/* * fs/logfs/dev_bdev.c - Device access methods for block devices * * As should be obvious for Linux kernel code, license is GPLv2 * * Copyright (c) 2005-2008 Joern Engel <joern@logfs.org> */ #include "logfs.h" #include <linux/bio.h> #include <linux/blkdev.h> #include <linux/buffer_head.h> #include <linux/gfp.h> #include <linux/prefetch.h> #define PAGE_OFS(ofs) ((ofs) & (PAGE_SIZE-1)) static void request_complete(struct bio *bio, int err) { complete((struct completion *)bio->bi_private); } static int sync_request(struct page *page, struct block_device *bdev, int rw) { struct bio bio; struct bio_vec bio_vec; struct completion complete; bio_init(&bio); bio.bi_io_vec = &bio_vec; bio_vec.bv_page = page; bio_vec.bv_len = PAGE_SIZE; bio_vec.bv_offset = 0; bio.bi_vcnt = 1; bio.bi_idx = 0; bio.bi_size = PAGE_SIZE; bio.bi_bdev = bdev; bio.bi_sector = page->index * (PAGE_SIZE >> 9); init_completion(&complete); bio.bi_private = &complete; bio.bi_end_io = request_complete; submit_bio(rw, &bio); wait_for_completion(&complete); return test_bit(BIO_UPTODATE, &bio.bi_flags) ? 0 : -EIO; } static int bdev_readpage(void *_sb, struct page *page) { struct super_block *sb = _sb; struct block_device *bdev = logfs_super(sb)->s_bdev; int err; err = sync_request(page, bdev, READ); if (err) { ClearPageUptodate(page); SetPageError(page); } else { SetPageUptodate(page); ClearPageError(page); } unlock_page(page); return err; } static DECLARE_WAIT_QUEUE_HEAD(wq); static void writeseg_end_io(struct bio *bio, int err) { const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags); struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1; struct super_block *sb = bio->bi_private; struct logfs_super *super = logfs_super(sb); struct page *page; BUG_ON(!uptodate); /* FIXME: Retry io or write elsewhere */ BUG_ON(err); BUG_ON(bio->bi_vcnt == 0); do { page = bvec->bv_page; if (--bvec >= bio->bi_io_vec) prefetchw(&bvec->bv_page->flags); end_page_writeback(page); page_cache_release(page); } while (bvec >= bio->bi_io_vec); bio_put(bio); if (atomic_dec_and_test(&super->s_pending_writes)) wake_up(&wq); } static int __bdev_writeseg(struct super_block *sb, u64 ofs, pgoff_t index, size_t nr_pages) { struct logfs_super *super = logfs_super(sb); struct address_space *mapping = super->s_mapping_inode->i_mapping; struct bio *bio; struct page *page; struct request_queue *q = bdev_get_queue(sb->s_bdev); unsigned int max_pages = queue_max_hw_sectors(q) >> (PAGE_SHIFT - 9); int i; if (max_pages > BIO_MAX_PAGES) max_pages = BIO_MAX_PAGES; bio = bio_alloc(GFP_NOFS, max_pages); BUG_ON(!bio); for (i = 0; i < nr_pages; i++) { if (i >= max_pages) { /* Block layer cannot split bios :( */ bio->bi_vcnt = i; bio->bi_idx = 0; bio->bi_size = i * PAGE_SIZE; bio->bi_bdev = super->s_bdev; bio->bi_sector = ofs >> 9; bio->bi_private = sb; bio->bi_end_io = writeseg_end_io; atomic_inc(&super->s_pending_writes); submit_bio(WRITE, bio); ofs += i * PAGE_SIZE; index += i; nr_pages -= i; i = 0; bio = bio_alloc(GFP_NOFS, max_pages); BUG_ON(!bio); } page = find_lock_page(mapping, index + i); BUG_ON(!page); bio->bi_io_vec[i].bv_page = page; bio->bi_io_vec[i].bv_len = PAGE_SIZE; bio->bi_io_vec[i].bv_offset = 0; BUG_ON(PageWriteback(page)); set_page_writeback(page); unlock_page(page); } bio->bi_vcnt = nr_pages; bio->bi_idx = 0; bio->bi_size = nr_pages * PAGE_SIZE; bio->bi_bdev = super->s_bdev; bio->bi_sector = ofs >> 9; bio->bi_private = sb; bio->bi_end_io = writeseg_end_io; atomic_inc(&super->s_pending_writes); submit_bio(WRITE, bio); return 0; } static void bdev_writeseg(struct super_block *sb, u64 ofs, size_t len) { struct logfs_super *super = logfs_super(sb); int head; BUG_ON(super->s_flags & LOGFS_SB_FLAG_RO); if (len == 0) { /* This can happen when the object fit perfectly into a * segment, the segment gets written per sync and subsequently * closed. */ return; } head = ofs & (PAGE_SIZE - 1); if (head) { ofs -= head; len += head; } len = PAGE_ALIGN(len); __bdev_writeseg(sb, ofs, ofs >> PAGE_SHIFT, len >> PAGE_SHIFT); } static void erase_end_io(struct bio *bio, int err) { const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags); struct