Re: [PATCH 038/119] xfs: convert unwritten status of reverse mappings

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On Thu, Jun 16, 2016 at 06:21:55PM -0700, Darrick J. Wong wrote:
> Provide a function to convert an unwritten extent to a real one and
> vice versa.
> 
> v2: Move unwritten bit to rm_offset.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> ---
>  fs/xfs/libxfs/xfs_rmap.c |  442 ++++++++++++++++++++++++++++++++++++++++++++++
>  fs/xfs/xfs_trace.h       |    6 +
>  2 files changed, 448 insertions(+)
> 
> 
> diff --git a/fs/xfs/libxfs/xfs_rmap.c b/fs/xfs/libxfs/xfs_rmap.c
> index 1043c63..53ba14e 100644
> --- a/fs/xfs/libxfs/xfs_rmap.c
> +++ b/fs/xfs/libxfs/xfs_rmap.c
> @@ -610,6 +610,448 @@ out_error:
>  	return error;
>  }
>  
> +#define RMAP_LEFT_CONTIG	(1 << 0)
> +#define RMAP_RIGHT_CONTIG	(1 << 1)
> +#define RMAP_LEFT_FILLING	(1 << 2)
> +#define RMAP_RIGHT_FILLING	(1 << 3)
> +#define RMAP_LEFT_VALID		(1 << 6)
> +#define RMAP_RIGHT_VALID	(1 << 7)
> +
> +#define LEFT		r[0]
> +#define RIGHT		r[1]
> +#define PREV		r[2]
> +#define NEW		r[3]
> +
> +/*
> + * Convert an unwritten extent to a real extent or vice versa.
> + * Does not handle overlapping extents.
> + */
> +STATIC int
> +__xfs_rmap_convert(
> +	struct xfs_btree_cur	*cur,
> +	xfs_agblock_t		bno,
> +	xfs_extlen_t		len,
> +	bool			unwritten,
> +	struct xfs_owner_info	*oinfo)
> +{
> +	struct xfs_mount	*mp = cur->bc_mp;
> +	struct xfs_rmap_irec	r[4];	/* neighbor extent entries */
> +					/* left is 0, right is 1, prev is 2 */
> +					/* new is 3 */
> +	uint64_t		owner;
> +	uint64_t		offset;
> +	uint64_t		new_endoff;
> +	unsigned int		oldext;
> +	unsigned int		newext;
> +	unsigned int		flags = 0;
> +	int			i;
> +	int			state = 0;
> +	int			error;
> +
> +	xfs_owner_info_unpack(oinfo, &owner, &offset, &flags);
> +	ASSERT(!(XFS_RMAP_NON_INODE_OWNER(owner) ||
> +			(flags & (XFS_RMAP_ATTR_FORK | XFS_RMAP_BMBT_BLOCK))));
> +	oldext = unwritten ? XFS_RMAP_UNWRITTEN : 0;
> +	new_endoff = offset + len;
> +	trace_xfs_rmap_convert(mp, cur->bc_private.a.agno, bno, len,
> +			unwritten, oinfo);
> +
> +	/*
> +	 * For the initial lookup, look for and exact match or the left-adjacent
> +	 * record for our insertion point. This will also give us the record for
> +	 * start block contiguity tests.
> +	 */
> +	error = xfs_rmap_lookup_le(cur, bno, len, owner, offset, oldext, &i);
> +	if (error)
> +		goto done;
> +	XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +
> +	error = xfs_rmap_get_rec(cur, &PREV, &i);
> +	if (error)
> +		goto done;
> +	XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +	trace_xfs_rmap_lookup_le_range_result(cur->bc_mp,
> +			cur->bc_private.a.agno, PREV.rm_startblock,
> +			PREV.rm_blockcount, PREV.rm_owner,
> +			PREV.rm_offset, PREV.rm_flags);
> +
> +	ASSERT(PREV.rm_offset <= offset);
> +	ASSERT(PREV.rm_offset + PREV.rm_blockcount >= new_endoff);
> +	ASSERT((PREV.rm_flags & XFS_RMAP_UNWRITTEN) == oldext);
> +	newext = ~oldext & XFS_RMAP_UNWRITTEN;
> +
> +	/*
> +	 * Set flags determining what part of the previous oldext allocation
> +	 * extent is being replaced by a newext allocation.
