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block: loop: switch to VFS ITER_BVEC
Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Christoph Hellwig
Al Viro
parent
6683de3886
commit
aa4d86163e
@ -88,28 +88,6 @@ static int part_shift;
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static struct workqueue_struct *loop_wq;
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/*
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* Transfer functions
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*/
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static int transfer_none(struct loop_device *lo, int cmd,
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struct page *raw_page, unsigned raw_off,
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struct page *loop_page, unsigned loop_off,
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int size, sector_t real_block)
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{
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char *raw_buf = kmap_atomic(raw_page) + raw_off;
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char *loop_buf = kmap_atomic(loop_page) + loop_off;
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if (cmd == READ)
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memcpy(loop_buf, raw_buf, size);
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else
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memcpy(raw_buf, loop_buf, size);
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kunmap_atomic(loop_buf);
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kunmap_atomic(raw_buf);
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cond_resched();
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return 0;
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}
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static int transfer_xor(struct loop_device *lo, int cmd,
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struct page *raw_page, unsigned raw_off,
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struct page *loop_page, unsigned loop_off,
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@ -148,7 +126,6 @@ static int xor_init(struct loop_device *lo, const struct loop_info64 *info)
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static struct loop_func_table none_funcs = {
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.number = LO_CRYPT_NONE,
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.transfer = transfer_none,
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};
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static struct loop_func_table xor_funcs = {
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@ -215,209 +192,171 @@ lo_do_transfer(struct loop_device *lo, int cmd,
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struct page *lpage, unsigned loffs,
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int size, sector_t rblock)
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{
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if (unlikely(!lo->transfer))
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int ret;
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ret = lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock);
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if (likely(!ret))
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return 0;
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return lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock);
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printk_ratelimited(KERN_ERR
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"loop: Transfer error at byte offset %llu, length %i.\n",
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(unsigned long long)rblock << 9, size);
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return ret;
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}
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/**
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* __do_lo_send_write - helper for writing data to a loop device
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*
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* This helper just factors out common code between do_lo_send_direct_write()
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* and do_lo_send_write().
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*/
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static int __do_lo_send_write(struct file *file,
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u8 *buf, const int len, loff_t pos)
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static int lo_write_bvec(struct file *file, struct bio_vec *bvec, loff_t *ppos)
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{
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struct kvec kvec = {.iov_base = buf, .iov_len = len};
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struct iov_iter from;
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struct iov_iter i;
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ssize_t bw;
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iov_iter_kvec(&from, ITER_KVEC | WRITE, &kvec, 1, len);
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iov_iter_bvec(&i, ITER_BVEC, bvec, 1, bvec->bv_len);
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file_start_write(file);
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bw = vfs_iter_write(file, &from, &pos);
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bw = vfs_iter_write(file, &i, ppos);
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file_end_write(file);
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if (likely(bw == len))
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if (likely(bw == bvec->bv_len))
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return 0;
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printk_ratelimited(KERN_ERR "loop: Write error at byte offset %llu, length %i.\n",
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(unsigned long long)pos, len);
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printk_ratelimited(KERN_ERR
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"loop: Write error at byte offset %llu, length %i.\n",
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(unsigned long long)*ppos, bvec->bv_len);
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if (bw >= 0)
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bw = -EIO;
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return bw;
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}
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/**
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* do_lo_send_direct_write - helper for writing data to a loop device
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*
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* This is the fast, non-transforming version that does not need double
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* buffering.
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*/
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static int do_lo_send_direct_write(struct loop_device *lo,
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struct bio_vec *bvec, loff_t pos, struct page *page)
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static int lo_write_simple(struct loop_device *lo, struct request *rq,
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loff_t pos)
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{
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ssize_t bw = __do_lo_send_write(lo->lo_backing_file,
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kmap(bvec->bv_page) + bvec->bv_offset,
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bvec->bv_len, pos);
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kunmap(bvec->bv_page);
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struct bio_vec bvec;
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struct req_iterator iter;
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int ret = 0;
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rq_for_each_segment(bvec, rq, iter) {
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ret = lo_write_bvec(lo->lo_backing_file, &bvec, &pos);
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if (ret < 0)
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break;
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cond_resched();
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return bw;
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}
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/**
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* do_lo_send_write - helper for writing data to a loop device
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*
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return ret;
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}
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/*
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* This is the slow, transforming version that needs to double buffer the
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* data as it cannot do the transformations in place without having direct
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* access to the destination pages of the backing file.
