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      1 /*
      2  * CDDL HEADER START
      3  *
      4  * The contents of this file are subject to the terms of the
      5  * Common Development and Distribution License (the "License").
      6  * You may not use this file except in compliance with the License.
      7  *
      8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
      9  * or http://www.opensolaris.org/os/licensing.
     10  * See the License for the specific language governing permissions
     11  * and limitations under the License.
     12  *
     13  * When distributing Covered Code, include this CDDL HEADER in each
     14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
     15  * If applicable, add the following below this CDDL HEADER, with the
     16  * fields enclosed by brackets "[]" replaced with your own identifying
     17  * information: Portions Copyright [yyyy] [name of copyright owner]
     18  *
     19  * CDDL HEADER END
     20  */
     21 
     22 /*
     23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
     24  * Use is subject to license terms.
     25  */
     26 
     27 /*	Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T	*/
     28 /*	  All Rights Reserved  	*/
     29 
     30 /*
     31  * Portions of this source code were derived from Berkeley 4.3 BSD
     32  * under license from the Regents of the University of California.
     33  */
     34 
     35 #pragma ident	"%Z%%M%	%I%	%E% SMI"
     36 
     37 #include <sys/param.h>
     38 #include <sys/isa_defs.h>
     39 #include <sys/types.h>
     40 #include <sys/sysmacros.h>
     41 #include <sys/cred.h>
     42 #include <sys/systm.h>
     43 #include <sys/errno.h>
     44 #include <sys/pathname.h>
     45 #include <sys/vnode.h>
     46 #include <sys/vfs.h>
     47 #include <sys/file.h>
     48 #include <sys/uio.h>
     49 #include <sys/debug.h>
     50 #include <fs/fs_subr.h>
     51 
     52 /*
     53  * Common code for pathconf(), fpathconf() system calls
     54  */
     55 static long
     56 cpathconf(register vnode_t *vp, int cmd, struct cred *cr)
     57 {
     58 	struct statvfs64 sb;
     59 	int error;
     60 	ulong_t val;
     61 
     62 	switch (cmd) {
     63 	case _PC_2_SYMLINKS:
     64 		if (error = VOP_PATHCONF(vp, _PC_SYMLINK_MAX, &val, cr, NULL))
     65 			return ((long)set_errno(error));
     66 		return ((long)(val > 0));
     67 
     68 	case _PC_ALLOC_SIZE_MIN:
     69 	case _PC_REC_INCR_XFER_SIZE:
     70 	case _PC_REC_MAX_XFER_SIZE:
     71 	case _PC_REC_MIN_XFER_SIZE:
     72 	case _PC_REC_XFER_ALIGN:
     73 		if ((error = VFS_STATVFS(vp->v_vfsp, &sb)) != 0)
     74 			return ((long)set_errno(error));
     75 
     76 		/*
     77 		 * There is generally no harm in doing larger transfers, but
     78 		 * there's a point of diminishing returns.  With 1MB transfers,
     79 		 * even if they're random, you get very close to platter speed.
     80 		 * Se we return 1MB as the maximum transfer size.
     81 		 */
     82 		if (cmd == _PC_REC_MAX_XFER_SIZE)
     83 			return ((long)MAX(sb.f_bsize, 1UL << 20));
     84 
     85 		/*
     86 		 * By definition, f_frsize is the smallest filesystem block.
     87 		 * However, _PC_ALLOC_SIZE_MIN is intended to define the
     88 		 * threshold for direct I/O.  This implies two requirements:
     89 		 * the VM and I/O subsystems must be able to create mappings
     90 		 * for DMA, which requires at least page alignment; and the
     91 		 * filesystem must avoid read/modify/write, which generally
     92 		 * requires multiples of its 'preferred' blocksize, f_bsize.
     93 		 *
     94 		 * PAGESIZE alignment is sufficient for DMA and block copy.
     95 		 * Rounding up to the filesystem 'preferred' blocksize
     96 		 * works just as well.
     97 		 *
     98 		 * All together, this means that the remaining parameters
     99 		 * map into the same value.
    100 		 */
    101 		return ((long)MAX(sb.f_bsize, PAGESIZE));
    102 
    103 	case _PC_ASYNC_IO:
    104 		return (1l);
    105 
    106 	case _PC_PRIO_IO:
    107 		return ((long)set_errno(EINVAL));
    108 
    109 	case _PC_SYNC_IO:
    110 		if (!(error = VOP_FSYNC(vp, FSYNC, cr, NULL)))
    111 			return (1l);
    112 		return ((long)set_errno(error));
    113 
    114 	case _PC_XATTR_ENABLED:
    115 		return ((vp->v_vfsp->vfs_flag & VFS_XATTR) ? 1 : 0);
    116 
    117 	default:
    118 		if (error = VOP_PATHCONF(vp, cmd, &val, cr, NULL))
    119 			return ((long)set_errno(error));
    120 		return (val);
    121 	}
    122 	/* NOTREACHED */
    123 }
    124 
    125 /* fpathconf/pathconf interfaces */
    126 
    127 long
    128 fpathconf(int fdes, int name)
    129 {
    130 	file_t *fp;
    131 	long retval;
    132 
    133 	if ((fp = getf(fdes)) == NULL)
    134 		return (set_errno(EBADF));
    135 	retval = cpathconf(fp->f_vnode, name, fp->f_cred);
    136 	releasef(fdes);
    137 	return (retval);
    138 }
    139 
    140 long
    141 pathconf(char *fname, int name)
    142 {
    143 	vnode_t *vp;
    144 	long	retval;
    145 	int	error;
    146 	int 	estale_retry = 0;
    147 
    148 lookup:
    149 	if (error = lookupname(fname, UIO_USERSPACE, FOLLOW, NULLVPP, &vp)) {
    150 		if ((error == ESTALE) && fs_need_estale_retry(estale_retry++))
    151 			goto lookup;
    152 		return ((long)set_errno(error));
    153 	}
    154 
    155 	retval = cpathconf(vp, name, CRED());
    156 	VN_RELE(vp);
    157 	return (retval);
    158 }
    159