/*- * SPDX-License-Identifier: BSD-3-Clause * * Copyright (c) 1992, 1993, 1995 * The Regents of the University of California. All rights reserved. * * This code is derived from software donated to Berkeley by * Jan-Simon Pendry. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ /* * /dev/fd Filesystem */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include static MALLOC_DEFINE(M_FDESCMNT, "fdesc_mount", "FDESC mount structure"); static vfs_cmount_t fdesc_cmount; static vfs_mount_t fdesc_mount; static vfs_unmount_t fdesc_unmount; static vfs_statfs_t fdesc_statfs; static vfs_root_t fdesc_root; /* * Compatibility shim for old mount(2) system call. */ int fdesc_cmount(struct mntarg *ma, void *data, uint64_t flags) { return kernel_mount(ma, flags); } /* * Mount the per-process file descriptors (/dev/fd) */ static int fdesc_mount(struct mount *mp) { struct fdescmount *fmp; struct vnode *rvp; int error; /* * Update is a no-op */ if (mp->mnt_flag & (MNT_UPDATE | MNT_ROOTFS)) return (EOPNOTSUPP); fmp = malloc(sizeof(struct fdescmount), M_FDESCMNT, M_WAITOK); /* * We need to initialize a few bits of our local mount point struct to * avoid confusion in allocvp. */ mp->mnt_data = fmp; fmp->flags = 0; if (vfs_getopt(mp->mnt_optnew, "linrdlnk", NULL, NULL) == 0) fmp->flags |= FMNT_LINRDLNKF; if (vfs_getopt(mp->mnt_optnew, "rdlnk", NULL, NULL) == 0) fmp->flags |= FMNT_RDLNKF; if (vfs_getopt(mp->mnt_optnew, "nodup", NULL, NULL) == 0) fmp->flags |= FMNT_NODUP; error = fdesc_allocvp(Froot, -1, FD_ROOT, mp, &rvp); if (error) { free(fmp, M_FDESCMNT); mp->mnt_data = NULL; return (error); } VN_LOCK_ASHARE(rvp); rvp->v_type = VDIR; rvp->v_vflag |= VV_ROOT; fmp->f_root = rvp; VOP_UNLOCK(rvp); MNT_ILOCK(mp); /* XXX -- don't mark as local to work around fts() problems */ /*mp->mnt_flag |= MNT_LOCAL;*/ /* * Enable shared locking so that there is no contention on the root * vnode. Note only root vnode enables shared locking for itself, * so this end up being a nop for the rest. */ mp->mnt_kern_flag |= MNTK_LOOKUP_SHARED | MNTK_EXTENDED_SHARED; MNT_IUNLOCK(mp); vfs_getnewfsid(mp); vfs_mountedfrom(mp, "fdescfs"); return (0); } static int fdesc_unmount(struct mount *mp, int mntflags) { struct fdescmount *fmp; int error, flags; flags = 0; fmp = mp->mnt_data; if (mntflags & MNT_FORCE) { /* The hash mutex protects the private mount flags. */ mtx_lock(&fdesc_hashmtx); fmp->flags |= FMNT_UNMOUNTF; mtx_unlock(&fdesc_hashmtx); flags |= FORCECLOSE; } /* * Clear out buffer cache. I don't think we * ever get anything cached at this level at the * moment, but who knows... * * There is 1 extra root vnode reference corresponding * to f_root. */ if ((error = vflush(mp, 1, flags, curthread)) != 0) return (error); /* * Finally, throw away the fdescmount structure. */ mp->mnt_data = NULL; free(fmp, M_FDESCMNT); return (0); } static int fdesc_root(struct mount *mp, int flags, struct vnode **vpp) { struct vnode *vp; /* * Return locked reference to root. */ vp = VFSTOFDESC(mp)->f_root; vget(vp, flags | LK_RETRY); *vpp = vp; return (0); } static int fdesc_statfs(struct mount *mp, struct statfs *sbp) { struct thread *td; struct filedesc *fdp; int lim; int i; int last; int freefd; uint64_t limit; td = curthread; /* * Compute number of free file descriptors. * [ Strange results will ensue if the open file * limit is ever reduced below the current number * of open files... ] */ lim = lim_cur(td, RLIMIT_NOFILE); fdp = td->td_proc->p_fd; FILEDESC_SLOCK(fdp); limit = racct_get_limit(td->td_proc, RACCT_NOFILE); if (lim > limit) lim = limit; last = min(fdp->fd_nfiles, lim); freefd = 0; for (i = fdp->fd_freefile; i < last; i++) if (fdp->fd_ofiles[i].fde_file == NULL) freefd++; /* * Adjust for the fact that the fdesc array may not * have been fully allocated yet. */ if (fdp->fd_nfiles < lim) freefd += (lim - fdp->fd_nfiles); FILEDESC_SUNLOCK(fdp); sbp->f_flags = mp->mnt_flag & MNT_IGNORE; sbp->f_bsize = DEV_BSIZE; sbp->f_iosize = DEV_BSIZE; sbp->f_blocks = 2; /* 1K to keep df happy */ sbp->f_bfree = 2; sbp->f_bavail = 2; sbp->f_files = lim + 1; /* Allow for "." */ sbp->f_ffree = freefd; /* See comments above */ return (0); } static struct vfsops fdesc_vfsops = { .vfs_cmount = fdesc_cmount, .vfs_init = fdesc_init, .vfs_mount = fdesc_mount, .vfs_root = fdesc_root, .vfs_statfs = fdesc_statfs, .vfs_uninit = fdesc_uninit, .vfs_unmount = fdesc_unmount, }; VFS_SET(fdesc_vfsops, fdescfs, VFCF_SYNTHETIC | VFCF_JAIL);