1 files changed, 201 insertions, 87 deletions

diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 07593a362cd0..4a84c5ea266d 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -82,11 +82,22 @@
  * mappings are a reservation against the free space in the filesystem;
  * adjacent mappings can also be combined into fewer larger mappings.
  *
+ * As an optimization, the CoW extent size hint (cowextsz) creates
+ * outsized aligned delalloc reservations in the hope of landing out of
+ * order nearby CoW writes in a single extent on disk, thereby reducing
+ * fragmentation and improving future performance.
+ *
+ * D: --RRRRRRSSSRRRRRRRR--- (data fork)
+ * C: ------DDDDDDD--------- (CoW fork)
+ *
  * When dirty pages are being written out (typically in writepage), the
- * delalloc reservations are converted into real mappings by allocating
- * blocks and replacing the delalloc mapping with real ones.  A delalloc
- * mapping can be replaced by several real ones if the free space is
- * fragmented.
+ * delalloc reservations are converted into unwritten mappings by
+ * allocating blocks and replacing the delalloc mapping with real ones.
+ * A delalloc mapping can be replaced by several unwritten ones if the
+ * free space is fragmented.
+ *
+ * D: --RRRRRRSSSRRRRRRRR---
+ * C: ------UUUUUUU---------
  *
  * We want to adapt the delalloc mechanism for copy-on-write, since the
  * write paths are similar.  The first two steps (creating the reservation
@@ -101,13 +112,29 @@
  * Block-aligned directio writes will use the same mechanism as buffered
  * writes.
  *
+ * Just prior to submitting the actual disk write requests, we convert
+ * the extents representing the range of the file actually being written
+ * (as opposed to extra pieces created for the cowextsize hint) to real
+ * extents.  This will become important in the next step:
+ *
+ * D: --RRRRRRSSSRRRRRRRR---
+ * C: ------UUrrUUU---------
+ *
  * CoW remapping must be done after the data block write completes,
  * because we don't want to destroy the old data fork map until we're sure
  * the new block has been written.  Since the new mappings are kept in a
  * separate fork, we can simply iterate these mappings to find the ones
  * that cover the file blocks that we just CoW'd.  For each extent, simply
  * unmap the corresponding range in the data fork, map the new range into
- * the data fork, and remove the extent from the CoW fork.
+ * the data fork, and remove the extent from the CoW fork.  Because of
+ * the presence of the cowextsize hint, however, we must be careful
+ * only to remap the blocks that we've actually written out --  we must
+ * never remap delalloc reservations nor CoW staging blocks that have
+ * yet to be written.  This corresponds exactly to the real extents in
+ * the CoW fork:
+ *
+ * D: --RRRRRRrrSRRRRRRRR---
+ * C: ------UU--UUU---------
  *
  * Since the remapping operation can be applied to an arbitrary file
  * range, we record the need for the remap step as a flag in the ioend
@@ -296,103 +323,165 @@ xfs_reflink_reserve_cow(
 	return 0;
 }
 
-/* Allocate all CoW reservations covering a range of blocks in a file. */
-static int
-__xfs_reflink_allocate_cow(
-	struct xfs_inode	*ip,
-	xfs_fileoff_t		*offset_fsb,
-	xfs_fileoff_t		end_fsb)
+/* Convert part of an unwritten CoW extent to a real one. */
+STATIC int
+xfs_reflink_convert_cow_extent(
+	struct xfs_inode		*ip,
+	struct xfs_bmbt_irec		*imap,
+	xfs_fileoff_t			offset_fsb,
+	xfs_filblks_t			count_fsb,
+	struct xfs_defer_ops		*dfops)
 {
-	struct xfs_mount	*mp = ip->i_mount;
-	struct xfs_bmbt_irec	imap;
-	struct xfs_defer_ops	dfops;
-	struct xfs_trans	*tp;
-	xfs_fsblock_t		first_block;
-	int			nimaps = 1, error;
-	bool			shared;
-
-	xfs_defer_init(&dfops, &first_block);
+	xfs_fsblock_t			first_block;
+	int				nimaps = 1;
 
-	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0,
-			XFS_TRANS_RESERVE, &tp);
-	if (error)
-		return error;
+	if (imap->br_state == XFS_EXT_NORM)
+		return 0;
 
