btrfs hang on brd

Hi

I seem to be able to get btrfs reproducibly to
produce warnings and finally hang when running
a stress test on a ramdisk.

Testing was done using the "integration-test" branch of btrfs-unstable. Note that I also tested v2.6.39 and "integration-test" took much longer to hang i.e. it is an improvement

The test script and stack dumps are below.

Is this a valid test?

Is it worth me investigating these?

Regards
Adrian

Test
----

#!/bin/sh

sudo modprobe brd rd_size=262144

sudo umount /mnt/test/ 2> /dev/null

echo 'mkfs.btrfs /dev/ram0'

sudo mkfs.btrfs /dev/ram0

sudo mkdir -p /mnt/test

echo 'mount -t btrfs /dev/ram0 /mnt/test'

sudo mount -t btrfs /dev/ram0 /mnt/test

sudo mkdir -p /mnt/test/test

sudo chown $USER /mnt/test/test
sudo chgrp $USER /mnt/test/test

sudo umount /mnt/test

full=0
i=0
while true; do

	sudo mount -t btrfs /dev/ram0 /mnt/test

	if df | grep ram0 | grep 100% > /dev/null; then
		full=`expr $full \+ 1`
		if test $full -gt 6;then
			rm -rf /mnt/test/test/*
			full=0
		fi
	else
		full=0
	fi

	fsstress -c -r -d /mnt/test/test -p 3 -n 1000 -l 10

	sudo umount /mnt/test

	i=`expr $i \+ 1`
	echo $i

done

Stack dumps for warnings
------------------------

[ 7481.520750] WARNING: at fs/btrfs/extent-tree.c:5648 btrfs_alloc_free_block+0x14e/0x357 [btrfs]()
[ 7481.520753] Hardware name: XPS 8300
[ 7481.520754] Modules linked in: tcp_lp tun btrfs zlib_deflate libcrc32c brd fuse cpufreq_ondemand acpi_cpufreq freq_table mperf ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables ipv6 uinput snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec broadcom tg3 snd_hwdep snd_seq snd_seq_device snd_pcm joydev pcspkr iTCO_wdt iTCO_vendor_support dcdbas serio_raw i2c_i801 snd_timer snd microcode soundcore snd_page_alloc usb_storage i915 drm_kms_helper drm i2c_algo_bit i2c_core video [last unloaded: scsi_wait_scan]
[ 7481.520805] Pid: 3980, comm: btrfs-endio-wri Not tainted 2.6.39-integration-test-20110526-01+ #2
[ 7481.520808] Call Trace:
[ 7481.520818]  [<ffffffff8104df7a>] warn_slowpath_common+0x85/0x9d
[ 7481.520824]  [<ffffffff8104dfac>] warn_slowpath_null+0x1a/0x1c
[ 7481.520838]  [<ffffffffa02dfca8>] btrfs_alloc_free_block+0x14e/0x357 [btrfs]
[ 7481.520865]  [<ffffffffa030a073>] ? map_private_extent_buffer+0xb1/0xd5 [btrfs]
[ 7481.520875]  [<ffffffffa02d2987>] __btrfs_cow_block+0x102/0x31e [btrfs]
[ 7481.520883]  [<ffffffffa02d1300>] ? btrfs_set_item_key+0x3/0x20 [btrfs]
[ 7481.520892]  [<ffffffffa02d2ca7>] btrfs_cow_block+0x104/0x14d [btrfs]
[ 7481.520910]  [<ffffffffa02d5a87>] btrfs_search_slot+0x162/0x502 [btrfs]
[ 7481.520925]  [<ffffffffa02e3e66>] btrfs_lookup_file_extent+0x3c/0x3e [btrfs]
[ 7481.520936]  [<ffffffffa02d2124>] ? btrfs_alloc_path+0x1a/0x2b [btrfs]
[ 7481.520955]  [<ffffffffa02f9319>] btrfs_drop_extents+0x10e/0x731 [btrfs]
[ 7481.520960]  [<ffffffff8103cc9e>] ? need_resched+0x23/0x2d
[ 7481.520966]  [<ffffffff81474da6>] ? _cond_resched+0xe/0x22
[ 7481.520972]  [<ffffffff8110d58c>] ? slab_pre_alloc_hook.clone.32+0x2d/0x31
[ 7481.520977]  [<ffffffff8110e0c7>] ? kmem_cache_alloc+0x29/0xf7
[ 7481.521002]  [<ffffffffa02f09fa>] insert_reserved_file_extent.clone.34+0x70/0x1fc [btrfs]
[ 7481.521027]  [<ffffffffa03071c9>] ? lock_extent_bits+0x5e/0xa8 [btrfs]
[ 7481.521044]  [<ffffffffa02f362c>] btrfs_endio_direct_write+0x171/0x29a [btrfs]
[ 7481.521060]  [<ffffffffa02e6afc>] ? end_workqueue_fn+0xf6/0x10e [btrfs]
[ 7481.521065]  [<ffffffff81141934>] bio_endio+0x2d/0x2f
[ 7481.521087]  [<ffffffffa02e6b07>] end_workqueue_fn+0x101/0x10e [btrfs]
[ 7481.521101]  [<ffffffffa0310951>] worker_loop+0x193/0x4ca [btrfs]
[ 7481.521116]  [<ffffffffa03107be>] ? btrfs_queue_worker+0x214/0x214 [btrfs]
[ 7481.521119]  [<ffffffff81068dce>] kthread+0x82/0x8a
[ 7481.521124]  [<ffffffff8147db64>] kernel_thread_helper+0x4/0x10
[ 7481.521136]  [<ffffffff81068d4c>] ? kthread_worker_fn+0x14b/0x14b
[ 7481.521141]  [<ffffffff8147db60>] ? gs_change+0x13/0x13
[ 7481.521144] ---[ end trace abb147a5624a0a24 ]---
[ 7481.521161] ------------[ cut here ]------------
[ 7481.521176] WARNING: at fs/btrfs/extent-tree.c:5648 btrfs_alloc_free_block+0x14e/0x357 [btrfs]()
[ 7481.521178] Hardware name: XPS 8300
[ 7481.521180] Modules linked in: tcp_lp tun btrfs zlib_deflate libcrc32c brd fuse cpufreq_ondemand acpi_cpufreq freq_table mperf ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables ipv6 uinput snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec broadcom tg3 snd_hwdep snd_seq snd_seq_device snd_pcm joydev pcspkr iTCO_wdt iTCO_vendor_support dcdbas serio_raw i2c_i801 snd_timer snd microcode soundcore snd_page_alloc usb_storage i915 drm_kms_helper drm i2c_algo_bit i2c_core video [last unloaded: scsi_wait_scan]
[ 7481.521237] Pid: 3980, comm: btrfs-endio-wri Tainted: G        W 2.6.39-integration-test-20110526-01+ #2
[ 7481.521240] Call Trace:
[ 7481.521245]  [<ffffffff8104df7a>] warn_slowpath_common+0x85/0x9d
[ 7481.521250]  [<ffffffff8104dfac>] warn_slowpath_null+0x1a/0x1c
[ 7481.521288]  [<ffffffffa02dfca8>] btrfs_alloc_free_block+0x14e/0x357 [btrfs]
[ 7481.521303]  [<ffffffffa030a073>] ? map_private_extent_buffer+0xb1/0xd5 [btrfs]
[ 7481.521313]  [<ffffffffa02d2987>] __btrfs_cow_block+0x102/0x31e [btrfs]
[ 7481.521322]  [<ffffffffa02d1300>] ? btrfs_set_item_key+0x3/0x20 [btrfs]
[ 7481.521341]  [<ffffffffa02d2ca7>] btrfs_cow_block+0x104/0x14d [btrfs]
[ 7481.521353]  [<ffffffffa02d5a87>] btrfs_search_slot+0x162/0x502 [btrfs]
[ 7481.521378]  [<ffffffffa02e3e66>] btrfs_lookup_file_extent+0x3c/0x3e [btrfs]
[ 7481.521388]  [<ffffffffa02d2124>] ? btrfs_alloc_path+0x1a/0x2b [btrfs]
[ 7481.521405]  [<ffffffffa02f9319>] btrfs_drop_extents+0x10e/0x731 [btrfs]
[ 7481.521410]  [<ffffffff8103cc9e>] ? need_resched+0x23/0x2d
[ 7481.521415]  [<ffffffff81474da6>] ? _cond_resched+0xe/0x22
[ 7481.521420]  [<ffffffff8110d58c>] ? slab_pre_alloc_hook.clone.32+0x2d/0x31
[ 7481.521426]  [<ffffffff8110e0c7>] ? kmem_cache_alloc+0x29/0xf7
[ 7481.521441]  [<ffffffffa02f09fa>] insert_reserved_file_extent.clone.34+0x70/0x1fc [btrfs]
[ 7481.521470]  [<ffffffffa03071c9>] ? lock_extent_bits+0x5e/0xa8 [btrfs]
[ 7481.521496]  [<ffffffffa02f362c>] btrfs_endio_direct_write+0x171/0x29a [btrfs]
[ 7481.521511]  [<ffffffffa02e6afc>] ? end_workqueue_fn+0xf6/0x10e [btrfs]
[ 7481.521516]  [<ffffffff81141934>] bio_endio+0x2d/0x2f
[ 7481.521539]  [<ffffffffa02e6b07>] end_workqueue_fn+0x101/0x10e [btrfs]
[ 7481.521565]  [<ffffffffa0310951>] worker_loop+0x193/0x4ca [btrfs]
[ 7481.521581]  [<ffffffffa03107be>] ? btrfs_queue_worker+0x214/0x214 [btrfs]
[ 7481.521586]  [<ffffffff81068dce>] kthread+0x82/0x8a
[ 7481.521591]  [<ffffffff8147db64>] kernel_thread_helper+0x4/0x10
[ 7481.521596]  [<ffffffff81068d4c>] ? kthread_worker_fn+0x14b/0x14b
[ 7481.521601]  [<ffffffff8147db60>] ? gs_change+0x13/0x13
[ 7481.521604] ---[ end trace abb147a5624a0a25 ]---
[ 7481.521639] ------------[ cut here ]------------
[ 7481.521654] WARNING: at fs/btrfs/extent-tree.c:5648 btrfs_alloc_free_block+0x14e/0x357 [btrfs]()
[ 7481.521658] Hardware name: XPS 8300
[ 7481.521669] Modules linked in: tcp_lp tun btrfs zlib_deflate libcrc32c brd fuse cpufreq_ondemand acpi_cpufreq freq_table mperf ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables ipv6 uinput snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec broadcom tg3 snd_hwdep snd_seq snd_seq_device snd_pcm joydev pcspkr iTCO_wdt iTCO_vendor_support dcdbas serio_raw i2c_i801 snd_timer snd microcode soundcore snd_page_alloc usb_storage i915 drm_kms_helper drm i2c_algo_bit i2c_core video [last unloaded: scsi_wait_scan]
[ 7481.521736] Pid: 3980, comm: btrfs-endio-wri Tainted: G        W 2.6.39-integration-test-20110526-01+ #2
[ 7481.521739] Call Trace:
[ 7481.521745]  [<ffffffff8104df7a>] warn_slowpath_common+0x85/0x9d
[ 7481.521750]  [<ffffffff8104dfac>] warn_slowpath_null+0x1a/0x1c
[ 7481.521763]  [<ffffffffa02dfca8>] btrfs_alloc_free_block+0x14e/0x357 [btrfs]
[ 7481.521773]  [<ffffffffa02d127f>] ? btrfs_item_offset_nr+0x19/0x1b [btrfs]
[ 7481.521783]  [<ffffffffa02d1551>] ? leaf_space_used+0x5e/0x86 [btrfs]
[ 7481.521803]  [<ffffffffa02d2987>] __btrfs_cow_block+0x102/0x31e [btrfs]
[ 7481.521822]  [<ffffffffa0309674>] ? clear_extent_buffer_dirty+0x131/0x142 [btrfs]
[ 7481.521834]  [<ffffffffa02d1500>] ? leaf_space_used+0xd/0x86 [btrfs]
[ 7481.521845]  [<ffffffffa02d2ca7>] btrfs_cow_block+0x104/0x14d [btrfs]
[ 7481.521864]  [<ffffffffa0314f32>] ? btrfs_spin_on_block+0x55/0x55 [btrfs]
[ 7481.521876]  [<ffffffffa02d5a87>] btrfs_search_slot+0x162/0x502 [btrfs]
[ 7481.521889]  [<ffffffffa02d6d2d>] btrfs_insert_empty_items+0x6a/0xba [btrfs]
[ 7481.521895]  [<ffffffff8110e0c7>] ? kmem_cache_alloc+0x29/0xf7
[ 7481.521921]  [<ffffffffa02f0a37>] insert_reserved_file_extent.clone.34+0xad/0x1fc [btrfs]
[ 7481.521947]  [<ffffffffa03071c9>] ? lock_extent_bits+0x5e/0xa8 [btrfs]
[ 7481.521965]  [<ffffffffa02f362c>] btrfs_endio_direct_write+0x171/0x29a [btrfs]
[ 7481.521989]  [<ffffffffa02e6afc>] ? end_workqueue_fn+0xf6/0x10e [btrfs]
[ 7481.521994]  [<ffffffff81141934>] bio_endio+0x2d/0x2f
[ 7481.522007]  [<ffffffffa02e6b07>] end_workqueue_fn+0x101/0x10e [btrfs]
[ 7481.522034]  [<ffffffffa0310951>] worker_loop+0x193/0x4ca [btrfs]
[ 7481.522052]  [<ffffffffa03107be>] ? btrfs_queue_worker+0x214/0x214 [btrfs]
[ 7481.522057]  [<ffffffff81068dce>] kthread+0x82/0x8a
[ 7481.522071]  [<ffffffff8147db64>] kernel_thread_helper+0x4/0x10
[ 7481.522076]  [<ffffffff81068d4c>] ? kthread_worker_fn+0x14b/0x14b
[ 7481.522081]  [<ffffffff8147db60>] ? gs_change+0x13/0x13
[ 7481.522084] ---[ end trace abb147a5624a0a26 ]---
[ 7481.522108] ------------[ cut here ]------------
[ 7481.522123] WARNING: at fs/btrfs/extent-tree.c:5648 btrfs_alloc_free_block+0x14e/0x357 [btrfs]()
[ 7481.522126] Hardware name: XPS 8300
[ 7481.522128] Modules linked in: tcp_lp tun btrfs zlib_deflate libcrc32c brd fuse cpufreq_ondemand acpi_cpufreq freq_table mperf ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables ipv6 uinput snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec broadcom tg3 snd_hwdep snd_seq snd_seq_device snd_pcm joydev pcspkr iTCO_wdt iTCO_vendor_support dcdbas serio_raw i2c_i801 snd_timer snd microcode soundcore snd_page_alloc usb_storage i915 drm_kms_helper drm i2c_algo_bit i2c_core video [last unloaded: scsi_wait_scan]
[ 7481.522203] Pid: 3980, comm: btrfs-endio-wri Tainted: G        W 2.6.39-integration-test-20110526-01+ #2
[ 7481.522206] Call Trace:
[ 7481.522211]  [<ffffffff8104df7a>] warn_slowpath_common+0x85/0x9d
[ 7481.522226]  [<ffffffff8104dfac>] warn_slowpath_null+0x1a/0x1c
[ 7481.522240]  [<ffffffffa02dfca8>] btrfs_alloc_free_block+0x14e/0x357 [btrfs]
[ 7481.522269]  [<ffffffffa030a073>] ? map_private_extent_buffer+0xb1/0xd5 [btrfs]
[ 7481.522283]  [<ffffffffa02d2987>] __btrfs_cow_block+0x102/0x31e [btrfs]
[ 7481.522293]  [<ffffffffa02d1500>] ? leaf_space_used+0xd/0x86 [btrfs]
[ 7481.522304]  [<ffffffffa02d2ca7>] btrfs_cow_block+0x104/0x14d [btrfs]
[ 7481.522315]  [<ffffffffa02d5a87>] btrfs_search_slot+0x162/0x502 [btrfs]
[ 7481.522326]  [<ffffffffa02d6d2d>] btrfs_insert_empty_items+0x6a/0xba [btrfs]
[ 7481.522332]  [<ffffffff8110e0c7>] ? kmem_cache_alloc+0x29/0xf7
[ 7481.522359]  [<ffffffffa02f0a37>] insert_reserved_file_extent.clone.34+0xad/0x1fc [btrfs]
[ 7481.522385]  [<ffffffffa03071c9>] ? lock_extent_bits+0x5e/0xa8 [btrfs]
[ 7481.522401]  [<ffffffffa02f362c>] btrfs_endio_direct_write+0x171/0x29a [btrfs]
[ 7481.522415]  [<ffffffffa02e6afc>] ? end_workqueue_fn+0xf6/0x10e [btrfs]
[ 7481.522420]  [<ffffffff81141934>] bio_endio+0x2d/0x2f
[ 7481.522433]  [<ffffffffa02e6b07>] end_workqueue_fn+0x101/0x10e [btrfs]
[ 7481.522459]  [<ffffffffa0310951>] worker_loop+0x193/0x4ca [btrfs]
[ 7481.522477]  [<ffffffffa03107be>] ? btrfs_queue_worker+0x214/0x214 [btrfs]
[ 7481.522482]  [<ffffffff81068dce>] kthread+0x82/0x8a
[ 7481.522488]  [<ffffffff8147db64>] kernel_thread_helper+0x4/0x10
[ 7481.522493]  [<ffffffff81068d4c>] ? kthread_worker_fn+0x14b/0x14b
[ 7481.522499]  [<ffffffff8147db60>] ? gs_change+0x13/0x13
[ 7481.522502] ---[ end trace abb147a5624a0a27 ]---
[ 7481.522526] ------------[ cut here ]------------
[ 7481.522549] WARNING: at fs/btrfs/extent-tree.c:5648 btrfs_alloc_free_block+0x14e/0x357 [btrfs]()
[ 7481.522552] Hardware name: XPS 8300
[ 7481.522555] Modules linked in: tcp_lp tun btrfs zlib_deflate libcrc32c brd fuse cpufreq_ondemand acpi_cpufreq freq_table mperf ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables ipv6 uinput snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec broadcom tg3 snd_hwdep snd_seq snd_seq_device snd_pcm joydev pcspkr iTCO_wdt iTCO_vendor_support dcdbas serio_raw i2c_i801 snd_timer snd microcode soundcore snd_page_alloc usb_storage i915 drm_kms_helper drm i2c_algo_bit i2c_core video [last unloaded: scsi_wait_scan]
[ 7481.522651] Pid: 3980, comm: btrfs-endio-wri Tainted: G        W 2.6.39-integration-test-20110526-01+ #2
[ 7481.522654] Call Trace:
[ 7481.522659]  [<ffffffff8104df7a>] warn_slowpath_common+0x85/0x9d
[ 7481.522665]  [<ffffffff8104dfac>] warn_slowpath_null+0x1a/0x1c
[ 7481.522686]  [<ffffffffa02dfca8>] btrfs_alloc_free_block+0x14e/0x357 [btrfs]
[ 7481.522705]  [<ffffffffa030a073>] ? map_private_extent_buffer+0xb1/0xd5 [btrfs]
[ 7481.522726]  [<ffffffffa02d2987>] __btrfs_cow_block+0x102/0x31e [btrfs]
[ 7481.522736]  [<ffffffffa02d1500>] ? leaf_space_used+0xd/0x86 [btrfs]
[ 7481.522746]  [<ffffffffa02d2ca7>] btrfs_cow_block+0x104/0x14d [btrfs]
[ 7481.522767]  [<ffffffffa02d5a87>] btrfs_search_slot+0x162/0x502 [btrfs]
[ 7481.522780]  [<ffffffffa02d6d2d>] btrfs_insert_empty_items+0x6a/0xba [btrfs]
[ 7481.522786]  [<ffffffff8110e0c7>] ? kmem_cache_alloc+0x29/0xf7
[ 7481.522812]  [<ffffffffa02f0a37>] insert_reserved_file_extent.clone.34+0xad/0x1fc [btrfs]
[ 7481.522838]  [<ffffffffa03071c9>] ? lock_extent_bits+0x5e/0xa8 [btrfs]
[ 7481.522856]  [<ffffffffa02f362c>] btrfs_endio_direct_write+0x171/0x29a [btrfs]
[ 7481.522872]  [<ffffffffa02e6afc>] ? end_workqueue_fn+0xf6/0x10e [btrfs]
[ 7481.522886]  [<ffffffff81141934>] bio_endio+0x2d/0x2f
[ 7481.522899]  [<ffffffffa02e6b07>] end_workqueue_fn+0x101/0x10e [btrfs]
[ 7481.522925]  [<ffffffffa0310951>] worker_loop+0x193/0x4ca [btrfs]
[ 7481.522942]  [<ffffffffa03107be>] ? btrfs_queue_worker+0x214/0x214 [btrfs]
[ 7481.522948]  [<ffffffff81068dce>] kthread+0x82/0x8a
[ 7481.522962]  [<ffffffff8147db64>] kernel_thread_helper+0x4/0x10
[ 7481.522967]  [<ffffffff81068d4c>] ? kthread_worker_fn+0x14b/0x14b
[ 7481.522972]  [<ffffffff8147db60>] ? gs_change+0x13/0x13
[ 7481.522975] ---[ end trace abb147a5624a0a28 ]---