> +	 */
> +	if (PREV.rm_offset == offset)
> +		state |= RMAP_LEFT_FILLING;
> +	if (PREV.rm_offset + PREV.rm_blockcount == new_endoff)
> +		state |= RMAP_RIGHT_FILLING;
> +
> +	/*
> +	 * Decrement the cursor to see if we have a left-adjacent record to our
> +	 * insertion point. This will give us the record for end block
> +	 * contiguity tests.
> +	 */
> +	error = xfs_btree_decrement(cur, 0, &i);
> +	if (error)
> +		goto done;
> +	if (i) {
> +		state |= RMAP_LEFT_VALID;
> +		error = xfs_rmap_get_rec(cur, &LEFT, &i);
> +		if (error)
> +			goto done;
> +		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +		XFS_WANT_CORRUPTED_GOTO(mp,
> +				LEFT.rm_startblock + LEFT.rm_blockcount <= bno,
> +				done);
> +		trace_xfs_rmap_find_left_neighbor_result(cur->bc_mp,
> +				cur->bc_private.a.agno, LEFT.rm_startblock,
> +				LEFT.rm_blockcount, LEFT.rm_owner,
> +				LEFT.rm_offset, LEFT.rm_flags);
> +		if (LEFT.rm_startblock + LEFT.rm_blockcount == bno &&
> +		    LEFT.rm_offset + LEFT.rm_blockcount == offset &&
> +		    xfs_rmap_is_mergeable(&LEFT, owner, offset, len, newext))
> +			state |= RMAP_LEFT_CONTIG;
> +	}
> +
> +	/*
> +	 * Increment the cursor to see if we have a right-adjacent record to our
> +	 * insertion point. This will give us the record for end block
> +	 * contiguity tests.
> +	 */
> +	error = xfs_btree_increment(cur, 0, &i);
> +	if (error)
> +		goto done;
> +	XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +	error = xfs_btree_increment(cur, 0, &i);
> +	if (error)
> +		goto done;
> +	if (i) {
> +		state |= RMAP_RIGHT_VALID;
> +		error = xfs_rmap_get_rec(cur, &RIGHT, &i);
> +		if (error)
> +			goto done;
> +		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +		XFS_WANT_CORRUPTED_GOTO(mp, bno + len <= RIGHT.rm_startblock,
> +					done);
> +		trace_xfs_rmap_convert_gtrec(cur->bc_mp,
> +				cur->bc_private.a.agno, RIGHT.rm_startblock,
> +				RIGHT.rm_blockcount, RIGHT.rm_owner,
> +				RIGHT.rm_offset, RIGHT.rm_flags);
> +		if (bno + len == RIGHT.rm_startblock &&
> +		    offset + len == RIGHT.rm_offset &&
> +		    xfs_rmap_is_mergeable(&RIGHT, owner, offset, len, newext))
> +			state |= RMAP_RIGHT_CONTIG;
> +	}
> +
> +	/* check that left + prev + right is not too long */
> +	if ((state & (RMAP_LEFT_FILLING | RMAP_LEFT_CONTIG |
> +			 RMAP_RIGHT_FILLING | RMAP_RIGHT_CONTIG)) ==
> +	    (RMAP_LEFT_FILLING | RMAP_LEFT_CONTIG |
> +	     RMAP_RIGHT_FILLING | RMAP_RIGHT_CONTIG) &&
> +	    (unsigned long)LEFT.rm_blockcount + len +
> +	     RIGHT.rm_blockcount > XFS_RMAP_LEN_MAX)
> +		state &= ~RMAP_RIGHT_CONTIG;
> +
> +	trace_xfs_rmap_convert_state(mp, cur->bc_private.a.agno, state,
> +			_RET_IP_);
> +
> +	/* reset the cursor back to PREV */
> +	error = xfs_rmap_lookup_le(cur, bno, len, owner, offset, oldext, &i);
> +	if (error)
> +		goto done;
> +	XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +
> +	/*
> +	 * Switch out based on the FILLING and CONTIG state bits.
> +	 */
> +	switch (state & (RMAP_LEFT_FILLING | RMAP_LEFT_CONTIG |
> +			 RMAP_RIGHT_FILLING | RMAP_RIGHT_CONTIG)) {
> +	case RMAP_LEFT_FILLING | RMAP_LEFT_CONTIG |
> +	     RMAP_RIGHT_FILLING | RMAP_RIGHT_CONTIG:
> +		/*
> +		 * Setting all of a previous oldext extent to newext.
> +		 * The left and right neighbors are both contiguous with new.
