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linux/fs/nfs/export.c
J. Bruce Fields f657f8eef3 nfs: don't atempt blocking locks on nfs reexports
NFS implements blocking locks by blocking inside its lock method.  In
the reexport case, this blocks the nfs server thread, which could lead
to deadlocks since an nfs server thread might be required to unlock the
conflicting lock.  It also causes a crash, since the nfs server thread
assumes it can free the lock when its lm_notify lock callback is called.

Ideal would be to make the nfs lock method return without blocking in
this case, but for now it works just not to attempt blocking locks.  The
difference is just that the original client will have to poll (as it
does in the v4.0 case) instead of getting a callback when the lock's
available.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Acked-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2021-08-26 15:32:10 -04:00

185 lines
4.5 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2015, Primary Data, Inc. All rights reserved.
*
* Tao Peng <bergwolf@primarydata.com>
*/
#include <linux/dcache.h>
#include <linux/exportfs.h>
#include <linux/nfs.h>
#include <linux/nfs_fs.h>
#include "internal.h"
#include "nfstrace.h"
#define NFSDBG_FACILITY NFSDBG_VFS
enum {
FILEID_HIGH_OFF = 0, /* inode fileid high */
FILEID_LOW_OFF, /* inode fileid low */
FILE_I_TYPE_OFF, /* inode type */
EMBED_FH_OFF /* embeded server fh */
};
static struct nfs_fh *nfs_exp_embedfh(__u32 *p)
{
return (struct nfs_fh *)(p + EMBED_FH_OFF);
}
/*
* Let's break subtree checking for now... otherwise we'll have to embed parent fh
* but there might not be enough space.
*/
static int
nfs_encode_fh(struct inode *inode, __u32 *p, int *max_len, struct inode *parent)
{
struct nfs_fh *server_fh = NFS_FH(inode);
struct nfs_fh *clnt_fh = nfs_exp_embedfh(p);
size_t fh_size = offsetof(struct nfs_fh, data) + server_fh->size;
int len = EMBED_FH_OFF + XDR_QUADLEN(fh_size);
dprintk("%s: max fh len %d inode %p parent %p",
__func__, *max_len, inode, parent);
if (*max_len < len || IS_AUTOMOUNT(inode)) {
dprintk("%s: fh len %d too small, required %d\n",
__func__, *max_len, len);
*max_len = len;
return FILEID_INVALID;
}
p[FILEID_HIGH_OFF] = NFS_FILEID(inode) >> 32;
p[FILEID_LOW_OFF] = NFS_FILEID(inode);
p[FILE_I_TYPE_OFF] = inode->i_mode & S_IFMT;
p[len - 1] = 0; /* Padding */
nfs_copy_fh(clnt_fh, server_fh);
*max_len = len;
dprintk("%s: result fh fileid %llu mode %u size %d\n",
__func__, NFS_FILEID(inode), inode->i_mode, *max_len);
return *max_len;
}
static struct dentry *
nfs_fh_to_dentry(struct super_block *sb, struct fid *fid,
int fh_len, int fh_type)
{
struct nfs4_label *label = NULL;
struct nfs_fattr *fattr = NULL;
struct nfs_fh *server_fh = nfs_exp_embedfh(fid->raw);
size_t fh_size = offsetof(struct nfs_fh, data) + server_fh->size;
const struct nfs_rpc_ops *rpc_ops;
struct dentry *dentry;
struct inode *inode;
int len = EMBED_FH_OFF + XDR_QUADLEN(fh_size);
u32 *p = fid->raw;
int ret;
/* NULL translates to ESTALE */
if (fh_len < len || fh_type != len)
return NULL;
fattr = nfs_alloc_fattr();
if (fattr == NULL) {
dentry = ERR_PTR(-ENOMEM);
goto out;
}
fattr->fileid = ((u64)p[FILEID_HIGH_OFF] << 32) + p[FILEID_LOW_OFF];
fattr->mode = p[FILE_I_TYPE_OFF];
fattr->valid |= NFS_ATTR_FATTR_FILEID | NFS_ATTR_FATTR_TYPE;
dprintk("%s: fileid %llu mode %d\n", __func__, fattr->fileid, fattr->mode);
inode = nfs_ilookup(sb, fattr, server_fh);
if (inode)
goto out_found;
label = nfs4_label_alloc(NFS_SB(sb), GFP_KERNEL);
if (IS_ERR(label)) {
dentry = ERR_CAST(label);
goto out_free_fattr;
}
rpc_ops = NFS_SB(sb)->nfs_client->rpc_ops;
ret = rpc_ops->getattr(NFS_SB(sb), server_fh, fattr, label, NULL);
if (ret) {
dprintk("%s: getattr failed %d\n", __func__, ret);
trace_nfs_fh_to_dentry(sb, server_fh, fattr->fileid, ret);
dentry = ERR_PTR(ret);
goto out_free_label;
}
inode = nfs_fhget(sb, server_fh, fattr, label);
out_found:
dentry = d_obtain_alias(inode);
out_free_label:
nfs4_label_free(label);
out_free_fattr:
nfs_free_fattr(fattr);
out:
return dentry;
}
static struct dentry *
nfs_get_parent(struct dentry *dentry)
{
int ret;
struct inode *inode = d_inode(dentry), *pinode;
struct super_block *sb = inode->i_sb;
struct nfs_server *server = NFS_SB(sb);
struct nfs_fattr *fattr = NULL;
struct nfs4_label *label = NULL;
struct dentry *parent;
struct nfs_rpc_ops const *ops = server->nfs_client->rpc_ops;
struct nfs_fh fh;
if (!ops->lookupp)
return ERR_PTR(-EACCES);
fattr = nfs_alloc_fattr();
if (fattr == NULL) {
parent = ERR_PTR(-ENOMEM);
goto out;
}
label = nfs4_label_alloc(server, GFP_KERNEL);
if (IS_ERR(label)) {
parent = ERR_CAST(label);
goto out_free_fattr;
}
ret = ops->lookupp(inode, &fh, fattr, label);
if (ret) {
parent = ERR_PTR(ret);
goto out_free_label;
}
pinode = nfs_fhget(sb, &fh, fattr, label);
parent = d_obtain_alias(pinode);
out_free_label:
nfs4_label_free(label);
out_free_fattr:
nfs_free_fattr(fattr);
out:
return parent;
}
static u64 nfs_fetch_iversion(struct inode *inode)
{
nfs_revalidate_inode(inode, NFS_INO_INVALID_CHANGE);
return inode_peek_iversion_raw(inode);
}
const struct export_operations nfs_export_ops = {
.encode_fh = nfs_encode_fh,
.fh_to_dentry = nfs_fh_to_dentry,
.get_parent = nfs_get_parent,
.fetch_iversion = nfs_fetch_iversion,
.flags = EXPORT_OP_NOWCC|EXPORT_OP_NOSUBTREECHK|
EXPORT_OP_CLOSE_BEFORE_UNLINK|EXPORT_OP_REMOTE_FS|
EXPORT_OP_NOATOMIC_ATTR|EXPORT_OP_SYNC_LOCKS,
};