Re: [PATCH 2/7] xfs: Check for per-inode extent count overflow

Chandan Babu R
2020-06-09T14:24:39Z

On Monday 8 June 2020 9:54:25 PM IST Darrick J. Wong wrote:
> On Sat, Jun 06, 2020 at 01:57:40PM +0530, Chandan Babu R wrote:
> > The following error message was noticed when a workload added one
> > million xattrs, deleted 50% of them and then inserted 400,000 new
> > xattrs.
> >
> > XFS (loop0): xfs_iflush_int: detected corrupt incore inode 131, total extents = -19916, nblocks = 102937, ptr ffff9ce33b098c00
> >
> > The error message was printed during unmounting the filesystem. The
> > value printed under "total extents" indicates that we overflowed the
> > per-inode signed 16-bit xattr extent counter.
> >
> > Instead of letting this silent corruption occur, this patch checks for
> > extent counter (both data and xattr) overflow before we assign the
> > new value to the corresponding in-memory extent counter.
> >
> > Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
> > ---
> > fs/xfs/libxfs/xfs_bmap.c | 92 +++++++++++++++++++++++++++-------
> > fs/xfs/libxfs/xfs_inode_fork.c | 29 +++++++++++
> > fs/xfs/libxfs/xfs_inode_fork.h | 1 +
> > 3 files changed, 104 insertions(+), 18 deletions(-)
> >
> > diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> > index edc63dba007f..798fca5c52af 100644
> > --- a/fs/xfs/libxfs/xfs_bmap.c
> > +++ b/fs/xfs/libxfs/xfs_bmap.c
> > @@ -906,7 +906,10 @@ xfs_bmap_local_to_extents(
> > xfs_iext_first(ifp, &icur);
> > xfs_iext_insert(ip, &icur, &rec, 0);
> >
> > - ifp->if_nextents = 1;
> > + error = xfs_next_set(ip, whichfork, 1);
> > + if (error)
> > + goto done;
>
> Are you sure that if_nextents == 0 is a precondition here? Technically
> speaking, this turns an assignment into an increment operation.

Hmm. I didn't pay attention to that. I will check and update the code
appropriately. Thanks for pointing this out.

