diff options
| -rw-r--r-- | kerncompat.h | 4 | ||||
| -rw-r--r-- | utils.c | 237 | ||||
| -rw-r--r-- | utils.h | 2 |
3 files changed, 210 insertions, 33 deletions
diff --git a/kerncompat.h b/kerncompat.h index e4c8ce0c..46236cd5 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)) @@ -31,6 +31,10 @@ #include <fcntl.h> #include <unistd.h> #include <mntent.h> +#include <linux/loop.h> +#include <linux/major.h> +#include <linux/kdev_t.h> +#include <limits.h> #include "kerncompat.h" #include "radix-tree.h" #include "ctree.h" @@ -586,55 +590,224 @@ error: return ret; } +/* checks if a device is a loop device */ +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); +} + + +/* Takes a loop device path (e.g. /dev/loop0) and returns + * the associated file (e.g. /images/my_btrfs.img) */ +int resolve_loop_device(const char* loop_dev, char* loop_file, int max_len) +{ + int loop_fd; + int ret_ioctl; + struct loop_info loopinfo; + + if ((loop_fd = open(loop_dev, O_RDONLY)) < 0) + return -errno; + + ret_ioctl = ioctl(loop_fd, LOOP_GET_STATUS, &loopinfo); + close(loop_fd); + + if (ret_ioctl == 0) + strncpy(loop_file, loopinfo.lo_name, max_len); + else + return -errno; + + return 0; +} + +/* Checks whether a and b are identical or device + * files associated with the same block device + */ +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; +} + +/* checks if a and b are identical or device + * files associated with the same block device or + * if one file is a loop device that uses the other + * file. + */ +int is_same_loop_file(const char* a, const char* b) +{ + char res_a[PATH_MAX]; + char res_b[PATH_MAX]; + const char* final_a; + const char* final_b; + int ret; + + /* Resolve a if it is a loop device */ + if((ret = is_loop_device(a)) < 0) { + return ret; + } else if(ret) { + if((ret = resolve_loop_device(a, res_a, sizeof(res_a))) < 0) + return ret; + + final_a = res_a; + } else { + final_a = a; + } + + /* Resolve b if it is a loop device */ + if((ret = is_loop_device(b)) < 0) { + return ret; + } else if(ret) { + if((ret = resolve_loop_device(b, res_b, sizeof(res_b))) < 0) + return ret; + + final_b = res_b; + } else { + final_b = b; + } + + return is_same_blk_file(final_a, final_b); +} + +/* Checks if a file exists and is a block or regular file*/ +int is_existing_blk_or_reg_file(const char* filename) +{ + struct stat st_buf; + + if(stat(filename, &st_buf) < 0) { + if(errno == ENOENT) + return 0; + else + return -errno; + } + + return (S_ISBLK(st_buf.st_mode) || S_ISREG(st_buf.st_mode)); +} + +/* Checks if a file is used (directly or indirectly via a loop device) + * by a device in fs_devices + */ +int blk_file_in_dev_list(struct btrfs_fs_devices* fs_devices, const char* file) +{ + int ret; + struct list_head *head; + struct list_head *cur; + struct btrfs_device *device; + + head = &fs_devices->devices; + list_for_each(cur, head) { + device = list_entry(cur, struct btrfs_device, dev_list); + + if((ret = is_same_loop_file(device->name, file))) + return ret; + } + + 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) +int check_mounted(const char* file) { - struct mntent *mnt; - struct stat st_buf; - dev_t file_dev = 0; - dev_t file_rdev = 0; - ino_t file_ino = 0; + int ret; + int fd; + u64 total_devs = 1; + int is_btrfs; + struct btrfs_fs_devices* fs_devices_mnt = NULL; FILE *f; - int ret = 0; + struct mntent *mnt; - if ((f = setmntent ("/proc/mounts", "r")) == NULL) + fd = open(file, O_RDONLY); + if (fd < 0) { + fprintf (stderr, "check_mounted(): Could not open %s\n", file); return -errno; + } - if (stat(file, &st_buf) < 0) { - 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; - } + /* scan the initial device */ + ret = btrfs_scan_one_device(fd, file, &fs_devices_mnt, + &total_devs, BTRFS_SUPER_INFO_OFFSET); + is_btrfs = (ret >= 0); + close(fd); + + /* scan other devices */ + if (is_btrfs && total_devs > 1) { + if((ret = btrfs_scan_for_fsid(fs_devices_mnt, total_devs, 1))) + return ret; } + /* iterate over the list of currently mountes filesystems */ + if ((f = setmntent ("/proc/mounts", "r")) == NULL) + return -errno; + while ((mnt = getmntent (f)) != NULL) { - if (strcmp(file, mnt->mnt_fsname) == 0) - break; + if(is_btrfs) { + 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))) { - break; - } + ret = blk_file_in_dev_list(fs_devices_mnt, mnt->mnt_fsname); + } else { + /* ignore entries in the mount table that are not + associated with a file*/ + if((ret = is_existing_blk_or_reg_file(mnt->mnt_fsname)) < 0) + goto out_mntloop_err; + else if(!ret) + continue; + + ret = is_same_loop_file(file, mnt->mnt_fsname); } - } - if (mnt) { - /* found an entry in mnt table */ - ret = 1; + if(ret < 0) + goto out_mntloop_err; + else if(ret) + break; } + /* Did we find an entry in mnt table? */ + ret = (mnt != NULL); + +out_mntloop_err: endmntent (f); + return ret; } @@ -36,7 +36,7 @@ int btrfs_scan_for_fsid(struct btrfs_fs_devices *fs_devices, u64 total_devs, int run_ioctls); void btrfs_register_one_device(char *fname); int btrfs_scan_one_dir(char *dirname, int run_ioctl); -int check_mounted(char *devicename); +int check_mounted(const char *devicename); int btrfs_device_already_in_root(struct btrfs_root *root, int fd, int super_offset); char *pretty_sizes(u64 size); |