AFS: Implement an autocell mount capability [ver #2]
Implement the ability for the root directory of a mounted AFS filesystem to
accept lookups of arbitrary directory names, to interpet the names as the names
of cells, to look the cell names up in the DNS for AFSDB records and to mount
the root.cell volume of the nominated cell on the pseudo-directory created by
lookup.
This facility is requested by passing:
-o autocell
to the mountpoint for which this is desired, usually the /afs mount.
To use this facility, a DNS upcall program is required for AFSDB records. This
can be obtained from:
http://people.redhat.com/~dhowells/afs/dns.afsdb.c
It should be compiled with -lresolv and -lkeyutils and installed as, say:
/usr/sbin/dns.afsdb
Then the following line needs to be added to /sbin/request-key.conf:
create dns_resolver afsdb:* * /usr/sbin/dns.afsdb %k
This can be tested by mounting AFS, say:
insmod dns_resolver.ko
insmod af-rxrpc.ko
insmod kafs.ko rootcell=grand.central.org
mount -t afs "#grand.central.org:root.cell." /afs -o autocell
and doing:
ls /afs/grand.central.org/
which should show:
archive/ cvs/ doc/ local/ project/ service/ software/ user/ www/
if it works.
Signed-off-by: Wang Lei <wang840925@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/afs/cell.c b/fs/afs/cell.c
index d076588..0d5eeadf 100644
--- a/fs/afs/cell.c
+++ b/fs/afs/cell.c
@@ -31,21 +31,20 @@
* allocate a cell record and fill in its name, VL server address list and
* allocate an anonymous key
*/
-static struct afs_cell *afs_cell_alloc(const char *name, char *vllist)
+static struct afs_cell *afs_cell_alloc(const char *name, unsigned namelen,
+ char *vllist)
{
struct afs_cell *cell;
struct key *key;
- size_t namelen;
char keyname[4 + AFS_MAXCELLNAME + 1], *cp, *dp, *next;
char *dvllist = NULL, *_vllist = NULL;
char delimiter = ':';
int ret;
- _enter("%s,%s", name, vllist);
+ _enter("%*.*s,%s", namelen, namelen, name ?: "", vllist);
BUG_ON(!name); /* TODO: want to look up "this cell" in the cache */
- namelen = strlen(name);
if (namelen > AFS_MAXCELLNAME) {
_leave(" = -ENAMETOOLONG");
return ERR_PTR(-ENAMETOOLONG);
@@ -142,26 +141,29 @@
}
/*
- * create a cell record
- * - "name" is the name of the cell
- * - "vllist" is a colon separated list of IP addresses in "a.b.c.d" format
+ * afs_cell_crate() - create a cell record
+ * @name: is the name of the cell.
+ * @namsesz: is the strlen of the cell name.
+ * @vllist: is a colon separated list of IP addresses in "a.b.c.d" format.
+ * @retref: is T to return the cell reference when the cell exists.
*/
-struct afs_cell *afs_cell_create(const char *name, char *vllist)
+struct afs_cell *afs_cell_create(const char *name, unsigned namesz,
+ char *vllist, bool retref)
{
struct afs_cell *cell;
int ret;
- _enter("%s,%s", name, vllist);
+ _enter("%*.*s,%s", namesz, namesz, name ?: "", vllist);
down_write(&afs_cells_sem);
read_lock(&afs_cells_lock);
list_for_each_entry(cell, &afs_cells, link) {
- if (strcasecmp(cell->name, name) == 0)
+ if (strncasecmp(cell->name, name, namesz) == 0)
goto duplicate_name;
}
read_unlock(&afs_cells_lock);
- cell = afs_cell_alloc(name, vllist);
+ cell = afs_cell_alloc(name, namesz, vllist);
if (IS_ERR(cell)) {
_leave(" = %ld", PTR_ERR(cell));
up_write(&afs_cells_sem);
@@ -201,8 +203,18 @@
return ERR_PTR(ret);
duplicate_name:
+ if (retref && !IS_ERR(cell))
+ afs_get_cell(cell);
+
read_unlock(&afs_cells_lock);
