sanchayanmaity/minix
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity
minix/servers/vfs/vnode.c
Thomas Veerman 958b25be50 - Introduce support for sticky bit. 
- Revise VFS-FS protocol and update VFS/MFS/ISOFS accordingly.
- Clean up MFS by removing old, dead code (backwards compatibility is broken by
  the new VFS-FS protocol, anyway) and rewrite other parts. Also, make sure all
  functions have proper banners and prototypes.
- VFS should always provide a (syntactically) valid path to the FS; no need for
  the FS to do sanity checks when leaving/entering mount points.
- Fix several bugs in MFS:
  - Several path lookup bugs in MFS.
  - A link can be too big for the path buffer.
  - A mountpoint can become inaccessible when the creation of a new inode
    fails, because the inode already exists and is a mountpoint.
- Introduce support for supplemental groups.
- Add test 46 to test supplemental group functionality (and removed obsolete
  suppl. tests from test 2).
- Clean up VFS (not everything is done yet).
- ISOFS now opens device read-only. This makes the -r flag in the mount command
  unnecessary (but will still report to be mounted read-write).
- Introduce PipeFS. PipeFS is a new FS that handles all anonymous and
  named pipes. However, named pipes still reside on the (M)FS, as they are part
  of the file system on disk. To make this work VFS now has a concept of
  'mapped' inodes, which causes read, write, truncate and stat requests to be
  redirected to the mapped FS, and all other requests to the original FS.
2009-12-20 20:27:14 +00:00

238 lines
6.5 KiB
C
Raw Blame History

/* This file contains the routines related to vnodes.
* The entry points are:
*
* get_vnode - increase counter and get details of an inode
* get_free_vnode - get a pointer to a free vnode obj
* find_vnode - find a vnode according to the FS endpoint and the inode num.
* dup_vnode - duplicate vnode (i.e. increase counter)
* put_vnode - drop vnode (i.e. decrease counter)
*/
#include "fs.h"
#include "vnode.h"
#include "vmnt.h"
#include "fproc.h"
#include "file.h"
#include <minix/vfsif.h>
/* Is vnode pointer reasonable? */
#define SANEVP(v) ((((v) >= &vnode[0] && (v) < &vnode[NR_VNODES])))
#define BADVP(v, f, l) printf("%s:%d: bad vp 0x%x\n", f, l, v)
/* vp check that returns 0 for use in check_vrefs() */
#define CHECKVN(v) if(!SANEVP(v)) { \
BADVP(v, __FILE__, __LINE__); \
return 0; \
}
/* vp check that panics */
#define ASSERTVP(v) if(!SANEVP(v)) { \
BADVP(v, __FILE__, __LINE__); panic("vfs", "bad vp", NO_NUM); }
/*===========================================================================*
* get_free_vnode *
*===========================================================================*/
PUBLIC struct vnode *get_free_vnode()
{
/* Find a free vnode slot in the vnode table (it's not actually allocated) */
struct vnode *vp;
for (vp = &vnode[0]; vp < &vnode[NR_VNODES]; ++vp) {
if (vp->v_ref_count == 0) {
vp->v_pipe = NO_PIPE;
vp->v_uid = -1;
vp->v_gid = -1;
vp->v_sdev = NO_DEV;
vp->v_mapfs_e = 0;
vp->v_mapinode_nr = 0;
return(vp);
}
}
err_code = ENFILE;
return(NIL_VNODE);
}
/*===========================================================================*
* find_vnode *
*===========================================================================*/
PUBLIC struct vnode *find_vnode(int fs_e, int numb)
{
/* Find a specified (FS endpoint and inode number) vnode in the
* vnode table */
struct vnode *vp;
for (vp = &vnode[0]; vp < &vnode[NR_VNODES]; ++vp)
if (vp->v_ref_count > 0 && vp->v_inode_nr == numb && vp->v_fs_e == fs_e)
return(vp);
return(NIL_VNODE);
}
/*===========================================================================*
* dup_vnode *
*===========================================================================*/
PUBLIC void dup_vnode(struct vnode *vp)
{
/* dup_vnode() is called to increment the vnode and therefore the
* referred inode's counter.
*/
ASSERTVP(vp);
vp->v_ref_count++;
}
/*===========================================================================*
* put_vnode *
*===========================================================================*/
PUBLIC void put_vnode(struct vnode *vp)
{
/* Decrease vnode's usage counter and decrease inode's usage counter in the
* corresponding FS process. Decreasing the fs_count each time we decrease the
* ref count would lead to poor performance. Instead, only decrease fs_count
* when the ref count hits zero. However, this could lead to fs_count to wrap.
