Let's raise the default msize value to 128k.
The 'msize' option defines the maximum message size allowed for any
message being transmitted (in both directions) between 9p server and 9p
client during a 9p session.
Currently the default 'msize' is just 8k, which is way too conservative.
Such a small 'msize' value has quite a negative performance impact,
because individual 9p messages have to be split up far too often into
numerous smaller messages to fit into this message size limitation.
A default value of just 8k also has a much higher probablity of hitting
short-read issues like: https://gitlab.com/qemu-project/qemu/-/issues/409
Unfortunately user feedback showed that many 9p users are not aware that
this option even exists, nor the negative impact it might have if it is
too low.
Link: http://lkml.kernel.org/r/61ea0f0faaaaf26dd3c762eabe4420306ced21b9.1630770829.git.linux_oss@crudebyte.com
Link: https://lists.gnu.org/archive/html/qemu-devel/2021-03/msg01003.html
Signed-off-by: Christian Schoenebeck <linux_oss@crudebyte.com>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Historically TCP has been limited to 64K buffers, but increasing
msize provides huge performance benefits especially as latency
increase so allow for bigger buffers.
Ideally further improvements could change the allocation from the
current contiguous chunk in slab (kmem_cache) to some scatter-gather
compatible API...
Note this only increases the max possible setting, not the default
value.
Link: http://lkml.kernel.org/r/YTQB5jCbvhmCWzNd@codewreck.org
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Fix the following W=1 kernel build warning(s):
net/9p/client.c:133: warning: expecting prototype for parse_options(). Prototype was for parse_opts() instead
net/9p/client.c:269: warning: expecting prototype for p9_req_alloc(). Prototype was for p9_tag_alloc() instead
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Fix the following W=1 kernel build warning(s):
net/9p/trans_fd.c:881: warning: expecting prototype for p9_mux_destroy(). Prototype was for p9_conn_destroy() instead
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Fix the following W=1 kernel build warning(s):
net/9p/error.c:207: warning: expecting prototype for errstr2errno(). Prototype was for p9_errstr2errno() instead
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull 9p update from Dominique Martinet:
- fix long-standing limitation on open-unlink-fop pattern
- add refcount to p9_fid (fixes the above and will allow for more
cleanups and simplifications in the future)
* tag '9p-for-5.11-rc1' of git://github.com/martinetd/linux:
9p: Remove unnecessary IS_ERR() check
9p: Uninitialized variable in v9fs_writeback_fid()
9p: Fix writeback fid incorrectly being attached to dentry
9p: apply review requests for fid refcounting
9p: add refcount to p9_fid struct
fs/9p: search open fids first
fs/9p: track open fids
fs/9p: fix create-unlink-getattr idiom
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>
Fixes several outstanding bug reports of not being able to getattr from an
open file after an unlink. This patch cleans up transient fids on an unlink
and will search open fids on a client if it detects a dentry that appears to
have been unlinked. This search is necessary because fstat does not pass fd
information through the VFS API to the filesystem, only the dentry which for
9p has an imperfect match to fids.
Inherent in this patch is also a fix for the qid handling on create/open
which apparently wasn't being set correctly and was necessary for the search
to succeed.
A possible optimization over this fix is to include accounting of open fids
with the inode in the private data (in a similar fashion to the way we track
transient fids with dentries). This would allow a much quicker search for
a matching open fid.
(changed v9fs_fid_find_global to v9fs_fid_find_inode in comment)
Link: http://lkml.kernel.org/r/20200923141146.90046-2-jianyong.wu@arm.com
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Signed-off-by: Jianyong Wu <jianyong.wu@arm.com>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
net/9p/client.c:420: warning: Function parameter or member 'c' not described in 'p9_client_cb'
net/9p/client.c:420: warning: Function parameter or member 'req' not described in 'p9_client_cb'
net/9p/client.c:420: warning: Function parameter or member 'status' not described in 'p9_client_cb'
net/9p/client.c:568: warning: Function parameter or member 'uidata' not described in 'p9_check_zc_errors'
net/9p/trans_common.c:23: warning: Function parameter or member 'nr_pages' not described in 'p9_release_pages'
net/9p/trans_common.c:23: warning: Function parameter or member 'pages' not described in 'p9_release_pages'
net/9p/trans_fd.c:132: warning: Function parameter or member 'rreq' not described in 'p9_conn'
net/9p/trans_fd.c:132: warning: Function parameter or member 'wreq' not described in 'p9_conn'
net/9p/trans_fd.c:56: warning: Function parameter or member 'privport' not described in 'p9_fd_opts'
net/9p/trans_rdma.c:113: warning: Function parameter or member 'cqe' not described in 'p9_rdma_context'
net/9p/trans_rdma.c:129: warning: Function parameter or member 'privport' not described in 'p9_rdma_opts'
net/9p/trans_virtio.c:215: warning: Function parameter or member 'limit' not described in 'pack_sg_list_p'
net/9p/trans_virtio.c:83: warning: Function parameter or member 'chan_list' not described in 'virtio_chan'
net/9p/trans_virtio.c:83: warning: Function parameter or member 'p9_max_pages' not described in 'virtio_chan'
net/9p/trans_virtio.c:83: warning: Function parameter or member 'ring_bufs_avail' not described in 'virtio_chan'
net/9p/trans_virtio.c:83: warning: Function parameter or member 'tag' not described in 'virtio_chan'
net/9p/trans_virtio.c:83: warning: Function parameter or member 'vc_wq' not described in 'virtio_chan'
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Dominique Martinet <asmadeus@codewreck.org>
Link: https://lore.kernel.org/r/20201031182655.1082065-1-andrew@lunn.ch
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Pull 9p updates from Dominique Martinet:
- some code cleanup
- a couple of static analysis fixes
- setattr: try to pick a fid associated with the file rather than the
dentry, which might sometimes matter
* tag '9p-for-5.9-rc1' of git://github.com/martinetd/linux:
9p: Remove unneeded cast from memory allocation
9p: remove unused code in 9p
net/9p: Fix sparse endian warning in trans_fd.c
9p: Fix memory leak in v9fs_mount
9p: retrieve fid from file when file instance exist.
