diff --git a/include/linux/fs.h b/include/linux/fs.h
index 98e0349adb52..092ea2a4319b 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -314,6 +314,7 @@ enum rw_hint {
 #define IOCB_SYNC		(1 << 5)
 #define IOCB_WRITE		(1 << 6)
 #define IOCB_NOWAIT		(1 << 7)
+#define IOCB_UNCACHED		(1 << 8)
 
 struct kiocb {
 	struct file		*ki_filp;
@@ -3418,6 +3419,8 @@ static inline int kiocb_set_rw_flags(struct kiocb *ki, rwf_t flags)
 		ki->ki_flags |= (IOCB_DSYNC | IOCB_SYNC);
 	if (flags & RWF_APPEND)
 		ki->ki_flags |= IOCB_APPEND;
+	if (flags & RWF_UNCACHED)
+		ki->ki_flags |= IOCB_UNCACHED;
 	return 0;
 }
 
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index 379a612f8f1d..357ebb0e0c5d 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -299,8 +299,11 @@ typedef int __bitwise __kernel_rwf_t;
 /* per-IO O_APPEND */
 #define RWF_APPEND	((__force __kernel_rwf_t)0x00000010)
 
+/* drop cache after reading or writing data */
+#define RWF_UNCACHED	((__force __kernel_rwf_t)0x00000040)
+
 /* mask of flags supported by the kernel */
 #define RWF_SUPPORTED	(RWF_HIPRI | RWF_DSYNC | RWF_SYNC | RWF_NOWAIT |\
-			 RWF_APPEND)
+			 RWF_APPEND | RWF_UNCACHED)
 
 #endif /* _UAPI_LINUX_FS_H */
diff --git a/mm/filemap.c b/mm/filemap.c
index bf6aa30be58d..7ddc4d8386cf 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1990,6 +1990,13 @@ static void shrink_readahead_size_eio(struct file *filp,
 	ra->ra_pages /= 4;
 }
 
+static void buffered_put_page(struct page *page, bool clear_mapping)
+{
+	if (clear_mapping)
+		page->mapping = NULL;
+	put_page(page);
+}
+
 /**
  * generic_file_buffered_read - generic file read routine
  * @iocb:	the iocb to read
@@ -2013,6 +2020,7 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb,
 	struct address_space *mapping = filp->f_mapping;
 	struct inode *inode = mapping->host;
 	struct file_ra_state *ra = &filp->f_ra;
+	bool did_dio_begin = false;
 	loff_t *ppos = &iocb->ki_pos;
 	pgoff_t index;
 	pgoff_t last_index;
@@ -2032,6 +2040,7 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb,
 	offset = *ppos & ~PAGE_MASK;
 
 	for (;;) {
+		bool clear_mapping = false;
 		struct page *page;
 		pgoff_t end_index;
 		loff_t isize;
@@ -2048,6 +2057,13 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb,
 		if (!page) {
 			if (iocb->ki_flags & IOCB_NOWAIT)
 				goto would_block;
+			/* UNCACHED implies no read-ahead */
+			if (iocb->ki_flags & IOCB_UNCACHED) {
+				did_dio_begin = true;
+				/* block truncate for UNCACHED reads */
+				inode_dio_begin(inode);
+				goto no_cached_page;
+			}
 			page_cache_sync_readahead(mapping,
 					ra, filp,
 					index, last_index - index);
@@ -2106,7 +2122,7 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb,
 		isize = i_size_read(inode);
 		end_index = (isize - 1) >> PAGE_SHIFT;
 		if (unlikely(!isize || index > end_index)) {
-			put_page(page);
+			buffered_put_page(page, clear_mapping);
 			goto out;
 		}
 
@@ -2115,7 +2131,7 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb,
 		if (index == end_index) {
 			nr = ((isize - 1) & ~PAGE_MASK) + 1;
 			if (nr <= offset) {
-				put_page(page);
+				buffered_put_page(page, clear_mapping);
 				goto out;
 			}
 		}
@@ -2147,7 +2163,7 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb,
 		offset &= ~PAGE_MASK;
 		prev_offset = offset;
 
-		put_page(page);
+		buffered_put_page(page, clear_mapping);
 		written += ret;
 		if (!iov_iter_count(iter))
 			goto out;
@@ -2189,7 +2205,7 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb,
 
 		if (unlikely(error)) {
 			if (error == AOP_TRUNCATED_PAGE) {
-				put_page(page);
+				buffered_put_page(page, clear_mapping);
 				error = 0;
 				goto find_page;
 			}
@@ -2206,7 +2222,7 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb,
 					 * invalidate_mapping_pages got it
 					 */
 					unlock_page(page);
-					put_page(page);
+					buffered_put_page(page, clear_mapping);
 					goto find_page;
 				}
 				unlock_page(page);
@@ -2221,7 +2237,7 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb,
 
 readpage_error:
 		/* UHHUH! A synchronous read error occurred. Report it */
-		put_page(page);
+		buffered_put_page(page, clear_mapping);
 		goto out;
 
 no_cached_page:
@@ -2234,6 +2250,14 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb,
 			error = -ENOMEM;
 			goto out;
 		}
+		if (iocb->ki_flags & IOCB_UNCACHED) {
+			__SetPageLocked(page);
+			page->mapping = mapping;
+			page->index = index;
+			clear_mapping = true;
+			goto readpage;
+		}
+
 		error = add_to_page_cache_lru(page, mapping, index,
 				mapping_gfp_constraint(mapping, GFP_KERNEL));
 		if (error) {
@@ -2250,6 +2274,8 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb,
 would_block:
 	error = -EAGAIN;
 out:
+	if (did_dio_begin)
+		inode_dio_end(inode);
 	ra->prev_pos = prev_index;
 	ra->prev_pos <<= PAGE_SHIFT;
 	ra->prev_pos |= prev_offset;
