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more robust gc #93
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@pellepl
pellepl committed Jul 31, 2016
1 parent 55c0ff4 commit 81fb3fa
Showing 1 changed file with 44 additions and 14 deletions.
58 changes: 44 additions & 14 deletions src/spiffs_gc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -356,6 +356,7 @@ typedef struct {
spiffs_obj_id cur_obj_id;
spiffs_span_ix cur_objix_spix;
spiffs_page_ix cur_objix_pix;
spiffs_page_ix cur_data_pix;
int stored_scan_entry_index;
u8_t obj_id_found;
} spiffs_gc;
Expand All @@ -375,10 +376,11 @@ typedef struct {
//
s32_t spiffs_gc_clean(spiffs *fs, spiffs_block_ix bix) {
s32_t res = SPIFFS_OK;
int entries_per_page = (SPIFFS_CFG_LOG_PAGE_SZ(fs) / sizeof(spiffs_obj_id));
const int entries_per_page = (SPIFFS_CFG_LOG_PAGE_SZ(fs) / sizeof(spiffs_obj_id));
// this is the global localizer being pushed and popped
int cur_entry = 0;
spiffs_obj_id *obj_lu_buf = (spiffs_obj_id *)fs->lu_work;
spiffs_gc gc;
spiffs_gc gc; // our stack frame/state
spiffs_page_ix cur_pix = 0;
spiffs_page_object_ix_header *objix_hdr = (spiffs_page_object_ix_header *)fs->work;
spiffs_page_object_ix *objix = (spiffs_page_object_ix *)fs->work;
Expand All @@ -397,7 +399,7 @@ s32_t spiffs_gc_clean(spiffs *fs, spiffs_block_ix bix) {

while (res == SPIFFS_OK && gc.state != FINISHED) {
SPIFFS_GC_DBG("gc_clean: state = %i entry:%i\n", gc.state, cur_entry);
gc.obj_id_found = 0;
gc.obj_id_found = 0; // reset (to no found data page)

// scan through lookup pages
int obj_lookup_page = cur_entry / entries_per_page;
Expand All @@ -408,7 +410,7 @@ s32_t spiffs_gc_clean(spiffs *fs, spiffs_block_ix bix) {
res = _spiffs_rd(fs, SPIFFS_OP_T_OBJ_LU | SPIFFS_OP_C_READ,
0, bix * SPIFFS_CFG_LOG_BLOCK_SZ(fs) + SPIFFS_PAGE_TO_PADDR(fs, obj_lookup_page),
SPIFFS_CFG_LOG_PAGE_SZ(fs), fs->lu_work);
// check each entry
// check each object lookup entry
while (scan && res == SPIFFS_OK &&
cur_entry - entry_offset < entries_per_page && cur_entry < (int)(SPIFFS_PAGES_PER_BLOCK(fs)-SPIFFS_OBJ_LOOKUP_PAGES(fs))) {
spiffs_obj_id obj_id = obj_lu_buf[cur_entry-entry_offset];
Expand All @@ -417,15 +419,20 @@ s32_t spiffs_gc_clean(spiffs *fs, spiffs_block_ix bix) {
// act upon object id depending on gc state
switch (gc.state) {
case FIND_OBJ_DATA:
// find a data page
if (obj_id != SPIFFS_OBJ_ID_DELETED && obj_id != SPIFFS_OBJ_ID_FREE &&
((obj_id & SPIFFS_OBJ_ID_IX_FLAG) == 0)) {
// found a data page, stop scanning and handle in switch case below
SPIFFS_GC_DBG("gc_clean: FIND_DATA state:%i - found obj id %04x\n", gc.state, obj_id);
gc.obj_id_found = 1;
gc.cur_obj_id = obj_id;
gc.cur_data_pix = cur_pix;
scan = 0;
}
break;
case MOVE_OBJ_DATA:
// evacuate found data pages for corresponding object index we have in memory,
// update memory representation
if (obj_id == gc.cur_obj_id) {
spiffs_page_header p_hdr;
res = _spiffs_rd(fs, SPIFFS_OP_T_OBJ_LU2 | SPIFFS_OP_C_READ,
Expand All @@ -447,7 +454,9 @@ s32_t spiffs_gc_clean(spiffs *fs, spiffs_block_ix bix) {
SPIFFS_CFG_LOG_PAGE_SZ(fs), fs->lu_work);
SPIFFS_CHECK_RES(res);
} else {
// page is deleted but not deleted in lookup, scrap it
// page is deleted but not deleted in lookup, scrap it -
// might seem unnecessary as we will erase this block, but
// we might get aborted
SPIFFS_GC_DBG("gc_clean: MOVE_DATA wipe objix %04x:%04x page %04x\n", obj_id, p_hdr.span_ix, cur_pix);
res = spiffs_page_delete(fs, cur_pix);
SPIFFS_CHECK_RES(res);
Expand All @@ -467,6 +476,7 @@ s32_t spiffs_gc_clean(spiffs *fs, spiffs_block_ix bix) {
}
break;
case MOVE_OBJ_IX:
// find and evacuate object index pages
if (obj_id != SPIFFS_OBJ_ID_DELETED && obj_id != SPIFFS_OBJ_ID_FREE &&
(obj_id & SPIFFS_OBJ_ID_IX_FLAG)) {
// found an index object id
Expand All @@ -488,7 +498,9 @@ s32_t spiffs_gc_clean(spiffs *fs, spiffs_block_ix bix) {
SPIFFS_CFG_LOG_PAGE_SZ(fs), fs->lu_work);
SPIFFS_CHECK_RES(res);
} else {
// page is deleted but not deleted in lookup, scrap it
// page is deleted but not deleted in lookup, scrap it -
// might seem unnecessary as we will erase this block, but
// we might get aborted
SPIFFS_GC_DBG("gc_clean: MOVE_OBJIX wipe objix %04x:%04x page %04x\n", obj_id, p_hdr.span_ix, cur_pix);
res = spiffs_page_delete(fs, cur_pix);
if (res == SPIFFS_OK) {
Expand All @@ -501,47 +513,64 @@ s32_t spiffs_gc_clean(spiffs *fs, spiffs_block_ix bix) {
default:
scan = 0;
break;
}
} // switch gc state
cur_entry++;
} // per entry
obj_lookup_page++;
obj_lookup_page++; // no need to check scan variable here, obj_lookup_page is set in start of loop
} // per object lookup page

