a12a7dd328
Instead of just merging fanotify events if they are exactly the same, merge notification events with different masks. To do this we have to clone the old event, update the mask in the new event with the new merged mask, and put the new event in place of the old event. Signed-off-by: Eric Paris <eparis@redhat.com>
141 lines
3.7 KiB
C
141 lines
3.7 KiB
C
#include <linux/fdtable.h>
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#include <linux/fsnotify_backend.h>
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#include <linux/init.h>
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#include <linux/kernel.h> /* UINT_MAX */
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#include <linux/types.h>
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#include "fanotify.h"
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static bool should_merge(struct fsnotify_event *old, struct fsnotify_event *new)
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{
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pr_debug("%s: old=%p new=%p\n", __func__, old, new);
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if ((old->to_tell == new->to_tell) &&
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(old->data_type == new->data_type)) {
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switch (old->data_type) {
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case (FSNOTIFY_EVENT_PATH):
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if ((old->path.mnt == new->path.mnt) &&
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(old->path.dentry == new->path.dentry))
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return true;
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case (FSNOTIFY_EVENT_NONE):
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return true;
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default:
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BUG();
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};
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}
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return false;
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}
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static int fanotify_merge(struct list_head *list, struct fsnotify_event *event)
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{
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struct fsnotify_event_holder *test_holder;
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struct fsnotify_event *test_event;
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struct fsnotify_event *new_event;
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int ret = 0;
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pr_debug("%s: list=%p event=%p\n", __func__, list, event);
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/* and the list better be locked by something too! */
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list_for_each_entry_reverse(test_holder, list, event_list) {
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test_event = test_holder->event;
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if (should_merge(test_event, event)) {
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ret = -EEXIST;
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/* if they are exactly the same we are done */
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if (test_event->mask == event->mask)
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goto out;
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/* can't allocate memory, merge was no possible */
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new_event = fsnotify_clone_event(test_event);
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if (unlikely(!new_event)) {
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ret = 0;
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goto out;
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}
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/* build new event and replace it on the list */
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new_event->mask = (test_event->mask | event->mask);
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fsnotify_replace_event(test_holder, new_event);
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/* match ref from fsnotify_clone_event() */
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fsnotify_put_event(new_event);
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break;
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}
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}
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out:
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return ret;
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}
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static int fanotify_handle_event(struct fsnotify_group *group, struct fsnotify_event *event)
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{
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int ret;
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BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS);
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BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY);
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BUILD_BUG_ON(FAN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE);
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BUILD_BUG_ON(FAN_CLOSE_WRITE != FS_CLOSE_WRITE);
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BUILD_BUG_ON(FAN_OPEN != FS_OPEN);
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BUILD_BUG_ON(FAN_EVENT_ON_CHILD != FS_EVENT_ON_CHILD);
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BUILD_BUG_ON(FAN_Q_OVERFLOW != FS_Q_OVERFLOW);
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pr_debug("%s: group=%p event=%p\n", __func__, group, event);
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ret = fsnotify_add_notify_event(group, event, NULL, fanotify_merge);
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/* -EEXIST means this event was merged with another, not that it was an error */
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if (ret == -EEXIST)
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ret = 0;
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return ret;
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}
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static bool fanotify_should_send_event(struct fsnotify_group *group, struct inode *inode,
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struct vfsmount *mnt, __u32 mask, void *data,
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int data_type)
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{
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struct fsnotify_mark *fsn_mark;
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bool send;
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pr_debug("%s: group=%p inode=%p mask=%x data=%p data_type=%d\n",
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__func__, group, inode, mask, data, data_type);
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/* sorry, fanotify only gives a damn about files and dirs */
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if (!S_ISREG(inode->i_mode) &&
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!S_ISDIR(inode->i_mode))
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return false;
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/* if we don't have enough info to send an event to userspace say no */
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if (data_type != FSNOTIFY_EVENT_PATH)
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return false;
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fsn_mark = fsnotify_find_mark(group, inode);
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if (!fsn_mark)
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return false;
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/* if the event is for a child and this inode doesn't care about
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* events on the child, don't send it! */
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if ((mask & FS_EVENT_ON_CHILD) &&
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!(fsn_mark->mask & FS_EVENT_ON_CHILD)) {
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send = false;
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} else {
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/*
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* We care about children, but do we care about this particular
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* type of event?
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*/
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mask = (mask & ~FS_EVENT_ON_CHILD);
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send = (fsn_mark->mask & mask);
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}
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/* find took a reference */
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fsnotify_put_mark(fsn_mark);
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return send;
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}
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const struct fsnotify_ops fanotify_fsnotify_ops = {
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.handle_event = fanotify_handle_event,
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.should_send_event = fanotify_should_send_event,
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.free_group_priv = NULL,
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.free_event_priv = NULL,
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.freeing_mark = NULL,
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};
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