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Date: Tue, 13 Jan 2009 15:30:12 +0100
From: Jan Kara <jack@...e.cz>
To: Theodore Tso <tytso@....edu>, Alan Cox <alan@...rguk.ukuu.org.uk>,
Pavel Machek <pavel@...e.cz>,
kernel list <linux-kernel@...r.kernel.org>, jack@...e.cz,
Jens Axboe <jens.axboe@...cle.com>
Subject: Re: ext2 + -osync: not as easy as it seems
On Tue 13-01-09 09:03:47, Theodore Tso wrote:
> Adding a barrier shouldn't be that hard; just a matter adding a call
> to blkdev_issue_flush() to ext2_sync_file() before it returns.
Yes. Something like the patch below?
But it's not the whole story. Strictly speaking we should also call
blkdev_issue_flush() whenever we write things because of O_SYNC or
O_DIRSYNC flags. My patch does also that (it's based on the previous ext2
patch I've sent a while before).
Honza
--
Jan Kara <jack@...e.cz>
SUSE Labs, CR
---
>From 0f5a1865a9f1538886699c5d13d3527343c88c11 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@...e.cz>
Date: Tue, 13 Jan 2009 15:09:18 +0100
Subject: [PATCH] ext2: Add blk_issue_flush() to syncing paths
To be really safe that the data hit the platter, we should also flush drive's
writeback caches on fsync and for O_SYNC files or O_DIRSYNC inodes.
Signed-off-by: Jan Kara <jack@...e.cz>
---
fs/ext2/dir.c | 5 ++++-
fs/ext2/fsync.c | 7 +++++--
fs/ext2/inode.c | 7 +++++++
fs/ext2/xattr.c | 6 +++++-
4 files changed, 21 insertions(+), 4 deletions(-)
diff --git a/fs/ext2/dir.c b/fs/ext2/dir.c
index 7fba549..9ab9347 100644
--- a/fs/ext2/dir.c
+++ b/fs/ext2/dir.c
@@ -25,6 +25,7 @@
#include <linux/buffer_head.h>
#include <linux/pagemap.h>
#include <linux/swap.h>
+#include <linux/blkdev.h> /* for blkdev_issue_flush() */
typedef struct ext2_dir_entry_2 ext2_dirent;
@@ -96,8 +97,10 @@ static int ext2_commit_chunk(struct page *page, loff_t pos, unsigned len)
}
unlock_page(page);
- if (IS_DIRSYNC(dir))
+ if (IS_DIRSYNC(dir)) {
err = ext2_sync_inode(dir);
+ blkdev_issue_flush(dir->i_sb->s_bdev, NULL);
+ }
return err;
}
diff --git a/fs/ext2/fsync.c b/fs/ext2/fsync.c
index fc66c93..9cd1838 100644
--- a/fs/ext2/fsync.c
+++ b/fs/ext2/fsync.c
@@ -24,6 +24,7 @@
#include "ext2.h"
#include <linux/buffer_head.h> /* for sync_mapping_buffers() */
+#include <linux/blkdev.h> /* for blkdev_issue_flush() */
/*
@@ -39,12 +40,14 @@ int ext2_sync_file(struct file *file, struct dentry *dentry, int datasync)
ret = sync_mapping_buffers(inode->i_mapping);
if (!(inode->i_state & I_DIRTY))
- return ret;
+ goto out;
if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
- return ret;
+ goto out;
err = ext2_sync_inode(inode);
if (ret == 0)
ret = err;
+out:
+ blkdev_issue_flush(inode->i_sb->s_bdev, NULL);
return ret;
}
diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index 23fff2f..49b479e 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -33,6 +33,7 @@
#include <linux/mpage.h>
#include <linux/fiemap.h>
#include <linux/namei.h>
+#include <linux/blkdev.h> /* for blkdev_issue_flush() */
#include "ext2.h"
#include "acl.h"
#include "xip.h"
@@ -68,9 +69,14 @@ void ext2_delete_inode (struct inode * inode)
mark_inode_dirty(inode);
ext2_update_inode(inode, inode_needs_sync(inode));
+ /* Make sure inode deletion really gets to disk. Disk write caches
+ * are flushed either in ext2_truncate() or we do it explicitly */
inode->i_size = 0;
if (inode->i_blocks)
ext2_truncate (inode);
+ else if (inode_needs_sync(inode))
+ blkdev_issue_flush(inode->i_sb->s_bdev, NULL);
+
ext2_free_inode (inode);
return;
@@ -1104,6 +1110,7 @@ do_indirects:
if (inode_needs_sync(inode)) {
sync_mapping_buffers(inode->i_mapping);
ext2_sync_inode (inode);
+ blkdev_issue_flush(inode->i_sb->s_bdev, NULL);
} else {
mark_inode_dirty(inode);
}
diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c
index 987a526..d480216 100644
--- a/fs/ext2/xattr.c
+++ b/fs/ext2/xattr.c
@@ -60,6 +60,7 @@
#include <linux/mbcache.h>
#include <linux/quotaops.h>
#include <linux/rwsem.h>
+#include <linux/blkdev.h> /* for blkdev_issue_flush() */
#include "ext2.h"
#include "xattr.h"
#include "acl.h"
@@ -702,6 +703,7 @@ ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh,
DQUOT_FREE_BLOCK(inode, 1);
goto cleanup;
}
+ blkdev_issue_flush(sb->s_bdev, NULL);
} else
mark_inode_dirty(inode);
@@ -792,8 +794,10 @@ ext2_xattr_delete_inode(struct inode *inode)
le32_to_cpu(HDR(bh)->h_refcount));
unlock_buffer(bh);
mark_buffer_dirty(bh);
- if (IS_SYNC(inode))
+ if (IS_SYNC(inode)) {
sync_dirty_buffer(bh);
+ blkdev_issue_flush(inode->i_sb->s_bdev, NULL);
+ }
DQUOT_FREE_BLOCK(inode, 1);
}
EXT2_I(inode)->i_file_acl = 0;
--
1.6.0.2
--
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