Subject: [PATCH] nfs: remove superfluous BUG_ON()s
Remove duplicated BUG_ON()s from nfs[4]_create_server()
(we make the same checks earlier in both functions).
This takes care of the following entries from Dan's list:
fs/nfs/client.c +1078 nfs_create_server(47) warning: variable derefenced before check 'server->nfs_client'
fs/nfs/client.c +1079 nfs_create_server(48) warning: variable derefenced before check 'server->nfs_client->rpc_ops'
fs/nfs/client.c +1363 nfs4_create_server(43) warning: variable derefenced before check 'server->nfs_client'
fs/nfs/client.c +1364 nfs4_create_server(44) warning: variable derefenced before check 'server->nfs_
Reported-by: Dan Carpenter <error27@gmail.com>
Cc: corbet@lwn.net
Cc: eteo@redhat.com
Cc: Julia Lawall <julia@diku.dk>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Hi.
I have a proposal for possibly resolving this issue.
I believe that this situation occurs due to the way that the
Linux NFS client handles writes which modify partial pages.
The Linux NFS client handles partial page modifications by
allocating a page from the page cache, copying the data from
the user level into the page, and then keeping track of the
offset and length of the modified portions of the page. The
page is not marked as up to date because there are portions
of the page which do not contain valid file contents.
When a read call comes in for a portion of the page, the
contents of the page must be read in the from the server.
However, since the page may already contain some modified
data, that modified data must be written to the server
before the file contents can be read back in the from server.
And, since the writing and reading can not be done atomically,
the data must be written and committed to stable storage on
the server for safety purposes. This means either a
FILE_SYNC WRITE or a UNSTABLE WRITE followed by a COMMIT.
This has been discussed at length previously.
This algorithm could be described as modify-write-read. It
is most efficient when the application only updates pages
and does not read them.
My proposed solution is to add a heuristic to decide whether
to do this modify-write-read algorithm or switch to a read-
modify-write algorithm when initially allocating the page
in the write system call path. The heuristic uses the modes
that the file was opened with, the offset in the page to
read from, and the size of the region to read.
If the file was opened for reading in addition to writing
and the page would not be filled completely with data from
the user level, then read in the old contents of the page
and mark it as Uptodate before copying in the new data. If
the page would be completely filled with data from the user
level, then there would be no reason to read in the old
contents because they would just be copied over.
This would optimize for applications which randomly access
and update portions of files. The linkage editor for the
C compiler is an example of such a thing.
I tested the attached patch by using rpmbuild to build the
current Fedora rawhide kernel. The kernel without the
patch generated about 269,500 WRITE requests. The modified
kernel containing the patch generated about 261,000 WRITE
requests. Thus, about 8,500 fewer WRITE requests were
generated. I suspect that many of these additional
WRITE requests were probably FILE_SYNC requests to WRITE
a single page, but I didn't test this theory.
The difference between this patch and the previous one was
to remove the unneeded PageDirty() test. I then retested to
ensure that the resulting system continued to behave as
desired.
Thanx...
ps
Signed-off-by: Peter Staubach <staubach@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
For events that are rare, such as referral DNS lookups, it makes limited
sense to have a daemon constantly listening for upcalls on a channel. An
alternative in those cases might simply be to run the app that fills the
cache using call_usermodehelper_exec() and friends.
The following patch allows the cache_detail to specify alternative upcall
mechanisms for these particular cases.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
While we do want to protect against multiple concurrent readers and writers
on each upcall/downcall pipe, we don't want to limit concurrent reading and
writing to separate caches.
This patch therefore replaces the static buffer 'write_buf', which can only
be used by one writer at a time, with use of the page cache as the
temporary buffer for downcalls. We still fall back to using the the old
global buffer if the downcall is larger than PAGE_CACHE_SIZE, since this is
apparently needed by the SPKM security context initialisation.
It then replaces the use of the global 'queue_io_mutex' with the
inode->i_mutex in cache_read() and cache_write().
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Also ensure that we destroy those files before we destroy the cache_detail.
Otherwise, user processes might attempt to write into uninitialised caches.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
In order to allow rpc_pipefs to create directories with different types of
subtrees, it is useful to allow the caller to customise the subtree filling
process.
In order to do so, we separate out the parts which are specific to making
an RPC client directory, and put them in a separate helper, then we convert
the process of filling the directory contents into a callback.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
There is still a little wart or two there: Since we've already got a
vfsmount, we might as well pass that in to rpc_create_client_dir.
Another point is that if we open code __rpc_lookup_path() here, then we can
avoid looking up the entire parent directory path over and over again: it
doesn't change.
Also get rid of rpc_clnt->cl_pathname, since it has no users...
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This reflects the fact that rpc_mkdir() as it stands today, can only create
a RPC client type directory.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Clean up: provide documenting comments for the functions in
net/sunrpc/timer.c.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
After a bind completes, update the transport instance's address
strings so debugging messages display the current port the transport
is connected to.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
At some point, I recall that rpc_pipe_fs used RPC_DISPLAY_ALL.
Currently there are no uses of RPC_DISPLAY_ALL outside the transport
modules themselves, so we can safely get rid of it.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Clean up: Give the "addr" and "port" field less ambiguous names.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Clean up: Replace PROC macro with open coded C99 structure
initializers to improve readability.
