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Message-Id: <1348847051-6746-7-git-send-email-dmonakhov@openvz.org>
Date: Fri, 28 Sep 2012 19:44:06 +0400
From: Dmitry Monakhov <dmonakhov@...nvz.org>
To: linux-ext4@...r.kernel.org
Cc: tytso@....edu, jack@...e.cz, lczerner@...hat.com,
Dmitry Monakhov <dmonakhov@...nvz.org>
Subject: [PATCH 06/11] ext4: serialize dio nonlocked reads with defrag workers V3
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 V2:
- fix mistype in condition
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@...nvz.org>
---
fs/ext4/ext4.h | 17 +++++++++++++++++
fs/ext4/indirect.c | 14 ++++++++++++++
fs/ext4/inode.c | 5 +++++
fs/ext4/move_extent.c | 8 ++++++++
4 files changed, 44 insertions(+), 0 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 9c3d004..885dc79 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1363,6 +1363,8 @@ 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) \
@@ -2471,6 +2473,21 @@ 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 ebc7d83..9e6cdb6 100644
--- a/fs/ext4/indirect.c
+++ b/fs/ext4/indirect.c
@@ -811,11 +811,25 @@ 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);
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 1ea34e5..da52855 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4692,6 +4692,10 @@ 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);
/*
@@ -4711,6 +4715,7 @@ 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 c2e47da..0aaaf12 100644
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -1325,6 +1325,12 @@ 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 */
@@ -1523,6 +1529,8 @@ 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;
--
1.7.7.6
--
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