diff options
Diffstat (limited to 'fs/block_dev.c')
| -rw-r--r-- | fs/block_dev.c | 202 |
1 files changed, 175 insertions, 27 deletions
diff --git a/fs/block_dev.c b/fs/block_dev.c index 197f9392184..1715d6b5f41 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -129,43 +129,191 @@ blkdev_get_block(struct inode *inode, sector_t iblock, return 0; } -static int -blkdev_get_blocks(struct inode *inode, sector_t iblock, - struct buffer_head *bh, int create) +static int blk_end_aio(struct bio *bio, unsigned int bytes_done, int error) { - sector_t end_block = max_block(I_BDEV(inode)); - unsigned long max_blocks = bh->b_size >> inode->i_blkbits; + struct kiocb *iocb = bio->bi_private; + atomic_t *bio_count = &iocb->ki_bio_count; - if ((iblock + max_blocks) > end_block) { - max_blocks = end_block - iblock; - if ((long)max_blocks <= 0) { - if (create) - return -EIO; /* write fully beyond EOF */ - /* - * It is a read which is fully beyond EOF. We return - * a !buffer_mapped buffer - */ - max_blocks = 0; - } + if (bio_data_dir(bio) == READ) + bio_check_pages_dirty(bio); + else { + bio_release_pages(bio); + bio_put(bio); + } + + /* iocb->ki_nbytes stores error code from LLDD */ + if (error) + iocb->ki_nbytes = -EIO; + + if (atomic_dec_and_test(bio_count)) { + if (iocb->ki_nbytes < 0) + aio_complete(iocb, iocb->ki_nbytes, 0); + else + aio_complete(iocb, iocb->ki_left, 0); } - bh->b_bdev = I_BDEV(inode); - bh->b_blocknr = iblock; - bh->b_size = max_blocks << inode->i_blkbits; - if (max_blocks) - set_buffer_mapped(bh); return 0; } +#define VEC_SIZE 16 +struct pvec { + unsigned short nr; + unsigned short idx; + struct page *page[VEC_SIZE]; +}; + +#define PAGES_SPANNED(addr, len) \ + (DIV_ROUND_UP((addr) + (len), PAGE_SIZE) - (addr) / PAGE_SIZE); + +/* + * get page pointer for user addr, we internally cache struct page array for + * (addr, count) range in pvec to avoid frequent call to get_user_pages. If + * internal page list is exhausted, a batch count of up to VEC_SIZE is used + * to get next set of page struct. + */ +static struct page *blk_get_page(unsigned long addr, size_t count, int rw, + struct pvec *pvec) +{ + int ret, nr_pages; + if (pvec->idx == pvec->nr) { + nr_pages = PAGES_SPANNED(addr, count); + nr_pages = min(nr_pages, VEC_SIZE); + down_read(¤t->mm->mmap_sem); + ret = get_user_pages(current, current->mm, addr, nr_pages, + rw == READ, 0, pvec->page, NULL); + up_read(¤t->mm->mmap_sem); + if (ret < 0) + return ERR_PTR(ret); + pvec->nr = ret; + pvec->idx = 0; + } + return pvec->page[pvec->idx++]; +} + static ssize_t blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, - loff_t offset, unsigned long nr_segs) -{ - struct file *file = iocb->ki_filp; - struct inode *inode = file->f_mapping->host; + loff_t pos, unsigned long nr_segs) +{ + struct inode *inode = iocb->ki_filp->f_mapping->host; + unsigned blkbits = blksize_bits(bdev_hardsect_size(I_BDEV(inode))); + unsigned blocksize_mask = (1 << blkbits) - 1; + unsigned long seg = 0; /* iov segment iterator */ + unsigned long nvec; /* number of bio vec needed */ + unsigned long cur_off; /* offset into current page */ + unsigned long cur_len; /* I/O len of current page, up to PAGE_SIZE */ + + unsigned long addr; /* user iovec address */ + size_t count; /* user iovec len */ + size_t nbytes = iocb->ki_nbytes = iocb->ki_left; /* total xfer size */ + loff_t size; /* size of block device */ + struct bio *bio; + atomic_t *bio_count = &iocb->ki_bio_count; + struct page *page; + struct pvec pvec; + + pvec.nr = 0; + pvec.idx = 0; + + if (pos & blocksize_mask) + return -EINVAL; + + size = i_size_read(inode); + if (pos + nbytes > size) { + nbytes = size - pos; + iocb->ki_left = nbytes; + } + + /* + * check first non-zero iov alignment, the remaining + * iov alignment is checked inside bio loop below. + */ + do { + addr = (unsigned long) iov[seg].iov_base; + count = min(iov[seg].iov_len, nbytes); + if (addr & blocksize_mask || count & blocksize_mask) + return -EINVAL; + } while (!count && ++seg < nr_segs); + atomic_set(bio_count, 1); + + while (nbytes) { + /* roughly estimate number of bio vec needed */ + nvec = (nbytes + PAGE_SIZE - 1) / PAGE_SIZE; + nvec = max(nvec, nr_segs - seg); + nvec = min(nvec, (unsigned long) BIO_MAX_PAGES); + + /* bio_alloc should not fail with GFP_KERNEL flag */ + bio = bio_alloc(GFP_KERNEL, nvec); + bio->bi_bdev = I_BDEV(inode); + bio->bi_end_io = blk_end_aio; + bio->bi_private = iocb; + bio->bi_sector = pos >> blkbits; +same_bio: + cur_off = addr & ~PAGE_MASK; + cur_len = PAGE_SIZE - cur_off; + if (count < cur_len) + cur_len = count; + + page = blk_get_page(addr, count, rw, &pvec); + if (unlikely(IS_ERR(page))) + goto backout; + + if (bio_add_page(bio, page, cur_len, cur_off)) { + pos += cur_len; + addr += cur_len; + count -= cur_len; + nbytes -= cur_len; + + if (count) + goto same_bio; + while (++seg < nr_segs) { + addr = (unsigned long) iov[seg].iov_base; + count = iov[seg].iov_len; + if (!count) + continue; + if (unlikely(addr & blocksize_mask || + count & blocksize_mask)) { + page = ERR_PTR(-EINVAL); + goto backout; + } + count = min(count, nbytes); + goto same_bio; + } + } - return blockdev_direct_IO_no_locking(rw, iocb, inode, I_BDEV(inode), - iov, offset, nr_segs, blkdev_get_blocks, NULL); + /* bio is ready, submit it */ + if (rw == READ) + bio_set_pages_dirty(bio); + atomic_inc(bio_count); + submit_bio(rw, bio); + } + +completion: + iocb->ki_left -= nbytes; + nbytes = iocb->ki_left; + iocb->ki_pos += nbytes; + + blk_run_address_space(inode->i_mapping); + if (atomic_dec_and_test(bio_count)) + aio_complete(iocb, nbytes, 0); + + return -EIOCBQUEUED; + +backout: + /* + * back out nbytes count constructed so far for this bio, + * we will throw away current bio. + */ + nbytes += bio->bi_size; + bio_release_pages(bio); + bio_put(bio); + + /* + * if no bio was submmitted, return the error code. + * otherwise, proceed with pending I/O completion. + */ + if (atomic_read(bio_count) == 1) + return PTR_ERR(page); + goto completion; } static int blkdev_writepage(struct page *page, struct writeback_control *wbc) |