minix/servers/vfs/mount.c

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/* This file performs the MOUNT and UMOUNT system calls.
*
* The entry points into this file are
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* do_fsready: perform the FS_READY system call
* do_mount: perform the MOUNT system call
* do_umount: perform the UMOUNT system call
* unmount: unmount a file system
*/
#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 <minix/bitmap.h>
#include <minix/ds.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/mount.h>
#include <dirent.h>
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#include <assert.h>
#include "file.h"
#include "fproc.h"
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#include "dmap.h"
#include <minix/vfsif.h>
#include "vnode.h"
#include "vmnt.h"
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#include "path.h"
#include "param.h"
/* Allow the root to be replaced before the first 'real' mount. */
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static int have_root = 0;
/* Bitmap of in-use "none" pseudo devices. */
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static bitchunk_t nonedev[BITMAP_CHUNKS(NR_NONEDEVS)] = { 0 };
#define alloc_nonedev(dev) SET_BIT(nonedev, minor(dev) - 1)
#define free_nonedev(dev) UNSET_BIT(nonedev, minor(dev) - 1)
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static dev_t name_to_dev(int allow_mountpt, char path[PATH_MAX]);
static dev_t find_free_nonedev(void);
static void update_bspec(dev_t dev, endpoint_t fs_e, int send_drv_e);
/*===========================================================================*
* update_bspec *
*===========================================================================*/
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static void update_bspec(dev_t dev, endpoint_t fs_e, int send_drv_e)
{
/* Update all block special files for a certain device, to use a new FS endpt
* to route raw block I/O requests through.
*/
struct vnode *vp;
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struct dmap *dp;
int r, major;
for (vp = &vnode[0]; vp < &vnode[NR_VNODES]; ++vp)
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if (vp->v_ref_count > 0 && S_ISBLK(vp->v_mode) && vp->v_sdev == dev) {
vp->v_bfs_e = fs_e;
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if (send_drv_e) {
major = major(dev);
if (major < 0 || major >= NR_DEVICES) {
/* Can't update for out-of-range major */
continue;
}
dp = &dmap[major(dev)];
if (dp->dmap_driver == NONE) {
/* Can't update for vanished driver */
printf("VFS: can't send new driver label\n");
continue;
}
if ((r = req_newdriver(fs_e, vp->v_sdev,
dp->dmap_label)) != OK) {
printf("VFS: Failed to send new driver label"
" for moved block special file to %d\n",
fs_e);
}
}
}
}
/*===========================================================================*
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* do_fsready *
*===========================================================================*/
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int do_fsready()
{
/* deprecated */
return(SUSPEND);
}
/*===========================================================================*
* do_mount *
*===========================================================================*/
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int do_mount()
{
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/* Perform the mount(name, mfile, mount_flags) system call. */
Driver refactory for live update and crash recovery. SYSLIB CHANGES: - DS calls to publish / retrieve labels consider endpoints instead of u32_t. VFS CHANGES: - mapdriver() only adds an entry in the dmap table in VFS. - dev_up() is only executed upon reception of a driver up event. INET CHANGES: - INET no longer searches for existing drivers instances at startup. - A newtwork driver is (re)initialized upon reception of a driver up event. - Networking startup is now race-free by design. No need to waste 5 seconds at startup any more. DRIVER CHANGES: - Every driver publishes driver up events when starting for the first time or in case of restart when recovery actions must be taken in the upper layers. - Driver up events are published by drivers through DS. - For regular drivers, VFS is normally the only subscriber, but not necessarily. For instance, when the filter driver is in use, it must subscribe to driver up events to initiate recovery. - For network drivers, inet is the only subscriber for now. - Every VFS driver is statically linked with libdriver, every network driver is statically linked with libnetdriver. DRIVER LIBRARIES CHANGES: - Libdriver is extended to provide generic receive() and ds_publish() interfaces for VFS drivers. - driver_receive() is a wrapper for sef_receive() also used in driver_task() to discard spurious messages that were meant to be delivered to a previous version of the driver. - driver_receive_mq() is the same as driver_receive() but integrates support for queued messages. - driver_announce() publishes a driver up event for VFS drivers and marks the driver as initialized and expecting a DEV_OPEN message. - Libnetdriver is introduced to provide similar receive() and ds_publish() interfaces for network drivers (netdriver_announce() and netdriver_receive()). - Network drivers all support live update with no state transfer now. KERNEL CHANGES: - Added kernel call statectl for state management. Used by driver_announce() to unblock eventual callers sendrecing to the driver.
