livefiles_hfs_plugin/lf_hfs_btree_node_reserve.c

   1 //
   2 //  lf_hfs_btree_node_reserve.c
   3 //  livefiles_hfs
   4 //
   5 //  Created by Yakov Ben Zaken on 22/03/2018.
   6 //
   7
   8 #include <stdio.h>
   9 #include "lf_hfs_btrees_private.h"
  10 #include "lf_hfs_utils.h"
  11 #include "lf_hfs_vfsutils.h"
  12
  13 /*
  14  * B-tree Node Reserve
  15  *
  16  * BTReserveSpace
  17  * BTReleaseReserve
  18  * BTUpdateReserve
  19  *
  20  * Each kernel thread can have it's own reserve of b-tree
  21  * nodes. This reserve info is kept in a hash table.
  22  *
  23  * Don't forget to call BTReleaseReserve when you're finished
  24  * or you will leave stale node reserves in the hash.
  25  */
  26
  27
  28 /*
  29  * BE CAREFUL WHEN INCREASING THE SIZE OF THIS STRUCT!
  30  *
  31  * It must remain equal in size to the opaque cat_cookie_t
  32  * struct (in hfs_catalog.h).
  33  */
  34 struct nreserve {
  35     LIST_ENTRY(nreserve) nr_hash;  /* hash chain */
  36     int  nr_nodecnt;               /* count of nodes held in reserve */
  37     int  nr_newnodes;              /* nodes that were allocated */
  38     struct    vnode *nr_btvp;        /* b-tree file vnode */
  39     void  *nr_tag;                 /* unique tag (per thread) */
  40 };
  41
  42 #define NR_GET_TAG()    (pthread_self())
  43
  44 #define    NR_CACHE 17
  45
  46 #define NR_HASH(btvp, tag) \
  47 (&nr_hashtbl[((((intptr_t)(btvp)) >> 8) ^ ((intptr_t)(tag) >> 4)) & nr_hashmask])
  48
  49 LIST_HEAD(nodereserve, nreserve) *nr_hashtbl;
  50
  51 u_long nr_hashmask;
  52
  53 pthread_mutex_t  nr_mutex;
  54
  55 /* Internal Node Reserve Hash Routines (private) */
  56 static void nr_insert (struct vnode *, struct nreserve *nrp, int);
  57 static void nr_delete (struct vnode *, struct nreserve *nrp, int *);
  58 static void nr_update (struct vnode *, int);
  59
  60
  61 /*
  62  * BTReserveSetup - initialize the node reserve hash table
  63  */
  64 void BTReserveSetup(void)
  65 {
  66     if (sizeof(struct nreserve) != sizeof(cat_cookie_t))
  67     {
  68         LFHFS_LOG(LEVEL_ERROR,"BTReserveSetup: nreserve size != opaque struct size");
  69         hfs_assert(0);
  70     }
  71
  72     nr_hashtbl = hashinit(NR_CACHE, &nr_hashmask);
  73
  74     lf_lck_mtx_init(&nr_mutex);
  75 }
  76
  77
  78 /*
  79  * BTReserveSpace - obtain a node reserve (for current thread)
  80  *
  81  * Used by the Catalog Layer (hfs_catalog.c) to reserve space.
  82  *
  83  * When data is NULL, we only insure that there's enough space
  84  * but it is not reserved (assumes you keep the b-tree lock).
  85  */
  86 int
  87 BTReserveSpace(FCB *file, int operations, void* data)
  88 {
  89     BTreeControlBlock *btree;
  90     int rsrvNodes, availNodes, totalNodes;
  91     int height;
  92     int inserts, deletes;
  93     u_int32_t clumpsize;
  94     int err = 0;
  95
  96     btree = (BTreeControlBlockPtr)file->fcbBTCBPtr;
  97     clumpsize = file->ff_clumpsize;
  98
  99     REQUIRE_FILE_LOCK(btree->fileRefNum, true);
 100
 101     /*
 102      * The node reserve is based on the number of b-tree
 103      * operations (insert/deletes) and the height of the
 104      * tree.
