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#include "fs/vnode.h"
#include "errno.h"
#include "fs/stat.h"
#include "fs/vfs.h"
#include "kernel.h"
#include "mm/slab.h"
#include "util/debug.h"
#include "util/string.h"
#include <fs/vnode_specials.h>
#define MOBJ_TO_VNODE(o) CONTAINER_OF((o), vnode_t, vn_mobj)
static long vnode_get_pframe(mobj_t *o, uint64_t pagenum, long forwrite,
pframe_t **pfp);
static long vnode_fill_pframe(mobj_t *o, pframe_t *pf);
static long vnode_flush_pframe(mobj_t *o, pframe_t *pf);
static void vnode_destructor(mobj_t *o);
static mobj_ops_t vnode_mobj_ops = {.get_pframe = vnode_get_pframe,
.fill_pframe = vnode_fill_pframe,
.flush_pframe = vnode_flush_pframe,
.destructor = vnode_destructor};
/**
* locks the vnodes in the order of their inode number,
* in the case that they are the same vnode, then only one vnode is locked.
*
* this scheme prevents the A->B/B->A locking problem, but it only
* works only if the `vlock_in_order` function is used in all cases where 2
* nodes must be locked.
*/
void vlock_in_order(vnode_t *a, vnode_t *b)
{
/* these vnode's must be on the same filesystem */
KASSERT(a->vn_fs == b->vn_fs);
if (a->vn_vno == b->vn_vno)
{
vlock(a);
return;
}
/* */
if (S_ISDIR(a->vn_mode) && S_ISDIR(b->vn_mode))
{
if (namev_is_descendant(a, b))
{
vlock(b);
vlock(a);
return;
}
else if (namev_is_descendant(b, a))
{
vlock(a);
vlock(b);
return;
}
}
else if (S_ISDIR(a->vn_mode))
{
vlock(a);
vlock(b);
}
else if (S_ISDIR(b->vn_mode))
{
vlock(b);
vlock(a);
}
else if (a->vn_vno < b->vn_vno)
{
vlock(a);
vlock(b);
}
else
{
vlock(b);
vlock(a);
}
}
void vunlock_in_order(vnode_t *a, vnode_t *b)
{
if (a->vn_vno == b->vn_vno)
{
vunlock(a);
return;
}
vunlock(a);
vunlock(b);
}
void await_vnode_loaded(vnode_t *vnode)
{
/* blocks until the vnode's vn_state is loaded */
while (vnode->vn_state != VNODE_LOADED)
{
sched_sleep_on(&vnode->vn_waitq);
}
KASSERT(vnode->vn_state == VNODE_LOADED);
}
void notify_vnode_loaded(vnode_t *vn)
{
/* set the state to loaded and release all waiters */
vn->vn_state = VNODE_LOADED;
sched_broadcast_on(&vn->vn_waitq);
}
void vnode_init(vnode_t *vn, fs_t *fs, ino_t ino, int state)
{
vn->vn_state = VNODE_LOADING;
vn->vn_fs = fs;
vn->vn_vno = ino;
sched_queue_init(&vn->vn_waitq);
mobj_init(&vn->vn_mobj, MOBJ_VNODE, &vnode_mobj_ops);
KASSERT(vn->vn_mobj.mo_refcount);
}
vnode_t *__vget(fs_t *fs, ino_t ino, int get_locked)
{
find:
kmutex_lock(&fs->vnode_list_mutex);
list_iterate(&fs->vnode_list, vn, vnode_t, vn_link)
{
if (vn->vn_vno == ino)
{
if (atomic_inc_not_zero(&vn->vn_mobj.mo_refcount))
{
/* reference acquired, we can release the per-FS list */
kmutex_unlock(&fs->vnode_list_mutex);
await_vnode_loaded(vn);
if (get_locked)
{
vlock(vn);
}
return vn;
}
