On Tue, Nov 16, 2010 at 02:12, Eric Paris <eparis@xxxxxxxxxx> wrote: > On Tue, 2010-11-16 at 02:03 +0300, Alexey Zaytsev wrote: >> On Tue, Nov 16, 2010 at 01:51, Eric Paris <eparis@xxxxxxxxxx> wrote: >> > On Tue, 2010-11-16 at 01:44 +0300, Alexey Zaytsev wrote: >> >> On Tue, Nov 16, 2010 at 01:11, Eric Paris <eparis@xxxxxxxxxx> wrote: >> >> > On Tue, 2010-11-16 at 01:05 +0300, Alexey Zaytsev wrote: >> >> >> Just some thoughts. >> >> >> >> >> >> Consider the situation: Files A and B both point to the same inode. >> >> >> File A is being watched, but the user won't get notifications if B is >> >> >> modified. >> >> > >> >> > That's not true. ÂUsers watch inodes, not files (this is true for both >> >> > inotify and fanotify). ÂGive it a try, it works. >> >> > >> >> >> >> debian-i386:~/tmp# touch a >> >> debian-i386:~/tmp# ../fanotify a & >> >> debian-i386:~/tmp# link a b >> >> debian-i386:~/tmp# ls -li >> >> total 0 >> >> 3433 -rw-r--r-- 2 root root 0 Nov 15 22:37 a >> >> 3433 -rw-r--r-- 2 root root 0 Nov 15 22:37 b >> >> debian-i386:~/tmp# echo 123 > b >> >> /root/tmp/b: pid=2143 mask = 20 open >> >> /root/tmp/b: pid=2143 mask = a modify 0 - 4 close(writable) Â0 - 4 >> >> >> >> Am I doing something wrong? Same thing happens if I watch the mount point. >> > >> > Maybe I don't understand the problem, you watched the inode behind A. >> > You made changes accessing this inode via B, you got notification about >> > those changes. ÂIsn't that what you wanted? >> >> I'd expect to get two notifications in this case. Might not be a >> problem when you are watching individual files, but there is no clear >> way to get all the modified files, if you are watching a mount point. > > Ah, you were hoping for 4 events. ÂYeah, not possible. ÂYou get notified > when the inode changes, which way you get notified is up to the kernel > and we leave it as an (impossible) exercise to userspace to map hard > linked inodes back together  :) > Yeah, I see now, it's impossible to get all the files linking to an inode even from the kernel space without scanning the fs. Thanks for the clarification. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
