staging: lustre: llite: Fix the deadlock in balance_dirty_pages()

If the page is already dirtied in ll_write_end() and kernel tries
to call balance_dirty_pages() to write back dirty pages in the same
thread, this is deadlock case if the page is already held by clio.

This can also fix the issue of LU-4873.

Signed-off-by: Jinshan Xiong <jinshan.xiong@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-4977
Reviewed-on: http://review.whamcloud.com/10149
Reviewed-by: Bobi Jam <bobijam@gmail.com>
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/lustre/lustre/llite/rw26.c b/drivers/staging/lustre/lustre/llite/rw26.c
index c14a1b6805053e121f008288e080aa96e349e696..8c8c10044826481b0c06d6be762ec7f821323628 100644 (file)
--- a/drivers/staging/lustre/lustre/llite/rw26.c
+++ b/drivers/staging/lustre/lustre/llite/rw26.c
@@ -506,9 +506,8 @@ static int ll_write_begin(struct file *file, struct address_space *mapping,
        env = lcc->lcc_env;
        io  = lcc->lcc_io;
 
-       if (likely(to == PAGE_SIZE)) /* LU-4873 */
-               /* To avoid deadlock, try to lock page first. */
-               vmpage = grab_cache_page_nowait(mapping, index);
+       /* To avoid deadlock, try to lock page first. */
+       vmpage = grab_cache_page_nowait(mapping, index);
        if (unlikely(!vmpage || PageDirty(vmpage) || PageWriteback(vmpage))) {
                struct vvp_io *vio = vvp_env_io(env);
                struct cl_page_list *plist = &vio->u.write.vui_queue;
@@ -617,6 +616,13 @@ static int ll_write_end(struct file *file, struct address_space *mapping,
                        LASSERT(from == 0);
                vio->u.write.vui_to = from + copied;
 
+               /*
+                * To address the deadlock in balance_dirty_pages() where
+                * this dirty page may be written back in the same thread.
+                */
+               if (PageDirty(vmpage))
+                       unplug = true;
+
                /* We may have one full RPC, commit it soon */
                if (plist->pl_nr >= PTLRPC_MAX_BRW_PAGES)
                        unplug = true;