388 lines
10 KiB
C
388 lines
10 KiB
C
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/* This file contains the routines related to vnodes.
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* The entry points are:
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*
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* get_vnode - increase counter and get details of an inode
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* get_free_vnode - get a pointer to a free vnode obj
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* find_vnode - find a vnode according to the FS endpoint and the inode num.
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* dup_vnode - duplicate vnode (i.e. increase counter)
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* put_vnode - drop vnode (i.e. decrease counter)
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*/
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#include "fs.h"
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#include "threads.h"
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#include "vnode.h"
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#include "vmnt.h"
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#include "fproc.h"
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#include "file.h"
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#include <minix/vfsif.h>
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#include <assert.h>
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/* Is vnode pointer reasonable? */
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#if NDEBUG
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#define SANEVP(v)
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#define CHECKVN(v)
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#define ASSERTVP(v)
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#else
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#define SANEVP(v) ((((v) >= &vnode[0] && (v) < &vnode[NR_VNODES])))
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#define BADVP(v, f, l) printf("%s:%d: bad vp %p\n", f, l, v)
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/* vp check that returns 0 for use in check_vrefs() */
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#define CHECKVN(v) if(!SANEVP(v)) { \
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BADVP(v, __FILE__, __LINE__); \
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return 0; \
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}
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/* vp check that panics */
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#define ASSERTVP(v) if(!SANEVP(v)) { \
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BADVP(v, __FILE__, __LINE__); panic("bad vp"); }
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#endif
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#if LOCK_DEBUG
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/*===========================================================================*
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* check_vnode_locks_by_me *
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*===========================================================================*/
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PUBLIC void check_vnode_locks_by_me(struct fproc *rfp)
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{
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/* Check whether this thread still has locks held on vnodes */
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struct vnode *vp;
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for (vp = &vnode[0]; vp < &vnode[NR_VNODES]; vp++) {
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if (tll_locked_by_me(&vp->v_lock)) {
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panic("Thread %d still holds vnode lock on vp %x call_nr=%d\n",
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mthread_self(), vp, call_nr);
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}
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}
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if (rfp->fp_vp_rdlocks != 0)
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panic("Thread %d still holds read locks on a vnode (%d) call_nr=%d\n",
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mthread_self(), rfp->fp_vp_rdlocks, call_nr);
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}
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#endif
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/*===========================================================================*
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* check_vnode_locks *
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*===========================================================================*/
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PUBLIC void check_vnode_locks()
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{
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struct vnode *vp;
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int count = 0;
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for (vp = &vnode[0]; vp < &vnode[NR_VNODES]; vp++)
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if (is_vnode_locked(vp)) {
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count++;
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}
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if (count) panic("%d locked vnodes\n", count);
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#if 0
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printf("check_vnode_locks OK\n");
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#endif
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}
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/*===========================================================================*
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* get_free_vnode *
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*===========================================================================*/
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PUBLIC struct vnode *get_free_vnode()
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{
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/* Find a free vnode slot in the vnode table (it's not actually allocated) */
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struct vnode *vp;
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for (vp = &vnode[0]; vp < &vnode[NR_VNODES]; ++vp) {
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if (vp->v_ref_count == 0 && !is_vnode_locked(vp)) {
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vp->v_pipe = NO_PIPE;
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vp->v_uid = -1;
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vp->v_gid = -1;
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vp->v_sdev = NO_DEV;
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vp->v_mapfs_e = NONE;
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vp->v_mapfs_count = 0;
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vp->v_mapinode_nr = 0;
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return(vp);
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}
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}
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err_code = ENFILE;
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return(NULL);
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}
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/*===========================================================================*
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* find_vnode *
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*===========================================================================*/
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PUBLIC struct vnode *find_vnode(int fs_e, int ino)
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{
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/* Find a specified (FS endpoint and inode number) vnode in the
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* vnode table */
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struct vnode *vp;
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for (vp = &vnode[0]; vp < &vnode[NR_VNODES]; ++vp)
