diff options
authorJeff Layton <jlayton@redhat.com>2007-05-09 02:34:50 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-05-09 12:30:54 -0700
commitcd123012d99fde4759500fee611e724e4f3016e3 (patch)
parent669716433598a1498049e75a84a5aaf69c8da173 (diff)
RPC: add wrapper for svc_reserve to account for checksum
When the kernel calls svc_reserve to downsize the expected size of an RPC reply, it fails to account for the possibility of a checksum at the end of the packet. If a client mounts a NFSv2/3 with sec=krb5i/p, and does I/O then you'll generally see messages similar to this in the server's ring buffer: RPC request reserved 164 but used 208 While I was never able to verify it, I suspect that this problem is also the root cause of some oopses I've seen under these conditions: https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=227726 This is probably also a problem for other sec= types and for NFSv4. The large reserved size for NFSv4 compound packets seems to generally paper over the problem, however. This patch adds a wrapper for svc_reserve that accounts for the possibility of a checksum. It also fixes up the appropriate callers of svc_reserve to call the wrapper. For now, it just uses a hardcoded value that I determined via testing. That value may need to be revised upward as things change, or we may want to eventually add a new auth_op that attempts to calculate this somehow. Unfortunately, there doesn't seem to be a good way to reliably determine the expected checksum length prior to actually calculating it, particularly with schemes like spkm3. Signed-off-by: Jeff Layton <jlayton@redhat.com> Acked-by: Neil Brown <neilb@suse.de> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Acked-by: J. Bruce Fields <bfields@citi.umich.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
4 files changed, 22 insertions, 3 deletions
diff --git a/fs/nfsd/nfs3proc.c b/fs/nfsd/nfs3proc.c
index 7f5bad0393b..eac82830bfd 100644
--- a/fs/nfsd/nfs3proc.c
+++ b/fs/nfsd/nfs3proc.c
@@ -177,7 +177,7 @@ nfsd3_proc_read(struct svc_rqst *rqstp, struct nfsd3_readargs *argp,
if (max_blocksize < resp->count)
resp->count = max_blocksize;
- svc_reserve(rqstp, ((1 + NFS3_POST_OP_ATTR_WORDS + 3)<<2) + resp->count +4);
+ svc_reserve_auth(rqstp, ((1 + NFS3_POST_OP_ATTR_WORDS + 3)<<2) + resp->count +4);
fh_copy(&resp->fh, &argp->fh);
nfserr = nfsd_read(rqstp, &resp->fh, NULL,
diff --git a/fs/nfsd/nfsproc.c b/fs/nfsd/nfsproc.c
index 5cc2eec981b..b2c7147aa92 100644
--- a/fs/nfsd/nfsproc.c
+++ b/fs/nfsd/nfsproc.c
@@ -155,7 +155,7 @@ nfsd_proc_read(struct svc_rqst *rqstp, struct nfsd_readargs *argp,
argp->count = NFSSVC_MAXBLKSIZE_V2;
- svc_reserve(rqstp, (19<<2) + argp->count + 4);
+ svc_reserve_auth(rqstp, (19<<2) + argp->count + 4);
resp->count = argp->count;
nfserr = nfsd_read(rqstp, fh_copy(&resp->fh, &argp->fh), NULL,
diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index 35fa4d5aadd..4a7ae8ab6eb 100644
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -396,4 +396,23 @@ char * svc_print_addr(struct svc_rqst *, char *, size_t);
+ * When we want to reduce the size of the reserved space in the response
+ * buffer, we need to take into account the size of any checksum data that
+ * may be at the end of the packet. This is difficult to determine exactly
+ * for all cases without actually generating the checksum, so we just use a
+ * static value.
+ */
+static inline void
+svc_reserve_auth(struct svc_rqst *rqstp, int space)
+ int added_space = 0;
+ switch(rqstp->rq_authop->flavour) {
+ case RPC_AUTH_GSS:
+ added_space = RPC_MAX_AUTH_SIZE;
+ }
+ return svc_reserve(rqstp, space + added_space);
#endif /* SUNRPC_SVC_H */
diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index b7503c103ae..e673ef99390 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -907,7 +907,7 @@ svc_process(struct svc_rqst *rqstp)
* better idea of reply size
if (procp->pc_xdrressize)
- svc_reserve(rqstp, procp->pc_xdrressize<<2);
+ svc_reserve_auth(rqstp, procp->pc_xdrressize<<2);
/* Call the function that processes the request. */
if (!versp->vs_dispatch) {