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>

1 files changed, 120 insertions, 174 deletions

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index c4fd1e45ce1e..ae3fcb4199e9 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -88,28 +88,6 @@ static int part_shift;
 
 static struct workqueue_struct *loop_wq;
 
-/*
- * Transfer functions
- */
-static int transfer_none(struct loop_device *lo, int cmd,
-                         struct page *raw_page, unsigned raw_off,
-                         struct page *loop_page, unsigned loop_off,
-                         int size, sector_t real_block)
-{
-        char *raw_buf = kmap_atomic(raw_page) + raw_off;
-        char *loop_buf = kmap_atomic(loop_page) + loop_off;
-
-        if (cmd == READ)
-                memcpy(loop_buf, raw_buf, size);
-        else
-                memcpy(raw_buf, loop_buf, size);
-
-        kunmap_atomic(loop_buf);
-        kunmap_atomic(raw_buf);
-        cond_resched();
-        return 0;
-}
-
 static int transfer_xor(struct loop_device *lo, int cmd,
                         struct page *raw_page, unsigned raw_off,
                         struct page *loop_page, unsigned loop_off,
@@ -148,14 +126,13 @@ static int xor_init(struct loop_device *lo, const struct loop_info64 *info)
 
 static struct loop_func_table none_funcs = {
         .number = LO_CRYPT_NONE,
-        .transfer = transfer_none,
-};      
+}; 
 
 static struct loop_func_table xor_funcs = {
         .number = LO_CRYPT_XOR,
         .transfer = transfer_xor,
         .init = xor_init
-};      
+}; 
 
 /* xfer_funcs[0] is special - its release function is never called */
 static struct loop_func_table *xfer_funcs[MAX_LO_CRYPT] = {
@@ -215,207 +192,169 @@ lo_do_transfer(struct loop_device *lo, int cmd,
                struct page *lpage, unsigned loffs,
                int size, sector_t rblock)
 {
-        if (unlikely(!lo->transfer))
+        int ret;
+
+        ret = lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock);
+        if (likely(!ret))
                 return 0;
 
-        return lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock);
+        printk_ratelimited(KERN_ERR
+                "loop: Transfer error at byte offset %llu, length %i.\n",
+                (unsigned long long)rblock << 9, size);
+        return ret;
 }
 
-/**
- * __do_lo_send_write - helper for writing data to a loop device
- *
- * This helper just factors out common code between do_lo_send_direct_write()
- * and do_lo_send_write().
- */
-static int __do_lo_send_write(struct file *file,
-                u8 *buf, const int len, loff_t pos)
+static int lo_write_bvec(struct file *file, struct bio_vec *bvec, loff_t *ppos)
 {
-        struct kvec kvec = {.iov_base = buf, .iov_len = len};
-        struct iov_iter from;
+        struct iov_iter i;
         ssize_t bw;
 
-        iov_iter_kvec(&from, ITER_KVEC | WRITE, &kvec, 1, len);
+        iov_iter_bvec(&i, ITER_BVEC, bvec, 1, bvec->bv_len);
 
         file_start_write(file);
-        bw = vfs_iter_write(file, &from, &pos);
+        bw = vfs_iter_write(file, &i, ppos);
         file_end_write(file);
-        if (likely(bw == len))
+
+        if (likely(bw ==  bvec->bv_len))
                 return 0;
-        printk_ratelimited(KERN_ERR "loop: Write error at byte offset %llu, length %i.\n",
-                        (unsigned long long)pos, len);
+
+        printk_ratelimited(KERN_ERR
+                "loop: Write error at byte offset %llu, length %i.\n",
+                (unsigned long long)*ppos, bvec->bv_len);
         if (bw >= 0)
                 bw = -EIO;
         return bw;
 }
 
-/**
- * do_lo_send_direct_write - helper for writing data to a loop device
- *
- * This is the fast, non-transforming version that does not need double
- * buffering.
- */
-static int do_lo_send_direct_write(struct loop_device *lo,
-                struct bio_vec *bvec, loff_t pos, struct page *page)
+static int lo_write_simple(struct loop_device *lo, struct request *rq,
+                loff_t pos)
 {
-        ssize_t bw = __do_lo_send_write(lo->lo_backing_file,
-                        kmap(bvec->bv_page) + bvec->bv_offset,
-                        bvec->bv_len, pos);
-        kunmap(bvec->bv_page);
-        cond_resched();
-        return bw;
+        struct bio_vec bvec;
+        struct req_iterator iter;
+        int ret = 0;
+
+        rq_for_each_segment(bvec, rq, iter) {
+                ret = lo_write_bvec(lo->lo_backing_file, &bvec, &pos);
+                if (ret < 0)
+                        break;
+                cond_resched();
+        }
+
+        return ret;
 }
 