Stack dumps for more warnings
------------------------------

[21976.930845] WARNING: at fs/btrfs/extent-tree.c:5648 btrfs_alloc_free_block+0x14e/0x357 [btrfs]()
[21976.930847] Hardware name: XPS 8300
[21976.930848] Modules linked in: tcp_lp tun btrfs zlib_deflate libcrc32c brd fuse cpufreq_ondemand acpi_cpufreq freq_table mperf ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables ipv6 uinput snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec broadcom tg3 snd_hwdep snd_seq snd_seq_device snd_pcm joydev pcspkr iTCO_wdt iTCO_vendor_support dcdbas serio_raw i2c_i801 snd_timer snd microcode soundcore snd_page_alloc usb_storage i915 drm_kms_helper drm i2c_algo_bit i2c_core video [last unloaded: scsi_wait_scan]
[21976.930872] Pid: 31794, comm: btrfs-endio-wri Tainted: G        W 2.6.39-integration-test-20110526-01+ #2
[21976.930874] Call Trace:
[21976.930880]  [<ffffffff8104df7a>] warn_slowpath_common+0x85/0x9d
[21976.930882]  [<ffffffff8104dfac>] warn_slowpath_null+0x1a/0x1c
[21976.930889]  [<ffffffffa02dfca8>] btrfs_alloc_free_block+0x14e/0x357 [btrfs]
[21976.930898]  [<ffffffffa030a073>] ? map_private_extent_buffer+0xb1/0xd5 [btrfs]
[21976.930904]  [<ffffffffa02d2987>] __btrfs_cow_block+0x102/0x31e [btrfs]
[21976.930909]  [<ffffffffa02d1300>] ? btrfs_set_item_key+0x3/0x20 [btrfs]
[21976.930913]  [<ffffffffa02d2ca7>] btrfs_cow_block+0x104/0x14d [btrfs]
[21976.930919]  [<ffffffffa02d5a87>] btrfs_search_slot+0x162/0x502 [btrfs]
[21976.930926]  [<ffffffffa02e3e66>] btrfs_lookup_file_extent+0x3c/0x3e [btrfs]
[21976.930931]  [<ffffffffa02d2124>] ? btrfs_alloc_path+0x1a/0x2b [btrfs]
[21976.930940]  [<ffffffffa02f9319>] btrfs_drop_extents+0x10e/0x731 [btrfs]
[21976.930943]  [<ffffffff8103cc9e>] ? need_resched+0x23/0x2d
[21976.930946]  [<ffffffff81474da6>] ? _cond_resched+0xe/0x22
[21976.930949]  [<ffffffff8110d58c>] ? slab_pre_alloc_hook.clone.32+0x2d/0x31
[21976.930952]  [<ffffffff8110e0c7>] ? kmem_cache_alloc+0x29/0xf7
[21976.930960]  [<ffffffffa02f09fa>] insert_reserved_file_extent.clone.34+0x70/0x1fc [btrfs]
[21976.930970]  [<ffffffffa03071c9>] ? lock_extent_bits+0x5e/0xa8 [btrfs]
[21976.930978]  [<ffffffffa02f362c>] btrfs_endio_direct_write+0x171/0x29a [btrfs]
[21976.930985]  [<ffffffffa02e6afc>] ? end_workqueue_fn+0xf6/0x10e [btrfs]
[21976.930988]  [<ffffffff81141934>] bio_endio+0x2d/0x2f
[21976.930995]  [<ffffffffa02e6b07>] end_workqueue_fn+0x101/0x10e [btrfs]
[21976.931005]  [<ffffffffa0310951>] worker_loop+0x193/0x4ca [btrfs]
[21976.931014]  [<ffffffffa03107be>] ? btrfs_queue_worker+0x214/0x214 [btrfs]
[21976.931016]  [<ffffffff81068dce>] kthread+0x82/0x8a
[21976.931019]  [<ffffffff8147db64>] kernel_thread_helper+0x4/0x10
[21976.931021]  [<ffffffff81068d4c>] ? kthread_worker_fn+0x14b/0x14b
[21976.931023]  [<ffffffff8147db60>] ? gs_change+0x13/0x13
[21976.931025] ---[ end trace abb147a5624a0a29 ]---
[21983.399883] ------------[ cut here ]------------
[21983.399906] WARNING: at fs/btrfs/extent-tree.c:3832 btrfs_free_block_groups+0x13a/0x228 [btrfs]()
[21983.399910] Hardware name: XPS 8300
[21983.399912] Modules linked in: tcp_lp tun btrfs zlib_deflate libcrc32c brd fuse cpufreq_ondemand acpi_cpufreq freq_table mperf ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables ipv6 uinput snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec broadcom tg3 snd_hwdep snd_seq snd_seq_device snd_pcm joydev pcspkr iTCO_wdt iTCO_vendor_support dcdbas serio_raw i2c_i801 snd_timer snd microcode soundcore snd_page_alloc usb_storage i915 drm_kms_helper drm i2c_algo_bit i2c_core video [last unloaded: scsi_wait_scan]
[21983.399958] Pid: 31847, comm: umount Tainted: G        W 2.6.39-integration-test-20110526-01+ #2
[21983.399961] Call Trace:
[21983.399969]  [<ffffffff8104df7a>] warn_slowpath_common+0x85/0x9d
[21983.399975]  [<ffffffff8104dfac>] warn_slowpath_null+0x1a/0x1c
[21983.399989]  [<ffffffffa02e0a2b>] btrfs_free_block_groups+0x13a/0x228 [btrfs]
[21983.400006]  [<ffffffffa02e975a>] close_ctree+0x1b2/0x35e [btrfs]
[21983.400011]  [<ffffffff8112eebb>] ? evict+0x10c/0x115
[21983.400016]  [<ffffffff8103cc9e>] ? need_resched+0x23/0x2d
[21983.400021]  [<ffffffff8103ccb6>] ? should_resched+0xe/0x2e
[21983.400025]  [<ffffffff81474da6>] ? _cond_resched+0xe/0x22
[21983.400029]  [<ffffffff814759b1>] ? down_write+0x29/0x49
[21983.400039]  [<ffffffffa02cfa1e>] btrfs_put_super+0x1d/0x2c [btrfs]
[21983.400044]  [<ffffffff8111c9d4>] generic_shutdown_super+0x74/0xe9
[21983.400048]  [<ffffffff8111cac9>] kill_anon_super+0x16/0x50
[21983.400052]  [<ffffffff8111ccfc>] deactivate_locked_super+0x26/0x4b
[21983.400056]  [<ffffffff8111d4ee>] deactivate_super+0x3a/0x3f
[21983.400061]  [<ffffffff81132732>] mntput_no_expire+0xd0/0xd5
[21983.400065]  [<ffffffff811333b8>] sys_umount+0x2dc/0x30a
[21983.400069]  [<ffffffff8112399e>] ? path_put+0x22/0x27
[21983.400074]  [<ffffffff8147ca42>] system_call_fastpath+0x16/0x1b
[21983.400077] ---[ end trace abb147a5624a0a2a ]---
[21983.400079] ------------[ cut here ]------------
[21983.400092] WARNING: at fs/btrfs/extent-tree.c:3833 btrfs_free_block_groups+0x155/0x228 [btrfs]()
[21983.400095] Hardware name: XPS 8300
[21983.400097] Modules linked in: tcp_lp tun btrfs zlib_deflate libcrc32c brd fuse cpufreq_ondemand acpi_cpufreq freq_table mperf ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables ipv6 uinput snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec broadcom tg3 snd_hwdep snd_seq snd_seq_device snd_pcm joydev pcspkr iTCO_wdt iTCO_vendor_support dcdbas serio_raw i2c_i801 snd_timer snd microcode soundcore snd_page_alloc usb_storage i915 drm_kms_helper drm i2c_algo_bit i2c_core video [last unloaded: scsi_wait_scan]
[21983.400136] Pid: 31847, comm: umount Tainted: G        W 2.6.39-integration-test-20110526-01+ #2
[21983.400139] Call Trace:
[21983.400143]  [<ffffffff8104df7a>] warn_slowpath_common+0x85/0x9d
[21983.400148]  [<ffffffff8104dfac>] warn_slowpath_null+0x1a/0x1c
[21983.400160]  [<ffffffffa02e0a46>] btrfs_free_block_groups+0x155/0x228 [btrfs]
[21983.400176]  [<ffffffffa02e975a>] close_ctree+0x1b2/0x35e [btrfs]
[21983.400179]  [<ffffffff8112eebb>] ? evict+0x10c/0x115
[21983.400184]  [<ffffffff8103cc9e>] ? need_resched+0x23/0x2d
[21983.400188]  [<ffffffff8103ccb6>] ? should_resched+0xe/0x2e
[21983.400191]  [<ffffffff81474da6>] ? _cond_resched+0xe/0x22
[21983.400195]  [<ffffffff814759b1>] ? down_write+0x29/0x49
[21983.400204]  [<ffffffffa02cfa1e>] btrfs_put_super+0x1d/0x2c [btrfs]
[21983.400209]  [<ffffffff8111c9d4>] generic_shutdown_super+0x74/0xe9
[21983.400213]  [<ffffffff8111cac9>] kill_anon_super+0x16/0x50
[21983.400216]  [<ffffffff8111ccfc>] deactivate_locked_super+0x26/0x4b
[21983.400220]  [<ffffffff8111d4ee>] deactivate_super+0x3a/0x3f
[21983.400225]  [<ffffffff81132732>] mntput_no_expire+0xd0/0xd5
[21983.400229]  [<ffffffff811333b8>] sys_umount+0x2dc/0x30a
[21983.400232]  [<ffffffff8112399e>] ? path_put+0x22/0x27
[21983.400237]  [<ffffffff8147ca42>] system_call_fastpath+0x16/0x1b
[21983.400240] ---[ end trace abb147a5624a0a2b ]---
[21983.400242] ------------[ cut here ]------------
[21983.400254] WARNING: at fs/btrfs/extent-tree.c:6846 btrfs_free_block_groups+0x1e6/0x228 [btrfs]()
[21983.400257] Hardware name: XPS 8300
[21983.400259] Modules linked in: tcp_lp tun btrfs zlib_deflate libcrc32c brd fuse cpufreq_ondemand acpi_cpufreq freq_table mperf ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables ipv6 uinput snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec broadcom tg3 snd_hwdep snd_seq snd_seq_device snd_pcm joydev pcspkr iTCO_wdt iTCO_vendor_support dcdbas serio_raw i2c_i801 snd_timer snd microcode soundcore snd_page_alloc usb_storage i915 drm_kms_helper drm i2c_algo_bit i2c_core video [last unloaded: scsi_wait_scan]
[21983.400298] Pid: 31847, comm: umount Tainted: G        W 2.6.39-integration-test-20110526-01+ #2
[21983.400300] Call Trace:
[21983.400305]  [<ffffffff8104df7a>] warn_slowpath_common+0x85/0x9d
[21983.400317]  [<ffffffffa02e0af5>] ? btrfs_free_block_groups+0x204/0x228 [btrfs]
[21983.400322]  [<ffffffff8104dfac>] warn_slowpath_null+0x1a/0x1c
[21983.400334]  [<ffffffffa02e0ad7>] btrfs_free_block_groups+0x1e6/0x228 [btrfs]
[21983.400349]  [<ffffffffa02e975a>] close_ctree+0x1b2/0x35e [btrfs]
[21983.400352]  [<ffffffff8112eebb>] ? evict+0x10c/0x115
[21983.400356]  [<ffffffff8103cc9e>] ? need_resched+0x23/0x2d
[21983.400360]  [<ffffffff8103ccb6>] ? should_resched+0xe/0x2e
[21983.400364]  [<ffffffff81474da6>] ? _cond_resched+0xe/0x22
[21983.400367]  [<ffffffff814759b1>] ? down_write+0x29/0x49
[21983.400377]  [<ffffffffa02cfa1e>] btrfs_put_super+0x1d/0x2c [btrfs]
[21983.400381]  [<ffffffff8111c9d4>] generic_shutdown_super+0x74/0xe9
[21983.400385]  [<ffffffff8111cac9>] kill_anon_super+0x16/0x50
[21983.400389]  [<ffffffff8111ccfc>] deactivate_locked_super+0x26/0x4b
[21983.400392]  [<ffffffff8111d4ee>] deactivate_super+0x3a/0x3f
[21983.400397]  [<ffffffff81132732>] mntput_no_expire+0xd0/0xd5
[21983.400401]  [<ffffffff811333b8>] sys_umount+0x2dc/0x30a
[21983.400404]  [<ffffffff8112399e>] ? path_put+0x22/0x27
