mirror of
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2025-08-05 16:54:27 +00:00
nfs_localio: simplify interface to nfsd for getting nfsd_file
The nfsd_localio_operations structure contains nfsd_file_get() to get a
reference to an nfsd_file. This is only used in one place, where
nfsd_open_local_fh() is also used.
This patch combines the two, calling nfsd_open_local_fh() passing a
pointer to where the nfsd_file pointer might be stored. If there is a
pointer there an nfsd_file_get() can get a reference, that reference is
returned. If not a new nfsd_file is acquired, stored at the pointer,
and returned. When we store a reference we also increase the refcount
on the net, as that refcount is decrements when we clear the stored
pointer.
We now get an extra reference *before* storing the new nfsd_file at the
given location. This avoids possible races with the nfsd_file being
freed before the final reference can be taken.
This patch moves the rcu_dereference() needed after fetching from
ro_file or rw_file into the nfsd code where the 'struct nfs_file' is
fully defined. This avoids an error reported by older versions of gcc
such as gcc-8 which complain about rcu_dereference() use in contexts
where the structure (which will supposedly be accessed) is not fully
defined.
Reported-by: Pali Rohár <pali@kernel.org>
Reported-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Fixes: 86e0041225 ("nfs: cache all open LOCALIO nfsd_file(s) in client")
Signed-off-by: NeilBrown <neil@brown.name>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
This commit is contained in:
NeilBrown
Anna Schumaker
parent
77e82fb2c6
commit
e6f7e1487a
3 changed files with 55 additions and 44 deletions
|
|
@ -209,11 +209,6 @@ void nfs_local_probe_async(struct nfs_client *clp)
|
|||
}
|
||||
EXPORT_SYMBOL_GPL(nfs_local_probe_async);
|
||||
|
||||
static inline struct nfsd_file *nfs_local_file_get(struct nfsd_file *nf)
|
||||
{
|
||||
return nfs_to->nfsd_file_get_local(nf);
|
||||
}
|
||||
|
||||
static inline void nfs_local_file_put(struct nfsd_file *nf)
|
||||
{
|
||||
nfs_to_nfsd_file_put_local(nf);
|
||||
|
|
@ -228,12 +223,13 @@ static inline void nfs_local_file_put(struct nfsd_file *nf)
|
|||
static struct nfsd_file *
|
||||
__nfs_local_open_fh(struct nfs_client *clp, const struct cred *cred,
|
||||
struct nfs_fh *fh, struct nfs_file_localio *nfl,
|
||||
struct nfsd_file __rcu **pnf,
|
||||
const fmode_t mode)
|
||||
{
|
||||
struct nfsd_file *localio;
|
||||
|
||||
localio = nfs_open_local_fh(&clp->cl_uuid, clp->cl_rpcclient,
|
||||
cred, fh, nfl, mode);
|
||||
cred, fh, nfl, pnf, mode);
|
||||
if (IS_ERR(localio)) {
|
||||
int status = PTR_ERR(localio);
|
||||
trace_nfs_local_open_fh(fh, mode, status);
|
||||
|
|
@ -260,7 +256,7 @@ nfs_local_open_fh(struct nfs_client *clp, const struct cred *cred,
|
|||
struct nfs_fh *fh, struct nfs_file_localio *nfl,
|
||||
const fmode_t mode)
|
||||
{
|
||||
struct nfsd_file *nf, *new, __rcu **pnf;
|
||||
struct nfsd_file *nf, __rcu **pnf;
|
||||
|
||||
if (!nfs_server_is_local(clp))
|
||||
return NULL;
|
||||
|
|
@ -272,24 +268,9 @@ nfs_local_open_fh(struct nfs_client *clp, const struct cred *cred,
|
|||
else
|
||||
pnf = &nfl->ro_file;
|
||||
|
||||
new = NULL;
|
||||
rcu_read_lock();
|
||||
nf = rcu_dereference(*pnf);
|
||||
if (!nf) {
|
||||
rcu_read_unlock();
|
||||
new = __nfs_local_open_fh(clp, cred, fh, nfl, mode);
|
||||
if (IS_ERR(new))
|
||||
return NULL;
|
||||
rcu_read_lock();
|
||||
/* try to swap in the pointer */
|
||||
nf = unrcu_pointer(cmpxchg(pnf, NULL, RCU_INITIALIZER(new)));
|
||||
if (!nf)
|
||||
swap(nf, new);
|
||||
}
|
||||
nf = nfs_local_file_get(nf);
|
||||
rcu_read_unlock();
|
||||
if (new)
|
||||
nfs_to_nfsd_file_put_local(new);
|
||||
nf = __nfs_local_open_fh(clp, cred, fh, nfl, pnf, mode);
|
||||
if (IS_ERR(nf))
|
||||
return NULL;
|
||||
return nf;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(nfs_local_open_fh);
|
||||
|
|
|
|||
|
|
@ -237,6 +237,7 @@ static void nfs_uuid_add_file(nfs_uuid_t *nfs_uuid, struct nfs_file_localio *nfl
|
|||
struct nfsd_file *nfs_open_local_fh(nfs_uuid_t *uuid,
|
||||
struct rpc_clnt *rpc_clnt, const struct cred *cred,
|
||||
const struct nfs_fh *nfs_fh, struct nfs_file_localio *nfl,