> +		 */
> +		error = xfs_btree_increment(cur, 0, &i);
> +		if (error)
> +			goto done;
> +		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +		trace_xfs_rmapbt_delete(mp, cur->bc_private.a.agno,
> +				RIGHT.rm_startblock, RIGHT.rm_blockcount,
> +				RIGHT.rm_owner, RIGHT.rm_offset,
> +				RIGHT.rm_flags);
> +		error = xfs_btree_delete(cur, &i);
> +		if (error)
> +			goto done;
> +		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +		error = xfs_btree_decrement(cur, 0, &i);
> +		if (error)
> +			goto done;
> +		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +		trace_xfs_rmapbt_delete(mp, cur->bc_private.a.agno,
> +				PREV.rm_startblock, PREV.rm_blockcount,
> +				PREV.rm_owner, PREV.rm_offset,
> +				PREV.rm_flags);
> +		error = xfs_btree_delete(cur, &i);
> +		if (error)
> +			goto done;
> +		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +		error = xfs_btree_decrement(cur, 0, &i);
> +		if (error)
> +			goto done;
> +		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +		NEW = LEFT;
> +		NEW.rm_blockcount += PREV.rm_blockcount + RIGHT.rm_blockcount;
> +		error = xfs_rmap_update(cur, &NEW);
> +		if (error)
> +			goto done;
> +		break;
> +
> +	case RMAP_LEFT_FILLING | RMAP_RIGHT_FILLING | RMAP_LEFT_CONTIG:
> +		/*
> +		 * Setting all of a previous oldext extent to newext.
> +		 * The left neighbor is contiguous, the right is not.
> +		 */
> +		trace_xfs_rmapbt_delete(mp, cur->bc_private.a.agno,
> +				PREV.rm_startblock, PREV.rm_blockcount,
> +				PREV.rm_owner, PREV.rm_offset,
> +				PREV.rm_flags);
> +		error = xfs_btree_delete(cur, &i);
> +		if (error)
> +			goto done;
> +		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +		error = xfs_btree_decrement(cur, 0, &i);
> +		if (error)
> +			goto done;
> +		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +		NEW = LEFT;
> +		NEW.rm_blockcount += PREV.rm_blockcount;
> +		error = xfs_rmap_update(cur, &NEW);
> +		if (error)
> +			goto done;
> +		break;
> +
> +	case RMAP_LEFT_FILLING | RMAP_RIGHT_FILLING | RMAP_RIGHT_CONTIG:
> +		/*
> +		 * Setting all of a previous oldext extent to newext.
> +		 * The right neighbor is contiguous, the left is not.
> +		 */
> +		error = xfs_btree_increment(cur, 0, &i);
> +		if (error)
> +			goto done;
> +		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +		trace_xfs_rmapbt_delete(mp, cur->bc_private.a.agno,
> +				RIGHT.rm_startblock, RIGHT.rm_blockcount,
> +				RIGHT.rm_owner, RIGHT.rm_offset,
> +				RIGHT.rm_flags);
> +		error = xfs_btree_delete(cur, &i);
> +		if (error)
> +			goto done;
> +		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +		error = xfs_btree_decrement(cur, 0, &i);
> +		if (error)
> +			goto done;
> +		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +		NEW.rm_startblock = bno;
> +		NEW.rm_owner = owner;
> +		NEW.rm_offset = offset;
> +		NEW.rm_blockcount = len + RIGHT.rm_blockcount;
> +		NEW.rm_flags = newext;
> +		error = xfs_rmap_update(cur, &NEW);
> +		if (error)
> +			goto done;
> +		break;
> +
> +	case RMAP_LEFT_FILLING | RMAP_RIGHT_FILLING:
> +		/*
> +		 * Setting all of a previous oldext extent to newext.
> +		 * Neither the left nor right neighbors are contiguous with
> +		 * the new one.
> +		 */
> +		NEW = PREV;
> +		NEW.rm_flags = newext;
> +		error = xfs_rmap_update(cur, &NEW);
> +		if (error)
> +			goto done;
> +		break;
> +
> +	case RMAP_LEFT_FILLING | RMAP_LEFT_CONTIG:
> +		/*
> +		 * Setting the first part of a previous oldext extent to newext.
> +		 * The left neighbor is contiguous.
