btrfs-progs: check for negative return value from ioctl

Handle only negative values returned by ioctl syscalls, with exception
of the device remove. It returns positive values that are handled later.

Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/cmds-device.c b/cmds-device.c
index f69d0248..50c1c5df 100644
--- a/cmds-device.c
+++ b/cmds-device.c
@@ -166,6 +166,10 @@ static int _cmd_device_remove(int argc, char **argv,
 		}
 		memset(&arg, 0, sizeof(arg));
 		strncpy_null(arg.name, argv[i]);
+		/*
+		 * Positive values are from BTRFS_ERROR_DEV_*,
+		 * otherwise it's a generic error, one of errnos
+		 */
 		res = ioctl(fdmnt, BTRFS_IOC_RM_DEV, &arg);
 		if (res) {
 			const char *msg;