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make sure that page isolation is called after erasing a sector in reluctant GC.

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simplified the GC logic a bit.
This commit is contained in:
nvt-se 2009-04-29 13:15:59 +00:00
parent 3c68862599
commit 17fa2f1618
1 changed files with 43 additions and 33 deletions
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76
core/cfs/cfs-coffee.c
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@ -183,8 +183,9 @@ absolute_offset(coffee_page_t page, cfs_offset_t offset)
return page * COFFEE_PAGE_SIZE + sizeof(struct file_header) + offset;
}
/*---------------------------------------------------------------------------*/
static void
get_sector_status(uint16_t sector, struct sector_stats *stats) {
static coffee_page_t
get_sector_status(uint16_t sector, struct sector_stats *stats)
{
static coffee_page_t skip_pages;
static char last_pages_are_active;
struct file_header hdr;
@ -197,36 +198,15 @@ get_sector_status(uint16_t sector, struct sector_stats *stats) {
if(sector == 0) {
skip_pages = 0;
last_pages_are_active = 0;
} else if(skip_pages > COFFEE_PAGES_PER_SECTOR) {
skip_pages -= COFFEE_PAGES_PER_SECTOR;
if(last_pages_are_active) {
stats->active = COFFEE_PAGES_PER_SECTOR;
stats->obsolete = 0;
} else {
stats->active = 0;
stats->obsolete = COFFEE_PAGES_PER_SECTOR;
}
stats->free = 0;
return;
}
sector_start = sector * COFFEE_SECTOR_SIZE / COFFEE_PAGE_SIZE;
sector_end = sector_start + COFFEE_SECTOR_SIZE / COFFEE_PAGE_SIZE;
sector_start = sector * COFFEE_PAGES_PER_SECTOR;
sector_end = sector_start + COFFEE_PAGES_PER_SECTOR;
if(last_pages_are_active) {
active = skip_pages;
active = skip_pages & (COFFEE_PAGES_PER_SECTOR - 1);
} else {
obsolete = skip_pages;
/* Split an obsolete file starting in the previous sector and mark
the following pages as isolated. */
memset(&hdr, 0, sizeof(hdr));
hdr.flags = HDR_FLAG_ALLOCATED | HDR_FLAG_ISOLATED;
for(page = 0; page < skip_pages; page++) {
write_header(&hdr, sector_start + page);
}
PRINTF("Coffee: Isolated %u pages starting in sector %d\n",
(unsigned)skip_pages, (int)sector);
obsolete = skip_pages & (COFFEE_PAGES_PER_SECTOR - 1);
}
for(page = sector_start + skip_pages; page < sector_end;) {
@ -243,7 +223,7 @@ get_sector_status(uint16_t sector, struct sector_stats *stats) {
page += hdr.max_pages;
obsolete += hdr.max_pages;
} else {
free = COFFEE_PAGES_PER_SECTOR - active - obsolete;
free = sector_end - page;
break;
}
}
@ -260,6 +240,28 @@ get_sector_status(uint16_t sector, struct sector_stats *stats) {
stats->active = active;
stats->obsolete = obsolete;
stats->free = free;
return last_pages_are_active ? 0 : skip_pages;
}
/*---------------------------------------------------------------------------*/
static void
isolate_pages(coffee_page_t start, coffee_page_t skip_pages)
{
struct file_header hdr;
coffee_page_t page;
/* Split an obsolete file starting in the previous sector and mark
the following pages as isolated. */
memset(&hdr, 0, sizeof(hdr));
hdr.flags = HDR_FLAG_ALLOCATED | HDR_FLAG_ISOLATED;
/* Isolation starts from the next sector. */
for(page = 0; page < skip_pages; page++) {
write_header(&hdr, start + page);
}
PRINTF("Coffee: Isolated %u pages starting in sector %d\n",
(unsigned)skip_pages, (int)start / COFFEE_PAGES_PER_SECTOR);
}
/*---------------------------------------------------------------------------*/
static void
@ -267,7 +269,7 @@ collect_garbage(int mode)
{
uint16_t sector;
struct sector_stats stats;
coffee_page_t first_page;
coffee_page_t first_page, skip_pages;
watchdog_stop();
@ -278,20 +280,28 @@ collect_garbage(int mode)
* erasable if there are only free or obsolete pages in it.
*/
for(sector = 0; sector < COFFEE_SECTOR_COUNT; sector++) {
get_sector_status(sector, &stats);
skip_pages = get_sector_status(sector, &stats);
PRINTF("Coffee: Sector %u has %u active, %u free, and %u obsolete pages.\n",
sector, (unsigned)stats.active, (unsigned)stats.free, (unsigned)stats.obsolete);
if(stats.active > 0) {
continue;
}
if((mode == GC_RELUCTANT && stats.free == 0) ||
(mode == GC_GREEDY && stats.obsolete > 0)) {
COFFEE_ERASE(sector);
PRINTF("Coffee: Erased sector %d!\n", sector);
(mode == GC_GREEDY && stats.obsolete > 0)) {
first_page = sector * COFFEE_PAGES_PER_SECTOR;
if(first_page < *next_free) {
*next_free = first_page;
}
if(skip_pages > 0) {
isolate_pages(first_page + COFFEE_PAGES_PER_SECTOR, skip_pages);
}
COFFEE_ERASE(sector);
PRINTF("Coffee: Erased sector %d!\n", sector);
if(mode == GC_RELUCTANT) {
break;
}