(this avoids data structure confusion if a mountpoint is reused as a mountpoint until that's properly fixed.)
553 lines
16 KiB
C
553 lines
16 KiB
C
/* This file performs the MOUNT and UMOUNT system calls.
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*
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* The entry points into this file are
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* do_fslogin: perform the FSLOGIN system call
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* do_mount: perform the MOUNT system call
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* do_umount: perform the UMOUNT system call
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* unmount: unmount a file system
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*/
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#include "fs.h"
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#include <fcntl.h>
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#include <string.h>
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#include <minix/callnr.h>
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#include <minix/com.h>
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#include <minix/keymap.h>
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#include <minix/const.h>
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#include <minix/endpoint.h>
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#include <minix/syslib.h>
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#include <minix/bitmap.h>
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#include <minix/ds.h>
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#include <unistd.h>
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#include <sys/stat.h>
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#include <sys/mount.h>
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#include <dirent.h>
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#include "file.h"
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#include "fproc.h"
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#include "param.h"
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#include <minix/vfsif.h>
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#include "vnode.h"
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#include "vmnt.h"
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/* Allow the root to be replaced before the first 'real' mount. */
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PRIVATE int allow_newroot = 1;
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/* Bitmap of in-use "none" pseudo devices. */
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PRIVATE bitchunk_t nonedev[BITMAP_CHUNKS(NR_NONEDEVS)] = { 0 };
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#define alloc_nonedev(dev) SET_BIT(nonedev, minor(dev) - 1)
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#define free_nonedev(dev) UNSET_BIT(nonedev, minor(dev) - 1)
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FORWARD _PROTOTYPE( dev_t name_to_dev, (int allow_mountpt) );
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FORWARD _PROTOTYPE( int mount_fs, (endpoint_t fs_e) );
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FORWARD _PROTOTYPE( int is_nonedev, (dev_t dev) );
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FORWARD _PROTOTYPE( dev_t find_free_nonedev, (void) );
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/*===========================================================================*
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* do_fslogin *
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*===========================================================================*/
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PUBLIC int do_fslogin()
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{
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int r;
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/* Login before mount request */
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if (mount_fs_e != who_e) {
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last_login_fs_e = who_e;
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r = SUSPEND;
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}
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/* Login after a suspended mount */
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else {
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/* Copy back original mount request message */
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m_in = mount_m_in;
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/* Set up last login FS */
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last_login_fs_e = who_e;
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/* Set up endpoint and call nr */
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who_e = m_in.m_source;
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who_p = _ENDPOINT_P(who_e);
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call_nr = m_in.m_type;
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fp = &fproc[who_p]; /* pointer to proc table struct */
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super_user = (fp->fp_effuid == SU_UID ? TRUE : FALSE); /* su? */
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r = mount_fs(mount_fs_e);
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}
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return(r);
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}
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/*===========================================================================*
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* do_mount *
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*===========================================================================*/
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PUBLIC int do_mount()
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{
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endpoint_t fs_e;
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int r, proc_nr;
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/* Only the super-user may do MOUNT. */
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if (!super_user) return(EPERM);
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/* FS process' endpoint number */
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if (m_in.mount_flags & MS_LABEL16) {
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/* Get the label from the caller, and ask DS for the endpoint. */
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r = sys_datacopy(who_e, (vir_bytes) m_in.fs_label, SELF,
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(vir_bytes) mount_label, (phys_bytes) sizeof(mount_label));
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if (r != OK) return(r);
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mount_label[sizeof(mount_label)-1] = 0;
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r = ds_retrieve_label_endpt(mount_label, &fs_e);
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if (r != OK) return(r);
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if (isokendpt(fs_e, &proc_nr) != OK) return(EINVAL);
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} else {
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/* Legacy support: get the endpoint from the request itself. */
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fs_e = (endpoint_t) m_in.fs_label;
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mount_label[0] = 0;
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}
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/* Sanity check on process number. */
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if(fs_e <= 0) {
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printf("VFS: warning: got process number %d for mount call.\n", fs_e);
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return EINVAL;
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}
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/* Do the actual job */
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return mount_fs(fs_e);
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}
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/*===========================================================================*
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* mount *
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*===========================================================================*/
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PRIVATE int mount_fs(endpoint_t fs_e)
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{
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/* Perform the mount(name, mfile, mount_flags) system call. */
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int rdir, mdir; /* TRUE iff {root|mount} file is dir */
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int i, r, found, rdonly, nodev, isroot, replace_root;
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struct fproc *tfp;
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struct dmap *dp;
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dev_t dev;
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struct vnode *root_node, *vp = NULL, *bspec;
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struct vmnt *vmp;
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char *label;
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struct node_details res;
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/* Only the super-user may do MOUNT. */
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if (!super_user) return(EPERM);
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/* If FS not yet logged in, save message and suspend mount */
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if (last_login_fs_e != fs_e) {
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mount_m_in = m_in;
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mount_fs_e = fs_e;
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/* mount_label is already saved */
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return(SUSPEND);
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}
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/* Mount request got after FS login or FS login arrived after a suspended
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* mount.