|
||||
struct nfsd_file __rcu **pnf,
|
||||
const fmode_t fmode)
|
||||
{
|
||||
struct net *net;
|
||||
|
|
@ -261,7 +262,7 @@ struct nfsd_file *nfs_open_local_fh(nfs_uuid_t *uuid,
|
|||
rcu_read_unlock();
|
||||
/* We have an implied reference to net thanks to nfsd_net_try_get */
|
||||
localio = nfs_to->nfsd_open_local_fh(net, uuid->dom, rpc_clnt,
|
||||
cred, nfs_fh, fmode);
|
||||
cred, nfs_fh, pnf, fmode);
|
||||
nfs_to_nfsd_net_put(net);
|
||||
if (!IS_ERR(localio))
|
||||
nfs_uuid_add_file(uuid, nfl);
|
||||
|
|
|
|||
|
|
@ -24,20 +24,6 @@
|
|||
#include "filecache.h"
|
||||
#include "cache.h"
|
||||
|
||||
static const struct nfsd_localio_operations nfsd_localio_ops = {
|
||||
.nfsd_net_try_get = nfsd_net_try_get,
|
||||
.nfsd_net_put = nfsd_net_put,
|
||||
.nfsd_open_local_fh = nfsd_open_local_fh,
|
||||
.nfsd_file_put_local = nfsd_file_put_local,
|
||||
.nfsd_file_get_local = nfsd_file_get_local,
|
||||
.nfsd_file_file = nfsd_file_file,
|
||||
};
|
||||
|
||||
void nfsd_localio_ops_init(void)
|
||||
{
|
||||
nfs_to = &nfsd_localio_ops;
|
||||
}
|
||||
|
||||
/**
|
||||
* nfsd_open_local_fh - lookup a local filehandle @nfs_fh and map to nfsd_file
|
||||
*
|
||||
|
|
@ -46,6 +32,7 @@ void nfsd_localio_ops_init(void)
|
|||
* @rpc_clnt: rpc_clnt that the client established
|
||||
* @cred: cred that the client established
|
||||
* @nfs_fh: filehandle to lookup
|
||||
* @nfp: place to find the nfsd_file, or store it if it was non-NULL
|
||||
* @fmode: fmode_t to use for open
|
||||
*
|
||||
* This function maps a local fh to a path on a local filesystem.
|
||||
|
|
@ -56,10 +43,11 @@ void nfsd_localio_ops_init(void)
|
|||
* set. Caller (NFS client) is responsible for calling nfsd_net_put and
|
||||
* nfsd_file_put (via nfs_to_nfsd_file_put_local).
|
||||
*/
|
||||
struct nfsd_file *
|
||||
static struct nfsd_file *
|
||||
nfsd_open_local_fh(struct net *net, struct auth_domain *dom,
|
||||
struct rpc_clnt *rpc_clnt, const struct cred *cred,
|
||||
const struct nfs_fh *nfs_fh, const fmode_t fmode)
|
||||
const struct nfs_fh *nfs_fh, struct nfsd_file __rcu **pnf,
|
||||
const fmode_t fmode)
|
||||
{
|
||||
int mayflags = NFSD_MAY_LOCALIO;
|
||||
struct svc_cred rq_cred;
|
||||
|
|
@ -73,6 +61,12 @@ nfsd_open_local_fh(struct net *net, struct auth_domain *dom,
|
|||
if (!nfsd_net_try_get(net))
|
||||
return ERR_PTR(-ENXIO);
|
||||
|
||||
rcu_read_lock();
|
||||
localio = nfsd_file_get(rcu_dereference(*pnf));
|
||||
rcu_read_unlock();
|
||||
if (localio)
|
||||
return localio;
|
||||
|
||||
/* nfs_fh -> svc_fh */
|
||||
fh_init(&fh, NFS4_FHSIZE);
|
||||
fh.fh_handle.fh_size = nfs_fh->size;
|
||||
|
|
@ -94,12 +88,47 @@ nfsd_open_local_fh(struct net *net, struct auth_domain *dom,
|
|||
if (rq_cred.cr_group_info)
|
||||
put_group_info(rq_cred.cr_group_info);
|
||||
|
||||
if (IS_ERR(localio))
|
||||
if (!IS_ERR(localio)) {
|
||||
struct nfsd_file *new;
|
||||
if (!nfsd_net_try_get(net)) {
|
||||
nfsd_file_put(localio);
|
||||
nfsd_net_put(net);
|
||||
return ERR_PTR(-ENXIO);
|
||||
}
|
||||
nfsd_file_get(localio);
|
||||
again:
|
||||
new = unrcu_pointer(cmpxchg(pnf, NULL, RCU_INITIALIZER(localio)));
|
||||
if (new) {
|
||||
/* Some other thread installed an nfsd_file */
|
||||
if (nfsd_file_get(new) == NULL)
|
||||
goto again;
|
||||
/*
|
||||
* Drop the ref we were going to install and the
|
||||
* one we were going to return.
|
||||
*/
|
||||
nfsd_file_put(localio);
|
||||
nfsd_file_put(localio);
|
||||
localio = new;
|
||||
}
|
||||
} else
|
||||
nfsd_net_put(net);
|
||||
|
||||
return localio;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(nfsd_open_local_fh);
|
||||
|
||||
static const struct nfsd_localio_operations nfsd_localio_ops = {
|
||||
.nfsd_net_try_get = nfsd_net_try_get,
|
||||
.nfsd_net_put = nfsd_net_put,
|
||||
.nfsd_open_local_fh = nfsd_open_local_fh,
|
||||
.nfsd_file_put_local = nfsd_file_put_local,
|
||||
.nfsd_file_get_local = nfsd_file_get_local,
|
||||
.nfsd_file_file = nfsd_file_file,
|
||||
};
|
||||
|
||||
void nfsd_localio_ops_init(void)
|
||||
{
|
||||
nfs_to = &nfsd_localio_ops;
|
||||
}
|
||||
|
||||
/*
|
||||
* UUID_IS_LOCAL XDR functions
|
||||
|
|
|
|||
Loading…
Add table
Reference in a new issue