> +		 */
> +		NEW = PREV;
> +		NEW.rm_offset += len;
> +		NEW.rm_startblock += len;
> +		NEW.rm_blockcount -= len;
> +		error = xfs_rmap_update(cur, &NEW);
> +		if (error)
> +			goto done;
> +		error = xfs_btree_decrement(cur, 0, &i);
> +		if (error)
> +			goto done;
> +		NEW = LEFT;
> +		NEW.rm_blockcount += len;
> +		error = xfs_rmap_update(cur, &NEW);
> +		if (error)
> +			goto done;
> +		break;
> +
> +	case RMAP_LEFT_FILLING:
> +		/*
> +		 * Setting the first part of a previous oldext extent to newext.
> +		 * The left neighbor is not contiguous.
> +		 */
> +		NEW = PREV;
> +		NEW.rm_startblock += len;
> +		NEW.rm_offset += len;
> +		NEW.rm_blockcount -= len;
> +		error = xfs_rmap_update(cur, &NEW);
> +		if (error)
> +			goto done;
> +		NEW.rm_startblock = bno;
> +		NEW.rm_owner = owner;
> +		NEW.rm_offset = offset;
> +		NEW.rm_blockcount = len;
> +		NEW.rm_flags = newext;
> +		cur->bc_rec.r = NEW;
> +		trace_xfs_rmapbt_insert(mp, cur->bc_private.a.agno, bno,
> +				len, owner, offset, newext);
> +		error = xfs_btree_insert(cur, &i);
> +		if (error)
> +			goto done;
> +		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +		break;
> +
> +	case RMAP_RIGHT_FILLING | RMAP_RIGHT_CONTIG:
> +		/*
> +		 * Setting the last part of a previous oldext extent to newext.
> +		 * The right neighbor is contiguous with the new allocation.
> +		 */
> +		NEW = PREV;
> +		NEW.rm_blockcount -= len;
> +		error = xfs_rmap_update(cur, &NEW);
> +		if (error)
> +			goto done;
> +		error = xfs_btree_increment(cur, 0, &i);
> +		if (error)
> +			goto done;
> +		NEW = RIGHT;
> +		NEW.rm_offset = offset;
> +		NEW.rm_startblock = bno;
> +		NEW.rm_blockcount += len;
> +		error = xfs_rmap_update(cur, &NEW);
> +		if (error)
> +			goto done;
> +		break;
> +
> +	case RMAP_RIGHT_FILLING:
> +		/*
> +		 * Setting the last part of a previous oldext extent to newext.
> +		 * The right neighbor is not contiguous.
> +		 */
> +		NEW = PREV;
> +		NEW.rm_blockcount -= len;
> +		error = xfs_rmap_update(cur, &NEW);
> +		if (error)
> +			goto done;
> +		error = xfs_rmap_lookup_eq(cur, bno, len, owner, offset,
> +				oldext, &i);
> +		if (error)
> +			goto done;
> +		XFS_WANT_CORRUPTED_GOTO(mp, i == 0, done);
> +		NEW.rm_startblock = bno;
> +		NEW.rm_owner = owner;
> +		NEW.rm_offset = offset;
> +		NEW.rm_blockcount = len;
> +		NEW.rm_flags = newext;
> +		cur->bc_rec.r = NEW;
> +		trace_xfs_rmapbt_insert(mp, cur->bc_private.a.agno, bno,
> +				len, owner, offset, newext);
> +		error = xfs_btree_insert(cur, &i);
> +		if (error)
> +			goto done;
> +		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +		break;
> +
> +	case 0:
> +		/*
> +		 * Setting the middle part of a previous oldext extent to
> +		 * newext.  Contiguity is impossible here.
> +		 * One extent becomes three extents.
> +		 */
> +		/* new right extent - oldext */
> +		NEW.rm_startblock = bno + len;
> +		NEW.rm_owner = owner;
> +		NEW.rm_offset = new_endoff;
> +		NEW.rm_blockcount = PREV.rm_offset + PREV.rm_blockcount -
> +				new_endoff;
> +		NEW.rm_flags = PREV.rm_flags;
> +		error = xfs_rmap_update(cur, &NEW);
> +		if (error)
> +			goto done;
> +		/* new left extent - oldext */
> +		NEW = PREV;
> +		NEW.rm_blockcount = offset - PREV.rm_offset;
> +		cur->bc_rec.r = NEW;
> +		trace_xfs_rmapbt_insert(mp, cur->bc_private.a.agno,
> +				NEW.rm_startblock, NEW.rm_blockcount,
> +				NEW.rm_owner, NEW.rm_offset,
> +				NEW.rm_flags);
> +		error = xfs_btree_insert(cur, &i);
> +		if (error)
> +			goto done;
> +		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +		/*
> +		 * Reset the cursor to the position of the new extent
> +		 * we are about to insert as we can't trust it after
> +		 * the previous insert.
