296a25a245
- Don't deduct wired pages from total usable counts because it does not make any sense. To make things worse, on systems where swap size is smaller than physical memory and use a lot of wired pages (e.g. ZFS), tmpfs can suddenly have free space of 0 because of this; - Count cached pages as available; [1] - Don't count inactive pages as available, technically we could but that might be too aggressive; [1] [1] Suggested by kib@ MFC after: 1 week
584 lines
21 KiB
C
584 lines
21 KiB
C
/* $NetBSD: tmpfs.h,v 1.26 2007/02/22 06:37:00 thorpej Exp $ */
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/*-
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* Copyright (c) 2005, 2006 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Julio M. Merino Vidal, developed as part of Google's Summer of Code
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* 2005 program.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#ifndef _FS_TMPFS_TMPFS_H_
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#define _FS_TMPFS_TMPFS_H_
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/* ---------------------------------------------------------------------
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* KERNEL-SPECIFIC DEFINITIONS
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* --------------------------------------------------------------------- */
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#include <sys/dirent.h>
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#include <sys/mount.h>
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#include <sys/queue.h>
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#include <sys/vnode.h>
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#include <sys/file.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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/* --------------------------------------------------------------------- */
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#include <sys/malloc.h>
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#include <sys/systm.h>
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#include <sys/vmmeter.h>
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#include <vm/swap_pager.h>
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MALLOC_DECLARE(M_TMPFSMNT);
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MALLOC_DECLARE(M_TMPFSNAME);
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/* --------------------------------------------------------------------- */
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/*
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* Internal representation of a tmpfs directory entry.
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*/
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struct tmpfs_dirent {
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TAILQ_ENTRY(tmpfs_dirent) td_entries;
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/* Length of the name stored in this directory entry. This avoids
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* the need to recalculate it every time the name is used. */
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uint16_t td_namelen;
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/* The name of the entry, allocated from a string pool. This
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* string is not required to be zero-terminated; therefore, the
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* td_namelen field must always be used when accessing its value. */
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char * td_name;
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/* Pointer to the node this entry refers to. In case this field
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* is NULL, the node is a whiteout. */
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struct tmpfs_node * td_node;
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};
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/* A directory in tmpfs holds a sorted list of directory entries, which in
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* turn point to other files (which can be directories themselves).
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*
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* In tmpfs, this list is managed by a tail queue, whose head is defined by
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* the struct tmpfs_dir type.
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*
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* It is imporant to notice that directories do not have entries for . and
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* .. as other file systems do. These can be generated when requested
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* based on information available by other means, such as the pointer to
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* the node itself in the former case or the pointer to the parent directory
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* in the latter case. This is done to simplify tmpfs's code and, more
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* importantly, to remove redundancy. */
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TAILQ_HEAD(tmpfs_dir, tmpfs_dirent);
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/* Each entry in a directory has a cookie that identifies it. Cookies
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* supersede offsets within directories because, given how tmpfs stores
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* directories in memory, there is no such thing as an offset. (Emulating
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* a real offset could be very difficult.)
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*
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* The '.', '..' and the end of directory markers have fixed cookies which
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* cannot collide with the cookies generated by other entries. The cookies
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* fot the other entries are generated based on the memory address on which
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* stores their information is stored.
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*
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* Ideally, using the entry's memory pointer as the cookie would be enough
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* to represent it and it wouldn't cause collisions in any system.
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* Unfortunately, this results in "offsets" with very large values which
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* later raise problems in the Linux compatibility layer (and maybe in other
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* places) as described in PR kern/32034. Hence we need to workaround this
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* with a rather ugly hack.
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*
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* Linux 32-bit binaries, unless built with _FILE_OFFSET_BITS=64, have off_t
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* set to 'long', which is a 32-bit *signed* long integer. Regardless of
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* the macro value, GLIBC (2.3 at least) always uses the getdents64
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* system call (when calling readdir) which internally returns off64_t
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* offsets. In order to make 32-bit binaries work, *GLIBC* converts the
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* 64-bit values returned by the kernel to 32-bit ones and aborts with
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* EOVERFLOW if the conversion results in values that won't fit in 32-bit
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* integers (which it assumes is because the directory is extremely large).