[21983.400409]  [<ffffffff8147ca42>] system_call_fastpath+0x16/0x1b
[21983.400412] ---[ end trace abb147a5624a0a2c ]---

Stack dumps for the hang
------------------------

[73934.130640] SysRq : Show Blocked State
[73934.130644]   task                        PC stack   pid father
[73934.130676] btrfs-transacti D ffff8801a4a0b440     0  6769      2 0x00000080
[73934.130679]  ffff88011f78bd60 0000000000000046 0000000000000000 ffff880100000001
[73934.130682]  0000000000013a80 0000000000013a80 0000000000013a80 ffff8801a21a0000
[73934.130684]  0000000000013a80 ffff88011f78bfd8 0000000000013a80 0000000000013a80
[73934.130687] Call Trace:
[73934.130692]  [<ffffffff8106953e>] ? prepare_to_wait+0x6c/0x79
[73934.130704]  [<ffffffffa02eb098>] wait_for_commit.clone.14+0x90/0xd5 [btrfs]
[73934.130706]  [<ffffffff810692ab>] ? wake_up_bit+0x2a/0x2a
[73934.130714]  [<ffffffffa02ebf1c>] btrfs_commit_transaction+0x102/0x693 [btrfs]
[73934.130721]  [<ffffffffa02eb816>] ? join_transaction.clone.20+0x17b/0x186 [btrfs]
[73934.130723]  [<ffffffff810692ab>] ? wake_up_bit+0x2a/0x2a
[73934.130730]  [<ffffffffa02e6772>] transaction_kthread+0x17a/0x22f [btrfs]
[73934.130736]  [<ffffffffa02e65f8>] ? btrfs_congested_fn+0x8c/0x8c [btrfs]
[73934.130738]  [<ffffffff81068dce>] kthread+0x82/0x8a
[73934.130742]  [<ffffffff8147db64>] kernel_thread_helper+0x4/0x10
[73934.130743]  [<ffffffff81068d4c>] ? kthread_worker_fn+0x14b/0x14b
[73934.130745]  [<ffffffff8147db60>] ? gs_change+0x13/0x13
[73934.130747] flush-btrfs-630 D 00000001046677f8     0  6778      2 0x00000080
[73934.130749]  ffff88012031fb10 0000000000000046 ffff88012031fa70 ffff880100000000
[73934.130751]  0000000000013a80 0000000000013a80 0000000000013a80 ffff8801a5c68000
[73934.130754]  0000000000013a80 ffff88012031ffd8 0000000000013a80 0000000000013a80
[73934.130756] Call Trace:
[73934.130759]  [<ffffffff814750a4>] schedule_timeout+0x36/0xe3
[73934.130761]  [<ffffffff8107b6c2>] ? arch_local_irq_save+0x18/0x1e
[73934.130763]  [<ffffffff814762bf>] ? _raw_spin_unlock_irqrestore+0x17/0x19
[73934.130765]  [<ffffffff8106953e>] ? prepare_to_wait+0x6c/0x79
[73934.130771]  [<ffffffffa02ec0dd>] btrfs_commit_transaction+0x2c3/0x693 [btrfs]
[73934.130773]  [<ffffffff810692ab>] ? wake_up_bit+0x2a/0x2a
[73934.130781]  [<ffffffffa02f58ba>] btrfs_write_inode+0xa0/0xa9 [btrfs]
[73934.130784]  [<ffffffff81138d78>] writeback_single_inode+0x125/0x1bf
[73934.130786]  [<ffffffff81139055>] writeback_sb_inodes+0xce/0x160
[73934.130788]  [<ffffffff81139d68>] wb_writeback+0x257/0x3a7
[73934.130790]  [<ffffffff81139f40>] wb_do_writeback+0x88/0x1a0
[73934.130792]  [<ffffffff8105b0a1>] ? run_timer_softirq+0x298/0x298
[73934.130794]  [<ffffffff8113a0e3>] bdi_writeback_thread+0x8b/0x20c
[73934.130796]  [<ffffffff8113a058>] ? wb_do_writeback+0x1a0/0x1a0
[73934.130798]  [<ffffffff81068dce>] kthread+0x82/0x8a
[73934.130800]  [<ffffffff8147db64>] kernel_thread_helper+0x4/0x10
[73934.130802]  [<ffffffff81068d4c>] ? kthread_worker_fn+0x14b/0x14b
[73934.130804]  [<ffffffff8147db60>] ? gs_change+0x13/0x13
[73934.130805] fsstress        D 0000000102eb08dd     0  6808      1 0x00000084
[73934.130807]  ffff88011d941d48 0000000000000086 0000000000000000 0000000000000400
[73934.130809]  0000000000013a80 0000000000013a80 0000000000013a80 ffff88018c3f5c40
[73934.130812]  0000000000013a80 ffff88011d941fd8 0000000000013a80 0000000000013a80
[73934.130814] Call Trace:
[73934.130816]  [<ffffffff8103dadf>] ? resched_task+0x48/0x72
[73934.130818]  [<ffffffff814750a4>] schedule_timeout+0x36/0xe3
[73934.130820]  [<ffffffff814762bf>] ? _raw_spin_unlock_irqrestore+0x17/0x19
[73934.130822]  [<ffffffff8103cc9e>] ? need_resched+0x23/0x2d
[73934.130824]  [<ffffffff81474e67>] wait_for_common+0xad/0x102
[73934.130826]  [<ffffffff81046df8>] ? try_to_wake_up+0x226/0x226
[73934.130828]  [<ffffffff81053dbc>] ? local_bh_enable_ip+0xe/0x10
[73934.130830]  [<ffffffff8113cf5c>] ? __sync_filesystem+0x7a/0x7a
[73934.130832]  [<ffffffff81474f74>] wait_for_completion+0x1d/0x1f
[73934.130834]  [<ffffffff81139717>] sync_inodes_sb+0x91/0x187
[73934.130835]  [<ffffffff8113cf5c>] ? __sync_filesystem+0x7a/0x7a
[73934.130837]  [<ffffffff8113cf29>] __sync_filesystem+0x47/0x7a
[73934.130839]  [<ffffffff8113cf72>] sync_one_sb+0x16/0x18
[73934.130841]  [<ffffffff8111d632>] iterate_supers+0x6d/0xc4
[73934.130843]  [<ffffffff8113cea7>] sync_filesystems+0x20/0x22
[73934.130845]  [<ffffffff8113cfe5>] sys_sync+0x21/0x33
[73934.130847]  [<ffffffff8147ca42>] system_call_fastpath+0x16/0x1b
[73934.130848] fsstress        D 0000000102eb08dd     0  6809      1 0x00000084
[73934.130850]  ffff88011f07fa58 0000000000000082 ffff88010b9bf058 0000000100000001
[73934.130853]  0000000000013a80 0000000000013a80 0000000000013a80 ffff88018c3f2e20
[73934.130855]  0000000000013a80 ffff88011f07ffd8 0000000000013a80 0000000000013a80
[73934.130857] Call Trace:
[73934.130859]  [<ffffffff811ea828>] ? avc_has_perm_flags+0x6c/0x81
[73934.130861]  [<ffffffff814750a4>] schedule_timeout+0x36/0xe3
[73934.130863]  [<ffffffff81476256>] ? _raw_spin_lock+0xe/0x10
[73934.130865]  [<ffffffff8103e624>] ? task_rq_lock+0x40/0x72
[73934.130867]  [<ffffffff814762bf>] ? _raw_spin_unlock_irqrestore+0x17/0x19
[73934.130869]  [<ffffffff8103cc9e>] ? need_resched+0x23/0x2d
[73934.130870]  [<ffffffff81474e67>] wait_for_common+0xad/0x102
[73934.130872]  [<ffffffff81046df8>] ? try_to_wake_up+0x226/0x226
[73934.130874]  [<ffffffff81053dbc>] ? local_bh_enable_ip+0xe/0x10
[73934.130876]  [<ffffffff81474f74>] wait_for_completion+0x1d/0x1f
[73934.130877]  [<ffffffff811395bd>] writeback_inodes_sb_nr+0x76/0x7d
[73934.130880]  [<ffffffff81139670>] writeback_inodes_sb_nr_if_idle+0x41/0x57
[73934.130885]  [<ffffffffa02d9ec4>] shrink_delalloc.clone.46+0xb2/0x155 [btrfs]
[73934.130888]  [<ffffffff811f560f>] ? sidtab_context_to_sid+0x5a/0x12c
[73934.130893]  [<ffffffffa02da060>] reserve_metadata_bytes.clone.47+0xf9/0x1b3 [btrfs]
[73934.130899]  [<ffffffffa02dcc09>] btrfs_block_rsv_add+0x2c/0x4f [btrfs]
[73934.130901]  [<ffffffff8103ccb6>] ? should_resched+0xe/0x2e
[73934.130907]  [<ffffffffa02dce32>] btrfs_trans_reserve_metadata+0x4f/0x74 [btrfs]
[73934.130914]  [<ffffffffa02ec899>] start_transaction+0x190/0x24f [btrfs]
[73934.130921]  [<ffffffffa02ecc7b>] btrfs_start_transaction+0x13/0x15 [btrfs]
[73934.130928]  [<ffffffffa02f6e04>] btrfs_mkdir+0x46/0x1e5 [btrfs]
[73934.130931]  [<ffffffff8112520a>] vfs_mkdir+0x63/0x9f
[73934.130933]  [<ffffffff81127373>] sys_mkdirat+0x96/0xe7
[73934.130934]  [<ffffffff8112399e>] ? path_put+0x22/0x27
[73934.130937]  [<ffffffff810988fb>] ? audit_syscall_entry+0x11c/0x148
[73934.130938]  [<ffffffff811273dc>] sys_mkdir+0x18/0x1a
[73934.130940]  [<ffffffff8147ca42>] system_call_fastpath+0x16/0x1b
[73934.130942] updatedb        D 0000000102f9f23b     0  7525   7519 0x00000080
[73934.130944]  ffff88011ee61e28 0000000000000086 ffff88011ee61f28 ffff880100000000
[73934.130946]  0000000000013a80 0000000000013a80 0000000000013a80 ffff8801a5ccae20
[73934.130949]  0000000000013a80 ffff88011ee61fd8 0000000000013a80 0000000000013a80
[73934.130951] Call Trace:
[73934.130953]  [<ffffffff81475660>] __mutex_lock_common.clone.5+0x12f/0x196
[73934.130955]  [<ffffffff81129280>] ? filldir64+0xd5/0xd5
[73934.130957]  [<ffffffff814756ef>] __mutex_lock_killable_slowpath+0x13/0x15
[73934.130960]  [<ffffffff8106bd38>] __mutex_fastpath_lock_retval+0x18/0x1a
[73934.130961]  [<ffffffff81475471>] mutex_lock_killable+0x38/0x54
[73934.130963]  [<ffffffff81129460>] vfs_readdir+0x56/0xac
[73934.130965]  [<ffffffff8112959f>] sys_getdents+0x81/0xd1
[73934.130967]  [<ffffffff8147ca42>] system_call_fastpath+0x16/0x1b
[73934.130970] sync            D 0000000104667813     0  8162   1930 0x00000080
[73934.130972]  ffff880190491d48 0000000000000082 0000000000000000 0000000000000000
[73934.130974]  0000000000013a80 0000000000013a80 0000000000013a80 ffff88015abe0000
[73934.130976]  0000000000013a80 ffff880190491fd8 0000000000013a80 0000000000013a80
[73934.130978] Call Trace:
[73934.130980]  [<ffffffff814750a4>] schedule_timeout+0x36/0xe3
[73934.130982]  [<ffffffff814762bf>] ? _raw_spin_unlock_irqrestore+0x17/0x19
[73934.130984]  [<ffffffff8103cc9e>] ? need_resched+0x23/0x2d
[73934.130985]  [<ffffffff81474e67>] wait_for_common+0xad/0x102
[73934.130987]  [<ffffffff81046df8>] ? try_to_wake_up+0x226/0x226
[73934.130989]  [<ffffffff81053dbc>] ? local_bh_enable_ip+0xe/0x10
[73934.130991]  [<ffffffff8113cf5c>] ? __sync_filesystem+0x7a/0x7a
[73934.130993]  [<ffffffff81474f74>] wait_for_completion+0x1d/0x1f
[73934.130994]  [<ffffffff811395bd>] writeback_inodes_sb_nr+0x76/0x7d
[73934.130996]  [<ffffffff811395e6>] writeback_inodes_sb+0x22/0x24
[73934.130998]  [<ffffffff8113cf33>] __sync_filesystem+0x51/0x7a
[73934.131000]  [<ffffffff8113cf72>] sync_one_sb+0x16/0x18
[73934.131002]  [<ffffffff8111d632>] iterate_supers+0x6d/0xc4
[73934.131004]  [<ffffffff8113cea7>] sync_filesystems+0x20/0x22
[73934.131005]  [<ffffffff8113cfdb>] sys_sync+0x17/0x33
[73934.131007]  [<ffffffff8147ca42>] system_call_fastpath+0x16/0x1b

