LU-4198 clio: turn on lockless for some kind of IO

[fs/lustre-release.git] / lustre / llite / rw26.c

diff --git a/lustre/llite/rw26.c b/lustre/llite/rw26.c
index 6f2bb6c..ab6bec9 100644 (file)
--- a/lustre/llite/rw26.c
+++ b/lustre/llite/rw26.c
@@ -672,14 +672,25 @@ static int ll_write_begin(struct file *file, struct address_space *mapping,
        env = lcc->lcc_env;
        io  = lcc->lcc_io;
 
-       if (file->f_flags & O_DIRECT && io->ci_designated_mirror > 0) {
+       if (file->f_flags & O_DIRECT) {
                /* direct IO failed because it couldn't clean up cached pages,
                 * this causes a problem for mirror write because the cached
                 * page may belong to another mirror, which will result in
                 * problem submitting the I/O. */
-               GOTO(out, result = -EBUSY);
-       }
+               if (io->ci_designated_mirror > 0)
+                       GOTO(out, result = -EBUSY);
 
+               /**
+                * Direct read can fall back to buffered read, but DIO is done
+                * with lockless i/o, and buffered requires LDLM locking, so
+                * in this case we must restart without lockless.
+                */
+               if (!io->ci_ignore_lockless) {
+                       io->ci_ignore_lockless = 1;
+                       io->ci_need_restart = 1;
+                       GOTO(out, result = -ENOLCK);
+               }
+       }
 again:
        /* To avoid deadlock, try to lock page first. */
        vmpage = grab_cache_page_nowait(mapping, index);