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NFS: Ensure the client submounts, when it crosses a server mountpoint.
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Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
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Trond Myklebust authored and Trond Myklebust committed Jun 9, 2006
1 parent 8b4bdcf commit 55a9759
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Showing 7 changed files with 418 additions and 5 deletions.
3 changes: 2 additions & 1 deletion fs/nfs/Makefile
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Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,8 @@
obj-$(CONFIG_NFS_FS) += nfs.o

nfs-y := dir.o file.o inode.o nfs2xdr.o pagelist.o \
proc.o read.o symlink.o unlink.o write.o
proc.o read.o symlink.o unlink.o write.o \
namespace.o
nfs-$(CONFIG_ROOT_NFS) += nfsroot.o mount_clnt.o
nfs-$(CONFIG_NFS_V3) += nfs3proc.o nfs3xdr.o
nfs-$(CONFIG_NFS_V3_ACL) += nfs3acl.o
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16 changes: 16 additions & 0 deletions fs/nfs/dir.c
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Original file line number Diff line number Diff line change
Expand Up @@ -868,6 +868,17 @@ int nfs_is_exclusive_create(struct inode *dir, struct nameidata *nd)
return (nd->intent.open.flags & O_EXCL) != 0;
}

static inline int nfs_reval_fsid(struct inode *dir,
struct nfs_fh *fh, struct nfs_fattr *fattr)
{
struct nfs_server *server = NFS_SERVER(dir);

if (!nfs_fsid_equal(&server->fsid, &fattr->fsid))
/* Revalidate fsid on root dir */
return __nfs_revalidate_inode(server, dir->i_sb->s_root->d_inode);
return 0;
}

static struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry, struct nameidata *nd)
{
struct dentry *res;
Expand Down Expand Up @@ -900,6 +911,11 @@ static struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry, stru
res = ERR_PTR(error);
goto out_unlock;
}
error = nfs_reval_fsid(dir, &fhandle, &fattr);
if (error < 0) {
res = ERR_PTR(error);
goto out_unlock;
}
inode = nfs_fhget(dentry->d_sb, &fhandle, &fattr);
res = (struct dentry *)inode;
if (IS_ERR(res))
Expand Down
303 changes: 300 additions & 3 deletions fs/nfs/inode.c
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Original file line number Diff line number Diff line change
Expand Up @@ -221,6 +221,14 @@ nfs_block_size(unsigned long bsize, unsigned char *nrbitsp)
return nfs_block_bits(bsize, nrbitsp);
}

static inline void
nfs_super_set_maxbytes(struct super_block *sb, __u64 maxfilesize)
{
sb->s_maxbytes = (loff_t)maxfilesize;
if (sb->s_maxbytes > MAX_LFS_FILESIZE || sb->s_maxbytes <= 0)
sb->s_maxbytes = MAX_LFS_FILESIZE;
}

/*
* Obtain the root inode of the file system.
*/
Expand Down Expand Up @@ -331,9 +339,7 @@ nfs_sb_init(struct super_block *sb, rpc_authflavor_t authflavor)
}
server->backing_dev_info.ra_pages = server->rpages * NFS_MAX_READAHEAD;

sb->s_maxbytes = fsinfo.maxfilesize;
if (sb->s_maxbytes > MAX_LFS_FILESIZE)
sb->s_maxbytes = MAX_LFS_FILESIZE;
nfs_super_set_maxbytes(sb, fsinfo.maxfilesize);

server->client->cl_intr = (server->flags & NFS_MOUNT_INTR) ? 1 : 0;
server->client->cl_softrtry = (server->flags & NFS_MOUNT_SOFT) ? 1 : 0;
Expand Down Expand Up @@ -877,6 +883,11 @@ nfs_fhget(struct super_block *sb, struct nfs_fh *fh, struct nfs_fattr *fattr)
if (nfs_server_capable(inode, NFS_CAP_READDIRPLUS)
&& fattr->size <= NFS_LIMIT_READDIRPLUS)
set_bit(NFS_INO_ADVISE_RDPLUS, &NFS_FLAGS(inode));
/* Deal with crossing mountpoints */
if (!nfs_fsid_equal(&NFS_SB(sb)->fsid, &fattr->fsid)) {
inode->i_op = &nfs_mountpoint_inode_operations;
inode->i_fop = NULL;
}
} else if (S_ISLNK(inode->i_mode))
inode->i_op = &nfs_symlink_inode_operations;
else
Expand Down Expand Up @@ -1650,6 +1661,141 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr)
* File system information
*/

/*
* nfs_path - reconstruct the path given an arbitrary dentry
* @base - arbitrary string to prepend to the path
* @dentry - pointer to dentry
* @buffer - result buffer
* @buflen - length of buffer
*
* Helper function for constructing the path from the
* root dentry to an arbitrary hashed dentry.
*
* This is mainly for use in figuring out the path on the
* server side when automounting on top of an existing partition.
*/
static char *nfs_path(const char *base, const struct dentry *dentry,
char *buffer, ssize_t buflen)
{
char *end = buffer+buflen;
int namelen;

