[PATCH v4 32/54] convert binfmt_misc

Al Viro
2025-11-18T05:16:10Z

removals are done with locked_recursive_removal(); switch creations to
simple_start_creating()/d_make_persistent()/simple_done_creating() and
take them to a helper (add_entry()), while we are at it - simpler control
flow that way.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/binfmt_misc.c | 69 ++++++++++++++++++++++--------------------------
1 file changed, 32 insertions(+), 37 deletions(-)

diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c
index a839f960cd4a..2093f9dcd321 100644
--- a/fs/binfmt_misc.c
+++ b/fs/binfmt_misc.c
@@ -765,14 +765,41 @@ static const struct file_operations bm_entry_operations = {

/* /register */

+/* add to filesystem */
+static int add_entry(Node *e, struct super_block *sb)
+{
+ struct dentry *dentry = simple_start_creating(sb->s_root, e->name);
+ struct inode *inode;
+ struct binfmt_misc *misc;
+
+ if (IS_ERR(dentry))
+ return PTR_ERR(dentry);
+
+ inode = bm_get_inode(sb, S_IFREG | 0644);
+ if (unlikely(!inode)) {
+ simple_done_creating(dentry);
+ return -ENOMEM;
+ }
+
+ refcount_set(&e->users, 1);
+ e->dentry = dentry;
+ inode->i_private = e;
+ inode->i_fop = &bm_entry_operations;
+
+ d_make_persistent(dentry, inode);
+ misc = i_binfmt_misc(inode);
+ write_lock(&misc->entries_lock);
+ list_add(&e->list, &misc->entries);
+ write_unlock(&misc->entries_lock);
+ simple_done_creating(dentry);
+ return 0;
+}
+
static ssize_t bm_register_write(struct file *file, const char __user *buffer,
size_t count, loff_t *ppos)
{
Node *e;
- struct inode *inode;
struct super_block *sb = file_inode(file)->i_sb;
- struct dentry *root = sb->s_root, *dentry;
- struct binfmt_misc *misc;
int err = 0;
struct file *f = NULL;

@@ -803,39 +830,7 @@ static ssize_t bm_register_write(struct file *file, const char __user *buffer,
e->interp_file = f;
}

- inode_lock(d_inode(root));
- dentry = lookup_noperm(&QSTR(e->name), root);
- err = PTR_ERR(dentry);
- if (IS_ERR(dentry))
- goto out;
-
- err = -EEXIST;
- if (d_really_is_positive(dentry))
- goto out2;
-
- inode = bm_get_inode(sb, S_IFREG | 0644);
-
- err = -ENOMEM;
- if (!inode)
- goto out2;
-
- refcount_set(&e->users, 1);
- e->dentry = dget(dentry);
- inode->i_private = e;
- inode->i_fop = &bm_entry_operations;
-
- d_instantiate(dentry, inode);
- misc = i_binfmt_misc(inode);
- write_lock(&misc->entries_lock);
- list_add(&e->list, &misc->entries);
- write_unlock(&misc->entries_lock);
-
- err = 0;
-out2:
- dput(dentry);
-out:
- inode_unlock(d_inode(root));
-
+ err = add_entry(e, sb);
if (err) {
if (f)
filp_close(f, NULL);
@@ -1028,7 +1023,7 @@ static struct file_system_type bm_fs_type = {
.name = "binfmt_misc",
.init_fs_context = bm_init_fs_context,
.fs_flags = FS_USERNS_MOUNT,
- .kill_sb = kill_litter_super,
+ .kill_sb = kill_anon_super,
};
MODULE_ALIAS_FS("binfmt_misc");

--
2.47.3