super_block *sb = bio->bi_private; struct logfs_super *super = logfs_super(sb); BUG_ON(!uptodate); /* FIXME: Retry io or write elsewhere */ BUG_ON(err); BUG_ON(bio->bi_vcnt == 0); bio_put(bio); if (atomic_dec_and_test(&super->s_pending_writes)) wake_up(&wq); } static int do_erase(struct super_block *sb, u64 ofs, pgoff_t index, size_t nr_pages) { struct logfs_super *super = logfs_super(sb); struct bio *bio; struct request_queue *q = bdev_get_queue(sb->s_bdev); unsigned int max_pages = queue_max_hw_sectors(q) >> (PAGE_SHIFT - 9); int i; if (max_pages > BIO_MAX_PAGES) max_pages = BIO_MAX_PAGES; bio = bio_alloc(GFP_NOFS, max_pages); BUG_ON(!bio); for (i = 0; i < nr_pages; i++) { if (i >= max_pages) { /* Block layer cannot split bios :( */ bio->bi_vcnt = i; bio->bi_idx = 0; bio->bi_size = i * PAGE_SIZE; bio->bi_bdev = super->s_bdev; bio->bi_sector = ofs >> 9; bio->bi_private = sb; bio->bi_end_io = erase_end_io; atomic_inc(&super->s_pending_writes); submit_bio(WRITE, bio); ofs += i * PAGE_SIZE; index += i; nr_pages -= i; i = 0; bio = bio_alloc(GFP_NOFS, max_pages); BUG_ON(!bio); } bio->bi_io_vec[i].bv_page = super->s_erase_page; bio->bi_io_vec[i].bv_len = PAGE_SIZE; bio->bi_io_vec[i].bv_offset = 0; } bio->bi_vcnt = nr_pages; bio->bi_idx = 0; bio->bi_size = nr_pages * PAGE_SIZE; bio->bi_bdev = super->s_bdev; bio->bi_sector = ofs >> 9; bio->bi_private = sb; bio->bi_end_io = erase_end_io; atomic_inc(&super->s_pending_writes); submit_bio(WRITE, bio); return 0; } static int bdev_erase(struct super_block *sb, loff_t to, size_t len, int ensure_write) { struct logfs_super *super = logfs_super(sb); BUG_ON(to & (PAGE_SIZE - 1)); BUG_ON(len & (PAGE_SIZE - 1)); if (super->s_flags & LOGFS_SB_FLAG_RO) return -EROFS; if (ensure_write) { /* * Object store doesn't care whether erases happen or not. * But for the journal they are required. Otherwise a scan * can find an old commit entry and assume it is the current * one, travelling back in time. */ do_erase(sb, to, to >> PAGE_SHIFT, len >> PAGE_SHIFT); } return 0; } static void bdev_sync(struct super_block *sb) { struct logfs_super *super = logfs_super(sb); wait_event(wq, atomic_read(&super->s_pending_writes) == 0); } static struct page *bdev_find_first_sb(struct super_block *sb, u64 *ofs) { struct logfs_super *super = logfs_super(sb); struct address_space *mapping = super->s_mapping_inode->i_mapping; filler_t *filler = bdev_readpage; *ofs = 0; return read_cache_page(mapping, 0, filler, sb); } static struct page *bdev_find_last_sb(struct super_block *sb, u64 *ofs) { struct logfs_super *super = logfs_super(sb); struct address_space *mapping = super->s_mapping_inode->i_mapping; filler_t *filler = bdev_readpage; u64 pos = (super->s_bdev->bd_inode->i_size & ~0xfffULL) - 0x1000; pgoff_t index = pos >> PAGE_SHIFT; *ofs = pos; return read_cache_page(mapping, index, filler, sb); } static int bdev_write_sb(struct super_block *sb, struct page *page) { struct block_device *bdev = logfs_super(sb)->s_bdev; /* Nothing special to do for block devices. */ return sync_request(page, bdev, WRITE); } static void bdev_put_device(struct logfs_super *s) { blkdev_put(s->s_bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL); } static int bdev_can_write_buf(struct super_block *sb, u64 ofs) { return 0; } static const struct logfs_device_ops bd_devops = { .find_first_sb = bdev_find_first_sb, .find_last_sb = bdev_find_last_sb, .write_sb = bdev_write_sb, .readpage = bdev_readpage, .writeseg = bdev_writeseg, .erase = bdev_erase, .can_write_buf = bdev_can_write_buf, .sync = bdev_sync, .put_device = bdev_put_device, }; int logfs_get_sb_bdev(struct logfs_super *p, struct file_system_type *type, const char *devname) { struct block_device *bdev; bdev = blkdev_get_by_path(devname, FMODE_READ|FMODE_WRITE|FMODE_EXCL, type); if (IS_ERR(bdev)) return PTR_ERR(bdev); if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) { int mtdnr = MINOR(bdev->bd_dev); blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL); return logfs_get_sb_mtd(p, mtdnr); } p->s_bdev = bdev; p->s_mtd = NULL; p->s_devops = &bd_devops; return 0; }