Christoph Lameter a écrit : > On Fri, 12 Dec 2008, Eric Dumazet wrote: > >>> a truly allocated file. At this point the file is >>> a truly allocated file but not anymore ours. > > Its a valid file. Does ownership matter here? > >> Reading again this mail I realise we call put_filp(file), while this should >> be fput(file) or put_filp(file), we dont know. >> >> Damned, this patch is wrong as is. >> >> Christoph, Paul, do you see the problem ? > > Yes. > >> In fget()/fget_light() we dont know if the other thread (the one who re-allocated the file, >> and tried to close it while we got a reference on file) had to call put_filp() or fput() >> to release its own reference. So we call atomic_long_dec_and_test() and cannot >> take the appropriate action (calling the full __fput() version or the small one, >> that some systems use to 'close' an not really opened file. > > The difference is mainly that fput() does full processing whereas > put_filp() is used when we know that the file was not fully operational. > If the checks in __fput are able to handle the put_filp() situation by not > releasing resources that were not allocated then we should be fine. > >> I believe put_filp() is only called on slowpath (error cases). > > Looks like it. It seems to assume that no dentry is associated. > >> Should we just zap it and always call fput() ? > > Only if fput() can handle partially setup files. It can do that if we add a check for NULL dentry in __fput(), so put_filp() can disappear. But there is a remaining point where we do an atomic_long_dec_and_test(&...->f_count), in fs/aio.c, function __aio_put_req(). This one is tricky :( -- 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