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* This wouldn't cause problems if we were dealing with unsigned integers,
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* but as we have signed integers, this check fails due to sign expansion.
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*
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* For example, consider that the kernel returns the 0xc1234567 cookie to
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* userspace in a off64_t integer. Later on, GLIBC casts this value to
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* off_t (remember, signed) with code similar to:
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* system call returns the offset in kernel_value;
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* off_t casted_value = kernel_value;
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* if (sizeof(off_t) != sizeof(off64_t) &&
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* kernel_value != casted_value)
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* error!
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* In this case, casted_value still has 0xc1234567, but when it is compared
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* for equality against kernel_value, it is promoted to a 64-bit integer and
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* becomes 0xffffffffc1234567, which is different than 0x00000000c1234567.
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* Then, GLIBC assumes this is because the directory is very large.
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*
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* Given that all the above happens in user-space, we have no control over
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* it; therefore we must workaround the issue here. We do this by
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* truncating the pointer value to a 32-bit integer and hope that there
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* won't be collisions. In fact, this will not cause any problems in
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* 32-bit platforms but some might arise in 64-bit machines (I'm not sure
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* if they can happen at all in practice).
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*
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* XXX A nicer solution shall be attempted. */
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#ifdef _KERNEL
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#define TMPFS_DIRCOOKIE_DOT 0
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#define TMPFS_DIRCOOKIE_DOTDOT 1
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#define TMPFS_DIRCOOKIE_EOF 2
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static __inline
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off_t
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tmpfs_dircookie(struct tmpfs_dirent *de)
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{
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off_t cookie;
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cookie = ((off_t)(uintptr_t)de >> 1) & 0x7FFFFFFF;
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MPASS(cookie != TMPFS_DIRCOOKIE_DOT);
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MPASS(cookie != TMPFS_DIRCOOKIE_DOTDOT);
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MPASS(cookie != TMPFS_DIRCOOKIE_EOF);
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return cookie;
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}
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#endif
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/* --------------------------------------------------------------------- */
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/*
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* Internal representation of a tmpfs file system node.
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*
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* This structure is splitted in two parts: one holds attributes common
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* to all file types and the other holds data that is only applicable to
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* a particular type. The code must be careful to only access those
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* attributes that are actually allowed by the node's type.
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*
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*
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* Below is the key of locks used to protected the fields in the following
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* structures.
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*
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*/
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struct tmpfs_node {
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/* Doubly-linked list entry which links all existing nodes for a
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* single file system. This is provided to ease the removal of
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* all nodes during the unmount operation. */
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LIST_ENTRY(tmpfs_node) tn_entries;
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/* The node's type. Any of 'VBLK', 'VCHR', 'VDIR', 'VFIFO',
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* 'VLNK', 'VREG' and 'VSOCK' is allowed. The usage of vnode
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* types instead of a custom enumeration is to make things simpler
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* and faster, as we do not need to convert between two types. */
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enum vtype tn_type;
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/* Node identifier. */
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ino_t tn_id;
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/* Node's internal status. This is used by several file system
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* operations to do modifications to the node in a delayed
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* fashion. */
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int tn_status;
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#define TMPFS_NODE_ACCESSED (1 << 1)
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#define TMPFS_NODE_MODIFIED (1 << 2)
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#define TMPFS_NODE_CHANGED (1 << 3)
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/* The node size. It does not necessarily match the real amount
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* of memory consumed by it. */
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off_t tn_size;
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/* Generic node attributes. */
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uid_t tn_uid;
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gid_t tn_gid;
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mode_t tn_mode;
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int tn_flags;
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nlink_t tn_links;
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struct timespec tn_atime;
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struct timespec tn_mtime;
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struct timespec tn_ctime;
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struct timespec tn_birthtime;
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unsigned long tn_gen;
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/* As there is a single vnode for each active file within the
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* system, care has to be taken to avoid allocating more than one
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* vnode per file. In order to do this, a bidirectional association
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* is kept between vnodes and nodes.
