->rb_node;
struct rb_node * parent = NULL;
struct root_info *entry;
int comp;
while(*p) {
parent = *p;
entry = rb_entry(parent, struct root_info, rb_node);
comp = comp_entry(entry, root_id, ref_tree);
if (comp < 0)
p = &(*p)->rb_left;
else if (comp > 0)
p = &(*p)->rb_right;
else
return parent;
}
entry = rb_entry(parent, struct root_info, rb_node);
rb_link_node(node, parent, p);
rb_insert_color(node, root);
return NULL;
}
/*
* find a given root id in the tree. We return the smallest one,
* rb_next can be used to move forward looking for more if required
*/
static struct root_info *tree_search(struct rb_root *root, u64 root_id)
{
struct rb_node * n = root->rb_node;
struct root_info *entry;
while(n) {
entry = rb_entry(n, struct root_info, rb_node);
if (entry->root_id < root_id)
n = n->rb_left;
else if (entry->root_id > root_id)
n = n->rb_right;
else {
struct root_info *prev;
struct rb_node *prev_n;
while (1) {
prev_n = rb_prev(n);
if (!prev_n)
break;
prev = rb_entry(prev_n, struct root_info,
rb_node);
if (prev->root_id != root_id)
break;
entry = prev;
n = prev_n;
}
return entry;
}
}
return NULL;
}
/*
* helper to open either a file or directory so that
* we can run ioctls on it.
*/
static int open_file_or_dir(const char *fname)
{
int ret;
struct stat st;
DIR *dirstream;
int fd;
ret = stat(fname, &st);
if (ret < 0) {
perror("stat:");
exit(1);
}
if (S_ISDIR(st.st_mode)) {
dirstream = opendir(fname);
if (!dirstream) {
perror("opendir");
exit(1);
}
fd = dirfd(dirstream);
} else {
fd = open(fname, O_RDWR);
}
if (fd < 0) {
perror("open");
exit(1);
}
return fd;
}
/*
* this allocates a new root in the lookup tree.
*
* root_id should be the object id of the root
*
* ref_tree is the objectid of the referring root.
*
* dir_id is the directory in ref_tree where this root_id can be found.
*
* name is the name of root_id in that directory
*
* name_len is the length of name
*/
static int add_root(struct root_lookup *root_lookup,
u64 root_id, u64 ref_tree, u64 dir_id, char *name,
int name_len)
{
struct root_info *ri;
struct rb_node *ret;
ri = malloc(sizeof(*ri) + name_len);
if (!ri) {
printf("memory allocation failed\n");
exit(1);
}
ri->path = NULL;
ri->dir_id = dir_id;
ri->root_id = root_id;
ri->ref_tree = ref_tree;
strncpy(ri->name, name, name_len);
ret = tree_insert(&root_lookup->root, root_id, ref_tree, &ri->rb_node);
if (ret) {
printf("failed to insert tree %llu\n", (unsigned long long)root_id);
exit(1);
}
return 0;
}
/*
* for a given root_info, search through the root_lookup tree to construct
* the full path name to it.
*
* This can't be called until all the root_info->path fields are filled
* in by lookup_ino_path
*/
static int resolve_root(struct root_lookup *rl, struct root_info *ri)
{
u64 top_id;
char *full_path = NULL;
int len = 0;
struct root_info *found;
/*
* we go backwards from the root_info object and add pathnames
* from parent directories as we go.
*/
found = ri;
while (1) {
char *tmp;
u64 next;
int add_len = strlen(found->path);
/* room for / and for null */
tmp = malloc(add_len + 2 + len);
if (full_path) {
memcpy(tmp + add_len + 1, full_path, len);
tmp[add_len] = '/';
memcpy(tmp, found->path, add_len);
tmp [add_len + len + 1] = '\0';
free(full_path);
full_path = tmp;
len += add_len + 1;
} else {
full_path = strdup(found->path);
len = add_len;
}
next = found->ref_tree;
/* if the ref_tree refers to ourselves, we're at the top */
if (next == found->root_id) {
top_id = next;
break;
}
/*
* if the ref_tree wasn't in our tree of roots, we're
* at the top
*/
found = tree_search(&rl->root, next);
if (!found) {
top_id = next;
break;
}
}
printf("ID %llu top level %llu path %s\n", ri->root_id, top_id,
full_path);
free(full_path);
return 0;
}
/*
* for a single root_info, ask the kernel to give us a path name
* inside it's ref_root for the dir_id where it lives.
