/* $Id: msdosfs_fat.c,v 1.9 1995/11/07 14:06:42 phk Exp $ */ /* $NetBSD: msdosfs_fat.c,v 1.12 1994/08/21 18:44:04 ws Exp $ */ /*- * Copyright (C) 1994 Wolfgang Solfrank. * Copyright (C) 1994 TooLs GmbH. * All rights reserved. * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below). * * 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. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by TooLs GmbH. * 4. The name of TooLs GmbH may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``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 TOOLS GMBH 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. */ /* * Written by Paul Popelka (paulp@uts.amdahl.com) * * You can do anything you want with this software, just don't say you wrote * it, and don't remove this notice. * * This software is provided "as is". * * The author supplies this software to be publicly redistributed on the * understanding that the author is not responsible for the correct * functioning of this software in any circumstances and is not liable for * any damages caused by this software. * * October 1992 */ /* * kernel include files. */ #include #include #include #include #include #include /* to define statfs structure */ #include /* to define vattr structure */ #include /* * msdosfs include files. */ #include #include #include #include #include /* * Fat cache stats. */ int fc_fileextends; /* # of file extends */ int fc_lfcempty; /* # of time last file cluster cache entry * was empty */ int fc_bmapcalls; /* # of times pcbmap was called */ #define LMMAX 20 int fc_lmdistance[LMMAX]; /* counters for how far off the last * cluster mapped entry was. */ int fc_largedistance; /* off by more than LMMAX */ /* Byte offset in FAT on filesystem pmp, cluster cn */ #define FATOFS(pmp, cn) (FAT12(pmp) ? (cn) * 3 / 2 : (cn) * 2) static int chainalloc __P((struct msdosfsmount *pmp, u_long start, u_long count, u_long fillwith, u_long *retcluster, u_long *got)); static int chainlength __P((struct msdosfsmount *pmp, u_long start, u_long count)); static void fatblock __P((struct msdosfsmount *pmp, u_long ofs, u_long *bnp, u_long *sizep, u_long *bop)); static int fatchain __P((struct msdosfsmount *pmp, u_long start, u_long count, u_long fillwith)); static void fc_lookup __P((struct denode *dep, u_long findcn, u_long *frcnp, u_long *fsrcnp)); static void updatefats __P((struct msdosfsmount *pmp, struct buf *bp, u_long fatbn)); static void usemap_alloc __P((struct msdosfsmount *pmp, u_long cn)); static void usemap_free __P((struct msdosfsmount *pmp, u_long cn)); static void fatblock(pmp, ofs, bnp, sizep, bop) struct msdosfsmount *pmp; u_long ofs; u_long *bnp; u_long *sizep; u_long *bop; { u_long bn, size; bn = ofs / pmp->pm_fatblocksize * pmp->pm_fatblocksec; size = min(pmp->pm_fatblocksec, pmp->pm_FATsecs - bn) * pmp->pm_BytesPerSec; bn += pmp->pm_fatblk; if (bnp) *bnp = bn; if (sizep) *sizep = size; if (bop) *bop = ofs % pmp->pm_fatblocksize; } /* * Map the logical cluster number of a file into a physical disk sector * that is filesystem relative. * * dep - address of denode representing the file of interest * findcn - file relative cluster whose filesystem relative cluster number * and/or block number are/is to be found * bnp - address of where to place the file system relative block number. * If this pointer is null then don't return this quantity. * cnp - address of where to place the file system relative cluster number. * If this pointer is null then don't return this quantity. * * NOTE: Either bnp or cnp must be non-null. * This function has one side effect. If the requested file relative cluster * is beyond the end of file, then the actual number of clusters in the file * is returned in *cnp. This is useful for determining how long a