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2010-10-28fanotify: allow fanotify to be builtEric Paris1-1/+1
We disabled the ability to build fanotify in commit 7c5347733dcc4ba0ba. This reverts that commit and allows people to build fanotify. Signed-off-by: Eric Paris <eparis@redhat.com>
2010-10-11fanotify: disable fanotify syscallsEric Paris1-1/+1
This patch disables the fanotify syscalls by just not building them and letting the cond_syscall() statements in kernel/sys_ni.c redirect them to sys_ni_syscall(). It was pointed out by Tvrtko Ursulin that the fanotify interface did not include an explicit prioritization between groups. This is necessary for fanotify to be usable for hierarchical storage management software, as they must get first access to the file, before inotify-like notifiers see the file. This feature can be added in an ABI compatible way in the next release (by using a number of bits in the flags field to carry the info) but it was suggested by Alan that maybe we should just hold off and do it in the next cycle, likely with an (new) explicit argument to the syscall. I don't like this approach best as I know people are already starting to use the current interface, but Alan is all wise and noone on list backed me up with just using what we have. I feel this is needlessly ripping the rug out from under people at the last minute, but if others think it needs to be a new argument it might be the best way forward. Three choices: Go with what we got (and implement the new feature next cycle). Add a new field right now (and implement the new feature next cycle). Wait till next cycle to release the ABI (and implement the new feature next cycle). This is number 3. Signed-off-by: Eric Paris <eparis@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-07-28fanotify: fscking all notification systemEric Paris1-0/+1
fanotify is a novel file notification system which bases notification on giving userspace both an event type (open, close, read, write) and an open file descriptor to the object in question. This should address a number of races and problems with other notification systems like inotify and dnotify and should allow the future implementation of blocking or access controlled notification. These are useful for on access scanners or hierachical storage management schemes. This patch just implements the basics of the fsnotify functions. Signed-off-by: Eric Paris <eparis@redhat.com>
2009-07-21fsnotify: use def_bool in kconfig instead of letting the user chooseEric Paris1-11/+1
fsnotify doens't give the user anything. If someone chooses inotify or dnotify it should build fsnotify, if they don't select one it shouldn't be built. This patch changes fsnotify to be a def_bool=n and makes everything else select it. Also fixes the issue people complained about on lwn where gdm hung because they didn't have inotify and they didn't get the inotify build option..... Signed-off-by: Eric Paris <eparis@redhat.com>
2009-06-11fsnotify: unified filesystem notification backendEric Paris1-0/+13
fsnotify is a backend for filesystem notification. fsnotify does not provide any userspace interface but does provide the basis needed for other notification schemes such as dnotify. fsnotify can be extended to be the backend for inotify or the upcoming fanotify. fsnotify provides a mechanism for "groups" to register for some set of filesystem events and to then deliver those events to those groups for processing. fsnotify has a number of benefits, the first being actually shrinking the size of an inode. Before fsnotify to support both dnotify and inotify an inode had unsigned long i_dnotify_mask; /* Directory notify events */ struct dnotify_struct *i_dnotify; /* for directory notifications */ struct list_head inotify_watches; /* watches on this inode */ struct mutex inotify_mutex; /* protects the watches list But with fsnotify this same functionallity (and more) is done with just __u32 i_fsnotify_mask; /* all events for this inode */ struct hlist_head i_fsnotify_mark_entries; /* marks on this inode */ That's right, inotify, dnotify, and fanotify all in 64 bits. We used that much space just in inotify_watches alone, before this patch set. fsnotify object lifetime and locking is MUCH better than what we have today. inotify locking is incredibly complex. See 8f7b0ba1c8539 as an example of what's been busted since inception. inotify needs to know internal semantics of superblock destruction and unmounting to function. The inode pinning and vfs contortions are horrible. no fsnotify implementers do allocation under locks. This means things like f04b30de3 which (due to an overabundance of caution) changes GFP_KERNEL to GFP_NOFS can be reverted. There are no longer any allocation rules when using or implementing your own fsnotify listener. fsnotify paves the way for fanotify. In brief fanotify is a notification mechanism that delivers the lisener both an 'event' and an open file descriptor to the object in question. This means that fanotify is pathname agnostic. Some on lkml may not care for the original companies or users that pushed for TALPA, but fanotify was designed with flexibility and input for other users in mind. The readahead group expressed interest in fanotify as it could be used to profile disk access on boot without breaking the audit system. The desktop search groups have also expressed interest in fanotify as it solves a number of the race conditions and problems present with managing inotify when more than a limited number of specific files are of interest. fanotify can provide for a userspace access control system which makes it a clean interface for AV vendors to hook without trying to do binary patching on the syscall table, LSM, and everywhere else they do their things today. With this patch series fanotify can be implemented in less than 1200 lines of easy to review code. Almost all of which is the socket based user interface. This patch series builds fsnotify to the point that it can implement dnotify and inotify_user. Patches exist and will be sent soon after acceptance to finish the in kernel inotify conversion (audit) and implement fanotify. Signed-off-by: Eric Paris <eparis@redhat.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@lst.de>
2008-12-31filesystem notification: create fs/notify to contain all fs notificationEric Paris1-0/+2
Creating a generic filesystem notification interface, fsnotify, which will be used by inotify, dnotify, and eventually fanotify is really starting to clutter the fs directory. This patch simply moves inotify and dnotify into fs/notify/inotify and fs/notify/dnotify respectively to make both current fs/ and future notification tidier. Signed-off-by: Eric Paris <eparis@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>