linprocfs(5): Add rudimentary /proc/<pid>/mountinfo
This is used by some Linux programs using filehandles (r367773) to locate the mountpoint for a given fsid. Differential Revision: https://reviews.freebsd.org/D27136
This commit is contained in:
Conrad Meyer
parent
77eb984147
commit
b1976ea14c
@ -403,24 +403,85 @@ linprocfs_docpuinfo(PFS_FILL_ARGS)
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}
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#endif /* __i386__ || __amd64__ */
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static const char *path_slash_sys = "/sys";
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static const char *fstype_sysfs = "sysfs";
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static int
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_mtab_helper(const struct pfs_node *pn, const struct statfs *sp,
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const char **mntfrom, const char **mntto, const char **fstype)
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{
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/* determine device name */
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*mntfrom = sp->f_mntfromname;
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/* determine mount point */
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*mntto = sp->f_mntonname;
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/* determine fs type */
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*fstype = sp->f_fstypename;
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if (strcmp(*fstype, pn->pn_info->pi_name) == 0)
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*mntfrom = *fstype = "proc";
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else if (strcmp(*fstype, "procfs") == 0)
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return (ECANCELED);
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if (strcmp(*fstype, "autofs") == 0) {
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/*
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* FreeBSD uses eg "map -hosts", whereas Linux
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* expects just "-hosts".
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*/
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if (strncmp(*mntfrom, "map ", 4) == 0)
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*mntfrom += 4;
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}
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if (strcmp(*fstype, "linsysfs") == 0) {
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*mntfrom = path_slash_sys;
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*fstype = fstype_sysfs;
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} else {
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/* For Linux msdosfs is called vfat */
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if (strcmp(*fstype, "msdosfs") == 0)
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*fstype = "vfat";
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}
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return (0);
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}
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static void
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_sbuf_mntoptions_helper(struct sbuf *sb, uint64_t f_flags)
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{
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sbuf_cat(sb, (f_flags & MNT_RDONLY) ? "ro" : "rw");
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#define ADD_OPTION(opt, name) \
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if (f_flags & (opt)) sbuf_cat(sb, "," name);
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ADD_OPTION(MNT_SYNCHRONOUS, "sync");
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ADD_OPTION(MNT_NOEXEC, "noexec");
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ADD_OPTION(MNT_NOSUID, "nosuid");
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ADD_OPTION(MNT_UNION, "union");
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ADD_OPTION(MNT_ASYNC, "async");
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ADD_OPTION(MNT_SUIDDIR, "suiddir");
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ADD_OPTION(MNT_NOSYMFOLLOW, "nosymfollow");
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ADD_OPTION(MNT_NOATIME, "noatime");
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#undef ADD_OPTION
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}
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/*
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* Filler function for proc/mtab
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* Filler function for proc/mtab and proc/<pid>/mounts.
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*
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* This file doesn't exist in Linux' procfs, but is included here so
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* /proc/mtab doesn't exist in Linux' procfs, but is included here so
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* users can symlink /compat/linux/etc/mtab to /proc/mtab
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*/
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static int
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linprocfs_domtab(PFS_FILL_ARGS)
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{
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struct nameidata nd;
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const char *lep;
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char *dlep, *flep, *mntto, *mntfrom, *fstype;
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const char *lep, *mntto, *mntfrom, *fstype;
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char *dlep, *flep;
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size_t lep_len;
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int error;
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struct statfs *buf, *sp;
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size_t count;
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/* resolve symlinks etc. in the emulation tree prefix */
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/*
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* Ideally, this would use the current chroot rather than some
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* hardcoded path.
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*/
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NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, linux_emul_path, td);
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flep = NULL;
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error = namei(&nd);
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@ -442,51 +503,18 @@ linprocfs_domtab(PFS_FILL_ARGS)
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}
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for (sp = buf; count > 0; sp++, count--) {
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/* determine device name */
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mntfrom = sp->f_mntfromname;
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error = _mtab_helper(pn, sp, &mntfrom, &mntto, &fstype);
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if (error != 0) {
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MPASS(error == ECANCELED);
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continue;
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}
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/* determine mount point */
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mntto = sp->f_mntonname;
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if (strncmp(mntto, lep, lep_len) == 0 && mntto[lep_len] == '/')
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mntto += lep_len;
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/* determine fs type */
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fstype = sp->f_fstypename;
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if (strcmp(fstype, pn->pn_info->pi_name) == 0)
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mntfrom = fstype = "proc";
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else if (strcmp(fstype, "procfs") == 0)
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continue;
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if (strcmp(fstype, "autofs") == 0) {
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/*
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* FreeBSD uses eg "map -hosts", whereas Linux
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* expects just "-hosts".
