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minix/servers/vfs/mount.c
Ben Gras fd7ef243e4 cleanup of vfs shutdown logic; makes clean unmounts easier (but 
needs checking if fp_wd or fp_rd is NULL before use)
2009-04-29 16:59:18 +00:00

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/* This file performs the MOUNT and UMOUNT system calls.
*
* The entry points into this file are
* do_mount: perform the MOUNT system call
* do_umount: perform the UMOUNT system call
*
* Changes for VFS:
* Jul 2006 (Balazs Gerofi)
*/
#include "fs.h"
#include <fcntl.h>
#include <string.h>
#include <minix/callnr.h>
#include <minix/com.h>
#include <minix/keymap.h>
#include <minix/const.h>
#include <minix/endpoint.h>
#include <minix/syslib.h>
#include <unistd.h>
#include <sys/stat.h>
#include <dirent.h>
#include "file.h"
#include "fproc.h"
#include "param.h"
#include <minix/vfsif.h>
#include "vnode.h"
#include "vmnt.h"
/* Allow the root to be replaced before the first 'real' mount. */
PRIVATE int allow_newroot = 1;
FORWARD _PROTOTYPE( dev_t name_to_dev, (void) );
FORWARD _PROTOTYPE( int mount_fs, (endpoint_t fs_e) );
/*===========================================================================*
* do_fslogin *
*===========================================================================*/
PUBLIC int do_fslogin()
{
/* Login before mount request */
if ((unsigned long)mount_m_in.m1_p3 != who_e) {
last_login_fs_e = who_e;
return SUSPEND;
}
/* Login after a suspended mount */
else {
/* Copy back original mount request message */
m_in = mount_m_in;
/* Set up last login FS */
last_login_fs_e = who_e;
/* Set up endpoint and call nr */
who_e = m_in.m_source;
who_p = _ENDPOINT_P(who_e);
call_nr = m_in.m_type;
fp = &fproc[who_p]; /* pointer to proc table struct */
super_user = (fp->fp_effuid == SU_UID ? TRUE : FALSE); /* su? */
return do_mount();
}
}
/*===========================================================================*
* do_mount *
*===========================================================================*/
PUBLIC int do_mount()
{
endpoint_t fs_e;
CHECK_VREFS;
/* Only the super-user may do MOUNT. */
if (!super_user) return(EPERM);
/* FS process' endpoint number */
fs_e = (unsigned long)m_in.m1_p3;
/* Sanity check on process number. */
if(fs_e <= 0) {
printf("vfs: warning: got process number %d for mount call.\n", fs_e);
return EINVAL;
}
/* Do the actual job */
return mount_fs(fs_e);
}
/*===========================================================================*
* mount *
*===========================================================================*/
PRIVATE int mount_fs(endpoint_t fs_e)
{
/* Perform the mount(name, mfile, rd_only) system call. */
int rdir, mdir; /* TRUE iff {root|mount} file is dir */
int i, r, found, isroot, replace_root;
struct fproc *tfp;
struct dmap *dp;
dev_t dev;
message m;
struct vnode *root_node, *mounted_on, *bspec;
struct vmnt *vmp;
char *label;
struct node_details res;
CHECK_VREFS;
/* Only the super-user may do MOUNT. */
if (!super_user) return(EPERM);
/* If FS not yet logged in, save message and suspend mount */
if (last_login_fs_e != fs_e) {
mount_m_in = m_in;
return SUSPEND;
}
/* Mount request got after FS login or
* FS login arrived after a suspended mount */
last_login_fs_e = NONE;
/* Clear endpoint field */
mount_m_in.m1_p3 = (char *) NONE;
/* If 'name' is not for a block special file, return error. */
if (fetch_name(m_in.name1, m_in.name1_length, M1) != OK) return(err_code);
/* Convert name to device number */
if ((dev = name_to_dev()) == NO_DEV) return(err_code);
/* Check whether there is a block special file open which uses the
* same device (partition) */
for (bspec = &vnode[0]; bspec < &vnode[NR_VNODES]; ++bspec) {
if (bspec->v_ref_count > 0 && bspec->v_sdev == dev) {
/* Found, sync the buffer cache */
req_sync(bspec->v_fs_e);
break;
/* Note: there are probably some blocks in the FS process' buffer
* cache which contain data on this minor, although they will be
* purged since the handling moves to the new FS process (if
* everything goes well with the mount...)
