metadisp: new translator for data and metadata separation

Summary:

feature/metadisp is an xlator for performing "metadata dispersal" across
multiple children. it does this by flattening the complex
POSIX paths into /$GFID style paths, then forwarding the
metadata operations to its first child and forwarding the
data operations to its second child.

The purpose of this xlator is to allow separation of data and metadata,
in cases where metadata might be stored in another format (embedded kv?),
on another disk (ssd), on another host (dht2).

Change-Id: I392c8bd0c867a3237d144aea327323f700a2728d
Updates: #816
Signed-Off-By: Sheena Artrip <sheenobu@fb.com>
Tested-By: Amar Tumballi <amar@kadalu.io>

1 files changed, 107 insertions, 0 deletions

diff --git a/tests/basic/metadisp/fxattr.c b/tests/basic/metadisp/fxattr.c
new file mode 100644
index 00000000000..e552057778a
--- /dev/null
+++ b/tests/basic/metadisp/fxattr.c
@@ -0,0 +1,107 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <fcntl.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/xattr.h>
+
+static char MY_XATTR[] = "user.fxtest";
+static char *PROGRAM;
+#define CONSUME(v)                                                             \
+    do {                                                                       \
+        if (!argc) {                                                           \
+            fprintf(stderr, "missing argument\n");                             \
+            return EXIT_FAILURE;                                               \
+        }                                                                      \
+        v = argv[0];                                                           \
+        ++argv;                                                                \
+        --argc;                                                                \
+    } while (0)
+
+static int
+do_get(int argc, char **argv, int fd)
+{
+    char *value;
+    int ret;
+    char buf[1024];
+
+    CONSUME(value);
+
+    ret = fgetxattr(fd, MY_XATTR, buf, sizeof(buf));
+    if (ret == (-1)) {
+        perror("fgetxattr");
+        return EXIT_FAILURE;
+    }
+
+    if (strncmp(buf, value, ret) != 0) {
+        fprintf(stderr, "data mismatch\n");
+        return EXIT_FAILURE;
+    }
+
+    return EXIT_SUCCESS;
+}
+
+static int
+do_set(int argc, char **argv, int fd)
+{
+    char *value;
+    int ret;
+
+    CONSUME(value);
+
+    ret = fsetxattr(fd, MY_XATTR, value, strlen(value), 0);
+    if (ret == (-1)) {
+        perror("fsetxattr");
+        return EXIT_FAILURE;
+    }
+
+    return EXIT_SUCCESS;
+}
+
+static int
+do_remove(int argc, char **argv, int fd)
+{
+    int ret;
+
+    ret = fremovexattr(fd, MY_XATTR);
+    if (ret == (-1)) {
+        perror("femovexattr");
+        return EXIT_FAILURE;
+    }
+
+    return EXIT_SUCCESS;
+}
+
+int
+main(int argc, char **argv)
+{
+    int fd;
+    char *path;
+    char *cmd;
+
+    CONSUME(PROGRAM);
+    CONSUME(path);
+    CONSUME(cmd);
+
+    fd = open(path, O_RDWR);
+    if (fd == (-1)) {
+        perror("open");
+        return EXIT_FAILURE;
+    }
+
+    if (strcmp(cmd, "get") == 0) {
+        return do_get(argc, argv, fd);
+    }
+
+    if (strcmp(cmd, "set") == 0) {
+        return do_set(argc, argv, fd);
+    }
+
+    if (strcmp(cmd, "remove") == 0) {
+        return do_remove(argc, argv, fd);
+    }
+
+    return EXIT_SUCCESS;
+}