posix: Set correct d_type for readdirp() calls

dirent.d_type can contain the type of the directory entry. The 'd_type'
struct member in dirent is present in Linux and many BSD flavours.
However, filling d_type with correct value requires support from the
underlying filesystem. If not, d_type is set to DT_UNKNOWN. XFS added
support for d_type as part of their newer version 5 on-disk format.
However, this requires Linux >= 3.15, xfsprogs >= 3.2.0 and the bricks
to be formatted using the new format.

This patch enables posix xlator to set d_type to the right value even
when the underlying filesystem does not support it. d_type can be set
using information previously fetched by stat() on the dir entry.
This will aid FUSE applications to leverage d_type to avoid the expense
of calling lstat() if further actions depend on the type of the file.

Refer `man 3 readdir` and `man 2 getdents`

BUG: 1175711
Change-Id: Ic5a262fe4c64122726b4fae2d1bea375c559ca04
Signed-off-by: Prashanth Pai <ppai@redhat.com>
Reviewed-on: http://review.gluster.org/14095
Smoke: Gluster Build System <jenkins@build.gluster.com>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Jeff Darcy <jdarcy@redhat.com>

1 files changed, 29 insertions, 0 deletions

diff --git a/xlators/storage/posix/src/posix.c b/xlators/storage/posix/src/posix.c
index b823257d540..6cd7df54909 100644
--- a/xlators/storage/posix/src/posix.c
+++ b/xlators/storage/posix/src/posix.c
@@ -6059,6 +6059,24 @@ posix_entry_xattr_fill (xlator_t *this, inode_t *inode,
 }
 
 
+#ifdef _DIRENT_HAVE_D_TYPE
+static int
+posix_d_type_from_ia_type (ia_type_t type)
+{
+        switch (type) {
+        case IA_IFDIR:      return DT_DIR;
+        case IA_IFCHR:      return DT_CHR;
+        case IA_IFBLK:      return DT_BLK;
+        case IA_IFIFO:      return DT_FIFO;
+        case IA_IFLNK:      return DT_LNK;
+        case IA_IFREG:      return DT_REG;
+        case IA_IFSOCK:     return DT_SOCK;
+        default:            return DT_UNKNOWN;
+        }
+}
+#endif
+
+
 int
 posix_readdirp_fill (xlator_t *this, fd_t *fd, gf_dirent_t *entries, dict_t *dict)
 {
@@ -6116,6 +6134,17 @@ posix_readdirp_fill (xlator_t *this, fd_t *fd, gf_dirent_t *entries, dict_t *dic
                 entry->d_stat = stbuf;
                 if (stbuf.ia_ino)
                         entry->d_ino = stbuf.ia_ino;
+
+#ifdef _DIRENT_HAVE_D_TYPE
+                if (entry->d_type == DT_UNKNOWN && !IA_ISINVAL(stbuf.ia_type)) {
+                        /* The platform supports d_type but the underlying
+                           filesystem doesn't. We set d_type to the correct
+                           value from ia_type */
+                        entry->d_type =
+                                posix_d_type_from_ia_type (stbuf.ia_type);
+                }
+#endif
+
 		inode = NULL;
         }