The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]

FreeBSD/Linux Kernel Cross Reference
sys/fs/tmpfs/tmpfs.h

Version: -  FREEBSD  -  FREEBSD-13-STABLE  -  FREEBSD-13-0  -  FREEBSD-12-STABLE  -  FREEBSD-12-0  -  FREEBSD-11-STABLE  -  FREEBSD-11-0  -  FREEBSD-10-STABLE  -  FREEBSD-10-0  -  FREEBSD-9-STABLE  -  FREEBSD-9-0  -  FREEBSD-8-STABLE  -  FREEBSD-8-0  -  FREEBSD-7-STABLE  -  FREEBSD-7-0  -  FREEBSD-6-STABLE  -  FREEBSD-6-0  -  FREEBSD-5-STABLE  -  FREEBSD-5-0  -  FREEBSD-4-STABLE  -  FREEBSD-3-STABLE  -  FREEBSD22  -  l41  -  OPENBSD  -  linux-2.6  -  MK84  -  PLAN9  -  xnu-8792 
SearchContext: -  none  -  3  -  10 

    1 /*      $NetBSD: tmpfs.h,v 1.26 2007/02/22 06:37:00 thorpej Exp $       */
    2 
    3 /*-
    4  * Copyright (c) 2005, 2006 The NetBSD Foundation, Inc.
    5  * All rights reserved.
    6  *
    7  * This code is derived from software contributed to The NetBSD Foundation
    8  * by Julio M. Merino Vidal, developed as part of Google's Summer of Code
    9  * 2005 program.
   10  *
   11  * Redistribution and use in source and binary forms, with or without
   12  * modification, are permitted provided that the following conditions
   13  * are met:
   14  * 1. Redistributions of source code must retain the above copyright
   15  *    notice, this list of conditions and the following disclaimer.
   16  * 2. Redistributions in binary form must reproduce the above copyright
   17  *    notice, this list of conditions and the following disclaimer in the
   18  *    documentation and/or other materials provided with the distribution.
   19  *
   20  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
   21  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   22  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   23  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
   24  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   25  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   26  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   27  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   28  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   29  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   30  * POSSIBILITY OF SUCH DAMAGE.
   31  *
   32  * $FreeBSD$
   33  */
   34 
   35 #ifndef _FS_TMPFS_TMPFS_H_
   36 #define _FS_TMPFS_TMPFS_H_
   37 
   38 /* ---------------------------------------------------------------------
   39  * KERNEL-SPECIFIC DEFINITIONS
   40  * --------------------------------------------------------------------- */
   41 #include <sys/dirent.h>
   42 #include <sys/mount.h>
   43 #include <sys/queue.h>
   44 #include <sys/vnode.h>
   45 #include <sys/file.h>
   46 #include <sys/lock.h>
   47 #include <sys/mutex.h>
   48 
   49 /* --------------------------------------------------------------------- */
   50 #include <sys/malloc.h>
   51 #include <sys/systm.h>
   52 #include <sys/vmmeter.h>
   53 #include <vm/swap_pager.h>
   54 
   55 MALLOC_DECLARE(M_TMPFSMNT);
   56 MALLOC_DECLARE(M_TMPFSNAME);
   57 
   58 /* --------------------------------------------------------------------- */
   59 
   60 /*
   61  * Internal representation of a tmpfs directory entry.
   62  */
   63 struct tmpfs_dirent {
   64         TAILQ_ENTRY(tmpfs_dirent)       td_entries;
   65 
   66         /* Length of the name stored in this directory entry.  This avoids
   67          * the need to recalculate it every time the name is used. */
   68         uint16_t                        td_namelen;
   69 
   70         /* The name of the entry, allocated from a string pool.  This
   71         * string is not required to be zero-terminated; therefore, the
   72         * td_namelen field must always be used when accessing its value. */
   73         char *                          td_name;
   74 
   75         /* Pointer to the node this entry refers to. */
   76         struct tmpfs_node *             td_node;
   77 };
   78 
   79 /* A directory in tmpfs holds a sorted list of directory entries, which in
   80  * turn point to other files (which can be directories themselves).