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*/
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static int do_lo_send_write(struct loop_device *lo, struct bio_vec *bvec,
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loff_t pos, struct page *page)
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static int lo_write_transfer(struct loop_device *lo, struct request *rq,
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loff_t pos)
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{
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int ret = lo_do_transfer(lo, WRITE, page, 0, bvec->bv_page,
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bvec->bv_offset, bvec->bv_len, pos >> 9);
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if (likely(!ret))
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return __do_lo_send_write(lo->lo_backing_file,
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page_address(page), bvec->bv_len,
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pos);
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printk_ratelimited(KERN_ERR "loop: Transfer error at byte offset %llu, "
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"length %i.\n", (unsigned long long)pos, bvec->bv_len);
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if (ret > 0)
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ret = -EIO;
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return ret;
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}
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static int lo_send(struct loop_device *lo, struct request *rq, loff_t pos)
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{
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int (*do_lo_send)(struct loop_device *, struct bio_vec *, loff_t,
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struct page *page);
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struct bio_vec bvec;
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struct bio_vec bvec, b;
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struct req_iterator iter;
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struct page *page = NULL;
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struct page *page;
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int ret = 0;
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if (lo->transfer != transfer_none) {
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page = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
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page = alloc_page(GFP_NOIO);
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if (unlikely(!page))
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goto fail;
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kmap(page);
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do_lo_send = do_lo_send_write;
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} else {
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do_lo_send = do_lo_send_direct_write;
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}
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return -ENOMEM;
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rq_for_each_segment(bvec, rq, iter) {
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ret = do_lo_send(lo, &bvec, pos, page);
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ret = lo_do_transfer(lo, WRITE, page, 0, bvec.bv_page,
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bvec.bv_offset, bvec.bv_len, pos >> 9);
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if (unlikely(ret))
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break;
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b.bv_page = page;
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b.bv_offset = 0;
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b.bv_len = bvec.bv_len;
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ret = lo_write_bvec(lo->lo_backing_file, &b, &pos);
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if (ret < 0)
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break;
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pos += bvec.bv_len;
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}
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if (page) {
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kunmap(page);
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__free_page(page);
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}
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out:
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return ret;
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fail:
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printk_ratelimited(KERN_ERR "loop: Failed to allocate temporary page for write.\n");
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ret = -ENOMEM;
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goto out;
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}
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struct lo_read_data {
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struct loop_device *lo;
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struct page *page;
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unsigned offset;
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int bsize;
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};
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static int
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lo_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
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struct splice_desc *sd)
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{
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struct lo_read_data *p = sd->u.data;
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struct loop_device *lo = p->lo;
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struct page *page = buf->page;
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sector_t IV;
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int size;
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IV = ((sector_t) page->index << (PAGE_CACHE_SHIFT - 9)) +
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(buf->offset >> 9);
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size = sd->len;
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if (size > p->bsize)
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size = p->bsize;
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if (lo_do_transfer(lo, READ, page, buf->offset, p->page, p->offset, size, IV)) {
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printk_ratelimited(KERN_ERR "loop: transfer error block %ld\n",
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page->index);
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size = -EINVAL;
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}
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flush_dcache_page(p->page);
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if (size > 0)
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p->offset += size;
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return size;
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}
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static int
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lo_direct_splice_actor(struct pipe_inode_info *pipe, struct splice_desc *sd)
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{
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return __splice_from_pipe(pipe, sd, lo_splice_actor);
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}
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static ssize_t
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do_lo_receive(struct loop_device *lo,
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struct bio_vec *bvec, int bsize, loff_t pos)
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{
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struct lo_read_data cookie;
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struct splice_desc sd;
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struct file *file;
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ssize_t retval;
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cookie.lo = lo;
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cookie.page = bvec->bv_page;
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cookie.offset = bvec->bv_offset;
