[PATCH] btrfs-progs: subvolume: output the prompt line only when the ioctl succeeded

[Qu Wenruo <wqu@suse.com>]

[BUG]
With the latest kernel patch to reject invalid qgroupids in
btrfs_qgroup_inherit structure, "btrfs subvolume create" or "btrfs
subvolume snapshot" can lead to the following output:

 # mkfs.btrfs -O quota -f $dev
 # mount $dev $mnt
 # btrfs subvolume create -i 2/0 $mnt/subv1
 Create subvolume '/mnt/btrfs/subv1'
 ERROR: cannot create subvolume: No such file or directory

The "btrfs subvolume" command output the first line, seemingly to
indicate a successful subvolume creation, then followed by an error
message.

This can be a little confusing on whether if the subvolume is created or
not.

[FIX]
Fix the output by only outputting the regular line if the ioctl
succeeded.

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 cmds/subvolume.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/cmds/subvolume.c b/cmds/subvolume.c
index 00c5eacfa694..1549adaca642 100644
--- a/cmds/subvolume.c
+++ b/cmds/subvolume.c
@@ -229,7 +229,6 @@ static int create_one_subvolume(const char *dst, struct btrfs_qgroup_inherit *in
 		goto out;
 	}
 
-	pr_verbose(LOG_DEFAULT, "Create subvolume '%s/%s'\n", dstdir, newname);
 	if (inherit) {
 		struct btrfs_ioctl_vol_args_v2	args;
 
@@ -253,6 +252,7 @@ static int create_one_subvolume(const char *dst, struct btrfs_qgroup_inherit *in
 		error("cannot create subvolume: %m");
 		goto out;
 	}
+	pr_verbose(LOG_DEFAULT, "Create subvolume '%s/%s'\n", dstdir, newname);
 
 out:
 	close(fddst);
@@ -754,16 +754,8 @@ static int cmd_subvolume_snapshot(const struct cmd_struct *cmd, int argc, char *
 	if (fd < 0)
 		goto out;
 
-	if (readonly) {
+	if (readonly)
 		args.flags |= BTRFS_SUBVOL_RDONLY;
-		pr_verbose(LOG_DEFAULT,
-			   "Create a readonly snapshot of '%s' in '%s/%s'\n",
-			   subvol, dstdir, newname);
-	} else {
-		pr_verbose(LOG_DEFAULT,
-			   "Create a snapshot of '%s' in '%s/%s'\n",
-			   subvol, dstdir, newname);
-	}
 
 	args.fd = fd;
 	if (inherit) {
@@ -784,6 +776,15 @@ static int cmd_subvolume_snapshot(const struct cmd_struct *cmd, int argc, char *
 
 	retval = 0;	/* success */
 
+	if (readonly)
+		pr_verbose(LOG_DEFAULT,
+			   "Create a readonly snapshot of '%s' in '%s/%s'\n",
+			   subvol, dstdir, newname);
+	else
+		pr_verbose(LOG_DEFAULT,
+			   "Create a snapshot of '%s' in '%s/%s'\n",
+			   subvol, dstdir, newname);
+
 out:
 	close(fddst);
 	close(fd);
-- 
2.43.2