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/<name>.
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
# ls -la /dev/whatever-i-like lrwxrwxrwx 1 root root 4 Jun 4
13:36 /dev/whatever-i-like -> sdb2 # btrfs dev ready
/dev/whatever-i-like # df /mnt /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 <je...@suse.com> --- cmds-device.c |
60 ++++++++++++++++++++++++++++++++++++++++++++-------------
cmds-replace.c | 13 ++++++++++-- utils.c | 57
++++++++++++++++++++++++++++++++++++++++++++++++++++++ utils.h
| 2 + 4 files changed, 117 insertions(+), 15 deletions(-)
--- a/cmds-device.c +++ b/cmds-device.c @@ -95,6 +95,7 @@ static
int cmd_add_dev(int argc, char ** int devfd, res; u64
dev_block_count = 0; int mixed = 0; + char *path;
res = test_dev_for_mkfs(argv[i], force, estr); if (res) { @@
-118,15 +119,24 @@ static int cmd_add_dev(int argc, char ** 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: @@ -242,6 +252,7 @@ static int cmd_scan_dev(int argc,
char *
for( i = devstart ; i < argc ; i++ ){ struct btrfs_ioctl_vol_args
args; + char *path;
if (!is_block_device(argv[i])) { fprintf(stderr, @@ -249,9
+260,17 @@ static int cmd_scan_dev(int argc, char * 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 @@ -262,9 +281,11 @@ static int
cmd_scan_dev(int argc, char *
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: @@ -284,6 +305,7 @@ static int cmd_ready_dev(int argc,
char struct btrfs_ioctl_vol_args args; int fd; int ret;
+ char *path;
if (check_argc_min(argc, 2)) usage(cmd_ready_dev_usage); @@
-293,22 +315,34 @@ static int cmd_ready_dev(int argc, char
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; } ---
a/cmds-replace.c +++ b/cmds-replace.c @@ -134,7 +134,7 @@ static
int cmd_start_replace(int argc, c 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; @@ -204,7 +204,12 @@ static int
cmd_start_replace(int argc, c }
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; @@ -278,6 +283,8 @@ static int cmd_start_replace(int
argc, c
close(fddstdev); fddstdev = -1; + free(dstdev); + dstdev =
NULL;
dev_replace_handle_sigint(fdmnt); if (!do_not_background) { @@
-312,6 +319,8 @@ static int cmd_start_replace(int argc, c return
0;
leave_with_error: + if (dstdev) + free(dstdev); if
(fdmnt != -1) close(fdmnt); if (fdsrcdev != -1) --- a/utils.c +++
b/utils.c @@ -987,6 +987,63 @@ static int
blk_file_in_dev_list(struct b }
/* + * Resolve a pathname to a device mapper node to
/dev/mapper/<name> + * 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[256], name[256], *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 <name>\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. */ ---
a/utils.h +++ b/utils.h @@ -61,6 +61,8 @@ int
btrfs_add_to_fsid(struct btrfs_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);