else
{
/* count must be 0, wait and try again later */
kmutex_unlock(&fs->vnode_list_mutex);
sched_yield();
goto find;
}
}
}
/* vnode does not exist, must allocate one */
dbg(DBG_VFS, "creating vnode %d\n", ino);
vnode_t *vn = slab_obj_alloc(fs->fs_vnode_allocator);
KASSERT(vn);
memset(vn, 0, sizeof(vnode_t));
/* initialize the vnode state */
vnode_init(vn, fs, ino, VNODE_LOADING);
/* add the vnode to the per-FS list, lock the vnode, and release the list
* (unblocking other `vget` calls) */
list_insert_tail(&fs->vnode_list, &vn->vn_link);
vlock(vn);
kmutex_unlock(&fs->vnode_list_mutex);
/* load the vnode */
vn->vn_fs->fs_ops->read_vnode(vn->vn_fs, vn);
if (S_ISCHR(vn->vn_mode) || S_ISBLK(vn->vn_mode))
{
init_special_vnode(vn);
}
/* notify potential waiters that the vnode is ready for use and return */
notify_vnode_loaded(vn);
if (!get_locked)
{
vunlock(vn);
}
return vn;
}
inline vnode_t *vget(fs_t *fs, ino_t ino) { return __vget(fs, ino, 0); }
inline vnode_t *vget_locked(fs_t *fs, ino_t ino) { return __vget(fs, ino, 1); }
inline void vref(vnode_t *vn) { mobj_ref(&vn->vn_mobj); }
inline void vlock(vnode_t *vn) { mobj_lock(&vn->vn_mobj); }
inline void vunlock(vnode_t *vn) { mobj_unlock(&vn->vn_mobj); }
inline void vput(struct vnode **vnp)
{
vnode_t *vn = *vnp;
*vnp = NULL;
mobj_t *mobj = &vn->vn_mobj;
mobj_put(&mobj);
}
inline void vput_locked(struct vnode **vnp)
{
vunlock(*vnp);
vput(vnp);
}
static long vnode_get_pframe(mobj_t *o, uint64_t pagenum, long forwrite,
pframe_t **pfp)
{
vnode_t *vnode = MOBJ_TO_VNODE(o);
KASSERT(vnode->vn_ops->get_pframe);
return vnode->vn_ops->get_pframe(vnode, pagenum, forwrite, pfp);
}
static long vnode_fill_pframe(mobj_t *o, pframe_t *pf)
{
vnode_t *vnode = MOBJ_TO_VNODE(o);
KASSERT(vnode->vn_ops->fill_pframe);
return vnode->vn_ops->fill_pframe(vnode, pf);
}
static long vnode_flush_pframe(mobj_t *o, pframe_t *pf)
{
vnode_t *vnode = MOBJ_TO_VNODE(o);
KASSERT(vnode->vn_ops->flush_pframe);
return vnode->vn_ops->flush_pframe(vnode, pf);
}
static void vnode_destructor(mobj_t *o)
{
vnode_t *vn = MOBJ_TO_VNODE(o);
dbg(DBG_VFS, "destroying vnode %d\n", vn->vn_vno);
/* lock, flush, and delete the vnode */
KASSERT(!o->mo_refcount);
vlock(vn);
KASSERT(!o->mo_refcount);
KASSERT(!kmutex_has_waiters(&o->mo_mutex));
mobj_flush(o);
if (vn->vn_fs->fs_ops->delete_vnode)
{
vn->vn_fs->fs_ops->delete_vnode(vn->vn_fs, vn);
}
KASSERT(!kmutex_has_waiters(&o->mo_mutex));
vunlock(vn);
/* remove the vnode from the list and free it*/
kmutex_lock(&vn->vn_fs->vnode_list_mutex);
KASSERT(list_link_is_linked(&vn->vn_link));
list_remove(&vn->vn_link);
kmutex_unlock(&vn->vn_fs->vnode_list_mutex);
slab_obj_free(vn->vn_fs->fs_vnode_allocator, vn);
}
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