ext4: remove vestiges of nobh support

The nobh option was only supported for writeback mode, but given that all
write paths actually create buffer heads it effectively was a no-op already.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/ext4.h

@@ -873,7 +873,6 @@ struct ext4_inode_info {
 #define EXT4_MOUNT_POSIX_ACL		0x08000	/* POSIX Access Control Lists */
 #define EXT4_MOUNT_NO_AUTO_DA_ALLOC	0x10000	/* No auto delalloc mapping */
 #define EXT4_MOUNT_BARRIER		0x20000 /* Use block barriers */
-#define EXT4_MOUNT_NOBH			0x40000 /* No bufferheads */
 #define EXT4_MOUNT_QUOTA		0x80000 /* Some quota option set */
 #define EXT4_MOUNT_USRQUOTA		0x100000 /* "old" user quota */
 #define EXT4_MOUNT_GRPQUOTA		0x200000 /* "old" group quota */

fs/ext4/ext4_jbd2.h

@@ -313,17 +313,15 @@ static inline int ext4_should_writeback_data(struct inode *inode)
  * This function controls whether or not we should try to go down the
  * dioread_nolock code paths, which makes it safe to avoid taking
  * i_mutex for direct I/O reads.  This only works for extent-based
- * files, and it doesn't work for nobh or if data journaling is
- * enabled, since the dioread_nolock code uses b_private to pass
- * information back to the I/O completion handler, and this conflicts
- * with the jbd's use of b_private.
+ * files, and it doesn't work if data journaling is enabled, since the
+ * dioread_nolock code uses b_private to pass information back to the
+ * I/O completion handler, and this conflicts with the jbd's use of
+ * b_private.
  */
 static inline int ext4_should_dioread_nolock(struct inode *inode)
 {
 	if (!test_opt(inode->i_sb, DIOREAD_NOLOCK))
 		return 0;
-	if (test_opt(inode->i_sb, NOBH))
-		return 0;
 	if (!S_ISREG(inode->i_mode))
 		return 0;
 	if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))

fs/ext4/inode.c

@@ -2553,18 +2553,16 @@ static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
 /*
  * This function is used as a standard get_block_t calback function
  * when there is no desire to allocate any blocks.  It is used as a
- * callback function for block_prepare_write(), nobh_writepage(), and
- * block_write_full_page().  These functions should only try to map a
- * single block at a time.
+ * callback function for block_prepare_write() and block_write_full_page().
+ * These functions should only try to map a single block at a time.
  *
  * Since this function doesn't do block allocations even if the caller
  * requests it by passing in create=1, it is critically important that
  * any caller checks to make sure that any buffer heads are returned
  * by this function are either all already mapped or marked for
- * delayed allocation before calling nobh_writepage() or
- * block_write_full_page().  Otherwise, b_blocknr could be left
- * unitialized, and the page write functions will be taken by
- * surprise.
+ * delayed allocation before calling  block_write_full_page().  Otherwise,
+ * b_blocknr could be left unitialized, and the page write functions will
+ * be taken by surprise.
  */
 static int noalloc_get_block_write(struct inode *inode, sector_t iblock,
 				   struct buffer_head *bh_result, int create)
@@ -2749,9 +2747,7 @@ static int ext4_writepage(struct page *page,
 		return __ext4_journalled_writepage(page, len);
 	}
 
-	if (test_opt(inode->i_sb, NOBH) && ext4_should_writeback_data(inode))
-		ret = nobh_writepage(page, noalloc_get_block_write, wbc);
-	else if (page_bufs && buffer_uninit(page_bufs)) {
+	if (page_bufs && buffer_uninit(page_bufs)) {
 		ext4_set_bh_endio(page_bufs, inode);
 		ret = block_write_full_page_endio(page, noalloc_get_block_write,
 					    wbc, ext4_end_io_buffer_write);
@@ -4125,17 +4121,6 @@ int ext4_block_truncate_page(handle_t *handle,
 	length = blocksize - (offset & (blocksize - 1));
 	iblock = index << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
 
-	/*
-	 * For "nobh" option,  we can only work if we don't need to
-	 * read-in the page - otherwise we create buffers to do the IO.
-	 */
-	if (!page_has_buffers(page) && test_opt(inode->i_sb, NOBH) &&
-	     ext4_should_writeback_data(inode) && PageUptodate(page)) {
-		zero_user(page, offset, length);
-		set_page_dirty(page);
-		goto unlock;
-	}
-
 	if (!page_has_buffers(page))
 		create_empty_buffers(page, blocksize, 0);
 

fs/ext4/super.c

@@ -946,8 +946,6 @@ static int ext4_show_options(struct seq_file *seq, struct vfsmount *vfs)
 		seq_puts(seq, ",journal_async_commit");
 	else if (test_opt(sb, JOURNAL_CHECKSUM))
 		seq_puts(seq, ",journal_checksum");
-	if (test_opt(sb, NOBH))
-		seq_puts(seq, ",nobh");
 	if (test_opt(sb, I_VERSION))
 		seq_puts(seq, ",i_version");
 	if (!test_opt(sb, DELALLOC))
@@ -1624,10 +1622,12 @@ set_qf_format:
 			*n_blocks_count = option;
 			break;
 		case Opt_nobh:
-			set_opt(sbi->s_mount_opt, NOBH);
+			ext4_msg(sb, KERN_WARNING,
+				 "Ignoring deprecated nobh option");
 			break;
 		case Opt_bh:
-			clear_opt(sbi->s_mount_opt, NOBH);
+			ext4_msg(sb, KERN_WARNING,
+				 "Ignoring deprecated bh option");
 			break;
 		case Opt_i_version:
 			set_opt(sbi->s_mount_opt, I_VERSION);
@@ -2912,18 +2912,7 @@ no_journal:
 		ext4_msg(sb, KERN_ERR, "insufficient memory");
 		goto failed_mount_wq;
 	}
-	if (test_opt(sb, NOBH)) {
-		if (!(test_opt(sb, DATA_FLAGS) == EXT4_MOUNT_WRITEBACK_DATA)) {
-			ext4_msg(sb, KERN_WARNING, "Ignoring nobh option - "
-				"its supported only with writeback mode");
-			clear_opt(sbi->s_mount_opt, NOBH);
-		}
-		if (test_opt(sb, DIOREAD_NOLOCK)) {
-			ext4_msg(sb, KERN_WARNING, "dioread_nolock option is "
-				"not supported with nobh mode");
-			goto failed_mount_wq;
-		}
-	}
+
 	EXT4_SB(sb)->dio_unwritten_wq = create_workqueue("ext4-dio-unwritten");
 	if (!EXT4_SB(sb)->dio_unwritten_wq) {
 		printk(KERN_ERR "EXT4-fs: failed to create DIO workqueue\n");