directory is. * If cnp is null, nothing is returned. */ int pcbmap(dep, findcn, bnp, cnp) struct denode *dep; u_long findcn; /* file relative cluster to get */ daddr_t *bnp; /* returned filesys relative blk number */ u_long *cnp; /* returned cluster number */ { int error; u_long i; u_long cn; u_long prevcn; u_long byteoffset; u_long bn; u_long bo; struct buf *bp = NULL; u_long bp_bn = -1; struct msdosfsmount *pmp = dep->de_pmp; u_long bsize; int fat12 = FAT12(pmp); /* 12 bit fat */ fc_bmapcalls++; /* * If they don't give us someplace to return a value then don't * bother doing anything. */ if (bnp == NULL && cnp == NULL) return 0; cn = dep->de_StartCluster; /* * The "file" that makes up the root directory is contiguous, * permanently allocated, of fixed size, and is not made up of * clusters. If the cluster number is beyond the end of the root * directory, then return the number of clusters in the file. */ if (cn == MSDOSFSROOT) { if (dep->de_Attributes & ATTR_DIRECTORY) { if (findcn * pmp->pm_SectPerClust >= pmp->pm_rootdirsize) { if (cnp) *cnp = pmp->pm_rootdirsize / pmp->pm_SectPerClust; return E2BIG; } if (bnp) *bnp = pmp->pm_rootdirblk + (findcn * pmp->pm_SectPerClust); if (cnp) *cnp = MSDOSFSROOT; return 0; } else { /* just an empty file */ if (cnp) *cnp = 0; return E2BIG; } } /* * Rummage around in the fat cache, maybe we can avoid tromping * thru every fat entry for the file. And, keep track of how far * off the cache was from where we wanted to be. */ i = 0; fc_lookup(dep, findcn, &i, &cn); if ((bn = findcn - i) >= LMMAX) fc_largedistance++; else fc_lmdistance[bn]++; /* * Handle all other files or directories the normal way. */ prevcn = 0; for (; i < findcn; i++) { if (MSDOSFSEOF(cn)) goto hiteof; byteoffset = FATOFS(pmp, cn); fatblock(pmp, byteoffset, &bn, &bsize, &bo); if (bn != bp_bn) { if (bp) brelse(bp); error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); if (error) return error; bp_bn = bn; } prevcn = cn; cn = getushort(&bp->b_data[bo]); if (fat12) { if (prevcn & 1) cn >>= 4; cn &= 0x0fff; /* * Force the special cluster numbers in the range * 0x0ff0-0x0fff to be the same as for 16 bit * cluster numbers to let the rest of msdosfs think * it is always dealing with 16 bit fats. */ if ((cn & 0x0ff0) == 0x0ff0) cn |= 0xf000; } } if (!MSDOSFSEOF(cn)) { if (bp) brelse(bp); if (bnp) *bnp = cntobn(pmp, cn); if (cnp) *cnp = cn; fc_setcache(dep, FC_LASTMAP, i, cn); return 0; } hiteof:; if (cnp) *cnp = i; if (bp) brelse(bp); /* update last file cluster entry in the fat cache */ fc_setcache(dep, FC_LASTFC, i - 1, prevcn); return E2BIG; } /* * Find the closest entry in the fat cache to the cluster we are looking * for. */ static void fc_lookup(dep, findcn, frcnp, fsrcnp) struct denode *dep; u_long findcn; u_long *frcnp; u_long *fsrcnp; { int i; u_long cn; struct fatcache *closest = 0; for (i = 0; i < FC_SIZE; i++) { cn = dep->de_fc[i].fc_frcn; if (cn != FCE_EMPTY && cn <= findcn) { if (closest == 0 || cn > closest->fc_frcn) closest = &dep->de_fc[i]; } } if (closest) { *frcnp = closest->fc_frcn; *fsrcnp = closest->fc_fsrcn; } } /* * Purge the fat cache in denode dep of all entries relating to file * relative cluster frcn and beyond. */ void fc_purge(dep, frcn) struct denode *dep; u_int frcn; { int i; struct fatcache *fcp; fcp = dep->de_fc; for (i = 0; i < FC_SIZE; i++, fcp++) { if (fcp->fc_frcn >= frcn) fcp->fc_frcn = FCE_EMPTY; } } /* * Update all copies of the fat. The first copy is updated last. * * pmp - msdosfsmount structure for filesystem to update * bp - addr of modified fat block * fatbn - block number relative to begin of filesystem of the modified fat block. */ static void updatefats(pmp, bp, fatbn) struct msdosfsmount *pmp; struct buf *bp; u_long fatbn; { int i; struct buf *bpn; #ifdef