1 /* 2 * linux/include/linux/jbd.h 3 * 4 * Written by Stephen C. Tweedie <sct (at) redhat.com> 5 * 6 * Copyright 1998-2000 Red Hat, Inc --- All Rights Reserved 7 * 8 * This file is part of the Linux kernel and is made available under 9 * the terms of the GNU General Public License, version 2, or at your 10 * option, any later version, incorporated herein by reference. 11 * 12 * Definitions for transaction data structures for the buffer cache 13 * filesystem journaling support. 14 */ 15 16 #ifndef _LINUX_JBD_H 17 #define _LINUX_JBD_H 18 19 /* Allow this file to be included directly into e2fsprogs */ 20 #include "jfs_compat.h" 21 #define JFS_DEBUG 22 #define jfs_debug jbd_debug 23 24 #define journal_oom_retry 1 25 26 /* 27 * Define JBD_PARANIOD_IOFAIL to cause a kernel BUG() if ext3 finds 28 * certain classes of error which can occur due to failed IOs. Under 29 * normal use we want ext3 to continue after such errors, because 30 * hardware _can_ fail, but for debugging purposes when running tests on 31 * known-good hardware we may want to trap these errors. 32 */ 33 #undef JBD_PARANOID_IOFAIL 34 35 /* 36 * The default maximum commit age, in seconds. 37 */ 38 #define JBD_DEFAULT_MAX_COMMIT_AGE 5 39 40 #ifdef CONFIG_JBD_DEBUG 41 /* 42 * Define JBD_EXPENSIVE_CHECKING to enable more expensive internal 43 * consistency checks. By default we don't do this unless 44 * CONFIG_JBD_DEBUG is on. 45 */ 46 #define JBD_EXPENSIVE_CHECKING 47 extern u8 journal_enable_debug; 48 49 #define jbd_debug(n, f, a...) \ 50 do { \ 51 if ((n) <= journal_enable_debug) { \ 52 printk (KERN_DEBUG "(%s, %d): %s: ", \ 53 __FILE__, __LINE__, __FUNCTION__); \ 54 printk (f, ## a); \ 55 } \ 56 } while (0) 57 #else 58 #define jbd_debug(f, a...) /**/ 59 #endif 60 61 static __inline__ void *jbd_alloc(size_t size, gfp_t flags) 62 { 63 return (void *)__get_free_pages(flags, get_order(size)); 64 } 65 66 static __inline__ void jbd_free(void *ptr, size_t size) 67 { 68 free_pages((unsigned long)ptr, get_order(size)); 69 }; 70 71 #define JFS_MIN_JOURNAL_BLOCKS 1024 72 73 74 /* 75 * Internal structures used by the logging mechanism: 76 */ 77 78 #define JFS_MAGIC_NUMBER 0xc03b3998U /* The first 4 bytes of /dev/random! */ 79 80 /* 81 * On-disk structures 82 */ 83 84 /* 85 * Descriptor block types: 86 */ 87 88 #define JFS_DESCRIPTOR_BLOCK 1 89 #define JFS_COMMIT_BLOCK 2 90 #define JFS_SUPERBLOCK_V1 3 91 #define JFS_SUPERBLOCK_V2 4 92 #define JFS_REVOKE_BLOCK 5 93 94 /* 95 * Standard header for all descriptor blocks: 96 */ 97 typedef struct journal_header_s 98 { 99 __be32 h_magic; 100 __be32 h_blocktype; 101 __be32 h_sequence; 102 } journal_header_t; 103 104 105 /* 106 * The block tag: used to describe a single buffer in the journal 107 */ 108 typedef struct journal_block_tag_s 109 { 110 __be32 t_blocknr; /* The on-disk block number */ 111 __be32 t_flags; /* See below */ 112 } journal_block_tag_t; 113 114 /* 115 * The revoke descriptor: used on disk to describe a series of blocks to 116 * be revoked from the log 117 */ 118 typedef struct journal_revoke_header_s 119 { 120 journal_header_t r_header; 121 __be32 r_count; /* Count of bytes used in the block */ 122 } journal_revoke_header_t; 123 124 125 /* Definitions for the journal tag flags word: */ 126 #define JFS_FLAG_ESCAPE 1 /* on-disk block is escaped */ 127 #define JFS_FLAG_SAME_UUID 2 /* block has same uuid as previous */ 128 #define JFS_FLAG_DELETED 4 /* block deleted by this transaction */ 129 #define JFS_FLAG_LAST_TAG 8 /* last tag in this descriptor block */ 130 131 132 /* 133 * The journal superblock. All fields are in big-endian byte order. 