scoutfs-utils: add stat command

The scoutfs stat command is modeled after stat(1) and uses the STAT_MORE
ioctl.

Signed-off-by: Zach Brown <zab@versity.com>

utils/src/ioctl.h

@@ -10,6 +10,27 @@ struct scoutfs_ioctl_walk_inodes_entry {
 	__u64 ino;
 } __packed;
 
+/*
+ * Walk inodes in an index that is sorted by one of their fields.
+ *
+ * Each index is built from generic index items that have major and
+ * minor values that are set to the field being indexed.  In time
+ * indices, for example, major is seconds and minor is nanoseconds.
+ *
+ * @first       The first index entry that can be returned.
+ * @last        The last index entry that can be returned.
+ * @entries_ptr Pointer to emory containing buffer for entry results.
+ * @nr_entries  The number of entries that can fit in the buffer.
+ * @index       Which index to walk, enumerated in _WALK_INODES_ constants.
+ *
+ * To start iterating first can be memset to 0 and last to 0xff.  Then
+ * after each set of results first can be set to the last entry returned
+ * and then the fields can be incremented in reverse sort order (ino <
+ * minor < major) as each increasingly significant value wraps around to
+ * 0.
+ *
+ * If first is greater than last then the walk will return 0 entries.
+ */
 struct scoutfs_ioctl_walk_inodes {
 	struct scoutfs_ioctl_walk_inodes_entry first;
 	struct scoutfs_ioctl_walk_inodes_entry last;
@@ -107,4 +128,25 @@ struct scoutfs_ioctl_stage {
 #define SCOUTFS_IOC_STAGE _IOW(SCOUTFS_IOCTL_MAGIC, 6, \
 			       struct scoutfs_ioctl_stage)
 
+/*
+ * Give the user inode fields that are not otherwise visible.  statx()
+ * isn't always available and xattrs are relatively expensive.
+ *
+ * @valid_bytes stores the number of bytes that are valid in the
+ * structure.  The caller sets this to the size of the struct that they
+ * understand.  The kernel then fills and copies back the min of the
+ * size they and the user caller understand.  The user can tell if a
+ * field is set if all of its bytes are within the valid_bytes that the
+ * kernel set on return.
+ *
+ * New fields are only added to the end of the struct.
+ */
+struct scoutfs_ioctl_stat_more {
+	__u64 valid_bytes;
+	__u64 data_version;
+} __packed;
+
+#define SCOUTFS_IOC_STAT_MORE _IOW(SCOUTFS_IOCTL_MAGIC, 7, \
+				   struct scoutfs_ioctl_stat_more)
+
 #endif

utils/src/stage_release.c

@@ -193,41 +193,3 @@ static void __attribute__((constructor)) release_ctor(void)
 	cmd_register("release", "<path> <vers> <offset> <count>",
 		     "mark file region offline and free extents", release_cmd);
 }
-
-static int data_version_cmd(int argc, char **argv)
-{
-	u64 vers;
-	int ret;
-	int fd;
-
-	if (argc != 1) {
-		fprintf(stderr, "must specify path\n");
-		return -EINVAL;
-	}
-
-	fd = open(argv[0], O_RDWR);
-	if (fd < 0) {
-		ret = -errno;
-		fprintf(stderr, "failed to open '%s': %s (%d)\n",
-			argv[0], strerror(errno), errno);
-		return ret;
-	}
-
-	ret = ioctl(fd, SCOUTFS_IOC_DATA_VERSION, &vers);
-	if (ret < 0) {
-		ret = -errno;
-		fprintf(stderr, "data version ioctl failed: %s (%d)\n",
-			strerror(errno), errno);
-	} else {
-		printf("%llu\n", vers);
-	}
-
-	close(fd);
-	return ret;
-};
-
-static void __attribute__((constructor)) data_version_ctor(void)
-{
-	cmd_register("data_version", "<path>",
-		     "print the file's data version", data_version_cmd);
-}

utils/src/stat.c

@@ -0,0 +1,65 @@
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/ioctl.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <string.h>
+
+#include "sparse.h"
+#include "util.h"
+#include "format.h"
+#include "ioctl.h"
+#include "cmd.h"
+
+static int stat_more_cmd(int argc, char **argv)
+{
+	struct scoutfs_ioctl_stat_more stm;
+	char *path;
+	int ret;
+	int fd;
+	int i;
+
+	if (argc == 0) {
+		fprintf(stderr, "must specify at least one path argument\n");
+		return -EINVAL;
+	}
+
+	for (i = 0; i < argc; i++) {
+		path = argv[i];
+
+		fd = open(path, O_RDONLY);
+		if (fd < 0) {
+			ret = -errno;
+			fprintf(stderr, "failed to open '%s': %s (%d)\n",
+				path, strerror(errno), errno);
+			continue;
+		}
+
+		memset(&stm, 0, sizeof(stm));
+		stm.valid_bytes = sizeof(stm);
+
+		ret = ioctl(fd, SCOUTFS_IOC_STAT_MORE, &stm);
+		if (ret < 0) {
+			ret = -errno;
+			fprintf(stderr, "stat_more ioctl failed on '%s': "
+				"%s (%d)\n", path, strerror(errno), errno);
+		} else {
+			printf("          File: '%s'\n"
+			       "  data_version: %-20llu\n",
+				path, stm.data_version);
+		}
+
+		close(fd);
+	}
+
+	return 0;
+}
+
+static void __attribute__((constructor)) stat_more_ctor(void)
+{
+	cmd_register("stat", "<path>",
+		     "print scoutfs stat information for path", stat_more_cmd);
+}