*
*/
+// Welcome to The Mountain O'Shit! :)
+
+/*
+ TODO vfs & device todos checklist
+
+ It is overseen by Twilight Sparkle ;)
+
+ 1. Get inodes hooked into lru
+ 2. Get dnodes hooked into lru
+ 3. Get inodes properly hashed so they can be reused by underling fs (CHECKED)
+ 4. (lru) Add a callback function (or destructor) for eviction.
+ [good idea] or a constructor/destructor pattern in cake allocator ?
+ 5. (mount) Figure out a way to identify a busy mount point before unmount
+ maybe a unified mount_point structure that maintain a referencing
+ counter on any dnodes within the subtree? Such a counter will only
+ increament if a file is opened or a dnode is being used as working
+ directory and decreamenting conversely.
+ 6. (mount) Ability to track all mount points (including sub-mounts)
+ so we can be confident to clean up everything when we unmount.
+ 7. (mount) Figure out a way to acquire the device represented by a dnode.
+ so it can be used to mount. (e.g. we wish to get `struct device*`
+ out of the dnode at /dev/sda)
+ [tip] we should pay attention at twifs and add a private_data field
+ under struct v_dnode?
+ 8. (mount) Then, we should refactor on mount/unmount mechanism.
+ 9. (mount) (future) Ability to mount any thing? e.g. Linux can mount a disk
+ image file using a so called "loopback" pseudo device. Maybe
+ we can do similar thing in Lunaix? A block device emulation
+ above the regular file when we mount it on.
+ 10. (device) device number (dev_t) allocation
+ [good idea] <class>:<subclass>:<uniq_id> composition
+*/
+
#include <klibc/string.h>
#include <lunaix/dirent.h>
#include <lunaix/foptions.h>
#include <lunaix/fs/twifs.h>
#define PATH_DELIM '/'
-#define DNODE_HASHTABLE_BITS 10
-#define DNODE_HASHTABLE_SIZE (1 << DNODE_HASHTABLE_BITS)
-#define DNODE_HASH_MASK (DNODE_HASHTABLE_SIZE - 1)
-#define DNODE_HASHBITS (32 - DNODE_HASHTABLE_BITS)
+#define HASHTABLE_BITS 10
+#define HASHTABLE_SIZE (1 << HASHTABLE_BITS)
+#define HASH_MASK (HASHTABLE_SIZE - 1)
+#define HASHBITS (32 - HASHTABLE_BITS)
#define lock_inode(inode) mutex_lock(&inode->lock)
#define unlock_inode(inode) mutex_unlock(&inode->lock)
static struct cake_pile* fd_pile;
static struct v_superblock* root_sb;
-static struct hbucket* dnode_cache;
-
-static int fs_id = 0;
+static struct hbucket *dnode_cache, *inode_cache;
struct hstr vfs_ddot = HSTR("..", 2);
struct hstr vfs_dot = HSTR(".", 1);
struct hstr vfs_empty = HSTR("", 0);
-struct v_dnode*
-vfs_d_alloc();
-
-void
-vfs_d_free(struct v_dnode* dnode);
-
struct v_superblock*
vfs_sb_alloc();
superblock_pile =
cake_new_pile("sb_cache", sizeof(struct v_superblock), 1, 0);
- dnode_cache = vzalloc(DNODE_HASHTABLE_SIZE * sizeof(struct hbucket));
+ dnode_cache = vzalloc(HASHTABLE_SIZE * sizeof(struct hbucket));
+ inode_cache = vzalloc(HASHTABLE_SIZE * sizeof(struct hbucket));
hstr_rehash(&vfs_ddot, HSTR_FULL_HASH);
hstr_rehash(&vfs_dot, HSTR_FULL_HASH);
// 创建一个根superblock，用来蕴含我们的根目录。
root_sb = vfs_sb_alloc();
root_sb->root = vfs_d_alloc();
- root_sb->root->inode = vfs_i_alloc();
+ root_sb->root->inode = vfs_i_alloc(root_sb, 0);
}
inline struct hbucket*
// 与parent的指针值做加法，来减小碰撞的可能性。
_hash += (uint32_t)parent;
// 确保低位更加随机
- _hash = _hash ^ (_hash >> DNODE_HASHBITS);
+ _hash = _hash ^ (_hash >> HASHBITS);
*hash = _hash;
- return &dnode_cache[_hash & DNODE_HASH_MASK];
+ return &dnode_cache[_hash & HASH_MASK];
}
struct v_dnode*
void
vfs_dcache_add(struct v_dnode* parent, struct v_dnode* dnode)
{
+ atomic_fetch_add(&dnode->ref_count, 1);
+ dnode->parent = parent;
+ llist_append(&parent->children, &dnode->siblings);
struct hbucket* bucket = __dcache_hash(parent, &dnode->name.hash);
hlist_add(&bucket->head, &dnode->hash_list);
}
void
-vfs_dcache_rehash(struct v_dnode* parent, struct v_dnode* dnode)
+vfs_dcache_remove(struct v_dnode* dnode)
{
+ assert(dnode->ref_count == 1);
+
+ llist_delete(&dnode->siblings);
hlist_delete(&dnode->hash_list);
+
+ dnode->parent = NULL;
+ atomic_fetch_sub(&dnode->ref_count, 1);
+}
+
+void
+vfs_dcache_rehash(struct v_dnode* new_parent, struct v_dnode* dnode)
+{
hstr_rehash(&dnode->name, HSTR_FULL_HASH);
- vfs_dcache_add(parent, dnode);
+ vfs_dcache_remove(dnode);
+ vfs_dcache_add(new_parent, dnode);
}
int
