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nfsd: use fsnotify group lock helpers

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Before commit 9542e6a643 ("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: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220321112310.vpr7oxro2xkz5llh@quack3.lan/
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Amir Goldstein 2022-04-22 15:03:20 +03:00 committed by Jan Kara
parent 960bdff24c
commit b8962a9d8c
1 changed files with 7 additions and 6 deletions
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11
fs/nfsd/filecache.c
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@ -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));