From: Colin Walters <walters@verbum.org>
Date: Tue, 28 Nov 2017 11:14:29 +0000 (-0500)
Subject: lib/commit: Reuse txn dir for tmpfiles
X-Git-Tag: archive/raspbian/2022.1-3+rpi1~1^2~4^2~29^2~7
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=72304a272c7df7870ce1cafb5e97b611fa2114a7;p=ostree.git

lib/commit: Reuse txn dir for tmpfiles

This closes a race condition I was seeing with `test-concurrency.py`. If we
don't have `O_TMPFILE` (or for symlinks) we'll create temporary files;
previously these would be subject to the date-based pruning because we set the
timestamp to 0 for objects.

Having our temporary files also in the txn staging dir ensures that they're
covered by the locking we do for that directory, and it's also generally cleaner
since the lifecycle of all the temporary data for a txn is in one place.

Closes: #1352
Approved by: dbnicholson
---

diff --git a/src/libostree/ostree-repo-commit.c b/src/libostree/ostree-repo-commit.c
index e283702d..aaea0a06 100644
--- a/src/libostree/ostree-repo-commit.c
+++ b/src/libostree/ostree-repo-commit.c
@@ -51,6 +51,20 @@ commit_dest_dfd (OstreeRepo *self)
     return self->objects_dir_fd;
 }
 
+/* If we don't have O_TMPFILE, or for symlinks we'll create temporary
+ * files.  If we have a txn, use the staging dir to ensure that
+ * things are consistently locked against concurrent cleanup, and
+ * in general we have all of our data in one place.
+ */
+static int
+commit_tmp_dfd (OstreeRepo *self)
+{
+  if (self->in_transaction)
+    return self->commit_stagedir.fd;
+  else
+    return self->tmp_dir_fd;
+}
+
 /* The objects/ directory has a two-character directory prefix for checksums
  * to avoid putting lots of files in a single directory.   This technique
  * is quite old, but Git also uses it for example.
@@ -439,7 +453,7 @@ _ostree_repo_bare_content_open (OstreeRepo            *self,
   g_assert (!real->initialized);
   real->initialized = TRUE;
   g_assert (S_ISREG (mode));
-  if (!glnx_open_tmpfile_linkable_at (self->tmp_dir_fd, ".", O_WRONLY|O_CLOEXEC,
+  if (!glnx_open_tmpfile_linkable_at (commit_tmp_dfd (self), ".", O_WRONLY|O_CLOEXEC,
                                       &real->tmpf, error))
     return FALSE;
   ot_checksum_init (&real->checksum);
@@ -530,7 +544,7 @@ create_regular_tmpfile_linkable_with_content (OstreeRepo *self,
                                               GError **error)
 {
   g_auto(GLnxTmpfile) tmpf = { 0, };
-  if (!glnx_open_tmpfile_linkable_at (self->tmp_dir_fd, ".", O_WRONLY|O_CLOEXEC,
+  if (!glnx_open_tmpfile_linkable_at (commit_tmp_dfd (self), ".", O_WRONLY|O_CLOEXEC,
                                       &tmpf, error))
     return FALSE;
 
@@ -668,7 +682,7 @@ write_content_object (OstreeRepo         *self,
    *
    * We use GLnxTmpfile for regular files, and OtCleanupUnlinkat for symlinks.
    */
-  g_auto(OtCleanupUnlinkat) tmp_unlinker = { self->tmp_dir_fd, NULL };
+  g_auto(OtCleanupUnlinkat) tmp_unlinker = { commit_tmp_dfd (self), NULL };
   g_auto(GLnxTmpfile) tmpf = { 0, };
   goffset unpacked_size = 0;
   gboolean indexable = FALSE;
@@ -677,7 +691,7 @@ write_content_object (OstreeRepo         *self,
     {
       /* This will not be hit for bare-user or archive */
       g_assert (self->mode == OSTREE_REPO_MODE_BARE || self->mode == OSTREE_REPO_MODE_BARE_USER_ONLY);
-      if (!_ostree_make_temporary_symlink_at (self->tmp_dir_fd,
+      if (!_ostree_make_temporary_symlink_at (commit_tmp_dfd (self),
                                               g_file_info_get_symlink_target (file_info),
                                               &tmp_unlinker.path,
                                               cancellable, error))
@@ -700,7 +714,7 @@ write_content_object (OstreeRepo         *self,
       if (self->generate_sizes)
         indexable = TRUE;
 
-      if (!glnx_open_tmpfile_linkable_at (self->tmp_dir_fd, ".", O_WRONLY|O_CLOEXEC,
+      if (!glnx_open_tmpfile_linkable_at (commit_tmp_dfd (self), ".", O_WRONLY|O_CLOEXEC,
                                           &tmpf, error))
         return FALSE;
       temp_out = g_unix_output_stream_new (tmpf.fd, FALSE);
@@ -790,14 +804,14 @@ write_content_object (OstreeRepo         *self,
            * Note, this does not apply for bare-user repos, as they store symlinks
            * as regular files.
            */
-          if (G_UNLIKELY (fchownat (self->tmp_dir_fd, tmp_unlinker.path,
+          if (G_UNLIKELY (fchownat (tmp_unlinker.dfd, tmp_unlinker.path,
                                     uid, gid, AT_SYMLINK_NOFOLLOW) == -1))
             return glnx_throw_errno_prefix (error, "fchownat");
 
           if (xattrs != NULL)
             {
-              ot_security_smack_reset_dfd_name (self->tmp_dir_fd, tmp_unlinker.path);
-              if (!glnx_dfd_name_set_all_xattrs (self->tmp_dir_fd, tmp_unlinker.path,
+              ot_security_smack_reset_dfd_name (tmp_unlinker.dfd, tmp_unlinker.path);
+              if (!glnx_dfd_name_set_all_xattrs (tmp_unlinker.dfd, tmp_unlinker.path,
                                                  xattrs, cancellable, error))
                 return FALSE;
             }
@@ -1039,7 +1053,7 @@ write_metadata_object (OstreeRepo         *self,
 
   /* Write the metadata to a temporary file */
   g_auto(GLnxTmpfile) tmpf = { 0, };
-  if (!glnx_open_tmpfile_linkable_at (self->tmp_dir_fd, ".", O_WRONLY|O_CLOEXEC,
+  if (!glnx_open_tmpfile_linkable_at (commit_tmp_dfd (self), ".", O_WRONLY|O_CLOEXEC,
                                       &tmpf, error))
     return FALSE;
   if (!glnx_try_fallocate (tmpf.fd, 0, len, error))