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authorwanglei <wang840925@gmail.com>2010-08-11 12:38:04 +0400
committerSteve French <sfrench@us.ibm.com>2010-08-11 21:11:29 +0400
commitbec5eb6141308a30a73682330cb045a40e442b8c (patch)
treeae514575d62e65a07d6089746fbd880f816ee382 /fs/afs/cell.c
parent4a2d789267e00b5a1175ecd2ddefcc78b83fbf09 (diff)
downloadlinux-bec5eb6141308a30a73682330cb045a40e442b8c.tar.xz
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>
Diffstat (limited to 'fs/afs/cell.c')
-rw-r--r--fs/afs/cell.c52
1 files changed, 38 insertions, 14 deletions
diff --git a/fs/afs/cell.c b/fs/afs/cell.c
index d0765883430e..0d5eeadf6121 100644
--- a/fs/afs/cell.c
+++ b/fs/afs/cell.c
@@ -31,21 +31,20 @@ static struct afs_cell *afs_cell_root;
* 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 @@ error:
}
/*
- * 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 @@ error:
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 @@ int afs_cell_init(char *rootcell)
*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 @@ int afs_cell_init(char *rootcell)
/*
* 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 @@ struct afs_cell *afs_cell_lookup(const char *name, unsigned namesz)
}
}
cell = ERR_PTR(-ENOENT);
+ if (dns_cell)
+ goto create_cell;
found:
;
} else {
@@ -293,6 +308,15 @@ struct afs_cell *afs_cell_lookup(const char *name, unsigned namesz)
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