up_write(&afs_cells_sem);
+
+ if (retref) {
+ _leave(" = %p", cell);
+ return cell;
+ }
+
+ _leave(" = -EEXIST");
return ERR_PTR(-EEXIST);
}
@@ -233,7 +245,7 @@
*cp++ = 0;
/* allocate a cell record for the root cell */
- new_root = afs_cell_create(rootcell, cp);
+ new_root = afs_cell_create(rootcell, strlen(rootcell), cp, false);
if (IS_ERR(new_root)) {
_leave(" = %ld", PTR_ERR(new_root));
return PTR_ERR(new_root);
@@ -253,11 +265,12 @@
/*
* lookup a cell record
*/
-struct afs_cell *afs_cell_lookup(const char *name, unsigned namesz)
+struct afs_cell *afs_cell_lookup(const char *name, unsigned namesz,
+ bool dns_cell)
{
struct afs_cell *cell;
- _enter("\"%*.*s\",", namesz, namesz, name ? name : "");
+ _enter("\"%*.*s\",", namesz, namesz, name ?: "");
down_read(&afs_cells_sem);
read_lock(&afs_cells_lock);
@@ -271,6 +284,8 @@
}
}
cell = ERR_PTR(-ENOENT);
+ if (dns_cell)
+ goto create_cell;
found:
;
} else {
@@ -293,6 +308,15 @@
up_read(&afs_cells_sem);
_leave(" = %p", cell);
return cell;
+
+create_cell:
+ read_unlock(&afs_cells_lock);
+ up_read(&afs_cells_sem);
+
+ cell = afs_cell_create(name, namesz, NULL, true);
+
+ _leave(" = %p", cell);
+ return cell;
}
#if 0
diff --git a/fs/afs/dir.c b/fs/afs/dir.c
index b42d5cc..0d38c09 100644
--- a/fs/afs/dir.c
+++ b/fs/afs/dir.c
@@ -477,6 +477,40 @@
}
/*
+ * Try to auto mount the mountpoint with pseudo directory, if the autocell
+ * operation is setted.
+ */
+static struct inode *afs_try_auto_mntpt(
+ int ret, struct dentry *dentry, struct inode *dir, struct key *key,
+ struct afs_fid *fid)
+{
+ const char *devname = dentry->d_name.name;
+ struct afs_vnode *vnode = AFS_FS_I(dir);
+ struct inode *inode;
+
+ _enter("%d, %p{%s}, {%x:%u}, %p",
+ ret, dentry, devname, vnode->fid.vid, vnode->fid.vnode, key);
+
+ if (ret != -ENOENT ||
+ !test_bit(AFS_VNODE_AUTOCELL, &vnode->flags))
+ goto out;
+
+ inode = afs_iget_autocell(dir, devname, strlen(devname), key);
+ if (IS_ERR(inode)) {
+ ret = PTR_ERR(inode);
+ goto out;
+ }
+
+ *fid = AFS_FS_I(inode)->fid;
+ _leave("= %p", inode);
+ return inode;
+
+out:
+ _leave("= %d", ret);
+ return ERR_PTR(ret);
+}
+
+/*
* look up an entry in a directory
*/
static struct dentry *afs_lookup(struct inode *dir, struct dentry *dentry,
@@ -520,6 +554,13 @@
ret = afs_do_lookup(dir, dentry, &fid, key);
if (ret < 0) {
+ inode = afs_try_auto_mntpt(ret, dentry, dir, key, &fid);
+ if (!IS_ERR(inode)) {
+ key_put(key);
+ goto success;
+ }
+
+ ret = PTR_ERR(inode);
key_put(key);
if (ret == -ENOENT) {
d_add(dentry, NULL);
@@ -539,6 +580,7 @@
return ERR_CAST(inode);
}
+success:
dentry->d_op = &afs_fs_dentry_operations;
d_add(dentry, inode);
@@ -696,8 +738,9 @@
goto zap;
if (dentry->d_inode &&
- test_bit(AFS_VNODE_DELETED, &AFS_FS_I(dentry->d_inode)->flags))
- goto zap;
+ (test_bit(AFS_VNODE_DELETED, &AFS_FS_I(dentry->d_inode)->flags) ||
+ test_bit(AFS_VNODE_PSEUDODIR, &AFS_FS_I(dentry->d_inode)->flags)))
+ goto zap;
_leave(" = 0 [keep]");
return 0;
diff --git a/fs/afs/inode.c b/fs/afs/inode.c
index 320ffef..0747339 100644
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -19,6 +19,8 @@
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/sched.h>
+#include <linux/mount.h>
+#include <linux/namei.h>
#include "internal.h"
struct afs_iget_data {
@@ -102,6 +104,16 @@
}
/*
+ * iget5() comparator for inode created by autocell operations
+ *
+ * These pseudo inodes don't match anything.
