238 lines
6.5 KiB
C
238 lines
6.5 KiB
C
/* 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 "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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/* Is vnode pointer reasonable? */
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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 0x%x\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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/*===========================================================================*
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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) {
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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 = 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 numb)
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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 == numb && 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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* 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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ASSERTVP(vp);
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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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return;
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}
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/* A vnode that's not in use can't be put. */
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if (vp->v_ref_count <= 0) {
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printf("put_vnode: bad v_ref_count %d\n", vp->v_ref_count);
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panic("put_vnode failed");
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}
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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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printf("put_vnode: bad v_fs_count %d\n", vp->v_fs_count);
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panic("put_vnode failed");
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}
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/* Tell FS we don't need this inode to be open anymore. */
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req_putnode(vp->v_fs_e, vp->v_inode_nr, vp->v_fs_count);
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/* This inode could've been mapped. If so, tell PFS to close it as well. */
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if(vp->v_mapfs_e != 0 && vp->v_mapinode_nr != vp->v_inode_nr &&
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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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}
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vp->v_fs_count = 0;
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vp->v_ref_count = 0;
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vp->v_pipe = NO_PIPE;
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vp->v_sdev = NO_DEV;
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vp->v_mapfs_e = 0;
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vp->v_mapinode_nr = 0;
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vp->v_mapfs_count = 0;
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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)
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{
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printf(
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"Bad v_pipe for inode %d on device 0x%x: found %d, mode 0%o\n",
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vp->v_inode_nr, vp->v_dev, vp->v_pipe,
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vp->v_mode);
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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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}
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}
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return !bad;
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}
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#endif
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