linux.git/fs/notify/notification.c, branch v2.6.35

inotify: fix coalesce duplicate events into a single event in special case

2009-10-18T19:49:38+00:00

If we do rename a dir entry, like this:

  rename("/tmp/ino7UrgoJ.rename1", "/tmp/ino7UrgoJ.rename2")
  rename("/tmp/ino7UrgoJ.rename2", "/tmp/ino7UrgoJ")

The duplicate events should be coalesced into a single event. But those two
events do not be coalesced into a single event, due to some bad check in
event_compare(). It can not match the two NULL inodes as the same event.

Signed-off-by: Wei Yongjun 
Signed-off-by: Eric Paris

inotify: tail drop inotify q_overflow events

2009-08-17T20:37:37+00:00

In f44aebcc the tail drop logic of events with no file backing
(q_overflow and in_ignored) was reversed so IN_IGNORED events would
never be tail dropped.  This now means that Q_OVERFLOW events are NOT
tail dropped.  The fix is to not tail drop IN_IGNORED, but to tail drop
Q_OVERFLOW.

Signed-off-by: Eric Paris 
Signed-off-by: Linus Torvalds

notify: unused event private race

2009-08-17T20:37:37+00:00

inotify decides if private data it passed to get added to an event was
used by checking list_empty().  But it's possible that the event may
have been dequeued and the private event removed so it would look empty.

The fix is to use the return code from fsnotify_add_notify_event rather
than looking at the list.

Signed-off-by: Eric Paris 
Signed-off-by: Linus Torvalds

inotify: use GFP_NOFS under potential memory pressure

2009-07-21T19:26:27+00:00

inotify can have a watchs removed under filesystem reclaim.

=================================
[ INFO: inconsistent lock state ]
2.6.31-rc2 #16
---------------------------------
inconsistent {IN-RECLAIM_FS-W} -> {RECLAIM_FS-ON-W} usage.
khubd/217 [HC0[0]:SC0[0]:HE1:SE1] takes:
 (iprune_mutex){+.+.?.}, at: [] invalidate_inodes+0x20/0xe3
{IN-RECLAIM_FS-W} state was registered at:
  [] __lock_acquire+0x2c9/0xac4
  [] lock_acquire+0x9f/0xc2
  [] __mutex_lock_common+0x2d/0x323
  [] mutex_lock_nested+0x2e/0x36
  [] shrink_icache_memory+0x38/0x1b2
  [] shrink_slab+0xe2/0x13c
  [] kswapd+0x3d1/0x55d
  [] kthread+0x66/0x6b
  [] kernel_thread_helper+0x7/0x10
  [] 0xffffffff

Two things are needed to fix this.  First we need a method to tell
fsnotify_create_event() to use GFP_NOFS and second we need to stop using
one global IN_IGNORED event and allocate them one at a time.  This solves
current issues with multiple IN_IGNORED on a queue having tail drop
problems and simplifies the allocations since we don't have to worry about
two tasks opperating on the IGNORED event concurrently.

Signed-off-by: Eric Paris

fsnotify: fix inotify tail drop check with path entries

2009-07-21T19:26:26+00:00

fsnotify drops new events when they are the same as the tail event on the
queue to be sent to userspace.  The problem is that if the event comes with
a path we forget to break out of the switch statement and fall into the
code path which matches on events that do not have any type of file backed
information (things like IN_UNMOUNT and IN_Q_OVERFLOW).  The problem is
that this code thinks all such events should be dropped.  Fix is to add a
break.

Signed-off-by: Eric Paris

inotify: check filename before dropping repeat events

2009-07-21T19:26:26+00:00

inotify drops events if the last event on the queue is the same as the
current event.  But it does 2 things wrong.  First it is comparing old->inode
with new->inode.  But after an event if put on the queue the ->inode is no
longer allowed to be used.  It's possible between the last event and this new
event the inode could be reused and we would falsely match the inode's memory
address between two differing events.

The second problem is that when a file is removed fsnotify is passed the
negative dentry for the removed object rather than the postive dentry from
immediately before the removal.  This mean the (broken) inotify tail drop code
was matching the NULL ->inode of differing events.

The fix is to check the file name which is stored with events when doing the
tail drop instead of wrongly checking the address of the stored ->inode.

Reported-by: Scott James Remnant 
Signed-off-by: Eric Paris

fsnotify: allow groups to add private data to events

2009-06-11T18:57:54+00:00

inotify needs per group information attached to events.  This patch allows
groups to attach private information and implements a callback so that
information can be freed when an event is being destroyed.

Signed-off-by: Eric Paris 
Acked-by: Al Viro 
Cc: Christoph Hellwig

fsnotify: add correlations between events

2009-06-11T18:57:54+00:00

As part of the standard inotify events it includes a correlation cookie
between two dentry move operations.  This patch includes the same behaviour
in fsnotify events.  It is needed so that inotify userspace can be
implemented on top of fsnotify.

Signed-off-by: Eric Paris 
Acked-by: Al Viro 
Cc: Christoph Hellwig

fsnotify: include pathnames with entries when possible

2009-06-11T18:57:53+00:00

When inotify wants to send events to a directory about a child it includes
the name of the original file.  This patch collects that filename and makes
it available for notification.

Signed-off-by: Eric Paris 
Acked-by: Al Viro 
Cc: Christoph Hellwig

fsnotify: generic notification queue and waitq

2009-06-11T18:57:53+00:00

inotify needs to do asyc notification in which event information is stored
on a queue until the listener is ready to receive it.  This patch
implements a generic notification queue for inotify (and later fanotify) to
store events to be sent at a later time.

Signed-off-by: Eric Paris 
Acked-by: Al Viro 
Cc: Christoph Hellwig