The main point of the guarded SETATTR is to prevent races with other
WRITE and SETATTR calls. That requires that the check of the guard time
against the inode ctime be done after taking the inode lock.
Furthermore, we need to take into account the 32-bit nature of
timestamps in NFSv3, and the possibility that files may change at a
faster rate than once a second.
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
xdr_stream_subsegment() already returns a boolean value.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Replace the check for buffer over/underflow with a helper that is
commonly used for this purpose. The helper also sets xdr->nwords
correctly after successfully linearizing the symlink argument into
the stream's scratch buffer.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
NFS_OFFSET_MAX was introduced way back in Linux v2.3.y before there
was a kernel-wide OFFSET_MAX value. As a clean up, replace the last
few uses of it with its generic equivalent, and get rid of it.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
iattr::ia_size is a loff_t, so these NFSv3 procedures must be
careful to deal with incoming client size values that are larger
than s64_max without corrupting the value.
Silently capping the value results in storing a different value
than the client passed in which is unexpected behavior, so remove
the min_t() check in decode_sattr3().
Note that RFC 1813 permits only the WRITE procedure to return
NFS3ERR_FBIG. We believe that NFSv3 reference implementations
also return NFS3ERR_FBIG when ia_size is too large.
Cc: stable@vger.kernel.org
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
These functions are related to file handle processing and have
nothing to do with XDR encoding or decoding. Also they are no longer
NFSv3-specific. As a clean-up, move their definitions to a more
appropriate location. WCC is also an NFSv3-specific term, so rename
them as general-purpose helpers.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
On the wire, I observed NFSv4 OPEN(CREATE) operations sometimes
returning a reasonable-looking value in the cinfo.before field and
zero in the cinfo.after field.
RFC 8881 Section 10.8.1 says:
> When a client is making changes to a given directory, it needs to
> determine whether there have been changes made to the directory by
> other clients. It does this by using the change attribute as
> reported before and after the directory operation in the associated
> change_info4 value returned for the operation.
and
> ... The post-operation change
> value needs to be saved as the basis for future change_info4
> comparisons.
A good quality client implementation therefore saves the zero
cinfo.after value. During a subsequent OPEN operation, it will
receive a different non-zero value in the cinfo.before field for
that directory, and it will incorrectly believe the directory has
changed, triggering an undesirable directory cache invalidation.
There are filesystem types where fs_supports_change_attribute()
returns false, tmpfs being one. On NFSv4 mounts, this means the
fh_getattr() call site in fill_pre_wcc() and fill_post_wcc() is
never invoked. Subsequently, nfsd4_change_attribute() is invoked
with an uninitialized @stat argument.
In fill_pre_wcc(), @stat contains stale stack garbage, which is
then placed on the wire. In fill_post_wcc(), ->fh_post_wc is all
zeroes, so zero is placed on the wire. Both of these values are
meaningless.
This fix can be applied immediately to stable kernels. Once there
are more regression tests in this area, this optimization can be
attempted again.
Fixes: 428a23d2bf ("nfsd: skip some unnecessary stats in the v4 case")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Returning an undecorated integer is an age-old trope, but it's
not clear (even to previous experts in this code) that the only
valid return values are 1 and 0. These functions do not return
a negative errno, rpc_stat value, or a positive length.
Document there are only two valid return values by having
.pc_encode return only true or false.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
The passed-in value of the "__be32 *p" parameter is now unused in
every server-side XDR encoder, and can be removed.
Note also that there is a line in each encoder that sets up a local
pointer to a struct xdr_stream. Passing that pointer from the
dispatcher instead saves one line per encoder function.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Returning an undecorated integer is an age-old trope, but it's
not clear (even to previous experts in this code) that the only
valid return values are 1 and 0. These functions do not return
a negative errno, rpc_stat value, or a positive length.
Document there are only two valid return values by having
.pc_decode return only true or false.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
The passed-in value of the "__be32 *p" parameter is now unused in
every server-side XDR decoder, and can be removed.
Note also that there is a line in each decoder that sets up a local
pointer to a struct xdr_stream. Passing that pointer from the
dispatcher instead saves one line per decoder function.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Refactor.
Now that the NFSv2 and NFSv3 XDR decoders have been converted to
use xdr_streams, the WRITE decoder functions can use
xdr_stream_subsegment() to extract the WRITE payload into its own
xdr_buf, just as the NFSv4 WRITE XDR decoder currently does.
That makes it possible to pass the first kvec, pages array + length,
page_base, and total payload length via a single function parameter.
The payload's page_base is not yet assigned or used, but will be in
subsequent patches.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Most of the fields in 'struct knfsd_fh' are 2 levels deep (a union and a
struct) and are accessed using macros like:
#define fh_FOO fh_base.fh_new.fb_FOO
This patch makes the union and struct anonymous, so that "fh_FOO" can be
a name directly within 'struct knfsd_fh' and the #defines aren't needed.
The file handle as a whole is sometimes accessed as "fh_base" or
"fh_base.fh_pad", neither of which are particularly helpful names.
As the struct holding the filehandle is now anonymous, we
cannot use the name of that, so we union it with 'fh_raw' and use that
where the raw filehandle is needed. fh_raw also ensure the structure is
large enough for the largest possible filehandle.
fh_raw is a 'char' array, removing any need to cast it for memcpy etc.
SVCFH_fmt() is simplified using the "%ph" printk format. This
changes the appearance of filehandles in dprintk() debugging, making
them a little more precise.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
The benefit of the xdr_stream helpers is that they transparently
handle encoding an XDR data item that crosses page boundaries.
Most of the open-coded logic to do that here can be eliminated.
A sub-buffer and sub-stream are set up as a sink buffer for the
directory entry encoder. As an entry is encoded, it is added to
the end of the content in this buffer/stream. The total length of
the directory list is tracked in the buffer's @len field.
When it comes time to encode the Reply, the sub-buffer is merged
into rq_res's page array at the correct place using
xdr_write_pages().
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Clean up: Counting the bytes used by each returned directory entry
seems less brittle to me than trying to measure consumed pages after
the fact.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Refactor: De-duplicate identical code that handles encoding of
directory offset cookies across page boundaries.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Also, clean up: Rename the encoder function to match the name of
the result structure in RFC 1813, consistent with other encoder
function names in nfs3xdr.c. "diropres" is an NFSv2 thingie.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
As an additional clean up, some renaming is done to more closely
reflect the data type and variable names used in the NFSv3 XDR
definition provided in RFC 1813. "attrstat" is an NFSv2 thingie.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
In the typical case of v4 and an i_version-supporting filesystem, we can
skip a stat which is only required to fake up a change attribute from
ctime.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit removes the last usage of the original decode_sattr3(),
so it is removed as a clean-up.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Similar to the WRITE decoder, code that checks the sanity of the
payload size is re-wired to work with xdr_stream infrastructure.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
As an additional clean up, neither nfsd3_proc_readdir() nor
nfsd3_proc_readdirplus() make use of the dircount argument, so
remove it from struct nfsd3_readdirargs.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
De-duplicate some code that is used by both READDIR and READDIRPLUS
to build the dirlist in the Reply. Because this code is not related
to decoding READ arguments, it is moved to a more appropriate spot.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Trond Myklebust