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Btrfs-progs: replace find_mount_root from send code 

find_mount_root had the problem that it tried to conclude from a file system
path to a mount point, taking the fsid as an indicator. This only works if
no two subvolumes (sharing the same btrfs fsid) are mounted in the same
hierarchy.

Now instead, we're parsing /etc/mtab and look for the longest match.

Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
This commit is contained in:
Jan Schmidt 2012-08-20 13:40:18 +02:00
parent 043a63924c
commit f99b1f1a63
1 changed files with 21 additions and 67 deletions
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90
cmds-send.c
View File

@ -28,6 +28,7 @@
#include <sys/types.h>
#include <sys/ioctl.h>
#include <libgen.h>
#include <mntent.h>
#include <uuid/uuid.h>
@ -55,82 +56,35 @@ struct btrfs_send {
int find_mount_root(const char *path, char **mount_root)
{
int ret;
char *cur;
char fsid[BTRFS_FSID_SIZE];
FILE *mnttab;
int fd;
struct stat st;
char *tmp;
char *dup = NULL;
struct btrfs_ioctl_fs_info_args args;
struct mntent *ent;
int len;
int longest_matchlen = 0;
char *longest_match = NULL;
fd = open(path, O_RDONLY | O_NOATIME);
if (fd < 0) {
ret = -errno;
goto out;
}
ret = fstat(fd, &st);
if (fd < 0) {
ret = -errno;
goto out;
}
if (!S_ISDIR(st.st_mode)) {
ret = -ENOTDIR;
goto out;
}
ret = ioctl(fd, BTRFS_IOC_FS_INFO, &args);
if (fd < 0) {
ret = -errno;
goto out;
}
memcpy(fsid, args.fsid, BTRFS_FSID_SIZE);
if (fd < 0)
return -errno;
close(fd);
fd = -1;
cur = strdup(path);
while (1) {
dup = strdup(cur);
tmp = dirname(dup);
if (!tmp)
break;
fd = open(tmp, O_RDONLY | O_NOATIME);
if (fd < 0) {
ret = -errno;
goto out;
mnttab = fopen("/etc/mtab", "r");
while ((ent = getmntent(mnttab))) {
len = strlen(ent->mnt_dir);
if (strncmp(ent->mnt_dir, path, len) == 0) {
/* match found */
if (longest_matchlen < len) {
free(longest_match);
longest_matchlen = len;
longest_match = strdup(ent->mnt_dir);
}
}
}
ret = ioctl(fd, BTRFS_IOC_FS_INFO, &args);
close(fd);
fd = -1;
if (ret < 0)
break;
if (memcmp(fsid, args.fsid, BTRFS_FSID_SIZE) != 0)
break;
*mount_root = realpath(longest_match, NULL);
free(longest_match);
free(cur);
cur = strdup(tmp);
free(dup);
dup = NULL;
if (strcmp(cur, "/") == 0)
break;
if (strcmp(cur, ".") == 0)
break;
}
ret = 0;
*mount_root = realpath(cur, NULL);
out:
if (dup)
free(dup);
if (fd != -1)
close(fd);
return ret;
return 0;
}
static int get_root_id(struct btrfs_send *s, const char *path, u64 *root_id)