/* * Copyright (c) 2008 Jakub Jermar * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * - Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * - 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. * - The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 THE AUTHOR 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. */ /** @addtogroup fs * @{ */ /** * @file fat_idx.c * @brief Layer for translating FAT entities to VFS node indices. */ #include "fat.h" #include "../../vfs/vfs.h" #include #include #include #include #include #include #include /** Each instance of this type describes one interval of freed VFS indices. */ typedef struct { link_t link; fs_index_t first; fs_index_t last; } freed_t; /** * Each instance of this type describes state of all VFS indices that * are currently unused. */ typedef struct { link_t link; devmap_handle_t devmap_handle; /** Next unassigned index. */ fs_index_t next; /** Number of remaining unassigned indices. */ uint64_t remaining; /** Sorted list of intervals of freed indices. */ link_t freed_head; } unused_t; /** Mutex protecting the list of unused structures. */ static FIBRIL_MUTEX_INITIALIZE(unused_lock); /** List of unused structures. */ static LIST_INITIALIZE(unused_head); static void unused_initialize(unused_t *u, devmap_handle_t devmap_handle) { link_initialize(&u->link); u->devmap_handle = devmap_handle; u->next = 0; u->remaining = ((uint64_t)((fs_index_t)-1)) + 1; list_initialize(&u->freed_head); } static unused_t *unused_find(devmap_handle_t devmap_handle, bool lock) { unused_t *u; link_t *l; if (lock) fibril_mutex_lock(&unused_lock); for (l = unused_head.next; l != &unused_head; l = l->next) { u = list_get_instance(l, unused_t, link); if (u->devmap_handle == devmap_handle) return u; } if (lock) fibril_mutex_unlock(&unused_lock); return NULL; } /** Mutex protecting the up_hash and ui_hash. */ static FIBRIL_MUTEX_INITIALIZE(used_lock); /** * Global hash table of all used fat_idx_t structures. * The index structures are hashed by the devmap_handle, parent node's first * cluster and index within the parent directory. */ static hash_table_t up_hash; #define UPH_BUCKETS_LOG 12 #define UPH_BUCKETS (1 << UPH_BUCKETS_LOG) #define UPH_DH_KEY 0 #define UPH_PFC_KEY 1 #define UPH_PDI_KEY 2 static hash_index_t pos_hash(unsigned long key[]) { devmap_handle_t devmap_handle = (devmap_handle_t)key[UPH_DH_KEY]; fat_cluster_t pfc = (fat_cluster_t)key[UPH_PFC_KEY]; unsigned pdi = (unsigned)key[UPH_PDI_KEY]; hash_index_t h; /* * The least significant half of all bits are the least significant bits * of the parent node's first cluster. * * The least significant half of the most significant half of all bits * are the least significant bits of the node's dentry index within the * parent directory node. * * The most significant half of the most significant half of all bits * are the least significant bits of the device handle. */ h = pfc & ((1 << (UPH_BUCKETS_LOG / 2)) - 1); h |= (pdi & ((1 << (UPH_BUCKETS_LOG / 4)) - 1)) << (UPH_BUCKETS_LOG / 2); h |= (devmap_handle & ((1 << (UPH_BUCKETS_LOG / 4)) - 1)) << (3 * (UPH_BUCKETS_LOG / 4)); return h; } static int pos_compare(unsigned long key[], hash_count_t keys, link_t *item) { devmap_handle_t devmap_handle = (devmap_handle_t)key[UPH_DH_KEY]; fat_cluster_t pfc; unsigned pdi; fat_idx_t *fidx = list_get_instance(item, fat_idx_t, uph_link); switch (keys) { case 1: return (devmap_handle == fidx->devmap_handle); case 3: pfc = (fat_cluster_t) key[UPH_PFC_KEY]; pdi = (unsigned) key[UPH_PDI_KEY]; return (devmap_handle == fidx->devmap_handle) && (pfc == fidx->pfc) && (pdi == fidx->pdi); default: assert((keys == 1) || (keys == 3)); } return 0; } static void pos_remove_callback(link_t *item) { /* nothing to do */ } static hash_table_operations_t uph_ops = { .hash = pos_hash, .compare = pos_compare, .remove_callback = pos_remove_callback, }; /** * Global hash table of all used fat_idx_t structures. * The index structures are hashed by the devmap_handle and index. */ static hash_table_t ui_hash; #define UIH_BUCKETS_LOG 12 #define UIH_BUCKETS (1 << UIH_BUCKETS_LOG) #define UIH_DH_KEY 0 #define UIH_INDEX_KEY 1 static hash_index_t idx_hash(unsigned long key[]) { devmap_handle_t devmap_handle = (devmap_handle_t)key[UIH_DH_KEY]; fs_index_t index = (fs_index_t)key[UIH_INDEX_KEY]; hash_index_t h; h = devmap_handle & ((1 << (UIH_BUCKETS_LOG / 2)) - 1); h |= (index & ((1 << (UIH_BUCKETS_LOG / 2)) - 1)) << (UIH_BUCKETS_LOG / 2); return h; } static int idx_compare(unsigned long key[], hash_count_t keys, link_t *item) { devmap_handle_t devmap_handle = (devmap_handle_t)key[UIH_DH_KEY]; fs_index_t index; fat_idx_t *fidx = list_get_instance(item, fat_idx_t, uih_link); switch (keys) { case 1: return (devmap_handle == fidx->devmap_handle); case 2: index = (fs_index_t) key[UIH_INDEX_KEY]; return (devmap_handle == fidx->devmap_handle) && (index == fidx->index); default: assert((keys == 1) || (keys == 2)); } return 0; } static void idx_remove_callback(link_t *item) { fat_idx_t *fidx = list_get_instance(item, fat_idx_t, uih_link); free(fidx); } static hash_table_operations_t uih_ops = { .hash = idx_hash, .compare = idx_compare, .remove_callback = idx_remove_callback, }; /** Allocate a VFS index which is not currently in use. */ static bool fat_index_alloc(devmap_handle_t devmap_handle, fs_index_t *index) { unused_t *u; assert(index); u = unused_find(devmap_handle, true); if (!u) return false; if (list_empty(&u->freed_head)) { if (u->remaining) { /* * There are no freed indices, allocate one directly * from the counter. */ *index = u->next++; --u->remaining; fibril_mutex_unlock(&unused_lock); return true; } } else { /* There are some freed indices which we can reuse. */ freed_t *f = list_get_instance(u->freed_head.next, freed_t, link); *index = f->first; if (f->first++ == f->last) { /* Destroy the interval. */ list_remove(&f->link); free(f); } fibril_mutex_unlock(&unused_lock); return true; } /* * We ran out of indices, which is extremely unlikely with FAT16, but * theoretically still possible (e.g. too many open unlinked nodes or * too many zero-sized nodes). */ fibril_mutex_unlock(&unused_lock); return false; } /** If possible, coalesce two intervals of freed indices. */ static void try_coalesce_intervals(link_t *l, link_t *r, link_t *cur) { freed_t *fl = list_get_instance(l, freed_t, link); freed_t *fr = list_get_instance(r, freed_t, link); if (fl->last + 1 == fr->first) { if (cur == l) { fl->last = fr->last; list_remove(r); free(r); } else { fr->first = fl->first; list_remove(l); free(l); } } } /** Free a VFS index, which is no longer in use. */ static void fat_index_free(devmap_handle_t devmap_handle, fs_index_t index) { unused_t *u; u = unused_find(devmap_handle, true); assert(u); if (u->next == index + 1) { /* The index can be returned directly to the counter. */ u->next--; u->remaining++; } else { /* * The index must be returned either to an existing freed * interval or a new interval must be created. */ link_t *lnk; freed_t *n; for (lnk = u->freed_head.next; lnk != &u->freed_head; lnk = lnk->next) { freed_t *f = list_get_instance(lnk, freed_t, link); if (f->first == index + 1) { f->first--; if (lnk->prev != &u->freed_head) try_coalesce_intervals(lnk->prev, lnk, lnk); fibril_mutex_unlock(&unused_lock); return; } if (f->last == index - 1) { f->last++; if (lnk->next != &u->freed_head) try_coalesce_intervals(lnk, lnk->next, lnk); fibril_mutex_unlock(&unused_lock); return; } if (index > f->first) { n = malloc(sizeof(freed_t)); /* TODO: sleep until allocation succeeds */ assert(n); link_initialize(&n->link); n->first = index; n->last = index; list_insert_before(&n->link, lnk); fibril_mutex_unlock(&unused_lock); return; } } /* The index will form the last interval. */ n = malloc(sizeof(freed_t)); /* TODO: sleep until allocation succeeds */ assert(n); link_initialize(&n->link); n->first = index; n->last = index; list_append(&n->link, &u->freed_head); } fibril_mutex_unlock(&unused_lock); } static int fat_idx_create(fat_idx_t **fidxp, devmap_handle_t devmap_handle) { fat_idx_t *fidx; fidx = (fat_idx_t *) malloc(sizeof(fat_idx_t)); if (!fidx) return ENOMEM; if (!fat_index_alloc(devmap_handle, &fidx->index)) { free(fidx); return ENOSPC; } link_initialize(&fidx->uph_link); link_initialize(&fidx->uih_link); fibril_mutex_initialize(&fidx->lock); fidx->devmap_handle = devmap_handle; fidx->pfc = FAT_CLST_RES0; /* no parent yet */ fidx->pdi = 0; fidx->nodep = NULL; *fidxp = fidx; return EOK; } int fat_idx_get_new(fat_idx_t **fidxp, devmap_handle_t devmap_handle) { fat_idx_t *fidx; int rc; fibril_mutex_lock(&used_lock); rc = fat_idx_create(&fidx, devmap_handle); if (rc != EOK) { fibril_mutex_unlock(&used_lock); return rc; } unsigned long ikey[] = { [UIH_DH_KEY] = devmap_handle, [UIH_INDEX_KEY] = fidx->index, }; hash_table_insert(&ui_hash, ikey, &fidx->uih_link); fibril_mutex_lock(&fidx->lock); fibril_mutex_unlock(&used_lock); *fidxp = fidx; return EOK; } fat_idx_t * fat_idx_get_by_pos(devmap_handle_t devmap_handle, fat_cluster_t pfc, unsigned pdi) { fat_idx_t *fidx; link_t *l; unsigned long pkey[] = { [UPH_DH_KEY] = devmap_handle, [UPH_PFC_KEY] = pfc, [UPH_PDI_KEY] = pdi, }; fibril_mutex_lock(&used_lock); l = hash_table_find(&up_hash, pkey); if (l) { fidx = hash_table_get_instance(l, fat_idx_t, uph_link); } else { int rc; rc = fat_idx_create(&fidx, devmap_handle); if (rc != EOK) { fibril_mutex_unlock(&used_lock); return NULL; } unsigned long ikey[] = { [UIH_DH_KEY] = devmap_handle, [UIH_INDEX_KEY] = fidx->index, }; fidx->pfc = pfc; fidx->pdi = pdi; hash_table_insert(&up_hash, pkey, &fidx->uph_link); hash_table_insert(&ui_hash, ikey, &fidx->uih_link); } fibril_mutex_lock(&fidx->lock); fibril_mutex_unlock(&used_lock); return fidx; } void fat_idx_hashin(fat_idx_t *idx) { unsigned long pkey[] = { [UPH_DH_KEY] = idx->devmap_handle, [UPH_PFC_KEY] = idx->pfc, [UPH_PDI_KEY] = idx->pdi, }; fibril_mutex_lock(&used_lock); hash_table_insert(&up_hash, pkey, &idx->uph_link); fibril_mutex_unlock(&used_lock); } void fat_idx_hashout(fat_idx_t *idx) { unsigned long pkey[] = { [UPH_DH_KEY] = idx->devmap_handle, [UPH_PFC_KEY] = idx->pfc, [UPH_PDI_KEY] = idx->pdi, }; fibril_mutex_lock(&used_lock); hash_table_remove(&up_hash, pkey, 3); fibril_mutex_unlock(&used_lock); } fat_idx_t * fat_idx_get_by_index(devmap_handle_t devmap_handle, fs_index_t index) { fat_idx_t *fidx = NULL; link_t *l; unsigned long ikey[] = { [UIH_DH_KEY] = devmap_handle, [UIH_INDEX_KEY] = index, }; fibril_mutex_lock(&used_lock); l = hash_table_find(&ui_hash, ikey); if (l) { fidx = hash_table_get_instance(l, fat_idx_t, uih_link); fibril_mutex_lock(&fidx->lock); } fibril_mutex_unlock(&used_lock); return fidx; } /** Destroy the index structure. * * @param idx The index structure to be destroyed. */ void fat_idx_destroy(fat_idx_t *idx) { unsigned long ikey[] = { [UIH_DH_KEY] = idx->devmap_handle, [UIH_INDEX_KEY] = idx->index, }; devmap_handle_t devmap_handle = idx->devmap_handle; fs_index_t index = idx->index; assert(idx->pfc == FAT_CLST_RES0); fibril_mutex_lock(&used_lock); /* * Since we can only free unlinked nodes, the index structure is not * present in the position hash (uph). We therefore hash it out from * the index hash only. */ hash_table_remove(&ui_hash, ikey, 2); fibril_mutex_unlock(&used_lock); /* Release the VFS index. */ fat_index_free(devmap_handle, index); /* The index structure itself is freed in idx_remove_callback(). */ } int fat_idx_init(void) { if (!hash_table_create(&up_hash, UPH_BUCKETS, 3, &uph_ops)) return ENOMEM; if (!hash_table_create(&ui_hash, UIH_BUCKETS, 2, &uih_ops)) { hash_table_destroy(&up_hash); return ENOMEM; } return EOK; } void fat_idx_fini(void) { /* We assume the hash tables are empty. */ hash_table_destroy(&up_hash); hash_table_destroy(&ui_hash); } int fat_idx_init_by_devmap_handle(devmap_handle_t devmap_handle) { unused_t *u; int rc = EOK; u = (unused_t *) malloc(sizeof(unused_t)); if (!u) return ENOMEM; unused_initialize(u, devmap_handle); fibril_mutex_lock(&unused_lock); if (!unused_find(devmap_handle, false)) { list_append(&u->link, &unused_head); } else { free(u); rc = EEXIST; } fibril_mutex_unlock(&unused_lock); return rc; } void fat_idx_fini_by_devmap_handle(devmap_handle_t devmap_handle) { unsigned long ikey[] = { [UIH_DH_KEY] = devmap_handle }; unsigned long pkey[] = { [UPH_DH_KEY] = devmap_handle }; /* * Remove this instance's index structure from up_hash and ui_hash. * Process up_hash first and ui_hash second because the index structure * is actually removed in idx_remove_callback(). */ fibril_mutex_lock(&used_lock); hash_table_remove(&up_hash, pkey, 1); hash_table_remove(&ui_hash, ikey, 1); fibril_mutex_unlock(&used_lock); /* * Free the unused and freed structures for this instance. */ unused_t *u = unused_find(devmap_handle, true); assert(u); list_remove(&u->link); fibril_mutex_unlock(&unused_lock); while (!list_empty(&u->freed_head)) { freed_t *f; f = list_get_instance(u->freed_head.next, freed_t, link); list_remove(&f->link); free(f); } free(u); } /** * @} */