Annotate KM_PUSHPAGE call paths with PF_NOFS

[zfs.git] / module / zfs / zvol.c

diff --git a/module/zfs/zvol.c b/module/zfs/zvol.c
index 07bda6d..60ff64e 100644 (file)
--- a/module/zfs/zvol.c
+++ b/module/zfs/zvol.c
@@ -540,6 +540,14 @@ zvol_write(void *arg)
        dmu_tx_t *tx;
        rl_t *rl;
 
+       /*
+        * Annotate this call path with a flag that indicates that it is
+        * unsafe to use KM_SLEEP during memory allocations due to the
+        * potential for a deadlock.  KM_PUSHPAGE should be used instead.
+        */
+       ASSERT(!(current->flags & PF_NOFS));
+       current->flags |= PF_NOFS;
+
        if (req->cmd_flags & VDEV_REQ_FLUSH)
                zil_commit(zv->zv_zilog, ZVOL_OBJ);
 
@@ -548,7 +556,7 @@ zvol_write(void *arg)
         */
        if (size == 0) {
                blk_end_request(req, 0, size);
-               return;
+               goto out;
        }
 
        rl = zfs_range_lock(&zv->zv_znode, offset, size, RL_WRITER);
@@ -562,7 +570,7 @@ zvol_write(void *arg)
                dmu_tx_abort(tx);
                zfs_range_unlock(rl);
                blk_end_request(req, -error, size);
-               return;
+               goto out;
        }
 
        error = dmu_write_req(zv->zv_objset, ZVOL_OBJ, req, tx);
@@ -578,6 +586,8 @@ zvol_write(void *arg)
                zil_commit(zv->zv_zilog, ZVOL_OBJ);
 
        blk_end_request(req, -error, size);
+out:
+       current->flags &= ~PF_NOFS;
 }
 
 #ifdef HAVE_BLK_QUEUE_DISCARD
@@ -592,14 +602,22 @@ zvol_discard(void *arg)
        int error;
        rl_t *rl;
 
+       /*
+        * Annotate this call path with a flag that indicates that it is
+        * unsafe to use KM_SLEEP during memory allocations due to the
+        * potential for a deadlock.  KM_PUSHPAGE should be used instead.
+        */
+       ASSERT(!(current->flags & PF_NOFS));
+       current->flags |= PF_NOFS;
+
        if (offset + size > zv->zv_volsize) {
                blk_end_request(req, -EIO, size);
-               return;
+               goto out;
        }
 
        if (size == 0) {
                blk_end_request(req, 0, size);
-               return;
+               goto out;
        }
 
        rl = zfs_range_lock(&zv->zv_znode, offset, size, RL_WRITER);
@@ -613,6 +631,8 @@ zvol_discard(void *arg)
        zfs_range_unlock(rl);
 
        blk_end_request(req, -error, size);
+out:
+       current->flags &= ~PF_NOFS;
 }
 #endif /* HAVE_BLK_QUEUE_DISCARD */