cephfs: imlplement readdir_snapdiff API

Signed-off-by: Denis Barahtanov <denis.barahtanov@croit.io>
Signed-off-by: Igor Fedotov <igor.fedotov@croit.io>

1 files changed, 120 insertions, 0 deletions

diff --git a/src/libcephfs.cc b/src/libcephfs.cc
index 99da0c5c5c8..51e73efdb65 100644
--- a/src/libcephfs.cc
+++ b/src/libcephfs.cc
@@ -19,6 +19,7 @@
 
 #include "auth/Crypto.h"
 #include "client/Client.h"
+#include "client/Inode.h"
 #include "librados/RadosClient.h"
 #include "common/async/context_pool.h"
 #include "common/ceph_argparse.h"
@@ -28,6 +29,7 @@
 #include "mon/MonClient.h"
 #include "include/str_list.h"
 #include "include/stringify.h"
+#include "include/object.h"
 #include "messages/MMonMap.h"
 #include "msg/Messenger.h"
 #include "include/ceph_assert.h"
@@ -687,6 +689,124 @@ extern "C" int ceph_readdirplus_r(struct ceph_mount_info *cmount, struct ceph_di
   return cmount->get_client()->readdirplus_r(reinterpret_cast<dir_result_t*>(dirp), de, stx, want, flags, out);
 }
 
+extern "C" int ceph_open_snapdiff(struct ceph_mount_info* cmount,
+                                  const char* root_path,
+                                  const char* rel_path,
+                                  const char* snap1,
+                                  const char* snap2,
+                                  struct ceph_snapdiff_info* out)
+{
+  if (!cmount->is_mounted()) {
+    /* we set errno to signal errors. */
+    errno = ENOTCONN;
+    return -errno;
+  }
+  if (!out || !root_path || !rel_path ||
+      !snap1 || !*snap1 || !snap2 || !*snap2) {
+    errno = EINVAL;
+    return -errno;
+  }
+  out->cmount = cmount;
+  out->dir1 = out->dir_aux = nullptr;
+
+  char full_path1[PATH_MAX];
+  char snapdir[PATH_MAX];
+  cmount->conf_get("client_snapdir", snapdir, sizeof(snapdir) - 1);
+  int n = snprintf(full_path1, PATH_MAX,
+    "%s/%s/%s/%s", root_path, snapdir, snap1, rel_path);
+  if (n < 0 || n == PATH_MAX) {
+    errno = ENAMETOOLONG;
+    return -errno;
+  }
+  char full_path2[PATH_MAX];
+  n = snprintf(full_path2, PATH_MAX,
+    "%s/%s/%s/%s", root_path, snapdir, snap2, rel_path);
+  if (n < 0 || n == PATH_MAX) {
+    errno = ENAMETOOLONG;
+    return -errno;
+  }
+
+  int r = ceph_opendir(cmount, full_path1, &(out->dir1));
+  if (r != 0) {
+    //it's OK to have one of the snap paths absent - attempting another one
+    r = ceph_opendir(cmount, full_path2, &(out->dir1));
+    if (r != 0) {
+      // both snaps are absent, giving up
+      errno = ENOENT;
+      return -errno;
+    }
+    std::swap(snap1, snap2); // will use snap1 to learn snap_other below
+  } else {
+    // trying to open second snapshot to learn snapid and
+    // get the entry loaded into the client cache if any.
+    r = ceph_opendir(cmount, full_path2, &(out->dir_aux));
+    //paranoic, rely on this value below
+    out->dir_aux = r == 0 ? out->dir_aux : nullptr;
+  }
+  if (!out->dir_aux) {
+    // now trying to learn the second snapshot's id by using snapshot's root
+    n = snprintf(full_path2, PATH_MAX,
+        "%s/%s/%s", root_path, snapdir, snap2);
+    ceph_assert(n > 0 && n < PATH_MAX); //we've already checked above
+                                        //that longer string fits.
+                                        // Hence unlikely to assert
+    r = ceph_opendir(cmount, full_path2, &(out->dir_aux));
+    if (r != 0) {
+      goto close_err;
+    }
+  }
+  return 0;
+
+close_err:
+  ceph_close_snapdiff(out);
+  return r;
+}
+
+extern "C" int ceph_readdir_snapdiff(struct ceph_snapdiff_info* snapdiff,
+                                     struct ceph_snapdiff_entry_t* out)
+{
+  if (!snapdiff->cmount->is_mounted()) {
+    /* also sets errno to signal errors. */
+    errno = ENOTCONN;
+    return -errno;
+  }
+  dir_result_t* d1 = reinterpret_cast<dir_result_t*>(snapdiff->dir1);
+  dir_result_t* d2 = reinterpret_cast<dir_result_t*>(snapdiff->dir_aux);
+  if (!d1 || !d2 || !d1->inode || !d2->inode) {
+    errno = EINVAL;
+    return -errno;
+  }
+  snapid_t snapid;
+  int r = snapdiff->cmount->get_client()->readdir_snapdiff(
+    d1,
+    d2->inode->snapid,
+    &(out->dir_entry),
+    &snapid);
+  if (r >= 0) {
+    // converting snapid_t to uint64_t to avoid snapid_t exposure
+    out->snapid = snapid;
+  }
+  return r;
+}
+
+extern "C" int ceph_close_snapdiff(struct ceph_snapdiff_info* snapdiff)
+{
+  if (!snapdiff->cmount || !snapdiff->cmount->is_mounted()) {
+    /* also sets errno to signal errors. */
+    errno = ENOTCONN;
+    return -errno;
+  }
+  if (snapdiff->dir_aux) {
+    ceph_closedir(snapdiff->cmount, snapdiff->dir_aux);
+  }
+  if (snapdiff->dir1) {
+    ceph_closedir(snapdiff->cmount, snapdiff->dir1);
+  }
+  snapdiff->cmount = nullptr;
+  snapdiff->dir1 = snapdiff->dir_aux = nullptr;
+  return 0;
+}
+
 extern "C" int ceph_getdents(struct ceph_mount_info *cmount, struct ceph_dir_result *dirp,
 			     char *buf, int buflen)
 {