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*/
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last_login_fs_e = NONE;
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/* Clear endpoint field */
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mount_fs_e = NONE;
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/* Should the file system be mounted read-only? */
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rdonly = (m_in.mount_flags & MS_RDONLY);
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/* A null string for block special device means don't use a device at all. */
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nodev = (m_in.name1_length == 0);
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if (!nodev) {
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/* If 'name' is not for a block special file, return error. */
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if (fetch_name(m_in.name1, m_in.name1_length, M1) != OK)
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return(err_code);
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if ((dev = name_to_dev(FALSE /*allow_mountpt*/)) == NO_DEV)
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return(err_code);
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} else {
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/* Find a free pseudo-device as substitute for an actual device. */
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if ((dev = find_free_nonedev()) == NO_DEV)
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return(err_code);
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}
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/* Check whether there is a block special file open which uses the
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* same device (partition) */
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for (bspec = &vnode[0]; bspec < &vnode[NR_VNODES]; ++bspec) {
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if (bspec->v_ref_count > 0 && bspec->v_sdev == dev) {
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/* Found, sync the buffer cache */
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req_sync(bspec->v_fs_e);
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break;
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/* Note: there are probably some blocks in the FS process'
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* buffer cache which contain data on this minor, although
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* they will be purged since the handling moves to the new
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* FS process (if everything goes well with the mount...)
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*/
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}
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}
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/* Didn't find? */
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if (bspec == &vnode[NR_VNODES] && bspec->v_sdev != dev)
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bspec = NULL;
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/* Scan vmnt table to see if dev already mounted. If not, find a free slot.*/
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found = FALSE;
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vmp = NULL;
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for (i = 0; i < NR_MNTS; ++i) {
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if (vmnt[i].m_dev == dev) {
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vmp = &vmnt[i];
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found = TRUE;
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break;
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} else if (!vmp && vmnt[i].m_dev == NO_DEV) {
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vmp = &vmnt[i];
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}
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}
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/* Partition was/is already mounted */
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if (found) {
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/* It is possible that we have an old root lying around that
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* needs to be remounted. This could for example be a boot
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* ramdisk that has already been replaced by the real root.