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endpoint_t fs_e;
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int r, slot, rdonly, nodev;
char fullpath[PATH_MAX];
char mount_label[LABEL_MAX];
dev_t dev;
int mflags;
vir_bytes label, vname1, vname2;
size_t vname1_length, vname2_length;
mflags = job_m_in.mount_flags;
label = (vir_bytes) job_m_in.fs_label;
vname1 = (vir_bytes) job_m_in.name1;
vname1_length = (size_t) job_m_in.name1_length;
vname2 = (vir_bytes) job_m_in.name2;
vname2_length = (size_t) job_m_in.name2_length;
/* Only the super-user may do MOUNT. */
if (!super_user) return(EPERM);
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/* FS process' endpoint number */
if (mflags & MS_LABEL16) {
/* Get the label from the caller, and ask DS for the endpoint. */
r = sys_datacopy(who_e, label, SELF, (vir_bytes) mount_label,
sizeof(mount_label));
if (r != OK) return(r);
mount_label[sizeof(mount_label)-1] = 0;
Driver refactory for live update and crash recovery. SYSLIB CHANGES: - DS calls to publish / retrieve labels consider endpoints instead of u32_t. VFS CHANGES: - mapdriver() only adds an entry in the dmap table in VFS. - dev_up() is only executed upon reception of a driver up event. INET CHANGES: - INET no longer searches for existing drivers instances at startup. - A newtwork driver is (re)initialized upon reception of a driver up event. - Networking startup is now race-free by design. No need to waste 5 seconds at startup any more. DRIVER CHANGES: - Every driver publishes driver up events when starting for the first time or in case of restart when recovery actions must be taken in the upper layers. - Driver up events are published by drivers through DS. - For regular drivers, VFS is normally the only subscriber, but not necessarily. For instance, when the filter driver is in use, it must subscribe to driver up events to initiate recovery. - For network drivers, inet is the only subscriber for now. - Every VFS driver is statically linked with libdriver, every network driver is statically linked with libnetdriver. DRIVER LIBRARIES CHANGES: - Libdriver is extended to provide generic receive() and ds_publish() interfaces for VFS drivers. - driver_receive() is a wrapper for sef_receive() also used in driver_task() to discard spurious messages that were meant to be delivered to a previous version of the driver. - driver_receive_mq() is the same as driver_receive() but integrates support for queued messages. - driver_announce() publishes a driver up event for VFS drivers and marks the driver as initialized and expecting a DEV_OPEN message. - Libnetdriver is introduced to provide similar receive() and ds_publish() interfaces for network drivers (netdriver_announce() and netdriver_receive()). - Network drivers all support live update with no state transfer now. KERNEL CHANGES: - Added kernel call statectl for state management. Used by driver_announce() to unblock eventual callers sendrecing to the driver.
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r = ds_retrieve_label_endpt(mount_label, &fs_e);
if (r != OK) return(r);
} else {
/* Legacy support: get the endpoint from the request itself. */
fs_e = (endpoint_t) label;
mount_label[0] = 0;
}
/* Sanity check on process number. */
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if (isokendpt(fs_e, &slot) != OK) return(EINVAL);
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/* Should the file system be mounted read-only? */
rdonly = (mflags & MS_RDONLY);
/* A null string for block special device means don't use a device at all. */
nodev = (vname1_length == 0);
if (!nodev) {
/* If 'name' is not for a block special file, return error. */
if (fetch_name(vname1, vname1_length, fullpath) != OK)
return(err_code);
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if ((dev = name_to_dev(FALSE /*allow_mountpt*/, fullpath)) == NO_DEV)
return(err_code);
} else {
/* Find a free pseudo-device as substitute for an actual device. */
if ((dev = find_free_nonedev()) == NO_DEV)
return(err_code);
}
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/* Fetch the name of the mountpoint */
if (fetch_name(vname2, vname2_length, fullpath) != OK) return(err_code);
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/* Do the actual job */
return mount_fs(dev, fullpath, fs_e, rdonly, mount_label);
}
/*===========================================================================*
* mount_fs *
*===========================================================================*/