-	xfs_ilock(ip, XFS_ILOCK_EXCL);
+	xfs_trim_extent(imap, offset_fsb, count_fsb);
+	trace_xfs_reflink_convert_cow(ip, imap);
+	if (imap->br_blockcount == 0)
+		return 0;
+	return xfs_bmapi_write(NULL, ip, imap->br_startoff, imap->br_blockcount,
+			XFS_BMAPI_COWFORK | XFS_BMAPI_CONVERT, &first_block,
+			0, imap, &nimaps, dfops);
+}
 
-	/* Read extent from the source file. */
-	nimaps = 1;
-	error = xfs_bmapi_read(ip, *offset_fsb, end_fsb - *offset_fsb,
-			&imap, &nimaps, 0);
-	if (error)
-		goto out_unlock;
-	ASSERT(nimaps == 1);
+/* Convert all of the unwritten CoW extents in a file's range to real ones. */
+int
+xfs_reflink_convert_cow(
+	struct xfs_inode	*ip,
+	xfs_off_t		offset,
+	xfs_off_t		count)
+{
+	struct xfs_bmbt_irec	got;
+	struct xfs_defer_ops	dfops;
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
+	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset);
+	xfs_fileoff_t		end_fsb = XFS_B_TO_FSB(mp, offset + count);
+	xfs_extnum_t		idx;
+	bool			found;
+	int			error = 0;
 
-	error = xfs_reflink_reserve_cow(ip, &imap, &shared);
-	if (error)
-		goto out_trans_cancel;
+	xfs_ilock(ip, XFS_ILOCK_EXCL);
 
-	if (!shared) {
-		*offset_fsb = imap.br_startoff + imap.br_blockcount;
-		goto out_trans_cancel;
+	/* Convert all the extents to real from unwritten. */
+	for (found = xfs_iext_lookup_extent(ip, ifp, offset_fsb, &idx, &got);
+	     found && got.br_startoff < end_fsb;
+	     found = xfs_iext_get_extent(ifp, ++idx, &got)) {
+		error = xfs_reflink_convert_cow_extent(ip, &got, offset_fsb,
+				end_fsb - offset_fsb, &dfops);
+		if (error)
+			break;
 	}
 
-	xfs_trans_ijoin(tp, ip, 0);
-	error = xfs_bmapi_write(tp, ip, imap.br_startoff, imap.br_blockcount,
-			XFS_BMAPI_COWFORK, &first_block,
-			XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK),
-			&imap, &nimaps, &dfops);
-	if (error)
-		goto out_trans_cancel;
-
-	error = xfs_defer_finish(&tp, &dfops, NULL);
-	if (error)
-		goto out_trans_cancel;
-
-	error = xfs_trans_commit(tp);
-
-	*offset_fsb = imap.br_startoff + imap.br_blockcount;
-out_unlock:
+	/* Finish up. */
 	xfs_iunlock(ip, XFS_ILOCK_EXCL);
 	return error;
-out_trans_cancel:
-	xfs_defer_cancel(&dfops);
-	xfs_trans_cancel(tp);
-	goto out_unlock;
 }
 
-/* Allocate all CoW reservations covering a part of a file. */
+/* Allocate all CoW reservations covering a range of blocks in a file. */
 int
-xfs_reflink_allocate_cow_range(
+xfs_reflink_allocate_cow(
 	struct xfs_inode	*ip,
-	xfs_off_t		offset,
-	xfs_off_t		count)
+	struct xfs_bmbt_irec	*imap,
+	bool			*shared,
+	uint			*lockmode)
 {
 	struct xfs_mount	*mp = ip->i_mount;
-	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset);
-	xfs_fileoff_t		end_fsb = XFS_B_TO_FSB(mp, offset + count);
-	int			error;
+	xfs_fileoff_t		offset_fsb = imap->br_startoff;
+	xfs_filblks_t		count_fsb = imap->br_blockcount;
+	struct xfs_bmbt_irec	got;
+	struct xfs_defer_ops	dfops;
+	struct xfs_trans	*tp = NULL;
+	xfs_fsblock_t		first_block;
+	int			nimaps, error = 0;
+	bool			trimmed;
+	xfs_filblks_t		resaligned;
+	xfs_extlen_t		resblks = 0;
+	xfs_extnum_t		idx;
 
