[lustre-devel] [PATCH 47/50] lustre: llite: set default LMV hash type with 2.12 MDS

[James Simmons]

From: Lai Siyao <lai.siyao at whamcloud.com>

If default LMV hash type is CRUSH, or unset, it should be converted
to fnv_16_64, because 2.12 MDS doesn't understand this.

Fix LMV_HASH_FLAG_KNOWN to match actual known flags.

Fixes: d956d88c463f ("lustre: dne: introduce new directory hash type: "crush")
Fixes: 7d33e94b9575 ("lustre: lmv: change default hash type to crush")
WC-bug-id: https://jira.whamcloud.com/browse/LU-15502
Lustre-commit: 51c6d596d4f3e82de ("LU-15502 llite: set default LMV hash type with 2.12 MDS
Signed-off-by: Lai Siyao <lai.siyao at whamcloud.com>
Reviewed-on: https://review.whamcloud.com/46378
Reviewed-by: Andreas Dilger <adilger at whamcloud.com>
Reviewed-by: Patrick Farrell <pfarrell at whamcloud.com>
Reviewed-by: Oleg Drokin <green at whamcloud.com>
Signed-off-by: James Simmons <jsimmons at infradead.org>
---
 fs/lustre/llite/dir.c                   | 28 +++++++++++++++++++++++-----
 include/uapi/linux/lustre/lustre_user.h |  2 +-
 2 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/fs/lustre/llite/dir.c b/fs/lustre/llite/dir.c
index 4165726..cfd8184 100644
--- a/fs/lustre/llite/dir.c
+++ b/fs/lustre/llite/dir.c
@@ -469,7 +469,7 @@ static int ll_dir_setdirstripe(struct dentry *dparent, struct lmv_user_md *lump,
 		enum lmv_hash_type type = lump->lum_hash_type &
 					  LMV_HASH_TYPE_MASK;
 
-		if (type == LMV_HASH_TYPE_CRUSH ||
+		if (type >= LMV_HASH_TYPE_CRUSH ||
 		    type == LMV_HASH_TYPE_UNKNOWN)
 			lump->lum_hash_type = (lump->lum_hash_type ^ type) |
 					      LMV_HASH_TYPE_FNV_1A_64;
@@ -590,11 +590,29 @@ int ll_dir_setstripe(struct inode *inode, struct lov_user_md *lump,
 		case LOV_USER_MAGIC_COMP_V1:
 			lum_size = ((struct lov_comp_md_v1 *)lump)->lcm_size;
 			break;
-		case LMV_USER_MAGIC:
-			if (lump->lmm_magic != cpu_to_le32(LMV_USER_MAGIC))
-				lustre_swab_lmv_user_md((struct lmv_user_md *)lump);
-			lum_size = sizeof(struct lmv_user_md);
+		case LMV_USER_MAGIC: {
+			struct lmv_user_md *lmv = (struct lmv_user_md *)lump;
+
+			/* MDS < 2.14 doesn't support 'crush' hash type, and
+			 * cannot handle unknown hash if client doesn't set a
+			 * valid one. switch to fnv_1a_64.
+			 */
+			if (!(exp_connect_flags2(sbi->ll_md_exp) &
+			      OBD_CONNECT2_CRUSH)) {
+				enum lmv_hash_type type = lmv->lum_hash_type &
+							  LMV_HASH_TYPE_MASK;
+
+				if (type >= LMV_HASH_TYPE_CRUSH ||
+				    type == LMV_HASH_TYPE_UNKNOWN)
+					lmv->lum_hash_type =
+						(lmv->lum_hash_type ^ type) |
+						LMV_HASH_TYPE_FNV_1A_64;
+			}
+			if (lmv->lum_magic != cpu_to_le32(LMV_USER_MAGIC))
+				lustre_swab_lmv_user_md(lmv);
+			lum_size = sizeof(*lmv);
 			break;
+		}
 		case LOV_USER_MAGIC_SPECIFIC: {
 			struct lov_user_md_v3 *v3 =
 				(struct lov_user_md_v3 *)lump;
diff --git a/include/uapi/linux/lustre/lustre_user.h b/include/uapi/linux/lustre/lustre_user.h
index 9892fc5..3017148 100644
--- a/include/uapi/linux/lustre/lustre_user.h
+++ b/include/uapi/linux/lustre/lustre_user.h
@@ -741,7 +741,7 @@ static inline bool lmv_is_known_hash_type(__u32 type)
 #define LMV_HASH_FLAG_LAYOUT_CHANGE	\
 	(LMV_HASH_FLAG_MIGRATION | LMV_HASH_FLAG_SPLIT | LMV_HASH_FLAG_MERGE)
 
-#define LMV_HASH_FLAG_KNOWN		0xfe000000
+#define LMV_HASH_FLAG_KNOWN		0xbe000000
 
 /* both SPLIT and MIGRATION are set for directory split */
 static inline bool lmv_hash_is_splitting(__u32 hash)
-- 
1.8.3.1