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fsnotify: Detach mark from object list when last reference is dropped

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Instead of removing mark from object list from fsnotify_detach_mark(),
remove the mark when last reference to the mark is dropped. This will
allow fanotify to wait for userspace response to event without having to
hold onto fsnotify_mark_srcu.

To avoid pinning inodes by elevated refcount (and thus e.g. delaying
file deletion) while someone holds mark reference, we detach connector
from the object also from fsnotify_destroy_marks() and not only after
removing last mark from the list as it was now.

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Jan Kara
2016-12-21 12:15:30 +01:00
parent 11375145a7
commit 6b3f05d24d
3 changed files with 106 additions and 78 deletions
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4
include/linux/fsnotify_backend.h
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@@ -245,9 +245,9 @@ struct fsnotify_mark {
struct list_head g_list;
/* Protects inode / mnt pointers, flags, masks */
spinlock_t lock;
/* List of marks for inode / vfsmount [connector->lock] */
/* List of marks for inode / vfsmount [connector->lock, mark ref] */
struct hlist_node obj_list;
/* Head of list of marks for an object [mark->lock, group->mark_mutex] */
/* Head of list of marks for an object [mark ref] */
struct fsnotify_mark_connector *connector;
/* Events types to ignore [mark->lock, group->mark_mutex] */
__u32 ignored_mask;