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int mount_fs(
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dev_t dev,
char mountpoint[PATH_MAX],
endpoint_t fs_e,
int rdonly,
char mount_label[LABEL_MAX] )
{
int rdir, mdir; /* TRUE iff {root|mount} file is dir */
int i, r = OK, found, isroot, mount_root, con_reqs, slot;
struct fproc *tfp, *rfp;
struct dmap *dp;
struct vnode *root_node, *vp = NULL;
struct vmnt *new_vmp, *parent_vmp;
char *label;
struct node_details res;
struct lookup resolve;
/* Look up block device driver label when dev is not a pseudo-device */
label = "";
if (!is_nonedev(dev)) {
/* Get driver process' endpoint */
dp = &dmap[major(dev)];
if (dp->dmap_driver == NONE) {
printf("VFS: no driver for dev %d\n", dev);
return(EINVAL);
}
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label = dp->dmap_label;
assert(strlen(label) > 0);
}
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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;
for (i = 0; i < NR_MNTS; ++i) {
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if (vmnt[i].m_dev == dev) found = TRUE;
}
if (found) {
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return(EBUSY);
} else if ((new_vmp = get_free_vmnt()) == NULL) {
return(ENOMEM);
}
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if ((r = lock_vmnt(new_vmp, VMNT_EXCL)) != OK) return(r);
isroot = (strcmp(mountpoint, "/") == 0);
mount_root = (isroot && have_root < 2); /* Root can be mounted twice:
* 1: ramdisk
* 2: boot disk (e.g., harddisk)
*/
if (!mount_root) {
/* Get vnode of mountpoint */
lookup_init(&resolve, mountpoint, PATH_NOFLAGS, &parent_vmp, &vp);
resolve.l_vmnt_lock = VMNT_EXCL;
resolve.l_vnode_lock = VNODE_WRITE;
if ((vp = eat_path(&resolve, fp)) == NULL)
r = err_code;
else if (vp->v_ref_count == 1) {
/*Tell FS on which vnode it is mounted (glue into mount tree)*/
r = req_mountpoint(vp->v_fs_e, vp->v_inode_nr);
} else
r = EBUSY;
if (vp != NULL) {
/* Quickly unlock to allow back calls (from e.g. FUSE) to
* relock */
unlock_vmnt(parent_vmp);
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}
if (r != OK) {
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if (vp != NULL) {
unlock_vnode(vp);
put_vnode(vp);
}
unlock_vmnt(new_vmp);
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return(r);
}
}
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/* We'll need a vnode for the root inode */
if ((root_node = get_free_vnode()) == NULL) {
if (vp != NULL) {
unlock_vnode(vp);
put_vnode(vp);
}
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unlock_vmnt(new_vmp);
return(err_code);
}
lock_vnode(root_node, VNODE_OPCL);
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/* Record process as a system process */
if (isokendpt(fs_e, &slot) != OK) {
if (vp != NULL) {
unlock_vnode(vp);
put_vnode(vp);
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}
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unlock_vnode(root_node);
unlock_vmnt(new_vmp);
return(EINVAL);
}
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rfp = &fproc[slot];
rfp->fp_flags |= FP_SYS_PROC; /* Process is an FS */
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/* Store some essential vmnt data first */
new_vmp->m_fs_e = fs_e;
new_vmp->m_dev = dev;
if (rdonly) new_vmp->m_flags |= VMNT_READONLY;
else new_vmp->m_flags &= ~VMNT_READONLY;
/* Tell FS which device to mount */
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new_vmp->m_flags |= VMNT_MOUNTING;
r = req_readsuper(fs_e, label, dev, rdonly, isroot, &res, &con_reqs);
new_vmp->m_flags &= ~VMNT_MOUNTING;
if (r != OK) {
mark_vmnt_free(new_vmp);
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unlock_vnode(root_node);
if (vp != NULL) {
unlock_vnode(vp);
put_vnode(vp);
}
unlock_vmnt(new_vmp);
return(r);
}
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lock_bsf();
/* 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;
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root_node->v_fs_count = 1;
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root_node->v_ref_count = 1;
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/* Root node is indeed on the partition */
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root_node->v_vmnt = new_vmp;
root_node->v_dev = new_vmp->m_dev;
if (con_reqs == 0)
new_vmp->m_comm.c_max_reqs = 1; /* Default if FS doesn't tell us */
else
new_vmp->m_comm.c_max_reqs = con_reqs;
new_vmp->m_comm.c_cur_reqs = 0;
if (mount_root) {
/* Superblock and root node already read.
