0,0 → 1,556 |
/* |
* 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 <errno.h> |
#include <string.h> |
#include <libadt/hash_table.h> |
#include <libadt/list.h> |
#include <assert.h> |
#include <futex.h> |
|
/** 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; |
dev_handle_t dev_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; |
|
/** Futex protecting the list of unused structures. */ |
static futex_t unused_futex = FUTEX_INITIALIZER; |
|
/** List of unused structures. */ |
static LIST_INITIALIZE(unused_head); |
|
static void unused_initialize(unused_t *u, dev_handle_t dev_handle) |
{ |
link_initialize(&u->link); |
u->dev_handle = dev_handle; |
u->next = 0; |
u->remaining = ((uint64_t)((fs_index_t)-1)) + 1; |
list_initialize(&u->freed_head); |
} |
|
static unused_t *unused_find(dev_handle_t dev_handle, bool lock) |
{ |
unused_t *u; |
link_t *l; |
|
if (lock) |
futex_down(&unused_futex); |
for (l = unused_head.next; l != &unused_head; l = l->next) { |
u = list_get_instance(l, unused_t, link); |
if (u->dev_handle == dev_handle) |
return u; |
} |
if (lock) |
futex_up(&unused_futex); |
return NULL; |
} |
|
/** Futex protecting the up_hash and ui_hash. */ |
static futex_t used_futex = FUTEX_INITIALIZER; |
|
/** |
* Global hash table of all used fat_idx_t structures. |
* The index structures are hashed by the dev_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[]) |
{ |
dev_handle_t dev_handle = (dev_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 |= (dev_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) |
{ |
dev_handle_t dev_handle = (dev_handle_t)key[UPH_DH_KEY]; |
fat_cluster_t pfc = (fat_cluster_t)key[UPH_PFC_KEY]; |
unsigned pdi = (unsigned)key[UPH_PDI_KEY]; |
fat_idx_t *fidx = list_get_instance(item, fat_idx_t, uph_link); |
|
return (dev_handle == fidx->dev_handle) && (pfc == fidx->pfc) && |
(pdi == fidx->pdi); |
} |
|
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 dev_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[]) |
{ |
dev_handle_t dev_handle = (dev_handle_t)key[UIH_DH_KEY]; |
fs_index_t index = (fs_index_t)key[UIH_INDEX_KEY]; |
|
hash_index_t h; |
|
h = dev_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) |
{ |
dev_handle_t dev_handle = (dev_handle_t)key[UIH_DH_KEY]; |
fs_index_t index = (fs_index_t)key[UIH_INDEX_KEY]; |
fat_idx_t *fidx = list_get_instance(item, fat_idx_t, uih_link); |
|
return (dev_handle == fidx->dev_handle) && (index == fidx->index); |
} |
|
static void idx_remove_callback(link_t *item) |
{ |
/* nothing to do */ |
} |
|
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(dev_handle_t dev_handle, fs_index_t *index) |
{ |
unused_t *u; |
|
assert(index); |
u = unused_find(dev_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; |
futex_up(&unused_futex); |
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); |
} |
futex_up(&unused_futex); |
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). |
*/ |
futex_up(&unused_futex); |
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(dev_handle_t dev_handle, fs_index_t index) |
{ |
unused_t *u; |
|
u = unused_find(dev_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); |
futex_up(&unused_futex); |
return; |
} |
if (f->last == index - 1) { |
f->last++; |
if (lnk->next != &u->freed_head) |
try_coalesce_intervals(lnk, lnk->next, |
lnk); |
futex_up(&unused_futex); |
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); |
futex_up(&unused_futex); |
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); |
} |
futex_up(&unused_futex); |
} |
|
static fat_idx_t *fat_idx_create(dev_handle_t dev_handle) |
