From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:55268 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752372AbeCMOUb (ORCPT ); Tue, 13 Mar 2018 10:20:31 -0400 Subject: Patch "ext4: inplace xattr block update fails to deduplicate blocks" has been added to the 4.9-stable tree To: tahsin@google.com, adilger@dilger.ca, gregkh@linuxfoundation.org, tommi.t.rantala@nokia.com, tytso@mit.edu Cc: , From: Date: Tue, 13 Mar 2018 15:19:29 +0100 Message-ID: <1520950769127162@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled ext4: inplace xattr block update fails to deduplicate blocks to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: ext4-inplace-xattr-block-update-fails-to-deduplicate-blocks.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From ec00022030da5761518476096626338bd67df57a Mon Sep 17 00:00:00 2001 From: Tahsin Erdogan Date: Sat, 5 Aug 2017 22:41:42 -0400 Subject: ext4: inplace xattr block update fails to deduplicate blocks From: Tahsin Erdogan commit ec00022030da5761518476096626338bd67df57a upstream. When an xattr block has a single reference, block is updated inplace and it is reinserted to the cache. Later, a cache lookup is performed to see whether an existing block has the same contents. This cache lookup will most of the time return the just inserted entry so deduplication is not achieved. Running the following test script will produce two xattr blocks which can be observed in "File ACL: " line of debugfs output: mke2fs -b 1024 -I 128 -F -O extent /dev/sdb 1G mount /dev/sdb /mnt/sdb touch /mnt/sdb/{x,y} setfattr -n user.1 -v aaa /mnt/sdb/x setfattr -n user.2 -v bbb /mnt/sdb/x setfattr -n user.1 -v aaa /mnt/sdb/y setfattr -n user.2 -v bbb /mnt/sdb/y debugfs -R 'stat x' /dev/sdb | cat debugfs -R 'stat y' /dev/sdb | cat This patch defers the reinsertion to the cache so that we can locate other blocks with the same contents. Signed-off-by: Tahsin Erdogan Signed-off-by: Theodore Ts'o Reviewed-by: Andreas Dilger Signed-off-by: Tommi Rantala Signed-off-by: Greg Kroah-Hartman --- fs/ext4/xattr.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) --- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -837,8 +837,6 @@ ext4_xattr_block_set(handle_t *handle, s if (!IS_LAST_ENTRY(s->first)) ext4_xattr_rehash(header(s->base), s->here); - ext4_xattr_cache_insert(ext4_mb_cache, - bs->bh); } ext4_xattr_block_csum_set(inode, bs->bh); unlock_buffer(bs->bh); @@ -959,6 +957,7 @@ inserted: } else if (bs->bh && s->base == bs->bh->b_data) { /* We were modifying this block in-place. */ ea_bdebug(bs->bh, "keeping this block"); + ext4_xattr_cache_insert(ext4_mb_cache, bs->bh); new_bh = bs->bh; get_bh(new_bh); } else { Patches currently in stable-queue which might be from tahsin@google.com are queue-4.9/ext4-inplace-xattr-block-update-fails-to-deduplicate-blocks.patch