On Mon 27-09-10 18:54:52, Chris Mason wrote:
On Tue, Sep 28, 2010 at 12:25:48AM +0200, Jan Kara wrote:
[Added CCs for similar ecryptfs warning] On Thu 23-09-10 12:38:49, Andrew Morton wrote:
This started appearing for me on v2.6.36-rc5-49-gc79bd89; it did not happen on v2.6.36-rc5-33-g1ce1e41, probably because it does not have commit 692ebd17c2905313fff3c504c249c6a0faad16ec which introduces the warning. [...] device fsid 44d595920ddedfa-3ece6b56e80f689e devid 1 transid 22342 /dev/mapper/vg_cesarbinspiro-lv_home SELinux: initialized (dev dm-3, type btrfs), uses xattr ------------[ cut here ]------------ WARNING: at fs/fs-writeback.c:87 inode_to_bdi+0x62/0x6d() Hardware name: Inspiron N4010 Dirtiable inode bdi default != sb bdi btrfs Modules linked in: ipv6 kvm_intel kvm uinput arc4 ecb snd_hda_codec_intelhdmi snd_hda_codec_realtek iwlagn snd_hda_intel iwlcore snd_hda_codec uvcvideo snd_hwdep mac80211 videodev snd_seq snd_seq_device v4l1_compat snd_pcm atl1c v4l2_compat_ioctl32 btusb cfg80211 snd_timer i2c_i801 bluetooth iTCO_wdt dell_wmi dell_laptop snd pcspkr wmi dcdbas shpchp iTCO_vendor_support soundcore snd_page_alloc rfkill joydev microcode btrfs zlib_deflate libcrc32c cryptd aes_x86_64 aes_generic xts gf128mul dm_crypt usb_storage i915 drm_kms_helper drm i2c_algo_bit i2c_core video output [last unloaded: scsi_wait_scan] Pid: 1073, comm: find Not tainted 2.6.36-rc5+ #8 Call Trace: [<ffffffff8104d0e4>] warn_slowpath_common+0x85/0x9d [<ffffffff8104d19f>] warn_slowpath_fmt+0x46/0x48 [<ffffffff811308b7>] inode_to_bdi+0x62/0x6d [<ffffffff81131b48>] __mark_inode_dirty+0xd0/0x177 [<ffffffff81127168>] touch_atime+0x107/0x12a [<ffffffff81122384>] ? filldir+0x0/0xd0 [<ffffffff8112259b>] vfs_readdir+0x8d/0xb4 [<ffffffff8112270b>] sys_getdents+0x81/0xd1 [<ffffffff81009c72>] system_call_fastpath+0x16/0x1b
Thanks for the report. These bdi pointers are a mess. As Chris pointed out, btrfs forgets to properly initialize inode->i_mapping.backing_dev_info for directories and special inodes and thus these were previously attached to default_backing_dev_info which probably isn't what Chris would like to see.
There's no actual writeback for these, so it works fine for btrfs either way.
Ah, OK. I see you do all the writing already at inode dirtying time so you don't really care what happens after the dirtying for inodes without page cache. So it's really just a cosmetic issue for btrfs.
I've also got a similar report for ecryptfs which also does not initialize inode->i_mapping.backing_dev_info although it sets sb->s_bdi and thus again its inodes get filed to default_backing_dev_info lists. Quick search seems to reveal that other filesystems using handcrafted bdi's get it wrong as well and thus their inodes end up in the default_backing_dev_info lists which is generally undesirable (this was happening already before my patch, my code just started complaining about that). That suggests that we should probably handle such cases in a more generic way by changing the code in inode_init_always(). The patch below makes at least btrfs happy for me... Could you maybe test it? Thanks.
Christoph had a slightly different plan for this, I've cc'd him and kept the patch below for comment.
OK, thanks.
Honza
From 29f60c2b08ff9637a10439d1513805835ddcc746 Mon Sep 17 00:00:00 2001 From: Jan Kara jack@suse.cz Date: Mon, 27 Sep 2010 23:56:48 +0200 Subject: [PATCH] bdi: Initialize inode->i_mapping.backing_dev_info to sb->s_bdi
Currently, we initialize inode->i_mapping.backing_dev_info to the bdi of device sb->s_bdev points to. However there is quite a big number of filesystems that do not set sb->s_bdev (because they do not have one) but do set sb->s_bdi. These filesystems would generally benefit from setting inode->i_mapping.backing_dev_info to their s_bdi because otherwise their inodes would point to default_backing_dev_info and thus dirty inode tracking would happen there. So change inode initialization code to use sb->s_bdi if it is available.
Signed-off-by: Jan Kara jack@suse.cz
fs/inode.c | 22 ++++++++++++++-------- 1 files changed, 14 insertions(+), 8 deletions(-)
diff --git a/fs/inode.c b/fs/inode.c index 8646433..e415be4 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -172,15 +172,21 @@ int inode_init_always(struct super_block *sb, struct inode *inode) mapping->writeback_index = 0;
/*
* If the block_device provides a backing_dev_info for client
* inodes then use that. Otherwise the inode share the bdev's
* backing_dev_info.
* If the filesystem provides a backing_dev_info for client inodes
*/* then use that. Otherwise inodes share default_backing_dev_info.
- if (sb->s_bdev) {
struct backing_dev_info *bdi;
bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
mapping->backing_dev_info = bdi;
- if (sb->s_bdi && sb->s_bdi != &noop_backing_dev_info) {
/*
* Catch cases where filesystem might be bitten by using s_bdi
* instead of sb->s_bdev. Can be removed in 2.6.38.
*/
if (sb->s_bdev) {
struct backing_dev_info *bdi =
sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
WARN(bdi != sb->s_bdi, "s_bdev bdi %s != s_bdi %s\n",
bdi->name, sb->s_bdi->name);
}
} inode->i_private = NULL; inode->i_mapping = mapping;mapping->backing_dev_info = sb->s_bdi;
-- 1.6.4.2