* Nothing else can go wrong. Perform the mount. */
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new_vmp->m_root_node = root_node;
new_vmp->m_mounted_on = NULL;
strcpy(new_vmp->m_label, mount_label);
if (is_nonedev(dev)) alloc_nonedev(dev);
update_bspec(dev, fs_e, 0 /* Don't send new driver endpoint */);
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ROOT_DEV = dev;
ROOT_FS_E = fs_e;
/* Replace all root and working directories */
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for (i = 0, tfp = fproc; i < NR_PROCS; i++, tfp++) {
if (tfp->fp_pid == PID_FREE)
continue;
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#define MAKEROOT(what) { \
if (what) put_vnode(what); \
dup_vnode(root_node); \
what = root_node; \
}
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MAKEROOT(tfp->fp_rd);
MAKEROOT(tfp->fp_wd);
}
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unlock_vnode(root_node);
unlock_vmnt(new_vmp);
have_root++; /* We have a (new) root */
unlock_bsf();
return(OK);
}
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/* File types may not conflict. */
mdir = ((vp->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) {
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unlock_vnode(vp);
unlock_vnode(root_node);
mark_vmnt_free(new_vmp);
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unlock_vmnt(new_vmp);
put_vnode(vp);
put_vnode(root_node);
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unlock_bsf();
return(r);
}
/* Nothing else can go wrong. Perform the mount. */
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new_vmp->m_mounted_on = vp;
new_vmp->m_root_node = root_node;
strcpy(new_vmp->m_label, mount_label);
/* Allocate the pseudo device that was found, if not using a real device. */
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if (is_nonedev(dev)) alloc_nonedev(dev);
/* The new FS will handle block I/O requests for its device now. */
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if (!(new_vmp->m_flags & VMNT_FORCEROOTBSF))
update_bspec(dev, fs_e, 0 /* Don't send new driver endpoint */);
unlock_vnode(vp);
unlock_vnode(root_node);
unlock_vmnt(new_vmp);
unlock_bsf();
return(OK);
}
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/*===========================================================================*
* mount_pfs *
*===========================================================================*/
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void mount_pfs(void)
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{
/* Mount the Pipe File Server. It's not really mounted onto the file system,
but it's necessary it has a vmnt entry to make locking easier */
dev_t dev;
struct vmnt *vmp;
struct fproc *rfp;
if ((dev = find_free_nonedev()) == NO_DEV)
panic("VFS: no nonedev to initialize PFS");
if ((vmp = get_free_vmnt()) == NULL)
panic("VFS: no vmnt to initialize PFS");
alloc_nonedev(dev);
vmp->m_dev = dev;
vmp->m_fs_e = PFS_PROC_NR;
strcpy(vmp->m_label, "pfs");
rfp = &fproc[_ENDPOINT_P(PFS_PROC_NR)];
rfp->fp_flags |= FP_SYS_PROC; /* PFS is a driver and an FS */
}
/*===========================================================================*
* do_umount *
*===========================================================================*/
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int do_umount(void)
{
/* Perform the umount(name) system call.
* syscall might provide 'name' embedded in the message.
*/
char label[LABEL_MAX];
dev_t dev;
int r;
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char fullpath[PATH_MAX];
vir_bytes vname;
size_t vname_length;
vname = (vir_bytes) job_m_in.name;
vname_length = (size_t) job_m_in.name_length;
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/* Only the super-user may do umount. */
if (!super_user) return(EPERM);
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/* If 'name' is not for a block special file or mountpoint, return error. */
if (copy_name(vname_length, fullpath) != OK) {
/* Direct copy failed, try fetching from user space */
if (fetch_name(vname, vname_length, fullpath) != OK)
return(err_code);
}
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if ((dev = name_to_dev(TRUE /*allow_mountpt*/, fullpath)) == NO_DEV)
return(err_code);
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if ((r = unmount(dev, label)) != OK) return(r);
/* Return the label of the mounted file system, so that the caller
* can shut down the corresponding server process.
