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NFS: Define and create superblock-level objects 

Define and create superblock-level cache index objects (as managed by
nfs_server structs).

Each superblock object is created in a server level index object and is itself
an index into which inode-level objects are inserted.

Ideally there would be one superblock-level object per server, and the former
would be folded into the latter; however, since the "nosharecache" option
exists this isn't possible.

The superblock object key is a sequence consisting of:

 (1) Certain superblock s_flags.

 (2) Various connection parameters that serve to distinguish superblocks for
     sget().

 (3) The volume FSID.

 (4) The security flavour.

 (5) The uniquifier length.

 (6) The uniquifier text.  This is normally an empty string, unless the fsc=xyz
     mount option was used to explicitly specify a uniquifier.

The key blob is of variable length, depending on the length of (6).

The superblock object is given no coherency data to carry in the auxiliary data
permitted by the cache.  It is assumed that the superblock is always coherent.

This patch also adds uniquification handling such that two otherwise identical
superblocks, at least one of which is marked "nosharecache", won't end up
trying to share the on-disk cache.  It will be possible to manually provide a
uniquifier through a mount option with a later patch to avoid the error
otherwise produced.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
This commit is contained in:
David Howells 2009-04-03 16:42:42 +01:00
parent 147272813e
commit 08734048b3
6 changed files with 214 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
fs/nfs/fscache-index.c
View File

@ -112,3 +112,37 @@ const struct fscache_cookie_def nfs_fscache_server_index_def = {
.type = FSCACHE_COOKIE_TYPE_INDEX,
.get_key = nfs_server_get_key,
};
/*
* Generate a key to describe a superblock key in the main NFS index
*/
static uint16_t nfs_super_get_key(const void *cookie_netfs_data,
void *buffer, uint16_t bufmax)
{
const struct nfs_fscache_key *key;
const struct nfs_server *nfss = cookie_netfs_data;
uint16_t len;
key = nfss->fscache_key;
len = sizeof(key->key) + key->key.uniq_len;
if (len > bufmax) {
len = 0;
} else {
memcpy(buffer, &key->key, sizeof(key->key));
memcpy(buffer + sizeof(key->key),
key->key.uniquifier, key->key.uniq_len);
}
return len;
}
/*
* Define the superblock object for FS-Cache. This is used to describe a
* superblock object to fscache_acquire_cookie(). It is keyed by all the NFS
* parameters that might cause a separate superblock.
*/
const struct fscache_cookie_def nfs_fscache_super_index_def = {
.name = "NFS.super",
.type = FSCACHE_COOKIE_TYPE_INDEX,
.get_key = nfs_super_get_key,
};

