Read maps
parent
11f555de13
commit
bf609346c3
101
sftl.c
101
sftl.c
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@ -2,7 +2,7 @@
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* Simple log-structured translation layer for FTLed flash drives
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* like memory cards or USB sticks.
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*
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* (C) 2013 Vitaliy Filippov <vitalif at mail dot ru>
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* (C) 2013 Vitaliy Filippov <vitalif at mail d0t ru>
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* Redistributable under the terms of the GNU GPL 3.0+.
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*/
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@ -31,16 +31,21 @@ MODULE_DESCRIPTION("Log-structured translation layer for USB sticks and memory c
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MODULE_VERSION("0.1");
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static int major_num = 0;
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static int phy_sz = 512;
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static int clust_sz = 4096;
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static int clust_blocks = 4096/512;
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static int seg_sz = 512/16; /* in blocks */
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const u32 magic = 0x4C544673; // Magic: sFTL
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const int phy_sz = 512;
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const int clust_sz = 4096;
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const int clust_blocks = 4096/512;
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const int seg_sz = 512/16; /* (32) clusters */
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/* Mapping element */
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struct sftl_map {
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u32 magic, blk, ver, crc;
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u32 magic, block, ver, checksum;
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};
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/* Trivial checksum using some prime number */
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#define sftl_map_checksum(m) ((u32)((1+(m).block+((m).magic>>16))*(1+(m).ver+((m).magic&0xFFFF))*0xC4489EF5))
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/* The internal representation of our device */
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struct sftl_dev {
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u32 size; // device size in blocks
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@ -48,7 +53,7 @@ struct sftl_dev {
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u32 reserved_segs;
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u32 *map, *ver; // block mappings and versions
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u32 nextblk; // next free block pointer
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u32 freeblks, freesegs; // free block count, free segment count
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u32 freeclust, freesegs; // free block count, free segment count
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struct gendisk *gd;
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struct block_device *blkdev;
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struct request_queue *queue;
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@ -78,6 +83,7 @@ static void sftl_transfer(struct sftl_dev *dev, sector_t sector,
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INFO("Beyond-end write (starting sector = %ld, count = %ld)", offset, nblocks);
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return;
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}
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// TODO
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}
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@ -195,6 +201,56 @@ static void endFunc_tryKM2(struct bio *bb, int err)
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}
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}
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static void sync_read(struct block_device *bdev, unsigned sector, void *buf, unsigned len)
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{
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struct bio *bb;
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struct request_queue *q;
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DECLARE_COMPLETION_ONSTACK(waithandle);
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q = bdev_get_queue(bdev);
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bb = bio_map_kern(q, buf, len, GFP_KERNEL);
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if (IS_ERR(bb))
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return;
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bb->bi_sector = sector;
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bb->bi_bdev = bdev;
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bb->bi_private = &waithandle;
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bb->bi_end_io = endFunc_tryKM2;
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submit_bio(READ, bb);
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if (!(bb->bi_flags & (1 << BIO_UPTODATE)))
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{
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bio_put(bb);
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return;
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}
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wait_for_completion(&waithandle);
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bio_put(bb);
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}
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static void read_maps(struct sftl_dev *dev)
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{
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struct sftl_map *buf = kmalloc(phy_sz, GFP_KERNEL);
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int i, j, seg;
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INFO("reading translation maps");
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for (i = 0; i < dev->segs; i++)
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{
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sync_read(dev->blkdev, i*(seg_sz*clust_blocks+1), buf, phy_sz);
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for (seg = 1, j = 0; j < seg_sz; j++)
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{
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if (buf[j].magic == magic && buf[j].checksum == sftl_map_checksum(buf[j]))
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{
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dev->map[i*seg_sz+j] = buf[j].block;
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dev->ver[i*seg_sz+j] = buf[j].ver;
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seg = 0;
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}
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else
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{
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dev->ver[i*seg_sz+j] = 0;
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dev->freeclust++;
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}
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}
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dev->freesegs += seg;
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}
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kfree(buf);
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}
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static struct sftl_dev *add_device(char *devname)
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{
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const fmode_t mode = FMODE_READ | FMODE_WRITE | FMODE_EXCL;
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@ -232,9 +288,11 @@ static struct sftl_dev *add_device(char *devname)
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t = dev->blkdev->bd_inode->i_size;
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do_div(t, clust_sz*seg_sz + phy_sz);
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dev->segs = (uint32_t)t; //!!!
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dev->segs = t;
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dev->size = dev->segs * seg_sz * clust_blocks;
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dev->reserved_segs = seg_sz * (seg_sz+1);
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dev->map = vmalloc(sizeof(u32) * dev->size);
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dev->ver = vmalloc(sizeof(u32) * dev->size);
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/* Get a request queue */
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spin_lock_init(&dev->spinlock);
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@ -265,32 +323,15 @@ static struct sftl_dev *add_device(char *devname)
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snprintf(dev->gd->disk_name, 32, "sftl%d", index);
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set_capacity(dev->gd, dev->size);
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dev->gd->queue = dev->queue;
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INFO("gd = %d %d %d", dev->gd->minors, dev->gd->major, dev->gd->first_minor);
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add_disk(dev->gd);
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/* Read maps from the device */
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struct bio *bb;
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DECLARE_COMPLETION_ONSTACK(waithandle);
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bb = bio_map_kern(bdev->bd_disk->queue, buf, phy_sz, GFP_KERNEL);
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if (IS_ERR(bb))
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{
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vfree(buf);
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return;
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}
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bb->bi_sector = 0;
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bb->bi_bdev = bdev;
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bb->bi_private = &waithandle;
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bb->bi_end_io = endFunc_tryKM2;
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submit_bio(READ, bb);
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if (!(bb->bi_flags & (1 << BIO_UPTODATE)))
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{
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bio_put(bb);
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vfree(buf);
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return;
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}
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read_maps(dev);
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/* Add disk */
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add_disk(dev->gd);
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list_add(&dev->list, &sftl_device_list);
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INFO("%s: translating %s; %d sectors", dev->gd->disk_name, devname, dev->size);
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INFO("%s: translating %s; %d sectors; %d free", dev->gd->disk_name, devname, dev->size, dev->freeclust*clust_blocks);
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return dev;
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devinit_err:
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