There are many places in the kernel where the construction like
foo = list_entry(head->next, struct foo_struct, list);
are used.
The code might look more descriptive and neat if using the macro
list_first_entry(head, type, member) \
list_entry((head)->next, type, member)
Here is the macro itself and the examples of its usage in the generic code.
If it will turn out to be useful, I can prepare the set of patches to
inject in into arch-specific code, drivers, networking, etc.
Signed-off-by: Pavel Emelianov <xemul@openvz.org>
Signed-off-by: Kirill Korotaev <dev@openvz.org>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Zach Brown <zach.brown@oracle.com>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: John McCutchan <ttb@tentacle.dhs.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Allow callers to remove watches from their event handler via
inotify_remove_watch_locked(). This functionality can be used to
achieve IN_ONESHOT-like functionality for a subset of events in the
mask.
Signed-off-by: Amy Griffis <amy.griffis@hp.com>
Acked-by: Robert Love <rml@novell.com>
Acked-by: John McCutchan <john@johnmccutchan.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Add inotify_init_watch() so caller can use inotify_watch refcounts
before calling inotify_add_watch().
Add inotify_find_watch() to find an existing watch for an (ih,inode)
pair. This is similar to inotify_find_update_watch(), but does not
update the watch's mask if one is found.
Add inotify_rm_watch() to remove a watch via the watch pointer instead
of the watch descriptor.
Signed-off-by: Amy Griffis <amy.griffis@hp.com>
Acked-by: Robert Love <rml@novell.com>
Acked-by: John McCutchan <john@johnmccutchan.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
When an inotify event includes a dentry name, also include the inode
associated with that name.
Signed-off-by: Amy Griffis <amy.griffis@hp.com>
Acked-by: Robert Love <rml@novell.com>
Acked-by: John McCutchan <john@johnmccutchan.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The following series of patches introduces a kernel API for inotify,
making it possible for kernel modules to benefit from inotify's
mechanism for watching inodes. With these patches, inotify will
maintain for each caller a list of watches (via an embedded struct
inotify_watch), where each inotify_watch is associated with a
corresponding struct inode. The caller registers an event handler and
specifies for which filesystem events their event handler should be
called per inotify_watch.
Signed-off-by: Amy Griffis <amy.griffis@hp.com>
Acked-by: Robert Love <rml@novell.com>
Acked-by: John McCutchan <john@johnmccutchan.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Don't reassign to watch. If idr_find() returns NULL, then
put_inotify_watch() will choke.
Signed-off-by: Amy Griffis <amy.griffis@hp.com>
Cc: John McCutchan <john@johnmccutchan.com>
Cc: Robert Love <rlove@rlove.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
While doing some inotify stress testing, I hit the following race. In
inotify_release(), it's possible for a watch to be removed from the lists
in between dropping dev->mutex and taking inode->inotify_mutex. The
reference we hold prevents the watch from being freed, but not from being
removed.
Checking the dev's idr mapping will prevent a double list_del of the
same watch.
Signed-off-by: Amy Griffis <amy.griffis@hp.com>
Acked-by: John McCutchan <john@johnmccutchan.com>
Cc: Robert Love <rml@novell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The spufs file system creates files in a directory before instantiating the
directory itself, which causes a NULL pointer access in
inotify_d_instantiate since c32ccd87bf.
I'd like to keep this behavior since it means that the user will not have
access to files in the directory before I know that I succeed in creating
everything in it. This patch adds a simple check for the inode to keep
that working.
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Acked-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This is a conversion to make the various file_operations structs in fs/
const. Basically a regexp job, with a few manual fixups
The goal is both to increase correctness (harder to accidentally write to
shared datastructures) and reducing the false sharing of cachelines with
things that get dirty in .data (while .rodata is nicely read only and thus
cache clean)
Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
I discovered on oprofile hunting on a SMP platform that dentry lookups were
slowed down because d_hash_mask, d_hash_shift and dentry_hashtable were in
a cache line that contained inodes_stat. So each time inodes_stats is
changed by a cpu, other cpus have to refill their cache line.
This patch moves some variables to the __read_mostly section, in order to
avoid false sharing. RCU dentry lookups can go full speed.
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Previous inotify work avoidance is good when inotify is completely unused,
but it breaks down if even a single watch is in place anywhere in the
system. Robin Holt notices that udev is one such culprit - it slows down a
512-thread application on a 512 CPU system from 6 seconds to 22 minutes.
Solve this by adding a flag in the dentry that tells inotify whether or not
its parent inode has a watch on it. Event queueing to parent will skip
taking locks if this flag is cleared. Setting and clearing of this flag on
all child dentries versus event delivery: this is no in terms of race
cases, and that was shown to be equivalent to always performing the check.
The essential behaviour is that activity occuring _after_ a watch has been
added and _before_ it has been removed, will generate events.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Robert Love <rml@novell.com>
Cc: John McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Semaphore to mutex conversion.
The conversion was generated via scripts, and the result was validated
automatically via a script as well.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Semaphore to mutex conversion.
The conversion was generated via scripts, and the result was validated
automatically via a script as well.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: John McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Acked-by: Robert Love <rml@novell.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Fix one-shot support in inotify. We currently drop the IN_ONESHOT flag
during watch addition. Fix is to not do that.
