diff --git a/common/block.c b/common/block.c
index 97cf5dc..02be80d 100644
--- a/common/block.c
+++ b/common/block.c
@@ -36,7 +36,7 @@
 	struct list_head list;
 };
 
-#define BUFSIZE (PAGE_SIZE * 4)
+#define BUFSIZE (PAGE_SIZE * 16)
 
 static int writebuffer_io_len(struct block_device *blk, struct chunk *chunk)
 {
@@ -161,6 +161,14 @@
 	dev_dbg(blk->dev, "%s: %d to %d\n", __func__, chunk->block_start,
 		chunk->num);
 
+	if (chunk->block_start * BLOCKSIZE(blk) >= blk->discard_start &&
+	    chunk->block_start * BLOCKSIZE(blk) + writebuffer_io_len(blk, chunk)
+	    <= blk->discard_start + blk->discard_size) {
+		memset(chunk->data, 0, writebuffer_io_len(blk, chunk));
+		list_add(&chunk->list, &blk->buffered_blocks);
+		return 0;
+	}
+
 	ret = blk->ops->read(blk, chunk->data, chunk->block_start,
 			     writebuffer_io_len(blk, chunk));
 	if (ret) {
@@ -337,11 +345,23 @@
 {
 	struct block_device *blk = cdev->priv;
 
+	blk->discard_start = blk->discard_size = 0;
+
 	return writebuffer_flush(blk);
 }
 
 static int block_op_close(struct cdev *cdev) __alias(block_op_flush);
 
+static int block_op_discard_range(struct cdev *cdev, loff_t count, loff_t offset)
+{
+	struct block_device *blk = cdev->priv;
+
+	blk->discard_start = offset;
+	blk->discard_size = count;
+
+	return 0;
+}
+
 static struct cdev_operations block_ops = {
 	.read	= block_op_read,
 #ifdef CONFIG_BLOCK_WRITE
@@ -349,6 +369,7 @@
 #endif
 	.close	= block_op_close,
 	.flush	= block_op_flush,
+	.discard_range = block_op_discard_range,
 };
 
 int blockdevice_register(struct block_device *blk)
@@ -370,7 +391,7 @@
 	dev_dbg(blk->dev, "rdbufsize: %d blockbits: %d blkmask: 0x%08x\n",
 		blk->rdbufsize, blk->blockbits, blk->blkmask);
 
-	for (i = 0; i < 32; i++) {
+	for (i = 0; i < 8; i++) {
 		struct chunk *chunk = xzalloc(sizeof(*chunk));
 		chunk->data = dma_alloc(BUFSIZE);
 		chunk->num = i;
diff --git a/drivers/usb/gadget/f_fastboot.c b/drivers/usb/gadget/f_fastboot.c
index 0a3aff3..426ee9d 100644
--- a/drivers/usb/gadget/f_fastboot.c
+++ b/drivers/usb/gadget/f_fastboot.c
@@ -957,6 +957,8 @@
 			if (ret)
 				goto out;
 		} else {
+			discard_range(fd, retlen, pos);
+
 			pos = lseek(fd, pos, SEEK_SET);
 			if (pos == -1) {
 				ret = -errno;
diff --git a/fs/devfs.c b/fs/devfs.c
index d088c1a..e1893d1 100644
--- a/fs/devfs.c
+++ b/fs/devfs.c
@@ -94,6 +94,26 @@
 	return cdev->ops->protect(cdev, count, offset + cdev->offset, prot);
 }
 
