Date: Wed, 23 Feb 2011 08:11:32 -0500 From: John Baldwin <jhb@freebsd.org> To: fs@freebsd.org Cc: "Pedro F. Giffuni" <giffunip@yahoo.com> Subject: Simple ext2fs allocation routine cleanups Message-ID: <201102230811.32864.jhb@freebsd.org>
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I have some small changes to ext2fs to use ffs() to simplify some of the
allocation routines. The changes compile, but I have not had time to generate
a test ext2fs file system to run-test them. If someone has some spare cycles
to setup a test file system and try them out I would appreciate it. Otherwise
I will get to it eventually. Given that this hasn't been run-tested yet, I
would not recommend using it for a production ext2fs since it may completely
trash the filesystem.
Index: ext2_alloc.c
===================================================================
--- ext2_alloc.c (revision 218951)
+++ ext2_alloc.c (working copy)
@@ -815,16 +815,12 @@
}
}
i = start + len - loc;
- map = ibp[i];
- ipref = i * NBBY;
- for (i = 1; i < (1 << NBBY); i <<= 1, ipref++) {
- if ((map & i) == 0) {
- goto gotit;
- }
+ map = ibp[i] ^ 0xff;
+ if (map == 0) {
+ printf("fs = %s\n", fs->e2fs_fsmnt);
+ panic("ext2fs_nodealloccg: block not in map");
}
- printf("fs = %s\n", fs->e2fs_fsmnt);
- panic("ext2fs_nodealloccg: block not in map");
- /* NOTREACHED */
+ ipref = i * NBBY + ffs(map);
gotit:
setbit(ibp, ipref);
EXT2_LOCK(ump);
@@ -952,7 +948,6 @@
static daddr_t
ext2_mapsearch(struct m_ext2fs *fs, char *bbp, daddr_t bpref)
{
- daddr_t bno;
int start, len, loc, i, map;
/*
@@ -977,15 +972,12 @@
}
}
i = start + len - loc;
- map = bbp[i];
- bno = i * NBBY;
- for (i = 1; i < (1 << NBBY); i <<= 1, bno++) {
- if ((map & i) == 0)
- return (bno);
+ map = bbp[i] ^ 0xff;
+ if (map == 0) {
+ printf("fs = %s\n", fs->e2fs_fsmnt);
+ panic("ext2fs_mapsearch: block not in map");
}
- printf("fs = %s\n", fs->e2fs_fsmnt);
- panic("ext2fs_mapsearch: block not in map");
- /* NOTREACHED */
+ return (i * NBBY + ffs(map));
}
/*
--
John Baldwin
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