Date: Thu, 24 Feb 2000 01:48:14 +0000 From: Ian Dowse <iedowse@maths.tcd.ie> To: Matthew Dillon <dillon@apollo.backplane.com> Cc: freebsd-current@freebsd.org Subject: Re: ffs_blkfree: freeing free block (was Re: Panic (pmap)) Message-ID: <200002240148.aa34053@salmon.maths.tcd.ie> In-Reply-To: Your message of "Wed, 23 Feb 2000 22:35:29 GMT." <200002232235.aa22335@salmon.maths.tcd.ie>
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In message <200002232235.aa22335@salmon.maths.tcd.ie>, Ian Dowse writes:
>
>The fix should be relatively straightforward - either the code should
>avoid linking new indirection blocks until all allocations succeed,
>or it should back out the changes on failure.
Here's one patch that seems to fix the problem. It may not be the best
approach though?
Ian
--- ffs_balloc.c.orig Thu Feb 24 00:44:32 2000
+++ ffs_balloc.c Thu Feb 24 01:45:46 2000
@@ -71,7 +71,7 @@
int flags;
struct fs *fs;
ufs_daddr_t nb;
- struct buf *bp, *nbp;
+ struct buf *bp, *nbp, *allocbp;
struct vnode *vp;
struct indir indirs[NIADDR + 2];
ufs_daddr_t newb, *bap, pref;
@@ -197,6 +197,7 @@
--num;
nb = ip->i_ib[indirs[0].in_off];
allocib = NULL;
+ allocbp = NULL;
allocblk = allociblk;
if (nb == 0) {
pref = ffs_blkpref(ip, lbn, 0, (ufs_daddr_t *)0);
@@ -272,6 +273,17 @@
}
}
bap[indirs[i - 1].in_off] = nb;
+ if (allocib == NULL) {
+ /*
+ * Writing bp would link in the newly allocated
+ * blocks; hold off in case of allocation failure
+ * later.
+ */
+ allocib = &bap[indirs[i - 1].in_off];
+ allocbp = bp;
+ continue;
+ }
+
/*
* If required, write synchronously, otherwise use
* delayed write.
@@ -316,8 +328,7 @@
bp->b_flags |= B_CLUSTEROK;
bdwrite(bp);
}
- *ap->a_bpp = nbp;
- return (0);
+ goto success;
}
brelse(bp);
if (flags & B_CLRBUF) {
@@ -330,6 +341,22 @@
nbp = getblk(vp, lbn, fs->fs_bsize, 0, 0);
nbp->b_blkno = fsbtodb(fs, nb);
}
+success:
+ if (allocbp != NULL) {
+ /*
+ * It is safe to write allocbp now.
+ *
+ * If required, write synchronously, otherwise use
+ * delayed write.
+ */
+ if (flags & B_SYNC) {
+ bwrite(allocbp);
+ } else {
+ if (allocbp->b_bufsize == fs->fs_bsize)
+ allocbp->b_flags |= B_CLUSTEROK;
+ bdwrite(allocbp);
+ }
+ }
*ap->a_bpp = nbp;
return (0);
fail:
@@ -349,8 +376,11 @@
ffs_blkfree(ip, *blkp, fs->fs_bsize);
deallocated += fs->fs_bsize;
}
- if (allocib != NULL)
+ if (allocib != NULL) {
*allocib = 0;
+ if (allocbp != NULL)
+ brelse(allocbp);
+ }
if (deallocated) {
#ifdef QUOTA
/*
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