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*
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* Whenever a vnode is allocated, its v_data field is updated to
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* point to the node it references. At the same time, the node's
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* tn_vnode field is modified to point to the new vnode representing
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* it. Further attempts to allocate a vnode for this same node will
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* result in returning a new reference to the value stored in
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* tn_vnode.
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*
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* May be NULL when the node is unused (that is, no vnode has been
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* allocated for it or it has been reclaimed). */
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struct vnode * tn_vnode;
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/* interlock to protect tn_vpstate */
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struct mtx tn_interlock;
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/* Identify if current node has vnode assiocate with
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* or allocating vnode.
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*/
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int tn_vpstate;
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/* misc data field for different tn_type node */
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union {
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/* Valid when tn_type == VBLK || tn_type == VCHR. */
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dev_t tn_rdev;
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/* Valid when tn_type == VDIR. */
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struct tn_dir{
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/* Pointer to the parent directory. The root
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* directory has a pointer to itself in this field;
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* this property identifies the root node. */
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struct tmpfs_node * tn_parent;
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/* Head of a tail-queue that links the contents of
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* the directory together. See above for a
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* description of its contents. */
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struct tmpfs_dir tn_dirhead;
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/* Number and pointer of the first directory entry
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* returned by the readdir operation if it were
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* called again to continue reading data from the
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* same directory as before. This is used to speed
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* up reads of long directories, assuming that no
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* more than one read is in progress at a given time.
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* Otherwise, these values are discarded and a linear
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* scan is performed from the beginning up to the
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* point where readdir starts returning values. */
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off_t tn_readdir_lastn;
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struct tmpfs_dirent * tn_readdir_lastp;
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}tn_dir;
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/* Valid when tn_type == VLNK. */
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/* The link's target, allocated from a string pool. */
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char * tn_link;
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/* Valid when tn_type == VREG. */
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struct tn_reg {
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/* The contents of regular files stored in a tmpfs
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* file system are represented by a single anonymous
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* memory object (aobj, for short). The aobj provides
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* direct access to any position within the file,
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* because its contents are always mapped in a
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* contiguous region of virtual memory. It is a task
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* of the memory management subsystem (see uvm(9)) to
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* issue the required page ins or page outs whenever
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* a position within the file is accessed. */
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vm_object_t tn_aobj;
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}tn_reg;
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/* Valid when tn_type = VFIFO */
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struct tn_fifo {
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fo_rdwr_t *tn_fo_read;
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fo_rdwr_t *tn_fo_write;
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}tn_fifo;
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}tn_spec;
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};
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LIST_HEAD(tmpfs_node_list, tmpfs_node);
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#define tn_rdev tn_spec.tn_rdev
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#define tn_dir tn_spec.tn_dir
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#define tn_link tn_spec.tn_link
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#define tn_reg tn_spec.tn_reg
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#define tn_fifo tn_spec.tn_fifo
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#define TMPFS_NODE_LOCK(node) mtx_lock(&(node)->tn_interlock)
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#define TMPFS_NODE_UNLOCK(node) mtx_unlock(&(node)->tn_interlock)
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#define TMPFS_NODE_MTX(node) (&(node)->tn_interlock)
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#ifdef INVARIANTS
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#define TMPFS_ASSERT_LOCKED(node) do { \
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MPASS(node != NULL); \
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MPASS(node->tn_vnode != NULL); \
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if (!VOP_ISLOCKED(node->tn_vnode) && \
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!mtx_owned(TMPFS_NODE_MTX(node))) \
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panic("tmpfs: node is not locked: %p", node); \
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} while (0)
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#define TMPFS_ASSERT_ELOCKED(node) do { \
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MPASS((node) != NULL); \
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MPASS((node)->tn_vnode != NULL); \
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mtx_assert(TMPFS_NODE_MTX(node), MA_OWNED); \
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ASSERT_VOP_LOCKED((node)->tn_vnode, "tmpfs"); \
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} while (0)
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#else
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#define TMPFS_ASSERT_LOCKED(node) (void)0
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#define TMPFS_ASSERT_ELOCKED(node) (void)0
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#endif
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#define TMPFS_VNODE_ALLOCATING 1
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#define TMPFS_VNODE_WANT 2
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#define TMPFS_VNODE_DOOMED 4
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/* --------------------------------------------------------------------- */
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/*
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* Internal representation of a tmpfs mount point.