>
> > +
> > ip->i_d.di_nblocks = 1;
> > xfs_trans_mod_dquot_byino(tp, ip,
> > XFS_TRANS_DQ_BCOUNT, 1L);
> > @@ -1594,7 +1597,10 @@ xfs_bmap_add_extent_delay_real(
> > xfs_iext_remove(bma->ip, &bma->icur, state);
> > xfs_iext_prev(ifp, &bma->icur);
> > xfs_iext_update_extent(bma->ip, state, &bma->icur, &LEFT);
> > - ifp->if_nextents--;
> > +
> > + error = xfs_next_set(bma->ip, whichfork, -1);
> > + if (error)
> > + goto done;
> >
> > if (bma->cur == NULL)
> > rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
> > @@ -1698,7 +1704,10 @@ xfs_bmap_add_extent_delay_real(
> > PREV.br_startblock = new->br_startblock;
> > PREV.br_state = new->br_state;
> > xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
> > - ifp->if_nextents++;
> > +
> > + error = xfs_next_set(bma->ip, whichfork, 1);
> > + if (error)
> > + goto done;
> >
> > if (bma->cur == NULL)
> > rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
> > @@ -1764,7 +1773,10 @@ xfs_bmap_add_extent_delay_real(
> > * The left neighbor is not contiguous.
> > */
> > xfs_iext_update_extent(bma->ip, state, &bma->icur, new);
> > - ifp->if_nextents++;
> > +
> > + error = xfs_next_set(bma->ip, whichfork, 1);
> > + if (error)
> > + goto done;
> >
> > if (bma->cur == NULL)
> > rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
> > @@ -1851,7 +1863,10 @@ xfs_bmap_add_extent_delay_real(
> > * The right neighbor is not contiguous.
> > */
> > xfs_iext_update_extent(bma->ip, state, &bma->icur, new);
> > - ifp->if_nextents++;
> > +
> > + error = xfs_next_set(bma->ip, whichfork, 1);
> > + if (error)
> > + goto done;
> >
> > if (bma->cur == NULL)
> > rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
> > @@ -1937,7 +1952,10 @@ xfs_bmap_add_extent_delay_real(
> > xfs_iext_next(ifp, &bma->icur);
> > xfs_iext_insert(bma->ip, &bma->icur, &RIGHT, state);
> > xfs_iext_insert(bma->ip, &bma->icur, &LEFT, state);
> > - ifp->if_nextents++;
> > +
> > + error = xfs_next_set(bma->ip, whichfork, 1);
> > + if (error)
> > + goto done;
> >
> > if (bma->cur == NULL)
> > rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
> > @@ -2141,7 +2159,11 @@ xfs_bmap_add_extent_unwritten_real(
> > xfs_iext_remove(ip, icur, state);
> > xfs_iext_prev(ifp, icur);
> > xfs_iext_update_extent(ip, state, icur, &LEFT);
> > - ifp->if_nextents -= 2;
> > +
> > + error = xfs_next_set(ip, whichfork, -2);
> > + if (error)
> > + goto done;
> > +
> > if (cur == NULL)
> > rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
> > else {
> > @@ -2193,7 +2215,11 @@ xfs_bmap_add_extent_unwritten_real(
> > xfs_iext_remove(ip, icur, state);
> > xfs_iext_prev(ifp, icur);
> > xfs_iext_update_extent(ip, state, icur, &LEFT);
> > - ifp->if_nextents--;
> > +
> > + error = xfs_next_set(ip, whichfork, -1);
> > + if (error)
> > + goto done;
> > +
> > if (cur == NULL)
> > rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
> > else {
> > @@ -2235,7 +2261,10 @@ xfs_bmap_add_extent_unwritten_real(
> > xfs_iext_remove(ip, icur, state);
> > xfs_iext_prev(ifp, icur);
> > xfs_iext_update_extent(ip, state, icur, &PREV);
> > - ifp->if_nextents--;
> > +
> > + error = xfs_next_set(ip, whichfork, -1);
> > + if (error)
> > + goto done;
> >
> > if (cur == NULL)
> > rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
> > @@ -2343,7 +2372,10 @@ xfs_bmap_add_extent_unwritten_real(
> >
> > xfs_iext_update_extent(ip, state, icur, &PREV);
> > xfs_iext_insert(ip, icur, new, state);
> > - ifp->if_nextents++;
> > +
> > + error = xfs_next_set(ip, whichfork, 1);
> > + if (error)
> > + goto done;
> >
> > if (cur == NULL)
> > rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
> > @@ -2419,7 +2451,10 @@ xfs_bmap_add_extent_unwritten_real(
> > xfs_iext_update_extent(ip, state, icur, &PREV);
> > xfs_iext_next(ifp, icur);
> > xfs_iext_insert(ip, icur, new, state);
> > - ifp->if_nextents++;
> > +
> > + error = xfs_next_set(ip, whichfork, 1);
> > + if (error)
> > + goto done;
> >
> > if (cur == NULL)
> > rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
> > @@ -2471,7 +2506,10 @@ xfs_bmap_add_extent_unwritten_real(
> > xfs_iext_next(ifp, icur);