116
fs/nfs/fscache.c
View File

@ -23,6 +23,9 @@
#define NFSDBG_FACILITY NFSDBG_FSCACHE
static struct rb_root nfs_fscache_keys = RB_ROOT;
static DEFINE_SPINLOCK(nfs_fscache_keys_lock);
/*
* Get the per-client index cookie for an NFS client if the appropriate mount
* flag was set
@ -50,3 +53,116 @@ void nfs_fscache_release_client_cookie(struct nfs_client *clp)
fscache_relinquish_cookie(clp->fscache, 0);
clp->fscache = NULL;
}
/*
* Get the cache cookie for an NFS superblock. We have to handle
* uniquification here because the cache doesn't do it for us.
*/
void nfs_fscache_get_super_cookie(struct super_block *sb,
struct nfs_parsed_mount_data *data)
{
struct nfs_fscache_key *key, *xkey;
struct nfs_server *nfss = NFS_SB(sb);
struct rb_node **p, *parent;
const char *uniq = data->fscache_uniq ?: "";
int diff, ulen;
ulen = strlen(uniq);
key = kzalloc(sizeof(*key) + ulen, GFP_KERNEL);
if (!key)
return;
key->nfs_client = nfss->nfs_client;
key->key.super.s_flags = sb->s_flags & NFS_MS_MASK;
key->key.nfs_server.flags = nfss->flags;
key->key.nfs_server.rsize = nfss->rsize;
key->key.nfs_server.wsize = nfss->wsize;
key->key.nfs_server.acregmin = nfss->acregmin;
key->key.nfs_server.acregmax = nfss->acregmax;
key->key.nfs_server.acdirmin = nfss->acdirmin;
key->key.nfs_server.acdirmax = nfss->acdirmax;
key->key.nfs_server.fsid = nfss->fsid;
key->key.rpc_auth.au_flavor = nfss->client->cl_auth->au_flavor;
key->key.uniq_len = ulen;
memcpy(key->key.uniquifier, uniq, ulen);
spin_lock(&nfs_fscache_keys_lock);
p = &nfs_fscache_keys.rb_node;
parent = NULL;
while (*p) {
parent = *p;
xkey = rb_entry(parent, struct nfs_fscache_key, node);
if (key->nfs_client < xkey->nfs_client)
goto go_left;
if (key->nfs_client > xkey->nfs_client)
goto go_right;
diff = memcmp(&key->key, &xkey->key, sizeof(key->key));
if (diff < 0)
goto go_left;
if (diff > 0)
goto go_right;
if (key->key.uniq_len == 0)
goto non_unique;
diff = memcmp(key->key.uniquifier,
xkey->key.uniquifier,
key->key.uniq_len);
if (diff < 0)
goto go_left;
if (diff > 0)
goto go_right;
goto non_unique;
go_left:
p = &(*p)->rb_left;
continue;
go_right:
p = &(*p)->rb_right;
}
rb_link_node(&key->node, parent, p);
rb_insert_color(&key->node, &nfs_fscache_keys);
spin_unlock(&nfs_fscache_keys_lock);
nfss->fscache_key = key;
/* create a cache index for looking up filehandles */
nfss->fscache = fscache_acquire_cookie(nfss->nfs_client->fscache,
&nfs_fscache_super_index_def,
nfss);
dfprintk(FSCACHE, "NFS: get superblock cookie (0x%p/0x%p)\n",
nfss, nfss->fscache);
return;
non_unique:
spin_unlock(&nfs_fscache_keys_lock);
kfree(key);
nfss->fscache_key = NULL;
nfss->fscache = NULL;
printk(KERN_WARNING "NFS:"
" Cache request denied due to non-unique superblock keys\n");
}
/*
* release a per-superblock cookie
*/
void nfs_fscache_release_super_cookie(struct super_block *sb)
{
struct nfs_server *nfss = NFS_SB(sb);
dfprintk(FSCACHE, "NFS: releasing superblock cookie (0x%p/0x%p)\n",
nfss, nfss->fscache);
fscache_relinquish_cookie(nfss->fscache, 0);
nfss->fscache = NULL;
if (nfss->fscache_key) {
spin_lock(&nfs_fscache_keys_lock);
rb_erase(&nfss->fscache_key->node, &nfs_fscache_keys);
spin_unlock(&nfs_fscache_keys_lock);
kfree(nfss->fscache_key);
nfss->fscache_key = NULL;
}
}

49
fs/nfs/fscache.h
View File

@ -19,11 +19,49 @@
#ifdef CONFIG_NFS_FSCACHE
/*
* set of NFS FS-Cache objects that form a superblock key
*/
struct nfs_fscache_key {
struct rb_node node;
struct nfs_client *nfs_client; /* the server */
/* the elements of the unique key - as used by nfs_compare_super() and
* nfs_compare_mount_options() to distinguish superblocks */
struct {
struct {
unsigned long s_flags; /* various flags
* (& NFS_MS_MASK) */
} super;
struct {
struct nfs_fsid fsid;
int flags;
unsigned int rsize; /* read size */
unsigned int wsize; /* write size */
unsigned int acregmin; /* attr cache timeouts */
unsigned int acregmax;
unsigned int acdirmin;
unsigned int acdirmax;
} nfs_server;
struct {
rpc_authflavor_t au_flavor;
} rpc_auth;
/* uniquifier - can be used if nfs_server.flags includes
* NFS_MOUNT_UNSHARED */
u8 uniq_len;
char uniquifier[0];
} key;
};
/*
* fscache-index.c
*/
extern struct fscache_netfs nfs_fscache_netfs;
extern const struct fscache_cookie_def nfs_fscache_server_index_def;
extern const struct fscache_cookie_def nfs_fscache_super_index_def;
extern int nfs_fscache_register(void);
extern void nfs_fscache_unregister(void);
@ -34,6 +72,10 @@ extern void nfs_fscache_unregister(void);
extern void nfs_fscache_get_client_cookie(struct nfs_client *);
extern void nfs_fscache_release_client_cookie(struct nfs_client *);
extern void nfs_fscache_get_super_cookie(struct super_block *,
struct nfs_parsed_mount_data *);
extern void nfs_fscache_release_super_cookie(struct super_block *);
#else /* CONFIG_NFS_FSCACHE */
static inline int nfs_fscache_register(void) { return 0; }
static inline void nfs_fscache_unregister(void) {}
@ -41,5 +83,12 @@ static inline void nfs_fscache_unregister(void) {}
static inline void nfs_fscache_get_client_cookie(struct nfs_client *clp) {}
static inline void nfs_fscache_release_client_cookie(struct nfs_client *clp) {}
static inline void nfs_fscache_get_super_cookie(
struct super_block *sb,
struct nfs_parsed_mount_data *data)
{
}
static inline void nfs_fscache_release_super_cookie(struct super_block *sb) {}
#endif /* CONFIG_NFS_FSCACHE */
#endif /* _NFS_FSCACHE_H */

