From: Eric Mei <eric.mei@oracle.com>
Date: Mon, 6 Dec 2010 22:49:54 +0000 (-0700)
Subject: b=20563 fix fid_flatten().
X-Git-Tag: 2.0.59.0~42
X-Git-Url: https://git.whamcloud.com/?a=commitdiff_plain;h=b8e3234d406923a43bdc51e70b0a72c80b0987d3;p=fs%2Flustre-release.git

b=20563 fix fid_flatten().

r=andreas.dilger
r=di.wang
---

diff --git a/lustre/include/lustre_fid.h b/lustre/include/lustre_fid.h
index df3aa90..1c48f89 100644
--- a/lustre/include/lustre_fid.h
+++ b/lustre/include/lustre_fid.h
@@ -315,15 +315,16 @@ fid_build_pdo_res_name(const struct lu_fid *f,
 
 
 /**
- * Flatten 128-bit FID values into a 64-bit value for
- * use as an inode number.  For non-IGIF FIDs this
- * starts just over 2^32, and continues without conflict
- * until 2^64, at which point we wrap the high 32 bits
- * of the SEQ into the range where there may not be many
- * OID values in use, to minimize the risk of conflict.
+ * Flatten 128-bit FID values into a 64-bit value for use as an inode number.
+ * For non-IGIF FIDs this starts just over 2^32, and continues without
+ * conflict until 2^64, at which point we wrap the high 24 bits of the SEQ
+ * into the range where there may not be many OID values in use, to minimize
+ * the risk of conflict.
  *
- * The time between re-used inode numbers is very long -
- * 2^32 SEQ numbers, or about 2^32 client mounts. */
+ * Suppose LUSTRE_SEQ_MAX_WIDTH less than (1 << 24) which is currently true,
+ * the time between re-used inode numbers is very long - 2^40 SEQ numbers,
+ * or about 2^40 client mounts, if clients create less than 2^24 files/mount.
+ */
 static inline __u64 fid_flatten(const struct lu_fid *fid)
 {
         __u64 ino;
@@ -336,7 +337,7 @@ static inline __u64 fid_flatten(const struct lu_fid *fid)
 
         seq = fid_seq(fid);
 
-        ino = (seq << 24) + ((seq >> (64-8)) & 0xffffff0000ULL) + fid_oid(fid);
+        ino = (seq << 24) + ((seq >> 24) & 0xffffff0000ULL) + fid_oid(fid);
 
         RETURN(ino ? ino : fid_oid(fid));
 }