bsd/vfs/vfs_journal.h

   1
   2 /*
   3  * Copyright (c) 2000-2002 Apple Computer, Inc. All rights reserved.
   4  *
   5  * @APPLE_LICENSE_HEADER_START@
   6  *
   7  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   8  *
   9  * This file contains Original Code and/or Modifications of Original Code
  10  * as defined in and that are subject to the Apple Public Source License
  11  * Version 2.0 (the 'License'). You may not use this file except in
  12  * compliance with the License. Please obtain a copy of the License at
  13  * http://www.opensource.apple.com/apsl/ and read it before using this
  14  * file.
  15  *
  16  * The Original Code and all software distributed under the License are
  17  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  18  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  19  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  20  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  21  * Please see the License for the specific language governing rights and
  22  * limitations under the License.
  23  *
  24  * @APPLE_LICENSE_HEADER_END@
  25  */
  26 /*
  27  * This header contains the structures and function prototypes
  28  * for the vfs journaling code.  The data types are not meant
  29  * to be modified by user code.  Just use the functions and do
  30  * not mess around with the structs.
  31  */
  32 #ifndef _SYS_VFS_JOURNAL_H_
  33 #define _SYS_VFS_JOURNAL_H_
  34
  35 #include <sys/appleapiopts.h>
  36
  37 #ifdef __APPLE_API_UNSTABLE
  38
  39 #include <sys/types.h>
  40
  41 typedef struct block_info {
  42     off_t       bnum;                // block # on the file system device
  43     size_t      bsize;               // in bytes
  44     struct buf *bp;
  45 } block_info;
  46
  47 typedef struct block_list_header {
  48     u_int16_t   max_blocks;          // max number of blocks in this chunk
  49     u_int16_t   num_blocks;          // number of valid block numbers in block_nums
  50     int32_t     bytes_used;          // how many bytes of this tbuffer are used
  51     int32_t     checksum;            // on-disk: checksum of this header and binfo[0]
  52     int32_t     pad;                 // pad out to 16 bytes
  53     block_info  binfo[1];            // so we can reference them by name
  54 } block_list_header;
  55
  56
  57 struct journal;
  58
  59 typedef struct transaction {
  60     int                 tbuffer_size;  // in bytes
  61     char               *tbuffer;       // memory copy of the transaction
  62     block_list_header  *blhdr;         // points to the first byte of tbuffer
  63     int                 num_blhdrs;    // how many buffers we've allocated
  64     int                 total_bytes;   // total # of bytes in transaction
  65     int                 num_flushed;   // how many bytes have been flushed
  66     int                 num_killed;    // how many bytes were "killed"
  67     off_t               journal_start; // where in the journal this transaction starts
  68     off_t               journal_end;   // where in the journal this transaction ends
  69     struct journal     *jnl;           // ptr back to the journal structure
  70     struct transaction *next;          // list of tr's (either completed or to be free'd)
  71 } transaction;
  72
  73
  74 /*
  75  * This is written to block zero of the journal and it
  76  * maintains overall state about the journal.
  77  */
  78 typedef struct journal_header {
  79     int32_t        magic;
  80     int32_t        endian;
  81     volatile off_t start;         // zero-based byte offset of the start of the first transaction
  82     volatile off_t end;           // zero-based byte offset of where free space begins
  83     off_t          size;          // size in bytes of the entire journal
  84     int32_t        blhdr_size;    // size in bytes of each block_list_header in the journal
  85     int32_t        checksum;
  86     int32_t        jhdr_size;     // block size (in bytes) of the journal header
  87 } journal_header;
  88
  89 #define JOURNAL_HEADER_MAGIC  0x4a4e4c78   // 'JNLx'
  90 #define ENDIAN_MAGIC          0x12345678
  91
  92 #define OLD_JOURNAL_HEADER_MAGIC  0x4a484452   // 'JHDR'
  93
  94
  95 /*
  96  * In memory structure about the journal.
  97  */
  98 typedef struct journal {
  99     struct vnode       *jdev;              // vnode of the device where the journal lives
 100     off_t               jdev_offset;       // byte offset to the start of the journal
 101
 102     struct vnode       *fsdev;             // vnode of the file system device
 103
 104     void              (*flush)(void *arg); // fs callback to flush meta data blocks
 105     void               *flush_arg;         // arg that's passed to flush()
 106
 107     int32_t             flags;
 108     int32_t             tbuffer_size;      // default transaction buffer size
 109
 110     char               *header_buf;        // in-memory copy of the journal header
 111     journal_header     *jhdr;              // points to the first byte of header_buf
 112
 113     transaction        *cur_tr;            // for group-commit
 114     transaction        *completed_trs;     // out-of-order transactions that completed
 115     transaction        *active_tr;         // for nested transactions
 116     int32_t             nested_count;      // for nested transactions
 117     void               *owner;             // a ptr that's unique to the calling process
 118
 119     transaction        *tr_freeme;         // transaction structs that need to be free'd
 120
 121         volatile off_t      active_start;      // the active start that we only keep in memory
 122         simple_lock_data_t  old_start_lock;    // guard access
 123         volatile off_t      old_start[16];     // this is how we do lazy start update
 124
 125     semaphore_t         jsem;
 126 } journal;
 127
 128 /* internal-only journal flags (top 16 bits) */
 129 #define JOURNAL_CLOSE_PENDING     0x00010000
 130 #define JOURNAL_INVALID           0x00020000
 131
 132 /* journal_open/create options are always in the low-16 bits */
 133 #define JOURNAL_OPTION_FLAGS_MASK 0x0000ffff
 134
 135 /*
 136  * Prototypes.
