Old kernel like 2.6.32 does 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 <[email protected]> --- cmds-filesystem.c | 7 ++++++- utils.c | 18 +++++++++--------- utils.h | 1 + 3 files changed, 16 insertions(+), 10 deletions(-) diff --git a/cmds-filesystem.c b/cmds-filesystem.c index 8822695..793df0e 100644 --- a/cmds-filesystem.c +++ b/cmds-filesystem.c @@ -468,7 +468,12 @@ 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((char *) dev_info_arg->path, label); + + if (ret) { kfree(dev_info_arg); goto out; } diff --git a/utils.c b/utils.c index afc97ee..297c5a3 100644 --- a/utils.c +++ b/utils.c @@ -1741,7 +1741,7 @@ 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; @@ -1751,11 +1751,6 @@ 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. @@ -1780,6 +1775,7 @@ 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) { @@ -1788,10 +1784,14 @@ 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 get label %s\n", strerror(errno)); + } + ret = -errno; close(fd); - return -1; + return ret; } strncpy(labelp, label, sizeof(label)); diff --git a/utils.h b/utils.h index 24d7aa5..4f7bb6f 100644 --- a/utils.h +++ b/utils.h @@ -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); -- 2.4.1 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