*--end = '\0';
buflen--;
spin_lock(&dcache_lock);
while (!IS_ROOT(dentry)) {
namelen = dentry->d_name.len;
buflen -= namelen + 1;
if (buflen < 0)
goto Elong;
end -= namelen;
memcpy(end, dentry->d_name.name, namelen);
*--end = '/';
dentry = dentry->d_parent;
}
spin_unlock(&dcache_lock);
namelen = strlen(base);
/* Strip off excess slashes in base string */
while (namelen > 0 && base[namelen - 1] == '/')
namelen--;
buflen -= namelen;
if (buflen < 0)
goto Elong;
end -= namelen;
memcpy(end, base, namelen);
return end;
Elong:
return ERR_PTR(-ENAMETOOLONG);
}

struct nfs_clone_mount {
const struct super_block *sb;
const struct dentry *dentry;
struct nfs_fh *fh;
struct nfs_fattr *fattr;
};

static struct super_block *nfs_clone_generic_sb(struct nfs_clone_mount *data,
struct super_block *(*clone_client)(struct nfs_server *, struct nfs_clone_mount *))
{
struct nfs_server *server;
struct nfs_server *parent = NFS_SB(data->sb);
struct super_block *sb = ERR_PTR(-EINVAL);
void *err = ERR_PTR(-ENOMEM);
struct inode *root_inode;
struct nfs_fsinfo fsinfo;
int len;

server = kmalloc(sizeof(struct nfs_server), GFP_KERNEL);
if (server == NULL)
goto out_err;
memcpy(server, parent, sizeof(*server));
len = strlen(parent->hostname) + 1;
server->hostname = kmalloc(len, GFP_KERNEL);
if (server->hostname == NULL)
goto free_server;
memcpy(server->hostname, parent->hostname, len);
server->fsid = data->fattr->fsid;
nfs_copy_fh(&server->fh, data->fh);
if (rpciod_up() != 0)
goto free_hostname;

sb = clone_client(server, data);
if (IS_ERR((err = sb)) || sb->s_root)
goto kill_rpciod;

sb->s_op = data->sb->s_op;
sb->s_blocksize = data->sb->s_blocksize;
sb->s_blocksize_bits = data->sb->s_blocksize_bits;
sb->s_maxbytes = data->sb->s_maxbytes;

server->client_sys = server->client_acl = ERR_PTR(-EINVAL);
err = ERR_PTR(-ENOMEM);
server->io_stats = nfs_alloc_iostats();
if (server->io_stats == NULL)
goto out_deactivate;

server->client = rpc_clone_client(parent->client);
if (IS_ERR((err = server->client)))
goto out_deactivate;
if (!IS_ERR(parent->client_sys)) {
server->client_sys = rpc_clone_client(parent->client_sys);
if (IS_ERR((err = server->client_sys)))
goto out_deactivate;
}
if (!IS_ERR(parent->client_acl)) {
server->client_acl = rpc_clone_client(parent->client_acl);
if (IS_ERR((err = server->client_acl)))
goto out_deactivate;
}
root_inode = nfs_fhget(sb, data->fh, data->fattr);
if (!root_inode)
goto out_deactivate;
sb->s_root = d_alloc_root(root_inode);
if (!sb->s_root)
goto out_put_root;
fsinfo.fattr = data->fattr;
if (NFS_PROTO(root_inode)->fsinfo(server, data->fh, &fsinfo) == 0)
nfs_super_set_maxbytes(sb, fsinfo.maxfilesize);
sb->s_root->d_op = server->rpc_ops->dentry_ops;
sb->s_flags |= MS_ACTIVE;
return sb;
out_put_root:
iput(root_inode);
out_deactivate:
up_write(&sb->s_umount);
deactivate_super(sb);
return (struct super_block *)err;
kill_rpciod:
rpciod_down();
free_hostname:
kfree(server->hostname);
free_server:
kfree(server);
out_err:
return (struct super_block *)err;
}

static int nfs_set_super(struct super_block *s, void *data)
{
s->s_fs_info = data;
Expand Down Expand Up @@ -1807,6 +1953,31 @@ static struct file_system_type nfs_fs_type = {
.fs_flags = FS_ODD_RENAME|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
};

static struct super_block *nfs_clone_client(struct nfs_server *server, struct nfs_clone_mount *data)
{
struct super_block *sb;

sb = sget(&nfs_fs_type, nfs_compare_super, nfs_set_super, server);
if (!IS_ERR(sb) && sb->s_root == NULL && !(server->flags & NFS_MOUNT_NONLM))
lockd_up();
return sb;
}

static struct super_block *nfs_clone_nfs_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *raw_data)
{
struct nfs_clone_mount *data = raw_data;
return nfs_clone_generic_sb(data, nfs_clone_client);
}

static struct file_system_type clone_nfs_fs_type = {
.owner = THIS_MODULE,
.name = "nfs",
.get_sb = nfs_clone_nfs_sb,
.kill_sb = nfs_kill_super,
.fs_flags = FS_ODD_RENAME|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
};

