bcachefs: Fix dio write path with loopback dio mode

When the iov_iter is a bvec iter, it's possible the IO was submitted
from a kthread that didn't have an mm to switch to.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

diff --git a/fs/bcachefs/fs-io.c b/fs/bcachefs/fs-io.c
index 8231c29a753470b553c3ff1b2dd6295755ead0c5..77a893260fd8bef98314734b10e3fa7d30788998 100644 (file)
--- a/fs/bcachefs/fs-io.c
+++ b/fs/bcachefs/fs-io.c
@@ -2110,7 +2110,7 @@ static long bch2_dio_write_loop(struct dio_write *dio)
        while (1) {
                iter_count = dio->iter.count;
 
-               if (kthread)
+               if (kthread && dio->mm)
                        kthread_use_mm(dio->mm);
                BUG_ON(current->faults_disabled_mapping);
                current->faults_disabled_mapping = mapping;
@@ -2120,7 +2120,7 @@ static long bch2_dio_write_loop(struct dio_write *dio)
                dropped_locks = fdm_dropped_locks();
 
                current->faults_disabled_mapping = NULL;
-               if (kthread)
+               if (kthread && dio->mm)
                        kthread_unuse_mm(dio->mm);
 
                /*