Date: Tue, 19 Dec 2017 18:20:38 +0000 (UTC) From: John Baldwin <jhb@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r326986 - in head/sys: fs/fdescfs kern sys Message-ID: <201712191820.vBJIKcPB045388@repo.freebsd.org>
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Author: jhb Date: Tue Dec 19 18:20:38 2017 New Revision: 326986 URL: https://svnweb.freebsd.org/changeset/base/326986 Log: Add a custom VOP_PATHCONF method for fdescfs. The method handles NAME_MAX and LINK_MAX explicitly. For all other pathconf variables, the method passes the request down to the underlying file descriptor. This requires splitting a kern_fpathconf() syscallsubr routine out of sys_fpathconf(). Also, to avoid lock order reversals with vnode locks, the fdescfs vnode is unlocked around the call to kern_fpathconf(), but with the usecount of the vnode bumped. MFC after: 1 month Sponsored by: Chelsio Communications Modified: head/sys/fs/fdescfs/fdesc_vnops.c head/sys/kern/kern_descrip.c head/sys/sys/syscallsubr.h Modified: head/sys/fs/fdescfs/fdesc_vnops.c ============================================================================== --- head/sys/fs/fdescfs/fdesc_vnops.c Tue Dec 19 18:12:18 2017 (r326985) +++ head/sys/fs/fdescfs/fdesc_vnops.c Tue Dec 19 18:20:38 2017 (r326986) @@ -55,6 +55,8 @@ #include <sys/namei.h> #include <sys/proc.h> #include <sys/stat.h> +#include <sys/syscallsubr.h> +#include <sys/unistd.h> #include <sys/vnode.h> #include <fs/fdescfs/fdesc.h> @@ -70,6 +72,7 @@ struct mtx fdesc_hashmtx; static vop_getattr_t fdesc_getattr; static vop_lookup_t fdesc_lookup; static vop_open_t fdesc_open; +static vop_pathconf_t fdesc_pathconf; static vop_readdir_t fdesc_readdir; static vop_readlink_t fdesc_readlink; static vop_reclaim_t fdesc_reclaim; @@ -82,7 +85,7 @@ static struct vop_vector fdesc_vnodeops = { .vop_getattr = fdesc_getattr, .vop_lookup = fdesc_lookup, .vop_open = fdesc_open, - .vop_pathconf = vop_stdpathconf, + .vop_pathconf = fdesc_pathconf, .vop_readdir = fdesc_readdir, .vop_readlink = fdesc_readlink, .vop_reclaim = fdesc_reclaim, @@ -393,6 +396,33 @@ fdesc_open(struct vop_open_args *ap) */ ap->a_td->td_dupfd = VTOFDESC(vp)->fd_fd; /* XXX */ return (ENODEV); +} + +static int +fdesc_pathconf(struct vop_pathconf_args *ap) +{ + struct vnode *vp = ap->a_vp; + int error; + + switch (ap->a_name) { + case _PC_NAME_MAX: + *ap->a_retval = NAME_MAX; + return (0); + case _PC_LINK_MAX: + if (VTOFDESC(vp)->fd_type == Froot) + *ap->a_retval = 2; + else + *ap->a_retval = 1; + return (0); + default: + vref(vp); + VOP_UNLOCK(vp, 0); + error = kern_fpathconf(curthread, VTOFDESC(vp)->fd_fd, + ap->a_name); + vn_lock(vp, LK_SHARED | LK_RETRY); + vunref(vp); + return (error); + } } static int Modified: head/sys/kern/kern_descrip.c ============================================================================== --- head/sys/kern/kern_descrip.c Tue Dec 19 18:12:18 2017 (r326985) +++ head/sys/kern/kern_descrip.c Tue Dec 19 18:20:38 2017 (r326986) @@ -1418,26 +1418,33 @@ struct fpathconf_args { int sys_fpathconf(struct thread *td, struct fpathconf_args *uap) { + + return (kern_fpathconf(td, uap->fd, uap->name)); +} + +int +kern_fpathconf(struct thread *td, int fd, int name) +{ struct file *fp; struct vnode *vp; cap_rights_t rights; int error; - error = fget(td, uap->fd, cap_rights_init(&rights, CAP_FPATHCONF), &fp); + error = fget(td, fd, cap_rights_init(&rights, CAP_FPATHCONF), &fp); if (error != 0) return (error); - if (uap->name == _PC_ASYNC_IO) { + if (name == _PC_ASYNC_IO) { td->td_retval[0] = _POSIX_ASYNCHRONOUS_IO; goto out; } vp = fp->f_vnode; if (vp != NULL) { vn_lock(vp, LK_SHARED | LK_RETRY); - error = VOP_PATHCONF(vp, uap->name, td->td_retval); + error = VOP_PATHCONF(vp, name, td->td_retval); VOP_UNLOCK(vp, 0); } else if (fp->f_type == DTYPE_PIPE || fp->f_type == DTYPE_SOCKET) { - if (uap->name != _PC_PIPE_BUF) { + if (name != _PC_PIPE_BUF) { error = EINVAL; } else { td->td_retval[0] = PIPE_BUF; Modified: head/sys/sys/syscallsubr.h ============================================================================== --- head/sys/sys/syscallsubr.h Tue Dec 19 18:12:18 2017 (r326985) +++ head/sys/sys/syscallsubr.h Tue Dec 19 18:20:38 2017 (r326986) @@ -111,6 +111,7 @@ int kern_fcntl(struct thread *td, int fd, int cmd, int int kern_fcntl_freebsd(struct thread *td, int fd, int cmd, long arg); int kern_fhstat(struct thread *td, fhandle_t fh, struct stat *buf); int kern_fhstatfs(struct thread *td, fhandle_t fh, struct statfs *buf); +int kern_fpathconf(struct thread *td, int fd, int name); int kern_fstat(struct thread *td, int fd, struct stat *sbp); int kern_fstatfs(struct thread *td, int fd, struct statfs *buf); int kern_fsync(struct thread *td, int fd, bool fullsync);
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