nfsd: use fsnotify group lock helpers

Before commit 9542e6a ("nfsd: Containerise filecache laundrette") nfsd would close open files in direct reclaim context and that could cause a deadlock when fsnotify mark allocation went into direct reclaim and nfsd shrinker tried to free existing fsnotify marks. To avoid issues like this in future code, set the FSNOTIFY_GROUP_NOFS flag on nfsd fsnotify group to prevent going into direct reclaim from fsnotify_add_inode_mark(). Link: https://lore.kernel.org/r/[email protected] Suggested-by: Jan Kara <[email protected]> Link: https://lore.kernel.org/r/[email protected]/ Signed-off-by: Amir Goldstein <[email protected]> Signed-off-by: Jan Kara <[email protected]>
rountree · Apr 25, 2022 · b8962a9 · b8962a9
1 parent 960bdff
commit b8962a9
Showing 1 changed file with 7 additions and 6 deletions.
diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
@@ -119,23 +119,24 @@ nfsd_file_mark_find_or_create(struct nfsd_file *nf)
 	struct inode *inode = nf->nf_inode;
 
 	do {
-		mutex_lock(&nfsd_file_fsnotify_group->mark_mutex);
+		fsnotify_group_lock(nfsd_file_fsnotify_group);
 		mark = fsnotify_find_mark(&inode->i_fsnotify_marks,
-				nfsd_file_fsnotify_group);
+					  nfsd_file_fsnotify_group);
 		if (mark) {
 			nfm = nfsd_file_mark_get(container_of(mark,
 						 struct nfsd_file_mark,
 						 nfm_mark));
-			mutex_unlock(&nfsd_file_fsnotify_group->mark_mutex);
+			fsnotify_group_unlock(nfsd_file_fsnotify_group);
 			if (nfm) {
 				fsnotify_put_mark(mark);
 				break;
 			}
 			/* Avoid soft lockup race with nfsd_file_mark_put() */
 			fsnotify_destroy_mark(mark, nfsd_file_fsnotify_group);
 			fsnotify_put_mark(mark);
-		} else
-			mutex_unlock(&nfsd_file_fsnotify_group->mark_mutex);
+		} else {
+			fsnotify_group_unlock(nfsd_file_fsnotify_group);
+		}
 
 		/* allocate a new nfm */
 		new = kmem_cache_alloc(nfsd_file_mark_slab, GFP_KERNEL);
@@ -679,7 +680,7 @@ nfsd_file_cache_init(void)
 	}
 
 	nfsd_file_fsnotify_group = fsnotify_alloc_group(&nfsd_file_fsnotify_ops,
-							0);
+							FSNOTIFY_GROUP_NOFS);
 	if (IS_ERR(nfsd_file_fsnotify_group)) {
 		pr_err("nfsd: unable to create fsnotify group: %ld\n",
 			PTR_ERR(nfsd_file_fsnotify_group));