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freebsd-dev/sys/fs/tmpfs/tmpfs.h
Jaakko Heinonen c5ab5ce345 tmpfs: Allow update mounts only for certain options. 
Since r230208 update mounts were allowed if the list of mount options
contained the "export" option. This is not correct as tmpfs doesn't
really support updating all options.

Reviewed by:	kevlo, trociny
2012-04-16 18:07:42 +00:00

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