3
fs/nfs/internal.h
View File

@ -5,6 +5,8 @@
#include <linux/mount.h>
#include <linux/security.h>
#define NFS_MS_MASK (MS_RDONLY|MS_NOSUID|MS_NODEV|MS_NOEXEC|MS_SYNCHRONOUS)
struct nfs_string;
/* Maximum number of readahead requests
@ -41,6 +43,7 @@ struct nfs_parsed_mount_data {
unsigned int auth_flavor_len;
rpc_authflavor_t auth_flavors[1];
char *client_address;
char *fscache_uniq;
struct {
struct sockaddr_storage address;

9
fs/nfs/super.c
View File

@ -60,6 +60,7 @@
#include "delegation.h"
#include "iostat.h"
#include "internal.h"
#include "fscache.h"
#define NFSDBG_FACILITY NFSDBG_VFS
@ -1870,8 +1871,6 @@ static void nfs_clone_super(struct super_block *sb,
nfs_initialise_sb(sb);
}
#define NFS_MS_MASK (MS_RDONLY|MS_NOSUID|MS_NODEV|MS_NOEXEC|MS_SYNCHRONOUS)
static int nfs_compare_mount_options(const struct super_block *s, const struct nfs_server *b, int flags)
{
const struct nfs_server *a = s->s_fs_info;
@ -2036,6 +2035,7 @@ static int nfs_get_sb(struct file_system_type *fs_type,
if (!s->s_root) {
/* initial superblock/root creation */
nfs_fill_super(s, data);
nfs_fscache_get_super_cookie(s, data);
}
mntroot = nfs_get_root(s, mntfh);
@ -2056,6 +2056,7 @@ static int nfs_get_sb(struct file_system_type *fs_type,
out:
kfree(data->nfs_server.hostname);
kfree(data->mount_server.hostname);
kfree(data->fscache_uniq);
security_free_mnt_opts(&data->lsm_opts);
out_free_fh:
kfree(mntfh);
@ -2083,6 +2084,7 @@ static void nfs_kill_super(struct super_block *s)
bdi_unregister(&server->backing_dev_info);
kill_anon_super(s);
nfs_fscache_release_super_cookie(s);
nfs_free_server(server);
}
@ -2390,6 +2392,7 @@ static int nfs4_get_sb(struct file_system_type *fs_type,
if (!s->s_root) {
/* initial superblock/root creation */
nfs4_fill_super(s);
nfs_fscache_get_super_cookie(s, data);
}
mntroot = nfs4_get_root(s, mntfh);
@ -2411,6 +2414,7 @@ out:
kfree(data->client_address);
kfree(data->nfs_server.export_path);
kfree(data->nfs_server.hostname);
kfree(data->fscache_uniq);
security_free_mnt_opts(&data->lsm_opts);
out_free_fh:
kfree(mntfh);
@ -2437,6 +2441,7 @@ static void nfs4_kill_super(struct super_block *sb)
kill_anon_super(sb);
nfs4_renewd_prepare_shutdown(server);
nfs_fscache_release_super_cookie(sb);
nfs_free_server(server);
}

5
include/linux/nfs_fs_sb.h
View File

@ -108,6 +108,11 @@ struct nfs_server {
unsigned long mount_time; /* when this fs was mounted */
dev_t s_dev; /* superblock dev numbers */
#ifdef CONFIG_NFS_FSCACHE
struct nfs_fscache_key *fscache_key; /* unique key for superblock */
struct fscache_cookie *fscache; /* superblock cookie */
#endif
#ifdef CONFIG_NFS_V4
u32 attr_bitmask[2];/* V4 bitmask representing the set
of attributes supported on this