From: Daniel Kobras <d.kobras@science-computing.de>
Date: Wed, 10 Apr 2013 12:25:12 +0000 (+0200)
Subject: LU-2856 mdt: Workaround for filenames w/zero hash
X-Git-Tag: 2.3.65~43
X-Git-Url: https://git.whamcloud.com/gitweb?a=commitdiff_plain;h=ed1e6b0698c1902ece59dd7d082a1ba0e4feb0d2;p=fs%2Flustre-release.git

LU-2856 mdt: Workaround for filenames w/zero hash

Zero is a valid return value of full_name_hash(), but
consumers of mlh_pdo_hash don't handle this case correctly.
Work around problems by consistently mapping zero hashes to
a different value.

Signed-off-by: Daniel Kobras <d.kobras@science-computing.de>
Change-Id: I8b2622cb9b04d9f005f8e414ad35102155820c7d
Reviewed-on: http://review.whamcloud.com/6166
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Fan Yong <fan.yong@intel.com>
---

diff --git a/lustre/mdt/mdt_handler.c b/lustre/mdt/mdt_handler.c
index 53545e0..82cfdef 100644
--- a/lustre/mdt/mdt_handler.c
+++ b/lustre/mdt/mdt_handler.c
@@ -154,6 +154,13 @@ void mdt_lock_pdo_init(struct mdt_lock_handle *lh, ldlm_mode_t lm,
         if (name != NULL && (name[0] != '\0')) {
                 LASSERT(namelen > 0);
                 lh->mlh_pdo_hash = full_name_hash(name, namelen);
+		/* XXX Workaround for LU-2856
+		 * Zero is a valid return value of full_name_hash, but several
+		 * users of mlh_pdo_hash assume a non-zero hash value. We
+		 * therefore map zero onto an arbitrary, but consistent
+		 * value (1) to avoid problems further down the road. */
+		if (unlikely(!lh->mlh_pdo_hash))
+			lh->mlh_pdo_hash = 1;
         } else {
                 LASSERT(namelen == 0);
                 lh->mlh_pdo_hash = 0ull;