Date: Thu, 10 Aug 2017 05:38:31 +0000 (UTC) From: Dmitry Chagin <dchagin@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-11@freebsd.org Subject: svn commit: r322340 - in stable/11: share/man/man4 share/man/man5 sys/fs/fdescfs sys/kern sys/sys Message-ID: <201708100538.v7A5cVsi013346@repo.freebsd.org>
next in thread | raw e-mail | index | archive | help
Author: dchagin Date: Thu Aug 10 05:38:31 2017 New Revision: 322340 URL: https://svnweb.freebsd.org/changeset/base/322340 Log: MFC r321839: Implement proper Linux /dev/fd and /proc/self/fd behavior by adding Linux specific things to the native fdescfs file system. Unlike FreeBSD, the Linux fdescfs is a directory containing a symbolic links to the actual files, which the process has open. A readlink(2) call on this file returns a full path in case of regular file or a string in a special format (type:[inode], anon_inode:<file-type>, etc..). As well as in a FreeBSD, opening the file in the Linux fdescfs directory is equivalent to duplicating the corresponding file descriptor. Here we have mutually exclusive requirements: - in case of readlink(2) call fdescfs lookup() method should return VLNK vnode otherwise our kern_readlink() fail with EINVAL error; - in the other calls fdescfs lookup() method should return non VLNK vnode. For what new vnode v_flag VV_READLINK was added, which is set if fdescfs has beed mounted with linrdlnk option an modified kern_readlinkat() to properly handle it. For now For Linux ABI compatibility mount fdescfs volume with linrdlnk option: mount -t fdescfs -o linrdlnk null /compat/linux/dev/fd Relnotes: yes Differential Revision: https://reviews.freebsd.org/D11452 Modified: stable/11/share/man/man4/linux.4 stable/11/share/man/man5/fdescfs.5 stable/11/sys/fs/fdescfs/fdesc.h stable/11/sys/fs/fdescfs/fdesc_vfsops.c stable/11/sys/fs/fdescfs/fdesc_vnops.c stable/11/sys/kern/vfs_syscalls.c stable/11/sys/sys/vnode.h Directory Properties: stable/11/ (props changed) Modified: stable/11/share/man/man4/linux.4 ============================================================================== --- stable/11/share/man/man4/linux.4 Thu Aug 10 05:35:45 2017 (r322339) +++ stable/11/share/man/man4/linux.4 Thu Aug 10 05:38:31 2017 (r322340) @@ -24,7 +24,7 @@ .\" .\" $FreeBSD$ .\" -.Dd February 8, 2010 +.Dd August 1, 2017 .Dt LINUX 4 .Os .Sh NAME @@ -127,9 +127,11 @@ regardless of whether the module is statically linked into the kernel or loaded as a module. .Sh FILES -.Bl -tag -width /compat/linux/proc -compact +.Bl -tag -width /compat/linux/dev/fd -compact .It Pa /compat/linux minimal Linux run-time environment +.It Pa /compat/linux/dev/fd +limited Linux file-descriptor file system .It Pa /compat/linux/proc limited Linux process file system .It Pa /compat/linux/sys @@ -138,6 +140,7 @@ limited Linux system file system .Sh SEE ALSO .Xr brandelf 1 , .Xr elf 5 , +.Xr fdescfs 5 , .Xr linprocfs 5 , .Xr linsysfs 5 .Sh HISTORY Modified: stable/11/share/man/man5/fdescfs.5 ============================================================================== --- stable/11/share/man/man5/fdescfs.5 Thu Aug 10 05:35:45 2017 (r322339) +++ stable/11/share/man/man5/fdescfs.5 Thu Aug 10 05:38:31 2017 (r322340) @@ -34,7 +34,7 @@ .