tree 2db5e37737da91f1b2b32136e4e10ad540d8dc09
parent ce1d5a491f0ee50560416a73faa5e4ddbab074bd
author Miklos Szeredi <miklos@szeredi.hu> 1144734899 -0700
committer Linus Torvalds <torvalds@g5.osdl.org> 1144761529 -0700

[PATCH] fuse: account background requests

The previous patch removed limiting the number of outstanding requests.  This
patch adds a much simpler limiting, that is also compatible with file locking
operations.

A task may have at most one synchronous request allocated.  So these requests
need not be otherwise limited.

However the number of background requests (release, forget, asynchronous
reads, interrupted requests) can grow indefinitely.  This can be used by a
malicous user to cause FUSE to allocate arbitrary amounts of unswappable
kernel memory, denying service.

For this reason add a limit for the number of background requests, and block
allocations of new requests until the number goes bellow the limit.

Also use this mechanism to block all requests until the INIT reply is
received.

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>