if (res != SPIFFS_OK) break;

// state finalization and switch
switch (gc.state) {
case FIND_OBJ_DATA:
if (gc.obj_id_found) {
// handle found data page -
// find out corresponding obj ix page and load it to memory
spiffs_page_header p_hdr;
spiffs_page_ix objix_pix;
gc.stored_scan_entry_index = cur_entry;
cur_entry = 0;
gc.stored_scan_entry_index = cur_entry; // push cursor
cur_entry = 0; // restart scan from start
gc.state = MOVE_OBJ_DATA;
res = _spiffs_rd(fs, SPIFFS_OP_T_OBJ_LU2 | SPIFFS_OP_C_READ,
0, SPIFFS_PAGE_TO_PADDR(fs, cur_pix), sizeof(spiffs_page_header), (u8_t*)&p_hdr);
SPIFFS_CHECK_RES(res);
gc.cur_objix_spix = SPIFFS_OBJ_IX_ENTRY_SPAN_IX(fs, p_hdr.span_ix);
SPIFFS_GC_DBG("gc_clean: FIND_DATA find objix span_ix:%04x\n", gc.cur_objix_spix);
res = spiffs_obj_lu_find_id_and_span(fs, gc.cur_obj_id | SPIFFS_OBJ_ID_IX_FLAG, gc.cur_objix_spix, 0, &objix_pix);
if (res == SPIFFS_ERR_NOT_FOUND) {
// on borked systems we might get an ERR_NOT_FOUND here -
// this is handled by simply deleting the page as it is not referenced
// from anywhere
SPIFFS_GC_DBG("gc_clean: FIND_OBJ_DATA objix not found! Wipe page %04x\n", gc.cur_data_pix);
res = spiffs_page_delete(fs, gc.cur_data_pix);
SPIFFS_CHECK_RES(res);
// then we restore states and continue scanning for data pages
cur_entry = gc.stored_scan_entry_index; // pop cursor
gc.state = FIND_OBJ_DATA;
break; // done
}
SPIFFS_CHECK_RES(res);
SPIFFS_GC_DBG("gc_clean: FIND_DATA found object index at page %04x\n", objix_pix);
res = _spiffs_rd(fs, SPIFFS_OP_T_OBJ_LU2 | SPIFFS_OP_C_READ,
0, SPIFFS_PAGE_TO_PADDR(fs, objix_pix), SPIFFS_CFG_LOG_PAGE_SZ(fs), fs->work);
SPIFFS_CHECK_RES(res);
// cannot allow a gc if the presumed index in fact is no index, a
// check must run or lot of data may be lost
SPIFFS_VALIDATE_OBJIX(objix->p_hdr, gc.cur_obj_id | SPIFFS_OBJ_ID_IX_FLAG, gc.cur_objix_spix);
gc.cur_objix_pix = objix_pix;
} else {
// no more data pages found, passed thru all block, start evacuating object indices
gc.state = MOVE_OBJ_IX;
cur_entry = 0; // restart entry scan index
}
break;
case MOVE_OBJ_DATA: {
// store modified objix (hdr) page
// store modified objix (hdr) page residing in memory now that all
// data pages belonging to this object index and residing in the block
// we want to evacuate
spiffs_page_ix new_objix_pix;
gc.state = FIND_OBJ_DATA;
cur_entry = gc.stored_scan_entry_index;
cur_entry = gc.stored_scan_entry_index; // pop cursor
if (gc.cur_objix_spix == 0) {
// store object index header page
res = spiffs_object_update_index_hdr(fs, 0, gc.cur_obj_id | SPIFFS_OBJ_ID_IX_FLAG, gc.cur_objix_pix, fs->work, 0, 0, &new_objix_pix);
Expand All @@ -557,12 +586,13 @@ s32_t spiffs_gc_clean(spiffs *fs, spiffs_block_ix bix) {
}
break;
case MOVE_OBJ_IX:
// scanned thru all block, no more object indices found - our work here is done
gc.state = FINISHED;
break;
default:
cur_entry = 0;
break;
}
} // switch gc.state
SPIFFS_GC_DBG("gc_clean: state-> %i\n", gc.state);
} // while state != FINISHED

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