cluster/ec: fix SHD crash for null gfid's

When the self-heal daemon is doing a full sweep it uses readdirp to
get extra stat information from each file. This information is
obtained in two steps by the posix xlator: first the directory is
read to get the entries and then each entry is stated to get additional
info. Between these two steps, it's possible that the file is removed
by the user, so we'll get an error, leaving stat info empty.

EC's heal daemon was using the gfid blindly, causing an assert failure
when protocol/client was trying to encode the gfid.

To fix the problem a check has been added. If we detect a null gfid, we
simply ignore it and continue healing.

Change-Id: I2e4acdcecd0b6951055e50d1c37d686a2186a228
BUG: 1558016
Signed-off-by: Xavi Hernandez <xhernandez@redhat.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/xlators/cluster/ec/src/ec-heald.c b/xlators/cluster/ec/src/ec-heald.c
index a703379a59b..65d8b5c4284 100644
--- a/xlators/cluster/ec/src/ec-heald.c
+++ b/xlators/cluster/ec/src/ec-heald.c
@@ -301,6 +301,14 @@ ec_shd_full_heal (xlator_t *subvol, gf_dirent_t *entry, loc_t *parent,
         if (!ec->shd.enabled)
                 return -EBUSY;
 
+        if (gf_uuid_is_null(entry->d_stat.ia_gfid)) {
+                /* It's possible that an entry has been removed just after
+                 * being seen in a directory but before getting its stat info.
+                 * In this case we'll receive a NULL gfid here. Since the file
+                 * doesn't exist anymore, we can safely ignore it. */
+                return 0;
+        }
+
         loc.parent = inode_ref (parent->inode);
         loc.name   = entry->d_name;
         gf_uuid_copy (loc.gfid, entry->d_stat.ia_gfid);