xfs: split xfs_free_file_space in manageable pieces

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

fs/xfs/xfs_bmap_util.c

@@ -1184,69 +1184,72 @@ xfs_zero_remaining_bytes(
 	return error;
 }
 
-int
-xfs_free_file_space(
+static int
+xfs_unmap_extent(
 	struct xfs_inode	*ip,
-	xfs_off_t		offset,
-	xfs_off_t		len)
+	xfs_fileoff_t		startoffset_fsb,
+	xfs_filblks_t		len_fsb,
+	int			*done)
 {
-	int			done;
-	xfs_fileoff_t		endoffset_fsb;
-	int			error;
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_trans	*tp;
+	struct xfs_bmap_free	free_list;
 	xfs_fsblock_t		firstfsb;
-	xfs_bmap_free_t		free_list;
-	xfs_bmbt_irec_t		imap;
-	xfs_off_t		ioffset;
-	xfs_off_t		iendoffset;
-	xfs_extlen_t		mod=0;
-	xfs_mount_t		*mp;
-	int			nimap;
-	uint			resblks;
-	xfs_off_t		rounding;
-	int			rt;
-	xfs_fileoff_t		startoffset_fsb;
-	xfs_trans_t		*tp;
+	uint			resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
+	int			error;
 
-	mp = ip->i_mount;
+	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0, 0, &tp);
+	if (error) {
+		ASSERT(error == -ENOSPC || XFS_FORCED_SHUTDOWN(mp));
+		return error;
+	}
 
-	trace_xfs_free_file_space(ip);
+	xfs_ilock(ip, XFS_ILOCK_EXCL);
+	error = xfs_trans_reserve_quota(tp, mp, ip->i_udquot, ip->i_gdquot,
+			ip->i_pdquot, resblks, 0, XFS_QMOPT_RES_REGBLKS);
+	if (error)
+		goto out_trans_cancel;
 
-	error = xfs_qm_dqattach(ip, 0);
+	xfs_trans_ijoin(tp, ip, 0);
+
+	xfs_bmap_init(&free_list, &firstfsb);
+	error = xfs_bunmapi(tp, ip, startoffset_fsb, len_fsb, 0, 2, &firstfsb,
+			&free_list, done);
 	if (error)
-		return error;
+		goto out_bmap_cancel;
 
-	error = 0;
-	if (len <= 0)	/* if nothing being freed */
+	error = xfs_bmap_finish(&tp, &free_list, NULL);
+	if (error)
+		goto out_bmap_cancel;
+
+	error = xfs_trans_commit(tp);
+out_unlock:
+	xfs_iunlock(ip, XFS_ILOCK_EXCL);
 	return error;
-	rt = XFS_IS_REALTIME_INODE(ip);
-	startoffset_fsb	= XFS_B_TO_FSB(mp, offset);
-	endoffset_fsb = XFS_B_TO_FSBT(mp, offset + len);
 
-	/* wait for the completion of any pending DIOs */
-	inode_dio_wait(VFS_I(ip));
+out_bmap_cancel:
+	xfs_bmap_cancel(&free_list);
+out_trans_cancel:
+	xfs_trans_cancel(tp);
+	goto out_unlock;
+}
 
-	rounding = max_t(xfs_off_t, 1 << mp->m_sb.sb_blocklog, PAGE_SIZE);
-	ioffset = round_down(offset, rounding);
-	iendoffset = round_up(offset + len, rounding) - 1;
-	error = filemap_write_and_wait_range(VFS_I(ip)->i_mapping, ioffset,
-					     iendoffset);
-	if (error)
-		goto out;
-	truncate_pagecache_range(VFS_I(ip), ioffset, iendoffset);
+static int
+xfs_adjust_extent_unmap_boundaries(
+	struct xfs_inode	*ip,
+	xfs_fileoff_t		*startoffset_fsb,
+	xfs_fileoff_t		*endoffset_fsb)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_bmbt_irec	imap;
+	int			nimap, error;
+	xfs_extlen_t		mod = 0;
 
-	/*
-	 * Need to zero the stuff we're not freeing, on disk.
-	 * If it's a realtime file & can't use unwritten extents then we
-	 * actually need to zero the extent edges.  Otherwise xfs_bunmapi
-	 * will take care of it for us.
-	 */
-	if (rt && !xfs_sb_version_hasextflgbit(&mp->m_sb)) {
 	nimap = 1;
-		error = xfs_bmapi_read(ip, startoffset_fsb, 1,
-					&imap, &nimap, 0);
+	error = xfs_bmapi_read(ip, *startoffset_fsb, 1, &imap, &nimap, 0);
 	if (error)
-			goto out;
-		ASSERT(nimap == 0 || nimap == 1);
+		return error;
+
 	if (nimap && imap.br_startblock != HOLESTARTBLOCK) {
 		xfs_daddr_t	block;
 
