1 files changed, 54 insertions, 19 deletions

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index b48abc300c36..6de613b558a9 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -4721,6 +4721,47 @@ error0:
 }
 
 /*
+ * When a delalloc extent is split (e.g., due to a hole punch), the original
+ * indlen reservation must be shared across the two new extents that are left
+ * behind.
+ *
+ * Given the original reservation and the worst case indlen for the two new
+ * extents (as calculated by xfs_bmap_worst_indlen()), split the original
+ * reservation fairly across the two new extents.
+ */
+static void
+xfs_bmap_split_indlen(
+        xfs_filblks_t                   ores,           /* original res. */
+        xfs_filblks_t                   *indlen1,       /* ext1 worst indlen */
+        xfs_filblks_t                   *indlen2)       /* ext2 worst indlen */
+{
+        xfs_filblks_t                   len1 = *indlen1;
+        xfs_filblks_t                   len2 = *indlen2;
+        xfs_filblks_t                   nres = len1 + len2; /* new total res. */
+
+        /*
+         * The only blocks available are those reserved for the original extent.
+         * Therefore, we have to skim blocks off each of the new reservations so
+         * long as the new total reservation is greater than the original.
+         */
+        while (nres > ores) {
+                if (len1) {
+                        len1--;
+                        nres--;
+                }
+                if (nres == ores)
+                        break;
+                if (len2) {
+                        len2--;
+                        nres--;
+                }
+        }
+
+        *indlen1 = len1;
+        *indlen2 = len2;
+}
+
+/*
  * Called by xfs_bmapi to update file extent records and the btree
  * after removing space (or undoing a delayed allocation).
  */
@@ -4985,27 +5026,21 @@ xfs_bmap_del_extent(
                                 XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
                 } else {
                         ASSERT(whichfork == XFS_DATA_FORK);
-                        temp = xfs_bmap_worst_indlen(ip, temp);
+
+                        /*
+                         * Distribute the original indlen reservation across the
+                         * two new extents.
+                         */
+                        temp = xfs_bmap_worst_indlen(ip, got.br_blockcount);
+                        temp2 = xfs_bmap_worst_indlen(ip, new.br_blockcount);
+                        xfs_bmap_split_indlen(da_old, &temp, &temp2);
+                        da_new = temp + temp2;
+
+                        /*
+                         * Set the reservation for each extent.
+                         */
                         xfs_bmbt_set_startblock(ep, nullstartblock((int)temp));
-                        temp2 = xfs_bmap_worst_indlen(ip, temp2);
                         new.br_startblock = nullstartblock((int)temp2);
-                        da_new = temp + temp2;
-                        while (da_new > da_old) {
-                                if (temp) {
-                                        temp--;
-                                        da_new--;
-                                        xfs_bmbt_set_startblock(ep,
-                                                nullstartblock((int)temp));
-                                }
-                                if (da_new == da_old)
-                                        break;
-                                if (temp2) {
-                                        temp2--;
-                                        da_new--;
-                                        new.br_startblock =
-                                                nullstartblock((int)temp2);
-                                }
-                        }
                 }
                 trace_xfs_bmap_post_update(ip, *idx, state, _THIS_IP_);
                 xfs_iext_insert(ip, *idx + 1, 1, &new, state);