[PATCH] btrfs-progs: Check mount status of multidevice filesystems

Andi Drebes
2009-11-14T18:44:51Z

Some programs like btrfsck should not be run on a mounted filesystem.
This patch adds a check in btrfs_open_devices() for the mount status
of every device belonging to the filesystem. The function check_mount()
gets improved support for loopback devices. It now detects if the
program is run on the file that is being used by the loopback device.

Signed-off-by: Andi Drebes <lists-receive@programmierforen.de>
---
diff --git a/btrfs-map-logical.c b/btrfs-map-logical.c
index a109c6a..1e0ef9f 100644
--- a/btrfs-map-logical.c
+++ b/btrfs-map-logical.c
@@ -169,7 +169,7 @@ int main(int ac, char **av)
radix_tree_init();
cache_tree_init(&root_cache);

- root = open_ctree(dev, 0, 0);
+ root = open_ctree(dev, 0, 0, 0);
if (!root) {
fprintf(stderr, "Open ctree failed\n");
exit(1);
diff --git a/btrfsck.c b/btrfsck.c
index 73f1836..1434791 100644
--- a/btrfsck.c
+++ b/btrfsck.c
@@ -2821,7 +2821,7 @@ int main(int ac, char **av)

radix_tree_init();
cache_tree_init(&root_cache);
- root = open_ctree(av[1], 0, 0);
+ root = open_ctree(av[1], 0, 0, 1);

if (root == NULL)
return 1;
diff --git a/debug-tree.c b/debug-tree.c
index 1d47519..a8e85f4 100644
--- a/debug-tree.c
+++ b/debug-tree.c
@@ -137,7 +137,7 @@ int main(int ac, char **av)
if (ac != 1)
print_usage();

- root = open_ctree(av[optind], 0, 0);
+ root = open_ctree(av[optind], 0, 0, 0);
if (!root) {
fprintf(stderr, "unable to open %s\n", av[optind]);
exit(1);
diff --git a/disk-io.c b/disk-io.c
index addebe1..f8e623b 100644
--- a/disk-io.c
+++ b/disk-io.c
@@ -570,7 +570,7 @@ struct btrfs_root *btrfs_read_fs_root(struct btrfs_fs_info *fs_info,
return root;
}

-struct btrfs_root *open_ctree(const char *filename, u64 sb_bytenr, int writes)
+struct btrfs_root *open_ctree(const char *filename, u64 sb_bytenr, int writes, int check_mount)
{
int fp;
struct btrfs_root *root;
@@ -584,14 +584,14 @@ struct btrfs_root *open_ctree(const char *filename, u64 sb_bytenr, int writes)
fprintf (stderr, "Could not open %s\n", filename);
return NULL;
}
- root = open_ctree_fd(fp, filename, sb_bytenr, writes);
+ root = open_ctree_fd(fp, filename, sb_bytenr, writes, check_mount);
close(fp);

return root;
}

struct btrfs_root *open_ctree_fd(int fp, const char *path, u64 sb_bytenr,
- int writes)
+ int writes, int check_mount)
{
u32 sectorsize;
u32 nodesize;
@@ -657,9 +657,9 @@ struct btrfs_root *open_ctree_fd(int fp, const char *path, u64 sb_bytenr,
fs_info, BTRFS_ROOT_TREE_OBJECTID);

if (writes)
- ret = btrfs_open_devices(fs_devices, O_RDWR);
+ ret = btrfs_open_devices(fs_devices, O_RDWR, check_mount);
else
- ret = btrfs_open_devices(fs_devices, O_RDONLY);
+ ret = btrfs_open_devices(fs_devices, O_RDONLY, check_mount);
BUG_ON(ret);

fs_info->super_bytenr = sb_bytenr;
@@ -725,7 +725,7 @@ struct btrfs_root *open_ctree_fd(int fp, const char *path, u64 sb_bytenr,
BTRFS_UUID_SIZE);

if (!(btrfs_super_flags(disk_super) & BTRFS_SUPER_FLAG_METADUMP)) {
- ret = btrfs_read_chunk_tree(chunk_root);
+ ret = btrfs_read_chunk_tree(chunk_root, check_mount);
BUG_ON(ret);
}