Signed-off-by: Robert Love <rml@novell.com>
Cc: John McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
All standard system calls should be declared in include/linux/syscalls.h.
Add some of the new additions that were previously missed.
Signed-off-by: Arnd Bergmann <arndb@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The below patch lets userspace have more control over the inodes that
inotify will watch. It introduces two new flags.
IN_ONLYDIR -- only watch the inode if it is a directory.
This is needed to avoid the race that can occur when we want to be
sure that we are watching a directory.
IN_DONT_FOLLOW -- don't follow a symlink. In combination
with IN_ONLYDIR we can make sure that we don't watch the target of
symlinks.
The issues the flags fix came up when writing the gnome-vfs inotify
backend. Default behaviour is unchanged.
Signed-off-by: John McCutchan <ttb@tentacle.dhs.org>
Acked-by: Robert Love <rml@novell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Most permission() calls have a struct nameidata * available. This helper
takes that as an argument and thus makes sure we pass it down for lookup
intents and prepares for per-mount read-only support where we need a struct
vfsmount for checking whether a file is writeable.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Fix a bug which was reported and diagnosed by
Stefan Jones <stefan.jones@churchillrandoms.co.uk>
IDR trees include a cache of idr_layer objects. There's no way to destroy
this cache, so when we discard an overall idr tree we end up leaking some
memory.
Add and use idr_destroy() for this. v9fs and infiniband also need to use
idr_destroy() to avoid leaks.
Or, we make the cache global, like radix_tree_preload(). Which is probably
better. Later.
Cc: Eric Van Hensbergen <ericvh@ericvh.myip.org>
Cc: Roland Dreier <rolandd@cisco.com>
Cc: Robert Love <rml@novell.com>
Cc: John McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
People have run into a problem when they do this:
watch (file1, all_events);
watch (file2, some_events);
if file2 is a hard link to file1, some events will be missed because by
default we replace the mask. The patch below adds a flag IN_MASK_ADD which
will cause inotify to add to the existing mask if present.
Signed-off-by: John McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: Robert Love <rml@novell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Bypass an inotify-related fastpath spinlock and several function calls on
systems which have no inotify watches registered.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
There is an off by one problem with idr_get_new_above.
The comment and function name suggest that it will return an id >
starting_id, but it actually returned an id >= starting_id, and kernel
callers other than inotify treated it as such.
The patch below fixes the comment, and fixes inotifys usage. The
function name still doesn't match the behaviour, but it never did.
Signed-off-by: John McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
We are saving the wrong thing in ->last_wd. We want the wd, not the
return value.
Signed-off-by: Robert Love <rml@novell.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
When you rm a watch, an IN_IGNORED event is sent down the event queue
with the watch descriptor that you just rm'd.
If you then add a watch you could get the ignored watch's wd and if you
haven't read the entire event queue, user space will think that it's
newly created watch was just ignored.
To avoid this problem we just use idr_get_new_above instead of
idr_get_new.
Signed-off-by: John McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: Robert Love <rml@novell.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Cc: Robert Love <rml@novell.com>
Cc: John McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Check for (unlikely) errors in the filesystem initialization stuff in
our module_init() function.
Signed-off-by: Robert Love <rml@novell.com>
Signed-off-by: John McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Change default inotify limits: Maximum instances per user to 128 and
maximum events per queue to 16k. The max instances used to be 128; the
change to 8 was a mistake. Memory consumption is fine.
Signed-off-by: Robert Love <rml@novell.com>
Signed-off-by: John McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Handle error out paths better.
Signed-off-by: Robert Love <rml@novell.com>
Signed-off-by: John McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Bug fix: Ensure that the fd passed to inotify_add_watch() and
inotify_rm_watch() belongs to inotify.
Signed-off-by: Robert Love <rml@novell.com>
Signed-off-by: John McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
As an optimization, use fget_light() and fput_light() where possible.
Signed-off-by: Robert Love <rml@novell.com>
Signed-off-by: John McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Miscellaneous invariant clean up, comment fixes, and so on. Trivial
stuff.
Signed-off-by: Robert Love <rml@novell.com>
Signed-off-by: John McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This moves the inotify sysctl knobs to "/proc/sys/fs/inotify" from
"/proc/sys/fs". Also some related cleanup.
Signed-off-by: Robert Love <rml@novell.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
inotify is intended to correct the deficiencies of dnotify, particularly
its inability to scale and its terrible user interface:
* dnotify requires the opening of one fd per each directory
that you intend to watch. This quickly results in too many
open files and pins removable media, preventing unmount.
* dnotify is directory-based. You only learn about changes to
directories. Sure, a change to a file in a directory affects
the directory, but you are then forced to keep a cache of
stat structures.
* dnotify's interface to user-space is awful. Signals?
inotify provides a more usable, simple, powerful solution to file change
notification:
* inotify's interface is a system call that returns a fd, not SIGIO.
You get a single fd, which is select()-able.
* inotify has an event that says "the filesystem that the item
you were watching is on was unmounted."
* inotify can watch directories or files.
Inotify is currently used by Beagle (a desktop search infrastructure),
Gamin (a FAM replacement), and other projects.
See Documentation/filesystems/inotify.txt.
Signed-off-by: Robert Love <rml@novell.com>
Cc: John McCutchan <ttb@tentacle.dhs.org>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