I've tried to reproduce myself, but the fsstress utility (taken from latest LTP suite) crashes sometimes and I cannot take it as a proper reproduction. Can you point me to the exact version you used?

(But no warning or hang observed, on top of 3.0-rc1 + cmason/for-linus)

this is minimal size possible, 256MB

5644 ret = block_rsv_use_bytes(block_rsv, blocksize);
5645 if (!ret)
5646 return block_rsv;
5647 if (ret) {

5648 WARN_ON(1);

5649 ret = reserve_metadata_bytes(trans, root, block_rsv, blocksize,
5650 0);

and block_rsv_use_bytes() returns nonzero in case of ENOSPC.

3829 static void release_global_block_rsv(struct btrfs_fs_info *fs_info) 3830 {
3831 block_rsv_release_bytes(&fs_info->global_block_rsv, NULL, (u64)-1);

3832 WARN_ON(fs_info->delalloc_block_rsv.size > 0);

3833 WARN_ON(fs_info->delalloc_block_rsv.reserved > 0);

in release_global_block_rsv(block_rsv, NULL, num_bytes = (u64)-1):

3543 if (num_bytes == (u64)-1)
3544 num_bytes = block_rsv->size;
3545 block_rsv->size -= num_bytes;

now block_rsv->size is 0, right? but why did the warn trigger after return from the call, there is no other assignment in this function. another thread? possible.

3546 if (block_rsv->reserved >= block_rsv->size) {
3547 num_bytes = block_rsv->reserved - block_rsv->size;
3548 block_rsv->reserved = block_rsv->size;

reserved is now 0, but changed later in the func

3549 block_rsv->full = 1;
3550 } else {
3551 num_bytes = 0;
3552 }

->reserved field of block_rsv

6844 if (space_info->bytes_pinned > 0 ||
6845 space_info->bytes_reserved > 0) {
6846 WARN_ON(1);
6847 dump_space_info(space_info, 0, 0);
6848 }

the hang seems serious, it's stuck at fs shutdown under an ENOSPC condition when several operations are in progress, see the stacks for more (background writeback, sync, mkdir, readdir).

I didn't go further in pre-analysis, obviously the traces have one in common:
block reserves and ENOSPC.

david

The LTP version does not compile properly:

make[4]: Entering directory `/home/ahunter/Desktop/Projects/ltp/ltp-full-20110228/testcases/kernel/fs/fsstress'
gcc -g -O2 -g -O2 -fno-strict-aliasing -pipe -Wall -DNO_XFS -I/home/ahunter/Desktop/Projects/ltp/ltp-full-20110228/testcases/kernel/fs/fsstress -D_LARGEFILE64_SOURCE -D_GNU_SOURCE -Wno-error -I../../../../include -I../../../../include -L../../../../lib fsstress.c -o fsstress
fsstress.c: In function 'dread_f':
fsstress.c:1829:2: warning: implicit declaration of function 'memalign'
fsstress.c:1829:6: warning: assignment makes pointer from integer without a cast
fsstress.c: In function 'dwrite_f':
fsstress.c:1912:6: warning: assignment makes pointer from integer without a cast fsstress.c:1844:17: warning: 'diob.d_miniosz' may be used uninitialized in this function fsstress.c:1844:17: warning: 'diob.d_maxiosz' may be used uninitialized in this function fsstress.c:1844:17: warning: 'diob.d_mem' may be used uninitialized in this function fsstress.c: In function 'dread_f':
fsstress.c:1750:17: warning: 'diob.d_miniosz' may be used uninitialized in this function fsstress.c:1750:17: warning: 'diob.d_maxiosz' may be used uninitialized in this function fsstress.c:1750:17: warning: 'diob.d_mem' may be used uninitialized in this function

I hacked a couple of changes but I need to check them before mailing to the ltp-list:

From: Adrian Hunter <[email protected]>
Date: Wed, 1 Jun 2011 13:01:48 +0300
Subject: [PATCH] fsstress: quick fix for compile errors

---
 testcases/kernel/fs/fsstress/fsstress.c |    2 ++
 testcases/kernel/fs/fsstress/global.h   |    1 +
 2 files changed, 3 insertions(+), 0 deletions(-)

index e3b48ea..83c23ed 100644
@@ -1757,6 +1757,7 @@ dread_f(int opno, long r)
 	struct stat64	stb;
 	int		v;
 
+	memset(&diob, 0, sizeof(struct dioattr));
 	init_pathname(&f);
 	if (!get_fname(FT_REGFILE, r, &f, NULL, NULL, &v)) {
 		if (v)

@@ -1851,6 +1852,7 @@ dwrite_f(int opno, long r)
 	struct stat64	stb;
 	int		v;
 
+	memset(&diob, 0, sizeof(struct dioattr));
 	init_pathname(&f);
 	if (!get_fname(FT_REGFILE, r, &f, NULL, NULL, &v)) {
 		if (v)

index f788395..5ab5d56 100644
@@ -58,6 +58,7 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <unistd.h>
+#include <malloc.h>
 
 #ifndef O_DIRECT
 #define O_DIRECT 040000

1.7.4.4

I will try it tonight.

In fact there is already a fix here:

http://sourceforge.net/mailarchive/message.php?msg_id=27212868

No improvement on 3.0-rc1+ (commit 5c6cce92bc8aee751aafe82c5d9caf7553226a3d).

Logs follow:

