Convert 9p to the new mount API. This patch consolidates all parsing
into fs/9p/v9fs.c, which stores all results into a filesystem context
which can be passed to the various transports as needed.
Some of the parsing helper functions such as get_cache_mode() have been
eliminated in favor of using the new mount API's enum param type,
for simplicity.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Message-ID: <20251010214222.1347785-5-sandeen@redhat.com>
[ Dominique: handled source explicitly as per follow-up discussion ]
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
This patch creates a new v9fs_context structure which includes
new p9_session_opts and p9_client_opts structures, as well as
re-using the existing p9_fd_opts and p9_rdma_opts to store options
during parsing. The new structure will be used in the next
commit to pass all parsed options to the appropriate transports.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Message-ID: <20251010214222.1347785-4-sandeen@redhat.com>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
With the new mount API all option parsing will need to happen
in fs/v9fs.c, so move some existing data structures and macros
to header files to facilitate this. Rename some to reflect
the transport they are used for (rdma, fd, etc), for clarity.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Message-ID: <20251010214222.1347785-3-sandeen@redhat.com>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
This adds a tracepoint event for 9p fid lifecycle tracing: when a fid
is created, its reference count increased/decreased, and freed.
The new 9p_fid_ref tracepoint should help anyone wishing to debug any
fid problem such as missing clunk (destroy) or use-after-free.
Link: https://lkml.kernel.org/r/20220612085330.1451496-6-asmadeus@codewreck.org
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Fix race issue in fid contention.
Eric's and Greg's patch offer a mechanism to fix open-unlink-f*syscall
bug in 9p. But there is race issue in fid parallel accesses.
As Greg's patch stores all of fids from opened files into according inode,
so all the lookup fid ops can retrieve fid from inode preferentially. But
there is no mechanism to handle the fid contention issue. For example,
there are two threads get the same fid in the same time and one of them
clunk the fid before the other thread ready to discard the fid. In this
scenario, it will lead to some fatal problems, even kernel core dump.
I introduce a mechanism to fix this race issue. A counter field introduced
into p9_fid struct to store the reference counter to the fid. When a fid
is allocated from the inode or dentry, the counter will increase, and
will decrease at the end of its occupation. It is guaranteed that the
fid won't be clunked before the reference counter go down to 0, then
we can avoid the clunked fid to be used.
tests:
race issue test from the old test case:
for file in {01..50}; do touch f.${file}; done
seq 1 1000 | xargs -n 1 -P 50 -I{} cat f.* > /dev/null
open-unlink-f*syscall test:
I have tested for f*syscall include: ftruncate fstat fchown fchmod faccessat.
Link: http://lkml.kernel.org/r/20200923141146.90046-5-jianyong.wu@arm.com
Fixes: 478ba09edc ("fs/9p: search open fids first")
Signed-off-by: Jianyong Wu <jianyong.wu@arm.com>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
A user doesn't necessarily want to wait for all the requested data to
be available, since the waiting time for each request is unbounded.
The new method permits sending one read request at a time and getting
the response ASAP, allowing to use 9pnet with synthetic file systems
representing arbitrary data streams.
Link: http://lkml.kernel.org/r/20200205204053.12751-1-l29ah@cock.li
Signed-off-by: Sergey Alirzaev <l29ah@cock.li>
Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation this program is
distributed in the hope that it will be useful but without any
warranty without even the implied warranty of merchantability or
fitness for a particular purpose see the gnu general public license
for more details you should have received a copy of the gnu general
public license along with this program if not write to free software
foundation 51 franklin street fifth floor boston ma 02111 1301 usa
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 27 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Steve Winslow <swinslow@gmail.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190528170026.981318839@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To avoid use-after-free(s), use a refcount to keep track of the
usable references to any instantiated struct p9_req_t.
This commit adds p9_req_put(), p9_req_get() and p9_req_try_get() as
wrappers to kref_put(), kref_get() and kref_get_unless_zero().
These are used by the client and the transports to keep track of
valid requests' references.
p9_free_req() is added back and used as callback by kref_put().
Add SLAB_TYPESAFE_BY_RCU as it ensures that the memory freed by
kmem_cache_free() will not be reused for another type until the rcu
synchronisation period is over, so an address gotten under rcu read
lock is safe to inc_ref() without corrupting random memory while
the lock is held.
Link: http://lkml.kernel.org/r/1535626341-20693-1-git-send-email-asmadeus@codewreck.org
Co-developed-by: Dominique Martinet <dominique.martinet@cea.fr>
Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com>
Reported-by: syzbot+467050c1ce275af2a5b8@syzkaller.appspotmail.com
Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>
Having a specific cache for the fcall allocations helps speed up
end-to-end latency.
The caches will automatically be merged if there are multiple caches
of items with the same size so we do not need to try to share a cache
between different clients of the same size.
Since the msize is negotiated with the server, only allocate the cache
after that negotiation has happened - previous allocations or
allocations of different sizes (e.g. zero-copy fcall) are made with
kmalloc directly.
Some figures on two beefy VMs with Connect-IB (sriov) / trans=rdma,
with ior running 32 processes in parallel doing small 32 bytes IOs:
- no alloc (4.18-rc7 request cache): 65.4k req/s
- non-power of two alloc, no patch: 61.6k req/s
- power of two alloc, no patch: 62.2k req/s
- non-power of two alloc, with patch: 64.7k req/s
- power of two alloc, with patch: 65.1k req/s
Link: http://lkml.kernel.org/r/1532943263-24378-2-git-send-email-asmadeus@codewreck.org
Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>
Acked-by: Jun Piao <piaojun@huawei.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Greg Kurz <groug@kaod.org>
Eric Sandeen
David Howells
Kent Overstreet
Dominique Martinet
Jianyong Wu
Greg Kurz
Dominique Martinet
Sergey Alirzaev
Thomas Gleixner
Tomas Bortoli
Matthew Wilcox
Al Viro