On Mon, Oct 21, 2019 at 11:33:59AM -0500, Eric Sandeen wrote:
> On 9/25/19 4:36 PM, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> >
> > When we report media errors, we should tell the administrator the file
> > offset and length of the bad region, not just the offset of the entire
> > file extent record that overlaps a bad region.
> >
> > Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> > ---
> > libfrog/bitmap.c | 37 +++++++++++++++++++++++++++++++++++++
> > libfrog/bitmap.h | 2 ++
> > scrub/phase6.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++-----
> > 3 files changed, 86 insertions(+), 5 deletions(-)
> >
> >
> > diff --git a/libfrog/bitmap.c b/libfrog/bitmap.c
> > index a75d085a..6a88ef48 100644
> > --- a/libfrog/bitmap.c
> > +++ b/libfrog/bitmap.c
> > @@ -339,6 +339,43 @@ bitmap_iterate(
> > }
> > #endif
> >
> > +/* Iterate the set regions of part of this bitmap. */
> > +int
> > +bitmap_iterate_range(
> > + struct bitmap *bmap,
> > + uint64_t start,
> > + uint64_t length,
> > + int (*fn)(uint64_t, uint64_t, void *),
> > + void *arg)
> > +{
> > + struct avl64node *firstn;
> > + struct avl64node *lastn;
> > + struct avl64node *pos;
> > + struct avl64node *n;
> > + struct avl64node *l;
> > + struct bitmap_node *ext;
> > + int ret = 0;
> > +
> > + pthread_mutex_lock(&bmap->bt_lock);
> > +
> > + avl64_findranges(bmap->bt_tree, start, start + length, &firstn,
> > + &lastn);
> > +
> > + if (firstn == NULL && lastn == NULL)
> > + goto out;
> > +
> > + avl_for_each_range_safe(pos, n, l, firstn, lastn) {
> > + ext = container_of(pos, struct bitmap_node, btn_node);
> > + ret = fn(ext->btn_start, ext->btn_length, arg);
> > + if (ret)
> > + break;
> > + }
> > +
> > +out:
> > + pthread_mutex_unlock(&bmap->bt_lock);
> > + return ret;
> > +}
> > +
> > /* Do any bitmap extents overlap the given one? (locked) */
> > static bool
> > __bitmap_test(
> > diff --git a/libfrog/bitmap.h b/libfrog/bitmap.h
> > index 759386a8..043b77ee 100644
> > --- a/libfrog/bitmap.h
> > +++ b/libfrog/bitmap.h
> > @@ -16,6 +16,8 @@ void bitmap_free(struct bitmap **bmap);
> > int bitmap_set(struct bitmap *bmap, uint64_t start, uint64_t length);
> > int bitmap_iterate(struct bitmap *bmap, int (*fn)(uint64_t, uint64_t, void *),
> > void *arg);
> > +int bitmap_iterate_range(struct bitmap *bmap, uint64_t start, uint64_t length,
> > + int (*fn)(uint64_t, uint64_t, void *), void *arg);
> > bool bitmap_test(struct bitmap *bmap, uint64_t start,
> > uint64_t len);
> > bool bitmap_empty(struct bitmap *bmap);
> > diff --git a/scrub/phase6.c b/scrub/phase6.c
> > index 1edd98af..a16ad114 100644
> > --- a/scrub/phase6.c
> > +++ b/scrub/phase6.c
> > @@ -111,6 +111,41 @@ xfs_decode_special_owner(
> >
> > /* Routines to translate bad physical extents into file paths and offsets. */
> >
> > +struct badfile_report {
> > + struct scrub_ctx *ctx;
> > + const char *descr;
> > + struct xfs_bmap *bmap;
> > +};
> > +
> > +/* Report on bad extents found during a media scan. */
> > +static int
> > +report_badfile(
> > + uint64_t start,
> > + uint64_t length,
> > + void *arg)
> > +{
> > + struct badfile_report *br = arg;
> > + unsigned long long bad_offset;
> > + unsigned long long bad_length;
> > +
> > + /* Clamp the bad region to the file mapping. */
> > + if (start < br->bmap->bm_physical) {
> > + length -= br->bmap->bm_physical - start;
> > + start = br->bmap->bm_physical;
> > + }
> > + length = min(length, br->bmap->bm_length);
> > +
> > + /* Figure out how far into the bmap is the bad mapping and report it. */
> > + bad_offset = start - br->bmap->bm_physical;
> > + bad_length = min(start + length,
> > + br->bmap->bm_physical + br->bmap->bm_length) - start;
> > +
> > + str_error(br->ctx, br->descr,
> > +_("media error at data offset %llu length %llu."),
> > + br->bmap->bm_offset + bad_offset, bad_length);
> > + return 0;
> > +}
> > +
> > /* Report if this extent overlaps a bad region. */
> > static bool
> > report_data_loss(
> > @@ -122,8 +157,14 @@ report_data_loss(
> > struct xfs_bmap *bmap,
> > void *arg)
> > {
> > + struct badfile_report br = {
> > + .ctx = ctx,
> > + .descr = descr,
> > + .bmap = bmap,
> > + };
> > struct media_verify_state *vs = arg;
> > struct bitmap *bmp;
> > + int ret;
> >
> > /* Only report errors for real extents. */
> > if (bmap->bm_flags & (BMV_OF_PREALLOC | BMV_OF_DELALLOC))
> > @@ -134,11 +175,12 @@ report_data_loss(
> > else
> > bmp = vs->d_bad;
> >
> > - if (!bitmap_test(bmp, bmap->bm_physical, bmap->bm_length))
> > - return true;
> > -
> > - str_error(ctx, descr,
> > -_("offset %llu failed read verification."), bmap->bm_offset);
> > + ret = bitmap_iterate_range(bmp, bmap->bm_physical, bmap->bm_length,
> > + report_badfile, &br);
> > + if (ret) {
> > + str_liberror(ctx, ret, descr);
> > + return false;
>
> So related to the prior question; why does changing the way we report a
> media error in a file change the flow with a "return false" here?
The bitmap iteration itself failed (since report_badfile never returns
false), which means it hit a runtime error and the program should exit.
(Granted, bitmap iteration never fails, so this is merely defensive
programming.)
--D
> > + }
> > return true;
> > }
> >
> >
