On Sat, Mar 03, 2018 at 08:59:50AM -0500, Brian Foster wrote: > On Fri, Mar 02, 2018 at 08:12:07AM -0500, Brian Foster wrote: > > On Thu, Mar 01, 2018 at 12:55:41PM -0800, Darrick J. Wong wrote: > > > On Thu, Mar 01, 2018 at 12:28:33PM -0500, Brian Foster wrote: > > > > On Wed, Feb 28, 2018 at 03:20:32PM -0800, Darrick J. Wong wrote: > > > > > On Wed, Feb 28, 2018 at 05:43:51PM -0500, Brian Foster wrote: > > > > > > On Tue, Feb 27, 2018 at 01:03:13PM -0800, Darrick J. Wong wrote: > > > > > > > On Tue, Feb 27, 2018 at 02:35:49PM -0500, Brian Foster wrote: > > > > > > > > On Thu, Feb 22, 2018 at 06:00:15PM -0800, Darrick J. Wong wrote: > > > > > > > > > From: Darrick J. Wong <darrick.wong@xxxxxxxxxx> > ... > > > Going forward, I want the number of unpacked kernels to decrease as > > > quickly as possible. I understand that distro kernel maintainers are > > > not willing to apply the packing patch to their kernel until we come up > > > with a smooth transition path. > > > > > > > I agree wrt to upstream, but note that I don't anticipate including the > > padding fix downstream any time soon. > > > > > I don't want to support fixing agfls to be 118 units long on 64-bit > > > unpacked kernels and 119 units long on 32-bit unpacked kernels, and I > > > only want to support the packed kernels with their 119 unit long agfls. > > > An AGFL that starts at 0 and ends at flcount-1 is compatible with packed > > > and unpacked kernels, so the v2 patch I sent last night removes the > > > delicate per-case surgery in favor of a new strategy where the mount > > > time and unmount time helpers both look for agfl configurationss that > > > are known to cause problems, and solves them all with the same solution: > > > moving the agfl list towards the start of the block. > > > > > > > The purpose of the patch I sent was not for upstream unpacked support > > going forward. Upstream has clearly moved forward with the packed > > format. The goal of the patch was to explore a single/generic patch that > > could be merged upstream/downstream and handle compatibility cleanly. > > > > FWIW, here's a new variant of a bidirectional fixup. It's refactored and > polished up a bit into a patch. It basically inspects the agf when first > read for any evidence that the on-disk fields reflect a size mismatch > with the current kernel and sets a flag if so. agfl gets/puts check the > flag and thus the first transaction that attempts to modify a mismatched > agfl swaps a block into or out of the gap slot appropriately. > > This avoids the need for any new transactions or mount time scan and the > (downstream motivated) packed -> unpacked case is only 10 or so lines of > additional code. Only spot tested, but I _think_ it covers all of the > cases. Hm? Just from a quick glance this looks like a reasonable way to fix the agfl wrapping to whatever the running kernel expects. I tried feeding it to the xfstest I wrote to exercise my agfl fixer[1], but even with changing the test to fill the fs to enospc and delete everything I couldn't get it to trigger reliably. [1] https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfstests-dev.git/commit/?h=djwong-experimental&id=f085bb09c839da69daf921da33f5d13c80c9f165 --D > Brian > > --- 8< --- > > diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c > index c02781a4c091..1cbf80d8481f 100644 > --- a/fs/xfs/libxfs/xfs_alloc.c > +++ b/fs/xfs/libxfs/xfs_alloc.c > @@ -2053,6 +2053,115 @@ xfs_alloc_space_available( > return true; > } > > +static int > +xfs_agfl_ondisk_size( > + struct xfs_mount *mp, > + int first, > + int last, > + int count) > +{ > + int active = count; > + int agfl_size = XFS_AGFL_SIZE(mp); > + > + if (count && last >= first) > + active = last - first + 1; > + else if (count) > + active = agfl_size - first + last + 1; > + > + if (active == count + 1) > + return agfl_size - 1; > + if (active == count - 1 || first == agfl_size || last == agfl_size) > + return agfl_size + 1; > + > + ASSERT(active == count); > + return agfl_size; > +} > + > +static bool > +xfs_agfl_need_padfix( > + struct xfs_mount *mp, > + struct xfs_agf *agf) > +{ > + int f = be32_to_cpu(agf->agf_flfirst); > + int l = be32_to_cpu(agf->agf_fllast); > + int c = be32_to_cpu(agf->agf_flcount); > + > + return xfs_agfl_ondisk_size(mp, f, l, c) != XFS_AGFL_SIZE(mp); > +} > + > +static int > +xfs_agfl_check_padfix( > + struct xfs_trans *tp, > + struct xfs_buf *agbp, > + struct xfs_buf *agflbp, > + struct xfs_perag *pag) > +{ > + struct xfs_mount *mp = tp->t_mountp; > + struct xfs_agf *agf = XFS_BUF_TO_AGF(agbp); > + __be32 *agfl_bno = XFS_BUF_TO_AGFL_BNO(mp, agflbp); > + int agfl_size = XFS_AGFL_SIZE(mp); > + int ofirst, olast, osize; > + int nfirst, nlast; > + int logflags = 0; > + int startoff = 0; > + > + if (!pag->pagf_needpadfix) > + return 0; > + > + ofirst = nfirst = be32_to_cpu(agf->agf_flfirst); > + olast = nlast = be32_to_cpu(agf->agf_fllast); > + osize = xfs_agfl_ondisk_size(mp, ofirst, olast, pag->pagf_flcount); > + > + /* > + * If the on-disk agfl is smaller than what the kernel expects, the > + * last slot of the on-disk agfl is a gap with bogus data. Move the > + * first valid block into the gap and bump the pointer. > + */ > + if (osize < agfl_size) { > + ASSERT(pag->pagf_flcount != 0); > + agfl_bno[agfl_size - 1] = agfl_bno[ofirst]; > + startoff = (char *) &agfl_bno[agfl_size - 1] - (char *) agflbp->b_addr; > + nfirst++; > + goto done; > + } > + > + /* > + * Otherwise, the on-disk agfl is larger than what the current kernel > + * expects. If empty, just fix up the first and last pointers. If not, > + * move the inaccessible block to the end of the valid range. > + */ > + nfirst = do_mod(nfirst, agfl_size); > + if (pag->pagf_flcount == 0) { > + nlast = (nfirst == 0 ? agfl_size - 1 : nfirst - 1); > + goto done; > + } > + if (nlast != agfl_size) > + nlast++; > + nlast = do_mod(nlast, agfl_size); > + agfl_bno[nlast] = agfl_bno[osize - 1]; > + startoff = (char *) &agfl_bno[nlast] - (char *) agflbp->b_addr; > + > +done: > + if (nfirst != ofirst) { > + agf->agf_flfirst = cpu_to_be32(nfirst); > + logflags |= XFS_AGF_FLFIRST; > + } > + if (nlast != olast) { > + agf->agf_fllast = cpu_to_be32(nlast); > + logflags |= XFS_AGF_FLLAST; > + } > + if (startoff) { > + xfs_trans_buf_set_type(tp, agflbp, XFS_BLFT_AGFL_BUF); > + xfs_trans_log_buf(tp, agflbp, startoff, > + startoff + sizeof(xfs_agblock_t) - 1); > + } > + if (logflags) > + xfs_alloc_log_agf(tp, agbp, logflags); > + > + pag->pagf_needpadfix = false; > + return 0; > +} > + > /* > * Decide whether to use this allocation group for this allocation. > * If so, fix up the btree freelist's size. > @@ -2258,6 +2367,12 @@ xfs_alloc_get_freelist( > if (error) > return error; > > + pag = xfs_perag_get(mp, be32_to_cpu(agf->agf_seqno)); > + error = xfs_agfl_check_padfix(tp, agbp, agflbp, pag); > + if (error) { > + xfs_perag_put(pag); > + return error; > + } > > /* > * Get the block number and update the data structures. > @@ -2269,7 +2384,6 @@ xfs_alloc_get_freelist( > if (be32_to_cpu(agf->agf_flfirst) == XFS_AGFL_SIZE(mp)) > agf->agf_flfirst = 0; > > - pag = xfs_perag_get(mp, be32_to_cpu(agf->agf_seqno)); > be32_add_cpu(&agf->agf_flcount, -1); > xfs_trans_agflist_delta(tp, -1); > pag->pagf_flcount--; > @@ -2376,11 +2490,18 @@ xfs_alloc_put_freelist( > if (!agflbp && (error = xfs_alloc_read_agfl(mp, tp, > be32_to_cpu(agf->agf_seqno), &agflbp))) > return error; > + > + pag = xfs_perag_get(mp, be32_to_cpu(agf->agf_seqno)); > + error = xfs_agfl_check_padfix(tp, agbp, agflbp, pag); > + if (error) { > + xfs_perag_put(pag); > + return error; > + } > + > be32_add_cpu(&agf->agf_fllast, 1); > if (be32_to_cpu(agf->agf_fllast) == XFS_AGFL_SIZE(mp)) > agf->agf_fllast = 0; > > - pag = xfs_perag_get(mp, be32_to_cpu(agf->agf_seqno)); > be32_add_cpu(&agf->agf_flcount, 1); > xfs_trans_agflist_delta(tp, 1); > pag->pagf_flcount++; > @@ -2588,6 +2709,7 @@ xfs_alloc_read_agf( > pag->pagb_count = 0; > pag->pagb_tree = RB_ROOT; > pag->pagf_init = 1; > + pag->pagf_needpadfix = xfs_agfl_need_padfix(mp, agf); > } > #ifdef DEBUG > else if (!XFS_FORCED_SHUTDOWN(mp)) { > diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h > index e0792d036be2..78a6377a9b38 100644 > --- a/fs/xfs/xfs_mount.h > +++ b/fs/xfs/xfs_mount.h > @@ -353,6 +353,7 @@ typedef struct xfs_perag { > char pagi_inodeok; /* The agi is ok for inodes */ > uint8_t pagf_levels[XFS_BTNUM_AGF]; > /* # of levels in bno & cnt btree */ > + bool pagf_needpadfix; > uint32_t pagf_flcount; /* count of blocks in freelist */ > xfs_extlen_t pagf_freeblks; /* total free blocks */ > xfs_extlen_t pagf_longest; /* longest free space */ > -- > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