-/**
- * do_lo_send_write - helper for writing data to a loop device
- *
+/*
  * This is the slow, transforming version that needs to double buffer the
  * data as it cannot do the transformations in place without having direct
  * access to the destination pages of the backing file.
  */
-static int do_lo_send_write(struct loop_device *lo, struct bio_vec *bvec,
-                loff_t pos, struct page *page)
+static int lo_write_transfer(struct loop_device *lo, struct request *rq,
+                loff_t pos)
 {
-        int ret = lo_do_transfer(lo, WRITE, page, 0, bvec->bv_page,
-                        bvec->bv_offset, bvec->bv_len, pos >> 9);
-        if (likely(!ret))
-                return __do_lo_send_write(lo->lo_backing_file,
-                                page_address(page), bvec->bv_len,
-                                pos);
-        printk_ratelimited(KERN_ERR "loop: Transfer error at byte offset %llu, "
-                        "length %i.\n", (unsigned long long)pos, bvec->bv_len);
-        if (ret > 0)
-                ret = -EIO;
-        return ret;
-}
-
-static int lo_send(struct loop_device *lo, struct request *rq, loff_t pos)
-{
-        int (*do_lo_send)(struct loop_device *, struct bio_vec *, loff_t,
-                        struct page *page);
-        struct bio_vec bvec;
+        struct bio_vec bvec, b;
         struct req_iterator iter;
-        struct page *page = NULL;
+        struct page *page;
         int ret = 0;
 
-        if (lo->transfer != transfer_none) {
-                page = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
-                if (unlikely(!page))
-                        goto fail;
-                kmap(page);
-                do_lo_send = do_lo_send_write;
-        } else {
-                do_lo_send = do_lo_send_direct_write;
-        }
+        page = alloc_page(GFP_NOIO);
+        if (unlikely(!page))
+                return -ENOMEM;
 
         rq_for_each_segment(bvec, rq, iter) {
-                ret = do_lo_send(lo, &bvec, pos, page);
+                ret = lo_do_transfer(lo, WRITE, page, 0, bvec.bv_page,
+                        bvec.bv_offset, bvec.bv_len, pos >> 9);
+                if (unlikely(ret))
+                        break;
+
+                b.bv_page = page;
+                b.bv_offset = 0;
+                b.bv_len = bvec.bv_len;
+                ret = lo_write_bvec(lo->lo_backing_file, &b, &pos);
                 if (ret < 0)
                         break;
-                pos += bvec.bv_len;
         }
-        if (page) {
-                kunmap(page);
-                __free_page(page);
-        }
-out:
+
+        __free_page(page);
         return ret;
-fail:
-        printk_ratelimited(KERN_ERR "loop: Failed to allocate temporary page for write.\n");
-        ret = -ENOMEM;
-        goto out;
 }
 
-struct lo_read_data {
-        struct loop_device *lo;
-        struct page *page;
-        unsigned offset;
-        int bsize;
-};
+static int lo_read_simple(struct loop_device *lo, struct request *rq,
+                loff_t pos)
+{
+        struct bio_vec bvec;
+        struct req_iterator iter;
+        struct iov_iter i;
+        ssize_t len;
 
-static int
-lo_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
-                struct splice_desc *sd)
-{
-        struct lo_read_data *p = sd->u.data;
-        struct loop_device *lo = p->lo;
-        struct page *page = buf->page;
-        sector_t IV;
-        int size;
-
-        IV = ((sector_t) page->index << (PAGE_CACHE_SHIFT - 9)) +
-                                                        (buf->offset >> 9);
-        size = sd->len;
-        if (size > p->bsize)
-                size = p->bsize;
-
-        if (lo_do_transfer(lo, READ, page, buf->offset, p->page, p->offset, size, IV)) {
-                printk_ratelimited(KERN_ERR "loop: transfer error block %ld\n",
-                       page->index);
-                size = -EINVAL;
-        }
+        rq_for_each_segment(bvec, rq, iter) {
+                iov_iter_bvec(&i, ITER_BVEC, &bvec, 1, bvec.bv_len);
+                len = vfs_iter_read(lo->lo_backing_file, &i, &pos);
+                if (len < 0)
+                        return len;
 
-        flush_dcache_page(p->page);
+                flush_dcache_page(bvec.bv_page);
 
-        if (size > 0)
-                p->offset += size;
+                if (len != bvec.bv_len) {
+                        struct bio *bio;
 
