From b276e4bc50b6ca99056a45315ea859c68d58fc1b Mon Sep 17 00:00:00 2001 From: Jeff Mahoney Date: Wed, 4 Jun 2014 16:43:11 -0400 Subject: btrfs-progs: canonicalize pathnames for device commands mount(8) will canonicalize pathnames before passing them to the kernel. Links to e.g. /dev/sda will be resolved to /dev/sda. Links to /dev/dm-# will be resolved using the name of the device mapper table to /dev/mapper/. Btrfs will use whatever name the user passes to it, regardless of whether it is canonical or not. That means that if a 'btrfs device ready' is issued on any device node pointing to the original device, it will adopt the new name instead of the name that was used during mount. Mounting using /dev/sdb2 will result in df: /dev/sdb2 209715200 39328 207577088 1% /mnt lrwxrwxrwx 1 root root 4 Jun 4 13:36 /dev/whatever-i-like -> sdb2 /dev/whatever-i-like 209715200 39328 207577088 1% /mnt Likewise, mounting with /dev/mapper/whatever and using /dev/dm-0 with a btrfs device command results in df showing /dev/dm-0. This can happen with multipath devices with friendly names enabled and doing something like 'partprobe' which (at least with our version) ends up issuing a 'change' uevent on the sysfs node. That *always* uses the dm-# name, and we get confused users. This patch does the same canonicalization of the paths that mount does so that we don't end up having inconsistent names reported by ->show_devices later. Signed-off-by: Jeff Mahoney [use PATH_MAX in canonicalize_dm_name] Signed-off-by: David Sterba --- cmds-device.c | 60 +++++++++++++++++++++++++++++++++++++++++++++------------- cmds-replace.c | 13 +++++++++++-- utils.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ utils.h | 2 ++ 4 files changed, 118 insertions(+), 15 deletions(-) diff --git a/cmds-device.c b/cmds-device.c index 29da661e..d7af0901 100644 --- a/cmds-device.c +++ b/cmds-device.c @@ -94,6 +94,7 @@ static int cmd_add_dev(int argc, char **argv) int devfd, res; u64 dev_block_count = 0; int mixed = 0; + char *path; res = test_dev_for_mkfs(argv[i], force, estr); if (res) { @@ -117,15 +118,24 @@ static int cmd_add_dev(int argc, char **argv) goto error_out; } - strncpy_null(ioctl_args.name, argv[i]); + path = canonicalize_path(argv[i]); + if (!path) { + fprintf(stderr, + "ERROR: Could not canonicalize pathname '%s': %s\n", + argv[i], strerror(errno)); + ret++; + goto error_out; + } + + strncpy_null(ioctl_args.name, path); res = ioctl(fdmnt, BTRFS_IOC_ADD_DEV, &ioctl_args); e = errno; - if(res<0){ + if (res < 0) { fprintf(stderr, "ERROR: error adding the device '%s' - %s\n", - argv[i], strerror(e)); + path, strerror(e)); ret++; } - + free(path); } error_out: @@ -241,6 +251,7 @@ static int cmd_scan_dev(int argc, char **argv) for( i = devstart ; i < argc ; i++ ){ struct btrfs_ioctl_vol_args args; + char *path; if (!is_block_device(argv[i])) { fprintf(stderr, @@ -248,9 +259,17 @@ static int cmd_scan_dev(int argc, char **argv) ret = 1; goto close_out; } - printf("Scanning for Btrfs filesystems in '%s'\n", argv[i]); + path = canonicalize_path(argv[i]); + if (!path) { + fprintf(stderr, + "ERROR: Could not canonicalize path '%s': %s\n", + argv[i], strerror(errno)); + ret = 1; + goto close_out; + } + printf("Scanning for Btrfs filesystems in '%s'\n", path); - strncpy_null(args.name, argv[i]); + strncpy_null(args.name, path); /* * FIXME: which are the error code returned by this ioctl ? * it seems that is impossible to understand if there no is @@ -261,9 +280,11 @@ static int cmd_scan_dev(int argc, char **argv) if( ret < 0 ){ fprintf(stderr, "ERROR: unable to scan the device '%s' - %s\n", - argv[i], strerror(e)); + path, strerror(e)); + free(path); goto close_out; } + free(path); } close_out: @@ -283,6 +304,7 @@ static int cmd_ready_dev(int argc, char **argv) struct btrfs_ioctl_vol_args args; int fd; int ret; + char *path; if (check_argc_min(argc, 2)) usage(cmd_ready_dev_usage); @@ -292,22 +314,34 @@ static int cmd_ready_dev(int argc, char **argv) perror("failed to open /dev/btrfs-control"); return 1; } - if (!is_block_device(argv[1])) { + + path = canonicalize_path(argv[argc - 