767cd46c33
fanotify listeners get an open file descriptor to the object in question so the ordering of operations is not as important as in other notification systems. inotify will drop events if the last event in the event FIFO is the same as the current event. This patch will drop fanotify events if they are the same as another event anywhere in the event FIFO. Signed-off-by: Eric Paris <eparis@redhat.com>
120 lines
3.1 KiB
C
120 lines
3.1 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->mask == new->mask) &&
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(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 *holder;
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struct fsnotify_event *test_event;
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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(holder, list, event_list) {
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test_event = holder->event;
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if (should_merge(test_event, event))
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return -EEXIST;
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}
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return 0;
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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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