ref: c8b187f9db503465460d8bafa2d7a758bbcf59ca
dir: /liblogfs/write.c/
#include "logfsos.h" #include "logfs.h" #include "local.h" typedef struct AllocState AllocState; struct AllocState { long oldblock; int markbad; }; Pageset logfsdatapagemask(int pages, int base) { if(pages == BITSPERSET) return ~(Pageset)0; return (((Pageset)1 << pages) - 1) << (BITSPERSET - base - pages); } static Pageset fastgap(Pageset w, uint n) { Pageset s; //print("fastgap(0x%.8ux, %d)\n", w, n); if(w == 0 || n < 1 || n > BITSPERSET) return 0; /* # unroll the following loop 5 times: # while(n > 1){ # s := n >> 1; # w &= w<<s; # n -= s; # } */ s = n >> 1; w &= w << s; n -= s; s = n >> 1; w &= w << s; n -= s; s = n >> 1; w &= w << s; n -= s; s = n >> 1; w &= w << s; n -= s; s = n >> 1; if(BITSPERSET == 64){ /* extra time if 64 bits */ w &= w << s; n -= s; s = n >> 1; } return w & (w << s); } static int nlz(Pageset x) { int n, c; if(x == 0) return BITSPERSET; if(x & PAGETOP) return 0; n = BITSPERSET; c = BITSPERSET/2; do { Pageset y; y = x >> c; if(y != 0) { n -= c; x = y; } } while((c >>= 1) != 0); return n - x; } static Pageset findgap(Pageset w, uint n) { Pageset m; do { m = fastgap(w, n); if(m) break; n--; } while(n); if(n == 0) return 0; return logfsdatapagemask(n, nlz(m)); } static int bitcount(Pageset mask) { Pageset m; int rv; rv = 0; for(m = PAGETOP; m != 0; m >>= 1) if(mask & m) rv++; return rv; } static char * allocdatapages(LogfsServer *server, u32 count, int *countp, long *blockindexp, int *pagep, u32 *flashaddr, AllocState *state) { LogfsLowLevel *ll = server->ll; long b, blockindex; DataBlock *db; int pagebase; u32 pages = (count + (1 << ll->l2pagesize) - 1) >> ll->l2pagesize; u32 gapmask; long bestfreeblockindex; int bestfree; int pagesperblock = 1 << ll->l2pagesperblock; int apages; char *errmsg; int didsomething; state->oldblock = -1; state->markbad = 0; if(pages > pagesperblock) pages = pagesperblock; /* * fill in gaps first */ bestfreeblockindex = -1; bestfree = 0; for(blockindex = 0; blockindex < server->ndatablocks; blockindex++) { db = server->datablock + blockindex; if(db->block < 0) continue; gapmask = findgap(db->free & ~db->dirty, pages); //print("blockindex %ld free 0x%.8ux dirty 0x%.8ux gapmask %.8ux\n", blockindex, db->free, db->dirty, gapmask); if(gapmask != 0) { /* * this is free and !dirty */ b = db->block; USED(b); goto done; } else { int free = bitcount(db->free & logfsdatapagemask(pagesperblock, 0)); if(free > 0 && (bestfreeblockindex < 0 || free > bestfree)) { bestfreeblockindex = blockindex; bestfree = free; } } } //print("out of space - need to clean up a data block\n"); if(bestfreeblockindex >= 0) { //print("best block index %ld (%ld) %d bits\n", bestfreeblockindex, server->datablock[bestfreeblockindex].block, bestfree); /* * clean up data block */ b = logfsfindfreeblock(ll, AllocReasonTransfer); while(b >= 0) { char *errmsg; LogfsLowLevelReadResult llrr; long oldblock; int markedbad; db = server->datablock + bestfreeblockindex; oldblock = db->block; errmsg = logfsservercopyactivedata(server, b, bestfreeblockindex, 0, &llrr, &markedbad); if(errmsg) { if(!markedbad) return errmsg; b = logfsfindfreeblock(ll, AllocReasonTransfer); } else { Pageset available; /* * if page0 is free, then we must ensure that we use it otherwise * in tagged storage such as nand, the block tag is not written * in all cases, it is safer to erase the block afterwards to * preserve the data for as long as possible (we could