> +		 */
> +		error = xfs_rmap_lookup_eq(cur, bno, len, owner, offset,
> +				oldext, &i);
> +		if (error)
> +			goto done;
> +		XFS_WANT_CORRUPTED_GOTO(mp, i == 0, done);
> +		/* new middle extent - newext */
> +		cur->bc_rec.b.br_state = newext;

Wrong, should be:

		cur->bc_rec.r.rm_flags &= ~XFS_RMAP_UNWRITTEN;
		cur->bc_rec.r.rm_flags |= newext;

We're modifying the rmapbt here, not the bmbt, so it makes no sense to touch
the bmbt_irec in the cursor.  Modify the rmap_irec instead.  Incidentally
this just happens not to fail because the fields line up....

--D

> +		trace_xfs_rmapbt_insert(mp, cur->bc_private.a.agno, bno, len,
> +				owner, offset, newext);
> +		error = xfs_btree_insert(cur, &i);
> +		if (error)
> +			goto done;
> +		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +		break;
> +
> +	case RMAP_LEFT_FILLING | RMAP_LEFT_CONTIG | RMAP_RIGHT_CONTIG:
> +	case RMAP_RIGHT_FILLING | RMAP_LEFT_CONTIG | RMAP_RIGHT_CONTIG:
> +	case RMAP_LEFT_FILLING | RMAP_RIGHT_CONTIG:
> +	case RMAP_RIGHT_FILLING | RMAP_LEFT_CONTIG:
> +	case RMAP_LEFT_CONTIG | RMAP_RIGHT_CONTIG:
> +	case RMAP_LEFT_CONTIG:
> +	case RMAP_RIGHT_CONTIG:
> +		/*
> +		 * These cases are all impossible.
> +		 */
> +		ASSERT(0);
> +	}
> +
> +	trace_xfs_rmap_convert_done(mp, cur->bc_private.a.agno, bno, len,
> +			unwritten, oinfo);
> +done:
> +	if (error)
> +		trace_xfs_rmap_convert_error(cur->bc_mp,
> +				cur->bc_private.a.agno, error, _RET_IP_);
> +	return error;
> +}
> +
> +#undef	NEW
> +#undef	LEFT
> +#undef	RIGHT
> +#undef	PREV
> +
>  struct xfs_rmapbt_query_range_info {
>  	xfs_rmapbt_query_range_fn	fn;
>  	void				*priv;
> diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
> index 3ebceb0..6466adc 100644
> --- a/fs/xfs/xfs_trace.h
> +++ b/fs/xfs/xfs_trace.h
> @@ -2497,6 +2497,10 @@ DEFINE_RMAP_EVENT(xfs_rmap_free_extent_error);
>  DEFINE_RMAP_EVENT(xfs_rmap_alloc_extent);
>  DEFINE_RMAP_EVENT(xfs_rmap_alloc_extent_done);
>  DEFINE_RMAP_EVENT(xfs_rmap_alloc_extent_error);
> +DEFINE_RMAP_EVENT(xfs_rmap_convert);
> +DEFINE_RMAP_EVENT(xfs_rmap_convert_done);
> +DEFINE_AG_ERROR_EVENT(xfs_rmap_convert_error);
> +DEFINE_AG_ERROR_EVENT(xfs_rmap_convert_state);
>  
>  DECLARE_EVENT_CLASS(xfs_rmapbt_class,
>  	TP_PROTO(struct xfs_mount *mp, xfs_agnumber_t agno,
> @@ -2551,6 +2555,8 @@ DEFINE_AG_ERROR_EVENT(xfs_rmapbt_delete_error);
>  DEFINE_AG_ERROR_EVENT(xfs_rmapbt_update_error);
>  DEFINE_RMAPBT_EVENT(xfs_rmap_lookup_le_range_result);
>  DEFINE_RMAPBT_EVENT(xfs_rmap_map_gtrec);
> +DEFINE_RMAPBT_EVENT(xfs_rmap_convert_gtrec);
> +DEFINE_RMAPBT_EVENT(xfs_rmap_find_left_neighbor_result);
>  
>  #endif /* _TRACE_XFS_H */
>  
> 
> _______________________________________________
> xfs mailing list
> xfs@xxxxxxxxxxx
> http://oss.sgi.com/mailman/listinfo/xfs

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