*/
if (strlen(label) >= M3_LONG_STRING) /* should never evaluate to true */
label[M3_LONG_STRING-1] = 0;
strcpy(m_out.umount_label, label);
return(OK);
}
/*===========================================================================*
* unmount *
*===========================================================================*/
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int unmount(
dev_t dev, /* block-special device */
char *label /* buffer to retrieve label, or NULL */
)
{
struct vnode *vp;
struct vmnt *vmp_i = NULL, *vmp = NULL;
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int count, locks, r;
/* Find vmnt that is to be unmounted */
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for (vmp_i = &vmnt[0]; vmp_i < &vmnt[NR_MNTS]; ++vmp_i) {
if (vmp_i->m_dev == dev) {
if(vmp) panic("device mounted more than once: %d", dev);
vmp = vmp_i;
}
}
/* Did we find the vmnt (i.e., was dev a mounted device)? */
if(!vmp) return(EINVAL);
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if ((r = lock_vmnt(vmp, VMNT_EXCL)) != OK) return(r);
/* See if the mounted device is busy. Only 1 vnode using it should be
* open -- the root vnode -- and that inode only 1 time. */
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locks = 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 (is_vnode_locked(vp)) locks++;
}
if (count > 1 || locks > 1 || tll_haspendinglock(&vmp->m_lock)) {
unlock_vmnt(vmp);
return(EBUSY); /* can't umount a busy file system */
}
/* Tell FS to drop all inode references for root inode except 1. */
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vnode_clean_refs(vmp->m_root_node);
if (vmp->m_mounted_on) {
put_vnode(vmp->m_mounted_on);
vmp->m_mounted_on = NULL;
}
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vmp->m_comm.c_max_reqs = 1; /* Force max concurrent reqs to just one, so
* we won't send any messages after the
* unmount request */
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/* Tell FS to unmount */
if ((r = req_unmount(vmp->m_fs_e)) != OK) /* Not recoverable. */
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printf("VFS: ignoring failed umount attempt FS endpoint: %d (%d)\n",
vmp->m_fs_e, r);
if (is_nonedev(vmp->m_dev)) free_nonedev(vmp->m_dev);
if (label != NULL) strcpy(label, vmp->m_label);
if (vmp->m_root_node) { /* PFS lacks a root node */
vmp->m_root_node->v_ref_count = 0;
vmp->m_root_node->v_fs_count = 0;
vmp->m_root_node->v_sdev = NO_DEV;
vmp->m_root_node = NULL;
}
mark_vmnt_free(vmp);
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unlock_vmnt(vmp);
/* The root FS will handle block I/O requests for this device now. */
lock_bsf();
update_bspec(dev, ROOT_FS_E, 1 /* send new driver endpoint */);
unlock_bsf();
return(OK);
}
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/*===========================================================================*
* unmount_all *
*===========================================================================*/
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void unmount_all(void)
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{
/* Unmount all filesystems. File systems are mounted on other file systems,
* so you have to pull off the loose bits repeatedly to get it all undone.
*/
int i;
struct vmnt *vmp;
/* Now unmount the rest */
for (i = 0; i < NR_MNTS; i++) {
/* Unmount at least one. */
for (vmp = &vmnt[0]; vmp < &vmnt[NR_MNTS]; vmp++) {
if (vmp->m_dev != NO_DEV)
unmount(vmp->m_dev, NULL);
}
}
check_vnode_locks();
check_vmnt_locks();
check_filp_locks();
check_bsf_lock();
}
/*===========================================================================*
* name_to_dev *
*===========================================================================*/
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static dev_t name_to_dev(int allow_mountpt, char path[PATH_MAX])
{
/* 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'.
*/
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dev_t dev;
struct vnode *vp;
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struct vmnt *vmp;
struct lookup resolve;
lookup_init(&resolve, path, PATH_NOFLAGS, &vmp, &vp);
resolve.l_vmnt_lock = VMNT_READ;
resolve.l_vnode_lock = VNODE_READ;
/* Request lookup */
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if ((vp = eat_path(&resolve, fp)) == 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 {
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err_code = ENOTBLK;
dev = NO_DEV;
}
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unlock_vnode(vp);
unlock_vmnt(vmp);
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put_vnode(vp);
return(dev);
}
/*===========================================================================*
* is_nonedev *
*===========================================================================*/
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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 *
*===========================================================================*/
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static 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;
}