Commit b8962a9d authored by Amir Goldstein's avatar Amir Goldstein Committed by Jan Kara
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nfsd: use fsnotify group lock helpers 

Before commit 9542e6a6 ("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/20220422120327.3459282-10-amir73il@gmail.com


Suggested-by: default avatarJan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220321112310.vpr7oxro2xkz5llh@quack3.lan/


Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
parent 960bdff2

fs/nfsd/filecache.c

+7 −6
Original line number Diff line number Diff line
@@ -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);

		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);
@@ -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));