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*/
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struct tmpfs_mount {
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/* Maximum number of memory pages available for use by the file
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* system, set during mount time. This variable must never be
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* used directly as it may be bigger than the current amount of
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* free memory; in the extreme case, it will hold the SIZE_MAX
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* value. Instead, use the TMPFS_PAGES_MAX macro. */
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size_t tm_pages_max;
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/* Number of pages in use by the file system. Cannot be bigger
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* than the value returned by TMPFS_PAGES_MAX in any case. */
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size_t tm_pages_used;
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/* Pointer to the node representing the root directory of this
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* file system. */
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struct tmpfs_node * tm_root;
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/* Maximum number of possible nodes for this file system; set
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* during mount time. We need a hard limit on the maximum number
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* of nodes to avoid allocating too much of them; their objects
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* cannot be released until the file system is unmounted.
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* Otherwise, we could easily run out of memory by creating lots
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* of empty files and then simply removing them. */
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ino_t tm_nodes_max;
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/* unrhdr used to allocate inode numbers */
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struct unrhdr * tm_ino_unr;
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/* Number of nodes currently that are in use. */
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ino_t tm_nodes_inuse;
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/* maximum representable file size */
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u_int64_t tm_maxfilesize;
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/* Nodes are organized in two different lists. The used list
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* contains all nodes that are currently used by the file system;
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* i.e., they refer to existing files. The available list contains
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* all nodes that are currently available for use by new files.
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* Nodes must be kept in this list (instead of deleting them)
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* because we need to keep track of their generation number (tn_gen
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* field).
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*
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* Note that nodes are lazily allocated: if the available list is
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* empty and we have enough space to create more nodes, they will be
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* created and inserted in the used list. Once these are released,
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* they will go into the available list, remaining alive until the
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* file system is unmounted. */
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struct tmpfs_node_list tm_nodes_used;
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/* All node lock to protect the node list and tmp_pages_used */
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struct mtx allnode_lock;
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/* Pools used to store file system meta data. These are not shared
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* across several instances of tmpfs for the reasons described in
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* tmpfs_pool.c. */
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uma_zone_t tm_dirent_pool;
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uma_zone_t tm_node_pool;
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};
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#define TMPFS_LOCK(tm) mtx_lock(&(tm)->allnode_lock)
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#define TMPFS_UNLOCK(tm) mtx_unlock(&(tm)->allnode_lock)
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/* --------------------------------------------------------------------- */
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/*
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* This structure maps a file identifier to a tmpfs node. Used by the
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* NFS code.
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*/
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struct tmpfs_fid {
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uint16_t tf_len;
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uint16_t tf_pad;
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ino_t tf_id;
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unsigned long tf_gen;
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};
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/* --------------------------------------------------------------------- */
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#ifdef _KERNEL
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/*
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* Prototypes for tmpfs_subr.c.
