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

     /*      $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: releng/11.0/sys/fs/tmpfs/tmpfs.h 277828 2015-01-28 10:37:23Z kib $
     */
    
    #ifndef _FS_TMPFS_TMPFS_H_
    #define _FS_TMPFS_TMPFS_H_
    
    #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/tree.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.
     */
    
    LIST_HEAD(tmpfs_dir_duphead, tmpfs_dirent);
    
    struct tmpfs_dirent {
            /*
             * Depending on td_cookie flag entry can be of 3 types:
             * - regular -- no hash collisions, stored in RB-Tree
             * - duphead -- synthetic linked list head for dup entries
             * - dup -- stored in linked list instead of RB-Tree
             */
            union {
                    /* regular and duphead entry types */
                    RB_ENTRY(tmpfs_dirent)          td_entries;
    
                    /* dup entry type */
                    struct {
                            LIST_ENTRY(tmpfs_dirent) entries;
                            LIST_ENTRY(tmpfs_dirent) index_entries;
                    } td_dup;
            } uh;
    
            uint32_t                        td_cookie;
            uint32_t                        td_hash;
            u_int                           td_namelen;
    
            /* Pointer to the node this entry refers to.  In case this field
             * is NULL, the node is a whiteout. */
            struct tmpfs_node *             td_node;
    
            union {
                    /*
                     * The name of the entry, allocated from a string pool.  This
                     * string is not required to be zero-terminated.
                     */
                    char *                  td_name;        /* regular, dup */
                    struct tmpfs_dir_duphead td_duphead;    /* duphead */
            } ud;
    };
    
    /* A directory in tmpfs holds a list of directory entries, which in
     * turn point to other files (which can be directories themselves).
     *
    * In tmpfs, this list is managed by a RB-Tree, whose head is defined by
    * the struct tmpfs_dir type.
    *
    * It is important 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. */
   RB_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.
    *
    * The '.', '..' and the end of directory markers have fixed cookies which
    * cannot collide with the cookies generated by other entries.  The cookies
    * for the other entries are generated based on the file name hash value or
    * unique number in case of name hash collision.
    *
    * To preserve compatibility cookies are limited to 31 bits.
    */
   
   #define TMPFS_DIRCOOKIE_DOT             0
   #define TMPFS_DIRCOOKIE_DOTDOT          1
   #define TMPFS_DIRCOOKIE_EOF             2
   #define TMPFS_DIRCOOKIE_MASK            ((off_t)0x3fffffffU)
   #define TMPFS_DIRCOOKIE_MIN             ((off_t)0x00000004U)
   #define TMPFS_DIRCOOKIE_DUP             ((off_t)0x40000000U)
   #define TMPFS_DIRCOOKIE_DUPHEAD         ((off_t)0x80000000U)
   #define TMPFS_DIRCOOKIE_DUP_MIN         TMPFS_DIRCOOKIE_DUP
   #define TMPFS_DIRCOOKIE_DUP_MAX         \
           (TMPFS_DIRCOOKIE_DUP | TMPFS_DIRCOOKIE_MASK)
   
   /*
    * 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;
           u_long                  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 tree that links the contents of
                            * the directory together. */
                           struct tmpfs_dir        tn_dirhead;
   
                           /* Head of a list the contains fake directory entries
                            * heads, i.e. entries with TMPFS_DIRCOOKIE_DUPHEAD
                            * flag. */
                           struct tmpfs_dir_duphead tn_dupindex;
   
                           /* 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. */
                           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)
   #define TMPFS_NODE_ASSERT_LOCKED(node) mtx_assert(TMPFS_NODE_MTX(node), \
       MA_OWNED)
   
   #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
   #define TMPFS_VNODE_WRECLAIM    8
   
   /*
    * 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 mount *mp, 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 *, u_int, struct tmpfs_dirent **);
   void    tmpfs_free_dirent(struct tmpfs_mount *, struct tmpfs_dirent *);
   void    tmpfs_dirent_init(struct tmpfs_dirent *, const char *, u_int);
   void    tmpfs_destroy_vobject(struct vnode *vp, vm_object_t obj);
   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_check_mtime(struct vnode *);
   void    tmpfs_dir_attach(struct vnode *, struct tmpfs_dirent *);
   void    tmpfs_dir_detach(struct vnode *, struct tmpfs_dirent *);
   void    tmpfs_dir_destroy(struct tmpfs_mount *, struct tmpfs_node *);
   struct tmpfs_dirent *   tmpfs_dir_lookup(struct tmpfs_node *node,
                               struct tmpfs_node *f,
                               struct componentname *cnp);
   int     tmpfs_dir_getdents(struct tmpfs_node *, struct uio *, int,
               u_long *, int *);
   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 *, u_long, 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 vattr *, struct ucred *cred,
               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 == len && \
       bcmp((de)->ud.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) do { \
           MPASS((node)->tn_type == VDIR); \
           MPASS((node)->tn_size % sizeof(struct tmpfs_dirent) == 0); \
   } while (0)
   
   /*
    * 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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