minix/servers/vfs/vmnt.c

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/* Virtual mount table related routines.
*
*/
#include "fs.h"
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#include "threads.h"
#include "vmnt.h"
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#include <assert.h>
#include "fproc.h"
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static int is_vmnt_locked(struct vmnt *vmp);
static void clear_vmnt(struct vmnt *vmp);
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/* Is vmp pointer reasonable? */
#define SANEVMP(v) ((((v) >= &vmnt[0] && (v) < &vmnt[NR_MNTS])))
#define BADVMP(v, f, l) printf("%s:%d: bad vmp %p\n", f, l, v)
/* vp check that panics */
#define ASSERTVMP(v) if(!SANEVMP(v)) { \
BADVMP(v, __FILE__, __LINE__); panic("bad vmp"); }
#if LOCK_DEBUG
/*===========================================================================*
* check_vmnt_locks_by_me *
*===========================================================================*/
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void check_vmnt_locks_by_me(struct fproc *rfp)
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{
/* Check whether this thread still has locks held on vmnts */
struct vmnt *vmp;
for (vmp = &vmnt[0]; vmp < &vmnt[NR_MNTS]; vmp++) {
if (tll_locked_by_me(&vmp->m_lock))
panic("Thread %d still holds vmnt lock on vmp %p call_nr=%d\n",
mthread_self(), vmp, call_nr);
}
if (rfp->fp_vmnt_rdlocks != 0)
panic("Thread %d still holds read locks on a vmnt (%d) call_nr=%d\n",
mthread_self(), rfp->fp_vmnt_rdlocks, call_nr);
}
#endif
/*===========================================================================*
* check_vmnt_locks *
*===========================================================================*/
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void check_vmnt_locks()
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{
struct vmnt *vmp;
int count = 0;
for (vmp = &vmnt[0]; vmp < &vmnt[NR_MNTS]; vmp++)
if (is_vmnt_locked(vmp)) {
count++;
printf("vmnt %p is %s, fs_e=%d dev=%d\n", vmp, (tll_islocked(&vmp->m_lock) ? "locked":"pending locked"), vmp->m_fs_e, vmp->m_dev);
}
if (count) panic("%d locked vmnts\n", count);
#if 0
printf("check_vmnt_locks OK\n");
#endif
}
/*===========================================================================*
* mark_vmnt_free *
*===========================================================================*/
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void mark_vmnt_free(struct vmnt *vmp)
{
ASSERTVMP(vmp);
vmp->m_fs_e = NONE;
vmp->m_dev = NO_DEV;
}
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/*===========================================================================*
* clear_vmnt *
*===========================================================================*/
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static void clear_vmnt(struct vmnt *vmp)
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{
/* Reset vmp to initial parameters */
ASSERTVMP(vmp);
vmp->m_fs_e = NONE;
vmp->m_dev = NO_DEV;
vmp->m_flags = 0;
vmp->m_mounted_on = NULL;
vmp->m_root_node = NULL;
vmp->m_label[0] = '\0';
vmp->m_comm.c_max_reqs = 1;
vmp->m_comm.c_cur_reqs = 0;
vmp->m_comm.c_req_queue = NULL;
}
/*===========================================================================*
* get_free_vmnt *
*===========================================================================*/
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struct vmnt *get_free_vmnt(void)
{
struct vmnt *vmp;
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for (vmp = &vmnt[0]; vmp < &vmnt[NR_MNTS]; ++vmp) {
if (vmp->m_dev == NO_DEV) {
clear_vmnt(vmp);
return(vmp);
}
}
return(NULL);
}
/*===========================================================================*
* find_vmnt *
*===========================================================================*/
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struct vmnt *find_vmnt(endpoint_t fs_e)
{
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/* Find the vmnt belonging to an FS with endpoint 'fs_e' iff it's in use */
struct vmnt *vp;
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for (vp = &vmnt[0]; vp < &vmnt[NR_MNTS]; ++vp)
if (vp->m_fs_e == fs_e && vp->m_dev != NO_DEV)
return(vp);
return(NULL);
}
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/*===========================================================================*
* init_vmnts *
*===========================================================================*/
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void init_vmnts(void)
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{
/* Initialize vmnt table */
struct vmnt *vmp;
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for (vmp = &vmnt[0]; vmp < &vmnt[NR_MNTS]; vmp++) {
clear_vmnt(vmp);
tll_init(&vmp->m_lock);
}
}
/*===========================================================================*
* is_vmnt_locked *
*===========================================================================*/
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static int is_vmnt_locked(struct vmnt *vmp)
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{
ASSERTVMP(vmp);
return(tll_islocked(&vmp->m_lock) || tll_haspendinglock(&vmp->m_lock));
}
/*===========================================================================*
* lock_vmnt *
*===========================================================================*/
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int lock_vmnt(struct vmnt *vmp, tll_access_t locktype)
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{
int r;
tll_access_t initial_locktype;
ASSERTVMP(vmp);
initial_locktype = (locktype == VMNT_EXCL) ? VMNT_WRITE : locktype;
if (vmp->m_fs_e == who_e) return(EDEADLK);
r = tll_lock(&vmp->m_lock, initial_locktype);
if (r == EBUSY) return(r);
if (initial_locktype != locktype) {
tll_upgrade(&vmp->m_lock);
}
#if LOCK_DEBUG
if (locktype == VMNT_READ)
fp->fp_vmnt_rdlocks++;
#endif
return(OK);
}
/*===========================================================================*
* vmnt_unmap_by_endpoint *
*===========================================================================*/
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void vmnt_unmap_by_endpt(endpoint_t proc_e)
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{
struct vmnt *vmp;
if ((vmp = find_vmnt(proc_e)) != NULL) {
mark_vmnt_free(vmp);
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fs_cancel(vmp);
invalidate_filp_by_endpt(proc_e);
if (vmp->m_mounted_on) {
/* Only put mount point when it was actually used as mount
* point. That is, the mount was succesful. */
put_vnode(vmp->m_mounted_on);
}
}
}
/*===========================================================================*
* unlock_vmnt *
*===========================================================================*/
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void unlock_vmnt(struct vmnt *vmp)
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{
ASSERTVMP(vmp);
#if LOCK_DEBUG
/* Decrease read-only lock counter when not locked as VMNT_WRITE or
* VMNT_EXCL */
if (!tll_locked_by_me(&vmp->m_lock))
fp->fp_vmnt_rdlocks--;
#endif
tll_unlock(&vmp->m_lock);
#if LOCK_DEBUG
assert(!tll_locked_by_me(&vmp->m_lock));
#endif
}