diff --git a/disk-io.h b/disk-io.h
index 49e5692..1d6519e 100644
--- a/disk-io.h
+++ b/disk-io.h
@@ -43,9 +43,9 @@ struct extent_buffer *btrfs_find_create_tree_block(struct btrfs_root *root,
u64 bytenr, u32 blocksize);
int clean_tree_block(struct btrfs_trans_handle *trans,
struct btrfs_root *root, struct extent_buffer *buf);
-struct btrfs_root *open_ctree(const char *filename, u64 sb_bytenr, int writes);
+struct btrfs_root *open_ctree(const char *filename, u64 sb_bytenr, int writes, int check_mount);
struct btrfs_root *open_ctree_fd(int fp, const char *path, u64 sb_bytenr,
- int writes);
+ int writes, int check_mount);
int close_ctree(struct btrfs_root *root);
int write_ctree_super(struct btrfs_trans_handle *trans,
struct btrfs_root *root);
diff --git a/kerncompat.h b/kerncompat.h
index e4c8ce0..46236cd 100644
--- a/kerncompat.h
+++ b/kerncompat.h
@@ -42,7 +42,11 @@
#define GFP_NOFS 0
#define __read_mostly
#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+
+#ifndef ULONG_MAX
#define ULONG_MAX (~0UL)
+#endif
+
#define BUG() abort()
#ifdef __CHECKER__
#define __force __attribute__((force))
diff --git a/mkfs.c b/mkfs.c
index 2e99b95..f226661 100644
--- a/mkfs.c
+++ b/mkfs.c
@@ -456,7 +456,7 @@ int main(int ac, char **av)
fprintf(stderr, "error during mkfs %d\n", ret);
exit(1);
}
- root = open_ctree(file, 0, O_RDWR);
+ root = open_ctree(file, 0, O_RDWR, 1);
root->fs_info->alloc_start = alloc_start;

ret = make_root_dir(root);
diff --git a/utils.c b/utils.c
index 2f4c6e1..60c3f24 100644
--- a/utils.c
+++ b/utils.c
@@ -31,6 +31,8 @@
#include <fcntl.h>
#include <unistd.h>
#include <mntent.h>
+#include <linux/loop.h>
+#include <limits.h>
#include "kerncompat.h"
#include "radix-tree.h"
#include "ctree.h"
@@ -586,46 +588,105 @@ error:
return ret;
}

+int is_loop_device (const char *device) {
+ struct stat statbuf;
+
+ if(stat(device, &statbuf) < 0)
+ return -errno;
+
+ return (S_ISBLK(statbuf.st_mode) &&
+ major(statbuf.st_rdev) == LOOP_MAJOR);
+}
+
+int is_same_blk_file(const char* a, const char* b)
+{
+ struct stat st_buf_a, st_buf_b;
+ char real_a[PATH_MAX];
+ char real_b[PATH_MAX];
+
+ if(!realpath(a, real_a) ||
+ !realpath(b, real_b))
+ {
+ return -errno;
+ }
+
+ /* Identical path? */
+ if(strcmp(real_a, real_b) == 0)
+ return 1;
+
+ if(stat(a, &st_buf_a) < 0 ||
+ stat(b, &st_buf_b) < 0)
+ {
+ return -errno;
+ }
+
+ /* Same blockdevice? */
+ if(S_ISBLK(st_buf_a.st_mode) &&
+ S_ISBLK(st_buf_b.st_mode) &&
+ st_buf_a.st_rdev == st_buf_b.st_rdev)
+ {
+ return 1;
+ }
+
+ /* Hardlink? */
+ if (st_buf_a.st_dev == st_buf_b.st_dev &&
+ st_buf_a.st_ino == st_buf_b.st_ino)
+ {
+ return 1;
+ }
+
+ return 0;
+}
+
/*
* returns 1 if the device was mounted, < 0 on error or 0 if everything
- * is safe to continue. TODO, this should also scan multi-device filesystems
+ * is safe to continue.
*/
int check_mounted(char *file)
{
struct mntent *mnt;
- struct stat st_buf;
- dev_t file_dev = 0;
- dev_t file_rdev = 0;
- ino_t file_ino = 0;
FILE *f;
int ret = 0;

