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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: Jan Kara <jack@suse.cz>
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Dmitry Monakhov 2012-09-29 00:41:21 -04:00 committed by Theodore Ts'o
parent 28a535f9a0
commit 17335dcc47
4 changed files with 44 additions and 0 deletions
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17
fs/ext4/ext4.h
View File

@ -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 */

14
fs/ext4/indirect.c
View File

@ -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);

5
fs/ext4/inode.c
View File

@ -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. */

8
fs/ext4/move_extent.c
View File

@ -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;