Before commit 9542e6a643fc6 ("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().
Suggested-by: Jan Kara <jack@xxxxxxx>
Link: https://lore.kernel.org/r/20220321112310.vpr7oxro2xkz5llh@xxxxxxxxxx/
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/nfsd/filecache.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
index 79a5b052fcdf..258599db119f 100644
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c
@@ -119,14 +119,14 @@ 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;
@@ -134,8 +134,9 @@ nfsd_file_mark_find_or_create(struct nfsd_file *nf)
/* 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);
@@ -674,7 +675,7 @@ 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));
--
2.35.1
