On Fri, Apr 05, 2019 at 09:18:58AM -0500, Eric Sandeen wrote:
> On 3/20/19 2:37 PM, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> >
> > Remote symlink target blocks are multi-fsb objects on XFS v5 filesystems
> > because we only write one rmt header per data fork extent. For fs
> > blocksize >= 2048 we never have more than one block and therefore nobody
> > noticed, but for blocksize == 1024 this is definitely not true and leads
> > to metadump spraying error messages about symlink block crc errors.
> > Therefore, reformulate the symlink metadump into a multi-fsb dump
> > function.
> >
> > Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> Ok, thanks for the patient re-explanation on IRC, and after a bit of testing,
> even with fragmented multi-block symlinks, this does work fine.
>
> I'd kind of like to fully understand why, with a single map, it handles
> fragmented links, but for now, moving on ...
>
> Reviewed-by: Eric Sandeen <sandeen@xxxxxxxxxx>
>
> I'd like to change the struct bbmap initialization to outside the
> declaration, though, to be more in line with other similar code.
> Any heartburn over that?
>
> map.nmaps = 1;
> map.b[0].bm_bn = XFS_FSB_TO_DADDR(mp, s);
> map.b[0].bm_len = XFS_FSB_TO_BB(mp, c);
No, that's fine. Admittedly that thing I wrote is five lines longer
than it needs to be; I'll write myself a BMW, etc. Feel free to change
it. :)
--D
>
>
>
> > ---
> > db/metadump.c | 48 +++++++++++++++++++++++++++++++++++++++++-------
> > 1 file changed, 41 insertions(+), 7 deletions(-)
> >
> > diff --git a/db/metadump.c b/db/metadump.c
> > index 57216291..e0dd463f 100644
> > --- a/db/metadump.c
> > +++ b/db/metadump.c
> > @@ -1638,11 +1638,39 @@ process_dir_data_block(
> > }
> > }
> >
> > -static void
> > +static int
> > process_symlink_block(
> > - char *block)
> > + xfs_fileoff_t o,
> > + xfs_fsblock_t s,
> > + xfs_filblks_t c,
> > + typnm_t btype,
> > + xfs_fileoff_t last)
> > {
> > - char *link = block;
> > + struct bbmap map = {
> > + .nmaps = 1,
> > + .b = {
> > + {
> > + .bm_bn = XFS_FSB_TO_DADDR(mp, s),
> > + .bm_len = XFS_FSB_TO_BB(mp, c),
> > + }
> > + },
> > + };
> > + char *link;
> > + int ret = 0;
> > +
> > + push_cur();
> > + set_cur(&typtab[btype], 0, 0, DB_RING_IGN, &map);
> > + if (!iocur_top->data) {
> > + xfs_agnumber_t agno = XFS_FSB_TO_AGNO(mp, s);
> > + xfs_agblock_t agbno = XFS_FSB_TO_AGBNO(mp, s);
> > +
> > + print_warning("cannot read %s block %u/%u (%llu)",
> > + typtab[btype].name, agno, agbno, s);
> > + if (stop_on_read_error)
> > + ret = -1;
> > + goto out_pop;
> > + }
> > + link = iocur_top->data;
> >
> > if (xfs_sb_version_hascrc(&(mp)->m_sb))
> > link += sizeof(struct xfs_dsymlink_hdr);
> > @@ -1660,6 +1688,12 @@ process_symlink_block(
> > if (zlen < mp->m_sb.sb_blocksize)
> > memset(link + linklen, 0, zlen);
> > }
> > +
> > + iocur_top->need_crc = 1;
> > + ret = write_buf(iocur_top);
> > +out_pop:
> > + pop_cur();
> > + return ret;
> > }
> >
> > #define MAX_REMOTE_VALS 4095
> > @@ -1879,10 +1913,6 @@ process_single_fsb_objects(
> > }
> > iocur_top->need_crc = 1;
> > break;
> > - case TYP_SYMLINK:
> > - process_symlink_block(dp);
> > - iocur_top->need_crc = 1;
> > - break;
> > case TYP_ATTR:
> > process_attr_block(dp, o);
> > iocur_top->need_crc = 1;
> > @@ -1986,6 +2016,8 @@ is_multi_fsb_object(
> > {
> > if (btype == TYP_DIR2 && mp->m_dir_geo->fsbcount > 1)
> > return true;
> > + if (btype == TYP_SYMLINK)
> > + return true;
> > return false;
> > }
> >
> > @@ -2000,6 +2032,8 @@ process_multi_fsb_objects(
> > switch (btype) {
> > case TYP_DIR2:
> > return process_multi_fsb_dir(o, s, c, btype, last);
> > + case TYP_SYMLINK:
> > + return process_symlink_block(o, s, c, btype, last);
> > default:
> > print_warning("bad type for multi-fsb object %d", btype);
> > return -EINVAL;
> >