choose * to erase the old block now if page0 has already been copied) */ blockindex = bestfreeblockindex; state->oldblock = oldblock; state->markbad = llrr != LogfsLowLevelReadResultOk; available = db->free & ~db->dirty; if(available & PAGETOP) available = logfsdatapagemask(nlz(~available), 0); gapmask = findgap(available, pages); goto done; } } } /* * use already erased blocks, so long as there are a few free */ b = logfsfindfreeblock(ll, AllocReasonDataExtend); if(b >= 0) { useerased: for(blockindex = 0, db = server->datablock; blockindex < server->ndatablocks; blockindex++, db++) if(db->block < 0) break; if(blockindex == server->ndatablocks) server->ndatablocks++; db->path = mkdatapath(blockindex, 0); db->block = b; (*ll->setblocktag)(ll, b, LogfsTdata); (*ll->setblockpath)(ll, b, db->path); db->free = logfsdatapagemask(pagesperblock, 0); db->dirty = 0; gapmask = db->free; goto done; } /* * last resort; try to steal from log */ //print("last resort\n"); errmsg = logfsserverlogsweep(server, 0, &didsomething); if(errmsg) return errmsg; if(didsomething) { /* * this can only create whole free blocks, so... */ //print("findfree after last resort\n"); b = logfsfindfreeblock(ll, AllocReasonDataExtend); if(b >= 0) { //print("*********************************************************\n"); goto useerased; } } *countp = 0; return nil; done: /* * common finish - needs gapmask, blockindex, db */ apages = bitcount(gapmask); pagebase = nlz(gapmask); if(apages > pages) apages = pages; gapmask = logfsdatapagemask(apages, pagebase); if(server->trace > 1) print("allocdatapages: block %ld(%ld) pages %d mask 0x%.8ux pagebase %d apages %d\n", blockindex, db->block, pages, gapmask, pagebase, apages); db->free &= ~gapmask; db->dirty |= gapmask; *pagep = pagebase; *blockindexp = blockindex; *flashaddr = logfsspo2flashaddr(server, blockindex, pagebase, 0); *countp = apages << ll->l2pagesize; if(*countp > count) *countp = count; return nil; } typedef struct Page { u32 pageaddr; int ref; } Page; typedef struct DataStructure { LogfsServer *server; int nentries; int maxentries; Page *array; } DataStructure; static int deltapage(DataStructure *ds, u32 pageaddr, int add, int delta) { int i; for(i = 0; i < ds->nentries; i++) if(ds->array[i].pageaddr == pageaddr) { ds->array[i].ref += delta; return 1; } if(!add) return 1; if(ds->maxentries == 0) { ds->array = logfsrealloc(nil, sizeof(Page) * 100); if(ds->array == nil) return 0; ds->maxentries = 100; } else if(ds->nentries >= ds->maxentries) { void *a = logfsrealloc(ds->array, ds->maxentries * 2 * sizeof(Page)); if(a == nil) return 0; ds->array = a; ds->maxentries *= 2; } ds->array[ds->nentries].pageaddr = pageaddr; ds->array[ds->nentries++].ref = delta; return 1; } /* * only called for data addresses */ static int deltapages(DataStructure *ds, LogfsLowLevel *ll, u32 baseflashaddr, int range, int add, int delta) { long seq; int page, offset; int pages; u32 pageaddr; int x; //print("deltapages(%ud, %ud, %d, %d)\n", baseflashaddr, limitflashaddr, add, delta); logfsflashaddr2spo(ds->server, baseflashaddr, &seq, &page, &offset); pages = (offset + range + (1 << ll->l2pagesize) - 1) >> ll->l2pagesize; pageaddr = (seq << ll->l2pagesperblock) + page; for(x = 0; x < pages; x++, pageaddr++) if(!deltapage(ds, pageaddr, add, delta)) return 0; return 1; } static int findpageset(void *magic, u32 baseoffset, u32 limitoffset, Extent *e, u32 extentoffset) { DataStructure *ds = magic; LogfsLowLevel *ll; u32 