From b8a6c3a2f0ae4d82732810e55ca8aa455e040bbf Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Wed, 8 Jul 2020 14:11:42 +0300 Subject: [PATCH] fanotify: create overflow event type The special overflow event is allocated as struct fanotify_path_event, but with a null path. Use a special event type to identify the overflow event, so the helper fanotify_has_event_path() will always indicate a non null path. Allocating the overflow event doesn't need any of the fancy stuff in fanotify_alloc_event(), so create a simplified helper for allocating the overflow event. There is also no need to store and report the pid with an overflow event. Link: https://lore.kernel.org/r/20200708111156.24659-7-amir73il@gmail.com Suggested-by: Jan Kara Signed-off-by: Amir Goldstein Signed-off-by: Jan Kara --- fs/notify/fanotify/fanotify.c | 27 +++++++++++---------------- fs/notify/fanotify/fanotify.h | 15 +++++++++------ fs/notify/fanotify/fanotify_user.c | 21 ++++++++++++++++----- 3 files changed, 36 insertions(+), 27 deletions(-) diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c index d9fc83d..921ff05 100644 --- a/fs/notify/fanotify/fanotify.c +++ b/fs/notify/fanotify/fanotify.c @@ -344,11 +344,11 @@ static struct inode *fanotify_fid_inode(struct inode *to_tell, u32 event_mask, return fsnotify_data_inode(data, data_type); } -struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group, - struct inode *inode, u32 mask, - const void *data, int data_type, - const struct qstr *file_name, - __kernel_fsid_t *fsid) +static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group, + struct inode *inode, u32 mask, + const void *data, int data_type, + const struct qstr *file_name, + __kernel_fsid_t *fsid) { struct fanotify_event *event = NULL; struct fanotify_fid_event *ffe = NULL; @@ -426,8 +426,7 @@ init: * event queue, so event reported on parent is merged with event * reported on child when both directory and child watches exist. */ - fsnotify_init_event(&event->fse, (unsigned long)id); - event->mask = mask; + fanotify_init_event(event, (unsigned long)id, mask); if (FAN_GROUP_FLAG(group, FAN_REPORT_TID)) event->pid = get_pid(task_pid(current)); else @@ -443,15 +442,8 @@ init: fanotify_encode_fh(fanotify_event_dir_fh(event), id, gfp); if (fanotify_event_has_path(event)) { - struct path *p = fanotify_event_path(event); - - if (path) { - *p = *path; - path_get(path); - } else { - p->mnt = NULL; - p->dentry = NULL; - } + *fanotify_event_path(event) = *path; + path_get(path); } out: memalloc_unuse_memcg(); @@ -640,6 +632,9 @@ static void fanotify_free_event(struct fsnotify_event *fsn_event) case FANOTIFY_EVENT_TYPE_FID_NAME: fanotify_free_name_event(event); break; + case FANOTIFY_EVENT_TYPE_OVERFLOW: + kfree(event); + break; default: WARN_ON_ONCE(1); } diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h index 8ce7ccf..1b2a3bb 100644 --- a/fs/notify/fanotify/fanotify.h +++ b/fs/notify/fanotify/fanotify.h @@ -63,6 +63,7 @@ enum fanotify_event_type { FANOTIFY_EVENT_TYPE_FID_NAME, /* variable length */ FANOTIFY_EVENT_TYPE_PATH, FANOTIFY_EVENT_TYPE_PATH_PERM, + FANOTIFY_EVENT_TYPE_OVERFLOW, /* struct fanotify_event */ }; struct fanotify_event { @@ -72,6 +73,14 @@ struct fanotify_event { struct pid *pid; }; +static inline void fanotify_init_event(struct fanotify_event *event, + unsigned long id, u32 mask) +{ + fsnotify_init_event(&event->fse, id); + event->mask = mask; + event->pid = NULL; +} + struct fanotify_fid_event { struct fanotify_event fae; __kernel_fsid_t fsid; @@ -202,9 +211,3 @@ static inline struct path *fanotify_event_path(struct fanotify_event *event) else return NULL; } - -struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group, - struct inode *inode, u32 mask, - const void *data, int data_type, - const struct qstr *file_name, - __kernel_fsid_t *fsid); diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c index d7f63ae..c9a824e 100644 --- a/fs/notify/fanotify/fanotify_user.c +++ b/fs/notify/fanotify/fanotify_user.c @@ -836,13 +836,26 @@ static int fanotify_add_inode_mark(struct fsnotify_group *group, FSNOTIFY_OBJ_TYPE_INODE, mask, flags, fsid); } +static struct fsnotify_event *fanotify_alloc_overflow_event(void) +{ + struct fanotify_event *oevent; + + oevent = kmalloc(sizeof(*oevent), GFP_KERNEL_ACCOUNT); + if (!oevent) + return NULL; + + fanotify_init_event(oevent, 0, FS_Q_OVERFLOW); + oevent->type = FANOTIFY_EVENT_TYPE_OVERFLOW; + + return &oevent->fse; +} + /* fanotify syscalls */ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) { struct fsnotify_group *group; int f_flags, fd; struct user_struct *user; - struct fanotify_event *oevent; pr_debug("%s: flags=%x event_f_flags=%x\n", __func__, flags, event_f_flags); @@ -897,13 +910,11 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) atomic_inc(&user->fanotify_listeners); group->memcg = get_mem_cgroup_from_mm(current->mm); - oevent = fanotify_alloc_event(group, NULL, FS_Q_OVERFLOW, NULL, - FSNOTIFY_EVENT_NONE, NULL, NULL); - if (unlikely(!oevent)) { + group->overflow_event = fanotify_alloc_overflow_event(); + if (unlikely(!group->overflow_event)) { fd = -ENOMEM; goto out_destroy_group; } - group->overflow_event = &oevent->fse; if (force_o_largefile()) event_f_flags |= O_LARGEFILE; -- 2.7.4