}
vfs_dcache_add(current_level, dnode);
-
- dnode->parent = current_level;
- llist_append(¤t_level->children, &dnode->siblings);
}
unlock_dnode(current_level);
struct v_superblock* sb = vfs_sb_alloc();
sb->dev = device;
- sb->fs_id = fs_id++;
+ sb->fs_id = fs->fs_id;
int errno = 0;
if (!(errno = fs->mount(sb, mnt_point))) {
int
vfs_unmount_at(struct v_dnode* mnt_point)
{
- // FIXME mnt point check & deal with the detached dcache subtree
+ // FIXME deal with the detached dcache subtree
int errno = 0;
struct v_superblock* sb = mnt_point->super_block;
if (!sb) {
return EINVAL;
}
+
+ if (sb->root != mnt_point) {
+ return EINVAL;
+ }
+
if (!(errno = sb->fs->unmount(sb))) {
struct v_dnode* fs_root = sb->root;
- llist_delete(&fs_root->siblings);
+ vfs_dcache_remove(fs_root);
+
llist_delete(&sb->sb_list);
- hlist_delete(&fs_root->hash_list);
vfs_sb_free(sb);
vfs_d_free(fs_root);
}
errno = ENOTSUP;
} else if (!(errno = to_link->inode->ops.link(to_link->inode, name))) {
name->inode = to_link->inode;
- atomic_fetch_add(&to_link->inode->link_count, 1);
+ to_link->inode->link_count++;
}
unlock_inode(to_link->inode);
void
vfs_d_free(struct v_dnode* dnode)
{
+ if (dnode->ref_count) {
+ // it can be only freed if no one is refering
+ return;
+ }
if (dnode->inode && dnode->inode->link_count) {
dnode->inode->link_count--;
}
+
+ // Make sure the children de-referencing their parent.
+ // With lru presented, the eviction will be propagated over the entire
+ // detached subtree eventually
+ struct v_dnode *pos, *n;
+ llist_for_each(pos, n, &dnode->children, siblings)
+ {
+ vfs_dcache_remove(pos);
+ }
+
vfree(dnode->name.value);
cake_release(dnode_pile, dnode);
}
struct v_inode*
-vfs_i_alloc()
+vfs_i_alloc(dev_t device_id, uint32_t inode_id)
{
- struct v_inode* inode = cake_grab(inode_pile);
- memset(inode, 0, sizeof(*inode));
- inode->link_count = 1;
- mutex_init(&inode->lock);
+ // 我们这里假设每个文件系统与设备是一一对应（毕竟一个分区不可能有两个不同的文件系统）
+ // 而每个文件系统所产生的 v_inode 缓存必须要和其他文件系统产生的区分开来。
+ // 这也就是说，每个 v_inode 的 id
+ // 必须要由设备ID，和该虚拟inode缓存所对应的物理inode
+ // 相对于其所在的文件系统的id，进行组成！
+ inode_id = hash_32(inode_id ^ device_id, HASH_SIZE_BITS);
+ inode_id = (inode_id >> HASHBITS) ^ inode_id;
+
+ struct hbucket* slot = &inode_cache[inode_id & HASH_MASK];
+ struct v_inode *pos, *n;
+ hashtable_bucket_foreach(slot, pos, n, hash_list)
+ {
+ if (pos->id == inode_id) {
+ return pos;
+ }
+ }
+
+ pos = cake_grab(inode_pile);
+ memset(pos, 0, sizeof(*pos));
+
+ pos->id = inode_id;
+ pos->link_count = 1;
+
+ mutex_init(&pos->lock);
+
+ hlist_add(&slot->head, &pos->hash_list);
- return inode;
+ return pos;
}
void
vfs_i_free(struct v_inode* inode)
{
+ hlist_delete(&inode->hash_list);
cake_release(inode_pile, inode);
}
if ((dnode->inode->itype & VFS_IFDIR)) {
errno = dnode->inode->ops.rmdir(dnode->inode);
if (!errno) {
- llist_delete(&dnode->siblings);
- hlist_delete(&dnode->hash_list);
+ vfs_dcache_remove(dnode);
unlock_inode(dnode->inode);
vfs_d_free(dnode);
{
struct v_inode* inode = dnode->inode;
- if (dnode->ref_count) {
+ if (dnode->ref_count > 1) {
return EBUSY;
}
errno = inode->ops.unlink(inode);
if (!errno) {
inode->link_count--;
- llist_delete(&dnode->siblings);
- hlist_delete(&dnode->hash_list);
+ vfs_dcache_remove(dnode);
vfs_d_free(dnode);
}
} else {
}
if (__current->cwd) {
- __current->cwd->ref_count--;
+ atomic_fetch_add(&__current->cwd->ref_count, 1);
}
- dnode->ref_count--;
+ atomic_fetch_sub(&dnode->ref_count, 1);
__current->cwd = dnode;
unlock_dnode(dnode);
return 0;
}
- if (current->ref_count || target->ref_count) {
+ if (current->ref_count > 1 || target->ref_count > 1) {
return EBUSY;
}
}
// re-position current
- current->parent = newparent;
hstrcpy(¤t->name, &target->name);
- llist_delete(¤t->siblings);
- llist_append(&newparent->children, ¤t->siblings);
vfs_dcache_rehash(newparent, current);
// detach target
- llist_delete(&target->siblings);
- hlist_delete(&target->hash_list);
+ vfs_dcache_remove(target);
unlock_dnode(target);
goto done;
}
+ if (mnt->ref_count > 1) {
+ errno = EBUSY;
+ goto done;
+ }
+
// FIXME should not touch the underlying fs!
struct device* device =
(struct device*)((struct twifs_node*)dev->inode->data)->data;
git://scm.lunaixsky.com / lunaix-os.git / commitdiff