   81  *
   82  * In tmpfs, this list is managed by a tail queue, whose head is defined by
   83  * the struct tmpfs_dir type.
   84  *
   85  * It is imporant to notice that directories do not have entries for . and
   86  * .. as other file systems do.  These can be generated when requested
   87  * based on information available by other means, such as the pointer to
   88  * the node itself in the former case or the pointer to the parent directory
   89  * in the latter case.  This is done to simplify tmpfs's code and, more
   90  * importantly, to remove redundancy. */
   91 TAILQ_HEAD(tmpfs_dir, tmpfs_dirent);
   92 
   93 /* Each entry in a directory has a cookie that identifies it.  Cookies
   94  * supersede offsets within directories because, given how tmpfs stores
   95  * directories in memory, there is no such thing as an offset.  (Emulating
   96  * a real offset could be very difficult.)
   97  * 
   98  * The '.', '..' and the end of directory markers have fixed cookies which
   99  * cannot collide with the cookies generated by other entries.  The cookies
  100  * fot the other entries are generated based on the memory address on which
  101  * stores their information is stored.
  102  *
  103  * Ideally, using the entry's memory pointer as the cookie would be enough
  104  * to represent it and it wouldn't cause collisions in any system.
  105  * Unfortunately, this results in "offsets" with very large values which
  106  * later raise problems in the Linux compatibility layer (and maybe in other
  107  * places) as described in PR kern/32034.  Hence we need to workaround this
  108  * with a rather ugly hack.
  109  *
  110  * Linux 32-bit binaries, unless built with _FILE_OFFSET_BITS=64, have off_t
  111  * set to 'long', which is a 32-bit *signed* long integer.  Regardless of
  112  * the macro value, GLIBC (2.3 at least) always uses the getdents64
  113  * system call (when calling readdir) which internally returns off64_t
  114  * offsets.  In order to make 32-bit binaries work, *GLIBC* converts the
  115  * 64-bit values returned by the kernel to 32-bit ones and aborts with
  116  * EOVERFLOW if the conversion results in values that won't fit in 32-bit
  117  * integers (which it assumes is because the directory is extremely large).
  118  * This wouldn't cause problems if we were dealing with unsigned integers,
  119  * but as we have signed integers, this check fails due to sign expansion.
  120  *
  121  * For example, consider that the kernel returns the 0xc1234567 cookie to
  122  * userspace in a off64_t integer.  Later on, GLIBC casts this value to
  123  * off_t (remember, signed) with code similar to:
  124  *     system call returns the offset in kernel_value;
  125  *     off_t casted_value = kernel_value;
  126  *     if (sizeof(off_t) != sizeof(off64_t) &&
  127  *         kernel_value != casted_value)
  128  *             error!
  129  * In this case, casted_value still has 0xc1234567, but when it is compared
  130  * for equality against kernel_value, it is promoted to a 64-bit integer and
  131  * becomes 0xffffffffc1234567, which is different than 0x00000000c1234567.
  132  * Then, GLIBC assumes this is because the directory is very large.
  133  *
  134  * Given that all the above happens in user-space, we have no control over
  135  * it; therefore we must workaround the issue here.  We do this by
  136  * truncating the pointer value to a 32-bit integer and hope that there
  137  * won't be collisions.  In fact, this will not cause any problems in
  138  * 32-bit platforms but some might arise in 64-bit machines (I'm not sure
  139  * if they can happen at all in practice).
