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Commit 0893ed45 authored by Curt Wohlgemuth's avatar Curt Wohlgemuth Committed by Theodore Ts'o
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ext4: sync the directory inode in ext4_sync_parent() 



ext4 has taken the stance that, in the absence of a journal,
when an fsync/fdatasync of an inode is done, the parent
directory should be sync'ed if this inode entry is new.
ext4_sync_parent(), which implements this, does indeed sync
the dirent pages for parent directories, but it does not
sync the directory *inode*.  This patch fixes this.

Also now return error status from ext4_sync_parent().

I tested this using a power fail test, which panics a
machine running a file server getting requests from a
client.  Without this patch, on about every other test run,
the server is missing many, many files that had been synced.
With this patch, on > 6 runs, I see zero files being lost.

Google-Bug-Id: 4179519
Signed-off-by: default avatarCurt Wohlgemuth <curtw@google.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 04496411

fs/ext4/fsync.c

+14 −3
Original line number Diff line number Diff line
@@ -125,9 +125,11 @@ extern int ext4_flush_completed_IO(struct inode *inode) 
 * the parent directory's parent as well, and so on recursively, if

 * they are also freshly created.

 */

static void ext4_sync_parent(struct inode *inode)

static int ext4_sync_parent(struct inode *inode)

{

	struct writeback_control wbc;

	struct dentry *dentry = NULL;

	int ret = 0;



	while (inode && ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) {

		ext4_clear_inode_state(inode, EXT4_STATE_NEWENTRY);
@@ -136,8 +138,17 @@ static void ext4_sync_parent(struct inode *inode) 
		if (!dentry || !dentry->d_parent || !dentry->d_parent->d_inode)

			break;

		inode = dentry->d_parent->d_inode;

		sync_mapping_buffers(inode->i_mapping);

		ret = sync_mapping_buffers(inode->i_mapping);

		if (ret)

			break;

		memset(&wbc, 0, sizeof(wbc));

		wbc.sync_mode = WB_SYNC_ALL;

		wbc.nr_to_write = 0;         /* only write out the inode */

		ret = sync_inode(inode, &wbc);

		if (ret)

			break;

	}

	return ret;

}



/*
@@ -176,7 +187,7 @@ int ext4_sync_file(struct file *file, int datasync) 
	if (!journal) {

		ret = generic_file_fsync(file, datasync);

		if (!ret && !list_empty(&inode->i_dentry))

			ext4_sync_parent(inode);

			ret = ext4_sync_parent(inode);

		goto out;

	}