*/
}
}
/* Didn't find? */
if (bspec == &vnode[NR_VNODES] && bspec->v_sdev != dev)
bspec = NULL;
/* Scan vmnt table to see if dev already mounted, if not,
* find a free slot.*/
found = FALSE;
vmp = NIL_VMNT;
for (i = 0; i < NR_MNTS; ++i) {
if (vmnt[i].m_dev == dev) {
vmp = &vmnt[i];
found = TRUE;
break;
}
else if (!vmp && vmnt[i].m_dev == NO_DEV) {
vmp = &vmnt[i];
}
}
/* Partition was/is already mounted */
if (found) {
/* It is possible that we have an old root lying around that
* needs to be remounted. */
if (vmp->m_mounted_on || vmp->m_mounted_on == fproc[FS_PROC_NR].fp_rd) {
/* Normally, m_mounted_on refers to the mount point. For a
* root filesystem, m_mounted_on is equal to the root vnode.
* We assume that the root of FS is always the real root. If
* the two vnodes are different or if the root of FS is equal
* to the root of the filesystem we found, we found a
* filesystem that is in use.
*/
return EBUSY; /* already mounted */
}
if(vmp->m_mounted_on)
panic("vfs", "root unexpectedly mounted somewhere", NO_NUM);
if (root_dev == vmp->m_dev)
panic("fs", "inconsistency remounting old root", NO_NUM);
/* Now get the inode of the file to be mounted on. */
if (fetch_name(m_in.name2, m_in.name2_length, M1) != OK) {
return(err_code);
}
/* Request lookup */
r = lookup_vp(0 /*flags*/, 0 /*!use_realuid*/, &mounted_on);
if (r != OK) return r;
if (mounted_on->v_ref_count != 1)
{
put_vnode(mounted_on);
printf("vfs:mount_fs: mount point is busy\n");
return EBUSY;
}
/* Issue mountpoint request */
r = req_mountpoint(mounted_on->v_fs_e, mounted_on->v_inode_nr);
if (r != OK)
{
put_vnode(mounted_on);
printf("vfs:mount_fs: req_mountpoint_s failed with %d\n", r);
return r;
}
/* Get the root inode of the mounted file system. */
root_node = vmp->m_root_node;
/* File types may not conflict. */
if (r == OK) {
mdir = ((mounted_on->v_mode & I_TYPE) == I_DIRECTORY);
/* TRUE iff dir */
rdir = ((root_node->v_mode & I_TYPE) == I_DIRECTORY);
if (!mdir && rdir) r = EISDIR;
}
/* If error, return the mount point. */
if (r != OK) {
put_vnode(mounted_on);
return(r);
}
/* Nothing else can go wrong. Perform the mount. */
vmp->m_mounted_on = mounted_on;
vmp->m_flags = m_in.rd_only;
allow_newroot = 0; /* The root is now fixed */
return(OK);
}
/* Fetch the name of the mountpoint */
if (fetch_name(m_in.name2, m_in.name2_length, M1) != OK) {
return(err_code);
}
isroot= (strcmp(user_fullpath, "/") == 0);
replace_root= (isroot && allow_newroot);
if (!replace_root)
{
/* Get mount point and inform the FS it is on. */
#if 0
printf("vfs:mount_fs: mount point at '%s'\n", user_fullpath);
#endif
r = lookup_vp(0 /*flags*/, 0 /*!use_realuid*/, &mounted_on);
if (r != OK)
return r;
/* Issue mountpoint request */
r = req_mountpoint(mounted_on->v_fs_e, mounted_on->v_inode_nr);
if (r != OK) {
put_vnode(mounted_on);
printf("vfs:mount_fs: req_mountpoint_s failed with %d\n", r);
return r;
}
}
/* We'll need a vnode for the root inode, check whether there is one */
if ((root_node = get_free_vnode(__FILE__, __LINE__)) == NIL_VNODE) {
printf("VFSmount: no free vnode available\n");
return ENFILE;
}
/* Get driver process' endpoint */
dp = &dmap[(dev >> MAJOR) & BYTE];
if (dp->dmap_driver == NONE) {
printf("VFSmount: no driver for dev %x\n", dev);
return(EINVAL);
}
label= dp->dmap_label;
if (strlen(label) == 0)
{
panic(__FILE__, "vfs:mount_fs: no label for major", dev >> MAJOR);
}
#if 0
printf("vfs:mount_fs: label = '%s'\n", label);
#endif
/* Issue request */
r = req_readsuper(fs_e, label, dev, m_in.rd_only, isroot, &res);
if (r != OK) {
put_vnode(mounted_on);
return r;
}
/* Fill in root node's fields */
root_node->v_fs_e = res.fs_e;
root_node->v_inode_nr = res.inode_nr;
root_node->v_mode = res.fmode;
root_node->v_uid = res.uid;
root_node->v_gid = res.gid;
root_node->v_size = res.fsize;
root_node->v_sdev = NO_DEV;
root_node->v_fs_count = 1;
root_node->v_ref_count = 1;
/* Fill in max file size and blocksize for the vmnt */
vmp->m_fs_e = res.fs_e;
vmp->m_dev = dev;
vmp->m_flags = m_in.rd_only;
/* Root node is indeed on the partition */
root_node->v_vmnt = vmp;
root_node->v_dev = vmp->m_dev;
if (replace_root) {
/* Superblock and root node already read.
