Date: Mon, 10 Feb 2003 13:31:48 +1100 From: Tim Robbins <tjr@freebsd.org> To: Mike Makonnen <mtm@identd.net> Cc: Poul-Henning Kamp <phk@phk.freebsd.dk>, current@freebsd.org Subject: Re: MSDOSFS wastes 256k when nothing is mounted! Message-ID: <20030210133148.A17199@dilbert.robbins.dropbear.id.au> In-Reply-To: <20030209230848.VZI7113.pop015.verizon.net@kokeb.ambesa.net>; from mtm@identd.net on Sun, Feb 09, 2003 at 06:08:47PM -0500 References: <31456.1044819599@critter.freebsd.dk> <20030209230848.VZI7113.pop015.verizon.net@kokeb.ambesa.net>
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On Sun, Feb 09, 2003 at 06:08:47PM -0500, Mike Makonnen wrote:
> How about the attached?
>
> It's only partially tested since it seems I can't mount any msdos floppies (both
> on this _and_ my previous kernel).
> Index: sys/fs/msdosfs/msdosfs_denode.c
> ===================================================================
> RCS file: /home/ncvs/src/sys/fs/msdosfs/msdosfs_denode.c,v
> retrieving revision 1.67
> diff -u -r1.67 msdosfs_denode.c
> --- sys/fs/msdosfs/msdosfs_denode.c 21 Jan 2003 08:55:46 -0000 1.67
> +++ sys/fs/msdosfs/msdosfs_denode.c 9 Feb 2003 22:14:41 -0000
> @@ -73,6 +73,12 @@
> static u_long dehash; /* size of hash table - 1 */
> #define DEHASH(dev, dcl, doff) (dehashtbl[(minor(dev) + (dcl) + (doff) /
> \ sizeof(struct direntry)) & dehash])
> +#define DEHASH_INIT do {\
> + if (dehashtbl == NULL) {\
> + dehashtbl = hashinit(desiredvnodes/2, M_MSDOSFSMNT, &dehash);\
> + KASSERT(dehashtbl != NULL, "msdosfs dehashtbl == NULL");\
> + }\
> + } while (0)
> static struct mtx dehash_mtx;
>
> union _qcvt {
[...]
> @@ -130,6 +138,7 @@
>
> loop:
> mtx_lock(&dehash_mtx);
> + DEHASH_INIT;
> for (dep = DEHASH(dev, dirclust, diroff); dep; dep = dep->de_next) {
> if (dirclust == dep->de_dirclust
> && diroff == dep->de_diroffset
hashinit() can sleep, and I don't think it's safe to sleep here
(msdosfs_hashget() and msdosfs_hashins()) with dehash_mtx and
sometimes a vnode lock held.
It might be better to initialise the table the first time an
msdosfs filesystem is mounted.
Tim
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