*
* This fills in root_info->path with the path to the directory and and
* appends this root's name.
*/
static int lookup_ino_path(int fd, struct root_info *ri)
{
struct btrfs_ioctl_ino_lookup_args args;
int ret;
if (ri->path)
return 0;
args.treeid = ri->ref_tree;
args.objectid = ri->dir_id;
args.name[0] = '\0';
ret = ioctl(fd, BTRFS_IOC_INO_LOOKUP, &args);
if (ret) {
fprintf(stderr, "Failed to lookup path for root %llu\n",
(unsigned long long)ri->ref_tree);
exit(1);
}
if (args.name[0]) {
/*
* we're in a subdirectory of ref_tree, the kernel ioctl
* puts a / in there for us
*/
ri->path = malloc(strlen(ri->name) + strlen(args.name) + 1);
if (!ri->path) {
perror("malloc failed");
exit(1);
}
strcpy(ri->path, args.name);
strcat(ri->path, ri->name);
} else {
/* we're at the root of ref_tree */
ri->path = strdup(ri->name);
if (!ri->path) {
perror("strdup failed");
exit(1);
}
}
return 0;
}
static int list_subvols(int fd)
{
struct root_lookup root_lookup;
struct rb_node *n;
int ret;
struct btrfs_ioctl_search_args args;
struct btrfs_ioctl_search_key *sk = &args.key;
struct btrfs_ioctl_search_header *sh;
struct btrfs_root_ref *ref;
unsigned long off = 0;
int name_len;
char *name;
u64 dir_id;
int i;
root_lookup_init(&root_lookup);
memset(&args, 0, sizeof(args));
/* search in the tree of tree roots */
sk->tree_id = 1;
/*
* set the min and max to backref keys. The search will
* only send back this type of key now.
*/
sk->max_type = BTRFS_ROOT_BACKREF_KEY;
sk->min_type = BTRFS_ROOT_BACKREF_KEY;
/*
* set all the other params to the max, we'll take any objectid
* and any trans
*/
sk->max_objectid = (u64)-1;
sk->max_offset = (u64)-1;
sk->max_transid = (u64)-1;
/* just a big number, doesn't matter much */
sk->nr_items = 4096;
while(1) {
ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args);
if (ret < 0) {
perror("ioctl:");
break;
}
/* the ioctl returns the number of item it found in nr_items */
if (sk->nr_items == 0)
break;
off = 0;
/*
* for each item, pull the key out of the header and then
* read the root_ref item it contains
*/
for (i = 0; i < sk->nr_items; i++) {
sh = (struct btrfs_ioctl_search_header *)(args.buf +
off);
off += sizeof(*sh);
ref = (struct btrfs_root_ref *)(args.buf + off);
name_len = btrfs_stack_root_ref_name_len(ref);
name = (char *)(ref + 1);
dir_id = btrfs_stack_root_ref_dirid(ref);
add_root(&root_lookup, sh->objectid, sh->offset,
dir_id, name, name_len);
off += sh->len;
/*
* record the mins in sk so we can make sure the
* next search doesn't repeat this root
*/
sk->min_objectid = sh->objectid;
sk->min_type = sh->type;
sk->min_offset = sh->offset;
}
sk->nr_items = 4096;
/* this iteration is done, step forward one root for the next
* ioctl
*/
if (sk->min_objectid < (u64)-1)
sk->min_objectid++;
else
break;
}
/*
* now we have an rbtree full of root_info objects, but we need to fill
* in their path names within the subvol that is referencing each one.
