From 37ab636880cbc95ba87a5790bee23a1c813089c6 Mon Sep 17 00:00:00 2001 From: David Howells Date: Fri, 6 Apr 2018 14:17:23 +0100 Subject: 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 --- fs/afs/proc.c | 35 ++++++++++++++++++++++++++++++++++- 1 file changed, 34 insertions(+), 1 deletion(-) (limited to 'fs/afs/proc.c') diff --git a/fs/afs/proc.c b/fs/afs/proc.c index 15650cd59404..76f6df32cde0 100644 --- a/fs/afs/proc.c +++ b/fs/afs/proc.c @@ -334,7 +334,40 @@ inval: static ssize_t afs_proc_rootcell_read(struct file *file, char __user *buf, size_t size, loff_t *_pos) { - return 0; + struct afs_cell *cell; + struct afs_net *net = afs_proc2net(file); + unsigned int seq = 0; + char name[AFS_MAXCELLNAME + 1]; + int len; + + if (*_pos > 0) + return 0; + if (!net->ws_cell) + return 0; + + rcu_read_lock(); + do { + read_seqbegin_or_lock(&net->cells_lock, &seq); + len = 0; + cell = rcu_dereference_raw(net->ws_cell); + if (cell) { + len = cell->name_len; + memcpy(name, cell->name, len); + } + } while (need_seqretry(&net->cells_lock, seq)); + done_seqretry(&net->cells_lock, seq); + rcu_read_unlock(); + + if (!len) + return 0; + + name[len++] = '\n'; + if (len > size) + len = size; + if (copy_to_user(buf, name, len) != 0) + return -EFAULT; + *_pos = 1; + return len; } /* -- cgit v1.2.3-70-g09d2