MSDOSFS_DEBUG printf("updatefats(pmp %p, bp %p, fatbn %ld)\n", pmp, bp, fatbn); #endif /* * Now copy the block(s) of the modified fat to the other copies of * the fat and write them out. This is faster than reading in the * other fats and then writing them back out. This could tie up * the fat for quite a while. Preventing others from accessing it. * To prevent us from going after the fat quite so much we use * delayed writes, unless they specfied "synchronous" when the * filesystem was mounted. If synch is asked for then use * bwrite()'s and really slow things down. */ for (i = 1; i < pmp->pm_FATs; i++) { fatbn += pmp->pm_FATsecs; /* getblk() never fails */ bpn = getblk(pmp->pm_devvp, fatbn, bp->b_bcount, 0, 0); bcopy(bp->b_data, bpn->b_data, bp->b_bcount); if (pmp->pm_waitonfat) bwrite(bpn); else bdwrite(bpn); } /* * Write out the first fat last. */ if (pmp->pm_waitonfat) bwrite(bp); else bdwrite(bp); } /* * Updating entries in 12 bit fats is a pain in the butt. * * The following picture shows where nibbles go when moving from a 12 bit * cluster number into the appropriate bytes in the FAT. * * byte m byte m+1 byte m+2 * +----+----+ +----+----+ +----+----+ * | 0 1 | | 2 3 | | 4 5 | FAT bytes * +----+----+ +----+----+ +----+----+ * * +----+----+----+ +----+----+----+ * | 3 0 1 | | 4 5 2 | * +----+----+----+ +----+----+----+ * cluster n cluster n+1 * * Where n is even. m = n + (n >> 2) * */ static inline void usemap_alloc(pmp, cn) struct msdosfsmount *pmp; u_long cn; { pmp->pm_inusemap[cn / N_INUSEBITS] |= 1 << (cn % N_INUSEBITS); pmp->pm_freeclustercount--; } static inline void usemap_free(pmp, cn) struct msdosfsmount *pmp; u_long cn; { pmp->pm_freeclustercount++; pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1 << (cn % N_INUSEBITS)); } int clusterfree(pmp, cluster, oldcnp) struct msdosfsmount *pmp; u_long cluster; u_long *oldcnp; { int error; u_long oldcn; error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE); if (error == 0) { /* * If the cluster was successfully marked free, then update * the count of free clusters, and turn off the "allocated" * bit in the "in use" cluster bit map. */ usemap_free(pmp, cluster); if (oldcnp) *oldcnp = oldcn; } return error; } /* * Get or Set or 'Get and Set' the cluster'th entry in the fat. * * function - whether to get or set a fat entry * pmp - address of the msdosfsmount structure for the filesystem * whose fat is to be manipulated. * cn - which cluster is of interest * oldcontents - address of a word that is to receive the contents of the * cluster'th entry if this is a get function * newcontents - the new value to be written into the cluster'th element of * the fat if this is a set function. * * This function can also be used to free a cluster by setting the fat entry * for a cluster to 0. * * All copies of the fat are updated if this is a set function. NOTE: If * fatentry() marks a cluster as free it does not update the inusemap in * the msdosfsmount structure. This is left to the caller. */ int fatentry(function, pmp, cn, oldcontents, newcontents) int function; struct msdosfsmount *pmp; u_long cn; u_long *oldcontents; u_long newcontents; { int error; u_long readcn; u_long bn, bo, bsize, byteoffset; struct buf *bp; /* * printf("fatentry(func %d, pmp %08x, clust %d, oldcon %08x, newcon %d)\n", * function, pmp, cluster, oldcontents, newcontents); */ #ifdef DIAGNOSTIC /* * Be sure they asked us to do something. */ if ((function & (FAT_SET | FAT_GET)) == 0) { printf("fatentry(): function code doesn't specify get or set\n"); return EINVAL; } /* * If they asked us to return a cluster number but didn't tell us * where to put it, give them an error. */ if ((function & FAT_GET) && oldcontents == NULL) { printf("fatentry(): get function with no place