2 files changed, 23 insertions, 113 deletions

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 4720c7ade0ae..46cdd6945557 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -203,74 +203,6 @@ lo_do_transfer(struct loop_device *lo, int cmd,
 }
 
 /**
- * do_lo_send_aops - helper for writing data to a loop device
- *
- * This is the fast version for backing filesystems which implement the address
- * space operations write_begin and write_end.
- */
-static int do_lo_send_aops(struct loop_device *lo, struct bio_vec *bvec,
-                loff_t pos, struct page *unused)
-{
-        struct file *file = lo->lo_backing_file; /* kudos to NFsckingS */
-        struct address_space *mapping = file->f_mapping;
-        pgoff_t index;
-        unsigned offset, bv_offs;
-        int len, ret;
-
-        mutex_lock(&mapping->host->i_mutex);
-        index = pos >> PAGE_CACHE_SHIFT;
-        offset = pos & ((pgoff_t)PAGE_CACHE_SIZE - 1);
-        bv_offs = bvec->bv_offset;
-        len = bvec->bv_len;
-        while (len > 0) {
-                sector_t IV;
-                unsigned size, copied;
-                int transfer_result;
-                struct page *page;
-                void *fsdata;
-
-                IV = ((sector_t)index << (PAGE_CACHE_SHIFT - 9))+(offset >> 9);
-                size = PAGE_CACHE_SIZE - offset;
-                if (size > len)
-                        size = len;
-
-                ret = pagecache_write_begin(file, mapping, pos, size, 0,
-                                                        &page, &fsdata);
-                if (ret)
-                        goto fail;
-
-                file_update_time(file);
-
-                transfer_result = lo_do_transfer(lo, WRITE, page, offset,
-                                bvec->bv_page, bv_offs, size, IV);
-                copied = size;
-                if (unlikely(transfer_result))
-                        copied = 0;
-
-                ret = pagecache_write_end(file, mapping, pos, size, copied,
-                                                        page, fsdata);
-                if (ret < 0 || ret != copied)
-                        goto fail;
-
-                if (unlikely(transfer_result))
-                        goto fail;
-
-                bv_offs += copied;
-                len -= copied;
-                offset = 0;
-                index++;
-                pos += copied;
-        }
-        ret = 0;
-out:
-        mutex_unlock(&mapping->host->i_mutex);
-        return ret;
-fail:
-        ret = -1;
-        goto out;
-}
-
-/**
  * __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()
@@ -297,10 +229,8 @@ static int __do_lo_send_write(struct file *file,
 /**
  * do_lo_send_direct_write - helper for writing data to a loop device
  *
- * This is the fast, non-transforming version for backing filesystems which do
- * not implement the address space operations write_begin and write_end.
- * It uses the write file operation which should be present on all writeable
- * filesystems.
+ * 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)
@@ -316,15 +246,9 @@ static int do_lo_send_direct_write(struct loop_device *lo,
 /**
  * do_lo_send_write - helper for writing data to a loop device
  *
- * This is the slow, transforming version for filesystems which do not
- * implement the address space operations write_begin and write_end.  It
- * uses the write file operation which should be present on all writeable
- * filesystems.
- *
- * Using fops->write is slower than using aops->{prepare,commit}_write in the
- * transforming case because we need to double buffer the data as we cannot do
- * the transformations in place as we do not have direct access to the
- * destination pages of the backing file.
+ * 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)
@@ -350,17 +274,16 @@ static int lo_send(struct loop_device *lo, struct bio *bio, loff_t pos)
         struct page *page = NULL;
         int i, ret = 0;
 
-        do_lo_send = do_lo_send_aops;
-        if (!(lo->lo_flags & LO_FLAGS_USE_AOPS)) {
+        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;
-                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;
-                }
         }
+
         bio_for_each_segment(bvec, bio, i) {
                 ret = do_lo_send(lo, bvec, pos, page);
                 if (ret < 0)
@@ -849,35 +772,23 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
         mapping = file->f_mapping;
         inode = mapping->host;
 
-        if (!(file->f_mode & FMODE_WRITE))
-                lo_flags |= LO_FLAGS_READ_ONLY;
-
         error = -EINVAL;
-        if (S_ISREG(inode->i_mode) || S_ISBLK(inode->i_mode)) {
-                const struct address_space_operations *aops = mapping->a_ops;
-
-                if (aops->write_begin)
-                        lo_flags |= LO_FLAGS_USE_AOPS;
-                if (!(lo_flags & LO_FLAGS_USE_AOPS) && !file->f_op->write)
-                        lo_flags |= LO_FLAGS_READ_ONLY;
+        if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
+                goto out_putf;
 
-                lo_blocksize = S_ISBLK(inode->i_mode) ?
-                        inode->i_bdev->bd_block_size : PAGE_SIZE;
+        if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) ||
+            !file->f_op->write)
+                lo_flags |= LO_FLAGS_READ_ONLY;
 
-                error = 0;
-        } else {
-                goto out_putf;
-        }
+        lo_blocksize = S_ISBLK(inode->i_mode) ?
+                inode->i_bdev->bd_block_size : PAGE_SIZE;
 
+        error = -EFBIG;
         size = get_loop_size(lo, file);
-
-        if ((loff_t)(sector_t)size != size) {
-                error = -EFBIG;
+        if ((loff_t)(sector_t)size != size)
                 goto out_putf;
-        }
 
-        if (!(mode & FMODE_WRITE))
-                lo_flags |= LO_FLAGS_READ_ONLY;
+        error = 0;
 
         set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0);
 
diff --git a/include/linux/loop.h b/include/linux/loop.h
index 683d69890119..a06880689115 100644
--- a/include/linux/loop.h
+++ b/include/linux/loop.h
@@ -73,7 +73,6 @@ struct loop_device {
  */
 enum {
         LO_FLAGS_READ_ONLY      = 1,
-        LO_FLAGS_USE_AOPS       = 2,
         LO_FLAGS_AUTOCLEAR      = 4,
 };