Commit 4ddd8bb1 authored by Lachlan McIlroy's avatar Lachlan McIlroy Committed by Niv Sardi
Browse files

[XFS] use minleft when allocating in xfs_bmbt_split() 



The bmap btree split code relies on a previous data extent allocation
(from xfs_bmap_btalloc()) to find an AG that has sufficient space to
perform a full btree split, when inserting the extent. When converting
unwritten extents we don't allocate a data extent so a btree split will be
the first allocation. In this case we need to set minleft so the allocator
will pick an AG that has space to complete the split(s).

SGI-PV: 983338

SGI-Modid: xfs-linux-melb:xfs-kern:31357a

Signed-off-by: default avatarLachlan McIlroy <lachlan@sgi.com>
Signed-off-by: default avatarDavid Chinner <dgc@sgi.com>
parent e182f57a

fs/xfs/xfs_bmap_btree.c

+14 −1
Original line number Diff line number Diff line
@@ -1493,12 +1493,25 @@ xfs_bmbt_split( 
	left = XFS_BUF_TO_BMBT_BLOCK(lbp);

	args.fsbno = cur->bc_private.b.firstblock;

	args.firstblock = args.fsbno;

	args.minleft = 0;

	if (args.fsbno == NULLFSBLOCK) {

		args.fsbno = lbno;

		args.type = XFS_ALLOCTYPE_START_BNO;

		/*

		 * Make sure there is sufficient room left in the AG to

		 * complete a full tree split for an extent insert.  If

		 * we are converting the middle part of an extent then

		 * we may need space for two tree splits.

		 *

		 * We are relying on the caller to make the correct block

		 * reservation for this operation to succeed.  If the

		 * reservation amount is insufficient then we may fail a

		 * block allocation here and corrupt the filesystem.

		 */

		args.minleft = xfs_trans_get_block_res(args.tp);

	} else

		args.type = XFS_ALLOCTYPE_NEAR_BNO;

	args.mod = args.minleft = args.alignment = args.total = args.isfl =

	args.mod = args.alignment = args.total = args.isfl =

		args.userdata = args.minalignslop = 0;

	args.minlen = args.maxlen = args.prod = 1;

	args.wasdel = cur->bc_private.b.flags & XFS_BTCUR_BPRV_WASDEL;

fs/xfs/xfs_iomap.c

+10 −0
Original line number Diff line number Diff line
@@ -889,6 +889,16 @@ xfs_iomap_write_unwritten( 
	count_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);

	count_fsb = (xfs_filblks_t)(count_fsb - offset_fsb);



	/*

	 * Reserve enough blocks in this transaction for two complete extent

	 * btree splits.  We may be converting the middle part of an unwritten

	 * extent and in this case we will insert two new extents in the btree

	 * each of which could cause a full split.

	 *

	 * This reservation amount will be used in the first call to

	 * xfs_bmbt_split() to select an AG with enough space to satisfy the

	 * rest of the operation.

	 */

	resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0) << 1;



	do {

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