diff options
Diffstat (limited to 'fs/proc/proc_sysctl.c')
| -rw-r--r-- | fs/proc/proc_sysctl.c | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c index fea2561d773b..fdda62e6115e 100644 --- a/fs/proc/proc_sysctl.c +++ b/fs/proc/proc_sysctl.c @@ -19,6 +19,28 @@ static const struct inode_operations proc_sys_inode_operations; static const struct file_operations proc_sys_dir_file_operations; static const struct inode_operations proc_sys_dir_operations; +/* Support for permanently empty directories */ + +struct ctl_table sysctl_mount_point[] = { + { } +}; + +static bool is_empty_dir(struct ctl_table_header *head) +{ + return head->ctl_table[0].child == sysctl_mount_point; +} + +static void set_empty_dir(struct ctl_dir *dir) +{ + dir->header.ctl_table[0].child = sysctl_mount_point; +} + +static void clear_empty_dir(struct ctl_dir *dir) + +{ + dir->header.ctl_table[0].child = NULL; +} + void proc_sys_poll_notify(struct ctl_table_poll *poll) { if (!poll) @@ -187,6 +209,17 @@ static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header) struct ctl_table *entry; int err; + /* Is this a permanently empty directory? */ + if (is_empty_dir(&dir->header)) + return -EROFS; + + /* Am I creating a permanently empty directory? */ + if (header->ctl_table == sysctl_mount_point) { + if (!RB_EMPTY_ROOT(&dir->root)) + return -EINVAL; + set_empty_dir(dir); + } + dir->header.nreg++; header->parent = dir; err = insert_links(header); @@ -202,6 +235,8 @@ fail: erase_header(header); put_links(header); fail_links: + if (header->ctl_table == sysctl_mount_point) + clear_empty_dir(dir); header->parent = NULL; drop_sysctl_table(&dir->header); return err; @@ -419,6 +454,8 @@ static struct inode *proc_sys_make_inode(struct super_block *sb, inode->i_mode |= S_IFDIR; inode->i_op = &proc_sys_dir_operations; inode->i_fop = &proc_sys_dir_file_operations; + if (is_empty_dir(head)) + make_empty_dir_inode(inode); } out: return inode; |