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btrfs-progs: provide fail safe for BTRFS_IOC_GET_FSLABEL ioctl 

Old kernels before 3.9 do not provide ioctl BTRFS_IOC_GET_FSLABEL.
So we need to provide a fail safe logic for btrfs-progs running
on those kernel.

In this patch when get_label_mounted() fails on the old kernel
it will fail back to the old method and uses get_label_unmounted(),
where it will read from the disk directly.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Anand Jain 2015-09-15 16:46:22 +08:00 committed by David Sterba
parent 3276a9f519
commit 94789777b9
3 changed files with 17 additions and 10 deletions
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8
cmds-filesystem.c
View File

@ -468,7 +468,13 @@ static int btrfs_scan_kernel(void *search, unsigned unit_mode)
goto out;
}
if (get_label_mounted(mnt->mnt_dir, label)) {
ret = get_label_mounted(mnt->mnt_dir, label);
/* provide backward kernel compatibility */
if (ret == -ENOTTY)
ret = get_label_unmounted(
(const char *)dev_info_arg->path, label);
if (ret) {
kfree(dev_info_arg);
goto out;
}

18
utils.c
View File

@ -1740,7 +1740,7 @@ static int set_label_mounted(const char *mount_path, const char *label)
return 0;
}
static int get_label_unmounted(const char *dev, char *label)
int get_label_unmounted(const char *dev, char *label)
{
struct btrfs_root *root;
int ret;
@ -1750,11 +1750,6 @@ static int get_label_unmounted(const char *dev, char *label)
fprintf(stderr, "FATAL: error checking %s mount status\n", dev);
return -1;
}
if (ret > 0) {
fprintf(stderr, "ERROR: dev %s is mounted, use mount point\n",
dev);
return -1;
}
/* Open the super_block at the default location
* and as read-only.
@ -1779,6 +1774,7 @@ int get_label_mounted(const char *mount_path, char *labelp)
{
char label[BTRFS_LABEL_SIZE];
int fd;
int ret;
fd = open(mount_path, O_RDONLY | O_NOATIME);
if (fd < 0) {
@ -1787,10 +1783,14 @@ int get_label_mounted(const char *mount_path, char *labelp)
}
memset(label, '\0', sizeof(label));
if (ioctl(fd, BTRFS_IOC_GET_FSLABEL, label) < 0) {
fprintf(stderr, "ERROR: unable get label %s\n", strerror(errno));
ret = ioctl(fd, BTRFS_IOC_GET_FSLABEL, label);
if (ret < 0) {
if (errno != ENOTTY)
fprintf(stderr, "ERROR: unable to get label %s\n",
strerror(errno));
ret = -errno;
close(fd);
return -1;
return ret;
}
strncpy(labelp, label, sizeof(label));

1
utils.h
View File

@ -164,6 +164,7 @@ u64 btrfs_device_size(int fd, struct stat *st);
#define strncpy_null(dest, src) __strncpy__null(dest, src, sizeof(dest))
int test_dev_for_mkfs(char *file, int force_overwrite);
int get_label_mounted(const char *mount_path, char *labelp);
int get_label_unmounted(const char *dev, char *label);
int test_num_disk_vs_raid(u64 metadata_profile, u64 data_profile,
u64 dev_cnt, int mixed);
int group_profile_max_safe_loss(u64 flags);