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Commit a115f749 authored Jun 04, 2013 by Jan Kara Committed by Theodore Ts'o Jun 04, 2013

ext4: remove wait for unwritten extent conversion from ext4_truncate()



Since PageWriteback bit is now cleared after extents are converted
from unwritten to written ones, we have full exclusion of writeback
path from truncate (truncate_inode_pages() waits for PageWriteback
bits to get cleared on all invalidated pages).  Exclusion from DIO
path is achieved by inode_dio_wait() call in ext4_setattr().  So
there's no need to wait for extent convertion in ext4_truncate()
anymore.

Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

parent e8340395

fs/ext4/inode.c

+0 −6

Original line number	Diff line number	Diff line
		@@ -3643,12 +3643,6 @@ void ext4_truncate(struct inode *inode)
		return;
		}

		/*
		* finish any pending end_io work so we won't run the risk of
		* converting any truncated blocks to initialized later
		*/
		ext4_flush_unwritten_io(inode);

		if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
		credits = ext4_writepage_trans_blocks(inode);
		else

fs/ext4/page-io.c

+8 −1

Original line number	Diff line number	Diff line
		@@ -158,7 +158,14 @@ static void ext4_clear_io_unwritten_flag(ext4_io_end_t *io_end)
		wake_up_all(ext4_ioend_wq(inode));
		}

		/* check a range of space and convert unwritten extents to written. */
		/*
		* Check a range of space and convert unwritten extents to written. Note that
		* we are protected from truncate touching same part of extent tree by the
		* fact that truncate code waits for all DIO to finish (thus exclusion from
		* direct IO is achieved) and also waits for PageWriteback bits. Thus we
		* cannot get to ext4_ext_truncate() before all IOs overlapping that range are
		* completed (happens from ext4_free_ioend()).
		*/
		static int ext4_end_io(ext4_io_end_t *io)
		{
		struct inode *inode = io->inode;