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Merge afs RCU pathwalk fix 

Bring in the fix for afs_atcell_get_link() to handle RCU pathwalk from
the afs branch for this cycle. This fix has to go upstream now.

Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner 2025-03-10 11:09:25 +01:00
parent 00a7d39898 823869e1e6
commit accdd1198e
No known key found for this signature in database
GPG Key ID: 91C61BC06578DCA2
4 changed files with 22 additions and 10 deletions
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11
fs/afs/cell.c
View File

@ -64,7 +64,8 @@ static struct afs_cell *afs_find_cell_locked(struct afs_net *net,
return ERR_PTR(-ENAMETOOLONG);
if (!name) {
cell = net->ws_cell;
cell = rcu_dereference_protected(net->ws_cell,
lockdep_is_held(&net->cells_lock));
if (!cell)
return ERR_PTR(-EDESTADDRREQ);
goto found;
@ -388,8 +389,8 @@ int afs_cell_init(struct afs_net *net, const char *rootcell)
/* install the new cell */
down_write(&net->cells_lock);
afs_see_cell(new_root, afs_cell_trace_see_ws);
old_root = net->ws_cell;
net->ws_cell = new_root;
old_root = rcu_replace_pointer(net->ws_cell, new_root,
lockdep_is_held(&net->cells_lock));
up_write(&net->cells_lock);
afs_unuse_cell(net, old_root, afs_cell_trace_unuse_ws);
@ -945,8 +946,8 @@ void afs_cell_purge(struct afs_net *net)
_enter("");
down_write(&net->cells_lock);
ws = net->ws_cell;
net->ws_cell = NULL;
ws = rcu_replace_pointer(net->ws_cell, NULL,
lockdep_is_held(&net->cells_lock));
up_write(&net->cells_lock);
afs_unuse_cell(net, ws, afs_cell_trace_unuse_ws);

15
fs/afs/dynroot.c
View File

@ -314,12 +314,23 @@ static const char *afs_atcell_get_link(struct dentry *dentry, struct inode *inod
const char *name;
bool dotted = vnode->fid.vnode == 3;
if (!net->ws_cell)
if (!dentry) {
/* We're in RCU-pathwalk. */
cell = rcu_dereference(net->ws_cell);
if (dotted)
name = cell->name - 1;
else
name = cell->name;
/* Shouldn't need to set a delayed call. */
return name;
}
if (!rcu_access_pointer(net->ws_cell))
return ERR_PTR(-ENOENT);
down_read(&net->cells_lock);
cell = net->ws_cell;
cell = rcu_dereference_protected(net->ws_cell, lockdep_is_held(&net->cells_lock));
if (dotted)
name = cell->name - 1;
else

2
fs/afs/internal.h
View File

@ -287,7 +287,7 @@ struct afs_net {
/* Cell database */
struct rb_root cells;
struct afs_cell *ws_cell;
struct afs_cell __rcu *ws_cell;
struct work_struct cells_manager;
struct timer_list cells_timer;
atomic_t cells_outstanding;

4
fs/afs/proc.c
View File

@ -206,7 +206,7 @@ static int afs_proc_rootcell_show(struct seq_file *m, void *v)
net = afs_seq2net_single(m);
down_read(&net->cells_lock);
cell = net->ws_cell;
cell = rcu_dereference_protected(net->ws_cell, lockdep_is_held(&net->cells_lock));
if (cell)
seq_printf(m, "%s\n", cell->name);
up_read(&net->cells_lock);
@ -242,7 +242,7 @@ static int afs_proc_rootcell_write(struct file *file, char *buf, size_t size)
ret = -EEXIST;
inode_lock(file_inode(file));
if (!net->ws_cell)
if (!rcu_access_pointer(net->ws_cell))
ret = afs_cell_init(net, buf);
else
printk("busy\n");