feature/changelog: Capture path for deletes

PROBLEM:
There is no way to get the path of deleted file if we
have gfid from changelog since the file is already deleted.

SOLUTION:
Do a recursive readlink on parent gfid in backend .glusterfs
path to get the complete path in I/O callpath in changelog
translator and capture it in callback.

The path captured is relative from the brick root. The field
separator used is '\0'.
e.g.,
......\0<pgfid>/bname\0<relative-path>\0<next-record>

ADDITIONAL REQUIRED CHANGES:

1. The changelog translator option called "changelog.capture-del-path"
   is introduced to enable or disable the capturing of deleted entry
   path.
   e.g.,
   gluster vol set <vol-name> changelog.capture-del-path on/off

   If capture-del-path is disabled, '\0' is captured instead of
   relative path.
   e.g.,
   ......\0<pgfid>/bname\0\0\0<next-record>

2. The minor number in the version of changelog is bumped up from v1.1
   to v1.2.

3. If recursive readlink is failed for some reason, it will capture
   \0 in place of <relative path>.
   e.g.,
   ......\0<pgfid>/bname\0\0\0<next-record>
   (same as when caputre-del-path option is disabled)

4. If bname argument passed to "resolve_pargfid_to_path" function
   is NULL and pargfid is ROOT, "." is returned. This is not the
   case with changelog, where bname is always passed. This is
   applicable to other consumers of "resolve_pargfid_to_path"
   routine.

NOTE:
   Changelog parser should consider the above new changes
   and should parse accordingly.

BUG: 1218383
Change-Id: I5d89cf4157befd207771f6c0248d2493fbf85832
Signed-off-by: Kotresh HR <khiremat@redhat.com>
Reviewed-on: http://review.gluster.org/10288
Reviewed-on: http://review.gluster.org/10535
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Tested-by: NetBSD Build System
Reviewed-by: Aravinda VK <avishwan@redhat.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

1 files changed, 85 insertions, 0 deletions

diff --git a/xlators/features/changelog/src/changelog-helpers.c b/xlators/features/changelog/src/changelog-helpers.c
index a72ad25e4bc..0a29969194e 100644
--- a/xlators/features/changelog/src/changelog-helpers.c
+++ b/xlators/features/changelog/src/changelog-helpers.c
@@ -1735,3 +1735,88 @@ err:
                 inode_unref (parent);
         return -1;
 }
+
+/*
+ * resolve_pargfid_to_path:
+ *      It converts given pargfid to path by doing recursive readlinks at the
+ * backend. If bname is given, it suffixes bname to pargfid to form the
+ * complete path else it doesn't. It allocates memory for the path and is
+ * caller's responsibility to free the same. If bname is NULL and pargfid
+ * is ROOT, then it returns "."
+ */
+
+int
+resolve_pargfid_to_path (xlator_t *this, uuid_t pargfid,
+                         char **path, char *bname)
+{
+        char             *linkname                  = NULL;
+        char             *dir_handle                = NULL;
+        char             *pgfidstr                  = NULL;
+        char             *saveptr                   = NULL;
+        ssize_t           len                       = 0;
+        int               ret                       = 0;
+        uuid_t            tmp_gfid                  = {0, };
+        changelog_priv_t *priv                      = NULL;
+        char              gpath[PATH_MAX]           = {0,};
+        char              result[PATH_MAX]          = {0,};
+        char             *dir_name                  = NULL;
+        char              pre_dir_name[PATH_MAX]    = {0,};
+
+        GF_ASSERT (this);
+        priv = this->private;
+        GF_ASSERT (priv);
+
+        if (!path || gf_uuid_is_null (pargfid)) {
+                ret = -1;
+                goto out;
+        }
+
+        if (__is_root_gfid (pargfid)) {
+                if (bname)
+                        *path = gf_strdup (bname);
+                else
+                        *path = gf_strdup (".");
+                return ret;
+        }
+
+        dir_handle = alloca (PATH_MAX);
+        linkname   = alloca (PATH_MAX);
+        (void) snprintf (gpath, PATH_MAX, "%s/.glusterfs/",
+                         priv->changelog_brick);
+
+        while (!(__is_root_gfid (pargfid))) {
+                snprintf (dir_handle, PATH_MAX, "%s/%02x/%02x/%s", gpath,
+                          pargfid[0], pargfid[1], uuid_utoa (pargfid));
+
+                len = readlink (dir_handle, linkname, PATH_MAX);
+                if (len < 0) {
+                        gf_log (this->name, GF_LOG_ERROR, "could not read the "
+                                "link from the gfid handle %s (%s)", dir_handle,
+                                strerror (errno));
+                        ret = -1;
+                        goto out;
+                }
+
+                linkname[len] = '\0';
+
+                pgfidstr = strtok_r (linkname + strlen("../../00/00/"), "/",
+                                     &saveptr);
+                dir_name = strtok_r (NULL, "/", &saveptr);
+
+                strncpy (result, dir_name, PATH_MAX);
+                strncat (result, "/", 1);
+                strncat (result, pre_dir_name, PATH_MAX);
+                strncpy (pre_dir_name, result, PATH_MAX);
+
+                gf_uuid_parse (pgfidstr, tmp_gfid);
+                gf_uuid_copy (pargfid, tmp_gfid);
+        }
+
+        if (bname)
+                strncat (result, bname, PATH_MAX);
+
+        *path = gf_strdup (result);
+
+out:
+        return ret;
+}