-        return size;
-}
+                        __rq_for_each_bio(bio, rq)
+                                zero_fill_bio(bio);
+                        break;
+                }
+                cond_resched();
+        }
 
-static int
-lo_direct_splice_actor(struct pipe_inode_info *pipe, struct splice_desc *sd)
-{
-        return __splice_from_pipe(pipe, sd, lo_splice_actor);
+        return 0;
 }
 
-static ssize_t
-do_lo_receive(struct loop_device *lo,
-              struct bio_vec *bvec, int bsize, loff_t pos)
+static int lo_read_transfer(struct loop_device *lo, struct request *rq,
+                loff_t pos)
 {
-        struct lo_read_data cookie;
-        struct splice_desc sd;
-        struct file *file;
-        ssize_t retval;
+        struct bio_vec bvec, b;
+        struct req_iterator iter;
+        struct iov_iter i;
+        struct page *page;
+        ssize_t len;
+        int ret = 0;
 
-        cookie.lo = lo;
-        cookie.page = bvec->bv_page;
-        cookie.offset = bvec->bv_offset;
-        cookie.bsize = bsize;
+        page = alloc_page(GFP_NOIO);
+        if (unlikely(!page))
+                return -ENOMEM;
 
-        sd.len = 0;
-        sd.total_len = bvec->bv_len;
-        sd.flags = 0;
-        sd.pos = pos;
-        sd.u.data = &cookie;
+        rq_for_each_segment(bvec, rq, iter) {
+                loff_t offset = pos;
 
-        file = lo->lo_backing_file;
-        retval = splice_direct_to_actor(file, &sd, lo_direct_splice_actor);
+                b.bv_page = page;
+                b.bv_offset = 0;
+                b.bv_len = bvec.bv_len;
 
-        return retval;
-}
+                iov_iter_bvec(&i, ITER_BVEC, &b, 1, b.bv_len);
+                len = vfs_iter_read(lo->lo_backing_file, &i, &pos);
+                if (len < 0) {
+                        ret = len;
+                        goto out_free_page;
+                }
 
-static int
-lo_receive(struct loop_device *lo, struct request *rq, int bsize, loff_t pos)
-{
-        struct bio_vec bvec;
-        struct req_iterator iter;
-        ssize_t s;
+                ret = lo_do_transfer(lo, READ, page, 0, bvec.bv_page,
+                        bvec.bv_offset, len, offset >> 9);
+                if (ret)
+                        goto out_free_page;
 
-        rq_for_each_segment(bvec, rq, iter) {
-                s = do_lo_receive(lo, &bvec, bsize, pos);
-                if (s < 0)
-                        return s;
+                flush_dcache_page(bvec.bv_page);
 
-                if (s != bvec.bv_len) {
+                if (len != bvec.bv_len) {
                         struct bio *bio;
 
                         __rq_for_each_bio(bio, rq)
                                 zero_fill_bio(bio);
                         break;
                 }
-                pos += bvec.bv_len;
         }
-        return 0;
+
+        ret = 0;
+out_free_page:
+        __free_page(page);
+        return ret;
 }
 
 static int lo_discard(struct loop_device *lo, struct request *rq, loff_t pos)
@@ -464,10 +403,17 @@ static int do_req_filebacked(struct loop_device *lo, struct request *rq)
                         ret = lo_req_flush(lo, rq);
                 else if (rq->cmd_flags & REQ_DISCARD)
                         ret = lo_discard(lo, rq, pos);
+                else if (lo->transfer)
+                        ret = lo_write_transfer(lo, rq, pos);
                 else
-                        ret = lo_send(lo, rq, pos);
-        } else
-                ret = lo_receive(lo, rq, lo->lo_blocksize, pos);
+                        ret = lo_write_simple(lo, rq, pos);
+
+        } else {
+                if (lo->transfer)
+                        ret = lo_read_transfer(lo, rq, pos);
+                else
+                        ret = lo_read_simple(lo, rq, pos);
+        }
 
         return ret;
 }
@@ -788,7 +734,7 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
         lo->lo_device = bdev;
         lo->lo_flags = lo_flags;
         lo->lo_backing_file = file;
-        lo->transfer = transfer_none;
+        lo->transfer = NULL;
         lo->ioctl = NULL;
         lo->lo_sizelimit = 0;
         lo->old_gfp_mask = mapping_gfp_mask(mapping);
@@ -1007,7 +953,7 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
                 memcpy(lo->lo_encrypt_key, info->lo_encrypt_key,
                        info->lo_encrypt_key_size);
                 lo->lo_key_owner = uid;
-        }       
+        }
 
         return 0;
 }