PERFORCE change 189657 for review

[Zheng Liu]

http://p4web.freebsd.org/@@189657?ac=10

Change 189657 by lz at freebsd-dev on 2011/03/07 10:38:51

	       Improve sweep loop in ext2_clusteralloc() like in ffs.

Affected files ...

.. //depot/projects/soc2010/extfs/src/sys/fs/ext2fs/ext2_alloc.c#36 edit

Differences ...

==== //depot/projects/soc2010/extfs/src/sys/fs/ext2fs/ext2_alloc.c#36 (text+ko) ====

@@ -1309,16 +1309,13 @@
         int error, i, got, run;
         char *bbp;
         daddr_t bno;
+        int bit, map;
+        unsigned char *mapp;
 
         fs = ip->i_e2fs;
         ump = ip->i_ump;
 
-        /*
-         * TODO: we need to define a new member in m_ext2fs structure
-         * to save max cluster. But for simplicity, we assume that the
-         * max cluster is equal to the number of blocks per group.
-         */
-        if (fs->e2fs_gd[cg].ext2bgd_nbfree < len)
+        if (fs->e2fs_maxcluster[cg] < len)
                 return (0);
 
         EXT2_UNLOCK(ump);
@@ -1340,25 +1337,35 @@
                 bpref = 0;
         if (bpref != 0)
                 bpref = dtogd(fs, bpref);
-
+        mapp = &bbp[bpref / NBBY];
+        map = *mapp++;
+        bit = 1 << (bpref % NBBY);
         for (run = 0, got = bpref; got < fs->e2fs_bpg; got++) {
-                if (!isclr(bbp, got))
+                if (!((map & bit) == 0)) {
                         run = 0;
-                else {
+                } else {
                         run++;
                         if (run == len)
                                 break;
                 }
+                if ((got & (NBBY - 1)) != (NBBY - 1)) {
+                        bit <<= 1;
+                } else {
+                        map = *mapp++;
+                        bit = 1;
+                }
         }
 
         if (got >= fs->e2fs_bpg)
                 goto fail_lock;
+
         /*
          * Allocate the cluster that we have found.
          */
         for (i = 1; i <= len; i++)
                 if (!isclr(bbp, got - run + i))
                         panic("ext2_clusteralloc: map mismatch");
+                
         bno = got - run + 1;
         if (bno >= fs->e2fs_bpg)
                 panic("ext2_clusteralloc: allocated out of group");