* Nothing else can go wrong. Perform the mount. */
vmp->m_root_node = root_node;
vmp->m_mounted_on = NULL;
root_dev = dev;
ROOT_FS_E = fs_e;
/* Replace all root and working directories */
for (i= 0, tfp= fproc; i<NR_PROCS; i++, tfp++) {
if (tfp->fp_pid == PID_FREE)
continue;
#define MAKEROOT(what) { \
put_vnode(what); \
dup_vnode(root_node); \
what = root_node; \
}
if(tfp->fp_rd) MAKEROOT(tfp->fp_rd);
if(tfp->fp_wd) MAKEROOT(tfp->fp_wd);
}
CHECK_VREFS;
return(OK);
}
/* File types may not conflict. */
if (r == OK) {
mdir = ((mounted_on->v_mode & I_TYPE) == I_DIRECTORY);/* TRUE iff dir */
rdir = ((root_node->v_mode & I_TYPE) == I_DIRECTORY);
if (!mdir && rdir) r = EISDIR;
}
/* If error, return the super block and both inodes; release the vmnt. */
if (r != OK) {
put_vnode(mounted_on);
put_vnode(root_node);
vmp->m_dev = NO_DEV;
return(r);
}
/* Nothing else can go wrong. Perform the mount. */
vmp->m_mounted_on = mounted_on;
vmp->m_root_node = root_node;
/* The root is now fixed */
allow_newroot = 0;
/* There was a block spec file open, and it should be handled by the
* new FS proc now */
if (bspec) {
printf("VFSmount: moving opened block spec to new FS_e: %d...\n", fs_e);
bspec->v_bfs_e = fs_e;
}
CHECK_VREFS;
return(OK);
}
/*===========================================================================*
* do_umount *
*===========================================================================*/
PUBLIC int do_umount()
{
/* Perform the umount(name) system call. */
dev_t dev;
CHECK_VREFS;
/* Only the super-user may do UMOUNT. */
if (!super_user) return(EPERM);
CHECK_VREFS;
/* If 'name' is not for a block special file, return error. */
if (fetch_name(m_in.name, m_in.name_length, M3) != OK) return(err_code);
CHECK_VREFS;
if ( (dev = name_to_dev()) == NO_DEV) return(err_code);
CHECK_VREFS;
return(unmount(dev));
}
/*===========================================================================*
* unmount *
*===========================================================================*/
PUBLIC int unmount(dev)
Dev_t dev;
{
struct vnode *vp, *vi;
struct vmnt *vmp_i = NULL, *vmp = NULL;
struct dmap *dp;
int count, r;
int fs_e;
CHECK_VREFS;
/* Find vmnt */
for (vmp_i = &vmnt[0]; vmp_i < &vmnt[NR_MNTS]; ++vmp_i) {
if (vmp_i->m_dev == dev) {
if(vmp) panic(__FILE__, "device mounted more than once", dev);
vmp = vmp_i;
}
}
/* Device mounted? */
if(!vmp)
return EINVAL;
/* See if the mounted device is busy. Only 1 vnode using it should be
* open -- the root vnode -- and that inode only 1 time.