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*/
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int tmpfs_alloc_node(struct tmpfs_mount *, enum vtype,
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uid_t uid, gid_t gid, mode_t mode, struct tmpfs_node *,
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char *, dev_t, struct tmpfs_node **);
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void tmpfs_free_node(struct tmpfs_mount *, struct tmpfs_node *);
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int tmpfs_alloc_dirent(struct tmpfs_mount *, struct tmpfs_node *,
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const char *, uint16_t, struct tmpfs_dirent **);
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void tmpfs_free_dirent(struct tmpfs_mount *, struct tmpfs_dirent *,
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boolean_t);
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int tmpfs_alloc_vp(struct mount *, struct tmpfs_node *, int,
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struct vnode **);
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void tmpfs_free_vp(struct vnode *);
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int tmpfs_alloc_file(struct vnode *, struct vnode **, struct vattr *,
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struct componentname *, char *);
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void tmpfs_dir_attach(struct vnode *, struct tmpfs_dirent *);
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void tmpfs_dir_detach(struct vnode *, struct tmpfs_dirent *);
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struct tmpfs_dirent * tmpfs_dir_lookup(struct tmpfs_node *node,
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struct tmpfs_node *f,
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struct componentname *cnp);
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int tmpfs_dir_getdotdent(struct tmpfs_node *, struct uio *);
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int tmpfs_dir_getdotdotdent(struct tmpfs_node *, struct uio *);
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struct tmpfs_dirent * tmpfs_dir_lookupbycookie(struct tmpfs_node *, off_t);
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int tmpfs_dir_getdents(struct tmpfs_node *, struct uio *, off_t *);
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int tmpfs_dir_whiteout_add(struct vnode *, struct componentname *);
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void tmpfs_dir_whiteout_remove(struct vnode *, struct componentname *);
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int tmpfs_reg_resize(struct vnode *, off_t);
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int tmpfs_chflags(struct vnode *, int, struct ucred *, struct thread *);
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int tmpfs_chmod(struct vnode *, mode_t, struct ucred *, struct thread *);
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int tmpfs_chown(struct vnode *, uid_t, gid_t, struct ucred *,
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struct thread *);
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int tmpfs_chsize(struct vnode *, u_quad_t, struct ucred *, struct thread *);
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int tmpfs_chtimes(struct vnode *, struct timespec *, struct timespec *,
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struct timespec *, int, struct ucred *, struct thread *);
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void tmpfs_itimes(struct vnode *, const struct timespec *,
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const struct timespec *);
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void tmpfs_update(struct vnode *);
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int tmpfs_truncate(struct vnode *, off_t);
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|
|
|
/* --------------------------------------------------------------------- */
|
|
|
|
/*
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|
* Convenience macros to simplify some logical expressions.
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|
*/
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|
#define IMPLIES(a, b) (!(a) || (b))
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|
#define IFF(a, b) (IMPLIES(a, b) && IMPLIES(b, a))
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|
|
|
/* --------------------------------------------------------------------- */
|
|
|
|
/*
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|
* Checks that the directory entry pointed by 'de' matches the name 'name'
|
|
* with a length of 'len'.
|
|
*/
|
|
#define TMPFS_DIRENT_MATCHES(de, name, len) \
|
|
(de->td_namelen == (uint16_t)len && \
|
|
bcmp((de)->td_name, (name), (de)->td_namelen) == 0)
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|
|
|
/* --------------------------------------------------------------------- */
|
|
|
|
/*
|
|
* Ensures that the node pointed by 'node' is a directory and that its
|
|
* contents are consistent with respect to directories.
|
|
*/
|
|
#define TMPFS_VALIDATE_DIR(node) \
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|
MPASS((node)->tn_type == VDIR); \
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|
MPASS((node)->tn_size % sizeof(struct tmpfs_dirent) == 0); \
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|
MPASS((node)->tn_dir.tn_readdir_lastp == NULL || \
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|
tmpfs_dircookie((node)->tn_dir.tn_readdir_lastp) == (node)->tn_dir.tn_readdir_lastn);
|
|
|
|
/* --------------------------------------------------------------------- */
|
|
|
|
/*
|
|
* Memory management stuff.
|
|
*/
|
|
|
|
/* Amount of memory pages to reserve for the system (e.g., to not use by
|
|
* tmpfs).
|
|
* XXX: Should this be tunable through sysctl, for instance? */
|
|
#define TMPFS_PAGES_RESERVED (4 * 1024 * 1024 / PAGE_SIZE)
|
|
|
|
/*
|
|
* Returns information about the number of available memory pages,
|
|
* including physical and virtual ones.
