ext4: move_extent improve bh vanishing success factor (88c6b61f) · Commits · 戴 / test

Xiaoguang Wang has reported sporadic EBUSY failures of ext4/302 Unfortunetly there is nothing we can do if some other task holds BH's refenrence. So we must return EBUSY in this case. But we can try kicking the journal to see if the other task releases the bh reference after the commit is complete. Also decrease false positives by properly checking for ENOSPC and retrying the allocation after kicking the journal --- which is done by ext4_should_retry_alloc(). [ Modified by tytso to properly check for ENOSPC. ] Signed-off-by:

Dmitry Monakhov <dmonakhov@openvz.org> Signed-off-by:

Theodore Ts'o <tytso@mit.edu>

fs/ext4/move_extent.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -273,6 +273,7 @@ move_extent_per_page(struct file o_filp, struct inode donor_inode,
		int replaced_count = 0;
		int from = data_offset_in_page << orig_inode->i_blkbits;
		int blocks_per_page = PAGE_CACHE_SIZE >> orig_inode->i_blkbits;
		struct super_block *sb = orig_inode->i_sb;

		/*
		* It needs twice the amount of ordinary journal buffers because
		@@ -405,10 +406,13 @@ unlock_pages:
		page_cache_release(pagep[1]);
		stop_journal:
		ext4_journal_stop(handle);
		if (*err == -ENOSPC &&
		ext4_should_retry_alloc(sb, &retries))
		goto again;
		/* Buffer was busy because probably is pinned to journal transaction,
		* force transaction commit may help to free it. */
		if (*err == -EBUSY && ext4_should_retry_alloc(orig_inode->i_sb,
		&retries))
		if (*err == -EBUSY && retries++ < 4 && EXT4_SB(sb)->s_journal &&
		jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal))
		goto again;
		return replaced_count;

Admin message