1 files changed, 25 insertions, 3 deletions

diff --git a/fs/xfs/xfs_alloc.c b/fs/xfs/xfs_alloc.c
index acdced86413c..721db22c6ec9 100644
--- a/fs/xfs/xfs_alloc.c
+++ b/fs/xfs/xfs_alloc.c
@@ -2609,6 +2609,18 @@ xfs_alloc_busy_update_extent(
         xfs_agblock_t           bend = bbno + busyp->length;
 
         /*
+         * This extent is currently being discarded.  Give the thread
+         * performing the discard a chance to mark the extent unbusy
+         * and retry.
+         */
+        if (busyp->flags & XFS_ALLOC_BUSY_DISCARDED) {
+                spin_unlock(&pag->pagb_lock);
+                delay(1);
+                spin_lock(&pag->pagb_lock);
+                return false;
+        }
+
+        /*
          * If there is a busy extent overlapping a user allocation, we have
          * no choice but to force the log and retry the search.
          *
@@ -2813,7 +2825,8 @@ restart:
                  * If this is a metadata allocation, try to reuse the busy
                  * extent instead of trimming the allocation.
                  */
-                if (!args->userdata) {
+                if (!args->userdata &&
+                    !(busyp->flags & XFS_ALLOC_BUSY_DISCARDED)) {
                         if (!xfs_alloc_busy_update_extent(args->mp, args->pag,
                                                           busyp, fbno, flen,
                                                           false))
@@ -2979,10 +2992,16 @@ xfs_alloc_busy_clear_one(
         kmem_free(busyp);
 }
 
+/*
+ * Remove all extents on the passed in list from the busy extents tree.
+ * If do_discard is set skip extents that need to be discarded, and mark
+ * these as undergoing a discard operation instead.
+ */
 void
 xfs_alloc_busy_clear(
         struct xfs_mount        *mp,
-        struct list_head        *list)
+        struct list_head        *list,
+        bool                    do_discard)
 {
         struct xfs_busy_extent  *busyp, *n;
         struct xfs_perag        *pag = NULL;
@@ -2999,7 +3018,10 @@ xfs_alloc_busy_clear(
                         agno = busyp->agno;
                 }
 
-                xfs_alloc_busy_clear_one(mp, pag, busyp);
+                if (do_discard && busyp->length)
+                        busyp->flags = XFS_ALLOC_BUSY_DISCARDED;
+                else
+                        xfs_alloc_busy_clear_one(mp, pag, busyp);
         }
 
         if (pag) {