[3.13.y-ckt stable] Patch "ext4: make fsync to sync parent dir in no-journal for real this time" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    ext4: make fsync to sync parent dir in no-journal for real this time

to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11-ckt21.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From dfea45bb1ce393af5349952f33c4a8e6f3812e10 Mon Sep 17 00:00:00 2001
From: Lukas Czerner <lczerner at redhat.com>
Date: Fri, 3 Apr 2015 10:46:58 -0400
Subject: ext4: make fsync to sync parent dir in no-journal for real this time

commit e12fb97222fc41e8442896934f76d39ef99b590a upstream.

Previously commit 14ece1028b3ed53ffec1b1213ffc6acaf79ad77c added a
support for for syncing parent directory of newly created inodes to
make sure that the inode is not lost after a power failure in
no-journal mode.

However this does not work in majority of cases, namely:
 - if the directory has inline data
 - if the directory is already indexed
 - if the directory already has at least one block and:
	- the new entry fits into it
	- or we've successfully converted it to indexed

So in those cases we might lose the inode entirely even after fsync in
the no-journal mode. This also includes ext2 default mode obviously.

I've noticed this while running xfstest generic/321 and even though the
test should fail (we need to run fsck after a crash in no-journal mode)
I could not find a newly created entries even when if it was fsynced
before.

Fix this by adjusting the ext4_add_entry() successful exit paths to set
the inode EXT4_STATE_NEWENTRY so that fsync has the chance to fsync the
parent directory as well.

Signed-off-by: Lukas Czerner <lczerner at redhat.com>
Signed-off-by: Theodore Ts'o <tytso at mit.edu>
Reviewed-by: Jan Kara <jack at suse.cz>
Cc: Frank Mayhar <fmayhar at google.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 fs/ext4/namei.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index c8fd7ce..18b895f 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -1878,7 +1878,7 @@ static int ext4_add_entry(handle_t *handle, struct dentry *dentry,
 			  struct inode *inode)
 {
 	struct inode *dir = dentry->d_parent->d_inode;
-	struct buffer_head *bh;
+	struct buffer_head *bh = NULL;
 	struct ext4_dir_entry_2 *de;
 	struct ext4_dir_entry_tail *t;
 	struct super_block *sb;
@@ -1902,14 +1902,14 @@ static int ext4_add_entry(handle_t *handle, struct dentry *dentry,
 			return retval;
 		if (retval == 1) {
 			retval = 0;
-			return retval;
+			goto out;
 		}
 	}

 	if (is_dx(dir)) {
 		retval = ext4_dx_add_entry(handle, dentry, inode);
 		if (!retval || (retval != ERR_BAD_DX_DIR))
-			return retval;
+			goto out;
 		ext4_clear_inode_flag(dir, EXT4_INODE_INDEX);
 		dx_fallback++;
 		ext4_mark_inode_dirty(handle, dir);
@@ -1921,14 +1921,15 @@ static int ext4_add_entry(handle_t *handle, struct dentry *dentry,
 			return PTR_ERR(bh);

 		retval = add_dirent_to_buf(handle, dentry, inode, NULL, bh);
-		if (retval != -ENOSPC) {
-			brelse(bh);
-			return retval;
-		}
+		if (retval != -ENOSPC)
+			goto out;

 		if (blocks == 1 && !dx_fallback &&
-		    EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_DIR_INDEX))
-			return make_indexed_dir(handle, dentry, inode, bh);
+		    EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_DIR_INDEX)) {
+			retval = make_indexed_dir(handle, dentry, inode, bh);
+			bh = NULL; /* make_indexed_dir releases bh */
+			goto out;
+		}
 		brelse(bh);
 	}
 	bh = ext4_append(handle, dir, &block);
@@ -1944,6 +1945,7 @@ static int ext4_add_entry(handle_t *handle, struct dentry *dentry,
 	}

 	retval = add_dirent_to_buf(handle, dentry, inode, de, bh);
+out:
 	brelse(bh);
 	if (retval == 0)
 		ext4_set_inode_state(inode, EXT4_STATE_NEWENTRY);
--
1.9.1