- if ((f = setmntent ("/proc/mounts", "r")) == NULL)
- return -errno;
+ int loop_fd;
+ struct loop_info loopinfo;

- if (stat(file, &st_buf) < 0) {
+ if ((f = setmntent ("/proc/mounts", "r")) == NULL)
return -errno;
- } else {
- if (S_ISBLK(st_buf.st_mode)) {
- file_rdev = st_buf.st_rdev;
- } else {
- file_dev = st_buf.st_dev;
- file_ino = st_buf.st_ino;
- }
- }

while ((mnt = getmntent (f)) != NULL) {
- if (strcmp(file, mnt->mnt_fsname) == 0)
- break;
+ /* Only check btrfs filesystems */
+ if(strcmp(mnt->mnt_type, "btrfs") != 0)
+ continue;

- if (stat(mnt->mnt_fsname, &st_buf) == 0) {
- if (S_ISBLK(st_buf.st_mode)) {
- if (file_rdev && (file_rdev == st_buf.st_rdev))
- break;
- } else if (file_dev && ((file_dev == st_buf.st_dev) &&
- (file_ino == st_buf.st_ino))) {
+ ret = is_loop_device(mnt->mnt_fsname);
+
+ if(ret < 0)
+ goto out_err;
+
+ if(ret) {
+ /* Current entry is a loop device */
+ if ((loop_fd = open(mnt->mnt_fsname, O_RDONLY)) < 0) {
+ ret = -errno;
+ goto out_err;
+ }
+
+ /* Get loop device info and check */
+ if (ioctl(loop_fd, LOOP_GET_STATUS, &loopinfo) == 0) {
+ ret = is_same_blk_file(file, loopinfo.lo_name);
+
+ if(ret < 0)
+ goto out_err;
+ else if(ret)
break;
+ } else {
+ ret = -errno;
+ goto out_err;
}
+ } else {
+ /* normal block device */
+ if(is_same_blk_file(file, mnt->mnt_fsname) > 0)
+ break;
}
}

@@ -634,6 +695,7 @@ int check_mounted(char *file)
ret = 1;
}

+out_err:
endmntent (f);
return ret;
}
diff --git a/utils.h b/utils.h
index 7ff542b..695686b 100644
--- a/utils.h
+++ b/utils.h
@@ -19,6 +19,12 @@
#ifndef __UTILS__
#define __UTILS__

+#define LOOP_MAJOR 7
+
+#ifndef major
+#define major(dev) ((dev) >> 8)
+#endif
+
#define BTRFS_MKFS_SYSTEM_GROUP_SIZE (4 * 1024 * 1024)

int make_btrfs(int fd, const char *device, const char *label,
diff --git a/volumes.c b/volumes.c
index 7671855..467f552 100644
--- a/volumes.c
+++ b/volumes.c
@@ -29,6 +29,7 @@
#include "transaction.h"
#include "print-tree.h"
#include "volumes.h"
+#include "utils.h"

struct stripe {
struct btrfs_device *dev;
@@ -164,7 +165,7 @@ again:
return 0;
}

-int btrfs_open_devices(struct btrfs_fs_devices *fs_devices, int flags)
+int btrfs_open_devices(struct btrfs_fs_devices *fs_devices, int flags, int check_mount)
{
int fd;
struct list_head *head = &fs_devices->devices;
@@ -175,6 +176,19 @@ int btrfs_open_devices(struct btrfs_fs_devices *fs_devices, int flags)
list_for_each(cur, head) {
device = list_entry(cur, struct btrfs_device, dev_list);

+ if(check_mount) {
+ ret = check_mounted(device->name);
+ if (ret < 0) {
+ fprintf(stderr, "error checking %s mount status\n", device->name);
+ goto fail;
+ }
+ if (ret == 1) {
+ fprintf(stderr, "Error: %s is currently mounted.\n", device->name);
+ ret = -EBUSY;
+ goto fail;
+ }
+ }
+
fd = open(device->name, flags);
if (fd < 0) {
ret = -errno;
@@ -1240,7 +1254,7 @@ static int fill_device_from_item(struct extent_buffer *leaf,
return 0;
}

