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.
Changes from V1:
- add missed memory bariers
- move DIOREAD_LOCK state check out from generic should_dioread_nolock
otherwise it will affect existing DIO readers.
Signed-off-by: Dmitry Monakhov <dmonakhov@xxxxxxxxxx>
---
fs/ext4/ext4.h | 17 +++++++++++++++++
fs/ext4/indirect.c | 13 +++++++++++++
fs/ext4/inode.c | 5 +++++
fs/ext4/move_extent.c | 8 ++++++++
4 files changed, 43 insertions(+), 0 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index be976ca..a71e299 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1348,6 +1348,8 @@ 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) \
@@ -2456,6 +2458,21 @@ 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 */
diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c
index 61f13e5..e4cc904 100644
--- a/fs/ext4/indirect.c
+++ b/fs/ext4/indirect.c
@@ -810,10 +810,23 @@ 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 retry;
+ }
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 {
ret = blockdev_direct_IO(rw, iocb, inode, iov,
offset, nr_segs, ext4_get_block);
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 762b955..c34d38c 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -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. */
diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
index c5826c6..ae0357b 100644
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -1214,6 +1214,12 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp,
if (ret1 < 0)
return ret1;
+ /* 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 */
@@ -1412,6 +1418,8 @@ out:
kfree(holecheck_path);
}
double_up_write_data_sem(orig_inode, donor_inode);
+ ext4_inode_block_unlocked_dio(orig_inode);
+ ext4_inode_block_unlocked_dio(donor_inode);
ret2 = mext_inode_double_unlock(orig_inode, donor_inode);
if (ret1)
--
1.7.7.6
--
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