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Commit 17335dcc authored by Dmitry Monakhov's avatar Dmitry Monakhov Committed by Theodore Ts'o
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ext4: serialize dio nonlocked reads with defrag workers 



Inode's block defrag and ext4_change_inode_journal_flag() may
affect nonlocked DIO reads result, so proper synchronization
required.

- Add missed inode_dio_wait() calls where appropriate
- Check inode state under extra i_dio_count reference.

Reviewed-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarDmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 28a535f9

fs/ext4/ext4.h

+17 −0
Original line number Diff line number Diff line
@@ -1358,6 +1358,8 @@ enum { 
	EXT4_STATE_DIO_UNWRITTEN,	/* need convert on dio done*/

	EXT4_STATE_NEWENTRY,		/* File just added to dir */

	EXT4_STATE_DELALLOC_RESERVED,	/* blks already reserved for delalloc */

	EXT4_STATE_DIOREAD_LOCK,	/* Disable support for dio read

					   nolocking */

};



#define EXT4_INODE_BIT_FNS(name, field, offset)				\
@@ -2469,6 +2471,21 @@ static inline void set_bitmap_uptodate(struct buffer_head *bh) 
	set_bit(BH_BITMAP_UPTODATE, &(bh)->b_state);

}



/*

 * Disable DIO read nolock optimization, so new dioreaders will be forced

 * to grab i_mutex

 */

static inline void ext4_inode_block_unlocked_dio(struct inode *inode)

{

	ext4_set_inode_state(inode, EXT4_STATE_DIOREAD_LOCK);

	smp_mb();

}

static inline void ext4_inode_resume_unlocked_dio(struct inode *inode)

{

	smp_mb();

	ext4_clear_inode_state(inode, EXT4_STATE_DIOREAD_LOCK);

}



#define in_range(b, first, len)	((b) >= (first) && (b) <= (first) + (len) - 1)



/* For ioend & aio unwritten conversion wait queues */

fs/ext4/indirect.c

+14 −0
Original line number Diff line number Diff line
@@ -810,11 +810,25 @@ retry: 
		if (unlikely(!list_empty(&ei->i_completed_io_list)))

			ext4_flush_completed_IO(inode);



		/*

		 * Nolock dioread optimization may be dynamically disabled

		 * via ext4_inode_block_unlocked_dio(). Check inode's state

		 * while holding extra i_dio_count ref.

		 */

		atomic_inc(&inode->i_dio_count);

		smp_mb();

		if (unlikely(ext4_test_inode_state(inode,

						    EXT4_STATE_DIOREAD_LOCK))) {

			inode_dio_done(inode);

			goto locked;

		}

		ret = __blockdev_direct_IO(rw, iocb, inode,

				 inode->i_sb->s_bdev, iov,

				 offset, nr_segs,

				 ext4_get_block, NULL, NULL, 0);

		inode_dio_done(inode);

	} else {

locked:

		ret = blockdev_direct_IO(rw, iocb, inode, iov,

				 offset, nr_segs, ext4_get_block);

fs/ext4/inode.c

+5 −0
Original line number Diff line number Diff line
@@ -4720,6 +4720,10 @@ int ext4_change_inode_journal_flag(struct inode *inode, int val) 
			return err;

	}



	/* Wait for all existing dio workers */

	ext4_inode_block_unlocked_dio(inode);

	inode_dio_wait(inode);



	jbd2_journal_lock_updates(journal);



	/*
@@ -4739,6 +4743,7 @@ int ext4_change_inode_journal_flag(struct inode *inode, int val) 
	ext4_set_aops(inode);



	jbd2_journal_unlock_updates(journal);

	ext4_inode_resume_unlocked_dio(inode);



	/* Finally we can mark the inode as dirty. */

fs/ext4/move_extent.c

+8 −0
Original line number Diff line number Diff line
@@ -1323,6 +1323,12 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, 
	/* Protect orig and donor inodes against a truncate */

	mext_inode_double_lock(orig_inode, donor_inode);



	/* Wait for all existing dio workers */

	ext4_inode_block_unlocked_dio(orig_inode);

	ext4_inode_block_unlocked_dio(donor_inode);

	inode_dio_wait(orig_inode);

	inode_dio_wait(donor_inode);



	/* Protect extent tree against block allocations via delalloc */

	double_down_write_data_sem(orig_inode, donor_inode);

	/* Check the filesystem environment whether move_extent can be done */
@@ -1521,6 +1527,8 @@ out: 
		kfree(holecheck_path);

	}

	double_up_write_data_sem(orig_inode, donor_inode);

	ext4_inode_resume_unlocked_dio(orig_inode);

	ext4_inode_resume_unlocked_dio(donor_inode);

	mext_inode_double_unlock(orig_inode, donor_inode);



	return ret;