\" .\" $FreeBSD$ .\" -.Dd September 18, 2010 +.Dd August 1, 2017 .Dt FDESCFS 5 .Os .Sh NAME @@ -92,6 +92,14 @@ and files are created by default when devfs alone is mounted. .Nm creates entries for all file descriptors opened by the process. +.Pp +For +.Xr linux 4 +ABI compatibility mount +.Nm +volume with +.Cm linrdlnk +option. .Sh FILES .Bl -tag -width /dev/stderr -compact .It Pa /dev/fd/# @@ -103,6 +111,12 @@ volume located on .Pa /dev/fd : .Pp .Dl "mount -t fdescfs null /dev/fd" +.Pp +For +.Xr linux 4 +ABI compatibility: +.Pp +.Dl "mount -t fdescfs -o linrdlnk null /compat/linux/dev/fd" .Sh SEE ALSO .Xr devfs 5 , .Xr mount 8 Modified: stable/11/sys/fs/fdescfs/fdesc.h ============================================================================== --- stable/11/sys/fs/fdescfs/fdesc.h Thu Aug 10 05:35:45 2017 (r322339) +++ stable/11/sys/fs/fdescfs/fdesc.h Thu Aug 10 05:38:31 2017 (r322340) @@ -38,7 +38,9 @@ #define _FS_FDESC_H_ /* Private mount flags for fdescfs. */ -#define FMNT_UNMOUNTF 0x01 +#define FMNT_UNMOUNTF 0x01 +#define FMNT_LINRDLNKF 0x02 + struct fdescmount { struct vnode *f_root; /* Root node */ int flags; Modified: stable/11/sys/fs/fdescfs/fdesc_vfsops.c ============================================================================== --- stable/11/sys/fs/fdescfs/fdesc_vfsops.c Thu Aug 10 05:35:45 2017 (r322339) +++ stable/11/sys/fs/fdescfs/fdesc_vfsops.c Thu Aug 10 05:38:31 2017 (r322340) @@ -101,6 +101,8 @@ fdesc_mount(struct mount *mp) */ mp->mnt_data = fmp; fmp->flags = 0; + if (vfs_getopt(mp->mnt_optnew, "linrdlnk", NULL, NULL) == 0) + fmp->flags |= FMNT_LINRDLNKF; error = fdesc_allocvp(Froot, -1, FD_ROOT, mp, &rvp); if (error) { free(fmp, M_FDESCMNT); Modified: stable/11/sys/fs/fdescfs/fdesc_vnops.c ============================================================================== --- stable/11/sys/fs/fdescfs/fdesc_vnops.c Thu Aug 10 05:35:45 2017 (r322339) +++ stable/11/sys/fs/fdescfs/fdesc_vnops.c Thu Aug 10 05:38:31 2017 (r322340) @@ -69,6 +69,7 @@ static vop_getattr_t fdesc_getattr; static vop_lookup_t fdesc_lookup; static vop_open_t fdesc_open; static vop_readdir_t fdesc_readdir; +static vop_readlink_t fdesc_readlink; static vop_reclaim_t fdesc_reclaim; static vop_setattr_t fdesc_setattr; @@ -81,6 +82,7 @@ static struct vop_vector fdesc_vnodeops = { .vop_open = fdesc_open, .vop_pathconf = vop_stdpathconf, .vop_readdir = fdesc_readdir, + .vop_readlink = fdesc_readlink, .vop_reclaim = fdesc_reclaim, .vop_setattr = fdesc_setattr, }; @@ -195,6 +197,8 @@ loop: fd->fd_type = ftype; fd->fd_fd = fd_fd; fd->fd_ix = ix; + if (ftype == Fdesc && fmp->flags & FMNT_LINRDLNKF) + vp->v_vflag |= VV_READLINK; error = insmntque1(vp, mp, fdesc_insmntque_dtr, NULL); if (error != 0) { *vpp = NULLVP; @@ -420,7 +424,7 @@ fdesc_getattr(struct vop_getattr_args *ap) break; case Fdesc: - vap->va_type = VCHR; + vap->va_type = (vp->v_vflag & VV_READLINK) == 0 ? VCHR : VLNK; vap->va_nlink = 1; vap->va_size = 0; vap->va_rdev = makedev(0, vap->va_fileid); @@ -490,6 +494,7 @@ fdesc_setattr(struct vop_setattr_args *ap) static int fdesc_readdir(struct vop_readdir_args *ap) { + struct fdescmount *fmp; struct uio *uio = ap->a_uio; struct filedesc *fdp; struct dirent d; @@ -499,6 +504,7 @@ fdesc_readdir(struct vop_readdir_args *ap) if (VTOFDESC(ap->a_vp)->fd_type != Froot) panic("fdesc_readdir: not dir"); + fmp = VFSTOFDESC(ap->a_vp->v_mount); if (ap->a_ncookies != NULL) *ap->a_ncookies = 0; @@ -530,7 +536,8 @@ fdesc_readdir(struct vop_readdir_args *ap) break; dp->d_namlen = sprintf(dp->d_name, "%d", fcnt); dp->d_reclen = UIO_MX; - dp->d_type = DT_CHR; + dp->d_type = (fmp->flags & FMNT_LINRDLNKF) == 0 ? + DT_CHR : DT_LNK; dp->d_fileno = i + FD_DESC; break; } @@ -566,4 +573,53 @@ fdesc_reclaim(struct vop_reclaim_args *ap) free(vp->v_data, M_TEMP); vp->v_data = NULL; return (0); +} + +static int +fdesc_readlink(struct vop_readlink_args *va) +{ + struct vnode *vp, *vn; + cap_rights_t rights; + struct thread *td; + struct uio *uio; + struct file *fp; + char *freepath, *fullpath; + size_t pathlen; + int lockflags, fd_fd; + int error; + + freepath = NULL; + vn = va->a_vp; + if (VTOFDESC(vn)->fd_type != Fdesc) + panic("fdesc_readlink: not fdescfs link"); + fd_fd = ((struct fdescnode *)vn->v_data)->fd_fd; + lockflags = VOP_ISLOCKED(vn); + VOP_UNLOCK(vn, 0); + + td = curthread; + error = fget_cap(td, fd_fd, cap_rights_init(&rights), &fp, NULL); + if (error != 0) + goto out; + + switch (fp->f_type) { + case DTYPE_VNODE: + vp = fp->f_vnode; + error = vn_fullpath(td, vp, &fullpath, &freepath); + break; + default: + fullpath = "anon_inode:[unknown]"; + break; + } + if (error == 0) { + uio = va->a_uio; + pathlen = strlen(fullpath); + error = uiomove(fullpath, pathlen, uio); + } + if (freepath != NULL) + free(freepath, M_TEMP); + fdrop(fp, td); + +out: + vn_lock(vn, lockflags | LK_RETRY); + return (error); } Modified: stable/11/sys/kern/vfs_syscalls.c ============================================================================== --- stable/11/sys/kern/vfs_syscalls.c Thu Aug 10 05:35:45 2017 (r322339) +++ stable/11/sys/kern/vfs_syscalls.c Thu Aug 10 05:38:31 2017 (r322340) @@ -2409,7 +2409,7 @@ kern_readlinkat(struct thread *td, int fd, char *path, return (error); } #endif - if (vp->v_type != VLNK) + if (vp->v_type != VLNK && (vp->v_vflag & VV_READLINK) == 0) error = EINVAL; else { aiov.iov_base = buf; Modified: stable/11/sys/sys/vnode.h ============================================================================== --- stable/11/sys/sys/vnode.h Thu Aug 10 05:35:45 2017 (r322339) +++ stable/11/sys/sys/vnode.h Thu Aug 10 05:38:31 2017 (r322340) @@ -253,6 +253,7 @@ struct xvnode { #define VV_DELETED 0x0400 /* should be removed */ #define VV_MD 0x0800 /* vnode backs the md device */ #define VV_FORCEINSMQ 0x1000 /* force the insmntque to succeed */ +#define VV_READLINK 0x2000 /* fdescfs linux vnode */ /* * Vnode attributes. A field value of VNOVAL represents a field whose value
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201708100538.v7A5cVsi013346>