Messages in this thread Patch in this message | | | Subject | Re: backporting "ext4: inplace xattr block update fails to deduplicate blocks" to LTS kernels? | From | Tommi Rantala <> | Date | Thu, 22 Feb 2018 15:37:54 +0200 |
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On 21.02.2018 17:56, Theodore Ts'o wrote: > On Wed, Feb 21, 2018 at 12:40:00PM +0100, Greg Kroah-Hartman wrote: >> On Mon, Feb 19, 2018 at 03:26:37PM +0200, Tommi Rantala wrote: >>> >>> OK to backport it? >>> I tested it briefly in 4.9, seems to work. > > It looks sane, but it would be nice if I can get people who are > backporting ext4 patches to make sure there are no regressions using > one of kvm-xfstests[1] or gce-xfstests[2][3]..... > > [1] https://github.com/tytso/xfstests-bld/blob/master/Documentation/kvm-xfstests.md > [2] https://github.com/tytso/xfstests-bld/blob/master/Documentation/gce-xfstests.md > [3] https://thunk.org/gce-xfstests > > I do run regression tests[4] on stable kernels when I have time, but > it scales much better when other people can help. > > [4] https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git/tag/?h=ext4-4.9.54-1 > >> I need an ack from the ext4 maintainers before I can take this... > > Greg, you can go ahead and take this, but in the future I'd appreciate > it if ext4 backporters could at least run a smoke test (which takes > less than 15 minutes on GCE) before and after the patch, and report no > test regressions.
Thanks for the instructions!
Smoke test results 4.9.82 with and without the patch (attached, to avoid email client mangling it), no new failures:
-------------------- Summary report KERNEL: kernel 4.9.82-xfstests #2 SMP Thu Feb 22 14:58:27 EET 2018 x86_64 CPUS: 2 MEM: 1989.2
ext4/4k: 271 tests, 7 failures, 34 skipped, 737 seconds Failures: generic/081 generic/383 generic/384 generic/386 generic/441 generic/451 generic/472 Totals: 271 tests, 34 skipped, 7 failures, 0 errors, 685s
-------------------- Summary report KERNEL: kernel 4.9.82-xfstests-00001-gb98ae0251413 #1 SMP Thu Feb 22 14:31:01 EET 2018 x86_64 CPUS: 2 MEM: 1989.2
ext4/4k: 271 tests, 7 failures, 34 skipped, 749 seconds Failures: generic/081 generic/383 generic/384 generic/386 generic/441 generic/451 generic/472 Totals: 271 tests, 34 skipped, 7 failures, 0 errors, 694s
FSTESTVER: e2fsprogs v1.43.6-85-g7595699d0 (Wed, 6 Sep 2017 22:04:14 -0400) FSTESTVER: fio fio-3.2 (Fri, 3 Nov 2017 15:23:49 -0600) FSTESTVER: quota 4d81e8b (Mon, 16 Oct 2017 09:42:44 +0200) FSTESTVER: stress-ng 977ae35 (Wed, 6 Sep 2017 23:45:03 -0400) FSTESTVER: xfsprogs v4.14.0-rc2-1-g19ca9b0b (Mon, 27 Nov 2017 10:56:21 -0600) FSTESTVER: xfstests-bld ff7b8c2 (Wed, 13 Dec 2017 21:24:24 -0500) FSTESTVER: xfstests linux-v3.8-1832-gafeee2d9 (Sun, 31 Dec 2017 13:35:28 -0500) FSTESTCFG: 4k FSTESTSET: -g quick FSTESTOPT: aex
Tommi From b98ae025141361b9e92fdd470dfd2314a64a47d0 Mon Sep 17 00:00:00 2001 From: Tahsin Erdogan <tahsin@google.com> Date: Sat, 5 Aug 2017 22:41:42 -0400 Subject: [PATCH] ext4: inplace xattr block update fails to deduplicate blocks
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 <tahsin@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Andreas Dilger <adilger@dilger.ca> Signed-off-by: Tommi Rantala <tommi.t.rantala@nokia.com> --- fs/ext4/xattr.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c index 3eeed8f0aa06..3fadfabcac39 100644 --- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -837,8 +837,6 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode, 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 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode, } 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 { -- 2.14.3
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