{ |
fat_idx_t *fidx; |
|
fidx = (fat_idx_t *) malloc(sizeof(fat_idx_t)); |
if (!fidx) |
return NULL; |
if (!fat_index_alloc(dev_handle, &fidx->index)) { |
free(fidx); |
return NULL; |
} |
|
link_initialize(&fidx->uph_link); |
link_initialize(&fidx->uih_link); |
futex_initialize(&fidx->lock, 1); |
fidx->dev_handle = dev_handle; |
fidx->pfc = FAT_CLST_RES0; /* no parent yet */ |
fidx->pdi = 0; |
fidx->nodep = NULL; |
|
return fidx; |
} |
|
fat_idx_t *fat_idx_get_new(dev_handle_t dev_handle) |
{ |
fat_idx_t *fidx; |
|
futex_down(&used_futex); |
fidx = fat_idx_create(dev_handle); |
if (!fidx) { |
futex_up(&used_futex); |
return NULL; |
} |
|
unsigned long ikey[] = { |
[UIH_DH_KEY] = dev_handle, |
[UIH_INDEX_KEY] = fidx->index, |
}; |
|
hash_table_insert(&ui_hash, ikey, &fidx->uih_link); |
futex_down(&fidx->lock); |
futex_up(&used_futex); |
|
return fidx; |
} |
|
fat_idx_t * |
fat_idx_get_by_pos(dev_handle_t dev_handle, fat_cluster_t pfc, unsigned pdi) |
{ |
fat_idx_t *fidx; |
link_t *l; |
unsigned long pkey[] = { |
[UPH_DH_KEY] = dev_handle, |
[UPH_PFC_KEY] = pfc, |
[UPH_PDI_KEY] = pdi, |
}; |
|
futex_down(&used_futex); |
l = hash_table_find(&up_hash, pkey); |
if (l) { |
fidx = hash_table_get_instance(l, fat_idx_t, uph_link); |
} else { |
fidx = fat_idx_create(dev_handle); |
if (!fidx) { |
futex_up(&used_futex); |
return NULL; |
} |
|
unsigned long ikey[] = { |
[UIH_DH_KEY] = dev_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); |
} |
futex_down(&fidx->lock); |
futex_up(&used_futex); |
|
return fidx; |
} |
|
void fat_idx_hashin(fat_idx_t *idx) |
{ |
unsigned long pkey[] = { |
[UPH_DH_KEY] = idx->dev_handle, |
[UPH_PFC_KEY] = idx->pfc, |
[UPH_PDI_KEY] = idx->pdi, |
}; |
|
futex_down(&used_futex); |
hash_table_insert(&up_hash, pkey, &idx->uph_link); |
futex_up(&used_futex); |
} |
|
void fat_idx_hashout(fat_idx_t *idx) |
{ |
unsigned long pkey[] = { |
[UPH_DH_KEY] = idx->dev_handle, |
[UPH_PFC_KEY] = idx->pfc, |
[UPH_PDI_KEY] = idx->pdi, |
}; |
|
futex_down(&used_futex); |
hash_table_remove(&up_hash, pkey, 3); |
futex_up(&used_futex); |
} |
|
fat_idx_t * |
fat_idx_get_by_index(dev_handle_t dev_handle, fs_index_t index) |
{ |
fat_idx_t *fidx = NULL; |
link_t *l; |
unsigned long ikey[] = { |
[UIH_DH_KEY] = dev_handle, |
[UIH_INDEX_KEY] = index, |
}; |
|
futex_down(&used_futex); |
l = hash_table_find(&ui_hash, ikey); |
if (l) { |
fidx = hash_table_get_instance(l, fat_idx_t, uih_link); |
futex_down(&fidx->lock); |
} |
futex_up(&used_futex); |
|
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->dev_handle, |
[UIH_INDEX_KEY] = idx->index, |
}; |
|
assert(idx->pfc == FAT_CLST_RES0); |
|
futex_down(&used_futex); |
/* |
* 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); |
futex_up(&used_futex); |
/* Release the VFS index. */ |
fat_index_free(idx->dev_handle, idx->index); |
/* Deallocate the structure. */ |
free(idx); |
} |
|
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_dev_handle(dev_handle_t dev_handle) |
{ |
unused_t *u; |
int rc = EOK; |
|
u = (unused_t *) malloc(sizeof(unused_t)); |
if (!u) |
return ENOMEM; |
unused_initialize(u, dev_handle); |
futex_down(&unused_futex); |
if (!unused_find(dev_handle, false)) |
list_append(&u->link, &unused_head); |
else |
rc = EEXIST; |
futex_up(&unused_futex); |
return rc; |
} |
|
void fat_idx_fini_by_dev_handle(dev_handle_t dev_handle) |
{ |
unused_t *u; |
|
u = unused_find(dev_handle, true); |
assert(u); |
list_remove(&u->link); |
futex_up(&unused_futex); |
|
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); |
} |
|
/** |
* @} |
*/ |