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>
While developing a 9P server (https://github.com/Barre/ZeroFS) and
testing it under high-load, I was running into allocation failures.
The failures occur even with plenty of free memory available because
kmalloc requires contiguous physical memory.
This results in errors like:
ls: page allocation failure: order:7, mode:0x40c40(GFP_NOFS|__GFP_COMP)
This patch introduces a transport capability flag (supports_vmalloc)
that indicates whether a transport can work with vmalloc'd buffers
(non-physically contiguous memory). Transports requiring DMA should
leave this flag as false.
The fd-based transports (tcp, unix, fd) set this flag to true, and
p9_fcall_init will use kvmalloc instead of kmalloc for these
transports. This allows the allocator to fall back to vmalloc when
contiguous physical memory is not available.
Additionally, if kmem_cache_alloc fails, the code falls back to
kvmalloc for transports that support it.
Signed-off-by: Pierre Barre <pierre@barre.sh>
Reviewed-by: Christian Schoenebeck <linux_oss@crudebyte.com>
Message-ID: <d2017c29-11fb-44a5-bd0f-4204329bbefb@app.fastmail.com>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Add some additional debug flags to assist with debugging
cache changes. Also add some additional open modes so we
can track cache state in fids more directly.
Signed-off-by: Eric Van Hensbergen <ericvh@kernel.org>
Add P9_ERRMAX macro to 9P protocol header which reflects the maximum
error string length of Rerror replies for 9p2000 and 9p2000.u protocol
versions. Unfortunately a maximum error string length is not defined by
the 9p2000 spec, picking 128 as value for now, as this seems to be a
common max. size for POSIX error strings in practice.
9p2000.L protocol version uses Rlerror replies instead which does not
contain an error string.
Link: https://lkml.kernel.org/r/3f23191d21032e7c14852b1e1a4ae26417a36739.1657920926.git.linux_oss@crudebyte.com
Signed-off-by: Christian Schoenebeck <linux_oss@crudebyte.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>
Now that all transports are split into modules it may happen that no
transports are registered when v9fs_get_default_trans() is called.
When that is the case try to load more transports from modules.
Link: https://lkml.kernel.org/r/20211103193823.111007-5-linux@weissschuh.net
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
[Dominique: constify v9fs_get_trans_by_name argument as per patch1v2]
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>
Kit Dallege
Eric Sandeen
Dominique Martinet
Pierre Barre
David Howells
Eric Van Hensbergen
Christian Schoenebeck
Kent Overstreet
Thomas Weißschuh
Jianyong Wu
Greg Kurz
Randy Dunlap
Dominique Martinet