ref: c8b187f9db503465460d8bafa2d7a758bbcf59ca
dir: /liblogfs/read.c/
#include "logfsos.h" #include "logfs.h" #include "local.h" #include "fcall.h" struct DirReadState { u32 offset; u32 lastoffset; u32 limit; uchar *data; }; typedef struct ReaderState { uchar *buf; u32 maxoffset; LogfsServer *server; char *errmsg; } ReaderState; static DirReadState * drsinit(LogfsIdentityStore *is, Entry *list, uchar *buf, u32 buflen, u32 *rcount) { Entry *p, *q; DirReadState *drs; u32 k; /* * stash as many entries as will fit in the read buffer */ *rcount = 0; for(p = list; p; p = p->next) { uint len = logfsflattenentry(is, buf, buflen, p); if(len == 0) break; *rcount += len; buf += len; buflen -= len; } drs = logfsrealloc(nil, sizeof(*drs)); if(drs == nil) return nil; drs->offset = *rcount; drs->lastoffset = drs->offset; k = 0; for(q = p; q; q = q->next) k += logfsflattenentry(is, nil, 0, q); if(k) { u32 k2; // print("drsinit: %ud bytes extra\n", k); drs->data = logfsrealloc(nil, k); if(drs->data == nil) { logfsfreemem(drs); return nil; } k2 = 0; for(q = p; q; q = q->next) k2 += logfsflattenentry(is, drs->data + k2, k - k2, q); drs->limit = drs->offset + k; } // print("drsinit: rcount %ud\n", *rcount); return drs; } static void drsread(DirReadState *drs, uchar *buf, u32 buflen, u32 *rcount) { uchar *p; *rcount = 0; p = drs->data + drs->lastoffset - drs->offset; while(drs->lastoffset < drs->limit) { /* * copy an entry, if it fits */ uint len = GBIT16(p) + BIT16SZ; if(len > buflen) break; memmove(buf, p, len); drs->lastoffset += len; *rcount += len; buf += len; buflen -= len; p += len; } if(drs->lastoffset >= drs->limit) { logfsfreemem(drs->data); drs->data = nil; } } void logfsdrsfree(DirReadState **drsp) { DirReadState *drs = *drsp; if(drs) { logfsfreemem(drs->data); logfsfreemem(drs); *drsp = nil; } } static int reader(void *magic, u32 baseoffset, u32 limitoffset, Extent *e, u32 extentoffset) { ReaderState *s = magic; LogfsServer *server; LogfsLowLevel *ll; LogfsLowLevelReadResult llrr; long seq; int page; int offset; long block; int pagesize; LogSegment *seg; int replace; if(e == nil) { //print("fill(%d, %d)\n", baseoffset, limitoffset); memset(s->buf + baseoffset, 0, limitoffset - baseoffset); if(limitoffset > s->maxoffset) s->maxoffset = limitoffset; return 1; } server = s->server; ll = server->ll; /* * extentoffset is how much to trim off the front of the extent */ logfsflashaddr2spo(server, e->flashaddr + extentoffset, &seq, &page, &offset); /* * offset is the offset within the page to where e->min is stored */ //print("read(%d, %d, %c%ld/%ud/%ud)\n", // baseoffset, limitoffset, (e->flashaddr & LogAddr) ? 'L' : 'D', seq, page, offset); if(e->flashaddr & LogAddr) { if(seq >= server->activelog->unsweptblockindex && seq <= server->activelog->curblockindex) seg = server->activelog; else if(server->sweptlog && seq <= server->sweptlog->curblockindex) seg = server->sweptlog; else { print("logfsserverread: illegal log sequence number %ld (active=[%ld, %ld], swept=[%ld, %ld])\n", seq, server->activelog->unsweptblockindex, server->activelog->curblockindex, server->sweptlog ? 0L : -1L, server->sweptlog ? server->sweptlog->curblockindex : -1L); s->errmsg = logfseinternal; return -1; } if(seg->curpage == page && seg->curblockindex == seq) { /* * it hasn't made it to disk yet */ memmove(s->buf + baseoffset, seg->pagebuf + offset, limitoffset - baseoffset); goto done; } if(seq < seg->unsweptblockindex) { /* data already swept */ print("logfsserverread: log address has been swept\n"); s->errmsg = logfseinternal; return -1; } block = seg->blockmap[seq]; } else { seg = nil; if(seq >= server->ndatablocks) block = -1; else block = server->datablock[seq].block; if(block < 0) { print("logfsserveread: data address does not exist\n"); s->errmsg = logfseinternal; return -1; } } /* * read as many pages as necessary to get to the limitoffset */ pagesize = 1 << ll->l2pagesize; replace = 0; while(baseoffset < limitoffset) { u32 thistime; thistime = pagesize - offset; if(thistime > (limitoffset - baseoffset)) thistime = limitoffset - baseoffset; s->errmsg = (*ll->readpagerange)(ll, s->buf + baseoffset, block, page, offset, thistime, &llrr); if(s->errmsg) return -1; if(llrr != LogfsLowLevelReadResultOk) { replace = 1; } baseoffset += thistime; page++; offset = 0; } if(replace) { s->errmsg = logfsserverreplaceblock(server, seg, seq); if(s->errmsg) return -1; } done: if(limitoffset > s->maxoffset) s->maxoffset = limitoffset; return 1; } char * logfsserverread(LogfsServer *server, u32 fid, u32 offset, u32 count, uchar *buf, u32 buflen, u32 *rcount) { Fid *f; Entry *e; ReaderState s; int rv; if(server->trace > 1) print("logfsserverread(%ud, %ud, %ud)\n", fid, offset, count); f = logfsfidmapfindentry(server->fidmap, fid); if(f == nil) return logfsebadfid; if(f->openmode < 0) return logfsefidnotopen; if((f->openmode & 3) == OWRITE) return logfseaccess; if(count > buflen) return Etoobig; e = f->entry; if(e->deadandgone) return Eio; if(e->qid.type & QTDIR) { if(offset != 0) { if(f->drs == nil || f->drs->lastoffset != offset) return Eio; drsread(f->drs, buf, count, rcount); } else { logfsdrsfree(&f->drs); f->drs = drsinit(server->is, e->u.dir.list, buf, count, rcount); if(f->drs == nil) return Enomem; } return nil; } if(offset >= e->u.file.length) { *rcount = 0; return nil; } s.buf = buf; s.server = server; s.maxoffset = 0; rv = logfsextentlistwalkrange(e->u.file.extent, reader, &s, offset, offset + count); if(rv < 0) return s.errmsg; *rcount = s.maxoffset; return nil; }