 105      */
 106     height = btree->treeDepth;
 107     if (height < 2)
 108         height = 2;  /* prevent underflow in rsrvNodes calculation */
 109     inserts = operations & 0xffff;
 110     deletes = operations >> 16;
 111
 112     /*
 113      * Allow for at least one root split.
 114      *
 115      * Each delete operation can propogate a big key up the
 116      * index. This can cause a split at each level up.
 117      *
 118      * Each insert operation can cause a local split and a
 119      * split at each level up.
 120      */
 121     rsrvNodes = 1 + (deletes * (height - 2)) + (inserts * (height - 1));
 122
 123     availNodes = btree->freeNodes - btree->reservedNodes;
 124
 125     if (rsrvNodes > availNodes) {
 126         u_int32_t reqblks, freeblks, rsrvblks;
 127         uint32_t bt_rsrv;
 128         struct hfsmount *hfsmp;
 129
 130         /*
 131          * For UNIX conformance, we try and reserve the MIN of either 5% of
 132          * total file blocks or 10MB worth of blocks, for growing existing
 133          * files.  On non-HFS filesystems, creating a new directory entry may
 134          * not cause additional disk space to be allocated, but on HFS, creating
 135          * a new entry could cause the b-tree to grow.  As a result, we take
 136          * some precautions here to prevent that on configurations that try to
 137          * satisfy conformance.
 138          */
 139         hfsmp = VTOVCB(btree->fileRefNum);
 140         rsrvblks = (uint32_t)(((u_int64_t)hfsmp->allocLimit * 5) / 100);
 141         if (hfsmp->blockSize > HFS_BT_MAXRESERVE) {
 142             bt_rsrv = 1;
 143         }
 144         else {
 145             bt_rsrv = (HFS_BT_MAXRESERVE / hfsmp->blockSize);
 146         }
 147         rsrvblks = MIN(rsrvblks, bt_rsrv);
 148
 149         freeblks = hfs_freeblks(hfsmp, 0);
 150         if (freeblks <= rsrvblks) {
 151             /* When running low, disallow adding new items. */
 152             if ((inserts > 0) && (deletes == 0)) {
 153                 return (ENOSPC);
 154             }
 155             freeblks = 0;
 156         } else {
 157             freeblks -= rsrvblks;
 158         }
 159         reqblks = clumpsize / hfsmp->blockSize;
 160
 161         if (reqblks > freeblks) {
 162             reqblks = ((rsrvNodes - availNodes) * btree->nodeSize) / hfsmp->blockSize;
 163             /* When running low, disallow adding new items. */
 164             if ((reqblks > freeblks) && (inserts > 0) && (deletes == 0)) {
 165                 return (ENOSPC);
 166             }
 167             file->ff_clumpsize = freeblks * hfsmp->blockSize;
 168         }
 169         totalNodes = rsrvNodes + btree->totalNodes - availNodes;
 170
 171         /* See if we also need a map node */
 172         if (totalNodes > (int)CalcMapBits(btree)) {
 173             ++totalNodes;
 174         }
 175         if ((err = ExtendBTree(btree, totalNodes))) {
 176             goto out;
 177         }
 178     }
 179     /* Save this reserve if this is a persistent request. */
 180     if (data) {
 181         btree->reservedNodes += rsrvNodes;
 182         nr_insert(btree->fileRefNum, (struct nreserve *)data, rsrvNodes);
 183     }
 184 out:
 185     /* Put clump size back if it was changed. */
 186     if (file->ff_clumpsize != clumpsize)
 187         file->ff_clumpsize = clumpsize;
 188
 189     return (err);
 190 }
 191
 192
 193 /*
 194  * BTReleaseReserve - release the node reserve held by current thread
 195  *
 196  * Used by the Catalog Layer (hfs_catalog.c) to relinquish reserved space.
