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authorDavid Howells <dhowells@redhat.com>2018-04-06 16:17:23 +0300
committerDavid Howells <dhowells@redhat.com>2018-04-09 23:18:58 +0300
commit37ab636880cbc95ba87a5790bee23a1c813089c6 (patch)
tree931c5387eeefbab0b326b62532644dd6a32c78f0 /fs/afs/dir.c
parent6f8880d8e68155726a2a22e8787cfebf1ffcab08 (diff)
downloadlinux-37ab636880cbc95ba87a5790bee23a1c813089c6.tar.xz
afs: Implement @cell substitution handling
Implement @cell substitution handling such that if @cell is seen as a name in a dynamic root mount, then the name of the root cell for that network namespace will be substituted for @cell during lookup. The substitution of @cell for the current net namespace is set by writing the cell name to /proc/fs/afs/rootcell. The value can be obtained by reading the file. For example: # mount -t afs none /kafs -o dyn # echo grand.central.org >/proc/fs/afs/rootcell # ls /kafs/@cell archive/ cvs/ doc/ local/ project/ service/ software/ user/ www/ # cat /proc/fs/afs/rootcell grand.central.org Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'fs/afs/dir.c')
-rw-r--r--fs/afs/dir.c53
1 files changed, 53 insertions, 0 deletions
diff --git a/fs/afs/dir.c b/fs/afs/dir.c
index 3ebd741b74d0..b073976db8d2 100644
--- a/fs/afs/dir.c
+++ b/fs/afs/dir.c
@@ -909,6 +909,55 @@ success:
}
/*
+ * Look up @cell in a dynroot directory. This is a substitution for the
+ * local cell name for the net namespace.
+ */
+static struct dentry *afs_lookup_atcell(struct dentry *dentry)
+{
+ struct afs_cell *cell;
+ struct afs_net *net = afs_d2net(dentry);
+ struct dentry *ret;
+ unsigned int seq = 0;
+ char *name;
+ int len;
+
+ if (!net->ws_cell)
+ return ERR_PTR(-ENOENT);
+
+ ret = ERR_PTR(-ENOMEM);
+ name = kmalloc(AFS_MAXCELLNAME + 1, GFP_KERNEL);
+ if (!name)
+ goto out_p;
+
+ rcu_read_lock();
+ do {
+ read_seqbegin_or_lock(&net->cells_lock, &seq);
+ cell = rcu_dereference_raw(net->ws_cell);
+ if (cell) {
+ len = cell->name_len;
+ memcpy(name, cell->name, len + 1);
+ }
+ } while (need_seqretry(&net->cells_lock, seq));
+ done_seqretry(&net->cells_lock, seq);
+ rcu_read_unlock();
+
+ ret = ERR_PTR(-ENOENT);
+ if (!cell)
+ goto out_n;
+
+ ret = lookup_one_len(name, dentry->d_parent, len);
+
+ /* We don't want to d_add() the @cell dentry here as we don't want to
+ * the cached dentry to hide changes to the local cell name.
+ */
+
+out_n:
+ kfree(name);
+out_p:
+ return ret;
+}
+
+/*
* Look up an entry in a dynroot directory.
*/
static struct dentry *afs_dynroot_lookup(struct inode *dir, struct dentry *dentry,
@@ -929,6 +978,10 @@ static struct dentry *afs_dynroot_lookup(struct inode *dir, struct dentry *dentr
return ERR_PTR(-ENAMETOOLONG);
}
+ if (dentry->d_name.len == 5 &&
+ memcmp(dentry->d_name.name, "@cell", 5) == 0)
+ return afs_lookup_atcell(dentry);
+
inode = afs_try_auto_mntpt(dentry, dir);
if (IS_ERR(inode)) {
ret = PTR_ERR(inode);