#ifdef CONFIG_NFS_V4

static void nfs4_clear_inode(struct inode *);
Expand Down Expand Up @@ -2156,6 +2327,75 @@ static int param_set_idmap_timeout(const char *val, struct kernel_param *kp)
module_param_call(idmap_cache_timeout, param_set_idmap_timeout, param_get_int,
&nfs_idmap_cache_timeout, 0644);

/* Constructs the SERVER-side path */
static inline char *nfs4_path(const struct dentry *dentry, char *buffer, ssize_t buflen)
{
return nfs_path(NFS_SB(dentry->d_sb)->mnt_path, dentry, buffer, buflen);
}

static inline char *nfs4_dup_path(const struct dentry *dentry)
{
char *page = (char *) __get_free_page(GFP_USER);
char *path;

path = nfs4_path(dentry, page, PAGE_SIZE);
if (!IS_ERR(path)) {
int len = PAGE_SIZE + page - path;
char *tmp = path;

path = kmalloc(len, GFP_KERNEL);
if (path)
memcpy(path, tmp, len);
else
path = ERR_PTR(-ENOMEM);
}
free_page((unsigned long)page);
return path;
}

static struct super_block *nfs4_clone_client(struct nfs_server *server, struct nfs_clone_mount *data)
{
const struct dentry *dentry = data->dentry;
struct nfs4_client *clp = server->nfs4_state;
struct super_block *sb;

server->mnt_path = nfs4_dup_path(dentry);
if (IS_ERR(server->mnt_path)) {
sb = (struct super_block *)server->mnt_path;
goto err;
}
sb = sget(&nfs4_fs_type, nfs4_compare_super, nfs_set_super, server);
if (IS_ERR(sb) || sb->s_root)
goto free_path;
nfs4_server_capabilities(server, &server->fh);

down_write(&clp->cl_sem);
atomic_inc(&clp->cl_count);
list_add_tail(&server->nfs4_siblings, &clp->cl_superblocks);
up_write(&clp->cl_sem);
return sb;
free_path:
kfree(server->mnt_path);
err:
server->mnt_path = NULL;
return sb;
}

static struct super_block *nfs_clone_nfs4_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *raw_data)
{
struct nfs_clone_mount *data = raw_data;
return nfs_clone_generic_sb(data, nfs4_clone_client);
}

static struct file_system_type clone_nfs4_fs_type = {
.owner = THIS_MODULE,
.name = "nfs",
.get_sb = nfs_clone_nfs4_sb,
.kill_sb = nfs4_kill_super,
.fs_flags = FS_ODD_RENAME|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
};

#define nfs4_init_once(nfsi) \
do { \
INIT_LIST_HEAD(&(nfsi)->open_states); \
Expand Down Expand Up @@ -2183,12 +2423,69 @@ static inline void unregister_nfs4fs(void)
nfs_unregister_sysctl();
}
#else
#define nfs4_clone_client(a,b) ERR_PTR(-EINVAL)
#define nfs4_init_once(nfsi) \
do { } while (0)
#define register_nfs4fs() (0)
#define unregister_nfs4fs()
#endif

static inline char *nfs_devname(const struct vfsmount *mnt_parent,
const struct dentry *dentry,
char *buffer, ssize_t buflen)
{
return nfs_path(mnt_parent->mnt_devname, dentry, buffer, buflen);
}

/**
* nfs_do_submount - set up mountpoint when crossing a filesystem boundary
* @mnt_parent - mountpoint of parent directory
* @dentry - parent directory
* @fh - filehandle for new root dentry
* @fattr - attributes for new root inode
*
*/
struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
const struct dentry *dentry, struct nfs_fh *fh,
struct nfs_fattr *fattr)
{
struct nfs_clone_mount mountdata = {
.sb = mnt_parent->mnt_sb,
.dentry = dentry,
.fh = fh,
.fattr = fattr,
};
struct vfsmount *mnt = ERR_PTR(-ENOMEM);
char *page = (char *) __get_free_page(GFP_USER);
char *devname;

dprintk("%s: submounting on %s/%s\n", __FUNCTION__,
dentry->d_parent->d_name.name,
dentry->d_name.name);
if (page == NULL)
goto out;
devname = nfs_devname(mnt_parent, dentry, page, PAGE_SIZE);
mnt = (struct vfsmount *)devname;
if (IS_ERR(devname))
goto free_page;
switch (NFS_SB(mnt_parent->mnt_sb)->rpc_ops->version) {
case 2:
case 3:
mnt = vfs_kern_mount(&clone_nfs_fs_type, 0, devname, &mountdata);
break;
case 4:
mnt = vfs_kern_mount(&clone_nfs4_fs_type, 0, devname, &mountdata);
break;
default:
BUG();
}
free_page:
free_page((unsigned long)page);
out:
dprintk("%s: done\n", __FUNCTION__);
return mnt;
}

extern int nfs_init_nfspagecache(void);
extern void nfs_destroy_nfspagecache(void);
extern int nfs_init_readpagecache(void);
Expand Down
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