 197  */
 198 int
 199 BTReleaseReserve(FCB *file, void* data)
 200 {
 201     BTreeControlBlock *btree;
 202     int nodecnt;
 203
 204     btree = (BTreeControlBlockPtr)file->fcbBTCBPtr;
 205
 206     REQUIRE_FILE_LOCK(btree->fileRefNum, true);
 207
 208     nr_delete(btree->fileRefNum, (struct nreserve *)data, &nodecnt);
 209
 210     if (nodecnt)
 211         btree->reservedNodes -= nodecnt;
 212
 213     return (0);
 214 }
 215
 216 /*
 217  * BTUpdateReserve - update a node reserve for allocations that occurred.
 218  */
 219 void
 220 BTUpdateReserve(BTreeControlBlockPtr btreePtr, int nodes)
 221 {
 222     nr_update(btreePtr->fileRefNum, nodes);
 223 }
 224
 225
 226 /*----------------------------------------------------------------------------*/
 227 /* Node Reserve Hash Functions (private) */
 228
 229
 230 int nrinserts = 0;
 231 int nrdeletes = 0;
 232
 233 /*
 234  * Insert a new node reserve.
 235  */
 236 static void
 237 nr_insert(struct vnode * btvp, struct nreserve *nrp, int nodecnt)
 238 {
 239     struct nodereserve *nrhead;
 240     struct nreserve *tmp_nrp;
 241     void * tag = NR_GET_TAG();
 242
 243     /*
 244      * Check the cache - there may already be a reserve
 245      */
 246     lf_lck_mtx_lock(&nr_mutex);
 247     nrhead = NR_HASH(btvp, tag);
 248     for (tmp_nrp = nrhead->lh_first; tmp_nrp;
 249          tmp_nrp = tmp_nrp->nr_hash.le_next) {
 250         if ((tmp_nrp->nr_tag == tag) && (tmp_nrp->nr_btvp == btvp)) {
 251             nrp->nr_tag = 0;
 252             tmp_nrp->nr_nodecnt += nodecnt;
 253             lf_lck_mtx_unlock(&nr_mutex);
 254             return;
 255         }
 256     }
 257
 258     nrp->nr_nodecnt = nodecnt;
 259     nrp->nr_newnodes = 0;
 260     nrp->nr_btvp = btvp;
 261     nrp->nr_tag = tag;
 262     LIST_INSERT_HEAD(nrhead, nrp, nr_hash);
 263     ++nrinserts;
 264     lf_lck_mtx_unlock(&nr_mutex);
 265 }
 266
 267 /*
 268  * Delete a node reserve.
 269  */
 270 static void
 271 nr_delete(struct vnode * btvp, struct nreserve *nrp, int *nodecnt)
 272 {
 273     void * tag = NR_GET_TAG();
 274
 275     lf_lck_mtx_lock(&nr_mutex);
 276     if (nrp->nr_tag) {
 277         if ((nrp->nr_tag != tag) || (nrp->nr_btvp != btvp))
 278         {
 279             LFHFS_LOG(LEVEL_ERROR,"nr_delete: invalid NR (%p)", nrp);
 280             hfs_assert(0);
 281         }
 282         LIST_REMOVE(nrp, nr_hash);
 283         *nodecnt = nrp->nr_nodecnt;
 284         bzero(nrp, sizeof(struct nreserve));
 285         ++nrdeletes;
 286     } else {
 287         *nodecnt = 0;
 288     }
 289     lf_lck_mtx_unlock(&nr_mutex);
 290 }
 291
 292
 293 /*
 294  * Update a node reserve for any allocations that occurred.
 295  */
 296 static void
 297 nr_update(struct vnode * btvp, int nodecnt)
 298 {
 299     struct nodereserve *nrhead;
 300     struct nreserve *nrp;
 301     void* tag = NR_GET_TAG();
 302
 303     lf_lck_mtx_lock(&nr_mutex);
 304
 305     nrhead = NR_HASH(btvp, tag);
 306     for (nrp = nrhead->lh_first; nrp; nrp = nrp->nr_hash.le_next) {
 307         if ((nrp->nr_tag == tag) && (nrp->nr_btvp == btvp)) {
 308             nrp->nr_newnodes += nodecnt;
 309             break;
 310         }
 311     }
 312     lf_lck_mtx_unlock(&nr_mutex);
 313 }