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if (vp->v_ref_count > 0 && vp->v_inode_nr == ino && vp->v_fs_e == fs_e)
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return(vp);
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return(NULL);
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}
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/*===========================================================================*
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* is_vnode_locked *
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*===========================================================================*/
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PUBLIC int is_vnode_locked(struct vnode *vp)
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{
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/* Find out whether a thread holds a lock on this vnode or is trying to obtain
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* a lock. */
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ASSERTVP(vp);
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return(tll_islocked(&vp->v_lock) || tll_haspendinglock(&vp->v_lock));
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}
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/*===========================================================================*
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* init_vnodes *
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*===========================================================================*/
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PUBLIC void init_vnodes(void)
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{
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struct vnode *vp;
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for (vp = &vnode[0]; vp < &vnode[NR_VNODES]; ++vp) {
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vp->v_fs_e = NONE;
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vp->v_mapfs_e = NONE;
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vp->v_inode_nr = 0;
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vp->v_ref_count = 0;
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vp->v_fs_count = 0;
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vp->v_mapfs_count = 0;
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tll_init(&vp->v_lock);
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}
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}
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/*===========================================================================*
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* lock_vnode *
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*===========================================================================*/
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PUBLIC int lock_vnode(struct vnode *vp, tll_access_t locktype)
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{
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int r;
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ASSERTVP(vp);
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r = tll_lock(&vp->v_lock, locktype);
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#if LOCK_DEBUG
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if (locktype == VNODE_READ) {
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fp->fp_vp_rdlocks++;
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}
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#endif
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if (r == EBUSY) return(r);
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return(OK);
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}
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/*===========================================================================*
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* unlock_vnode *
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*===========================================================================*/
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PUBLIC void unlock_vnode(struct vnode *vp)
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{
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int i;
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register struct vnode *rvp;
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struct worker_thread *w;
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ASSERTVP(vp);
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#if LOCK_DEBUG
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/* Decrease read-only lock counter when not locked as VNODE_OPCL or
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* VNODE_WRITE */
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if (!tll_locked_by_me(&vp->v_lock)) {
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fp->fp_vp_rdlocks--;
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}
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for (i = 0; i < NR_VNODES; i++) {
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rvp = &vnode[i];
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w = rvp->v_lock.t_write;
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assert(w != self);
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while (w && w->w_next != NULL) {
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w = w->w_next;
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assert(w != self);
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}
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w = rvp->v_lock.t_serial;
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assert(w != self);
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while (w && w->w_next != NULL) {
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w = w->w_next;
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assert(w != self);
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}
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}
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#endif
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tll_unlock(&vp->v_lock);
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}
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/*===========================================================================*
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* dup_vnode *
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*===========================================================================*/
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PUBLIC void dup_vnode(struct vnode *vp)
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{
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/* dup_vnode() is called to increment the vnode and therefore the
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* referred inode's counter.
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*/
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ASSERTVP(vp);
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vp->v_ref_count++;
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}
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/*===========================================================================*
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* put_vnode *
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*===========================================================================*/
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PUBLIC void put_vnode(struct vnode *vp)
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{
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/* Decrease vnode's usage counter and decrease inode's usage counter in the
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* corresponding FS process. Decreasing the fs_count each time we decrease the
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* ref count would lead to poor performance. Instead, only decrease fs_count
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* when the ref count hits zero. However, this could lead to fs_count to wrap.
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* To prevent this, we drop the counter to 1 when the counter hits 256.
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* We maintain fs_count as a sanity check to make sure VFS and the FS are in
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* sync.
