From: Greg KH Subject: Re: [RFC v2 1/4] fs: Add generic file system event notifications Date: Mon, 27 Apr 2015 16:24:21 +0200 Message-ID: <20150427142421.GB21942@kroah.com> References: <1430135504-24334-1-git-send-email-b.michalska@samsung.com> <1430135504-24334-2-git-send-email-b.michalska@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, jack@suse.cz, tytso@mit.edu, adilger.kernel@dilger.ca, hughd@google.com, lczerner@redhat.com, hch@infradead.org, linux-ext4@vger.kernel.org, linux-mm@kvack.org, kyungmin.park@samsung.com, kmpark@infradead.org To: Beata Michalska Return-path: Content-Disposition: inline In-Reply-To: <1430135504-24334-2-git-send-email-b.michalska@samsung.com> Sender: owner-linux-mm@kvack.org List-Id: linux-ext4.vger.kernel.org On Mon, Apr 27, 2015 at 01:51:41PM +0200, Beata Michalska wrote: > Introduce configurable generic interface for file > system-wide event notifications, to provide file > systems with a common way of reporting any potential > issues as they emerge. > > The notifications are to be issued through generic > netlink interface by newly introduced multicast group. > > Threshold notifications have been included, allowing > triggering an event whenever the amount of free space drops > below a certain level - or levels to be more precise as two > of them are being supported: the lower and the upper range. > The notifications work both ways: once the threshold level > has been reached, an event shall be generated whenever > the number of available blocks goes up again re-activating > the threshold. > > The interface has been exposed through a vfs. Once mounted, > it serves as an entry point for the set-up where one can > register for particular file system events. > > Signed-off-by: Beata Michalska > --- > Documentation/filesystems/events.txt | 231 ++++++++++ > fs/Makefile | 1 + > fs/events/Makefile | 6 + > fs/events/fs_event.c | 770 ++++++++++++++++++++++++++++++++++ > fs/events/fs_event.h | 25 ++ > fs/events/fs_event_netlink.c | 99 +++++ > fs/namespace.c | 1 + > include/linux/fs.h | 6 +- > include/linux/fs_event.h | 58 +++ > include/uapi/linux/fs_event.h | 54 +++ > include/uapi/linux/genetlink.h | 1 + > net/netlink/genetlink.c | 7 +- > 12 files changed, 1257 insertions(+), 2 deletions(-) > create mode 100644 Documentation/filesystems/events.txt > create mode 100644 fs/events/Makefile > create mode 100644 fs/events/fs_event.c > create mode 100644 fs/events/fs_event.h > create mode 100644 fs/events/fs_event_netlink.c > create mode 100644 include/linux/fs_event.h > create mode 100644 include/uapi/linux/fs_event.h Any reason why you just don't do uevents for the block devices today, and not create a new type of netlink message and userspace tool required to read these? > --- a/fs/Makefile > +++ b/fs/Makefile > @@ -126,3 +126,4 @@ obj-y += exofs/ # Multiple modules > obj-$(CONFIG_CEPH_FS) += ceph/ > obj-$(CONFIG_PSTORE) += pstore/ > obj-$(CONFIG_EFIVAR_FS) += efivarfs/ > +obj-y += events/ Always? > diff --git a/fs/events/Makefile b/fs/events/Makefile > new file mode 100644 > index 0000000..58d1454 > --- /dev/null > +++ b/fs/events/Makefile > @@ -0,0 +1,6 @@ > +# > +# Makefile for the Linux Generic File System Event Interface > +# > + > +obj-y := fs_event.o Always? Even if the option is not selected? Why is everyone forced to always use this code? Can't you disable it for the "tiny" systems that don't need it? > +struct fs_trace_entry { > + atomic_t count; Why not just use a 'struct kref' for your count, which will save a bunch of open-coding of reference counting, and forcing us to audit your code to verify you got all the corner cases correct? :) > + atomic_t active; > + struct super_block *sb; Are you properly reference counting this pointer? I didn't see where that was happening, so I must have missed it. thanks, greg k-h -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org