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().
The lookup of fsnotify mark does not allocate memory so the nofs
variants of fsnotify group helpers are not needed.
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 | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
index 8bc807c5fea4..0a104e530934 100644
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c
@@ -118,14 +118,14 @@ 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;
@@ -133,8 +133,9 @@ 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);
@@ -613,6 +614,7 @@ nfsd_file_fsnotify_handle_event(struct fsnotify_mark *mark, u32 mask,
static const struct fsnotify_ops nfsd_file_fsnotify_ops = {
+ .group_flags = FSNOTIFY_GROUP_NOFS,
.handle_inode_event = nfsd_file_fsnotify_handle_event,
.free_mark = nfsd_file_mark_free,
};
--
2.25.1
