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Date: Sun, 16 Oct 2005 15:44:48 -0700 (PDT)
From: Matthew Dillon <dillon@apollo.backplane.com>
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Cc: 
Subject: Re: [PANIC] ufs_dirbad: bad dir
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    Ach.  sigh.  Another false alarm.  Sorry.  The code is fine.  It's
    because the 'end' block is calculated inclusively, e.g.
    end_lbn = start_lbn + len - 1.  I'm still investigating it.

    There is a bug if the range reallocblks is called with spans
    more then two blockmaps, but I don't think that case can occur in real
    life due to limitations in the range passed by the caller.  Probably
    worth a KASSERT, though.

					-Matt
					Matthew Dillon 
					<dillon@backplane.com>

:        /*
:         * If the block range spans two block maps, get the second map.
:         */
:        if (end_lvl == 0 || (idp = &end_ap[end_lvl - 1])->in_off + 1 >= len) {
:                ssize = len;
:        } else {
:#ifdef DIAGNOSTIC
:                if (start_ap[start_lvl-1].in_lbn == idp->in_lbn)
:                        panic("ffs_reallocblk: start == end");
:#endif
:                ssize = len - (idp->in_off + 1);
:			^^^^^^^^^^^^^^^^^^^^^
:			This doesn't look right.  It kinda seems to me
:			that it should be (len - idp->in_off).
:
:
:                if (bread(vp, idp->in_lbn, (int)fs->fs_bsize, &ebp))
:                        goto fail;
:                ebap = (ufs_daddr_t *)ebp->b_data;
:        }
:
:    I went through about 3 or 4 false alarms earlier today, and this could
:    be another one.   But if it is wrong it would fit the symptoms....
:    the first indirect block in the inode getting blown to bits.
:
:					-Matt
:					Matthew Dillon