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*/
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if (strncmp(mntfrom, "map ", 4) == 0)
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mntfrom += 4;
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}
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if (strcmp(fstype, "linsysfs") == 0) {
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sbuf_printf(sb, "/sys %s sysfs %s", mntto,
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sp->f_flags & MNT_RDONLY ? "ro" : "rw");
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} else {
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/* For Linux msdosfs is called vfat */
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if (strcmp(fstype, "msdosfs") == 0)
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fstype = "vfat";
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sbuf_printf(sb, "%s %s %s %s", mntfrom, mntto, fstype,
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sp->f_flags & MNT_RDONLY ? "ro" : "rw");
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}
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#define ADD_OPTION(opt, name) \
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if (sp->f_flags & (opt)) sbuf_printf(sb, "," name);
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ADD_OPTION(MNT_SYNCHRONOUS, "sync");
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ADD_OPTION(MNT_NOEXEC, "noexec");
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ADD_OPTION(MNT_NOSUID, "nosuid");
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ADD_OPTION(MNT_UNION, "union");
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ADD_OPTION(MNT_ASYNC, "async");
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ADD_OPTION(MNT_SUIDDIR, "suiddir");
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ADD_OPTION(MNT_NOSYMFOLLOW, "nosymfollow");
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ADD_OPTION(MNT_NOATIME, "noatime");
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#undef ADD_OPTION
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sbuf_printf(sb, "%s %s %s ", mntfrom, mntto, fstype);
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_sbuf_mntoptions_helper(sb, sp->f_flags);
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/* a real Linux mtab will also show NFS options */
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sbuf_printf(sb, " 0 0\n");
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}
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@ -496,6 +524,96 @@ linprocfs_domtab(PFS_FILL_ARGS)
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return (error);
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}
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static int
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linprocfs_doprocmountinfo(PFS_FILL_ARGS)
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{
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struct nameidata nd;
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const char *mntfrom, *mntto, *fstype;
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const char *lep;
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char *dlep, *flep;
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struct statfs *buf, *sp;
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size_t count, lep_len;
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int error;
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/*
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* Ideally, this would use the current chroot rather than some
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* hardcoded path.
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*/
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NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, linux_emul_path, td);
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flep = NULL;
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error = namei(&nd);
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lep = linux_emul_path;
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if (error == 0) {
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if (vn_fullpath(nd.ni_vp, &dlep, &flep) == 0)
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lep = dlep;
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vrele(nd.ni_vp);
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}
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lep_len = strlen(lep);
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buf = NULL;
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error = kern_getfsstat(td, &buf, SIZE_T_MAX, &count,
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UIO_SYSSPACE, MNT_WAIT);
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if (error != 0)
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goto out;
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for (sp = buf; count > 0; sp++, count--) {
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error = _mtab_helper(pn, sp, &mntfrom, &mntto, &fstype);
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if (error != 0) {
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MPASS(error == ECANCELED);
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continue;
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}
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if (strncmp(mntto, lep, lep_len) == 0 && mntto[lep_len] == '/')
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mntto += lep_len;
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#if 0
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/*
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* If the prefix is a chroot, and this mountpoint is not under
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* the prefix, we should skip it. Leave it for now for
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* consistency with procmtab above.
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*/
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else
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continue;
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#endif
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/*
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* (1) mount id
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*
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* (2) parent mount id -- we don't have this cheaply, so
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* provide a dummy value
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*
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* (3) major:minor -- ditto
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*
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* (4) root filesystem mount -- probably a namespaces thing
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*
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* (5) mountto path
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*/
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sbuf_printf(sb, "%u 0 0:0 / %s ",
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sp->f_fsid.val[0] ^ sp->f_fsid.val[1], mntto);
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/* (6) mount options */
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_sbuf_mntoptions_helper(sb, sp->f_flags);
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/*
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* (7) zero or more optional fields -- again, namespace related
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*
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* (8) End of variable length fields separator ("-")
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*
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* (9) fstype
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*
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* (10) mount from
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*
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* (11) "superblock" options -- like (6), but different
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* semantics in Linux
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*/
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sbuf_printf(sb, " - %s %s %s\n", fstype, mntfrom,
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(sp->f_flags & MNT_RDONLY) ? "ro" : "rw");
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}
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error = 0;
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out:
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free(buf, M_TEMP);
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free(flep, M_TEMP);
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return (error);
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}
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/*
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* Filler function for proc/partitions
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*/
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@ -1889,6 +2007,8 @@ linprocfs_init(PFS_INIT_ARGS)
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NULL, NULL, NULL, PFS_RD | PFS_AUTODRAIN);
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pfs_create_file(dir, "mem", &linprocfs_doprocmem,
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procfs_attr_rw, &procfs_candebug, NULL, PFS_RDWR | PFS_RAW);
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pfs_create_file(dir, "mountinfo", &linprocfs_doprocmountinfo,
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NULL, NULL, NULL, PFS_RD);
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pfs_create_file(dir, "mounts", &linprocfs_domtab,
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NULL, NULL, NULL, PFS_RD);
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pfs_create_link(dir, "root", &linprocfs_doprocroot,
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