  140  *
  141  * XXX A nicer solution shall be attempted. */
  142 #ifdef _KERNEL
  143 #define TMPFS_DIRCOOKIE_DOT     0
  144 #define TMPFS_DIRCOOKIE_DOTDOT  1
  145 #define TMPFS_DIRCOOKIE_EOF     2
  146 static __inline
  147 off_t
  148 tmpfs_dircookie(struct tmpfs_dirent *de)
  149 {
  150         off_t cookie;
  151 
  152         cookie = ((off_t)(uintptr_t)de >> 1) & 0x7FFFFFFF;
  153         MPASS(cookie != TMPFS_DIRCOOKIE_DOT);
  154         MPASS(cookie != TMPFS_DIRCOOKIE_DOTDOT);
  155         MPASS(cookie != TMPFS_DIRCOOKIE_EOF);
  156 
  157         return cookie;
  158 }
  159 #endif
  160 
  161 /* --------------------------------------------------------------------- */
  162 
  163 /*
  164  * Internal representation of a tmpfs file system node.
  165  *
  166  * This structure is splitted in two parts: one holds attributes common
  167  * to all file types and the other holds data that is only applicable to
  168  * a particular type.  The code must be careful to only access those
  169  * attributes that are actually allowed by the node's type.
  170  *
  171  *
  172  * Below is the key of locks used to protected the fields in the following
  173  * structures.
  174  *
  175  */
  176 struct tmpfs_node {
  177         /* Doubly-linked list entry which links all existing nodes for a
  178          * single file system.  This is provided to ease the removal of
  179          * all nodes during the unmount operation. */
  180         LIST_ENTRY(tmpfs_node)  tn_entries;
  181 
  182         /* The node's type.  Any of 'VBLK', 'VCHR', 'VDIR', 'VFIFO',
  183          * 'VLNK', 'VREG' and 'VSOCK' is allowed.  The usage of vnode
  184          * types instead of a custom enumeration is to make things simpler
  185          * and faster, as we do not need to convert between two types. */
  186         enum vtype              tn_type;
  187 
  188         /* Node identifier. */
  189         ino_t                   tn_id;
  190 
  191         /* Node's internal status.  This is used by several file system
  192          * operations to do modifications to the node in a delayed
  193          * fashion. */
  194         int                     tn_status;
  195 #define TMPFS_NODE_ACCESSED     (1 << 1)
  196 #define TMPFS_NODE_MODIFIED     (1 << 2)
  197 #define TMPFS_NODE_CHANGED      (1 << 3)
  198 
  199         /* The node size.  It does not necessarily match the real amount
  200          * of memory consumed by it. */
  201         off_t                   tn_size;
  202 
  203         /* Generic node attributes. */
  204         uid_t                   tn_uid;
  205         gid_t                   tn_gid;
  206         mode_t                  tn_mode;
  207         int                     tn_flags;
  208         nlink_t                 tn_links;
  209         struct timespec         tn_atime;
  210         struct timespec         tn_mtime;
  211         struct timespec         tn_ctime;
  212         struct timespec         tn_birthtime;
  213         unsigned long           tn_gen;
  214 
  215         /* As there is a single vnode for each active file within the
  216          * system, care has to be taken to avoid allocating more than one
  217          * vnode per file.  In order to do this, a bidirectional association
  218          * is kept between vnodes and nodes.
  219          *
  220          * Whenever a vnode is allocated, its v_data field is updated to
  221          * point to the node it references.  At the same time, the node's
  222          * tn_vnode field is modified to point to the new vnode representing
  223          * it.  Further attempts to allocate a vnode for this same node will
  224          * result in returning a new reference to the value stored in
  225          * tn_vnode.
  226          *
  227          * May be NULL when the node is unused (that is, no vnode has been
  228          * allocated for it or it has been reclaimed). */
  229         struct vnode *          tn_vnode;
  230 
  231         /* interlock to protect tn_vpstate */
  232         struct mtx      tn_interlock;
  233 
  234         /* Identify if current node has vnode assiocate with
  235          * or allocating vnode.