Warnings
--------

[ 2857.023360] WARNING: at fs/btrfs/extent-tree.c:5648 btrfs_alloc_free_block+0x14e/0x357 [btrfs]()
[ 2857.023364] Hardware name: XPS 8300
[ 2857.023367] Modules linked in: tun btrfs zlib_deflate libcrc32c brd fuse cpufreq_ondemand acpi_cpufreq freq_table mperf ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables ipv6 uinput snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec snd_hwdep snd_seq snd_seq_device broadcom snd_pcm snd_timer snd tg3 iTCO_wdt serio_raw dcdbas iTCO_vendor_support microcode soundcore pcspkr snd_page_alloc i2c_i801 joydev usb_storage i915 drm_kms_helper drm i2c_algo_bit i2c_core video [last unloaded: scsi_wait_scan]
[ 2857.023431] Pid: 8809, comm: btrfs-endio-wri Not tainted 3.0.0-rc1-work-2011-06-01-01+ #11
[ 2857.023435] Call Trace:
[ 2857.023461]  [<ffffffff8104db2e>] warn_slowpath_common+0x85/0x9d
[ 2857.023471]  [<ffffffff8104db60>] warn_slowpath_null+0x1a/0x1c
[ 2857.023494]  [<ffffffffa029cc98>] btrfs_alloc_free_block+0x14e/0x357 [btrfs]
[ 2857.023526]  [<ffffffffa02c75bb>] ? map_private_extent_buffer+0xb1/0xd5 [btrfs]
[ 2857.023547]  [<ffffffffa028f99f>] __btrfs_cow_block+0x102/0x31e [btrfs]
[ 2857.023565]  [<ffffffffa028e500>] ? unlock_up+0xd9/0xe4 [btrfs]
[ 2857.023585]  [<ffffffffa028fcbf>] btrfs_cow_block+0x104/0x14e [btrfs]
[ 2857.023604]  [<ffffffffa0292aa0>] btrfs_search_slot+0x162/0x502 [btrfs]
[ 2857.023625]  [<ffffffffa0293d46>] btrfs_insert_empty_items+0x6a/0xba [btrfs]
[ 2857.023636]  [<ffffffff81110422>] ? kmem_cache_alloc+0x29/0xf7
[ 2857.023658]  [<ffffffffa02adb39>] insert_reserved_file_extent.clone.34+0xad/0x1fc [btrfs]
[ 2857.023680]  [<ffffffffa02c4708>] ? lock_extent_bits+0x5e/0xa8 [btrfs]
[ 2857.023701]  [<ffffffffa02b0772>] btrfs_endio_direct_write+0x171/0x29a [btrfs]
[ 2857.023719]  [<ffffffffa02a3afa>] ? end_workqueue_fn+0xf6/0x10e [btrfs]
[ 2857.023728]  [<ffffffff81143d1c>] bio_endio+0x2d/0x2f
[ 2857.023744]  [<ffffffffa02a3b05>] end_workqueue_fn+0x101/0x10e [btrfs]
[ 2857.023766]  [<ffffffffa02cde4d>] worker_loop+0x193/0x4ca [btrfs]
[ 2857.023786]  [<ffffffffa02cdcba>] ? btrfs_queue_worker+0x214/0x214 [btrfs]
[ 2857.023793]  [<ffffffff81068f4e>] kthread+0x82/0x8a
[ 2857.023801]  [<ffffffff81483664>] kernel_thread_helper+0x4/0x10
[ 2857.023807]  [<ffffffff81068ecc>] ? kthread_worker_fn+0x14b/0x14b
[ 2857.023813]  [<ffffffff81483660>] ? gs_change+0x13/0x13
[ 2857.023818] ---[ end trace 11fa90e2fd0455a5 ]---
[ 2857.023835] ------------[ cut here ]------------
[ 2857.023851] WARNING: at fs/btrfs/extent-tree.c:5648 btrfs_alloc_free_block+0x14e/0x357 [btrfs]()
[ 2857.023856] Hardware name: XPS 8300
[ 2857.023859] Modules linked in: tun btrfs zlib_deflate libcrc32c brd fuse cpufreq_ondemand acpi_cpufreq freq_table mperf ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables ipv6 uinput snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec snd_hwdep snd_seq snd_seq_device broadcom snd_pcm snd_timer snd tg3 iTCO_wdt serio_raw dcdbas iTCO_vendor_support microcode soundcore pcspkr snd_page_alloc i2c_i801 joydev usb_storage i915 drm_kms_helper drm i2c_algo_bit i2c_core video [last unloaded: scsi_wait_scan]
[ 2857.023948] Pid: 8833, comm: btrfs-endio-wri Tainted: G        W 3.0.0-rc1-work-2011-06-01-01+ #11
[ 2857.023953] Call Trace:
[ 2857.023959]  [<ffffffff8104db2e>] warn_slowpath_common+0x85/0x9d
[ 2857.023966]  [<ffffffff8104db60>] warn_slowpath_null+0x1a/0x1c
[ 2857.023982]  [<ffffffffa029cc98>] btrfs_alloc_free_block+0x14e/0x357 [btrfs]
[ 2857.023989]  [<ffffffff81041344>] ? update_stats_wait_end.clone.74+0x6a/0xad
[ 2857.024002]  [<ffffffffa028f99f>] __btrfs_cow_block+0x102/0x31e [btrfs]
[ 2857.024015]  [<ffffffffa028e500>] ? unlock_up+0xd9/0xe4 [btrfs]
[ 2857.024028]  [<ffffffffa028fcbf>] btrfs_cow_block+0x104/0x14e [btrfs]
[ 2857.024049]  [<ffffffffa02d295e>] ? btrfs_spin_on_block+0x55/0x55 [btrfs]
[ 2857.024062]  [<ffffffffa0292aa0>] btrfs_search_slot+0x162/0x502 [btrfs]
[ 2857.024068]  [<ffffffff8110f8e8>] ? slab_pre_alloc_hook.clone.33+0x2d/0x31
[ 2857.024086]  [<ffffffffa02a0e16>] btrfs_lookup_file_extent+0x3c/0x3e [btrfs]
[ 2857.024099]  [<ffffffffa028f13c>] ? btrfs_alloc_path+0x1a/0x2b [btrfs]
[ 2857.024119]  [<ffffffffa02b684d>] btrfs_drop_extents+0x10e/0x731 [btrfs]
[ 2857.024127]  [<ffffffff8103d050>] ? need_resched+0x23/0x2d
[ 2857.024134]  [<ffffffff8147a88e>] ? _cond_resched+0xe/0x22
[ 2857.024140]  [<ffffffff8110f8e8>] ? slab_pre_alloc_hook.clone.33+0x2d/0x31
[ 2857.024146]  [<ffffffff81110422>] ? kmem_cache_alloc+0x29/0xf7
[ 2857.024165]  [<ffffffffa02adafc>] insert_reserved_file_extent.clone.34+0x70/0x1fc [btrfs]
[ 2857.024187]  [<ffffffffa02c4708>] ? lock_extent_bits+0x5e/0xa8 [btrfs]
[ 2857.024206]  [<ffffffffa02b0772>] btrfs_endio_direct_write+0x171/0x29a [btrfs]
[ 2857.024225]  [<ffffffffa02a3afa>] ? end_workqueue_fn+0xf6/0x10e [btrfs]
[ 2857.024232]  [<ffffffff81143d1c>] bio_endio+0x2d/0x2f
[ 2857.024248]  [<ffffffffa02a3b05>] end_workqueue_fn+0x101/0x10e [btrfs]
[ 2857.024269]  [<ffffffffa02cde4d>] worker_loop+0x193/0x4ca [btrfs]
[ 2857.024289]  [<ffffffffa02cdcba>] ? btrfs_queue_worker+0x214/0x214 [btrfs]
[ 2857.024295]  [<ffffffff81068f4e>] kthread+0x82/0x8a
[ 2857.024301]  [<ffffffff81483664>] kernel_thread_helper+0x4/0x10
[ 2857.024308]  [<ffffffff81068ecc>] ? kthread_worker_fn+0x14b/0x14b
[ 2857.024314]  [<ffffffff81483660>] ? gs_change+0x13/0x13
[ 2857.024318] ---[ end trace 11fa90e2fd0455a6 ]---
[ 2857.024374] ------------[ cut here ]------------
[ 2857.024390] WARNING: at fs/btrfs/extent-tree.c:5648 btrfs_alloc_free_block+0x14e/0x357 [btrfs]()
[ 2857.024395] Hardware name: XPS 8300
[ 2857.024398] Modules linked in: tun btrfs zlib_deflate libcrc32c brd fuse cpufreq_ondemand acpi_cpufreq freq_table mperf ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables ipv6 uinput snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec snd_hwdep snd_seq snd_seq_device broadcom snd_pcm snd_timer snd tg3 iTCO_wdt serio_raw dcdbas iTCO_vendor_support microcode soundcore pcspkr snd_page_alloc i2c_i801 joydev usb_storage i915 drm_kms_helper drm i2c_algo_bit i2c_core video [last unloaded: scsi_wait_scan]
[ 2857.024483] Pid: 8809, comm: btrfs-endio-wri Tainted: G        W 3.0.0-rc1-work-2011-06-01-01+ #11
[ 2857.024487] Call Trace:
[ 2857.024494]  [<ffffffff8104db2e>] warn_slowpath_common+0x85/0x9d
[ 2857.024501]  [<ffffffff8104db60>] warn_slowpath_null+0x1a/0x1c
[ 2857.024517]  [<ffffffffa029cc98>] btrfs_alloc_free_block+0x14e/0x357 [btrfs]
[ 2857.024538]  [<ffffffffa02c397e>] ? merge_state+0xa6/0x11a [btrfs]
[ 2857.024546]  [<ffffffff8122aef8>] ? rb_insert_color+0xb8/0xe1
[ 2857.024559]  [<ffffffffa028f99f>] __btrfs_cow_block+0x102/0x31e [btrfs]
[ 2857.024579]  [<ffffffffa02c7693>] ? unmap_extent_buffer+0xe/0x10 [btrfs]
[ 2857.024592]  [<ffffffffa028e500>] ? unlock_up+0xd9/0xe4 [btrfs]
[ 2857.024604]  [<ffffffffa028fcbf>] btrfs_cow_block+0x104/0x14e [btrfs]
[ 2857.024617]  [<ffffffffa02920b4>] push_leaf_right+0xc4/0x142 [btrfs]
[ 2857.024635]  [<ffffffffa02c764b>] ? map_extent_buffer+0x6c/0xa6 [btrfs]
[ 2857.024649]  [<ffffffffa0292267>] split_leaf+0x84/0x53c [btrfs]
[ 2857.024661]  [<ffffffffa028e297>] ? btrfs_item_offset_nr+0x19/0x1b [btrfs]
[ 2857.024673]  [<ffffffffa028e569>] ? leaf_space_used+0x5e/0x86 [btrfs]
[ 2857.024686]  [<ffffffffa0292d87>] btrfs_search_slot+0x449/0x502 [btrfs]
[ 2857.024700]  [<ffffffffa0293d46>] btrfs_insert_empty_items+0x6a/0xba [btrfs]
[ 2857.024707]  [<ffffffff81110422>] ? kmem_cache_alloc+0x29/0xf7
[ 2857.024727]  [<ffffffffa02adb39>] insert_reserved_file_extent.clone.34+0xad/0x1fc [btrfs]
[ 2857.024747]  [<ffffffffa02c4708>] ? lock_extent_bits+0x5e/0xa8 [btrfs]
[ 2857.024767]  [<ffffffffa02b0772>] btrfs_endio_direct_write+0x171/0x29a [btrfs]
[ 2857.024785]  [<ffffffffa02a3afa>] ? end_workqueue_fn+0xf6/0x10e [btrfs]
[ 2857.024792]  [<ffffffff81143d1c>] bio_endio+0x2d/0x2f
[ 2857.024808]  [<ffffffffa02a3b05>] end_workqueue_fn+0x101/0x10e [btrfs]
[ 2857.024828]  [<ffffffffa02cde4d>] worker_loop+0x193/0x4ca [btrfs]
[ 2857.024848]  [<ffffffffa02cdcba>] ? btrfs_queue_worker+0x214/0x214 [btrfs]
[ 2857.024855]  [<ffffffff81068f4e>] kthread+0x82/0x8a
[ 2857.024861]  [<ffffffff81483664>] kernel_thread_helper+0x4/0x10
[ 2857.024868]  [<ffffffff81068ecc>] ? kthread_worker_fn+0x14b/0x14b
[ 2857.024875]  [<ffffffff81483660>] ? gs_change+0x13/0x13
[ 2857.024879] ---[ end trace 11fa90e2fd0455a7 ]---
[ 2857.024915] ------------[ cut here ]------------
[ 2857.024936] WARNING: at fs/btrfs/extent-tree.c:5648 btrfs_alloc_free_block+0x14e/0x357 [btrfs]()
[ 2857.024941] Hardware name: XPS 8300
[ 2857.024944] Modules linked in: tun btrfs zlib_deflate libcrc32c brd fuse cpufreq_ondemand acpi_cpufreq freq_table mperf ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables ipv6 uinput snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec snd_hwdep snd_seq snd_seq_device broadcom snd_pcm snd_timer snd tg3 iTCO_wdt serio_raw dcdbas iTCO_vendor_support microcode soundcore pcspkr snd_page_alloc i2c_i801 joydev usb_storage i915 drm_kms_helper drm i2c_algo_bit i2c_core video [last unloaded: scsi_wait_scan]
[ 2857.025029] Pid: 8833, comm: btrfs-endio-wri Tainted: G        W 3.0.0-rc1-work-2011-06-01-01+ #11
[ 2857.025034] Call Trace:
[ 2857.025043]  [<ffffffff8104db2e>] warn_slowpath_common+0x85/0x9d
[ 2857.025050]  [<ffffffff8104db60>] warn_slowpath_null+0x1a/0x1c
[ 2857.025066]  [<ffffffffa029cc98>] btrfs_alloc_free_block+0x14e/0x357 [btrfs]
[ 2857.025080]  [<ffffffffa028f99f>] __btrfs_cow_block+0x102/0x31e [btrfs]
[ 2857.025093]  [<ffffffffa028e500>] ? unlock_up+0xd9/0xe4 [btrfs]
[ 2857.025106]  [<ffffffffa028fcbf>] btrfs_cow_block+0x104/0x14e [btrfs]
[ 2857.025120]  [<ffffffffa0292aa0>] btrfs_search_slot+0x162/0x502 [btrfs]
[ 2857.025138]  [<ffffffffa02a0e16>] btrfs_lookup_file_extent+0x3c/0x3e [btrfs]
[ 2857.025150]  [<ffffffffa028f13c>] ? btrfs_alloc_path+0x1a/0x2b [btrfs]
[ 2857.025172]  [<ffffffffa02b684d>] btrfs_drop_extents+0x10e/0x731 [btrfs]
[ 2857.025179]  [<ffffffff8103d050>] ? need_resched+0x23/0x2d
[ 2857.025188]  [<ffffffff8147a88e>] ? _cond_resched+0xe/0x22
[ 2857.025196]  [<ffffffff8110f8e8>] ? slab_pre_alloc_hook.clone.33+0x2d/0x31
[ 2857.025205]  [<ffffffff81110422>] ? kmem_cache_alloc+0x29/0xf7
[ 2857.025231]  [<ffffffffa02adafc>] insert_reserved_file_extent.clone.34+0x70/0x1fc [btrfs]
[ 2857.025255]  [<ffffffffa02c4708>] ? lock_extent_bits+0x5e/0xa8 [btrfs]
[ 2857.025278]  [<ffffffffa02b0772>] btrfs_endio_direct_write+0x171/0x29a [btrfs]
[ 2857.025304]  [<ffffffffa02a3afa>] ? end_workqueue_fn+0xf6/0x10e [btrfs]
[ 2857.025313]  [<ffffffff81143d1c>] bio_endio+0x2d/0x2f
[ 2857.025336]  [<ffffffffa02a3b05>] end_workqueue_fn+0x101/0x10e [btrfs]
[ 2857.025366]  [<ffffffffa02cde4d>] worker_loop+0x193/0x4ca [btrfs]
[ 2857.025387]  [<ffffffffa02cdcba>] ? btrfs_queue_worker+0x214/0x214 [btrfs]
[ 2857.025393]  [<ffffffff81068f4e>] kthread+0x82/0x8a
[ 2857.025400]  [<ffffffff81483664>] kernel_thread_helper+0x4/0x10
[ 2857.025406]  [<ffffffff81068ecc>] ? kthread_worker_fn+0x14b/0x14b
[ 2857.025413]  [<ffffffff81483660>] ? gs_change+0x13/0x13
[ 2857.025417] ---[ end trace 11fa90e2fd0455a8 ]---
[ 2857.025527] ------------[ cut here ]------------
[ 2857.025544] WARNING: at fs/btrfs/extent-tree.c:5648 btrfs_alloc_free_block+0x14e/0x357 [btrfs]()
[ 2857.025549] Hardware name: XPS 8300
[ 2857.025552] Modules linked in: tun btrfs zlib_deflate libcrc32c brd fuse cpufreq_ondemand acpi_cpufreq freq_table mperf ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables ipv6 uinput snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec snd_hwdep snd_seq snd_seq_device broadcom snd_pcm snd_timer snd tg3 iTCO_wdt serio_raw dcdbas iTCO_vendor_support microcode soundcore pcspkr snd_page_alloc i2c_i801 joydev usb_storage i915 drm_kms_helper drm i2c_algo_bit i2c_core video [last unloaded: scsi_wait_scan]
[ 2857.025633] Pid: 8833, comm: btrfs-endio-wri Tainted: G        W 3.0.0-rc1-work-2011-06-01-01+ #11
[ 2857.025638] Call Trace:
[ 2857.025645]  [<ffffffff8104db2e>] warn_slowpath_common+0x85/0x9d
[ 2857.025653]  [<ffffffff8104db60>] warn_slowpath_null+0x1a/0x1c
[ 2857.025668]  [<ffffffffa029cc98>] btrfs_alloc_free_block+0x14e/0x357 [btrfs]
[ 2857.025675]  [<ffffffff81041616>] ? dequeue_task_fair+0x1ca/0x1d9
[ 2857.025688]  [<ffffffffa028f99f>] __btrfs_cow_block+0x102/0x31e [btrfs]
[ 2857.025700]  [<ffffffffa028e500>] ? unlock_up+0xd9/0xe4 [btrfs]
[ 2857.025713]  [<ffffffffa028fcbf>] btrfs_cow_block+0x104/0x14e [btrfs]
[ 2857.025734]  [<ffffffffa02d295e>] ? btrfs_spin_on_block+0x55/0x55 [btrfs]
[ 2857.025754]  [<ffffffffa0292aa0>] btrfs_search_slot+0x162/0x502 [btrfs]
[ 2857.025763]  [<ffffffff8110f8e8>] ? slab_pre_alloc_hook.clone.33+0x2d/0x31
[ 2857.025788]  [<ffffffffa02a0e16>] btrfs_lookup_file_extent+0x3c/0x3e [btrfs]
[ 2857.025803]  [<ffffffffa028f13c>] ? btrfs_alloc_path+0x1a/0x2b [btrfs]
[ 2857.025824]  [<ffffffffa02b684d>] btrfs_drop_extents+0x10e/0x731 [btrfs]