 137  */
 138
 139 /*
 140  * Call journal_create() to create a new journal.  You only
 141  * call this once, typically at file system creation time.
 142  *
 143  * The "jvp" argument is the vnode where the journal is written.
 144  * The journal starts at "offset" and is "journal_size" bytes long.
 145  *
 146  * The "fsvp" argument is the vnode of your file system.  It may be
 147  * the same as "jvp".
 148  *
 149  * The "min_fs_block_size" argument is the minimum block size
 150  * (in bytes) that the file system will ever write.  Typically
 151  * this is the block size of the file system (1k, 4k, etc) but
 152  * on HFS+ it is the minimum block size of the underlying device.
 153  *
 154  * The flags argument lets you disable group commit if you
 155  * want tighter guarantees on transactions (in exchange for
 156  * lower performance).
 157  *
 158  * The tbuffer_size is the size of the transaction buffer
 159  * used by the journal. If you specify zero, the journal code
 160  * will use a reasonable defaults.  The tbuffer_size should
 161  * be an integer multiple of the min_fs_block_size.
 162  *
 163  * Returns a valid journal pointer or NULL if one could not
 164  * be created.
 165  */
 166 journal *journal_create(struct vnode *jvp,
 167                                                 off_t         offset,
 168                                                 off_t         journal_size,
 169                                                 struct vnode *fsvp,
 170                                                 size_t        min_fs_block_size,
 171                                                 int32_t       flags,
 172                                                 int32_t       tbuffer_size,
 173                                                 void        (*flush)(void *arg),
 174                                                 void         *arg);
 175
 176 /*
 177  * Call journal_open() when mounting an existing file system
 178  * that has a previously created journal.  It will take care
 179  * of validating the journal and replaying it if necessary.
 180  *
 181  * See journal_create() for a description of the arguments.
 182  *
 183  * Returns a valid journal pointer of NULL if it runs into
 184  * trouble reading/playing back the journal.
 185  */
 186 journal  *journal_open(struct vnode *jvp,
 187                                            off_t         offset,
 188                                            off_t         journal_size,
 189                                            struct vnode *fsvp,
 190                                            size_t        min_fs_block_size,
 191                                            int32_t       flags,
 192                                            int32_t       tbuffer_size,
 193                                            void        (*flush)(void *arg),
 194                                            void         *arg);
 195
 196 /*
 197  * Call journal_close() just before your file system is unmounted.
 198  * It flushes any outstanding transactions and makes sure the
 199  * journal is in a consistent state.
 200  */
 201 void      journal_close(journal *journal);
 202
 203 /*
 204  * flags for journal_create/open.  only can use
 205  * the low 16 bits for flags because internal
 206  * bits go in the high 16.
 207  */
 208 #define JOURNAL_NO_GROUP_COMMIT   0x00000001
 209 #define JOURNAL_RESET             0x00000002
 210
 211 /*
 212  * Transaction related functions.
 213  *
 214  * Before you start modifying file system meta data, you
 215  * should call journal_start_transaction().  Then before
 216  * you modify each block, call journal_modify_block_start()
 217  * and when you're done, journal_modify_block_end().  When
 218  * you've modified the last block as part of a transaction,
 219  * call journal_end_transaction() to commit the changes.
 220  *
 221  * If you decide to abort the modifications to a block you
 222  * should call journal_modify_block_abort().
 223  *
 224  * If as part of a transaction you need want to throw out
 225  * any previous copies of a block (because it got deleted)
 226  * then call journal_kill_block().  This will mark it so
 227  * that the journal does not play it back (effectively
 228  * dropping it).
 229  */
 230 int   journal_start_transaction(journal *jnl);
 231 int   journal_modify_block_start(journal *jnl, struct buf *bp);
 232 int   journal_modify_block_abort(journal *jnl, struct buf *bp);
 233 int   journal_modify_block_end(journal *jnl, struct buf *bp);
 234 int   journal_kill_block(journal *jnl, struct buf *bp);
 235 int   journal_end_transaction(journal *jnl);
 236
 237 int   journal_active(journal *jnl);
 238 int   journal_flush(journal *jnl);
 239
 240 #endif /* __APPLE_API_UNSTABLE */
 241 #endif /* !_SYS_VFS_JOURNAL_H_ */