Jeff Liu
2012-Dec-17 11:34 UTC
[PATCH v5 1/4] Btrfs-progs: get label of a mounted file system
With this new ioctl(2), we can get the label for a mounted file system.
It still does normal process to fetch label if the specified file system is
unmounted.
Signed-off-by: Jie Liu <jeff.liu@oracle.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
btrfslabel.c | 74 ++++++++++++++++++++++++++++++++++++++--------------------
ioctl.h | 2 ++
utils.c | 2 +-
utils.h | 1 +
4 files changed, 53 insertions(+), 26 deletions(-)
diff --git a/btrfslabel.c b/btrfslabel.c
index cb142b0..443eff6 100644
--- a/btrfslabel.c
+++ b/btrfslabel.c
@@ -67,45 +67,69 @@ static void change_label_unmounted(char *dev, char *nLabel)
close_ctree(root);
}
-int get_label_unmounted(char *dev)
+static int get_label_unmounted(const char *dev)
{
- struct btrfs_root *root;
+ struct btrfs_root *root;
+ int ret;
- /* Open the super_block at the default location
- * and as read-only.
- */
- root = open_ctree(dev, 0, 0);
+ ret = check_mounted(dev);
+ if (ret < 0) {
+ 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;
+ }
- if(!root)
- return -1;
+ /* Open the super_block at the default location
+ * and as read-only.
+ */
+ root = open_ctree(dev, 0, 0);
+ if(!root)
+ return -1;
- fprintf(stdout, "%s\n",
root->fs_info->super_copy.label);
+ fprintf(stdout, "%s\n", root->fs_info->super_copy.label);
- /* Now we close it since we are done. */
- close_ctree(root);
- return 0;
+ /* Now we close it since we are done. */
+ close_ctree(root);
+ return 0;
}
-int get_label(char *btrfs_dev)
+/*
+ * If a partition is mounted, try to get the filesystem label via its
+ * mounted path rather than device. Return the corresponding error
+ * the user specified the device path.
+ */
+static int get_label_mounted(const char *mount_path)
{
+ char label[BTRFS_LABEL_SIZE];
+ int fd;
- int ret;
- ret = check_mounted(btrfs_dev);
- if (ret < 0)
- {
- fprintf(stderr, "FATAL: error checking %s mount status\n",
btrfs_dev);
- return -1;
+ fd = open(mount_path, O_RDONLY | O_NOATIME);
+ if (fd < 0) {
+ fprintf(stderr, "ERROR: unable access to ''%s''\n",
mount_path);
+ return -1;
}
- if(ret != 0)
- {
- fprintf(stderr, "FATAL: the filesystem has to be
unmounted\n");
- return -2;
+ memset(label, ''\0'', sizeof(label));
+ if (ioctl(fd, BTRFS_IOC_GET_FSLABEL, label) < 0) {
+ fprintf(stderr, "ERROR: unable get label %s\n", strerror(errno));
+ close(fd);
+ return -1;
}
- ret = get_label_unmounted(btrfs_dev);
- return ret;
+
+ fprintf(stdout, "%s\n", label);
+ return 0;
}
+int get_label(const char *btrfs_dev)
+{
+ return is_existing_blk_or_reg_file(btrfs_dev) ?
+ get_label_unmounted(btrfs_dev) :
+ get_label_mounted(btrfs_dev);
+}
int set_label(char *btrfs_dev, char *nLabel)
{
diff --git a/ioctl.h b/ioctl.h
index 6fda3a1..0807b05 100644
--- a/ioctl.h
+++ b/ioctl.h
@@ -432,4 +432,6 @@ struct btrfs_ioctl_clone_range_args {
struct btrfs_ioctl_qgroup_create_args)
#define BTRFS_IOC_QGROUP_LIMIT _IOR(BTRFS_IOCTL_MAGIC, 43, \
struct btrfs_ioctl_qgroup_limit_args)
+#define BTRFS_IOC_GET_FSLABEL _IOR(BTRFS_IOCTL_MAGIC, 49, \
+ char[BTRFS_LABEL_SIZE])
#endif
diff --git a/utils.c b/utils.c
index 205e667..d59bca3 100644
--- a/utils.c
+++ b/utils.c
@@ -811,7 +811,7 @@ int check_mounted(const char* file)
return -errno;
}
- ret = check_mounted_where(fd, file, NULL, 0, NULL);
+ ret = check_mounted_where(fd, file, NULL, 0, NULL);
close(fd);
return ret;
diff --git a/utils.h b/utils.h
index 3a0368b..8750f28 100644
--- a/utils.h
+++ b/utils.h
@@ -46,4 +46,5 @@ int check_label(char *input);
int get_mountpt(char *dev, char *mntpt, size_t size);
int btrfs_scan_block_devices(int run_ioctl);
+int is_existing_blk_or_reg_file(const char* filename);
#endif
--
1.7.9.5
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