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phunix/servers/vfs/mount.c

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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 fs_exit, (endpoint_t fs_e) );
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;
printf("VFS: FS_e %d logged in\n", last_login_fs_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? */
printf("VFS: FS_e %d logged in. Mount WAKEN UP\n", (unsigned int)m_in.m1_p3);
return do_mount();
}
}
/*===========================================================================*
* do_mount *
*===========================================================================*/
PUBLIC int do_mount()
{
endpoint_t fs_e;
int r;
/* FS process' endpoint number */
fs_e = (unsigned long)m_in.m1_p3;
/* Do the actual job */
r = mount_fs(fs_e);
/* If not OK and not suspended, bring down FS proc.. */
if (r != OK && r != SUSPEND) {
/* Ask RS to bring down FS */
if (-1 == fs_exit(fs_e)) {
printf("VFSmount: WARNING: couldn't stop FS endp: %d\n", fs_e);
}
}
return r;
}
/*===========================================================================*
* 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;
struct fproc *tfp;
struct dmap *dp;
dev_t dev;
message m;
struct vnode *vp, *root_node, *mounted_on, *bspec;
struct vmnt *vmp, *vmp2;
struct mountpoint_req mreq;
struct node_details res;
struct readsuper_req sreq;
struct readsuper_res sres;
struct lookup_req lookup_req;
/* 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;
printf("VFS: FS_e %d not yet logged in. Mount SUSPENDED\n", fs_e);
return SUSPEND;
}
/* Mount request got after FS login or
* FS login arrived after a suspended mount */
last_login_fs_e = 0;
/* Clear endpoint field */
mount_m_in.m1_p3 = 0;
/* 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);
/* Get free vnode for the mountpoint */
if ((mounted_on = get_free_vnode()) == NIL_VNODE) {
printf("VFSmount: not free vnode available\n");
return ENFILE;
}
/* Mark it as used so that we won't find the same for the root_node */
mounted_on->v_count = 1;
/* 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_count > 0 && bspec->v_sdev == dev) {
/* Found, sync the buffer cache */
printf("VFSmount: minor is opened as a block spec file, sync cache...\n");
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_root_node ||
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 two the
* root of the filesystem we found, we found a filesystem that
* is in use. */
mounted_on->v_count = 0;
return EBUSY; /* already mounted */
}
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);
}
/* Fill in lookup request fields */
lookup_req.path = user_fullpath;
lookup_req.lastc = NULL;
lookup_req.flags = EAT_PATH;
/* Request lookup */
if ((r = lookup(&lookup_req, &res)) != OK) return r;
/* Fill in request message fields.*/
mreq.fs_e = res.fs_e;
mreq.inode_nr = res.inode_nr;
mreq.uid = fp->fp_effuid;
mreq.gid = fp->fp_effgid;
/* Issue request */
if ((r = req_mountpoint(&mreq, &res)) != OK) return r;
mounted_on->v_fs_e = res.fs_e;
mounted_on->v_inode_nr = res.inode_nr;
mounted_on->v_mode = res.fmode;
mounted_on->v_size = res.fsize;
mounted_on->v_sdev = NO_DEV;
mounted_on->v_count = 1;
/* Find the vmnt for the vnode */
if ( (vmp2 = find_vmnt(mounted_on->v_fs_e)) == NIL_VMNT)
printf("VFS: vmnt not found by mount()\n");
mounted_on->v_vmnt = vmp2;
mounted_on->v_dev = vmp2->m_dev;
/* 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. */
put_vnode(vmp->m_mounted_on);
vmp->m_mounted_on = mounted_on;
vmp->m_flags = m_in.rd_only;
allow_newroot = 0; /* The root is now fixed */
return(OK);
}
/* We'll need a vnode for the root inode, check whether there is one */
if ((root_node = get_free_vnode()) == NIL_VNODE) {
printf("VFSmount: no free vnode available\n");
return ENFILE;
}
/* Set it back to zero so that if st goes wrong it won't be kept in use */
mounted_on->v_count = 0;
/* Fetch the name of the mountpoint */
if (fetch_name(m_in.name2, m_in.name2_length, M1) != OK) {
return(err_code);
}
/* 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);
}
/* Open the device the file system lives on. */
if (dev_open(dev, fs_e, m_in.rd_only ? R_BIT : (R_BIT|W_BIT)) != OK) {
return(EINVAL);
}
printf("VFSmount: FS_e: %d mp: %s D_e: %d\n", fs_e, user_fullpath,
dp->dmap_driver);
/* Request for reading superblock and root inode */
sreq.fs_e = fs_e;
sreq.readonly = m_in.rd_only;
sreq.boottime = boottime;
sreq.driver_e = dp->dmap_driver;
sreq.dev = dev;
sreq.slink_storage = user_fullpath;
if (!strcmp(user_fullpath, "/")) sreq.isroot = 1;
else sreq.isroot = 0;
/* Issue request */
if ((r = req_readsuper(&sreq, &sres)) != OK) {
printf("VFSmount: reading superb error dev: %d\n", dev);
dev_close(dev);
return r;
}
/* Fill in root node's fields */
root_node->v_fs_e = sres.fs_e;
root_node->v_inode_nr = sres.inode_nr;
root_node->v_mode = sres.fmode;
root_node->v_size = sres.fsize;
root_node->v_sdev = NO_DEV;
root_node->v_count = 1;
/* Fill in max file size and blocksize for the vmnt */
vmp->m_fs_e = sres.fs_e;
vmp->m_dev = dev;
vmp->m_block_size = sres.blocksize;
vmp->m_max_file_size = sres.maxsize;
vmp->m_flags = m_in.rd_only;
vmp->m_driver_e = dp->dmap_driver;
/* Root node is indeed on the partition */
root_node->v_vmnt = vmp;
root_node->v_dev = vmp->m_dev;
if (strcmp(user_fullpath, "/") == 0 && allow_newroot) {
printf("Replacing root\n");
/* Superblock and root node already read.
