Date: Tue, 04 Apr 2023 08:02:05 -0700 From: Cy Schubert <Cy.Schubert@cschubert.com> To: Mateusz Guzik <mjguzik@gmail.com> Cc: Cy Schubert <Cy.Schubert@cschubert.com>, Martin Matuska <mm@freebsd.org>, src-committers@freebsd.org, dev-commits-src-all@freebsd.org, dev-commits-src-main@freebsd.org Subject: Re: git: 8ee579abe09e - main - zfs: fall back if block_cloning feature is disabled Message-ID: <20230404150206.0A0512A7@slippy.cwsent.com> In-Reply-To: <CAGudoHEvGDUQkYe8LwUXgTZZa%2B6DAFXVtspCX-Mn2egDO2oc_w@mail.gmail.com> References: <202304041145.334Bjx6l035872@gitrepo.freebsd.org> <20230404141717.B976D31C@slippy.cwsent.com> <CAGudoHEvGDUQkYe8LwUXgTZZa%2B6DAFXVtspCX-Mn2egDO2oc_w@mail.gmail.com>
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In message <CAGudoHEvGDUQkYe8LwUXgTZZa+6DAFXVtspCX-Mn2egDO2oc_w@mail.gmail.c om> , Mateusz Guzik writes: > On 4/4/23, Cy Schubert <Cy.Schubert@cschubert.com> wrote: > > In message <202304041145.334Bjx6l035872@gitrepo.freebsd.org>, Martin > > Matuska wr > > ites: > >> The branch main has been updated by mm: > >> > >> URL: > >> https://cgit.FreeBSD.org/src/commit/?id=8ee579abe09ec1fe15c588fc9a08370b > >> 83b81cd6 > >> > >> commit 8ee579abe09ec1fe15c588fc9a08370b83b81cd6 > >> Author: Martin Matuska <mm@FreeBSD.org> > >> AuthorDate: 2023-04-04 11:40:41 +0000 > >> Commit: Martin Matuska <mm@FreeBSD.org> > >> CommitDate: 2023-04-04 11:43:34 +0000 > >> > >> zfs: fall back if block_cloning feature is disabled > >> > >> If block_cloning is disabled, or other errors from zfs_clone_range() > >> return an EXDEV we should fall back to vn_generic_copy_file_range(). > >> > >> This fixes issues when copying files on the same dataset with > >> block_cloning disabled. > >> > >> Upstreamed as pull request to OpenZFS. > >> > >> Reviewed by: Mateusz Guzik <mjguzik@gmail.com> > >> OpenZFS pull request: 14713 > >> --- > >> .../openzfs/module/os/freebsd/zfs/zfs_vnops_os.c | 17 > >> ++++++++++----- > >> -- > >> 1 file changed, 10 insertions(+), 7 deletions(-) > >> > >> diff --git a/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c > >> b/sys/c > >> ontrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c > >> index 97429b360a36..2cd1d27e37bc 100644 > >> --- a/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c > >> +++ b/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c > >> @@ -6243,13 +6243,6 @@ zfs_freebsd_copy_file_range(struct > >> vop_copy_file_range > >> _args *ap) > >> int error; > >> uint64_t len = *ap->a_lenp; > >> > >> - /* > >> - * TODO: If offset/length is not aligned to recordsize, use > >> - * vn_generic_copy_file_range() on this fragment. > >> - * It would be better to do this after we lock the vnodes, but then we > >> - * need something else than vn_generic_copy_file_range(). > >> - */ > >> - > >> /* Lock both vnodes, avoiding risk of deadlock. */ > >> do { > >> mp = NULL; > >> @@ -6300,6 +6293,16 @@ unlock: > >> if (mp != NULL) > >> vn_finished_write(mp); > >> > >> + /* > >> + * Fall back if block_cloning feature is disabled > >> + * or other EXDEV failures from zfs_vnops.c > >> + */ > >> + if (error == EXDEV) { > >> + error = vn_generic_copy_file_range(ap->a_invp, ap->a_inoffp, > >> + ap->a_outvp, ap->a_outoffp, ap->a_lenp, ap->a_flags > >> , > >> + ap->a_incred, ap->a_outcred, ap->a_fsizetd); > >> + } > >> + > >> return (error); > >> } > >> > >> > > > > This is too late to fall back. On Rick's suggestion the following makes the > > > > determination at > > zfs_freebsd_copy_file_range() entry much earlier. > > > > It's not too late, but I agree it is faster to bail out early. > > The proposed patch adds a condition which *differs* from the one in > zfs_clone_range: > if (dmu_objset_spa(inos) != dmu_objset_spa(outos)) { > zfs_exit_two(inzfsvfs, outzfsvfs, FTAG); > return (SET_ERROR(EXDEV)); > } > > ... meaning with the proposed patch the routine can still fail with > EXDEV, making zfs_freebsd_copy_file_range also do it, which must not > happen. > > That aside the code looks rather suspicious for the case where target > and source vnode are the same. iow more work is needed here. > > As the vnode is unlocked, you *can't* safely access zfsvfs_t > *outzfsvfs = ZTOZSB(outzp); in that spot in this manner -- a forced > unmount at the same time can free it. > > iow this patch does *NOT* work. > > With the committed variant the situation is damage controlled enough > that there is time to sort it out correctly. > > > diff --git a/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c > > b/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c [...] Gotcha. What you're suggesting is something more like this. Check for block_cloning and also retry should zfs_clone_range() return EXDEV for any other reason. diff --git a/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c b/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c index baa2ee5b3824..60916bfcfbc3 100644 --- a/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c +++ b/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c @@ -6239,6 +6239,9 @@ zfs_freebsd_copy_file_range(struct vop_copy_file_range_args *ap) struct vnode *invp = ap->a_invp; struct vnode *outvp = ap->a_outvp; struct mount *mp; + znode_t *outzp; + zfsvfs_t *outzfsvfs; + objset_t *outos; struct uio io; int error; uint64_t len = *ap->a_lenp; @@ -6276,6 +6279,19 @@ zfs_freebsd_copy_file_range(struct vop_copy_file_range_args *ap) } while (error == 0); if (error != 0) return (error); + + outzp = VTOZ(ap->a_outvp); + outzfsvfs = ZTOZSB(outzp); + outos = outzfsvfs->z_os; + + if (!spa_feature_is_enabled(dmu_objset_spa(outos), + SPA_FEATURE_BLOCK_CLONING)) { + error = vn_generic_copy_file_range(ap->a_invp, ap->a_inoffp, + ap->a_outvp, ap->a_outoffp, ap->a_lenp, ap->a_flags, + ap->a_incred, ap->a_outcred, ap->a_fsizetd); + goto unlock; + } + #ifdef MAC error = mac_vnode_check_write(curthread->td_ucred, ap->a_outcred, outvp); @@ -6291,6 +6307,11 @@ zfs_freebsd_copy_file_range(struct vop_copy_file_range_args *ap) error = zfs_clone_range(VTOZ(invp), ap->a_inoffp, VTOZ(outvp), ap->a_outoffp, &len, ap->a_outcred); + + if (error == EXDEV) + error = vn_generic_copy_file_range(ap->a_invp, ap->a_inoffp, + ap->a_outvp, ap->a_outoffp, ap->a_lenp, ap->a_flags, + ap->a_incred, ap->a_outcred, ap->a_fsizetd); *ap->a_lenp = (size_t)len; unlock: -- Cheers, Cy Schubert <Cy.Schubert@cschubert.com> FreeBSD UNIX: <cy@FreeBSD.org> Web: https://FreeBSD.org NTP: <cy@nwtime.org> Web: https://nwtime.org e^(i*pi)+1=0
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