160 lines
5.5 KiB
C
160 lines
5.5 KiB
C
/* @(#)pc_fs.h 1.1 94/10/31 SMI */
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/*
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* Copyright (c) 1989 by Sun Microsystems, Inc.
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*/
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/*
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* PC (MSDOS) compatible virtual file system.
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*
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* A main goal of the implementaion was to maintain statelessness
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* except while files are open. Thus mounting and unmounting merely
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* declared the file system name. The user may change disks at almost
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* any time without concern (just like the PC). It is assumed that when
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* files are open for writing the disk access light will be on, as a
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* warning not to change disks. The implementation must, however, detect
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* disk change and recover gracefully. It does this by comparing the
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* in core entry for a directory to the on disk entry whenever a directory
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* is searched. If a discrepancy is found active directories become root and
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* active files are marked invalid.
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*
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* There are only two type of nodes on the PC file system; files and
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* directories. These are represented by two separate vnode op vectors,
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* and they are kept in two separate tables. Files are known by the
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* disk block number and block (cluster) offset of the files directory
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* entry. Directories are known by the starting cluster number.
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*
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* The file system is locked for during each user operation. This is
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* done to simplify disk verification error conditions.
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*/
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struct pcfs {
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struct vfs *pcfs_vfs; /* vfs for this fs */
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int pcfs_flags; /* flags */
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struct vnode *pcfs_devvp; /* device mounted on */
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int pcfs_spcl; /* sectors per cluster */
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int pcfs_spt; /* sectors per track */
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int pcfs_fatsec; /* number of sec in fat */
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int pcfs_rdirsec; /* number of sec in root dir */
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daddr_t pcfs_rdirstart; /* start blkno of root dir */
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daddr_t pcfs_datastart; /* start blkno of data area */
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int pcfs_clsize; /* cluster size in bytes */
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int pcfs_ncluster; /* number of clusters in fs */
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int pcfs_nrefs; /* number of active pcnodes */
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int pcfs_frefs; /* number of active file pcnodes */
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struct buf *pcfs_fatbp; /* ptr to fat buffer */
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u_char *pcfs_fatp; /* ptr to fat data */
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struct timeval pcfs_fattime; /* time fat becomes invalid */
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struct timeval pcfs_verifytime; /* time to reverify disk */
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long pcfs_owner; /* proc index of process locking pcfs */
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long pcfs_count; /* # of pcfs locks for pcfs_owner */
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struct pcfs *pcfs_nxt; /* linked list of all mounts */
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};
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/*
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* flags
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*/
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#define PCFS_FATMOD 0x01 /* fat has been modified */
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#define PCFS_LOCKED 0x02 /* fs is locked */
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#define PCFS_WANTED 0x04 /* locked fs is wanted */
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/*
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* Disk timeout value in sec.
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* This is used to time out the in core fat and to re-verify the disk.
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* This should be less than the time it takes to change floppys
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*/
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#define PCFS_DISKTIMEOUT 2
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#define VFSTOPCFS(VFSP) ((struct pcfs *)((VFSP)->vfs_data))
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#define PCFSTOVFS(FSP) ((FSP)->pcfs_vfs)
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/*
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* special cluster numbers in fat
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*/
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#define PCF_FREECLUSTER 0x00 /* cluster is available */
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#define PCF_ERRORCLUSTER 0x01 /* error occurred allocating cluster */
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#define PCF_LASTCLUSTER 0xFF8 /* >= means last cluster in file */
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#define PCF_FIRSTCLUSTER 2 /* first data cluster number */
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/*
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* file system constants
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*/
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#define PC_MAXFATSEC 9 /* maximum number of sectors in fat */
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/*
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* file system parameter macros
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*/
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#define pc_blksize(PCFS, PCP, OFF) /* file system block size */ \
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(PCTOV(PCP)->v_flag & VROOT? \
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((OFF) >= \
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((PCFS)->pcfs_rdirsec & ~((PCFS)->pcfs_spcl - 1)) * PC_SECSIZE? \
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((PCFS)->pcfs_rdirsec & ((PCFS)->pcfs_spcl - 1)) * PC_SECSIZE: \
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(PCFS)->pcfs_clsize): \
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(PCFS)->pcfs_clsize)
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#define pc_blkoff(PCFS, OFF) /* offset within block */ \
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((OFF) & ((PCFS)->pcfs_clsize - 1))
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#define pc_lblkno(PCFS, OFF) /* logical block (cluster) no */ \
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((daddr_t)((OFF) / (PCFS)->pcfs_clsize))
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#define pc_dbtocl(PCFS, DB) /* disk blks to clusters */ \
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((int)((DB) / (PCFS)->pcfs_spcl))
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#define pc_cltodb(PCFS, CL) /* clusters to disk blks */ \
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((daddr_t)((CL) * (PCFS)->pcfs_spcl))
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#define pc_cldaddr(PCFS, CL) /* disk address for cluster */ \
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((daddr_t)((PCFS)->pcfs_datastart + \
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((CL) - PCF_FIRSTCLUSTER) * (PCFS)->pcfs_spcl))
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#define pc_daddrcl(PCFS, DADDR) /* cluster for disk address */ \
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((int)((((DADDR) - (PCFS)->pcfs_datastart) / (PCFS)->pcfs_spcl) + 2))
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#define pc_validcl(PCFS, CL) /* check that cluster no is legit */ \
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((CL) >= PCF_FIRSTCLUSTER && \
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(CL) < (PCFS)->pcfs_ncluster + PCF_FIRSTCLUSTER)
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/*
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* lock and unlock macros
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*/
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#define PC_LOCKFS(PCFS) { \
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while (((PCFS)->pcfs_flags & PCFS_LOCKED) && \
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(PCFS)->pcfs_owner != uniqpid()) { \
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(PCFS)->pcfs_flags |= PCFS_WANTED; \
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(void) sleep((caddr_t)(PCFS), PRIBIO); \
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} \
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(PCFS)->pcfs_owner = uniqpid(); \
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(PCFS)->pcfs_count++; \
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(PCFS)->pcfs_flags |= PCFS_LOCKED; \
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}
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#define PC_UNLOCKFS(PCFS) { \
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if (--(PCFS)->pcfs_count < 0) \
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panic("PC_UNLOCKFS"); \
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if ((PCFS)->pcfs_count == 0) { \
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(PCFS)->pcfs_flags &= ~PCFS_LOCKED; \
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if ((PCFS)->pcfs_flags & PCFS_WANTED) { \
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(PCFS)->pcfs_flags &= ~PCFS_WANTED; \
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wakeup((caddr_t)(PCFS)); \
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} \
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} \
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}
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/*
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* external routines.
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*/
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extern int pc_lockfs(); /* lock fs and get fat */
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extern void pc_unlockfs(); /* ulock the fs */
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extern int pc_getfat(); /* get fat from disk */
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extern void pc_invalfat(); /* invalidate incore fat */
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extern int pc_syncfat(); /* sync fat to disk */
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extern int pc_freeclusters(); /* number of free clusters in the fs */
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extern short pc_alloccluster(); /* allocate a new cluster */
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extern void pc_setcluster(); /* set the next cluster fat */
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/*
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* debugging
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*/
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extern int pcfsdebuglevel;
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#define PCFSDEBUG(X) if (X <= pcfsdebuglevel)
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