+ */
+static int afs_iget5_autocell_test(struct inode *inode, void *opaque)
+{
+ return 0;
+}
+
+/*
* iget5() inode initialiser
*/
static int afs_iget5_set(struct inode *inode, void *opaque)
@@ -118,6 +130,67 @@
}
/*
+ * inode retrieval for autocell
+ */
+struct inode *afs_iget_autocell(struct inode *dir, const char *dev_name,
+ int namesz, struct key *key)
+{
+ struct afs_iget_data data;
+ struct afs_super_info *as;
+ struct afs_vnode *vnode;
+ struct super_block *sb;
+ struct inode *inode;
+ static atomic_t afs_autocell_ino;
+
+ _enter("{%x:%u},%*.*s,",
+ AFS_FS_I(dir)->fid.vid, AFS_FS_I(dir)->fid.vnode,
+ namesz, namesz, dev_name ?: "");
+
+ sb = dir->i_sb;
+ as = sb->s_fs_info;
+ data.volume = as->volume;
+ data.fid.vid = as->volume->vid;
+ data.fid.unique = 0;
+ data.fid.vnode = 0;
+
+ inode = iget5_locked(sb, atomic_inc_return(&afs_autocell_ino),
+ afs_iget5_autocell_test, afs_iget5_set,
+ &data);
+ if (!inode) {
+ _leave(" = -ENOMEM");
+ return ERR_PTR(-ENOMEM);
+ }
+
+ _debug("GOT INODE %p { ino=%lu, vl=%x, vn=%x, u=%x }",
+ inode, inode->i_ino, data.fid.vid, data.fid.vnode,
+ data.fid.unique);
+
+ vnode = AFS_FS_I(inode);
+
+ /* there shouldn't be an existing inode */
+ BUG_ON(!(inode->i_state & I_NEW));
+
+ inode->i_size = 0;
+ inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO;
+ inode->i_op = &afs_autocell_inode_operations;
+ inode->i_nlink = 2;
+ inode->i_uid = 0;
+ inode->i_gid = 0;
+ inode->i_ctime.tv_sec = get_seconds();
+ inode->i_ctime.tv_nsec = 0;
+ inode->i_atime = inode->i_mtime = inode->i_ctime;
+ inode->i_blocks = 0;
+ inode->i_version = 0;
+ inode->i_generation = 0;
+
+ set_bit(AFS_VNODE_PSEUDODIR, &vnode->flags);
+ inode->i_flags |= S_NOATIME;
+ unlock_new_inode(inode);
+ _leave(" = %p", inode);
+ return inode;
+}
+
+/*
* inode retrieval
*/
struct inode *afs_iget(struct super_block *sb, struct key *key,
@@ -314,6 +387,19 @@
}
/*
+ * discard an AFS inode
+ */
+int afs_drop_inode(struct inode *inode)
+{
+ _enter("");
+
+ if (test_bit(AFS_VNODE_PSEUDODIR, &AFS_FS_I(inode)->flags))
+ return generic_delete_inode(inode);
+ else
+ return generic_drop_inode(inode);
+}
+
+/*
* clear an AFS inode
*/
void afs_evict_inode(struct inode *inode)
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 8679089..ce12a2b 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -42,6 +42,7 @@
struct afs_mount_params {
bool rwpath; /* T if the parent should be considered R/W */
bool force; /* T to force cell type */
+ bool autocell; /* T if set auto mount operation */
afs_voltype_t type; /* type of volume requested */
int volnamesz; /* size of volume name */
const char *volname; /* name of volume to mount */
@@ -358,6 +359,8 @@
#define AFS_VNODE_READLOCKED 7 /* set if vnode is read-locked on the server */
#define AFS_VNODE_WRITELOCKED 8 /* set if vnode is write-locked on the server */
#define AFS_VNODE_UNLOCKING 9 /* set if vnode is being unlocked on the server */
+#define AFS_VNODE_AUTOCELL 10 /* set if Vnode is an auto mount point */
+#define AFS_VNODE_PSEUDODIR 11 /* set if Vnode is a pseudo directory */
long acl_order; /* ACL check count (callback break count) */
@@ -468,8 +471,8 @@
