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authorAmir Goldstein <amir73il@gmail.com>2022-04-22 15:03:21 +0300
committerJan Kara <jack@suse.cz>2022-04-25 15:37:34 +0300
commitaabb45fdcb31f00f1e7cae2bce83e83474a87c03 (patch)
tree04304237758daf38a68582bea664430e2a90bdf2 /fs/notify
parentb8962a9d8cc2d8c93362e2f684091c79f702f6f3 (diff)
downloadlinux-aabb45fdcb31f00f1e7cae2bce83e83474a87c03.tar.xz
dnotify: use fsnotify group lock helpers
Before commit 9542e6a643fc6 ("nfsd: Containerise filecache laundrette") nfsd would close open files in direct reclaim context. There is no guarantee that others memory shrinkers don't do the same and no guarantee that future shrinkers won't do that. For example, if overlayfs implements inode cache of fscache would keep open files to cached objects, inode shrinkers could end up closing open files to underlying fs. Direct reclaim from dnotify mark allocation context may try to close open files that have dnotify marks of the same group and hit a deadlock on mark_mutex. Set the FSNOTIFY_GROUP_NOFS flag to prevent going into direct reclaim from allocations under dnotify group lock and use the safe group lock helpers. Link: https://lore.kernel.org/r/20220422120327.3459282-11-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>
Diffstat (limited to 'fs/notify')
-rw-r--r--fs/notify/dnotify/dnotify.c13
1 files changed, 7 insertions, 6 deletions
diff --git a/fs/notify/dnotify/dnotify.c b/fs/notify/dnotify/dnotify.c
index e4779926edf4..190aa717fa32 100644
--- a/fs/notify/dnotify/dnotify.c
+++ b/fs/notify/dnotify/dnotify.c
@@ -168,7 +168,7 @@ void dnotify_flush(struct file *filp, fl_owner_t id)
return;
dn_mark = container_of(fsn_mark, struct dnotify_mark, fsn_mark);
- mutex_lock(&dnotify_group->mark_mutex);
+ fsnotify_group_lock(dnotify_group);
spin_lock(&fsn_mark->lock);
prev = &dn_mark->dn;
@@ -191,7 +191,7 @@ void dnotify_flush(struct file *filp, fl_owner_t id)
free = true;
}
- mutex_unlock(&dnotify_group->mark_mutex);
+ fsnotify_group_unlock(dnotify_group);
if (free)
fsnotify_free_mark(fsn_mark);
@@ -324,7 +324,7 @@ int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
new_dn_mark->dn = NULL;
/* this is needed to prevent the fcntl/close race described below */
- mutex_lock(&dnotify_group->mark_mutex);
+ fsnotify_group_lock(dnotify_group);
/* add the new_fsn_mark or find an old one. */
fsn_mark = fsnotify_find_mark(&inode->i_fsnotify_marks, dnotify_group);
@@ -334,7 +334,7 @@ int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
} else {
error = fsnotify_add_inode_mark_locked(new_fsn_mark, inode, 0);
if (error) {
- mutex_unlock(&dnotify_group->mark_mutex);
+ fsnotify_group_unlock(dnotify_group);
goto out_err;
}
spin_lock(&new_fsn_mark->lock);
@@ -383,7 +383,7 @@ out:
if (destroy)
fsnotify_detach_mark(fsn_mark);
- mutex_unlock(&dnotify_group->mark_mutex);
+ fsnotify_group_unlock(dnotify_group);
if (destroy)
fsnotify_free_mark(fsn_mark);
fsnotify_put_mark(fsn_mark);
@@ -401,7 +401,8 @@ static int __init dnotify_init(void)
SLAB_PANIC|SLAB_ACCOUNT);
dnotify_mark_cache = KMEM_CACHE(dnotify_mark, SLAB_PANIC|SLAB_ACCOUNT);
- dnotify_group = fsnotify_alloc_group(&dnotify_fsnotify_ops, 0);
+ dnotify_group = fsnotify_alloc_group(&dnotify_fsnotify_ops,
+ FSNOTIFY_GROUP_NOFS);
if (IS_ERR(dnotify_group))
panic("unable to allocate fsnotify group for dnotify\n");
dnotify_sysctl_init();