btrfs-progs: balance: use btrfs_open_dir for btrfs balance command

We can use btrfs_open_dir() to check whether target dir is
in btrfs's mount point before open, instead of checking it in
kernel space of ioctl, and return fuzzy error message.

Before patch:
  # btrfs balance start /mnt/tmp
  ERROR: error during balancing '/mnt/tmp' - Inappropriate ioctl for device
  There may be more info in syslog - try dmesg | tail
  #

After patch:
  # btrfs balance start /mnt/tmp
  ERROR: not btrfs filesystem: /mnt/tmp
  #

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/cmds-balance.c b/cmds-balance.c
index 9af218b..b02e40d 100644 (file)
--- a/cmds-balance.c
+++ b/cmds-balance.c
@@ -306,11 +306,9 @@ static int do_balance(const char *path, struct btrfs_ioctl_balance_args *args,
        int e;
        DIR *dirstream = NULL;
 
-       fd = open_file_or_dir(path, &dirstream);
-       if (fd < 0) {
-               fprintf(stderr, "ERROR: can't access '%s'\n", path);
+       fd = btrfs_open_dir(path, &dirstream, 1);
+       if (fd < 0)
                return 1;
-       }
 
        ret = ioctl(fd, BTRFS_IOC_BALANCE_V2, args);
        e = errno;
@@ -503,11 +501,9 @@ static int cmd_balance_pause(int argc, char **argv)
 
        path = argv[1];
 
-       fd = open_file_or_dir(path, &dirstream);
-       if (fd < 0) {
-               fprintf(stderr, "ERROR: can't access '%s'\n", path);
+       fd = btrfs_open_dir(path, &dirstream, 1);
+       if (fd < 0)
                return 1;
-       }
 
        ret = ioctl(fd, BTRFS_IOC_BALANCE_CTL, BTRFS_BALANCE_CTL_PAUSE);
        e = errno;
@@ -544,11 +540,9 @@ static int cmd_balance_cancel(int argc, char **argv)
 
        path = argv[1];
 
-       fd = open_file_or_dir(path, &dirstream);
-       if (fd < 0) {
-               fprintf(stderr, "ERROR: can't access '%s'\n", path);
+       fd = btrfs_open_dir(path, &dirstream, 1);
+       if (fd < 0)
                return 1;
-       }
 
        ret = ioctl(fd, BTRFS_IOC_BALANCE_CTL, BTRFS_BALANCE_CTL_CANCEL);
        e = errno;
@@ -586,11 +580,9 @@ static int cmd_balance_resume(int argc, char **argv)
 
        path = argv[1];
 
-       fd = open_file_or_dir(path, &dirstream);
-       if (fd < 0) {
-               fprintf(stderr, "ERROR: can't access '%s'\n", path);
+       fd = btrfs_open_dir(path, &dirstream, 1);
+       if (fd < 0)
                return 1;
-       }
 
        memset(&args, 0, sizeof(args));
        args.flags |= BTRFS_BALANCE_RESUME;
@@ -679,11 +671,9 @@ static int cmd_balance_status(int argc, char **argv)
 
        path = argv[optind];
 
-       fd = open_file_or_dir(path, &dirstream);
-       if (fd < 0) {
-               fprintf(stderr, "ERROR: can't access '%s'\n", path);
+       fd = btrfs_open_dir(path, &dirstream, 1);
+       if (fd < 0)
                return 2;
-       }
 
        ret = ioctl(fd, BTRFS_IOC_BALANCE_PROGRESS, &args);
        e = errno;