#define afs_get_cell(C) do { atomic_inc(&(C)->usage); } while(0)
extern int afs_cell_init(char *);
-extern struct afs_cell *afs_cell_create(const char *, char *);
-extern struct afs_cell *afs_cell_lookup(const char *, unsigned);
+extern struct afs_cell *afs_cell_create(const char *, unsigned, char *, bool);
+extern struct afs_cell *afs_cell_lookup(const char *, unsigned, bool);
extern struct afs_cell *afs_grab_cell(struct afs_cell *);
extern void afs_put_cell(struct afs_cell *);
extern void afs_cell_purge(void);
@@ -558,6 +561,8 @@
/*
* inode.c
*/
+extern struct inode *afs_iget_autocell(struct inode *, const char *, int,
+ struct key *);
extern struct inode *afs_iget(struct super_block *, struct key *,
struct afs_fid *, struct afs_file_status *,
struct afs_callback *);
@@ -566,6 +571,7 @@
extern int afs_getattr(struct vfsmount *, struct dentry *, struct kstat *);
extern int afs_setattr(struct dentry *, struct iattr *);
extern void afs_evict_inode(struct inode *);
+extern int afs_drop_inode(struct inode *);
/*
* main.c
@@ -581,6 +587,7 @@
* mntpt.c
*/
extern const struct inode_operations afs_mntpt_inode_operations;
+extern const struct inode_operations afs_autocell_inode_operations;
extern const struct file_operations afs_mntpt_file_operations;
extern int afs_mntpt_check_symlink(struct afs_vnode *, struct key *);
diff --git a/fs/afs/mntpt.c b/fs/afs/mntpt.c
index a9e2303..6d55268 100644
--- a/fs/afs/mntpt.c
+++ b/fs/afs/mntpt.c
@@ -38,6 +38,11 @@
.getattr = afs_getattr,
};
+const struct inode_operations afs_autocell_inode_operations = {
+ .follow_link = afs_mntpt_follow_link,
+ .getattr = afs_getattr,
+};
+
static LIST_HEAD(afs_vfsmounts);
static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out);
@@ -136,20 +141,16 @@
{
struct afs_super_info *super;
struct vfsmount *mnt;
+ struct afs_vnode *vnode;
struct page *page;
- size_t size;
- char *buf, *devname, *options;
+ char *devname, *options;
+ bool rwpath = false;
int ret;
_enter("{%s}", mntpt->d_name.name);
BUG_ON(!mntpt->d_inode);
- ret = -EINVAL;
- size = mntpt->d_inode->i_size;
- if (size > PAGE_SIZE - 1)
- goto error_no_devname;
-
ret = -ENOMEM;
devname = (char *) get_zeroed_page(GFP_KERNEL);
if (!devname)
@@ -159,28 +160,59 @@
if (!options)
goto error_no_options;
- /* read the contents of the AFS special symlink */
- page = read_mapping_page(mntpt->d_inode->i_mapping, 0, NULL);
- if (IS_ERR(page)) {
- ret = PTR_ERR(page);
- goto error_no_page;
+ vnode = AFS_FS_I(mntpt->d_inode);
+ if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) {
+ /* if the directory is a pseudo directory, use the d_name */
+ static const char afs_root_cell[] = ":root.cell.";
+ unsigned size = mntpt->d_name.len;
+
+ ret = -ENOENT;
+ if (size < 2 || size > AFS_MAXCELLNAME)
+ goto error_no_page;
+
+ if (mntpt->d_name.name[0] == '.') {
+ devname[0] = '#';
+ memcpy(devname + 1, mntpt->d_name.name, size - 1);
+ memcpy(devname + size, afs_root_cell,
+ sizeof(afs_root_cell));
+ rwpath = true;
+ } else {
+ devname[0] = '%';
+ memcpy(devname + 1, mntpt->d_name.name, size);
+ memcpy(devname + size + 1, afs_root_cell,
+ sizeof(afs_root_cell));
+ }
+ } else {
+ /* read the contents of the AFS special symlink */
