220 lines
6.3 KiB
C
220 lines
6.3 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_mount: perform the MOUNT system call
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* do_umount: perform the UMOUNT system call
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*/
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#include "fs.h"
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#include <fcntl.h>
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#include <minix/com.h>
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#include <sys/stat.h>
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#include "buf.h"
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#include "file.h"
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#include "fproc.h"
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#include "inode.h"
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#include "param.h"
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#include "super.h"
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FORWARD _PROTOTYPE( dev_t name_to_dev, (char *path) );
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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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/* Perform the mount(name, mfile, rd_only) system call. */
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register struct inode *rip, *root_ip;
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struct super_block *xp, *sp;
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dev_t dev;
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mode_t bits;
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int rdir, mdir; /* TRUE iff {root|mount} file is dir */
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int r, found;
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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 '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) return(err_code);
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if ( (dev = name_to_dev(user_path)) == NO_DEV) return(err_code);
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/* Scan super block table to see if dev already mounted & find a free slot.*/
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sp = NIL_SUPER;
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found = FALSE;
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for (xp = &super_block[0]; xp < &super_block[NR_SUPERS]; xp++) {
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if (xp->s_dev == dev) found = TRUE; /* is it mounted already? */
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if (xp->s_dev == NO_DEV) sp = xp; /* record free slot */
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}
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if (found) return(EBUSY); /* already mounted */
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if (sp == NIL_SUPER) return(ENFILE); /* no super block available */
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/* Open the device the file system lives on. */
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if (dev_open(dev, who, m_in.rd_only ? R_BIT : (R_BIT|W_BIT)) != OK)
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return(EINVAL);
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/* Make the cache forget about blocks it has open on the filesystem */
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(void) do_sync();
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invalidate(dev);
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/* Fill in the super block. */
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sp->s_dev = dev; /* read_super() needs to know which dev */
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r = read_super(sp);
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/* Is it recognized as a Minix filesystem? */
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if (r != OK) {
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dev_close(dev);
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sp->s_dev = NO_DEV;
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return(r);
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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) {
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dev_close(dev);
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sp->s_dev = NO_DEV;
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return(err_code);
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}
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if ( (rip = eat_path(user_path)) == NIL_INODE) {
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dev_close(dev);
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sp->s_dev = NO_DEV;
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return(err_code);
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}
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/* It may not be busy. */
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r = OK;
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if (rip->i_count > 1) r = EBUSY;
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/* It may not be special. */
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bits = rip->i_mode & I_TYPE;
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if (bits == I_BLOCK_SPECIAL || bits == I_CHAR_SPECIAL) r = ENOTDIR;
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/* Get the root inode of the mounted file system. */
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root_ip = NIL_INODE; /* if 'r' not OK, make sure this is defined */
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if (r == OK) {
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if ( (root_ip = get_inode(dev, ROOT_INODE)) == NIL_INODE) r = err_code;
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}
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if (root_ip != NIL_INODE && root_ip->i_mode == 0) {
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r = EINVAL;
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}
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/* File types of 'rip' and 'root_ip' may not conflict. */
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if (r == OK) {
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mdir = ((rip->i_mode & I_TYPE) == I_DIRECTORY); /* TRUE iff dir */
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rdir = ((root_ip->i_mode & I_TYPE) == I_DIRECTORY);
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if (!mdir && rdir) r = EISDIR;
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}
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/* If error, return the super block and both inodes; release the maps. */
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if (r != OK) {
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put_inode(rip);
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put_inode(root_ip);
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(void) do_sync();
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invalidate(dev);
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dev_close(dev);
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sp->s_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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rip->i_mount = I_MOUNT; /* this bit says the inode is mounted on */
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sp->s_imount = rip;
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sp->s_isup = root_ip;
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sp->s_rd_only = m_in.rd_only;
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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()
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{
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/* Perform the umount(name) system call. */
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dev_t dev;
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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, 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(user_path)) == NO_DEV) return(err_code);
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return(unmount(dev));
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}
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/*===========================================================================*
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* unmount *
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*===========================================================================*/
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PUBLIC int unmount(dev)
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Dev_t dev;
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{
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/* Unmount a file system by device number. */
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register struct inode *rip;
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struct super_block *sp, *sp1;
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int count;
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/* See if the mounted device is busy. Only 1 inode using it should be
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* open -- the root inode -- and that inode only 1 time.
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*/
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count = 0;
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for (rip = &inode[0]; rip< &inode[NR_INODES]; rip++)
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if (rip->i_count > 0 && rip->i_dev == dev) count += rip->i_count;
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if (count > 1) return(EBUSY); /* can't umount a busy file system */
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/* Find the super block. */
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sp = NIL_SUPER;
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for (sp1 = &super_block[0]; sp1 < &super_block[NR_SUPERS]; sp1++) {
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if (sp1->s_dev == dev) {
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sp = sp1;
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break;
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}
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}
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/* Sync the disk, and invalidate cache. */
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(void) do_sync(); /* force any cached blocks out of memory */
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invalidate(dev); /* invalidate cache entries for this dev */
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if (sp == NIL_SUPER) {
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return(EINVAL);
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}
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/* Close the device the file system lives on. */
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dev_close(dev);
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/* Finish off the unmount. */
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sp->s_imount->i_mount = NO_MOUNT; /* inode returns to normal */
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put_inode(sp->s_imount); /* release the inode mounted on */
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put_inode(sp->s_isup); /* release the root inode of the mounted fs */
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sp->s_imount = NIL_INODE;
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sp->s_dev = NO_DEV;
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return(OK);
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}
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/*===========================================================================*
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* name_to_dev *
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*===========================================================================*/
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PRIVATE dev_t name_to_dev(path)
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char *path; /* pointer to path name */
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{
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/* Convert the block special file 'path' to a device number. If 'path'
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* is not a block special file, return error code in 'err_code'.
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*/
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register struct inode *rip;
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register dev_t dev;
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/* If 'path' can't be opened, give up immediately. */
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if ( (rip = eat_path(path)) == NIL_INODE) return(NO_DEV);
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/* If 'path' is not a block special file, return error. */
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if ( (rip->i_mode & I_TYPE) != I_BLOCK_SPECIAL) {
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err_code = ENOTBLK;
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put_inode(rip);
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return(NO_DEV);
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}
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/* Extract the device number. */
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dev = (dev_t) rip->i_zone[0];
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put_inode(rip);
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return(dev);
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}
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