  236          */
  237         int             tn_vpstate;
  238 
  239         /* misc data field for different tn_type node */
  240         union {
  241                 /* Valid when tn_type == VBLK || tn_type == VCHR. */
  242                 dev_t                   tn_rdev;
  243 
  244                 /* Valid when tn_type == VDIR. */
  245                 struct tn_dir{
  246                         /* Pointer to the parent directory.  The root
  247                          * directory has a pointer to itself in this field;
  248                          * this property identifies the root node. */
  249                         struct tmpfs_node *     tn_parent;
  250 
  251                         /* Head of a tail-queue that links the contents of
  252                          * the directory together.  See above for a
  253                          * description of its contents. */
  254                         struct tmpfs_dir        tn_dirhead;
  255 
  256                         /* Number and pointer of the first directory entry
  257                          * returned by the readdir operation if it were
  258                          * called again to continue reading data from the
  259                          * same directory as before.  This is used to speed
  260                          * up reads of long directories, assuming that no
  261                          * more than one read is in progress at a given time.
  262                          * Otherwise, these values are discarded and a linear
  263                          * scan is performed from the beginning up to the
  264                          * point where readdir starts returning values. */
  265                         off_t                   tn_readdir_lastn;
  266                         struct tmpfs_dirent *   tn_readdir_lastp;
  267                 }tn_dir;
  268 
  269                 /* Valid when tn_type == VLNK. */
  270                 /* The link's target, allocated from a string pool. */
  271                 char *                  tn_link;
  272 
  273                 /* Valid when tn_type == VREG. */
  274                 struct tn_reg {
  275                         /* The contents of regular files stored in a tmpfs
  276                          * file system are represented by a single anonymous
  277                          * memory object (aobj, for short).  The aobj provides
  278                          * direct access to any position within the file,
  279                          * because its contents are always mapped in a
  280                          * contiguous region of virtual memory.  It is a task
  281                          * of the memory management subsystem (see uvm(9)) to
  282                          * issue the required page ins or page outs whenever
  283                          * a position within the file is accessed. */
  284                         vm_object_t             tn_aobj;
  285                         size_t                  tn_aobj_pages;
  286 
  287                 }tn_reg;
  288 
  289                 /* Valid when tn_type = VFIFO */
  290                 struct tn_fifo {
  291                         fo_rdwr_t               *tn_fo_read;
  292                         fo_rdwr_t               *tn_fo_write;
  293                 }tn_fifo;
  294         }tn_spec;
  295 };
  296 LIST_HEAD(tmpfs_node_list, tmpfs_node);
  297 
  298 #define tn_rdev tn_spec.tn_rdev
  299 #define tn_dir tn_spec.tn_dir
  300 #define tn_link tn_spec.tn_link
  301 #define tn_reg tn_spec.tn_reg
  302 #define tn_fifo tn_spec.tn_fifo
  303 
  304 #define TMPFS_NODE_LOCK(node) mtx_lock(&(node)->tn_interlock)
  305 #define TMPFS_NODE_UNLOCK(node) mtx_unlock(&(node)->tn_interlock)
  306 #define        TMPFS_NODE_MTX(node) (&(node)->tn_interlock)
  307 
  308 #define TMPFS_VNODE_ALLOCATING  1
  309 #define TMPFS_VNODE_WANT        2
  310 /* --------------------------------------------------------------------- */
  311 
  312 /*
  313  * Internal representation of a tmpfs mount point.
  314  */
  315 struct tmpfs_mount {
  316         /* Maximum number of memory pages available for use by the file
  317          * system, set during mount time.  This variable must never be
  318          * used directly as it may be bigger than the current amount of
  319          * free memory; in the extreme case, it will hold the SIZE_MAX
  320          * value.  Instead, use the TMPFS_PAGES_MAX macro. */
  321         size_t                  tm_pages_max;
  322 
  323         /* Number of pages in use by the file system.  Cannot be bigger
  324          * than the value returned by TMPFS_PAGES_MAX in any case. */
  325         size_t                  tm_pages_used;
  326 
  327         /* Pointer to the node representing the root directory of this
  328          * file system. */
  329         struct tmpfs_node *     tm_root;
  330 
  331         /* Maximum number of possible nodes for this file system; set
  332          * during mount time.  We need a hard limit on the maximum number
  333          * of nodes to avoid allocating too much of them; their objects
  334          * cannot be released until the file system is unmounted.