to put result\n"); return EINVAL; } #endif /* * Be sure the requested cluster is in the filesystem. */ if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster) return EINVAL; byteoffset = FATOFS(pmp, cn); fatblock(pmp, byteoffset, &bn, &bsize, &bo); error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); if (error) return error; if (function & FAT_GET) { readcn = getushort(&bp->b_data[bo]); if (FAT12(pmp)) { if (cn & 1) readcn >>= 4; readcn &= 0x0fff; /* map certain 12 bit fat entries to 16 bit */ if ((readcn & 0x0ff0) == 0x0ff0) readcn |= 0xf000; } *oldcontents = readcn; } if (function & FAT_SET) { if (FAT12(pmp)) { readcn = getushort(&bp->b_data[bo]); if (cn & 1) { readcn &= 0x000f; readcn |= newcontents << 4; } else { readcn &= 0xf000; readcn |= newcontents & 0xfff; } putushort(&bp->b_data[bo], readcn); } else putushort(&bp->b_data[bo], newcontents); updatefats(pmp, bp, bn); bp = NULL; pmp->pm_fmod = 1; } if (bp) brelse(bp); return 0; } /* * Update a contiguous cluster chain * * pmp - mount point * start - first cluster of chain * count - number of clusters in chain * fillwith - what to write into fat entry of last cluster */ static int fatchain(pmp, start, count, fillwith) struct msdosfsmount *pmp; u_long start; u_long count; u_long fillwith; { int error; u_long bn, bo, bsize, byteoffset, readcn, newc; struct buf *bp; #ifdef MSDOSFS_DEBUG printf("fatchain(pmp %p, start %ld, count %ld, fillwith %ld)\n", pmp, start, count, fillwith); #endif /* * Be sure the clusters are in the filesystem. */ if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster) return EINVAL; while (count > 0) { byteoffset = FATOFS(pmp, start); fatblock(pmp, byteoffset, &bn, &bsize, &bo); error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); if (error) return error; while (count > 0) { start++; newc = --count > 0 ? start : fillwith; if (FAT12(pmp)) { readcn = getushort(&bp->b_data[bo]); if (start & 1) { readcn &= 0xf000; readcn |= newc & 0xfff; } else { readcn &= 0x000f; readcn |= newc << 4; } putushort(&bp->b_data[bo], readcn); bo++; if (!(start & 1)) bo++; } else { putushort(&bp->b_data[bo], newc); bo += 2; } if (bo >= bsize) break; } updatefats(pmp, bp, bn); } pmp->pm_fmod = 1; return 0; } /* * Check the length of a free cluster chain starting at start. * * pmp - mount point * start - start of chain * count - maximum interesting length */ static int chainlength(pmp, start, count) struct msdosfsmount *pmp; u_long start; u_long count; { u_long idx, max_idx; u_int map; u_long len; max_idx = pmp->pm_maxcluster / N_INUSEBITS; idx = start / N_INUSEBITS; start %= N_INUSEBITS; map = pmp->pm_inusemap[idx]; map &= ~((1 << start) - 1); if (map) { len = ffs(map) - 1 - start; return len > count ? count : len; } len = N_INUSEBITS - start; if (len >= count) return count; while (++idx <= max_idx) { if (len >= count) break; map = pmp->pm_inusemap[idx]; if (map) { len += ffs(map) - 1; break; } len += N_INUSEBITS; } return len > count ? count : len; } /* * Allocate contigous free clusters. * * pmp - mount point. * start - start of cluster chain. * count - number of clusters to allocate. * fillwith - put this value into the fat entry for the * last allocated cluster. * retcluster - put the first allocated cluster's number here. * got - how many clusters were actually allocated. */ static int chainalloc(pmp, start, count, fillwith, retcluster, got) struct msdosfsmount *pmp; u_long start; u_long count; u_long fillwith; u_long *retcluster; u_long *got; { int error; error = fatchain(pmp, start, count, fillwith); if (error == 0) { #ifdef MSDOSFS_DEBUG printf("clusteralloc(): allocated cluster chain at %ld (%ld clusters)\n", start, count); #endif if (retcluster) *retcluster = start; if (got) *got = count; while (count-- > 