* Nothing else can go wrong. Perform the mount. */
vmp->m_root_node = root_node;
vmp->m_mounted_on = root_node;
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;
if (tfp->fp_rd == NULL)
panic("fs", "do_mount: null rootdir", i);
put_vnode(tfp->fp_rd);
dup_vnode(root_node);
tfp->fp_rd = root_node;
if (tfp->fp_wd == NULL)
panic("fs", "do_mount: null workdir", i);
put_vnode(tfp->fp_wd);
dup_vnode(root_node);
tfp->fp_wd = root_node;
}
return(OK);
}
/* Fill in lookup request fields */
lookup_req.path = user_fullpath;
lookup_req.lastc = NULL;
lookup_req.flags = EAT_PATH;
/* Request lookup */
if ((r = lookup(&lookup_req, &res)) != OK) {
put_vnode(root_node);
return r;
}
/* Fill in request fields.*/
mreq.fs_e = res.fs_e;
mreq.inode_nr = res.inode_nr;
mreq.uid = fp->fp_effuid;
mreq.gid = fp->fp_effgid;
/* Issue request */
if ((r = req_mountpoint(&mreq, &res)) != OK) {
put_vnode(root_node);
return r;
}
/* Fill in vnode's fields */
mounted_on->v_fs_e = res.fs_e;
mounted_on->v_inode_nr = res.inode_nr;
mounted_on->v_mode = res.fmode;
mounted_on->v_size = res.fsize;
mounted_on->v_sdev = NO_DEV;
mounted_on->v_count = 1;
/* Find the vmnt for the vnode */
if ( (vmp2 = find_vmnt(mounted_on->v_fs_e)) == NIL_VMNT)
printf("VFS: vmnt not found by mount()");
mounted_on->v_vmnt = vmp2;
mounted_on->v_dev = vmp2->m_dev;
/* 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;
dev_close(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;
}
return(OK);
}
/*===========================================================================*
* do_umount *
*===========================================================================*/
PUBLIC int do_umount()
{
/* Perform the umount(name) system call. */
dev_t dev;
/* Only the super-user may do UMOUNT. */
if (!super_user) return(EPERM);
/* 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);
if ( (dev = name_to_dev()) == NO_DEV) return(err_code);
return(unmount(dev));
}
/*===========================================================================*
* unmount *
*===========================================================================*/
PUBLIC int unmount(dev)
Dev_t dev;
{
struct vnode *vp;
struct vmnt *vmp;
struct dmap *dp;
int count, r;
int fs_e;
/* Find vmnt */
for (vmp = &vmnt[0]; vmp < &vmnt[NR_MNTS]; ++vmp) {
if (vmp->m_dev == dev) break;
else if (vmp == &vmnt[NR_MNTS])
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_count > 0 && vp->v_dev == dev) {
count += vp->v_count;
}
}
if (count > 1) {
printf("VFSunmount: %d filesystem is busy count: %d\n", dev, count);
return(EBUSY); /* can't umount a busy file system */
}
/* Request FS the unmount */
if ((r = req_unmount(vmp->m_fs_e)) != OK) return r;
/* Close the device the file system lives on. */
dev_close(dev);
/* 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;
vp->v_blocksize = _MIN_BLOCK_SIZE;
/* 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");
}
}
}
/* Root device is mounted on itself */
if (vmp->m_root_node != vmp->m_mounted_on) {
put_vnode(vmp->m_mounted_on);
vmp->m_root_node->v_count = 0;
}
else {
vmp->m_mounted_on->v_count--;
}
fs_e = vmp->m_fs_e;
vmp->m_root_node = NIL_VNODE;
vmp->m_mounted_on = NIL_VNODE;
vmp->m_dev = NO_DEV;
vmp->m_fs_e = 0;
vmp->m_driver_e = 0;
/* Ask RS to bring down FS */
if (-1 == fs_exit(fs_e)) {
printf("VFSunmount: WARNING: couldn't stop FS endp: %d\n", fs_e);
}
printf("VFSunmount: DEV: %d unmounted\n", dev);
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'. */
struct lookup_req lookup_req;
struct node_details res;
int r;
/* Fill in lookup request fields */
lookup_req.path = user_fullpath;
lookup_req.lastc = NULL;
lookup_req.flags = EAT_PATH;
/* Request lookup */
if ((r = lookup(&lookup_req, &res)) != OK) return r;
if ((res.fmode & I_TYPE) != I_BLOCK_SPECIAL) {
err_code = ENOTBLK;
return NO_DEV;
}
return res.dev;
}
/*===========================================================================*
* fs_exit *
*===========================================================================*/
PRIVATE int fs_exit(fs_e)
endpoint_t fs_e;
{
/* Build a message for stoping a FS server and ask RS to do it */
message m;
pid_t fs_pid;
int r;
/* Don't need to stop the one in the bootimage */
if (fs_e == MFS_PROC_NR) return OK;
/* Get pid for this endpoint */
if (-1 == (fs_pid = getnpid(fs_e))) {
printf("VFS: couldn't find pid for fs_e: %d\n", fs_e);
return -1;
}
printf("VFSfs_exit: Bringing down FS endp: %d (pid: %d)\n", fs_e, fs_pid);
/* Ask RS to stop process */
m.RS_PID = fs_pid;
if (OK != (r = _taskcall(RS_PROC_NR, RS_DOWN, &m))) {
printf("VFSfs_exit: couldn't bring FS down pid: %d\n", fs_pid);
return -1;
}
return OK;
}
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