*/
count = 0;
for (vp = &vnode[0]; vp < &vnode[NR_VNODES]; vp++) {
if (vp->v_ref_count > 0 && vp->v_dev == dev) {
#if 0
int i;
struct fproc *tfp;
printf("unmount: vnode 0x%x/%d in use %d times\n",
dev, vp->v_inode_nr, vp->v_ref_count);
for (i= 0, tfp= fproc; i<NR_PROCS; i++, tfp++) {
int n;
if (tfp->fp_pid == PID_FREE)
continue;
if(tfp->fp_wd == vp)
printf("\tvnode %d: wd of pid %d\n",
vp->v_inode_nr, tfp->fp_pid);
if(tfp->fp_rd == vp)
printf("\tvnode %d: rd of pid %d\n",
vp->v_inode_nr, tfp->fp_pid);
for(n = 0; n < OPEN_MAX; n++) {
if(tfp->fp_filp[n] && tfp->fp_filp[n]->filp_vno == vp)
printf("\tvnode %d: fd %d of pid %d\n",
vp->v_inode_nr, n, tfp->fp_pid);
}
}
for (vmp_i = &vmnt[0]; vmp_i < &vmnt[NR_MNTS]; ++vmp_i) {
if (vmp_i->m_dev != NO_DEV) {
if(vmp_i->m_mounted_on == vp) {
printf("\tvnode %d: is a mount point\n",
vp->v_inode_nr);
}
#if 1
if(vmp_i->m_root_node == vp) {
printf("\tvnode %d: is a root node\n",
vp->v_inode_nr);
}
#endif
}
}
#endif
count += vp->v_ref_count;
}
}
CHECK_VREFS;
if (count > 1) {
return(EBUSY); /* can't umount a busy file system */
}
CHECK_VREFS;
vnode_clean_refs(vmp->m_root_node);
CHECK_VREFS;
if (vmp->m_mounted_on) {
put_vnode(vmp->m_mounted_on);
vmp->m_mounted_on->v_fs_count--;
vmp->m_mounted_on = NIL_VNODE;
}
put_vnode(vmp->m_root_node);
vmp->m_root_node->v_ref_count = 0;
vmp->m_root_node = NIL_VNODE;
/* Request FS the unmount */
if(vmp->m_fs_e <= 0 || vmp->m_fs_e == NONE)
panic(__FILE__, "unmount: strange fs endpoint", vmp->m_fs_e);
if ((r = req_unmount(vmp->m_fs_e)) != OK) {
/* Not recoverable. */
printf("VFS: ignoring unmount failure %d from %d\n", r, vmp->m_fs_e);
}
vmp->m_dev = NO_DEV;
vmp->m_fs_e = NONE;
CHECK_VREFS;
/* Is there a block special file that was handled by that partition? */
for (vp = &vnode[0]; vp < &vnode[NR_VNODES]; vp++) {
if ((vp->v_mode & I_TYPE) == I_BLOCK_SPECIAL &&
vp->v_bfs_e == vmp->m_fs_e) {
/* Get the driver endpoint of the block spec device */
dp = &dmap[(dev >> MAJOR) & BYTE];
if (dp->dmap_driver == NONE) {
printf("VFSblock_spec_open: driver not found for device %d\n",
dev);
/* What should be done, panic??? */
continue;
}
printf("VFSunmount: moving block spec %d to root FS\n", dev);
vp->v_bfs_e = ROOT_FS_E;
/* Send the driver endpoint (even if it is known already...) */
if ((r = req_newdriver(vp->v_bfs_e, vp->v_sdev, dp->dmap_driver))
!= OK) {
printf("VFSunmount: error sending driver endpoint for block spec\n");
}
}
}
CHECK_VREFS;
return(OK);
}
/*===========================================================================*
* name_to_dev *
*===========================================================================*/
PRIVATE dev_t name_to_dev()
{
/* Convert the block special file 'path' to a device number. If 'path'
* is not a block special file, return error code in 'err_code'. */
int r;
dev_t dev;
struct vnode *vp;
/* Request lookup */
if ((r = lookup_vp(0 /*flags*/, 0 /*!use_realuid*/, &vp)) != OK) {
printf("vfs: name_to_dev: lookup of '%s' failed\n", user_fullpath);
return NO_DEV;
}
if ((vp->v_mode & I_TYPE) != I_BLOCK_SPECIAL) {
err_code = ENOTBLK;
dev= NO_DEV;
}
else
dev= vp->v_sdev;
put_vnode(vp);
return dev;
}
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