+retry:
 	ASSERT(xfs_is_reflink_inode(ip));
-
-	trace_xfs_reflink_allocate_cow_range(ip, offset, count);
+	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL | XFS_ILOCK_SHARED));
 
 	/*
-	 * Make sure that the dquots are there.
+	 * Even if the extent is not shared we might have a preallocation for
+	 * it in the COW fork.  If so use it.
 	 */
-	error = xfs_qm_dqattach(ip, 0);
-	if (error)
-		return error;
+	if (xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &idx, &got) &&
+	    got.br_startoff <= offset_fsb) {
+		*shared = true;
 
-	while (offset_fsb < end_fsb) {
-		error = __xfs_reflink_allocate_cow(ip, &offset_fsb, end_fsb);
-		if (error) {
-			trace_xfs_reflink_allocate_cow_range_error(ip, error,
-					_RET_IP_);
-			break;
+		/* If we have a real allocation in the COW fork we're done. */
+		if (!isnullstartblock(got.br_startblock)) {
+			xfs_trim_extent(&got, offset_fsb, count_fsb);
+			*imap = got;
+			goto convert;
 		}
+
+		xfs_trim_extent(imap, got.br_startoff, got.br_blockcount);
+	} else {
+		error = xfs_reflink_trim_around_shared(ip, imap, shared, &trimmed);
+		if (error || !*shared)
+			goto out;
+	}
+
+	if (!tp) {
+		resaligned = xfs_aligned_fsb_count(imap->br_startoff,
+			imap->br_blockcount, xfs_get_cowextsz_hint(ip));
+		resblks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
+
+		xfs_iunlock(ip, *lockmode);
+		error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0, 0, &tp);
+		*lockmode = XFS_ILOCK_EXCL;
+		xfs_ilock(ip, *lockmode);
+
+		if (error)
+			return error;
+
+		error = xfs_qm_dqattach_locked(ip, 0);
+		if (error)
+			goto out;
+		goto retry;
 	}
 
+	error = xfs_trans_reserve_quota_nblks(tp, ip, resblks, 0,
+			XFS_QMOPT_RES_REGBLKS);
+	if (error)
+		goto out;
+
+	xfs_trans_ijoin(tp, ip, 0);
+
+	xfs_defer_init(&dfops, &first_block);
+	nimaps = 1;
+
+	/* Allocate the entire reservation as unwritten blocks. */
+	error = xfs_bmapi_write(tp, ip, imap->br_startoff, imap->br_blockcount,
+			XFS_BMAPI_COWFORK | XFS_BMAPI_PREALLOC, &first_block,
+			resblks, imap, &nimaps, &dfops);
+	if (error)
+		goto out_bmap_cancel;
+
+	/* Finish up. */
+	error = xfs_defer_finish(&tp, &dfops, NULL);
+	if (error)
+		goto out_bmap_cancel;
+
+	error = xfs_trans_commit(tp);
+	if (error)
+		return error;
+convert:
+	return xfs_reflink_convert_cow_extent(ip, imap, offset_fsb, count_fsb,
+			&dfops);
+out_bmap_cancel:
+	xfs_defer_cancel(&dfops);
+	xfs_trans_unreserve_quota_nblks(tp, ip, (long)resblks, 0,
+			XFS_QMOPT_RES_REGBLKS);
+out:
+	if (tp)
+		xfs_trans_cancel(tp);
 	return error;
 }
 
@@ -459,14 +548,18 @@ xfs_reflink_trim_irec_to_next_cow(
 }
 
 /*
- * Cancel all pending CoW reservations for some block range of an inode.
+ * Cancel CoW reservations for some block range of an inode.
+ *
+ * If cancel_real is true this function cancels all COW fork extents for the
+ * inode; if cancel_real is false, real extents are not cleared.
  */
 int
 xfs_reflink_cancel_cow_blocks(
 	struct xfs_inode		*ip,
 	struct xfs_trans		**tpp,
 	xfs_fileoff_t			offset_fsb,
-	xfs_fileoff_t			end_fsb)
+	xfs_fileoff_t			end_fsb,
+	bool				cancel_real)
 {
 	struct xfs_ifork		*ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
 	struct xfs_bmbt_irec		got, del;
@@ -490,7 +583,7 @@ xfs_reflink_cancel_cow_blocks(
 					&idx, &got, &del);
 			if (error)
 				break;
-		} else {
+		} else if (del.br_state == XFS_EXT_UNWRITTEN || cancel_real) {
 			xfs_trans_ijoin(*tpp, ip, 0);
 			xfs_defer_init(&dfops, &firstfsb);
 
