On Tue, Apr 19, 2022 at 08:47:50AM -0700, Darrick J. Wong wrote:
> On Tue, Apr 19, 2022 at 02:19:51PM +0200, Andrey Albershteyn wrote:
> > Changing the interpretation type of data under the cursor moves the
> > cursor to the beginning of BB cluster. When cursor is set to an
> > inode the cursor is offset in BB buffer. However, this offset is not
> > considered when type of the data is changed - the cursor points to
> > the beginning of BB buffer. For example:
> >
> > $ xfs_db -c "inode 131" -c "daddr" -c "type text" \
> > -c "daddr" /dev/sdb1
> > current daddr is 131
> > current daddr is 128
> >
> > Signed-off-by: Andrey Albershteyn <aalbersh@xxxxxxxxxx>
> > ---
> > db/io.c | 4 ++++
> > 1 file changed, 4 insertions(+)
> >
> > diff --git a/db/io.c b/db/io.c
> > index df97ed91..107f2e11 100644
> > --- a/db/io.c
> > +++ b/db/io.c
> > @@ -589,6 +589,7 @@ set_iocur_type(
> > const typ_t *type)
> > {
> > int bb_count = 1; /* type's size in basic blocks */
> > + int boff = iocur_top->boff;
>
> Nit: Please line up the variable names.
sure ;)
>
> >
> > /*
> > * Inodes are special; verifier checks all inodes in the chunk, the
> > @@ -613,6 +614,9 @@ set_iocur_type(
> > bb_count = BTOBB(byteize(fsize(type->fields,
> > iocur_top->data, 0, 0)));
> > set_cur(type, iocur_top->bb, bb_count, DB_RING_IGN, NULL);
> > + iocur_top->boff = boff;
> > + iocur_top->off = ((xfs_off_t)iocur_top->bb << BBSHIFT) + boff;
> > + iocur_top->data = (void *)((char *)iocur_top->buf + boff);
>
> It seems reasonable to me to preserve the io cursor's boff when we're
> setting /only/ the buffer type, but this function and off_cur() could
> share these three lines of code that (re)set boff/off/data.
>
> Alternately, I guess you could just call off_cur(boff, BBTOB(bb_count))
> here.
This won't pass the second condition in off_cur(). I suppose the
purpose of off_cur() was to shift io cursor in BB buffer. But
changing the type changes the blen which could be smaller (e.g.
inode blen == 32 -> text blen == 1). Anyway, will try to come up
with a meaningful name for this 3 lines function :)
I think the other solution could be to set boff in set_cur(), but
this will require more refactoring and I suppose this is the only
place where newly added argument would be used.
>
> --D
>
> > }
> >
> > static void
> > --
> > 2.27.0
> >
>
--
- Andrey
