[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: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: David Chinner <dgc@sgi.com>
diff --git a/fs/xfs/xfs_bmap_btree.c b/fs/xfs/xfs_bmap_btree.c
index 4aa2f11..3fc09cd 100644
--- a/fs/xfs/xfs_bmap_btree.c
+++ b/fs/xfs/xfs_bmap_btree.c
@@ -1493,12 +1493,25 @@
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;
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 7edcde6..67f22b2 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -889,6 +889,16 @@
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 {