  335          * Otherwise, we could easily run out of memory by creating lots
  336          * of empty files and then simply removing them. */
  337         ino_t                   tm_nodes_max;
  338 
  339         /* unrhdr used to allocate inode numbers */
  340         struct unrhdr *         tm_ino_unr;
  341 
  342         /* Number of nodes currently that are in use. */
  343         ino_t                   tm_nodes_inuse;
  344 
  345         /* maximum representable file size */
  346         u_int64_t               tm_maxfilesize;
  347 
  348         /* Nodes are organized in two different lists.  The used list
  349          * contains all nodes that are currently used by the file system;
  350          * i.e., they refer to existing files.  The available list contains
  351          * all nodes that are currently available for use by new files.
  352          * Nodes must be kept in this list (instead of deleting them)
  353          * because we need to keep track of their generation number (tn_gen
  354          * field).
  355          *
  356          * Note that nodes are lazily allocated: if the available list is
  357          * empty and we have enough space to create more nodes, they will be
  358          * created and inserted in the used list.  Once these are released,
  359          * they will go into the available list, remaining alive until the
  360          * file system is unmounted. */
  361         struct tmpfs_node_list  tm_nodes_used;
  362 
  363         /* All node lock to protect the node list and tmp_pages_used */
  364         struct mtx allnode_lock;
  365 
  366         /* Pools used to store file system meta data.  These are not shared
  367          * across several instances of tmpfs for the reasons described in
  368          * tmpfs_pool.c. */
  369         uma_zone_t              tm_dirent_pool;
  370         uma_zone_t              tm_node_pool;
  371 };
  372 #define TMPFS_LOCK(tm) mtx_lock(&(tm)->allnode_lock)
  373 #define TMPFS_UNLOCK(tm) mtx_unlock(&(tm)->allnode_lock)
  374 
  375 /* --------------------------------------------------------------------- */
  376 
  377 /*
  378  * This structure maps a file identifier to a tmpfs node.  Used by the
  379  * NFS code.
  380  */
  381 struct tmpfs_fid {
  382         uint16_t                tf_len;
  383         uint16_t                tf_pad;
  384         ino_t                   tf_id;
  385         unsigned long           tf_gen;
  386 };
  387 
  388 /* --------------------------------------------------------------------- */
  389 
  390 #ifdef _KERNEL
  391 /*
  392  * Prototypes for tmpfs_subr.c.