|
|
*
|
|
* Remember to remove TMPFS_PAGES_RESERVED from the returned value to avoid
|
|
* excessive memory usage.
|
|
*
|
|
*/
|
|
static __inline size_t
|
|
tmpfs_mem_info(void)
|
|
{
|
|
|
|
return (swap_pager_avail + cnt.v_free_count + cnt.v_cache_count);
|
|
}
|
|
|
|
/* Returns the maximum size allowed for a tmpfs file system. This macro
|
|
* must be used instead of directly retrieving the value from tm_pages_max.
|
|
* The reason is that the size of a tmpfs file system is dynamic: it lets
|
|
* the user store files as long as there is enough free memory (including
|
|
* physical memory and swap space). Therefore, the amount of memory to be
|
|
* used is either the limit imposed by the user during mount time or the
|
|
* amount of available memory, whichever is lower. To avoid consuming all
|
|
* the memory for a given mount point, the system will always reserve a
|
|
* minimum of TMPFS_PAGES_RESERVED pages, which is also taken into account
|
|
* by this macro (see above). */
|
|
static __inline size_t
|
|
TMPFS_PAGES_MAX(struct tmpfs_mount *tmp)
|
|
{
|
|
size_t freepages;
|
|
|
|
freepages = tmpfs_mem_info();
|
|
freepages -= freepages < TMPFS_PAGES_RESERVED ?
|
|
freepages : TMPFS_PAGES_RESERVED;
|
|
|
|
return MIN(tmp->tm_pages_max, freepages + tmp->tm_pages_used);
|
|
}
|
|
|
|
/* Returns the available space for the given file system. */
|
|
#define TMPFS_META_PAGES(tmp) (howmany((tmp)->tm_nodes_inuse * (sizeof(struct tmpfs_node) \
|
|
+ sizeof(struct tmpfs_dirent)), PAGE_SIZE))
|
|
#define TMPFS_FILE_PAGES(tmp) ((tmp)->tm_pages_used)
|
|
|
|
#define TMPFS_PAGES_AVAIL(tmp) (TMPFS_PAGES_MAX(tmp) > \
|
|
TMPFS_META_PAGES(tmp)+TMPFS_FILE_PAGES(tmp)? \
|
|
TMPFS_PAGES_MAX(tmp) - TMPFS_META_PAGES(tmp) \
|
|
- TMPFS_FILE_PAGES(tmp):0)
|
|
|
|
#endif
|
|
|
|
/* --------------------------------------------------------------------- */
|
|
|
|
/*
|
|
* Macros/functions to convert from generic data structures to tmpfs
|
|
* specific ones.
|
|
*/
|
|
|
|
static inline
|
|
struct tmpfs_mount *
|
|
VFS_TO_TMPFS(struct mount *mp)
|
|
{
|
|
struct tmpfs_mount *tmp;
|
|
|
|
MPASS((mp) != NULL && (mp)->mnt_data != NULL);
|
|
tmp = (struct tmpfs_mount *)(mp)->mnt_data;
|
|
return tmp;
|
|
}
|
|
|
|
static inline
|
|
struct tmpfs_node *
|
|
VP_TO_TMPFS_NODE(struct vnode *vp)
|
|
{
|
|
struct tmpfs_node *node;
|
|
|
|
MPASS((vp) != NULL && (vp)->v_data != NULL);
|
|
node = (struct tmpfs_node *)vp->v_data;
|
|
return node;
|
|
}
|
|
|
|
static inline
|
|
struct tmpfs_node *
|
|
VP_TO_TMPFS_DIR(struct vnode *vp)
|
|
{
|
|
struct tmpfs_node *node;
|
|
|
|
node = VP_TO_TMPFS_NODE(vp);
|
|
TMPFS_VALIDATE_DIR(node);
|
|
return node;
|
|
}
|
|
|
|
#endif /* _FS_TMPFS_TMPFS_H_ */
|