[ 2857.025830]  [<ffffffff8103d050>] ? need_resched+0x23/0x2d
[ 2857.025836]  [<ffffffff8147a88e>] ? _cond_resched+0xe/0x22
[ 2857.025842]  [<ffffffff8110f8e8>] ? slab_pre_alloc_hook.clone.33+0x2d/0x31
[ 2857.025848]  [<ffffffff81110422>] ? kmem_cache_alloc+0x29/0xf7
[ 2857.025867]  [<ffffffffa02adafc>] insert_reserved_file_extent.clone.34+0x70/0x1fc [btrfs]
[ 2857.025889]  [<ffffffffa02c4708>] ? lock_extent_bits+0x5e/0xa8 [btrfs]
[ 2857.025909]  [<ffffffffa02b0772>] btrfs_endio_direct_write+0x171/0x29a [btrfs]
[ 2857.025926]  [<ffffffffa02a3afa>] ? end_workqueue_fn+0xf6/0x10e [btrfs]
[ 2857.025933]  [<ffffffff81143d1c>] bio_endio+0x2d/0x2f
[ 2857.025949]  [<ffffffffa02a3b05>] end_workqueue_fn+0x101/0x10e [btrfs]
[ 2857.025979]  [<ffffffffa02cde4d>] worker_loop+0x193/0x4ca [btrfs]
[ 2857.026006]  [<ffffffffa02cdcba>] ? btrfs_queue_worker+0x214/0x214 [btrfs]
[ 2857.026012]  [<ffffffff81068f4e>] kthread+0x82/0x8a
[ 2857.026018]  [<ffffffff81483664>] kernel_thread_helper+0x4/0x10
[ 2857.026022]  [<ffffffff81068ecc>] ? kthread_worker_fn+0x14b/0x14b
[ 2857.026027]  [<ffffffff81483660>] ? gs_change+0x13/0x13
[ 2857.026030] ---[ end trace 11fa90e2fd0455a9 ]---
[ 2857.026053] ------------[ cut here ]------------
[ 2857.026067] WARNING: at fs/btrfs/extent-tree.c:5648 btrfs_alloc_free_block+0x14e/0x357 [btrfs]()
[ 2857.026070] Hardware name: XPS 8300
[ 2857.026072] Modules linked in: tun btrfs zlib_deflate libcrc32c brd fuse cpufreq_ondemand acpi_cpufreq freq_table mperf ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables ipv6 uinput snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec snd_hwdep snd_seq snd_seq_device broadcom snd_pcm snd_timer snd tg3 iTCO_wdt serio_raw dcdbas iTCO_vendor_support microcode soundcore pcspkr snd_page_alloc i2c_i801 joydev usb_storage i915 drm_kms_helper drm i2c_algo_bit i2c_core video [last unloaded: scsi_wait_scan]
[ 2857.026112] Pid: 8833, comm: btrfs-endio-wri Tainted: G        W 3.0.0-rc1-work-2011-06-01-01+ #11
[ 2857.026114] Call Trace:
[ 2857.026119]  [<ffffffff8104db2e>] warn_slowpath_common+0x85/0x9d
[ 2857.026124]  [<ffffffff8104db60>] warn_slowpath_null+0x1a/0x1c
[ 2857.026138]  [<ffffffffa029cc98>] btrfs_alloc_free_block+0x14e/0x357 [btrfs]
[ 2857.026156]  [<ffffffffa02c75bb>] ? map_private_extent_buffer+0xb1/0xd5 [btrfs]
[ 2857.026167]  [<ffffffffa028f99f>] __btrfs_cow_block+0x102/0x31e [btrfs]
[ 2857.026178]  [<ffffffffa028e500>] ? unlock_up+0xd9/0xe4 [btrfs]
[ 2857.026188]  [<ffffffffa028fcbf>] btrfs_cow_block+0x104/0x14e [btrfs]
[ 2857.026199]  [<ffffffffa0292aa0>] btrfs_search_slot+0x162/0x502 [btrfs]
[ 2857.026215]  [<ffffffffa02a0e16>] btrfs_lookup_file_extent+0x3c/0x3e [btrfs]
[ 2857.026225]  [<ffffffffa028f13c>] ? btrfs_alloc_path+0x1a/0x2b [btrfs]
[ 2857.026243]  [<ffffffffa02b684d>] btrfs_drop_extents+0x10e/0x731 [btrfs]
[ 2857.026250]  [<ffffffff8103d050>] ? need_resched+0x23/0x2d
[ 2857.026256]  [<ffffffff8147a88e>] ? _cond_resched+0xe/0x22
[ 2857.026262]  [<ffffffff8110f8e8>] ? slab_pre_alloc_hook.clone.33+0x2d/0x31
[ 2857.026268]  [<ffffffff81110422>] ? kmem_cache_alloc+0x29/0xf7
[ 2857.026287]  [<ffffffffa02adafc>] insert_reserved_file_extent.clone.34+0x70/0x1fc [btrfs]
[ 2857.026309]  [<ffffffffa02c4708>] ? lock_extent_bits+0x5e/0xa8 [btrfs]
[ 2857.026328]  [<ffffffffa02b0772>] btrfs_endio_direct_write+0x171/0x29a [btrfs]
[ 2857.026347]  [<ffffffffa02a3afa>] ? end_workqueue_fn+0xf6/0x10e [btrfs]
[ 2857.026354]  [<ffffffff81143d1c>] bio_endio+0x2d/0x2f
[ 2857.026370]  [<ffffffffa02a3b05>] end_workqueue_fn+0x101/0x10e [btrfs]
[ 2857.026390]  [<ffffffffa02cde4d>] worker_loop+0x193/0x4ca [btrfs]
[ 2857.026410]  [<ffffffffa02cdcba>] ? btrfs_queue_worker+0x214/0x214 [btrfs]
[ 2857.026415]  [<ffffffff81068f4e>] kthread+0x82/0x8a
[ 2857.026422]  [<ffffffff81483664>] kernel_thread_helper+0x4/0x10
[ 2857.026428]  [<ffffffff81068ecc>] ? kthread_worker_fn+0x14b/0x14b
[ 2857.026444]  [<ffffffff81483660>] ? gs_change+0x13/0x13
[ 2857.026448] ---[ end trace 11fa90e2fd0455aa ]---
[ 2857.026481] ------------[ cut here ]------------
[ 2857.026497] WARNING: at fs/btrfs/extent-tree.c:5648 btrfs_alloc_free_block+0x14e/0x357 [btrfs]()
[ 2857.026502] Hardware name: XPS 8300
[ 2857.026505] Modules linked in: tun btrfs zlib_deflate libcrc32c brd fuse cpufreq_ondemand acpi_cpufreq freq_table mperf ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables ipv6 uinput snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec snd_hwdep snd_seq snd_seq_device broadcom snd_pcm snd_timer snd tg3 iTCO_wdt serio_raw dcdbas iTCO_vendor_support microcode soundcore pcspkr snd_page_alloc i2c_i801 joydev usb_storage i915 drm_kms_helper drm i2c_algo_bit i2c_core video [last unloaded: scsi_wait_scan]
[ 2857.026584] Pid: 8833, comm: btrfs-endio-wri Tainted: G        W 3.0.0-rc1-work-2011-06-01-01+ #11
[ 2857.026586] Call Trace:
[ 2857.026589]  [<ffffffff8104db2e>] warn_slowpath_common+0x85/0x9d
[ 2857.026592]  [<ffffffff8104db60>] warn_slowpath_null+0x1a/0x1c
[ 2857.026599]  [<ffffffffa029cc98>] btrfs_alloc_free_block+0x14e/0x357 [btrfs]
[ 2857.026608]  [<ffffffffa02c75bb>] ? map_private_extent_buffer+0xb1/0xd5 [btrfs]
[ 2857.026614]  [<ffffffffa028f99f>] __btrfs_cow_block+0x102/0x31e [btrfs]
[ 2857.026620]  [<ffffffffa028e500>] ? unlock_up+0xd9/0xe4 [btrfs]
[ 2857.026626]  [<ffffffffa028fcbf>] btrfs_cow_block+0x104/0x14e [btrfs]
[ 2857.026632]  [<ffffffffa0292aa0>] btrfs_search_slot+0x162/0x502 [btrfs]
[ 2857.026640]  [<ffffffffa02a0e16>] btrfs_lookup_file_extent+0x3c/0x3e [btrfs]
[ 2857.026646]  [<ffffffffa028f13c>] ? btrfs_alloc_path+0x1a/0x2b [btrfs]
[ 2857.026655]  [<ffffffffa02b684d>] btrfs_drop_extents+0x10e/0x731 [btrfs]
[ 2857.026658]  [<ffffffff8103d050>] ? need_resched+0x23/0x2d
[ 2857.026661]  [<ffffffff8147a88e>] ? _cond_resched+0xe/0x22
[ 2857.026663]  [<ffffffff8110f8e8>] ? slab_pre_alloc_hook.clone.33+0x2d/0x31
[ 2857.026666]  [<ffffffff81110422>] ? kmem_cache_alloc+0x29/0xf7
[ 2857.026674]  [<ffffffffa02adafc>] insert_reserved_file_extent.clone.34+0x70/0x1fc [btrfs]
[ 2857.026684]  [<ffffffffa02c4708>] ? lock_extent_bits+0x5e/0xa8 [btrfs]
[ 2857.026693]  [<ffffffffa02b0772>] btrfs_endio_direct_write+0x171/0x29a [btrfs]
[ 2857.026701]  [<ffffffffa02a3afa>] ? end_workqueue_fn+0xf6/0x10e [btrfs]
[ 2857.026704]  [<ffffffff81143d1c>] bio_endio+0x2d/0x2f
[ 2857.026711]  [<ffffffffa02a3b05>] end_workqueue_fn+0x101/0x10e [btrfs]
[ 2857.026721]  [<ffffffffa02cde4d>] worker_loop+0x193/0x4ca [btrfs]
[ 2857.026730]  [<ffffffffa02cdcba>] ? btrfs_queue_worker+0x214/0x214 [btrfs]
[ 2857.026732]  [<ffffffff81068f4e>] kthread+0x82/0x8a
[ 2857.026735]  [<ffffffff81483664>] kernel_thread_helper+0x4/0x10
[ 2857.026738]  [<ffffffff81068ecc>] ? kthread_worker_fn+0x14b/0x14b
[ 2857.026741]  [<ffffffff81483660>] ? gs_change+0x13/0x13
[ 2857.026742] ---[ end trace 11fa90e2fd0455ab ]---
[ 2863.924897] ------------[ cut here ]------------
[ 2863.924924] WARNING: at fs/btrfs/extent-tree.c:3832 btrfs_free_block_groups+0x13a/0x228 [btrfs]()
[ 2863.924928] Hardware name: XPS 8300
[ 2863.924930] Modules linked in: tun btrfs zlib_deflate libcrc32c brd fuse cpufreq_ondemand acpi_cpufreq freq_table mperf ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables ipv6 uinput snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec snd_hwdep snd_seq snd_seq_device broadcom snd_pcm snd_timer snd tg3 iTCO_wdt serio_raw dcdbas iTCO_vendor_support microcode soundcore pcspkr snd_page_alloc i2c_i801 joydev usb_storage i915 drm_kms_helper drm i2c_algo_bit i2c_core video [last unloaded: scsi_wait_scan]
[ 2863.924977] Pid: 8875, comm: umount Tainted: G        W 3.0.0-rc1-work-2011-06-01-01+ #11
[ 2863.924980] Call Trace:
[ 2863.924988]  [<ffffffff8104db2e>] warn_slowpath_common+0x85/0x9d
[ 2863.924994]  [<ffffffff8104db60>] warn_slowpath_null+0x1a/0x1c
[ 2863.925009]  [<ffffffffa029d9fe>] btrfs_free_block_groups+0x13a/0x228 [btrfs]
[ 2863.925026]  [<ffffffffa02a68c2>] close_ctree+0x22c/0x346 [btrfs]
[ 2863.925031]  [<ffffffff8103d068>] ? should_resched+0xe/0x2e
[ 2863.925036]  [<ffffffff8147a88e>] ? _cond_resched+0xe/0x22
[ 2863.925040]  [<ffffffff8147b465>] ? down_write+0x29/0x49
[ 2863.925050]  [<ffffffffa028ca1e>] btrfs_put_super+0x1d/0x2c [btrfs]
[ 2863.925056]  [<ffffffff8111ecb8>] generic_shutdown_super+0x74/0xe9
[ 2863.925060]  [<ffffffff8111edad>] kill_anon_super+0x16/0x50
[ 2863.925065]  [<ffffffff8111efda>] deactivate_locked_super+0x26/0x4b
[ 2863.925069]  [<ffffffff8111f7c9>] deactivate_super+0x3a/0x3f
[ 2863.925073]  [<ffffffff81134a0d>] mntput_no_expire+0xd0/0xd5
[ 2863.925076]  [<ffffffff8113568c>] sys_umount+0x2dc/0x30a
[ 2863.925081]  [<ffffffff81125c68>] ? path_put+0x22/0x27
[ 2863.925085]  [<ffffffff81482542>] system_call_fastpath+0x16/0x1b
[ 2863.925089] ---[ end trace 11fa90e2fd0455ac ]---
[ 2863.925091] ------------[ cut here ]------------
[ 2863.925104] WARNING: at fs/btrfs/extent-tree.c:3833 btrfs_free_block_groups+0x155/0x228 [btrfs]()
[ 2863.925107] Hardware name: XPS 8300
[ 2863.925109] Modules linked in: tun btrfs zlib_deflate libcrc32c brd fuse cpufreq_ondemand acpi_cpufreq freq_table mperf ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables ipv6 uinput snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec snd_hwdep snd_seq snd_seq_device broadcom snd_pcm snd_timer snd tg3 iTCO_wdt serio_raw dcdbas iTCO_vendor_support microcode soundcore pcspkr snd_page_alloc i2c_i801 joydev usb_storage i915 drm_kms_helper drm i2c_algo_bit i2c_core video [last unloaded: scsi_wait_scan]
[ 2863.925147] Pid: 8875, comm: umount Tainted: G        W 3.0.0-rc1-work-2011-06-01-01+ #11
[ 2863.925150] Call Trace:
[ 2863.925154]  [<ffffffff8104db2e>] warn_slowpath_common+0x85/0x9d
[ 2863.925159]  [<ffffffff8104db60>] warn_slowpath_null+0x1a/0x1c
[ 2863.925172]  [<ffffffffa029da19>] btrfs_free_block_groups+0x155/0x228 [btrfs]
[ 2863.925188]  [<ffffffffa02a68c2>] close_ctree+0x22c/0x346 [btrfs]
[ 2863.925193]  [<ffffffff8103d068>] ? should_resched+0xe/0x2e
[ 2863.925196]  [<ffffffff8147a88e>] ? _cond_resched+0xe/0x22
[ 2863.925200]  [<ffffffff8147b465>] ? down_write+0x29/0x49
[ 2863.925209]  [<ffffffffa028ca1e>] btrfs_put_super+0x1d/0x2c [btrfs]
[ 2863.925214]  [<ffffffff8111ecb8>] generic_shutdown_super+0x74/0xe9
[ 2863.925218]  [<ffffffff8111edad>] kill_anon_super+0x16/0x50
[ 2863.925223]  [<ffffffff8111efda>] deactivate_locked_super+0x26/0x4b
[ 2863.925227]  [<ffffffff8111f7c9>] deactivate_super+0x3a/0x3f
[ 2863.925231]  [<ffffffff81134a0d>] mntput_no_expire+0xd0/0xd5
[ 2863.925234]  [<ffffffff8113568c>] sys_umount+0x2dc/0x30a
[ 2863.925238]  [<ffffffff81125c68>] ? path_put+0x22/0x27
[ 2863.925242]  [<ffffffff81482542>] system_call_fastpath+0x16/0x1b
[ 2863.925245] ---[ end trace 11fa90e2fd0455ad ]---
[ 2863.925248] ------------[ cut here ]------------
[ 2863.925261] WARNING: at fs/btrfs/extent-tree.c:6846 btrfs_free_block_groups+0x1e6/0x228 [btrfs]()
[ 2863.925263] Hardware name: XPS 8300
[ 2863.925265] Modules linked in: tun btrfs zlib_deflate libcrc32c brd fuse cpufreq_ondemand acpi_cpufreq freq_table mperf ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables ipv6 uinput snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec snd_hwdep snd_seq snd_seq_device broadcom snd_pcm snd_timer snd tg3 iTCO_wdt serio_raw dcdbas iTCO_vendor_support microcode soundcore pcspkr snd_page_alloc i2c_i801 joydev usb_storage i915 drm_kms_helper drm i2c_algo_bit i2c_core video [last unloaded: scsi_wait_scan]
[ 2863.925303] Pid: 8875, comm: umount Tainted: G        W 3.0.0-rc1-work-2011-06-01-01+ #11
[ 2863.925305] Call Trace:
[ 2863.925310]  [<ffffffff8104db2e>] warn_slowpath_common+0x85/0x9d
[ 2863.925323]  [<ffffffffa029dac8>] ? btrfs_free_block_groups+0x204/0x228 [btrfs]
[ 2863.925328]  [<ffffffff8104db60>] warn_slowpath_null+0x1a/0x1c
[ 2863.925341]  [<ffffffffa029daaa>] btrfs_free_block_groups+0x1e6/0x228 [btrfs]
[ 2863.925356]  [<ffffffffa02a68c2>] close_ctree+0x22c/0x346 [btrfs]
[ 2863.925360]  [<ffffffff8103d068>] ? should_resched+0xe/0x2e
[ 2863.925364]  [<ffffffff8147a88e>] ? _cond_resched+0xe/0x22
[ 2863.925368]  [<ffffffff8147b465>] ? down_write+0x29/0x49
[ 2863.925377]  [<ffffffffa028ca1e>] btrfs_put_super+0x1d/0x2c [btrfs]
[ 2863.925382]  [<ffffffff8111ecb8>] generic_shutdown_super+0x74/0xe9
[ 2863.925386]  [<ffffffff8111edad>] kill_anon_super+0x16/0x50
[ 2863.925391]  [<ffffffff8111efda>] deactivate_locked_super+0x26/0x4b
[ 2863.925395]  [<ffffffff8111f7c9>] deactivate_super+0x3a/0x3f
[ 2863.925398]  [<ffffffff81134a0d>] mntput_no_expire+0xd0/0xd5
[ 2863.925402]  [<ffffffff8113568c>] sys_umount+0x2dc/0x30a
[ 2863.925406]  [<ffffffff81125c68>] ? path_put+0x22/0x27
[ 2863.925410]  [<ffffffff81482542>] system_call_fastpath+0x16/0x1b
[ 2863.925413] ---[ end trace 11fa90e2fd0455ae ]---
[ 2863.925416] space_info has 13627392 free, is full
[ 2863.925419] space_info total=41943040, used=19832832, pinned=0, reserved=28672, may_use=0, readonly=8454144

