[BUGFIX] dnotify: handle_event shouldn't match on FS_EVENT_ON_CHILD

[BUGFIX] dnotify: handle_event shouldn't match on FS_EVENT_ON_CHILD

[Andreas Gruenbacher]

Mask off FS_EVENT_ON_CHILD in dnotify_handle_event().  Otherwise, when there
is more than one watch on a directory and dnotify_should_send_event()
succeeds, events with FS_EVENT_ON_CHILD set will trigger all watches and cause
spurious events.

This case was overlooked in commit e42e2773.

Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
---
 fs/notify/dnotify/dnotify.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/fs/notify/dnotify/dnotify.c b/fs/notify/dnotify/dnotify.c
index 828a889..0a8f1de 100644
--- a/fs/notify/dnotify/dnotify.c
+++ b/fs/notify/dnotify/dnotify.c
@@ -106,7 +106,7 @@ static int dnotify_handle_event(struct fsnotify_group *group,
 	spin_lock(&entry->lock);
 	prev = &dnentry->dn;
 	while ((dn = *prev) != NULL) {
-		if ((dn->dn_mask & event->mask) == 0) {
+		if ((dn->dn_mask & event->mask & ~FS_EVENT_ON_CHILD) == 0) {
 			prev = &dn->dn_next;
 			continue;
 		}
--

Re: [BUGFIX] dnotify: handle_event shouldn't match on FS_EVENT_ON_CHILD

[Andreas Gruenbacher]

Test case demonstrating the bug:


#define _GNU_SOURCE

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>

static void create_event(int s, siginfo_t* si, void* p)
{
	printf("create\n");
}

static void delete_event(int s, siginfo_t* si, void* p)
{
	printf("delete\n");
}

int main (void) {
	struct sigaction action;
	char *tmpdir, *file;
	int fd1, fd2;

	sigemptyset (&action.sa_mask);
	action.sa_flags = SA_SIGINFO;

	action.sa_sigaction = create_event;
	sigaction (SIGRTMIN + 0, &action, NULL);

	action.sa_sigaction = delete_event;
	sigaction (SIGRTMIN + 1, &action, NULL);

#	define TMPDIR "/tmp/test.XXXXXX"
	tmpdir = malloc(strlen(TMPDIR) + 1);
	strcpy(tmpdir, TMPDIR);
	mkdtemp(tmpdir);

#	define TMPFILE "file"
	file = malloc(strlen(tmpdir) + strlen(TMPFILE) + 2);
	sprintf(file, "%s/%s", tmpdir, TMPFILE);

	fd1 = open (tmpdir, O_RDONLY);
	fcntl(fd1, F_SETSIG, SIGRTMIN);
	fcntl(fd1, F_NOTIFY, DN_MULTISHOT | DN_CREATE);

	fd2 = open (tmpdir, O_RDONLY);
	fcntl(fd2, F_SETSIG, SIGRTMIN + 1);
	fcntl(fd2, F_NOTIFY, DN_MULTISHOT | DN_DELETE);

	if (fork()) {
		creat(file, 0600);

		/* Spurious event triggered below! */

		unlink(file);
	} else {
		sleep(1);
		rmdir(tmpdir);
	}

	return 0;
}

Re: [BUGFIX] dnotify: handle_event shouldn't match on FS_EVENT_ON_CHILD

[Eric Paris]

On Sun, 2009-10-18 at 14:46 +0200, Andreas Gruenbacher wrote:
> Mask off FS_EVENT_ON_CHILD in dnotify_handle_event().  Otherwise, when there
> is more than one watch on a directory and dnotify_should_send_event()
> succeeds, events with FS_EVENT_ON_CHILD set will trigger all watches and cause
> spurious events.

Added to my linus tree last night (along with a couple other fixes) will
push it public and ask him to pull when I finish testing.

-Eric

Re: [BUGFIX] dnotify: handle_event shouldn't match on FS_EVENT_ON_CHILD

[Andreas Gruenbacher]

On Sunday, 18 October 2009 17:52:10 Eric Paris wrote:
> Added to my linus tree last night (along with a couple other fixes) will
> push it public and ask him to pull when I finish testing.

Thanks.

Andreas