> > xfs_iext_insert(ip, icur, &r[1], state);
> > xfs_iext_insert(ip, icur, &r[0], state);
> > - ifp->if_nextents += 2;
> > +
> > + error = xfs_next_set(ip, whichfork, 2);
> > + if (error)
> > + goto done;
> >
> > if (cur == NULL)
> > rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
> > @@ -2787,7 +2825,10 @@ xfs_bmap_add_extent_hole_real(
> > xfs_iext_remove(ip, icur, state);
> > xfs_iext_prev(ifp, icur);
> > xfs_iext_update_extent(ip, state, icur, &left);
> > - ifp->if_nextents--;
> > +
> > + error = xfs_next_set(ip, whichfork, -1);
> > + if (error)
> > + goto done;
> >
> > if (cur == NULL) {
> > rval = XFS_ILOG_CORE | xfs_ilog_fext(whichfork);
> > @@ -2886,7 +2927,10 @@ xfs_bmap_add_extent_hole_real(
> > * Insert a new entry.
> > */
> > xfs_iext_insert(ip, icur, new, state);
> > - ifp->if_nextents++;
> > +
> > + error = xfs_next_set(ip, whichfork, 1);
> > + if (error)
> > + goto done;
> >
> > if (cur == NULL) {
> > rval = XFS_ILOG_CORE | xfs_ilog_fext(whichfork);
> > @@ -5083,7 +5127,10 @@ xfs_bmap_del_extent_real(
> > */
> > xfs_iext_remove(ip, icur, state);
> > xfs_iext_prev(ifp, icur);
> > - ifp->if_nextents--;
> > +
> > + error = xfs_next_set(ip, whichfork, -1);
> > + if (error)
> > + goto done;
> >
> > flags |= XFS_ILOG_CORE;
> > if (!cur) {
> > @@ -5193,7 +5240,10 @@ xfs_bmap_del_extent_real(
> > } else
> > flags |= xfs_ilog_fext(whichfork);
> >
> > - ifp->if_nextents++;
> > + error = xfs_next_set(ip, whichfork, 1);
> > + if (error)
> > + goto done;
> > +
> > xfs_iext_next(ifp, icur);
> > xfs_iext_insert(ip, icur, &new, state);
> > break;
> > @@ -5660,7 +5710,10 @@ xfs_bmse_merge(
> > * Update the on-disk extent count, the btree if necessary and log the
> > * inode.
> > */
> > - ifp->if_nextents--;
> > + error = xfs_next_set(ip, whichfork, -1);
> > + if (error)
> > + goto done;
> > +
> > *logflags |= XFS_ILOG_CORE;
> > if (!cur) {
> > *logflags |= XFS_ILOG_DEXT;
> > @@ -6047,7 +6100,10 @@ xfs_bmap_split_extent(
> > /* Add new extent */
> > xfs_iext_next(ifp, &icur);
> > xfs_iext_insert(ip, &icur, &new, 0);
> > - ifp->if_nextents++;
> > +
> > + error = xfs_next_set(ip, whichfork, 1);
> > + if (error)
> > + goto del_cursor;
> >
> > if (cur) {
> > error = xfs_bmbt_lookup_eq(cur, &new, &i);
> > diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
> > index 28b366275ae0..3bf5a2c391bd 100644
> > --- a/fs/xfs/libxfs/xfs_inode_fork.c
> > +++ b/fs/xfs/libxfs/xfs_inode_fork.c
> > @@ -728,3 +728,32 @@ xfs_ifork_verify_local_attr(
> >
> > return 0;
> > }
> > +
> > +int
> > +xfs_next_set(
>
> "next"... please choose an abbreviation that doesn't collide with a
> common English word.
>
> > + struct xfs_inode *ip,
> > + int whichfork,
> > + int delta)
>
> Delta? I thought this was a setter function?
>
> > +{
> > + struct xfs_ifork *ifp;
> > + int64_t nr_exts;
> > + int64_t max_exts;
> > +
> > + ifp = XFS_IFORK_PTR(ip, whichfork);
> > +
> > + if (whichfork == XFS_DATA_FORK || whichfork == XFS_COW_FORK)
> > + max_exts = MAXEXTNUM;
> > + else if (whichfork == XFS_ATTR_FORK)
> > + max_exts = MAXAEXTNUM;
> > + else
> > + ASSERT(0);
> > +
> > + nr_exts = ifp->if_nextents + delta;
>
> Nope, it's a modify function all right. Then it should be named:
>
> xfs_nextents_mod(ip, whichfork, delta)

Ok. I will change this.

>
> > + if ((delta > 0 && nr_exts > max_exts)
> > + || (delta < 0 && nr_exts < 0))
>
> Line these up, please. e.g.,
>
> if ((delta > 0 && nr_exts > max_exts) ||
> (delta < 0 && nr_exts < 0))

Ok.

>
> --D
>
> > + return -EOVERFLOW;
> > +
> > + ifp->if_nextents = nr_exts;
> > +
> > + return 0;
> > +}
> > diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
> > index a4953e95c4f3..a84ae42ace79 100644
> > --- a/fs/xfs/libxfs/xfs_inode_fork.h
> > +++ b/fs/xfs/libxfs/xfs_inode_fork.h
> > @@ -173,4 +173,5 @@ extern void xfs_ifork_init_cow(struct xfs_inode *ip);
> > int xfs_ifork_verify_local_data(struct xfs_inode *ip);
> > int xfs_ifork_verify_local_attr(struct xfs_inode *ip);
> >
> > +int xfs_next_set(struct xfs_inode *ip, int whichfork, int delta);
> > #endif /* __XFS_INODE_FORK_H__ */
>

--
chandan