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*/
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if(vmp->m_mounted_on || root_dev == vmp->m_dev) {
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return(EBUSY); /* not a root or still mounted */
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}
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/* Now get the inode of the file to be mounted on. */
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if (fetch_name(m_in.name2, m_in.name2_length, M1)!=OK) return(err_code);
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if ((vp = eat_path(PATH_NOFLAGS)) == NULL) return(err_code);
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if (vp->v_ref_count != 1) {
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put_vnode(vp);
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return(EBUSY);
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}
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/* Tell FS on which vnode it is mounted (glue into mount tree) */
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if ((r = req_mountpoint(vp->v_fs_e, vp->v_inode_nr)) == OK) {
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root_node = vmp->m_root_node;
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/* File types of 'vp' and 'root_node' may not conflict. */
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mdir = ((vp->v_mode & I_TYPE) == I_DIRECTORY);/* TRUE iff dir*/
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rdir = ((root_node->v_mode & I_TYPE) == I_DIRECTORY);
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if(!mdir && rdir) r = EISDIR;
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}
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if (r != OK) {
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put_vnode(vp);
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return(r);
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}
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/* Nothing else can go wrong. Perform the mount. */
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vmp->m_mounted_on = vp;
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vmp->m_flags = rdonly;
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strcpy(vmp->m_label, mount_label);
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allow_newroot = 0; /* The root is now fixed */
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if (nodev) alloc_nonedev(dev); /* Make the allocation final */
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return(OK);
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}
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/* Fetch the name of the mountpoint */
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if (fetch_name(m_in.name2, m_in.name2_length, M1) != OK) return(err_code);
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isroot = (strcmp(user_fullpath, "/") == 0);
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replace_root = (isroot && allow_newroot);
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if(!replace_root) {
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/* Get vnode of mountpoint */
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if ((vp = eat_path(PATH_NOFLAGS)) == NULL) return(err_code);
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if (vp->v_ref_count != 1) {
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put_vnode(vp);
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return(EBUSY);
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}
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/* Tell FS on which vnode it is mounted (glue into mount tree) */
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if ((r = req_mountpoint(vp->v_fs_e, vp->v_inode_nr)) != OK) {
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put_vnode(vp);
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return r;
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}
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}
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/* We'll need a vnode for the root inode, check whether there is one */
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if ((root_node = get_free_vnode()) == NULL) {
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if (vp != NULL) put_vnode(vp);
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return(ENFILE);
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}
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label = "";
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if (!nodev) {
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/* Get driver process' endpoint */
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dp = &dmap[(dev >> MAJOR) & BYTE];
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if (dp->dmap_driver == NONE) {
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printf("VFS: no driver for dev %x\n", dev);
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if (vp != NULL) put_vnode(vp);
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return(EINVAL);
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}
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label = dp->dmap_label;
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if (strlen(label) == 0)
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panic("VFS mount_fs: no label for major: 0x%x", dev >> MAJOR);
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}
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/* Tell FS which device to mount */
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if ((r = req_readsuper(fs_e, label, dev, rdonly, isroot, &res)) != OK) {
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if (vp != NULL) put_vnode(vp);
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return(r);
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}
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/* Fill in root node's fields */
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root_node->v_fs_e = res.fs_e;
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root_node->v_inode_nr = res.inode_nr;
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root_node->v_mode = res.fmode;
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root_node->v_uid = res.uid;
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root_node->v_gid = res.gid;
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root_node->v_size = res.fsize;
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root_node->v_sdev = NO_DEV;
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root_node->v_fs_count = 1;
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root_node->v_ref_count = 1;
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/* Fill in max file size and blocksize for the vmnt */
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vmp->m_fs_e = res.fs_e;
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vmp->m_dev = dev;
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vmp->m_flags = rdonly;
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/* Root node is indeed on the partition */
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root_node->v_vmnt = vmp;
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root_node->v_dev = vmp->m_dev;
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if(replace_root) {
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/* Superblock and root node already read.