Some btrfs complaints
---------------------

[ 3704.817050] btrfs no csum found for inode 17005 start 1302528
[ 3704.817058] btrfs no csum found for inode 17005 start 1306624
[ 3704.817064] btrfs no csum found for inode 17005 start 1310720
[ 3704.817089] btrfs no csum found for inode 17005 start 1314816
[ 3704.817094] btrfs no csum found for inode 17005 start 1318912
[ 3704.817100] btrfs no csum found for inode 17005 start 1323008
[ 3704.817105] btrfs no csum found for inode 17005 start 1327104
[ 3704.817111] btrfs no csum found for inode 17005 start 1331200
[ 3704.817117] btrfs no csum found for inode 17005 start 1335296
[ 3704.817122] btrfs no csum found for inode 17005 start 1339392
[ 3704.817128] btrfs no csum found for inode 17005 start 1343488
[ 3704.817133] btrfs no csum found for inode 17005 start 1347584
[ 3704.817139] btrfs no csum found for inode 17005 start 1351680
[ 3704.817309] btrfs csum failed ino 17005 off 1302528 csum 451097791 private 0
[ 3704.817350] btrfs csum failed ino 17005 off 1306624 csum 451097791 private 0
[ 3704.817377] btrfs csum failed ino 17005 off 1310720 csum 451097791 private 0
[ 3704.817420] btrfs csum failed ino 17005 off 1314816 csum 978321154 private 0
[ 3704.817446] btrfs csum failed ino 17005 off 1318912 csum 2566472073 private 0
[ 3704.817472] btrfs csum failed ino 17005 off 1323008 csum 2566472073 private 0
[ 3704.817497] btrfs csum failed ino 17005 off 1327104 csum 2566472073 private 0
[ 3704.817523] btrfs csum failed ino 17005 off 1331200 csum 2566472073 private 0
[ 3704.817549] btrfs csum failed ino 17005 off 1335296 csum 2566472073 private 0
[ 3704.817575] btrfs csum failed ino 17005 off 1339392 csum 2566472073 private 0
[ 3704.817601] btrfs csum failed ino 17005 off 1343488 csum 2566472073 private 0
[ 3704.817627] btrfs csum failed ino 17005 off 1347584 csum 2566472073 private 0
[ 3704.817654] btrfs csum failed ino 17005 off 1351680 csum 2779917954 private 0