@@ -532,13 +625,17 @@ xfs_reflink_cancel_cow_blocks(
 }
 
 /*
- * Cancel all pending CoW reservations for some byte range of an inode.
+ * Cancel CoW reservations for some byte range of an inode.
+ *
+ * If cancel_real is true this function cancels all COW fork extents for the
+ * inode; if cancel_real is false, real extents are not cleared.
  */
 int
 xfs_reflink_cancel_cow_range(
 	struct xfs_inode	*ip,
 	xfs_off_t		offset,
-	xfs_off_t		count)
+	xfs_off_t		count,
+	bool			cancel_real)
 {
 	struct xfs_trans	*tp;
 	xfs_fileoff_t		offset_fsb;
@@ -564,7 +661,8 @@ xfs_reflink_cancel_cow_range(
 	xfs_trans_ijoin(tp, ip, 0);
 
 	/* Scrape out the old CoW reservations */
-	error = xfs_reflink_cancel_cow_blocks(ip, &tp, offset_fsb, end_fsb);
+	error = xfs_reflink_cancel_cow_blocks(ip, &tp, offset_fsb, end_fsb,
+			cancel_real);
 	if (error)
 		goto out_cancel;
 
@@ -641,6 +739,16 @@ xfs_reflink_end_cow(
 
 		ASSERT(!isnullstartblock(got.br_startblock));
 
+		/*
+		 * Don't remap unwritten extents; these are
+		 * speculatively preallocated CoW extents that have been
+		 * allocated but have not yet been involved in a write.
+		 */
+		if (got.br_state == XFS_EXT_UNWRITTEN) {
+			idx--;
+			goto next_extent;
+		}
+
 		/* Unmap the old blocks in the data fork. */
 		xfs_defer_init(&dfops, &firstfsb);
 		rlen = del.br_blockcount;
@@ -855,13 +963,14 @@ STATIC int
 xfs_reflink_update_dest(
 	struct xfs_inode	*dest,
 	xfs_off_t		newlen,
-	xfs_extlen_t		cowextsize)
+	xfs_extlen_t		cowextsize,
+	bool			is_dedupe)
 {
 	struct xfs_mount	*mp = dest->i_mount;
 	struct xfs_trans	*tp;
 	int			error;
 
-	if (newlen <= i_size_read(VFS_I(dest)) && cowextsize == 0)
+	if (is_dedupe && newlen <= i_size_read(VFS_I(dest)) && cowextsize == 0)
 		return 0;
 
 	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
@@ -882,6 +991,10 @@ xfs_reflink_update_dest(
 		dest->i_d.di_flags2 |= XFS_DIFLAG2_COWEXTSIZE;
 	}
 
+	if (!is_dedupe) {
+		xfs_trans_ichgtime(tp, dest,
+				   XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
+	}
 	xfs_trans_log_inode(tp, dest, XFS_ILOG_CORE);
 
 	error = xfs_trans_commit(tp);
@@ -1195,7 +1308,8 @@ xfs_reflink_remap_range(
 	    !(dest->i_d.di_flags2 & XFS_DIFLAG2_COWEXTSIZE))
 		cowextsize = src->i_d.di_cowextsize;
 
-	ret = xfs_reflink_update_dest(dest, pos_out + len, cowextsize);
+	ret = xfs_reflink_update_dest(dest, pos_out + len, cowextsize,
+			is_dedupe);
 
 out_unlock:
 	xfs_iunlock(src, XFS_MMAPLOCK_EXCL);
@@ -1345,7 +1459,7 @@ next:
 	 * We didn't find any shared blocks so turn off the reflink flag.
 	 * First, get rid of any leftover CoW mappings.
 	 */
-	error = xfs_reflink_cancel_cow_blocks(ip, tpp, 0, NULLFILEOFF);
+	error = xfs_reflink_cancel_cow_blocks(ip, tpp, 0, NULLFILEOFF, true);
 	if (error)
 		return error;