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* Nothing else can go wrong. Perform the mount. */
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vmp->m_root_node = root_node;
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vmp->m_mounted_on = NULL;
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strcpy(vmp->m_label, mount_label);
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if (nodev) alloc_nonedev(dev);
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root_dev = dev;
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ROOT_FS_E = fs_e;
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/* Replace all root and working directories */
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for (i= 0, tfp= fproc; i<NR_PROCS; i++, tfp++) {
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if (tfp->fp_pid == PID_FREE)
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continue;
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#define MAKEROOT(what) { \
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put_vnode(what); \
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dup_vnode(root_node); \
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what = root_node; \
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}
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if(tfp->fp_rd) MAKEROOT(tfp->fp_rd);
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if(tfp->fp_wd) MAKEROOT(tfp->fp_wd);
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}
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return(OK);
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}
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/* File types may not conflict. */
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mdir = ((vp->v_mode & I_TYPE) == I_DIRECTORY); /*TRUE iff dir*/
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rdir = ((root_node->v_mode & I_TYPE) == I_DIRECTORY);
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if (!mdir && rdir) r = EISDIR;
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/* If error, return the super block and both inodes; release the vmnt. */
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if (r != OK) {
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put_vnode(vp);
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put_vnode(root_node);
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vmp->m_dev = NO_DEV;
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return(r);
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}
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/* Nothing else can go wrong. Perform the mount. */
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vmp->m_mounted_on = vp;
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vmp->m_root_node = root_node;
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strcpy(vmp->m_label, mount_label);
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/* The root is now fixed */
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allow_newroot = 0;
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/* Allocate the pseudo device that was found, if not using a real device. */
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if (nodev) alloc_nonedev(dev);
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/* There was a block spec file open, and it should be handled by the
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* new FS proc now */
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if (bspec) bspec->v_bfs_e = fs_e;
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return(OK);
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}
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/*===========================================================================*
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* do_umount *
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*===========================================================================*/
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PUBLIC int do_umount(void)
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{
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/* Perform the umount(name) system call. */
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char label[LABEL_MAX];
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dev_t dev;
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int r;
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/* Only the super-user may do umount. */
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if (!super_user) return(EPERM);
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/* If 'name' is not for a block special file or mountpoint, return error. */
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if(fetch_name(m_in.name, m_in.name_length, M3) != OK) return(err_code);
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if((dev = name_to_dev(TRUE /*allow_mountpt*/)) == NO_DEV) return(err_code);
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if((r = unmount(dev, label)) != OK) return(r);
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/* Return the label of the mounted file system, so that the caller
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* can shut down the corresponding server process.
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*/
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if (strlen(label) >= M3_LONG_STRING) /* should never evaluate to true */
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label[M3_LONG_STRING-1] = 0;
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strcpy(m_out.umount_label, label);
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return(OK);
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}
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/*===========================================================================*
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* unmount *
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*===========================================================================*/
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PUBLIC int unmount(
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dev_t dev, /* block-special device */
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char *label /* buffer to retrieve label, or NULL */
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)
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{
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struct vnode *vp;
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struct vmnt *vmp_i = NULL, *vmp = NULL;
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struct dmap *dp;