  393  */
  394 
  395 int     tmpfs_alloc_node(struct tmpfs_mount *, enum vtype,
  396             uid_t uid, gid_t gid, mode_t mode, struct tmpfs_node *,
  397             char *, dev_t, struct thread *, struct tmpfs_node **);
  398 void    tmpfs_free_node(struct tmpfs_mount *, struct tmpfs_node *);
  399 int     tmpfs_alloc_dirent(struct tmpfs_mount *, struct tmpfs_node *,
  400             const char *, uint16_t, struct tmpfs_dirent **);
  401 void    tmpfs_free_dirent(struct tmpfs_mount *, struct tmpfs_dirent *,
  402             boolean_t);
  403 int     tmpfs_alloc_vp(struct mount *, struct tmpfs_node *, int,
  404             struct vnode **, struct thread *);
  405 void    tmpfs_free_vp(struct vnode *);
  406 int     tmpfs_alloc_file(struct vnode *, struct vnode **, struct vattr *,
  407             struct componentname *, char *);
  408 void    tmpfs_dir_attach(struct vnode *, struct tmpfs_dirent *);
  409 void    tmpfs_dir_detach(struct vnode *, struct tmpfs_dirent *);
  410 struct tmpfs_dirent *   tmpfs_dir_lookup(struct tmpfs_node *node,
  411                             struct tmpfs_node *f,
  412                             struct componentname *cnp);
  413 int     tmpfs_dir_getdotdent(struct tmpfs_node *, struct uio *);
  414 int     tmpfs_dir_getdotdotdent(struct tmpfs_node *, struct uio *);
  415 struct tmpfs_dirent *   tmpfs_dir_lookupbycookie(struct tmpfs_node *, off_t);
  416 int     tmpfs_dir_getdents(struct tmpfs_node *, struct uio *, off_t *);
  417 int     tmpfs_reg_resize(struct vnode *, off_t);
  418 int     tmpfs_chflags(struct vnode *, int, struct ucred *, struct thread *);
  419 int     tmpfs_chmod(struct vnode *, mode_t, struct ucred *, struct thread *);
  420 int     tmpfs_chown(struct vnode *, uid_t, gid_t, struct ucred *,
  421             struct thread *);
  422 int     tmpfs_chsize(struct vnode *, u_quad_t, struct ucred *, struct thread *);
  423 int     tmpfs_chtimes(struct vnode *, struct timespec *, struct timespec *,
  424             struct timespec *, int, struct ucred *, struct thread *);
  425 void    tmpfs_itimes(struct vnode *, const struct timespec *,
  426             const struct timespec *);
  427 
  428 void    tmpfs_update(struct vnode *);
  429 int     tmpfs_truncate(struct vnode *, off_t);
  430 
  431 /* --------------------------------------------------------------------- */
  432 
  433 /*
  434  * Convenience macros to simplify some logical expressions.
  435  */
  436 #define IMPLIES(a, b) (!(a) || (b))
  437 #define IFF(a, b) (IMPLIES(a, b) && IMPLIES(b, a))
  438 
  439 /* --------------------------------------------------------------------- */
  440 
  441 /*
  442  * Checks that the directory entry pointed by 'de' matches the name 'name'
  443  * with a length of 'len'.
  444  */
  445 #define TMPFS_DIRENT_MATCHES(de, name, len) \
  446     (de->td_namelen == (uint16_t)len && \
  447     memcmp((de)->td_name, (name), (de)->td_namelen) == 0)
  448 
  449 /* --------------------------------------------------------------------- */
  450 
  451 /*
  452  * Ensures that the node pointed by 'node' is a directory and that its
  453  * contents are consistent with respect to directories.
  454  */
  455 #define TMPFS_VALIDATE_DIR(node) \
  456     MPASS((node)->tn_type == VDIR); \
  457     MPASS((node)->tn_size % sizeof(struct tmpfs_dirent) == 0); \
  458     MPASS((node)->tn_dir.tn_readdir_lastp == NULL || \
  459         tmpfs_dircookie((node)->tn_dir.tn_readdir_lastp) == (node)->tn_dir.tn_readdir_lastn);
  460 
  461 /* --------------------------------------------------------------------- */
  462 
  463 /*
  464  * Memory management stuff.
  465  */
  466 
  467 /* Amount of memory pages to reserve for the system (e.g., to not use by
  468  * tmpfs).
  469  * XXX: Should this be tunable through sysctl, for instance? */
  470 #define TMPFS_PAGES_RESERVED (4 * 1024 * 1024 / PAGE_SIZE)
  471 
  472 /*
  473  * Returns information about the number of available memory pages,
  474  * including physical and virtual ones.
  475  *
  476  * If 'total' is TRUE, the value returned is the total amount of memory
  477  * pages configured for the system (either in use or free).
  478  * If it is FALSE, the value returned is the amount of free memory pages.
  479  *
  480  * Remember to remove TMPFS_PAGES_RESERVED from the returned value to avoid
  481  * excessive memory usage.