0) usemap_alloc(pmp, start++); } return error; } /* * Allocate contiguous free clusters. * * pmp - mount point. * start - preferred start of cluster chain. * count - number of clusters requested. * fillwith - put this value into the fat entry for the * last allocated cluster. * retcluster - put the first allocated cluster's number here. * got - how many clusters were actually allocated. */ int clusteralloc(pmp, start, count, fillwith, retcluster, got) struct msdosfsmount *pmp; u_long start; u_long count; u_long fillwith; u_long *retcluster; u_long *got; { u_long idx; u_long len, newst, foundcn, foundl, cn, l; u_int map; #ifdef MSDOSFS_DEBUG printf("clusteralloc(): find %d clusters\n",count); #endif if (start) { if ((len = chainlength(pmp, start, count)) >= count) return chainalloc(pmp, start, count, fillwith, retcluster, got); } else { /* * This is a new file, initialize start */ struct timeval tv; microtime(&tv); start = (tv.tv_usec >> 10)|tv.tv_usec; len = 0; } /* * Start at a (pseudo) random place to maximize cluster runs * under multiple writers. */ foundcn = newst = (start * 1103515245 + 12345) % (pmp->pm_maxcluster + 1); foundl = 0; for (cn = newst; cn <= pmp->pm_maxcluster;) { idx = cn / N_INUSEBITS; map = pmp->pm_inusemap[idx]; map |= (1 << (cn % N_INUSEBITS)) - 1; if (map != (u_int)-1) { cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1; if ((l = chainlength(pmp, cn, count)) >= count) return chainalloc(pmp, cn, count, fillwith, retcluster, got); if (l > foundl) { foundcn = cn; foundl = l; } cn += l + 1; continue; } cn += N_INUSEBITS - cn % N_INUSEBITS; } for (cn = 0; cn < newst;) { idx = cn / N_INUSEBITS; map = pmp->pm_inusemap[idx]; map |= (1 << (cn % N_INUSEBITS)) - 1; if (map != (u_int)-1) { cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1; if ((l = chainlength(pmp, cn, count)) >= count) return chainalloc(pmp, cn, count, fillwith, retcluster, got); if (l > foundl) { foundcn = cn; foundl = l; } cn += l + 1; continue; } cn += N_INUSEBITS - cn % N_INUSEBITS; } if (!foundl) return ENOSPC; if (len) return chainalloc(pmp, start, len, fillwith, retcluster, got); else return chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got); } /* * Free a chain of clusters. * * pmp - address of the msdosfs mount structure for the filesystem * containing the cluster chain to be freed. * startcluster - number of the 1st cluster in the chain of clusters to be * freed. */ int freeclusterchain(pmp, cluster) struct msdosfsmount *pmp; u_long cluster; { int error = 0; struct buf *bp = NULL; u_long bn, bo, bsize, byteoffset; u_long readcn, lbn = -1; while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) { byteoffset = FATOFS(pmp, cluster); fatblock(pmp, byteoffset, &bn, &bsize, &bo); if (lbn != bn) { if (bp) updatefats(pmp, bp, lbn); error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); if (error) return error; lbn = bn; } usemap_free(pmp, cluster); readcn = getushort(&bp->b_data[bo]); if (FAT12(pmp)) { if (cluster & 1) { cluster = readcn >> 4; readcn &= 0x000f; readcn |= MSDOSFSFREE << 4; } else { cluster = readcn; readcn &= 0xf000; readcn |= MSDOSFSFREE & 0xfff; } putushort(&bp->b_data[bo], readcn); cluster &= 0x0fff; if ((cluster&0x0ff0) == 0x0ff0) cluster |= 0xf000; } else { cluster = readcn; putushort(&bp->b_data[bo], MSDOSFSFREE); } } if (bp) updatefats(pmp, bp, bn); return error; } /* * Read in fat blocks looking for free clusters. For every free cluster * found turn off its corresponding bit in the pm_inusemap. */ int fillinusemap(pmp) struct msdosfsmount *pmp; { struct buf *bp = NULL; u_long cn, readcn; int error; int fat12 = FAT12(pmp); u_long bn, bo, bsize, byteoffset; /* * Mark all clusters in use, we mark the free ones in the fat scan * loop further down. */ for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++) pmp->pm_inusemap[cn] = (u_int)-1; /* * Figure how many free clusters are in the filesystem by ripping * through the fat counting the number of entries whose content is * zero. These represent free clusters. */ pmp->pm_freeclustercount = 0; for (cn = CLUST_FIRST; cn <= pmp->pm_maxcluster; cn++) { byteoffset = FATOFS(pmp, cn); bo = byteoffset % pmp->pm_fatblocksize; if (!bo || !bp) { /* Read new FAT block */ if (bp) brelse(bp); fatblock(pmp, byteoffset, &bn, &bsize, NULL); error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); if (error) return error; } readcn = getushort(&bp->b_data[bo]); if (fat12) { if (cn & 1) readcn >>= 4; readcn &= 0x0fff; } if (readcn == 0) usemap_free(pmp, cn); } brelse(bp); return 0; } /* * Allocate a new cluster and chain it onto the end of the file. * * dep - the file to extend * count - number of clusters to allocate * bpp - where to return the address of the buf header for the first new * file block * ncp - where to put cluster number of the first newly allocated cluster * If this pointer is 0, do not return the cluster number. * flags - see fat.h * * NOTE: This function is not responsible for turning on the DE_UPDATE bit of * the de_flag field of the denode and it does not change the de_FileSize * field. This is left for the caller to do. */ int extendfile(dep, count, bpp, ncp, flags) struct denode *dep; u_long count; struct buf **bpp; u_long *ncp; int flags; { int error = 0; u_long frcn; u_long cn, got; struct msdosfsmount *pmp = dep->de_pmp; struct buf *bp; /* * Don't try to extend the root directory */ if (DETOV(dep)->v_flag & VROOT) { printf("extendfile(): attempt to extend root directory\n"); return ENOSPC; } /* * If the "file's last cluster" cache entry is empty, and the file * is not empty, then fill the cache entry by calling pcbmap(). */ fc_fileextends++; if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY && dep->de_StartCluster != 0) { fc_lfcempty++; error = pcbmap(dep, 0xffff, 0, &cn); /* we expect it to return E2BIG */ if (error != E2BIG) return error; error = 0; } while (count > 0) { /* * Allocate a new cluster chain and cat onto the end of the file. * If the file is empty we make de_StartCluster point to the new * block. Note that de_StartCluster being 0 is sufficient to be * sure the file is empty since we exclude attempts to extend the * root directory above, and the root dir is the only file with a * startcluster of 0 that has blocks allocated (sort of). */ if (dep->de_StartCluster == 0) cn = 0; else cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1; error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got); if (error) return error; count -= got; /* * Give them the filesystem relative cluster number if they want * it. */ if (ncp) { *ncp = cn; ncp = NULL; } if (dep->de_StartCluster == 0) { dep->de_StartCluster = cn; frcn = 0; } else { error = fatentry(FAT_SET, pmp, dep->de_fc[FC_LASTFC].fc_fsrcn, 0, cn); if (error) { clusterfree(pmp, cn, NULL); return error; } frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1; } /* * Update the "last cluster of the file" entry in the denode's fat * cache. */ fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1); if (flags & DE_CLEAR) { while (got-- > 0) { /* * Get the buf header for the new block of the file. */ if (dep->de_Attributes & ATTR_DIRECTORY) bp = getblk(pmp->pm_devvp, cntobn(pmp, cn++), pmp->pm_bpcluster, 0, 0); else { bp = getblk(DETOV(dep), frcn++, pmp->pm_bpcluster, 0, 0); /* * Do the bmap now, as in msdosfs_write */ if (pcbmap(dep, bp->b_lblkno, &bp->b_blkno, 0)) bp->b_blkno = -1; if (bp->b_blkno == -1) panic("extendfile: pcbmap"); } clrbuf(bp); if (bpp) { *bpp = bp; bpp = NULL; } else { bp->b_flags |= B_AGE; bawrite(bp); } } } } return 0; }