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int count, r;
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/* Find vmnt that is to be unmounted */
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for(vmp_i = &vmnt[0]; vmp_i < &vmnt[NR_MNTS]; ++vmp_i) {
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if (vmp_i->m_dev == dev) {
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if(vmp) panic("device mounted more than once: %d", dev);
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vmp = vmp_i;
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}
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}
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/* Did we find the vmnt (i.e., was dev a mounted device)? */
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if(!vmp) return(EINVAL);
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/* See if the mounted device is busy. Only 1 vnode using it should be
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* open -- the root vnode -- and that inode only 1 time. */
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count = 0;
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for(vp = &vnode[0]; vp < &vnode[NR_VNODES]; vp++)
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if(vp->v_ref_count > 0 && vp->v_dev == dev) count += vp->v_ref_count;
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if(count > 1) return(EBUSY); /* can't umount a busy file system */
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/* Tell FS to drop all inode references for root inode except 1. */
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vnode_clean_refs(vmp->m_root_node);
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if (vmp->m_mounted_on) {
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put_vnode(vmp->m_mounted_on);
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vmp->m_mounted_on = NULL;
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}
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/* Tell FS to unmount */
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if(vmp->m_fs_e <= 0 || vmp->m_fs_e == NONE)
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panic("unmount: strange fs endpoint: %d", vmp->m_fs_e);
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if ((r = req_unmount(vmp->m_fs_e)) != OK) /* Not recoverable. */
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printf("VFS: ignoring failed umount attempt (%d)\n", r);
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if (is_nonedev(vmp->m_dev))
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free_nonedev(vmp->m_dev);
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if (label != NULL)
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strcpy(label, vmp->m_label);
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vmp->m_root_node->v_ref_count = 0;
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vmp->m_root_node->v_fs_count = 0;
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vmp->m_root_node->v_sdev = NO_DEV;
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vmp->m_root_node = NULL;
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vmp->m_dev = NO_DEV;
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vmp->m_fs_e = NONE;
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/* Is there a block special file that was handled by that partition? */
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for (vp = &vnode[0]; vp < &vnode[NR_VNODES]; vp++) {
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if((vp->v_mode & I_TYPE)==I_BLOCK_SPECIAL && vp->v_bfs_e==vmp->m_fs_e){
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/* Get the driver endpoint of the block spec device */
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dp = &dmap[(dev >> MAJOR) & BYTE];
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if (dp->dmap_driver == NONE) {
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printf("VFS: driver not found for device %d\n", dev);
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continue;
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}
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printf("VFS: umount moving block spec %d to root FS\n", dev);
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vp->v_bfs_e = ROOT_FS_E;
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/* Send the (potentially new) driver endpoint */
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r = req_newdriver(vp->v_bfs_e, vp->v_sdev, dp->dmap_driver);
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if (r != OK)
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printf("VFS: error sending driver endpoint for"
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" moved block spec\n");
|
|
|
|
}
|
|
}
|
|
|
|
return(OK);
|
|
}
|
|
|
|
|
|
/*===========================================================================*
|
|
* name_to_dev *
|
|
*===========================================================================*/
|
|
PRIVATE dev_t name_to_dev(int allow_mountpt)
|
|
{
|
|
/* Convert the block special file in 'user_fullpath' to a device number.
|
|
* If the given path is not a block special file, but 'allow_mountpt' is set
|
|
* and the path is the root node of a mounted file system, return that device
|
|
* number. In all other cases, return NO_DEV and an error code in 'err_code'.
|
|
*/
|
|
dev_t dev;
|
|
struct vnode *vp;
|
|
|
|
/* Request lookup */
|
|
if ((vp = eat_path(PATH_NOFLAGS)) == NULL) {
|
|
return(NO_DEV);
|
|
}
|
|
|
|
if ((vp->v_mode & I_TYPE) == I_BLOCK_SPECIAL) {
|
|
dev = vp->v_sdev;
|
|
} else if (allow_mountpt && vp->v_vmnt->m_root_node == vp) {
|
|
dev = vp->v_dev;
|
|
} else {
|
|
err_code = ENOTBLK;
|
|
dev = NO_DEV;
|
|
}
|
|
|
|
put_vnode(vp);
|
|
return(dev);
|
|
}
|
|
|
|
|
|
/*===========================================================================*
|
|
* is_nonedev *
|
|
*===========================================================================*/
|
|
PRIVATE int is_nonedev(dev_t dev)
|
|
{
|
|
/* Return whether the given device is a "none" pseudo device.
|
|
*/
|
|
|
|
return (major(dev) == NONE_MAJOR &&
|
|
minor(dev) > 0 && minor(dev) <= NR_NONEDEVS);
|
|
}
|
|
|
|
|
|
/*===========================================================================*
|
|
* find_free_nonedev *
|
|
*===========================================================================*/
|
|
PRIVATE dev_t find_free_nonedev(void)
|
|
{
|
|
/* Find a free "none" pseudo device. Do not allocate it yet.
|
|
*/
|
|
int i;
|
|
|
|
for (i = 0; i < NR_NONEDEVS; i++)
|
|
if (!GET_BIT(nonedev, i))
|
|
return makedev(NONE_MAJOR, i + 1);
|
|
|
|
err_code = EMFILE;
|
|
return NO_DEV;
|
|
}
|