@@ -1254,21 +1257,90 @@ xfs_free_file_space(
 		block = imap.br_startblock;
 		mod = do_div(block, mp->m_sb.sb_rextsize);
 		if (mod)
-				startoffset_fsb += mp->m_sb.sb_rextsize - mod;
+			*startoffset_fsb += mp->m_sb.sb_rextsize - mod;
 	}
+
 	nimap = 1;
-		error = xfs_bmapi_read(ip, endoffset_fsb - 1, 1,
-					&imap, &nimap, 0);
+	error = xfs_bmapi_read(ip, *endoffset_fsb - 1, 1, &imap, &nimap, 0);
 	if (error)
-			goto out;
-		ASSERT(nimap == 0 || nimap == 1);
+		return error;
+
 	if (nimap && imap.br_startblock != HOLESTARTBLOCK) {
 		ASSERT(imap.br_startblock != DELAYSTARTBLOCK);
 		mod++;
-			if (mod && (mod != mp->m_sb.sb_rextsize))
-				endoffset_fsb -= mod;
+		if (mod && mod != mp->m_sb.sb_rextsize)
+			*endoffset_fsb -= mod;
 	}
+
+	return 0;
+}
+
+static int
+xfs_flush_unmap_range(
+	struct xfs_inode	*ip,
+	xfs_off_t		offset,
+	xfs_off_t		len)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+	struct inode		*inode = VFS_I(ip);
+	xfs_off_t		rounding, start, end;
+	int			error;
+
+	/* wait for the completion of any pending DIOs */
+	inode_dio_wait(inode);
+
+	rounding = max_t(xfs_off_t, 1 << mp->m_sb.sb_blocklog, PAGE_SIZE);
+	start = round_down(offset, rounding);
+	end = round_up(offset + len, rounding) - 1;
+
+	error = filemap_write_and_wait_range(inode->i_mapping, start, end);
+	if (error)
+		return error;
+	truncate_pagecache_range(inode, start, end);
+	return 0;
+}
+
+int
+xfs_free_file_space(
+	struct xfs_inode	*ip,
+	xfs_off_t		offset,
+	xfs_off_t		len)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+	xfs_fileoff_t		startoffset_fsb;
+	xfs_fileoff_t		endoffset_fsb;
+	int			done, error;
+
+	trace_xfs_free_file_space(ip);
+
+	error = xfs_qm_dqattach(ip, 0);
+	if (error)
+		return error;
+
+	if (len <= 0)	/* if nothing being freed */
+		return 0;
+
+	error = xfs_flush_unmap_range(ip, offset, len);
+	if (error)
+		return error;
+
+	startoffset_fsb = XFS_B_TO_FSB(mp, offset);
+	endoffset_fsb = XFS_B_TO_FSBT(mp, offset + len);
+
+	/*
+	 * Need to zero the stuff we're not freeing, on disk.  If it's a RT file
+	 * and we can't use unwritten extents then we actually need to ensure
+	 * to zero the whole extent, otherwise we just need to take of block
+	 * boundaries, and xfs_bunmapi will handle the rest.
+	 */
+	if (XFS_IS_REALTIME_INODE(ip) &&
+	    !xfs_sb_version_hasextflgbit(&mp->m_sb)) {
+		error = xfs_adjust_extent_unmap_boundaries(ip, &startoffset_fsb,
+				&endoffset_fsb);
+		if (error)
+			return error;
 	}
+
 	if ((done = (endoffset_fsb <= startoffset_fsb)))
 		/*
 		 * One contiguous piece to clear
@@ -1288,62 +1360,12 @@ xfs_free_file_space(
 				offset + len - 1);
 	}
 
-	/*
-	 * free file space until done or until there is an error
-	 */
-	resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
 	while (!error && !done) {
-
-		/*
-		 * allocate and setup the transaction. Allow this
-		 * transaction to dip into the reserve blocks to ensure
-		 * the freeing of the space succeeds at ENOSPC.
-		 */
-		error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0, 0,
-				&tp);
-		if (error) {
-			ASSERT(error == -ENOSPC || XFS_FORCED_SHUTDOWN(mp));
-			break;
-		}
-		xfs_ilock(ip, XFS_ILOCK_EXCL);
-		error = xfs_trans_reserve_quota(tp, mp,
-				ip->i_udquot, ip->i_gdquot, ip->i_pdquot,
-				resblks, 0, XFS_QMOPT_RES_REGBLKS);
-		if (error)
-			goto error1;
-
-		xfs_trans_ijoin(tp, ip, 0);
-
-		/*
-		 * issue the bunmapi() call to free the blocks
-		 */
-		xfs_bmap_init(&free_list, &firstfsb);
-		error = xfs_bunmapi(tp, ip, startoffset_fsb,
-				  endoffset_fsb - startoffset_fsb,
-				  0, 2, &firstfsb, &free_list, &done);
-		if (error)
-			goto error0;
-
-		/*
-		 * complete the transaction
-		 */
-		error = xfs_bmap_finish(&tp, &free_list, NULL);
-		if (error)
-			goto error0;
-
-		error = xfs_trans_commit(tp);
-		xfs_iunlock(ip, XFS_ILOCK_EXCL);
+		error = xfs_unmap_extent(ip, startoffset_fsb,
+				endoffset_fsb - startoffset_fsb, &done);
 	}
 
- out:
 	return error;
-
- error0:
-	xfs_bmap_cancel(&free_list);
- error1:
-	xfs_trans_cancel(tp);
-	xfs_iunlock(ip, XFS_ILOCK_EXCL);
-	goto out;
 }
 
 /*