134 */ 135 typedef struct journal_superblock_s 136 { 137 /* 0x0000 */ 138 journal_header_t s_header; 139 140 /* 0x000C */ 141 /* Static information describing the journal */ 142 __be32 s_blocksize; /* journal device blocksize */ 143 __be32 s_maxlen; /* total blocks in journal file */ 144 __be32 s_first; /* first block of log information */ 145 146 /* 0x0018 */ 147 /* Dynamic information describing the current state of the log */ 148 __be32 s_sequence; /* first commit ID expected in log */ 149 __be32 s_start; /* blocknr of start of log */ 150 151 /* 0x0020 */ 152 /* Error value, as set by journal_abort(). */ 153 __be32 s_errno; 154 155 /* 0x0024 */ 156 /* Remaining fields are only valid in a version-2 superblock */ 157 __be32 s_feature_compat; /* compatible feature set */ 158 __be32 s_feature_incompat; /* incompatible feature set */ 159 __be32 s_feature_ro_compat; /* readonly-compatible feature set */ 160 /* 0x0030 */ 161 __u8 s_uuid[16]; /* 128-bit uuid for journal */ 162 163 /* 0x0040 */ 164 __be32 s_nr_users; /* Nr of filesystems sharing log */ 165 166 __be32 s_dynsuper; /* Blocknr of dynamic superblock copy*/ 167 168 /* 0x0048 */ 169 __be32 s_max_transaction; /* Limit of journal blocks per trans.*/ 170 __be32 s_max_trans_data; /* Limit of data blocks per trans. */ 171 172 /* 0x0050 */ 173 __u32 s_padding[44]; 174 175 /* 0x0100 */ 176 __u8 s_users[16*48]; /* ids of all fs'es sharing the log */ 177 /* 0x0400 */ 178 } journal_superblock_t; 179 180 #define JFS_HAS_COMPAT_FEATURE(j,mask) \ 181 ((j)->j_format_version >= 2 && \ 182 ((j)->j_superblock->s_feature_compat & cpu_to_be32((mask)))) 183 #define JFS_HAS_RO_COMPAT_FEATURE(j,mask) \ 184 ((j)->j_format_version >= 2 && \ 185 ((j)->j_superblock->s_feature_ro_compat & cpu_to_be32((mask)))) 186 #define JFS_HAS_INCOMPAT_FEATURE(j,mask) \ 187 ((j)->j_format_version >= 2 && \ 188 ((j)->j_superblock->s_feature_incompat & cpu_to_be32((mask)))) 189 190 #define JFS_FEATURE_INCOMPAT_REVOKE 0x00000001 191 192 /* Features known to this kernel version: */ 193 #define JFS_KNOWN_COMPAT_FEATURES 0 194 #define JFS_KNOWN_ROCOMPAT_FEATURES 0 195 #define JFS_KNOWN_INCOMPAT_FEATURES JFS_FEATURE_INCOMPAT_REVOKE 196 197 198 /* Comparison functions for transaction IDs: perform comparisons using 199 * modulo arithmetic so that they work over sequence number wraps. */ 200 201 static __inline__ int tid_gt(tid_t x, tid_t y) 202 { 203 int difference = (x - y); 204 return (difference > 0); 205 } 206 207 static __inline__ int tid_geq(tid_t x, tid_t y) 208 { 209 int difference = (x - y); 210 return (difference >= 0); 211 } 212 213 extern int journal_blocks_per_page(struct inode *inode); 214 215 /* 216 * Return the minimum number of blocks which must be free in the journal 217 * before a new transaction may be started. Must be called under j_state_lock. 218 */ 219 static __inline__ int jbd_space_needed(journal_t *journal) 220 { 221 int nblocks = journal->j_max_transaction_buffers; 222 if (journal->j_committing_transaction) 223 nblocks += journal->j_committing_transaction-> 224 t_outstanding_credits; 225 return nblocks; 226 } 227 228 /* 229 * Definitions which augment the buffer_head layer 230 */ 231 232 /* journaling buffer types */ 233 #define BJ_None 0 /* Not journaled */ 234 #define BJ_SyncData 1 /* Normal data: flush before commit */ 235 #define BJ_Metadata 2 /* Normal journaled metadata */ 236 #define BJ_Forget 3 /* Buffer superseded by this transaction */ 237 #define BJ_IO 4 /* Buffer is for temporary IO use */ 238 #define BJ_Shadow 5 /* Buffer contents being shadowed to the log */ 239 #define BJ_LogCtl 6 /* Buffer contains log descriptors */ 240 #define BJ_Reserved 7 /* Buffer is reserved for access by journal */ 241 #define BJ_Locked 8 /* Locked for I/O during commit */ 242 #define BJ_Types 9 243 244 extern int jbd_blocks_per_page(struct inode *inode); 245 246 247 #endif /* _LINUX_JBD_H */ 248