+ loff_t size = i_size_read(mntpt->d_inode);
+ char *buf;
+
+ ret = -EINVAL;
+ if (size > PAGE_SIZE - 1)
+ goto error_no_page;
+
+ page = read_mapping_page(mntpt->d_inode->i_mapping, 0, NULL);
+ if (IS_ERR(page)) {
+ ret = PTR_ERR(page);
+ goto error_no_page;
+ }
+
+ ret = -EIO;
+ if (PageError(page))
+ goto error;
+
+ buf = kmap_atomic(page, KM_USER0);
+ memcpy(devname, buf, size);
+ kunmap_atomic(buf, KM_USER0);
+ page_cache_release(page);
+ page = NULL;
}
- ret = -EIO;
- if (PageError(page))
- goto error;
-
- buf = kmap_atomic(page, KM_USER0);
- memcpy(devname, buf, size);
- kunmap_atomic(buf, KM_USER0);
- page_cache_release(page);
- page = NULL;
-
/* work out what options we want */
super = AFS_FS_S(mntpt->d_sb);
memcpy(options, "cell=", 5);
strcpy(options + 5, super->volume->cell->name);
- if (super->volume->type == AFSVL_RWVOL)
+ if (super->volume->type == AFSVL_RWVOL || rwpath)
strcat(options, ",rwpath");
/* try and do the mount */
diff --git a/fs/afs/proc.c b/fs/afs/proc.c
index 852739d..096b23f 100644
--- a/fs/afs/proc.c
+++ b/fs/afs/proc.c
@@ -294,7 +294,7 @@
if (strcmp(kbuf, "add") == 0) {
struct afs_cell *cell;
- cell = afs_cell_create(name, args);
+ cell = afs_cell_create(name, strlen(name), args, false);
if (IS_ERR(cell)) {
ret = PTR_ERR(cell);
goto done;
diff --git a/fs/afs/super.c b/fs/afs/super.c
index 9cf80f0..77e1e5a 100644
--- a/fs/afs/super.c
+++ b/fs/afs/super.c
@@ -16,6 +16,7 @@
#include <linux/kernel.h>
#include <linux/module.h>
+#include <linux/mount.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/smp_lock.h>
@@ -48,6 +49,7 @@
static const struct super_operations afs_super_ops = {
.statfs = afs_statfs,
.alloc_inode = afs_alloc_inode,
+ .drop_inode = afs_drop_inode,
.destroy_inode = afs_destroy_inode,
.evict_inode = afs_evict_inode,
.put_super = afs_put_super,
@@ -62,12 +64,14 @@
afs_opt_cell,
afs_opt_rwpath,
afs_opt_vol,
+ afs_opt_autocell,
};
static const match_table_t afs_options_list = {
{ afs_opt_cell, "cell=%s" },
{ afs_opt_rwpath, "rwpath" },
{ afs_opt_vol, "vol=%s" },
+ { afs_opt_autocell, "autocell" },
{ afs_no_opt, NULL },
};
@@ -151,7 +155,8 @@
switch (token) {
case afs_opt_cell:
cell = afs_cell_lookup(args[0].from,
- args[0].to - args[0].from);
+ args[0].to - args[0].from,
+ false);
if (IS_ERR(cell))
return PTR_ERR(cell);
afs_put_cell(params->cell);
@@ -166,6 +171,10 @@
*devname = args[0].from;
break;
+ case afs_opt_autocell:
+ params->autocell = 1;
+ break;
+
default:
printk(KERN_ERR "kAFS:"
" Unknown or invalid mount option: '%s'\n", p);
@@ -252,10 +261,10 @@
/* lookup the cell record */
if (cellname || !params->cell) {
- cell = afs_cell_lookup(cellname, cellnamesz);
+ cell = afs_cell_lookup(cellname, cellnamesz, true);
if (IS_ERR(cell)) {
- printk(KERN_ERR "kAFS: unable to lookup cell '%s'\n",
- cellname ?: "");
+ printk(KERN_ERR "kAFS: unable to lookup cell '%*.*s'\n",
+ cellnamesz, cellnamesz, cellname ?: "");
return PTR_ERR(cell);
}
afs_put_cell(params->cell);
@@ -321,6 +330,9 @@
if (IS_ERR(inode))
goto error_inode;
+ if (params->autocell)
+ set_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(inode)->flags);
+
ret = -ENOMEM;
root = d_alloc_root(inode);
if (!root)