flashaddr; u32 range; u32 residue; if(e == nil || (e->flashaddr & LogAddr) != 0) return 1; ll = ds->server->ll; //print("baseoffset %ud limitoffset %ud min %ud max %ud\n", baseoffset, limitoffset, e->min, e->max); flashaddr = e->flashaddr; if(extentoffset) if(!deltapages(ds, ll, flashaddr, extentoffset, 1, 1)) return -1; flashaddr += extentoffset; range = limitoffset - baseoffset; if(!deltapages(ds, ll, flashaddr, range, 1, -1)) return -1; flashaddr += range; residue = e->max - e->min - (extentoffset + range); if(residue) if(!deltapages(ds, ll, flashaddr, residue, 1, 1)) return -1; return 1; } static int addpagereferences(void *magic, Extent *e, int hole) { DataStructure *ds = magic; if(hole || (e->flashaddr & LogAddr) != 0) return 1; return deltapages(ds, ds->server->ll, e->flashaddr, e->max - e->min, 0, 1) ? 1 : -1; } static char * zappages(LogfsServer *server, Entry *e, u32 min, u32 max) { DataStructure ds; long seq; int x, rv, page; Page *p; if(min >= e->u.file.length) return nil; /* no checks necessary */ if(min == 0 && max >= e->u.file.length) { /* replacing entire file */ logfsextentlistwalk(e->u.file.extent, logfsunconditionallymarkfreeanddirty, server); return nil; } /* hard after that - this will need to be improved */ /* * current algorithm * build a list of all pages referenced by the extents being removed, and count the * number of references * then subtract the number of references to each page in entire file * any pages with a reference count == 0 can be removed */ ds.server = server; ds.nentries = 0; ds.maxentries = 0; ds.array = nil; rv = logfsextentlistwalkrange(e->u.file.extent, findpageset, &ds, min, max); if(rv < 0 || ds.nentries == 0) goto Out; if(server->trace > 1){ print("pass 1\n"); for(x = 0; x < ds.nentries; x++){ p = &ds.array[x]; seq = p->pageaddr >> server->ll->l2pagesperblock; page = p->pageaddr & ((1 << server->ll->l2pagesperblock) - 1); print("block %lud page %ud ref %d\n", seq, page, p->ref); } print("pass 2\n"); } rv = logfsextentlistwalk(e->u.file.extent, addpagereferences, &ds); if(rv >= 0){ for(x = 0; x < ds.nentries; x++){ p = &ds.array[x]; seq = p->pageaddr >> server->ll->l2pagesperblock; page = p->pageaddr & ((1 << server->ll->l2pagesperblock) - 1); if(server->trace > 1) print("block %lud page %ud ref %d\n", seq, page, p->ref); if(p->ref == 0) logfsfreedatapages(server, seq, logfsdatapagemask(1, page)); } } Out: logfsfreemem(ds.array); return rv < 0 ? Enomem : nil; } static void disposeofoldblock(LogfsServer *server, AllocState *state) { if(state->oldblock >= 0) { if(server->testflags & LogfsTestDontFettleDataBlock) { /* take the block out of commission */ (*server->ll->setblocktag)(server->ll, state->oldblock, LogfsTworse); server->testflags &= ~LogfsTestDontFettleDataBlock; } else { if(state->markbad) (*server->ll->markblockbad)(server->ll, state->oldblock); else logfsbootfettleblock(server->lb, state->oldblock, LogfsTnone, ~0, nil); } state->oldblock = -1; } } char * logfsserverwrite(LogfsServer *server, u32 fid, u32 offset, u32 count, uchar *buf, u32 *rcount) { Fid *f; Entry *e; u32 now; char *muid; int muidlen; LogfsLowLevel *ll = server->ll; if(server->trace > 1) print("logfsserverwrite(%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) == OREAD) return logfseaccess; e = f->entry; if(e->deadandgone) return Eio; if(e->qid.type & QTDIR) return Eperm; if(e->perm & DMAPPEND) offset = e->u.file.length; now = logfsnow(); *rcount = count; muid = logfsisfindidfromname(server->is, f->uname); muidlen = strlen(muid); while(count) { Extent extent; int thistime; char *errmsg; thistime = lognicesizeforwrite(server, 1, count, muidlen); if(thistime == 0) { int p; u32 n; long blockindex; int pagebase; AllocState state; int pagesize = 1 << ll->l2pagesize; reallocate: errmsg = allocdatapages(server, count, &thistime, &blockindex, &pagebase, &extent.flashaddr, &state); if(errmsg) return errmsg; if(thistime == 0) return logfselogfull; for(p = pagebase, n = 0; n < thistime; p++, n += pagesize) { u32 mask; DataBlock *db = server->datablock + blockindex; errmsg = (*ll->writepage)(ll, buf + n, db->block, p); if(errmsg) { if(strcmp(errmsg, Eio) != 0) { /* * something horrid happened down below * recover without writing any more than we have to */ if(p != 0) { /* * page 0 was either written already, or has been written in this loop * thus the block referenced is valid on the media. all we need to do * is lose the old block, mark the written pages as free (so they can * be scavenged), and don't bother with the log message */ disposeofoldblock(server, &state); mask = logfsdatapagemask(p - pagebase - 1, pagebase); db->free |= mask; db->dirty |= mask; return errmsg; } /* * page 0 failed to write (so nothing written at all) * this is either an entirely free block (no erased block in savestate), * or a copy of a scavenged block (erased block in savestate) */ if(state.oldblock < 0) { /* * newly selected erased block (blockindex == server->ndatablocks - 1) * mark it bad, lose it from the datablock table */ (*ll->markblockbad)(ll, db->block); db->block = -1; if(blockindex == server->ndatablocks - 1) server->ndatablocks--; return errmsg; } /* * page 0 of a data scavenge copy * mark it bad, restore state (old block) */ (*ll->markblockbad)(ll, db->block); db->block = state.oldblock; return errmsg; } /* * write error on target block * * if it is a replacement (state saved) * mark the new block bad, restore state and try again * * if it is not replaced (no state saved) * replace block, and try again */ if(state.oldblock >= 0) { (*ll->markblockbad)(ll, db->block); db->block = state.oldblock; } else { errmsg = logfsserverreplacedatablock(server, blockindex); if(errmsg) return errmsg; } goto reallocate; } mask = logfsdatapagemask(1, p); db->free &= ~mask; db->dirty |= mask; } /* well, we managed to write the data out */ errmsg = logfslogwrite(server, 1, e->qid.path, offset, thistime, now, e->u.file.cvers, muid, nil, &extent.flashaddr); /* * now we can dispose of the original data block, if any * this is regardless of whether we succeeded in writing a log message, as * if this block is not erased, there will be a duplicate */ disposeofoldblock(server, &state); } else { if(thistime > count) thistime = count; errmsg = logfslogwrite(server, 1, e->qid.path, offset, thistime, now, e->u.file.cvers, muid, buf, &extent.flashaddr); } /* * here if we failed to write the log message */ if(errmsg) return errmsg; if(server->trace > 1) print("logfsserverwrite: %d bytes at flashaddr 0x%.8ux\n", thistime, extent.flashaddr); extent.min = offset; extent.max = offset + thistime; errmsg = zappages(server, e, extent.min, extent.max); if(errmsg) return errmsg; errmsg = logfsextentlistinsert(e->u.file.extent, &extent, nil); if(errmsg) return errmsg; e->muid = muid; e->mtime = now; offset += thistime; if(e->u.file.length < offset) e->u.file.length = offset; count -= thistime; buf += thistime; e->qid.vers++; } return nil; }