[PATCH v2 01/50] fuse_ctl_add_conn(): fix nlink breakage in case of early failure

Al Viro
2025-10-28T00:46:21Z

fuse_ctl_remove_conn() used to decrement the link count of root
manually; that got subsumed by simple_recursive_removal(), but
in case when subdirectory creation has failed the latter won't
get called.

Just move the modification of parent's link count into
fuse_ctl_add_dentry() to keep the things simple. Allows to
get rid of the nlink argument as well...

Fixes: fcaac5b42768 "fuse_ctl: use simple_recursive_removal()"
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/fuse/control.c | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/fs/fuse/control.c b/fs/fuse/control.c
index bb407705603c..5247df896c5d 100644
--- a/fs/fuse/control.c
+++ b/fs/fuse/control.c
@@ -205,8 +205,7 @@ static const struct file_operations fuse_conn_congestion_threshold_ops = {

static struct dentry *fuse_ctl_add_dentry(struct dentry *parent,
struct fuse_conn *fc,
- const char *name,
- int mode, int nlink,
+ const char *name, int mode,
const struct inode_operations *iop,
const struct file_operations *fop)
{
@@ -232,7 +231,10 @@ static struct dentry *fuse_ctl_add_dentry(struct dentry *parent,
if (iop)
inode->i_op = iop;
inode->i_fop = fop;
- set_nlink(inode, nlink);
+ if (S_ISDIR(mode)) {
+ inc_nlink(d_inode(parent));
+ inc_nlink(inode);
+ }
inode->i_private = fc;
d_add(dentry, inode);

@@ -252,22 +254,21 @@ int fuse_ctl_add_conn(struct fuse_conn *fc)
return 0;

parent = fuse_control_sb->s_root;
- inc_nlink(d_inode(parent));
sprintf(name, "%u", fc->dev);
- parent = fuse_ctl_add_dentry(parent, fc, name, S_IFDIR | 0500, 2,
+ parent = fuse_ctl_add_dentry(parent, fc, name, S_IFDIR | 0500,
&simple_dir_inode_operations,
&simple_dir_operations);
if (!parent)
goto err;

- if (!fuse_ctl_add_dentry(parent, fc, "waiting", S_IFREG | 0400, 1,
+ if (!fuse_ctl_add_dentry(parent, fc, "waiting", S_IFREG | 0400,
NULL, &fuse_ctl_waiting_ops) ||
- !fuse_ctl_add_dentry(parent, fc, "abort", S_IFREG | 0200, 1,
+ !fuse_ctl_add_dentry(parent, fc, "abort", S_IFREG | 0200,
NULL, &fuse_ctl_abort_ops) ||
!fuse_ctl_add_dentry(parent, fc, "max_background", S_IFREG | 0600,
- 1, NULL, &fuse_conn_max_background_ops) ||
+ NULL, &fuse_conn_max_background_ops) ||
!fuse_ctl_add_dentry(parent, fc, "congestion_threshold",
- S_IFREG | 0600, 1, NULL,
+ S_IFREG | 0600, NULL,
&fuse_conn_congestion_threshold_ops))
goto err;

--
2.47.3