The rpcbind v4 GETVERSADDR procedure is never sent by the current
implementation, so it is not copied to the new structures.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Replace the open-coded decode logic for PMAP_GETPORT/RPCB_GETADDR with
an xdr_stream-based implementation, similar to what NFSv4 uses, to
protect against buffer overflows. The new implementation also checks
that the incoming port number is reasonable.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Replace the open-coded decode logic for rpcbind UNSET results with an
xdr_stream-based implementation, similar to what NFSv4 uses, to
protect against buffer overflows.
The new function is unused for the moment.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Replace the open-coded encode logic for rpcbind arguments with an
xdr_stream-based implementation, similar to what NFSv4 uses, to
better protect against buffer overflows.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
In write_failover_ip(), replace the sscanf() with a call to the common
sunrpc.ko presentation address parser.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Clean up: Use shared rpc_set_port() function instead of nlm_clear_port().
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Clean up: Use the common routine now provided in sunrpc.ko for parsing mount
addresses.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Clean up: In addition to using the new generic rpc_ntop() and
rpc_get_port() functions, have the RPC client compute the presentation
address buffer sizes dynamically using kstrdup().
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
RPC universal address generation is currently done in several places:
rpcb_clnt.c, nfs4proc.c xprtsock.c, and xprtrdma.c. Remove the
redundant cases that convert a socket address to a universal
address. The nfs4proc.c case takes a pre-formatted presentation
address string, not a socket address, so we'll leave that one.
Because the new uaddr constructor uses the recently introduced
rpc_ntop(), it now supports proper "::" shorthanding for IPv6
addresses. This allows the kernel to register properly formed
universal addresses with the local rpcbind service, in _all_ cases.
The kernel can now also send properly formed universal addresses in
RPCB_GETADDR requests, and support link-local properly when
encoding and decoding IPv6 addresses.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Introduce a set of functions in the kernel's RPC implementation for
converting between a socket address and either a standard
presentation address string or an RPC universal address.
The universal address functions will be used to encode and decode
RPCB_FOO and NFSv4 SETCLIENTID arguments. The other functions are
part of a previous promise to deliver shared functions that can be
used by upper-layer protocols to display and manipulate IP
addresses.
The kernel's current address printf formatters were designed
specifically for kernel to user-space APIs that require a particular
string format for socket addresses, thus are somewhat limited for the
purposes of sunrpc.ko. The formatter for IPv6 addresses, %pI6, does
not support short-handing or scope IDs. Also, these printf formatters
are unique per address family, so a separate formatter string is
required for printing AF_INET and AF_INET6 addresses.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Clean up: To make subsequent patches cleaner, move the XDR data type
size macros to the top of the file (similar to nfs4xdr.c) first.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Clean up: Replace the single-integer definition of RPCBIND_MAXUADDRLEN
with a definition that is based on previously defined address string
sizes, and document the way this maximum is calculated. Also provide
a separate macro for the size of the port number extension.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Commit a14017db added support in the kernel's NFS mount client to
decode the authentication flavor list returned by mountd.
The NFS client can now use this list to determine whether the
authentication flavor requested by the user is actually supported
by the server.
Note we don't actually negotiate the security flavor if none was
specified by the user. Instead, we try to use AUTH_SYS, and fail if
the server does not support it. This prevents us from negotiating
an inappropriate security flavor (some servers list AUTH_NULL first).
If the server does not support AUTH_SYS, the user must provide an
appropriate security flavor by specifying the "sec=" mount option.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Previous logic in the NFS mount parsing code path assumed
auth_flavor_len was set to zero for simple authentication flavors
(like AUTH_UNIX), and 1 for compound flavors (like AUTH_GSS).
At some earlier point (maybe even before the option parsers were
merged?) specific checks for auth_flavor_len being zero were removed
from the functions that validate the mount option that sets the mount
point's authentication flavor.
Since we are populating an array for authentication flavors, the
auth_flavor_len should always be set to the number of flavors. Let's
eliminate some cleverness here, and prepare for new logic that needs
to know the number of flavors in the auth_flavors[] array.
(auth_flavors[] is an array because at some point we want to allow a
list of acceptable authentication flavors to be specified via the sec=
mount option. For now it remains a single element array).
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
After certain failure modes of an NFS mount, an NFS client should send
a MOUNTPROC_UMNT request to remove the just-added mount entry from the
server's mount table. While no-one should rely on the accuracy of the
server's mount table, sending a UMNT is simply being a good internet
neighbor.
Since NFS mount processing is handled in the kernel now, we will need
a function in the kernel's mountd client that can post a MOUNTRPC_UMNT
request, in order to handle these failure modes.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
The new minorversion= mount option (commit 3fd5be9e) was merged at
the same time as the recent sloppy parser fixes (commit a5a16bae),
so minorversion= still uses the old value parsing logic.
If the minorversion= option specifies a bogus value, it should fail
with "bad value" not "bad option."
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Tighten up the validity checking in param_set_port: check for NULL pointers.
Ensure that the option shows up on 'modinfo' output.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Parameters like the minimum reserved port, and the number of slot entries
should really be module parameters rather than sysctls.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