*/
n = rb_first(&root_lookup.root);
while (n) {
struct root_info *entry;
entry = rb_entry(n, struct root_info, rb_node);
lookup_ino_path(fd, entry);
n = rb_next(n);
}
/* now that we have all the subvol-relative paths filled in,
* we have to string the subvols together so that we can get
* a path all the way back to the FS root
*/
n = rb_last(&root_lookup.root);
while (n) {
struct root_info *entry;
entry = rb_entry(n, struct root_info, rb_node);
resolve_root(&root_lookup, entry);
n = rb_prev(n);
}
printf("%s\n", BTRFS_BUILD_VERSION);
return ret;
}
int main(int ac, char **av)
{
int fd;
if (ac != 2) {
fprintf(stderr, "usage: btrfs-list mount_point\n");
exit(1);
}
fd = open_file_or_dir(av[1]);
return list_subvols(fd);
}

4
ctree.h
View File

@ -1325,6 +1325,10 @@ BTRFS_SETGET_FUNCS(root_ref_dirid, struct btrfs_root_ref, dirid, 64);
BTRFS_SETGET_FUNCS(root_ref_sequence, struct btrfs_root_ref, sequence, 64);
BTRFS_SETGET_FUNCS(root_ref_name_len, struct btrfs_root_ref, name_len, 16);
BTRFS_SETGET_STACK_FUNCS(stack_root_ref_dirid, struct btrfs_root_ref, dirid, 64);
BTRFS_SETGET_STACK_FUNCS(stack_root_ref_sequence, struct btrfs_root_ref, sequence, 64);
BTRFS_SETGET_STACK_FUNCS(stack_root_ref_name_len, struct btrfs_root_ref, name_len, 16);
/* struct btrfs_dir_item */
BTRFS_SETGET_FUNCS(dir_data_len, struct btrfs_dir_item, data_len, 16);
BTRFS_SETGET_FUNCS(dir_type, struct btrfs_dir_item, type, 8);

67
ioctl.h
View File

@ -30,6 +30,68 @@ struct btrfs_ioctl_vol_args {
char name[BTRFS_PATH_NAME_MAX + 1];
};
struct btrfs_ioctl_search_key {
/* which root are we searching. 0 is the tree of tree roots */
__u64 tree_id;
/* keys returned will be >= min and <= max */
__u64 min_objectid;
__u64 max_objectid;
/* keys returned will be >= min and <= max */
__u64 min_offset;
__u64 max_offset;
/* max and min transids to search for */
__u64 min_transid;
__u64 max_transid;
/* keys returned will be >= min and <= max */
__u32 min_type;
__u32 max_type;
/*
* how many items did userland ask for, and how many are we
* returning
*/
__u32 nr_items;
/* align to 64 bits */
__u32 unused;
/* some extra for later */
__u64 unused1;
__u64 unused2;
__u64 unused3;
__u64 unused4;
};
struct btrfs_ioctl_search_header {
__u64 transid;
__u64 objectid;
__u64 offset;
__u32 type;
__u32 len;
};
#define BTRFS_SEARCH_ARGS_BUFSIZE (4096 - sizeof(struct btrfs_ioctl_search_key))
/*
* the buf is an array of search headers where
* each header is followed by the actual item
* the type field is expanded to 32 bits for alignment
*/
struct btrfs_ioctl_search_args {
struct btrfs_ioctl_search_key key;
char buf[BTRFS_SEARCH_ARGS_BUFSIZE];
};
#define BTRFS_INO_LOOKUP_PATH_MAX 4080
struct btrfs_ioctl_ino_lookup_args {
__u64 treeid;
__u64 objectid;
char name[BTRFS_INO_LOOKUP_PATH_MAX];
};
#define BTRFS_IOC_SNAP_CREATE _IOW(BTRFS_IOCTL_MAGIC, 1, \
struct btrfs_ioctl_vol_args)
#define BTRFS_IOC_DEFRAG _IOW(BTRFS_IOCTL_MAGIC, 2, \
@ -59,4 +121,9 @@ struct btrfs_ioctl_vol_args {
#define BTRFS_IOC_SNAP_DESTROY _IOW(BTRFS_IOCTL_MAGIC, 15, \
struct btrfs_ioctl_vol_args)
#define BTRFS_IOC_TREE_SEARCH _IOWR(BTRFS_IOCTL_MAGIC, 17, \
struct btrfs_ioctl_search_args)
#define BTRFS_IOC_INO_LOOKUP _IOWR(BTRFS_IOCTL_MAGIC, 18, \
struct btrfs_ioctl_ino_lookup_args)
#endif