diff options
| -rw-r--r-- | fs/ocfs2/stack_user.c | 144 |
1 files changed, 139 insertions, 5 deletions
diff --git a/fs/ocfs2/stack_user.c b/fs/ocfs2/stack_user.c index fdca5d3c7668..ff8d30757924 100644 --- a/fs/ocfs2/stack_user.c +++ b/fs/ocfs2/stack_user.c @@ -22,6 +22,7 @@ #include <linux/miscdevice.h> #include <linux/mutex.h> #include <linux/reboot.h> +#include <asm/uaccess.h> #include "stackglue.h" @@ -40,6 +41,16 @@ */ /* + * Whether or not the client has done the handshake. + * For now, we have just one protocol version. + */ +#define OCFS2_CONTROL_PROTO "T01\n" +#define OCFS2_CONTROL_PROTO_LEN 4 +#define OCFS2_CONTROL_HANDSHAKE_INVALID (0) +#define OCFS2_CONTROL_HANDSHAKE_READ (1) +#define OCFS2_CONTROL_HANDSHAKE_VALID (2) + +/* * ocfs2_live_connection is refcounted because the filesystem and * miscdevice sides can detach in different order. Let's just be safe. */ @@ -48,11 +59,30 @@ struct ocfs2_live_connection { struct ocfs2_cluster_connection *oc_conn; }; +struct ocfs2_control_private { + struct list_head op_list; + int op_state; +}; + static atomic_t ocfs2_control_opened; static LIST_HEAD(ocfs2_live_connection_list); +static LIST_HEAD(ocfs2_control_private_list); static DEFINE_MUTEX(ocfs2_control_lock); +static inline void ocfs2_control_set_handshake_state(struct file *file, + int state) +{ + struct ocfs2_control_private *p = file->private_data; + p->op_state = state; +} + +static inline int ocfs2_control_get_handshake_state(struct file *file) +{ + struct ocfs2_control_private *p = file->private_data; + return p->op_state; +} + static struct ocfs2_live_connection *ocfs2_connection_find(const char *name) { size_t len = strlen(name); @@ -119,27 +149,115 @@ static void ocfs2_live_connection_drop(struct ocfs2_live_connection *c) kfree(c); } +static ssize_t ocfs2_control_cfu(char *target, size_t target_len, + const char __user *buf, size_t count) +{ + /* The T01 expects write(2) calls to have exactly one command */ + if (count != target_len) + return -EINVAL; + + if (copy_from_user(target, buf, target_len)) + return -EFAULT; + + return count; +} + +static ssize_t ocfs2_control_validate_handshake(struct file *file, + const char __user *buf, + size_t count) +{ + ssize_t ret; + char kbuf[OCFS2_CONTROL_PROTO_LEN]; + + ret = ocfs2_control_cfu(kbuf, OCFS2_CONTROL_PROTO_LEN, + buf, count); + if (ret != count) + return ret; + + if (strncmp(kbuf, OCFS2_CONTROL_PROTO, OCFS2_CONTROL_PROTO_LEN)) + return -EINVAL; + + atomic_inc(&ocfs2_control_opened); + ocfs2_control_set_handshake_state(file, + OCFS2_CONTROL_HANDSHAKE_VALID); + + + return count; +} + static ssize_t ocfs2_control_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { - return 0; + ssize_t ret; + + switch (ocfs2_control_get_handshake_state(file)) { + case OCFS2_CONTROL_HANDSHAKE_INVALID: + ret = -EINVAL; + break; + + case OCFS2_CONTROL_HANDSHAKE_READ: + ret = ocfs2_control_validate_handshake(file, buf, + count); + break; + + case OCFS2_CONTROL_HANDSHAKE_VALID: + ret = count; /* XXX */ + break; + + default: + BUG(); + ret = -EIO; + break; + } + + return ret; } +/* + * This is a naive version. If we ever have a new protocol, we'll expand + * it. Probably using seq_file. + */ static ssize_t ocfs2_control_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) { - return 0; + char *proto_string = OCFS2_CONTROL_PROTO; + size_t to_write = 0; + + if (*ppos >= OCFS2_CONTROL_PROTO_LEN) + return 0; + + to_write = OCFS2_CONTROL_PROTO_LEN - *ppos; + if (to_write > count) + to_write = count; + if (copy_to_user(buf, proto_string + *ppos, to_write)) + return -EFAULT; + + *ppos += to_write; + + /* Have we read the whole protocol list? */ + if (*ppos >= OCFS2_CONTROL_PROTO_LEN) + ocfs2_control_set_handshake_state(file, + OCFS2_CONTROL_HANDSHAKE_READ); + + return to_write; } static int ocfs2_control_release(struct inode *inode, struct file *file) { + struct ocfs2_control_private *p = file->private_data; + + mutex_lock(&ocfs2_control_lock); + + if (ocfs2_control_get_handshake_state(file) != + OCFS2_CONTROL_HANDSHAKE_VALID) + goto out; + if (atomic_dec_and_test(&ocfs2_control_opened)) { - mutex_lock(&ocfs2_control_lock); if (!list_empty(&ocfs2_live_connection_list)) { /* XXX: Do bad things! */ printk(KERN_ERR @@ -148,15 +266,31 @@ static int ocfs2_control_release(struct inode *inode, struct file *file) "an emergency restart!\n"); emergency_restart(); } - mutex_unlock(&ocfs2_control_lock); } +out: + list_del_init(&p->op_list); + file->private_data = NULL; + + mutex_unlock(&ocfs2_control_lock); + + kfree(p); + return 0; } static int ocfs2_control_open(struct inode *inode, struct file *file) { - atomic_inc(&ocfs2_control_opened); + struct ocfs2_control_private *p; + + p = kzalloc(sizeof(struct ocfs2_control_private), GFP_KERNEL); + if (!p) + return -ENOMEM; + + mutex_lock(&ocfs2_control_lock); + file->private_data = p; + list_add(&p->op_list, &ocfs2_control_private_list); + mutex_unlock(&ocfs2_control_lock); return 0; } |