-static int open_seed_devices(struct btrfs_root *root, u8 *fsid)
+static int open_seed_devices(struct btrfs_root *root, u8 *fsid, int check_mount)
{
struct btrfs_fs_devices *fs_devices;
int ret;
@@ -1260,7 +1274,7 @@ static int open_seed_devices(struct btrfs_root *root, u8 *fsid)
goto out;
}

- ret = btrfs_open_devices(fs_devices, O_RDONLY);
+ ret = btrfs_open_devices(fs_devices, O_RDONLY, check_mount);
if (ret)
goto out;

@@ -1272,7 +1286,8 @@ out:

static int read_one_dev(struct btrfs_root *root,
struct extent_buffer *leaf,
- struct btrfs_dev_item *dev_item)
+ struct btrfs_dev_item *dev_item,
+ int check_mount)
{
struct btrfs_device *device;
u64 devid;
@@ -1289,7 +1304,7 @@ static int read_one_dev(struct btrfs_root *root,
BTRFS_UUID_SIZE);

if (memcmp(fs_uuid, root->fs_info->fsid, BTRFS_UUID_SIZE)) {
- ret = open_seed_devices(root, fs_uuid);
+ ret = open_seed_devices(root, fs_uuid, check_mount);
if (ret)
return ret;
}
@@ -1311,13 +1326,13 @@ static int read_one_dev(struct btrfs_root *root,
return ret;
}

-int btrfs_read_super_device(struct btrfs_root *root, struct extent_buffer *buf)
+int btrfs_read_super_device(struct btrfs_root *root, struct extent_buffer *buf, int check_mount)
{
struct btrfs_dev_item *dev_item;

dev_item = (struct btrfs_dev_item *)offsetof(struct btrfs_super_block,
dev_item);
- return read_one_dev(root, buf, dev_item);
+ return read_one_dev(root, buf, dev_item, check_mount);
}

int btrfs_read_sys_array(struct btrfs_root *root)
@@ -1378,7 +1393,7 @@ int btrfs_read_sys_array(struct btrfs_root *root)
return 0;
}

-int btrfs_read_chunk_tree(struct btrfs_root *root)
+int btrfs_read_chunk_tree(struct btrfs_root *root, int check_mount)
{
struct btrfs_path *path;
struct extent_buffer *leaf;
@@ -1421,7 +1436,7 @@ again:
struct btrfs_dev_item *dev_item;
dev_item = btrfs_item_ptr(leaf, slot,
struct btrfs_dev_item);
- ret = read_one_dev(root, leaf, dev_item);
+ ret = read_one_dev(root, leaf, dev_item, check_mount);
BUG_ON(ret);
}
} else if (found_key.type == BTRFS_CHUNK_ITEM_KEY) {
diff --git a/volumes.h b/volumes.h
index bb78751..baf12ff 100644
--- a/volumes.h
+++ b/volumes.h
@@ -103,16 +103,16 @@ int btrfs_rmap_block(struct btrfs_mapping_tree *map_tree,
u64 chunk_start, u64 physical, u64 devid,
u64 **logical, int *naddrs, int *stripe_len);
int btrfs_read_sys_array(struct btrfs_root *root);
-int btrfs_read_chunk_tree(struct btrfs_root *root);
+int btrfs_read_chunk_tree(struct btrfs_root *root, int check_mount);
int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
struct btrfs_root *extent_root, u64 *start,
u64 *num_bytes, u64 type);
-int btrfs_read_super_device(struct btrfs_root *root, struct extent_buffer *buf);
+int btrfs_read_super_device(struct btrfs_root *root, struct extent_buffer *buf, int check_mount);
int btrfs_add_device(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_device *device);
int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
- int flags);
+ int flags, int check_mount);
int btrfs_close_devices(struct btrfs_fs_devices *fs_devices);
int btrfs_add_device(struct btrfs_trans_handle *trans,
struct btrfs_root *root,