1]); + if (!path) { fprintf(stderr, - "ERROR: %s is not a block device\n", argv[1]); - close(fd); - return 1; + "ERROR: Could not canonicalize pathname '%s': %s\n", + argv[argc - 1], strerror(errno)); + ret = 1; + goto out; } - strncpy(args.name, argv[argc - 1], BTRFS_PATH_NAME_MAX); + if (!is_block_device(path)) { + fprintf(stderr, + "ERROR: %s is not a block device\n", path); + ret = 1; + goto out; + } + + strncpy(args.name, path, BTRFS_PATH_NAME_MAX); ret = ioctl(fd, BTRFS_IOC_DEVICES_READY, &args); if (ret < 0) { fprintf(stderr, "ERROR: unable to determine if the device '%s'" - " is ready for mounting - %s\n", argv[argc - 1], + " is ready for mounting - %s\n", path, strerror(errno)); ret = 1; } +out: + free(path); close(fd); return ret; } diff --git a/cmds-replace.c b/cmds-replace.c index 9eb981ba..186a127f 100644 --- a/cmds-replace.c +++ b/cmds-replace.c @@ -134,7 +134,7 @@ static int cmd_start_replace(int argc, char **argv) int fddstdev = -1; char *path; char *srcdev; - char *dstdev; + char *dstdev = NULL; int avoid_reading_from_srcdev = 0; int force_using_targetdev = 0; struct stat st; @@ -209,7 +209,12 @@ static int cmd_start_replace(int argc, char **argv) } srcdev = argv[optind]; - dstdev = argv[optind + 1]; + dstdev = canonicalize_path(argv[optind + 1]); + if (!dstdev) { + fprintf(stderr, + "ERROR: Could not canonicalize path '%s': %s\n", + argv[optind + 1], strerror(errno)); + } if (is_numerical(srcdev)) { struct btrfs_ioctl_fs_info_args fi_args; @@ -283,6 +288,8 @@ static int cmd_start_replace(int argc, char **argv) close(fddstdev); fddstdev = -1; + free(dstdev); + dstdev = NULL; dev_replace_handle_sigint(fdmnt); if (!do_not_background) { @@ -317,6 +324,8 @@ static int cmd_start_replace(int argc, char **argv) return 0; leave_with_error: + if (dstdev) + free(dstdev); if (fdmnt != -1) close(fdmnt); if (fdsrcdev != -1) diff --git a/utils.c b/utils.c index 46d47d53..c718d0f6 100644 --- a/utils.c +++ b/utils.c @@ -1026,6 +1026,64 @@ static int blk_file_in_dev_list(struct btrfs_fs_devices* fs_devices, return 0; } +/* + * Resolve a pathname to a device mapper node to /dev/mapper/ + * Returns NULL on invalid input or malloc failure; Other failures + * will be handled by the caller using the input pathame. + */ +char *canonicalize_dm_name(const char *ptname) +{ + FILE *f; + size_t sz; + char path[PATH_MAX], name[PATH_MAX], *res = NULL; + + if (!ptname || !*ptname) + return NULL; + + snprintf(path, sizeof(path), "/sys/block/%s/dm/name", ptname); + if (!(f = fopen(path, "r"))) + return NULL; + + /* read \n from sysfs */ + if (fgets(name, sizeof(name), f) && (sz = strlen(name)) > 1) { + name[sz - 1] = '\0'; + snprintf(path, sizeof(path), "/dev/mapper/%s", name); + + if (access(path, F_OK) == 0) + res = strdup(path); + } + fclose(f); + return res; +} + +/* + * Resolve a pathname to a canonical device node, e.g. /dev/sda1 or + * to a device mapper pathname. + * Returns NULL on invalid input or malloc failure; Other failures + * will be handled by the caller using the input pathame. + */ +char *canonicalize_path(const char *path) +{ + char *canonical, *p; + + if (!path || !*path) + return NULL; + + canonical = realpath(path, NULL); + if (!canonical) + return strdup(path); + p = strrchr(canonical, '/'); + if (p && strncmp(p, "/dm-", 4) == 0 && isdigit(*(p + 4))) { + char *dm = canonicalize_dm_name(p + 1); + + if (dm) { + free(canonical); + return dm; + } + } + return canonical; +} + /* * returns 1 if the device was mounted, < 0 on error or 0 if everything * is safe to continue. diff --git a/utils.h b/utils.h index 4cfd315a..37fe1ba0 100644 --- a/utils.h +++ b/utils.h @@ -53,6 +53,8 @@ int btrfs_add_to_fsid(struct btrfs_trans_handle *trans, int btrfs_scan_for_fsid(int run_ioctls); void btrfs_register_one_device(char *fname); int btrfs_scan_one_dir(char *dirname, int run_ioctl); +char *canonicalize_dm_name(const char *ptname); +char *canonicalize_path(const char *path); int check_mounted(const char *devicename); int check_mounted_where(int fd, const char *file, char *where, int size, struct btrfs_fs_devices **fs_devices_mnt); -- cgit v1.2.3