This patch make output of filesystem-resize command more readable and
give detail information for users. This patch provides more information
about filesystem like below.

Before:
Resize '/mnt' of '1:-1G'

After:
Resize device id 1 (/dev/vdb) from 4.00GiB to 3.00GiB

Signed-off-by: Sidong Yang <redacted>
---
v2:
  - print more detailed error
  - covers all the possibilities format provides
v3:
  - use snprintf than strcpy for safety
  - add diff variable for code readability
v4:
  - fix bugs for argument that has no devid
---
 cmds/filesystem.c | 120 +++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 119 insertions(+), 1 deletion(-)

diff --git a/cmds/filesystem.c b/cmds/filesystem.c
index 0d23daf4..7ddf5880 100644
--- a/cmds/filesystem.c
+++ b/cmds/filesystem.c

@@ -28,6 +28,7 @@
 #include <linux/limits.h>
 #include <linux/version.h>
 #include <getopt.h>
+#include <limits.h>
 
 #include <btrfsutil.h>
 

@@ -1074,6 +1075,117 @@ static const char * const cmd_filesystem_resize_usage[] = {
 	NULL
 };
 
+static int check_resize_args(const char *amount, const char *path) {
+	struct btrfs_ioctl_fs_info_args fi_args;
+	struct btrfs_ioctl_dev_info_args *di_args = NULL;
+	int ret, i, dev_idx = -1;
+	u64 devid = 1;
+	const char *res_str = NULL;
+	char *devstr = NULL, *sizestr = NULL;
+	u64 new_size = 0, old_size = 0, diff = 0;
+	int mod = 0;
+	char amount_dup[BTRFS_VOL_NAME_MAX];
+
+	ret = get_fs_info(path, &fi_args, &di_args);
+
+	if (ret) {
+		error("unable to retrieve fs info");
+		return 1;
+	}
+
+	if (!fi_args.num_devices) {
+		error("no devices found");
+		free(di_args);
+		return 1;