kern/182570: ZFS panic in receive

[Keith White]

The following reply was made to PR kern/182570; it has been noted by GNATS.

From: Keith White <kwhite at site.uottawa.ca>
To: bug-followup at freebsd.org
Cc:  
Subject: Re: kern/182570: ZFS panic in receive
Date: Fri, 4 Oct 2013 07:56:24 -0400 (EDT)

 The following suggestion from Andrej Gapon fixes the problem for me:
 
 > ...
 > To me this looks very similar to a problem discovered and fixed in illumos some
 > time ago.  Please check if the following change improves the situation for you.
 >
 > https://github.com/avg-I/freebsd/commit/a7e7dece215bc5d00077e9c7f4db34d9e5c30659
 >
 > Raw:
 > https://github.com/avg-I/freebsd/commit/a7e7dece215bc5d00077e9c7f4db34d9e5c30659.patch
 > ...
 
 Once the patch is applied, "svn diff" gives:
 
 Index: sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu.c
 ===================================================================
 --- sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu.c	(revision 255986)
 +++ sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu.c	(working copy)
 @@ -677,6 +677,16 @@
    	if (err != 0)
    		return (err);
    	err = dmu_free_long_range_impl(os, dn, offset, length);
 +
 +	/*
 +	 * It is important to zero out the maxblkid when freeing the entire
 +	 * file, so that (a) subsequent calls to dmu_free_long_range_impl()
 +	 * will take the fast path, and (b) dnode_reallocate() can verify
 +	 * that the entire file has been freed.
 +	 */
 +	if (offset == 0 && length == DMU_OBJECT_END)
 +		dn->dn_maxblkid = 0;
 +
    	dnode_rele(dn, FTAG);
    	return (err);
    }
 Index: sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_tx.c
 ===================================================================
 --- sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_tx.c	(revision 255986)
 +++ sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_tx.c	(working copy)
 @@ -616,7 +616,7 @@
    	 */
    	if (dn->dn_datablkshift == 0) {
    		if (off != 0 || len < dn->dn_datablksz)
 -			dmu_tx_count_write(txh, off, len);
 +			dmu_tx_count_write(txh, 0, dn->dn_datablksz);
    	} else {
    		/* first block will be modified if it is not aligned */
    		if (!IS_P2ALIGNED(off, 1 << dn->dn_datablkshift))