Btrfs-progs: fix detection of root objects in cmds-property.c

Several fixes:

1) The function check_is_root() returns 0 if the object is root;

2) Don't treat any error from get fsid ioctl as meaning the target
   is root. Only -ENOTTY means it's a root (parent directory is
   not a btrfs fs) and a -ENOTDIR means our target object is not a
   directory, therefore it can be the root;

3) Fix the comparison of the target and target's parent fs ids. If
   they are different, it means the target is a mount point in a
   btrfs fs, therefore it's a root, otherwise it isn't.

Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>

diff --git a/cmds-property.c b/cmds-property.c
index 6699e61..3d1f18c 100644 (file)
--- a/cmds-property.c
+++ b/cmds-property.c
@@ -75,7 +75,7 @@ static int parse_prop(const char *arg, const struct prop_handler *props,
        return -1;
 }
 
-static int get_fsid(const char *path, u8 *fsid)
+static int get_fsid(const char *path, u8 *fsid, int silent)
 {
        int ret;
        int fd;
@@ -84,7 +84,8 @@ static int get_fsid(const char *path, u8 *fsid)
        fd = open(path, O_RDONLY);
        if (fd < 0) {
                ret = -errno;
-               fprintf(stderr, "ERROR: open %s failed. %s\n", path,
+               if (!silent)
+                       fprintf(stderr, "ERROR: open %s failed. %s\n", path,
                                strerror(-ret));
                goto out;
        }
@@ -109,7 +110,7 @@ static int check_btrfs_object(const char *object)
        int ret;
        u8 fsid[BTRFS_FSID_SIZE];
 
-       ret = get_fsid(object, fsid);
+       ret = get_fsid(object, fsid, 0);
        if (ret < 0)
                ret = 0;
        else
@@ -134,20 +135,27 @@ static int check_is_root(const char *object)
                strcat(tmp, "/");
        strcat(tmp, "..");
 
-       ret = get_fsid(object, fsid);
+       ret = get_fsid(object, fsid, 0);
        if (ret < 0) {
                fprintf(stderr, "ERROR: get_fsid for %s failed. %s\n", object,
                                strerror(-ret));
                goto out;
        }
 
-       ret = get_fsid(tmp, fsid2);
-       if (ret < 0) {
+       ret = get_fsid(tmp, fsid2, 1);
+       if (ret == -ENOTTY) {
                ret = 0;
                goto out;
+       } else if (ret == -ENOTDIR) {
+               ret = 1;
+               goto out;
+       } else if (ret < 0) {
+               fprintf(stderr, "ERROR: get_fsid for %s failed. %s\n", tmp,
+                       strerror(-ret));
+               goto out;
        }
 
-       if (!memcmp(fsid, fsid2, BTRFS_FSID_SIZE)) {
+       if (memcmp(fsid, fsid2, BTRFS_FSID_SIZE)) {
                ret = 0;
                goto out;
        }
@@ -195,7 +203,7 @@ static int autodetect_object_types(const char *object, int *types_out)
                ret = check_is_root(object);
                if (ret < 0)
                        goto out;
-               if (ret)
+               if (!ret)
                        types |= prop_object_root;
        }