  482  *
  483  */
  484 static __inline size_t
  485 tmpfs_mem_info(void)
  486 {
  487         size_t size;
  488 
  489         size = swap_pager_avail + cnt.v_free_count + cnt.v_inactive_count;
  490         size -= size > cnt.v_wire_count ? cnt.v_wire_count : size;
  491         return size;
  492 }
  493 
  494 /* Returns the maximum size allowed for a tmpfs file system.  This macro
  495  * must be used instead of directly retrieving the value from tm_pages_max.
  496  * The reason is that the size of a tmpfs file system is dynamic: it lets
  497  * the user store files as long as there is enough free memory (including
  498  * physical memory and swap space).  Therefore, the amount of memory to be
  499  * used is either the limit imposed by the user during mount time or the
  500  * amount of available memory, whichever is lower.  To avoid consuming all
  501  * the memory for a given mount point, the system will always reserve a
  502  * minimum of TMPFS_PAGES_RESERVED pages, which is also taken into account
  503  * by this macro (see above). */
  504 static __inline size_t
  505 TMPFS_PAGES_MAX(struct tmpfs_mount *tmp)
  506 {
  507         size_t freepages;
  508 
  509         freepages = tmpfs_mem_info();
  510         freepages -= freepages < TMPFS_PAGES_RESERVED ?
  511             freepages : TMPFS_PAGES_RESERVED;
  512 
  513         return MIN(tmp->tm_pages_max, freepages + tmp->tm_pages_used);
  514 }
  515 
  516 /* Returns the available space for the given file system. */
  517 #define TMPFS_META_PAGES(tmp) (howmany((tmp)->tm_nodes_inuse * (sizeof(struct tmpfs_node) \
  518                                 + sizeof(struct tmpfs_dirent)), PAGE_SIZE))
  519 #define TMPFS_FILE_PAGES(tmp) ((tmp)->tm_pages_used)
  520 
  521 #define TMPFS_PAGES_AVAIL(tmp) (TMPFS_PAGES_MAX(tmp) > \
  522                         TMPFS_META_PAGES(tmp)+TMPFS_FILE_PAGES(tmp)? \
  523                         TMPFS_PAGES_MAX(tmp) - TMPFS_META_PAGES(tmp) \
  524                         - TMPFS_FILE_PAGES(tmp):0)
  525 
  526 #endif
  527 
  528 /* --------------------------------------------------------------------- */
  529 
  530 /*
  531  * Macros/functions to convert from generic data structures to tmpfs
  532  * specific ones.
  533  */
  534 
  535 static inline
  536 struct tmpfs_mount *
  537 VFS_TO_TMPFS(struct mount *mp)
  538 {
  539         struct tmpfs_mount *tmp;
  540 
  541         MPASS((mp) != NULL && (mp)->mnt_data != NULL);
  542         tmp = (struct tmpfs_mount *)(mp)->mnt_data;
  543         return tmp;
  544 }
  545 
  546 static inline
  547 struct tmpfs_node *
  548 VP_TO_TMPFS_NODE(struct vnode *vp)
  549 {
  550         struct tmpfs_node *node;
  551 
  552         MPASS((vp) != NULL && (vp)->v_data != NULL);
  553         node = (struct tmpfs_node *)vp->v_data;
  554         return node;
  555 }
  556 
  557 static inline
  558 struct tmpfs_node *
  559 VP_TO_TMPFS_DIR(struct vnode *vp)
  560 {
  561         struct tmpfs_node *node;
  562 
  563         node = VP_TO_TMPFS_NODE(vp);
  564         TMPFS_VALIDATE_DIR(node);
  565         return node;
  566 }
  567 
  568 #endif /* _FS_TMPFS_TMPFS_H_ */

Cache object: c67385eaa96b0fa9ecf16a33011bc50a


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]


This page is part of the FreeBSD/Linux Linux Kernel Cross-Reference, and was automatically generated using a modified version of the LXR engine.