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*/
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int r, lock_vp;
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ASSERTVP(vp);
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/* Lock vnode. It's quite possible this thread already has a lock on this
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* vnode. That's no problem, because the reference counter will not decrease
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* to zero in that case. However, if the counter does decrease to zero *and*
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* is already locked, we have a consistency problem somewhere. */
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lock_vp = lock_vnode(vp, VNODE_OPCL);
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if (vp->v_ref_count > 1) {
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/* Decrease counter */
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vp->v_ref_count--;
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if (vp->v_fs_count > 256)
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vnode_clean_refs(vp);
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if (lock_vp != EBUSY) unlock_vnode(vp);
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return;
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}
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/* If we already had a lock, there is a consistency problem */
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assert(lock_vp != EBUSY);
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tll_upgrade(&vp->v_lock); /* Make sure nobody else accesses this vnode */
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/* A vnode that's not in use can't be put back. */
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if (vp->v_ref_count <= 0)
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panic("put_vnode failed: bad v_ref_count %d\n", vp->v_ref_count);
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/* fs_count should indicate that the file is in use. */
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if (vp->v_fs_count <= 0)
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panic("put_vnode failed: bad v_fs_count %d\n", vp->v_fs_count);
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/* Tell FS we don't need this inode to be open anymore. */
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r = req_putnode(vp->v_fs_e, vp->v_inode_nr, vp->v_fs_count);
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if (r != OK) {
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printf("VFS: putnode failed: %d\n", r);
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util_stacktrace();
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}
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/* This inode could've been mapped. If so, tell mapped FS to close it as
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* well. If mapped onto same FS, this putnode is not needed. */
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if (vp->v_mapfs_e != NONE && vp->v_mapfs_e != vp->v_fs_e)
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req_putnode(vp->v_mapfs_e, vp->v_mapinode_nr, vp->v_mapfs_count);
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vp->v_fs_count = 0;
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vp->v_ref_count = 0;
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vp->v_mapfs_count = 0;
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unlock_vnode(vp);
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}
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/*===========================================================================*
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* vnode_clean_refs *
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*===========================================================================*/
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PUBLIC void vnode_clean_refs(struct vnode *vp)
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{
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/* Tell the underlying FS to drop all reference but one. */
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if (vp == NULL) return;
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if (vp->v_fs_count <= 1) return; /* Nothing to do */
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/* Drop all references except one */
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req_putnode(vp->v_fs_e, vp->v_inode_nr, vp->v_fs_count - 1);
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vp->v_fs_count = 1;
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}
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#define REFVP(v) { vp = (v); CHECKVN(v); vp->v_ref_check++; }
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#if DO_SANITYCHECKS
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/*===========================================================================*
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* check_vrefs *
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*===========================================================================*/
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PUBLIC int check_vrefs()
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{
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int i, bad;
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int ispipe_flag, ispipe_mode;
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struct vnode *vp;
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struct vmnt *vmp;
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struct fproc *rfp;
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struct filp *f;
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/* Clear v_ref_check */
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for (vp = &vnode[0]; vp < &vnode[NR_VNODES]; ++vp)
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vp->v_ref_check= 0;
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/* Count reference for processes */
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for (rfp=&fproc[0]; rfp < &fproc[NR_PROCS]; rfp++) {
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if (rfp->fp_pid == PID_FREE)
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continue;
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if(rfp->fp_rd) REFVP(rfp->fp_rd);
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if(rfp->fp_wd) REFVP(rfp->fp_wd);
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}
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/* Count references from filedescriptors */
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for (f = &filp[0]; f < &filp[NR_FILPS]; f++)
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{
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if (f->filp_count == 0)
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continue;
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REFVP(f->filp_vno);
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}
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/* Count references to mount points */
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for (vmp = &vmnt[0]; vmp < &vmnt[NR_MNTS]; ++vmp)
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{
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if (vmp->m_dev == NO_DEV)
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continue;
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REFVP(vmp->m_root_node);
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if(vmp->m_mounted_on)
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REFVP(vmp->m_mounted_on);
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}
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/* Check references */
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bad= 0;
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for (vp = &vnode[0]; vp < &vnode[NR_VNODES]; ++vp)
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{
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if (vp->v_ref_count != vp->v_ref_check)
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{
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printf(
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"Bad reference count for inode %d on device 0x%x: found %d, listed %d\n",
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vp->v_inode_nr, vp->v_dev, vp->v_ref_check,
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vp->v_ref_count);
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printf("last marked at %s, %d\n",
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vp->v_file, vp->v_line);
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bad= 1;
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}
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/* Also check v_pipe */
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if (vp->v_ref_count != 0)
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{
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ispipe_flag= (vp->v_pipe == I_PIPE);
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ispipe_mode= ((vp->v_mode & I_TYPE) == I_NAMED_PIPE);
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if (ispipe_flag != ispipe_mode)
|
||
|
|
{
|
||
|
|
printf(
|
||
|
|
"Bad v_pipe for inode %d on device 0x%x: found %d, mode 0%o\n",
|
||
|
|
vp->v_inode_nr, vp->v_dev, vp->v_pipe,
|
||
|
|
vp->v_mode);
|
||
|
|
printf("last marked at %s, %d\n",
|
||
|
|
vp->v_file, vp->v_line);
|
||
|
|
bad= 1;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
return !bad;
|
||
|
|
}
|
||
|
|
#endif
|