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minix/servers/vfs/mount.c
Ben Gras 41e9fedf87 Mostly bugfixes of bugs triggered by the test set. 
bugfixes:
 SYSTEM:
 . removed
        rc->p_priv->s_flags = 0;
   for the priv struct shared by all user processes in get_priv(). this
   should only be done once. doing a SYS_PRIV_USER in sys_privctl()
   caused the flags of all user processes to be reset, so they were no
   longer PREEMPTIBLE. this happened when RS executed a policy script.
   (this broke test1 in the test set)

 VFS/MFS:
 . chown can change the mode of a file, and chmod arguments are only
   part of the full file mode so the full filemode is slightly magic.
   changed these calls so that the final modes are returned to VFS, so
   that the vnode can be kept up-to-date.
   (this broke test11 in the test set)

 MFS:
 . lookup() checked for sizeof(string) instead of sizeof(user_path),
   truncating long path names
   (caught by test 23)
 . truncate functions neglected to update ctime
   (this broke test16)

 VFS:
 . corner case of an empty filename lookup caused fields of a request
   not to be filled in in the lookup functions, not making it clear
   that the lookup had failed, causing messages to garbage processes,
   causing strange failures.
   (caught by test 30)
 . trust v_size in vnode when doing reads or writes on non-special
   files, truncating i/o where necessary; this is necessary for pipes,
   as MFS can't tell when a pipe has been truncated without it being
   told explicitly each time.
   when the last reader/writer on a pipe closes, tell FS about
   the new size using truncate_vn().
   (this broke test 25, among others)
 . permission check for chdir() had disappeared; added a
   forbidden() call
   (caught by test 23)

new code, shouldn't change anything:
 . introduced RTS_SET, RTS_UNSET, and RTS_ISSET macro's, and their
   LOCK variants. These macros set and clear the p_rts_flags field,
   causing a lot of duplicated logic like

       old_flags = rp->p_rts_flags;            /* save value of the flags */
       rp->p_rts_flags &= ~NO_PRIV;
       if (old_flags != 0 && rp->p_rts_flags == 0) lock_enqueue(rp);

   to change into the simpler

       RTS_LOCK_UNSET(rp, NO_PRIV);

   so the macros take care of calling dequeue() and enqueue() (or lock_*()),
   as the case may be). This makes the code a bit more readable and a
   bit less fragile.
 . removed return code from do_clocktick in CLOCK as it currently
   never replies
 . removed some debug code from VFS
 . fixed grant debug message in device.c
 
preemptive checks, tests, changes:
 . added return code checks of receive() to SYSTEM and CLOCK
 . O_TRUNC should never arrive at MFS (added sanity check and removed
   O_TRUNC code)
 . user_path declared with PATH_MAX+1 to let it be null-terminated
 . checks in MFS to see if strings passed by VFS are null-terminated
 
 IS:
 . static irq name table thrown out
2007-02-01 17:50:02 +00:00

580 lines
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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;
/* 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;
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;
node_req_t node_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;
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);
/* Get free vnode for the mountpoint */
if ((mounted_on = get_free_vnode(__FILE__, __LINE__)) == 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_ref_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_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_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_ref_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_fs_count = 1;
mounted_on->v_ref_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(__FILE__, __LINE__)) == 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_ref_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);
}
/* 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 superblock error dev: %d\n", dev);
dev_close(dev);
return r;
}
/* Fill in request message fields.*/
node_req.fs_e = sres.fs_e;
node_req.inode_nr = sres.inode_nr;
/* Issue request */
if ((r = req_getnode(&node_req, &res)) != OK)
{
printf("mount: req_getnode failed: %d\n", r);
dev_close(dev);
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 = 2;
root_node->v_ref_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;
root_node->v_ref_count++;
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_fs_count = 1;
mounted_on->v_ref_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_i = NULL, *vmp = NULL;
struct dmap *dp;
int count, r;
int fs_e;
/* 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) {
count += vp->v_ref_count;
}
}
if (count > 1) {
return(EBUSY); /* can't umount a busy file system */
}
vnode_clean_refs(vmp->m_root_node);
/* Request FS the unmount */
if(vmp->m_fs_e <= 0)
panic(__FILE__, "unmount: strange fs endpoint", vmp->m_fs_e);
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_ref_count = 0;
}
else {
vmp->m_mounted_on->v_fs_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 = NONE;
vmp->m_driver_e = NONE;
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;
}
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