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Message-Id: <1346780214-29845-1-git-send-email-dmonakhov@openvz.org>
Date: Tue, 4 Sep 2012 21:36:51 +0400
From: Dmitry Monakhov <dmonakhov@...nvz.org>
To: linux-ext4@...r.kernel.org
Cc: jack@...e.cz, Dmitry Monakhov <dmonakhov@...nvz.org>
Subject: [PATCH 1/4] 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
- recheck ext4_should_dioread_nolock under extra i_dio_count reference.
Signed-off-by: Dmitry Monakhov <dmonakhov@...nvz.org>
---
fs/ext4/ext4.h | 2 ++
fs/ext4/ext4_jbd2.h | 2 ++
fs/ext4/indirect.c | 12 ++++++++++++
fs/ext4/inode.c | 5 +++++
fs/ext4/move_extent.c | 10 ++++++++++
5 files changed, 31 insertions(+), 0 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index f9024a6..36e8b84 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1349,6 +1349,8 @@ 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) \
diff --git a/fs/ext4/ext4_jbd2.h b/fs/ext4/ext4_jbd2.h
index 56d258c..318d177 100644
--- a/fs/ext4/ext4_jbd2.h
+++ b/fs/ext4/ext4_jbd2.h
@@ -399,6 +399,8 @@ static inline int ext4_should_dioread_nolock(struct inode *inode)
return 0;
if (ext4_should_journal_data(inode))
return 0;
+ if (ext4_test_inode_state(inode, EXT4_STATE_DIOREAD_LOCK))
+ return 0;
return 1;
}
diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c
index 830e1b2..ba40309 100644
--- a/fs/ext4/indirect.c
+++ b/fs/ext4/indirect.c
@@ -812,10 +812,22 @@ retry:
ext4_flush_completed_IO(inode);
mutex_unlock(&inode->i_mutex);
}
+ /*
+ * Inode's locking behaviour may change due to number
+ * of reasons, in order to be shure that nolock dioreads
+ * is still allowed we have to recheck inode's flags
+ * while i_dio_count > 0
+ */
+ atomic_inc(&inode->i_dio_count);
+ if (!unlikely(ext4_should_dioread_nolock(inode))) {
+ 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 d12d30e..58ef61a 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4741,6 +4741,10 @@ int ext4_change_inode_journal_flag(struct inode *inode, int val)
return err;
}
+ /* Wait for all existing dio workers */
+ ext4_set_inode_state(inode, EXT4_STATE_DIOREAD_LOCK);
+ inode_dio_wait(inode);
+
jbd2_journal_lock_updates(journal);
/*
@@ -4760,6 +4764,7 @@ int ext4_change_inode_journal_flag(struct inode *inode, int val)
ext4_set_aops(inode);
jbd2_journal_unlock_updates(journal);
+ ext4_clear_inode_state(inode, EXT4_STATE_DIOREAD_LOCK);
/* Finally we can mark the inode as dirty. */
diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
index c5826c6..a6a4278 100644
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -1213,6 +1213,14 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp,
ret1 = mext_inode_double_lock(orig_inode, donor_inode);
if (ret1 < 0)
return ret1;
+ /* Protect inodes against DIO workers
+ * - Disable dio nonlock reads, so all new dio workers will block
+ * on i_mutex.
+ * - wait for existing DIO in flight */
+ ext4_set_inode_state(orig_inode, EXT4_STATE_DIOREAD_LOCK);
+ ext4_set_inode_state(donor_inode, EXT4_STATE_DIOREAD_LOCK);
+ 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);
@@ -1412,6 +1420,8 @@ out:
kfree(holecheck_path);
}
double_up_write_data_sem(orig_inode, donor_inode);
+ ext4_clear_inode_state(orig_inode, EXT4_STATE_DIOREAD_LOCK);
+ ext4_clear_inode_state(donor_inode, EXT4_STATE_DIOREAD_LOCK);
ret2 = mext_inode_double_unlock(orig_inode, donor_inode);
if (ret1)
--
1.7.7.6
--
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