+static int devfs_discard_range(struct device_d *dev, FILE *f, loff_t count,
+			       loff_t offset)
+{
+	struct cdev *cdev = f->priv;
+
+	if (!cdev->ops->discard_range)
+		return -ENOSYS;
+
+	if (cdev->flags & DEVFS_PARTITION_READONLY)
+		return -EPERM;
+
+	if (offset >= cdev->size)
+		return 0;
+
+	if (count + offset > cdev->size)
+		count = cdev->size - offset;
+
+	return cdev->ops->discard_range(cdev, count, offset + cdev->offset);
+}
+
 static int devfs_memmap(struct device_d *_dev, FILE *f, void **map, int flags)
 {
 	struct cdev *cdev = f->priv;
@@ -329,6 +349,7 @@
 	.truncate  = devfs_truncate,
 	.erase     = devfs_erase,
 	.protect   = devfs_protect,
+	.discard_range = devfs_discard_range,
 	.memmap    = devfs_memmap,
 	.flags     = FS_DRIVER_NO_DEV,
 	.drv = {
diff --git a/fs/fs.c b/fs/fs.c
index 12faaeb..e00bbcd 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -497,6 +497,31 @@
 }
 EXPORT_SYMBOL(protect);
 
+int discard_range(int fd, loff_t count, loff_t offset)
+{
+	struct fs_driver_d *fsdrv;
+	FILE *f = fd_to_file(fd);
+	int ret;
+
+	if (IS_ERR(f))
+		return -errno;
+	if (offset >= f->size)
+		return 0;
+	if (count > f->size - offset)
+		count = f->size - offset;
+
+	fsdrv = f->fsdev->driver;
+	if (fsdrv->discard_range)
+		ret = fsdrv->discard_range(&f->fsdev->dev, f, count, offset);
+	else
+		ret = -ENOSYS;
+
+	if (ret)
+		errno = -ret;
+
+	return ret;
+}
+
 int protect_file(const char *file, int prot)
 {
 	int fd, ret;
diff --git a/include/block.h b/include/block.h
index bd87efd..a1de266 100644
--- a/include/block.h
+++ b/include/block.h
@@ -24,6 +24,9 @@
 	int rdbufsize;
 	int blkmask;
 
+	loff_t discard_start;
+	loff_t discard_size;
+
 	struct list_head buffered_blocks;
 	struct list_head idle_blocks;
 
diff --git a/include/driver.h b/include/driver.h
index 6176e6a..fac3953 100644
--- a/include/driver.h
+++ b/include/driver.h
@@ -431,6 +431,7 @@
 	int (*flush)(struct cdev*);
 	int (*erase)(struct cdev*, loff_t count, loff_t offset);
 	int (*protect)(struct cdev*, size_t count, loff_t offset, int prot);
+	int (*discard_range)(struct cdev*, loff_t count, loff_t offset);
 	int (*memmap)(struct cdev*, void **map, int flags);
 	int (*truncate)(struct cdev*, size_t size);
 };
diff --git a/include/fs.h b/include/fs.h
index 04ec132..5811199 100644
--- a/include/fs.h
+++ b/include/fs.h
@@ -61,6 +61,8 @@
 			loff_t offset);
 	int (*protect)(struct device_d *dev, FILE *f, size_t count,
 			loff_t offset, int prot);
+	int (*discard_range)(struct device_d *dev, FILE *f, loff_t count,
+			loff_t offset);
 
 	int (*memmap)(struct device_d *dev, FILE *f, void **map, int flags);
 
@@ -128,6 +130,7 @@
 #define ERASE_SIZE_ALL	((loff_t) - 1)
 int erase(int fd, loff_t count, loff_t offset);
 int protect(int fd, size_t count, loff_t offset, int prot);
+int discard_range(int fd, loff_t count, loff_t offset);
 int protect_file(const char *file, int prot);
 void *memmap(int fd, int flags);
 
diff --git a/lib/libfile.c b/lib/libfile.c
index 5a1817e..dbeed12 100644
--- a/lib/libfile.c
+++ b/lib/libfile.c
@@ -367,6 +367,8 @@
 		goto out;
 	}
 
+	discard_range(dstfd, srcstat.st_size, 0);
+
 	if (verbose) {
 		if (stat(src, &srcstat) < 0)
 			srcstat.st_size = 0;