1 files changed, 39 insertions, 37 deletions

diff --git a/fs/xfs/xfs_bmap_btree.c b/fs/xfs/xfs_bmap_btree.c
index 4f0e849d973e..23efad29a5cd 100644
--- a/fs/xfs/xfs_bmap_btree.c
+++ b/fs/xfs/xfs_bmap_btree.c
@@ -1493,12 +1493,27 @@ 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;
-        } else
+                /*
+                 * 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 if (cur->bc_private.b.flist->xbf_low)
+                args.type = XFS_ALLOCTYPE_START_BNO;
+        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;
@@ -1510,6 +1525,21 @@ xfs_bmbt_split(
                 XFS_BMBT_TRACE_CURSOR(cur, ERROR);
                 return error;
         }
+        if (args.fsbno == NULLFSBLOCK && args.minleft) {
+                /*
+                 * Could not find an AG with enough free space to satisfy
+                 * a full btree split.  Try again without minleft and if
+                 * successful activate the lowspace algorithm.
+                 */
+                args.fsbno = 0;
+                args.type = XFS_ALLOCTYPE_FIRST_AG;
+                args.minleft = 0;
+                if ((error = xfs_alloc_vextent(&args))) {
+                        XFS_BMBT_TRACE_CURSOR(cur, ERROR);
+                        return error;
+                }
+                cur->bc_private.b.flist->xbf_low = 1;
+        }
         if (args.fsbno == NULLFSBLOCK) {
                 XFS_BMBT_TRACE_CURSOR(cur, EXIT);
                 *stat = 0;
@@ -2029,22 +2059,8 @@ xfs_bmbt_increment(
  * Insert the current record at the point referenced by cur.
  *
  * A multi-level split of the tree on insert will invalidate the original
- * cursor. It appears, however, that some callers assume that the cursor is
- * always valid. Hence if we do a multi-level split we need to revalidate the
- * cursor.
- *
- * When a split occurs, we will see a new cursor returned. Use that as a
- * trigger to determine if we need to revalidate the original cursor. If we get
- * a split, then use the original irec to lookup up the path of the record we
- * just inserted.
- *
- * Note that the fact that the btree root is in the inode means that we can
- * have the level of the tree change without a "split" occurring at the root
- * level. What happens is that the root is migrated to an allocated block and
- * the inode root is pointed to it. This means a single split can change the
- * level of the tree (level 2 -> level 3) and invalidate the old cursor. Hence
- * the level change should be accounted as a split so as to correctly trigger a
- * revalidation of the old cursor.
+ * cursor.  All callers of this function should assume that the cursor is
+ * no longer valid and revalidate it.
  */
 int                                     /* error */
 xfs_bmbt_insert(
@@ -2057,14 +2073,11 @@ xfs_bmbt_insert(
         xfs_fsblock_t   nbno;
         xfs_btree_cur_t *ncur;
         xfs_bmbt_rec_t  nrec;
-        xfs_bmbt_irec_t oirec;          /* original irec */
         xfs_btree_cur_t *pcur;
-        int             splits = 0;
 
         XFS_BMBT_TRACE_CURSOR(cur, ENTRY);
         level = 0;
         nbno = NULLFSBLOCK;
-        oirec = cur->bc_rec.b;
         xfs_bmbt_disk_set_all(&nrec, &cur->bc_rec.b);
         ncur = NULL;
         pcur = cur;
@@ -2073,13 +2086,11 @@ xfs_bmbt_insert(
                                 &i))) {
                         if (pcur != cur)
                                 xfs_btree_del_cursor(pcur, XFS_BTREE_ERROR);
-                        goto error0;
+                        XFS_BMBT_TRACE_CURSOR(cur, ERROR);
+                        return error;
                 }
                 XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
                 if (pcur != cur && (ncur || nbno == NULLFSBLOCK)) {
-                        /* allocating a new root is effectively a split */
-                        if (cur->bc_nlevels != pcur->bc_nlevels)
-                                splits++;
                         cur->bc_nlevels = pcur->bc_nlevels;
                         cur->bc_private.b.allocated +=
                                 pcur->bc_private.b.allocated;
@@ -2093,21 +2104,10 @@ xfs_bmbt_insert(
                         xfs_btree_del_cursor(pcur, XFS_BTREE_NOERROR);
                 }
                 if (ncur) {
-                        splits++;
                         pcur = ncur;
                         ncur = NULL;
                 }
         } while (nbno != NULLFSBLOCK);
-
-        if (splits > 1) {
-                /* revalidate the old cursor as we had a multi-level split */
-                error = xfs_bmbt_lookup_eq(cur, oirec.br_startoff,
-                                oirec.br_startblock, oirec.br_blockcount, &i);
-                if (error)
-                        goto error0;
-                ASSERT(i == 1);
-        }
-
         XFS_BMBT_TRACE_CURSOR(cur, EXIT);
         *stat = i;
         return 0;
@@ -2254,7 +2254,9 @@ xfs_bmbt_newroot(
 #endif
                 args.fsbno = be64_to_cpu(*pp);
                 args.type = XFS_ALLOCTYPE_START_BNO;
-        } else
+        } else if (cur->bc_private.b.flist->xbf_low)
+                args.type = XFS_ALLOCTYPE_START_BNO;
+        else
                 args.type = XFS_ALLOCTYPE_NEAR_BNO;
         if ((error = xfs_alloc_vextent(&args))) {
                 XFS_BMBT_TRACE_CURSOR(cur, ERROR);