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cookie.bsize = bsize;
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sd.len = 0;
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sd.total_len = bvec->bv_len;
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sd.flags = 0;
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sd.pos = pos;
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sd.u.data = &cookie;
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file = lo->lo_backing_file;
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retval = splice_direct_to_actor(file, &sd, lo_direct_splice_actor);
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return retval;
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}
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static int
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lo_receive(struct loop_device *lo, struct request *rq, int bsize, loff_t pos)
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static int lo_read_simple(struct loop_device *lo, struct request *rq,
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loff_t pos)
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{
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struct bio_vec bvec;
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struct req_iterator iter;
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ssize_t s;
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struct iov_iter i;
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ssize_t len;
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rq_for_each_segment(bvec, rq, iter) {
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s = do_lo_receive(lo, &bvec, bsize, pos);
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if (s < 0)
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return s;
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iov_iter_bvec(&i, ITER_BVEC, &bvec, 1, bvec.bv_len);
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len = vfs_iter_read(lo->lo_backing_file, &i, &pos);
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if (len < 0)
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return len;
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if (s != bvec.bv_len) {
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flush_dcache_page(bvec.bv_page);
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if (len != bvec.bv_len) {
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struct bio *bio;
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__rq_for_each_bio(bio, rq)
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zero_fill_bio(bio);
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break;
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}
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pos += bvec.bv_len;
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cond_resched();
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}
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return 0;
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}
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static int lo_read_transfer(struct loop_device *lo, struct request *rq,
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loff_t pos)
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{
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struct bio_vec bvec, b;
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struct req_iterator iter;
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struct iov_iter i;
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struct page *page;
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ssize_t len;
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int ret = 0;
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page = alloc_page(GFP_NOIO);
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if (unlikely(!page))
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return -ENOMEM;
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rq_for_each_segment(bvec, rq, iter) {
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loff_t offset = pos;
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b.bv_page = page;
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b.bv_offset = 0;
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b.bv_len = bvec.bv_len;
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iov_iter_bvec(&i, ITER_BVEC, &b, 1, b.bv_len);
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len = vfs_iter_read(lo->lo_backing_file, &i, &pos);
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if (len < 0) {
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ret = len;
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goto out_free_page;
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}
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ret = lo_do_transfer(lo, READ, page, 0, bvec.bv_page,
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bvec.bv_offset, len, offset >> 9);
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if (ret)
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goto out_free_page;
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flush_dcache_page(bvec.bv_page);
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if (len != bvec.bv_len) {
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struct bio *bio;
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__rq_for_each_bio(bio, rq)
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zero_fill_bio(bio);
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break;
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}
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}
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ret = 0;
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out_free_page:
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__free_page(page);
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return ret;
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}
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static int lo_discard(struct loop_device *lo, struct request *rq, loff_t pos)
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{
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/*
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@ -464,10 +403,17 @@ static int do_req_filebacked(struct loop_device *lo, struct request *rq)
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ret = lo_req_flush(lo, rq);
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else if (rq->cmd_flags & REQ_DISCARD)
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ret = lo_discard(lo, rq, pos);
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else if (lo->transfer)
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ret = lo_write_transfer(lo, rq, pos);
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else
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ret = lo_send(lo, rq, pos);
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} else
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ret = lo_receive(lo, rq, lo->lo_blocksize, pos);
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ret = lo_write_simple(lo, rq, pos);
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} else {
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if (lo->transfer)
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ret = lo_read_transfer(lo, rq, pos);
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else
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ret = lo_read_simple(lo, rq, pos);
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}
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return ret;
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}
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@ -788,7 +734,7 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
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lo->lo_device = bdev;
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lo->lo_flags = lo_flags;
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lo->lo_backing_file = file;
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lo->transfer = transfer_none;
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lo->transfer = NULL;
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lo->ioctl = NULL;
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lo->lo_sizelimit = 0;
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lo->old_gfp_mask = mapping_gfp_mask(mapping);
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