* To prevent this, we drop the counter to 1 when the counter hits 256.
* We maintain fs_count as a sanity check to make sure VFS and the FS are in
* sync.
*/
ASSERTVP(vp);
if (vp->v_ref_count > 1) {
/* Decrease counter */
vp->v_ref_count--;
if (vp->v_fs_count > 256)
vnode_clean_refs(vp);
return;
}
/* A vnode that's not in use can't be put. */
if (vp->v_ref_count <= 0) {
printf("put_vnode: bad v_ref_count %d\n", vp->v_ref_count);
panic(__FILE__, "put_vnode failed", NO_NUM);
}
/* fs_count should indicate that the file is in use. */
if (vp->v_fs_count <= 0) {
printf("put_vnode: bad v_fs_count %d\n", vp->v_fs_count);
panic(__FILE__, "put_vnode failed", NO_NUM);
}
/* Tell FS we don't need this inode to be open anymore. */
req_putnode(vp->v_fs_e, vp->v_inode_nr, vp->v_fs_count);
/* This inode could've been mapped. If so, tell PFS to close it as well. */
if(vp->v_mapfs_e != 0 && vp->v_mapinode_nr != vp->v_inode_nr &&
vp->v_mapfs_e != vp->v_fs_e) {
req_putnode(vp->v_mapfs_e, vp->v_mapinode_nr, vp->v_mapfs_count);
}
vp->v_fs_count = 0;
vp->v_ref_count = 0;
vp->v_pipe = NO_PIPE;
vp->v_sdev = NO_DEV;
vp->v_mapfs_e = 0;
vp->v_mapinode_nr = 0;
vp->v_fs_count = 0;
}
/*===========================================================================*
* vnode_clean_refs *
*===========================================================================*/
PUBLIC void vnode_clean_refs(struct vnode *vp)
{
/* Tell the underlying FS to drop all reference but one. */
if (vp == NIL_VNODE) return;
if (vp->v_fs_count <= 1) return; /* Nothing to do */
/* Drop all references except one */
req_putnode(vp->v_fs_e, vp->v_inode_nr, vp->v_fs_count - 1);
vp->v_fs_count = 1;
}
#define REFVP(v) { vp = (v); CHECKVN(v); vp->v_ref_check++; }
#if DO_SANITYCHECKS
/*===========================================================================*
* check_vrefs *
*===========================================================================*/
PUBLIC int check_vrefs()
{
int i, bad;
int ispipe_flag, ispipe_mode;
struct vnode *vp;
struct vmnt *vmp;
struct fproc *rfp;
struct filp *f;
/* Clear v_ref_check */
for (vp = &vnode[0]; vp < &vnode[NR_VNODES]; ++vp)
vp->v_ref_check= 0;
/* Count reference for processes */
for (rfp=&fproc[0]; rfp < &fproc[NR_PROCS]; rfp++) {
if (rfp->fp_pid == PID_FREE)
continue;
if(rfp->fp_rd) REFVP(rfp->fp_rd);
if(rfp->fp_wd) REFVP(rfp->fp_wd);
}
/* Count references from filedescriptors */
for (f = &filp[0]; f < &filp[NR_FILPS]; f++)
{
if (f->filp_count == 0)
continue;
REFVP(f->filp_vno);
}
/* Count references to mount points */
for (vmp = &vmnt[0]; vmp < &vmnt[NR_MNTS]; ++vmp)
{
if (vmp->m_dev == NO_DEV)
continue;
REFVP(vmp->m_root_node);
if(vmp->m_mounted_on)
REFVP(vmp->m_mounted_on);
}
/* Check references */
bad= 0;
for (vp = &vnode[0]; vp < &vnode[NR_VNODES]; ++vp)
{
if (vp->v_ref_count != vp->v_ref_check)
{
printf(
"Bad reference count for inode %d on device 0x%x: found %d, listed %d\n",
vp->v_inode_nr, vp->v_dev, vp->v_ref_check,
vp->v_ref_count);
printf("last marked at %s, %d\n",
vp->v_file, vp->v_line);
bad= 1;
}
/* Also check v_pipe */
if (vp->v_ref_count != 0)
{
ispipe_flag= (vp->v_pipe == I_PIPE);
ispipe_mode= ((vp->v_mode & I_TYPE) == I_NAMED_PIPE);
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
Reference in a new issue View git blame Copy permalink