Hang
----

[152684.675833] btrfs-transacti D ffff880184e18bd0     0 22322      2 0x00000080
[152684.675835]  ffff88017c26dd60 0000000000000046 0000000000000000 ffff880100000001
[152684.675838]  0000000000012540 0000000000012540 0000000000012540 ffff8801a2524560
[152684.675840]  0000000000012540 ffff88017c26dfd8 0000000000012540 0000000000012540
[152684.675842] Call Trace:
[152684.675844]  [<ffffffff810696b2>] ? prepare_to_wait+0x6c/0x79
[152684.675856]  [<ffffffffa02a8190>] wait_for_commit.clone.14+0x90/0xd5 [btrfs]
[152684.675858]  [<ffffffff8106941f>] ? wake_up_bit+0x2a/0x2a
[152684.675866]  [<ffffffffa02a9007>] btrfs_commit_transaction+0x102/0x694 [btrfs]
[152684.675874]  [<ffffffffa02a8907>] ? join_transaction.clone.20+0x17b/0x186 [btrfs]
[152684.675876]  [<ffffffff8106941f>] ? wake_up_bit+0x2a/0x2a
[152684.675882]  [<ffffffffa02a3764>] transaction_kthread+0x17a/0x22f [btrfs]
[152684.675889]  [<ffffffffa02a35ea>] ? btrfs_congested_fn+0x86/0x86 [btrfs]
[152684.675891]  [<ffffffff81068f4e>] kthread+0x82/0x8a
[152684.675893]  [<ffffffff81483664>] kernel_thread_helper+0x4/0x10
[152684.675895]  [<ffffffff81068ecc>] ? kthread_worker_fn+0x14b/0x14b
[152684.675897]  [<ffffffff81483660>] ? gs_change+0x13/0x13
[152684.675898] flush-btrfs-770 D 00000001091bba6c     0 22331      2 0x00000080
[152684.675900]  ffff88017c19bb10 0000000000000046 ffff88017c19ba70 ffff880100000000
[152684.675902]  0000000000012540 0000000000012540 0000000000012540 ffff8801a2525c80
[152684.675905]  0000000000012540 ffff88017c19bfd8 0000000000012540 0000000000012540
[152684.675907] Call Trace:
[152684.675909]  [<ffffffff8147ab8c>] schedule_timeout+0x36/0xe3
[152684.675912]  [<ffffffff8107c30e>] ? arch_local_irq_save+0x18/0x1e
[152684.675914]  [<ffffffff8147be0f>] ? _raw_spin_unlock_irqrestore+0x17/0x19
[152684.675916]  [<ffffffff810696b2>] ? prepare_to_wait+0x6c/0x79
[152684.675923]  [<ffffffffa02a91c8>] btrfs_commit_transaction+0x2c3/0x694 [btrfs]
[152684.675924]  [<ffffffff8106941f>] ? wake_up_bit+0x2a/0x2a
[152684.675933]  [<ffffffffa02b2a07>] btrfs_write_inode+0xa0/0xa9 [btrfs]
[152684.675935]  [<ffffffff8113b12f>] writeback_single_inode+0x125/0x1bf
[152684.675937]  [<ffffffff8113b40f>] writeback_sb_inodes+0xce/0x160
[152684.675939]  [<ffffffff8113c036>] wb_writeback+0x258/0x3aa
[152684.675942]  [<ffffffff8113c211>] wb_do_writeback+0x89/0x1a1
[152684.675944]  [<ffffffff8105ad6e>] ? run_timer_softirq+0x29a/0x29a
[152684.675946]  [<ffffffff8113c3b5>] bdi_writeback_thread+0x8c/0x20f
[152684.675948]  [<ffffffff8113c329>] ? wb_do_writeback+0x1a1/0x1a1
[152684.675950]  [<ffffffff81068f4e>] kthread+0x82/0x8a
[152684.675952]  [<ffffffff81483664>] kernel_thread_helper+0x4/0x10
[152684.675954]  [<ffffffff81068ecc>] ? kthread_worker_fn+0x14b/0x14b
[152684.675956]  [<ffffffff81483660>] ? gs_change+0x13/0x13
[152684.675957] fsstress        D 0000000100363ef6     0 22334      1 0x00000084
[152684.675959]  ffff880169f8bb98 0000000000000082 0000000000000000 0000000000000000
[152684.675961]  0000000000012540 0000000000012540 0000000000012540 ffff880181f21720
[152684.675963]  0000000000012540 ffff880169f8bfd8 0000000000012540 0000000000012540
[152684.675966] Call Trace:
[152684.675967]  [<ffffffff810696b2>] ? prepare_to_wait+0x6c/0x79
[152684.675974]  [<ffffffffa02a8758>] wait_current_trans.clone.19+0xa0/0xd4 [btrfs]
[152684.675976]  [<ffffffff8106941f>] ? wake_up_bit+0x2a/0x2a
[152684.675977]  [<ffffffff8147afde>] ? mutex_lock+0x29/0x4a
[152684.675984]  [<ffffffffa02a988d>] start_transaction+0x98/0x24f [btrfs]
[152684.675991]  [<ffffffffa02a9d67>] btrfs_start_transaction+0x13/0x15 [btrfs]
[152684.675999]  [<ffffffffa02b3d72>] btrfs_create+0x3a/0x1de [btrfs]
[152684.676002]  [<ffffffff811276d3>] vfs_create+0x70/0x92
[152684.676004]  [<ffffffff8112791d>] do_last+0x228/0x599
[152684.676006]  [<ffffffff81128ffd>] path_openat+0xc8/0x34d
[152684.676007]  [<ffffffff81126dfa>] ? putname+0x34/0x36
[152684.676009]  [<ffffffff811292bf>] do_filp_open+0x3d/0x89
[152684.676012]  [<ffffffff81132e6a>] ? alloc_fd+0x74/0x11f
[152684.676014]  [<ffffffff8111c847>] do_sys_open+0x74/0x106
[152684.676015]  [<ffffffff8111c8f9>] sys_open+0x20/0x22
[152684.676017]  [<ffffffff8111c923>] sys_creat+0x15/0x17
[152684.676019]  [<ffffffff81482542>] system_call_fastpath+0x16/0x1b
[152684.676020] fsstress        D 0000000100363ef5     0 22335      1 0x00000084
[152684.676022]  ffff8801665018e8 0000000000000082 ffffffff81144cd4 00000000000000c0
[152684.676024]  0000000000012540 0000000000012540 0000000000012540 ffff880181f22e40
[152684.676027]  0000000000012540 ffff880166501fd8 0000000000012540 0000000000012540
[152684.676029] Call Trace:
[152684.676031]  [<ffffffff81144cd4>] ? bvec_alloc_bs+0xb0/0xcf
[152684.676033]  [<ffffffff8147ab8c>] schedule_timeout+0x36/0xe3
[152684.676041]  [<ffffffffa02c9d78>] ? __btrfs_map_block+0x5f1/0x609 [btrfs]
[152684.676043]  [<ffffffff8107c30e>] ? arch_local_irq_save+0x18/0x1e
[152684.676045]  [<ffffffff8103d050>] ? need_resched+0x23/0x2d
[152684.676047]  [<ffffffff8147a94f>] wait_for_common+0xad/0x102
[152684.676049]  [<ffffffff8104625f>] ? try_to_wake_up+0x1aa/0x1aa
[152684.676051]  [<ffffffff81053995>] ? local_bh_enable_ip+0xe/0x10
[152684.676053]  [<ffffffff8147aa5c>] wait_for_completion+0x1d/0x1f
[152684.676055]  [<ffffffff8113b892>] writeback_inodes_sb_nr+0x76/0x7d
[152684.676057]  [<ffffffff8113b945>] writeback_inodes_sb_nr_if_idle+0x41/0x57
[152684.676062]  [<ffffffffa0296eca>] shrink_delalloc.clone.46+0xb2/0x155 [btrfs]
[152684.676068]  [<ffffffffa0297066>] reserve_metadata_bytes.clone.47+0xf9/0x1b3 [btrfs]
[152684.676074]  [<ffffffffa0299c01>] btrfs_block_rsv_add+0x2c/0x4f [btrfs]
[152684.676080]  [<ffffffffa0299e2a>] btrfs_trans_reserve_metadata+0x4f/0x74 [btrfs]
[152684.676087]  [<ffffffffa02a9985>] start_transaction+0x190/0x24f [btrfs]
[152684.676094]  [<ffffffffa02a9d67>] btrfs_start_transaction+0x13/0x15 [btrfs]
[152684.676102]  [<ffffffffa02b3d72>] btrfs_create+0x3a/0x1de [btrfs]
[152684.676104]  [<ffffffff811276d3>] vfs_create+0x70/0x92
[152684.676106]  [<ffffffff8112791d>] do_last+0x228/0x599
[152684.676107]  [<ffffffff81128ffd>] path_openat+0xc8/0x34d
[152684.676109]  [<ffffffff8147be0f>] ? _raw_spin_unlock_irqrestore+0x17/0x19
[152684.676111]  [<ffffffff8147bda6>] ? _raw_spin_lock+0xe/0x10
[152684.676113]  [<ffffffff811292bf>] do_filp_open+0x3d/0x89
[152684.676115]  [<ffffffff81132e6a>] ? alloc_fd+0x74/0x11f
[152684.676117]  [<ffffffff8111c847>] do_sys_open+0x74/0x106
[152684.676119]  [<ffffffff8111c8f9>] sys_open+0x20/0x22
[152684.676120]  [<ffffffff8111c923>] sys_creat+0x15/0x17
[152684.676122]  [<ffffffff81482542>] system_call_fastpath+0x16/0x1b
[152684.676123] fsstress        D 0000000100363ef5     0 22336      1 0x00000084
[152684.676125]  ffff88017ba37d48 0000000000000086 ffff88017ba37cb8 ffffffff812262b8
[152684.676127]  0000000000012540 0000000000012540 0000000000012540 ffff880181b01720
[152684.676130]  0000000000012540 ffff88017ba37fd8 0000000000012540 0000000000012540
[152684.676132] Call Trace:
[152684.676134]  [<ffffffff812262b8>] ? cpumask_next_and+0x2c/0x39
[152684.676136]  [<ffffffff8147ab8c>] schedule_timeout+0x36/0xe3
[152684.676138]  [<ffffffff81026cb8>] ? flat_send_IPI_mask+0x11/0x13
[152684.676140]  [<ffffffff8103d050>] ? need_resched+0x23/0x2d
[152684.676142]  [<ffffffff8147a94f>] wait_for_common+0xad/0x102
[152684.676143]  [<ffffffff8104625f>] ? try_to_wake_up+0x1aa/0x1aa
[152684.676145]  [<ffffffff81053995>] ? local_bh_enable_ip+0xe/0x10
[152684.676147]  [<ffffffff8113f1e8>] ? __sync_filesystem+0x7a/0x7a
[152684.676148]  [<ffffffff8147aa5c>] wait_for_completion+0x1d/0x1f
[152684.676150]  [<ffffffff8113b9ec>] sync_inodes_sb+0x91/0x17d
[152684.676152]  [<ffffffff8113f1e8>] ? __sync_filesystem+0x7a/0x7a
[152684.676154]  [<ffffffff8113f1b5>] __sync_filesystem+0x47/0x7a
[152684.676155]  [<ffffffff8113f1fe>] sync_one_sb+0x16/0x18
[152684.676157]  [<ffffffff8111f907>] iterate_supers+0x6d/0xbe
[152684.676159]  [<ffffffff8113f133>] sync_filesystems+0x20/0x22
[152684.676160]  [<ffffffff8113f271>] sys_sync+0x21/0x33
[152684.676162]  [<ffffffff81482542>] system_call_fastpath+0x16/0x1b
[152684.676164] updatedb        D 0000000102716c7c     0 25199  25193 0x00000080
[152684.676166]  ffff88017fb01e28 0000000000000086 ffff88017fb01f28 ffff880100000000
[152684.676168]  0000000000012540 0000000000012540 0000000000012540 ffff88019ee0ae40
[152684.676170]  0000000000012540 ffff88017fb01fd8 0000000000012540 0000000000012540
[152684.676172] Call Trace:
[152684.676174]  [<ffffffff8147b11a>] __mutex_lock_common.clone.5+0x11b/0x17c
[152684.676177]  [<ffffffff8112b56c>] ? filldir64+0xd5/0xd5
[152684.676178]  [<ffffffff8147b1a3>] __mutex_lock_killable_slowpath+0x13/0x15
[152684.676181]  [<ffffffff8106bea1>] __mutex_fastpath_lock_retval+0x18/0x1a
[152684.676182]  [<ffffffff8147af53>] mutex_lock_killable+0x38/0x4d
[152684.676184]  [<ffffffff8112b74c>] vfs_readdir+0x56/0xac
[152684.676186]  [<ffffffff8112b88b>] sys_getdents+0x81/0xd1
[152684.676188]  [<ffffffff81482542>] system_call_fastpath+0x16/0x1b
[152684.676191] sync            D 00000001091bba63     0 26977   1943 0x00000080
[152684.676193]  ffff880183239d48 0000000000000086 0007ffffffffffff ffff880100000000
[152684.676196]  0000000000012540 0000000000012540 0000000000012540 ffff880181b04560
[152684.676198]  0000000000012540 ffff880183239fd8 0000000000012540 0000000000012540
[152684.676200] Call Trace:
[152684.676202]  [<ffffffff8147ab8c>] schedule_timeout+0x36/0xe3
[152684.676203]  [<ffffffff81026cb8>] ? flat_send_IPI_mask+0x11/0x13
[152684.676205]  [<ffffffff8103d050>] ? need_resched+0x23/0x2d
[152684.676207]  [<ffffffff8147a94f>] wait_for_common+0xad/0x102
[152684.676209]  [<ffffffff8104625f>] ? try_to_wake_up+0x1aa/0x1aa
[152684.676210]  [<ffffffff81053995>] ? local_bh_enable_ip+0xe/0x10
[152684.676212]  [<ffffffff8113f1e8>] ? __sync_filesystem+0x7a/0x7a
[152684.676214]  [<ffffffff8147aa5c>] wait_for_completion+0x1d/0x1f
[152684.676216]  [<ffffffff8113b892>] writeback_inodes_sb_nr+0x76/0x7d
[152684.676218]  [<ffffffff8113b8bb>] writeback_inodes_sb+0x22/0x24
[152684.676219]  [<ffffffff8113f1bf>] __sync_filesystem+0x51/0x7a
[152684.676221]  [<ffffffff8113f1fe>] sync_one_sb+0x16/0x18
[152684.676223]  [<ffffffff8111f907>] iterate_supers+0x6d/0xbe
[152684.676224]  [<ffffffff8113f133>] sync_filesystems+0x20/0x22
[152684.676226]  [<ffffffff8113f267>] sys_sync+0x17/0x33
[152684.676227]  [<ffffffff81482542>] system_call_fastpath+0x16/0x1b

And on 59c5f46fbe01a00eedf54a23789634438bb80603 Linux 3.0-rc2 btrfs quickly fails to mount due to no space e.g.

Script
------

#!/bin/sh

sudo modprobe brd rd_size=262144

sudo umount /mnt/test/ 2> /dev/null

echo 'mkfs.btrfs /dev/ram0'

sudo mkfs.btrfs /dev/ram0

sudo mkdir -p /mnt/test

echo 'mount -t btrfs /dev/ram0 /mnt/test'

sudo mount -t btrfs /dev/ram0 /mnt/test

sudo mkdir -p /mnt/test/test

sudo chown $USER /mnt/test/test
sudo chgrp $USER /mnt/test/test

sudo umount /mnt/test

full=0
i=0
while true; do

	sudo mount -t btrfs /dev/ram0 /mnt/test

	if df | grep ram0 | grep 100% > /dev/null; then
		full=`expr $full \+ 1`
		if test $full -gt 6;then
			rm -rf /mnt/test/test/*
			full=0
		fi
	else
		full=0
	fi

	fsstress -c -r -d /mnt/test/test -p 3 -n 1000 -l 10

	sudo umount /mnt/test

	i=`expr $i \+ 1`
	echo $i

done

Script Output
-------------

mkfs.btrfs /dev/ram0

WARNING! - Btrfs Btrfs v0.19 IS EXPERIMENTAL WARNING! - see http://btrfs.wiki.kernel.org before using

fs created label (null) on /dev/ram0

	nodesize 4096 leafsize 4096 sectorsize 4096 size 256.00MB

Btrfs Btrfs v0.19
mount -t btrfs /dev/ram0 /mnt/test
1
2
3
4
mount: No space left on device
^C

Kernel messages
---------------

[   95.084429] brd: module loaded
[   95.368708] Btrfs loaded
[   95.369455] device fsid 9644bae59f78285c-8db3a698a8a82293 devid 1 transid 7 /dev/ram0
[   95.370582] SELinux: initialized (dev ram0, type btrfs), uses xattr
[   95.487905] device fsid 9644bae59f78285c-8db3a698a8a82293 devid 1 transid 10 /dev/ram0
[   95.488889] SELinux: initialized (dev ram0, type btrfs), uses xattr
[  107.336869] device fsid 9644bae59f78285c-8db3a698a8a82293 devid 1 transid 2664 /dev/ram0
[  107.338873] SELinux: initialized (dev ram0, type btrfs), uses xattr
[  115.861909] device fsid 9644bae59f78285c-8db3a698a8a82293 devid 1 transid 6816 /dev/ram0
[  115.864089] SELinux: initialized (dev ram0, type btrfs), uses xattr
[  122.586606] device fsid 9644bae59f78285c-8db3a698a8a82293 devid 1 transid 10872 /dev/ram0
[  122.587779] SELinux: initialized (dev ram0, type btrfs), uses xattr
[  128.824401] BTRFS: inode 19622 still on the orphan list
[  128.844945] ------------[ cut here ]------------
[  128.844969] WARNING: at fs/btrfs/extent-tree.c:6878 btrfs_free_block_groups+0x1e6/0x228 [btrfs]()
[  128.844973] Hardware name: XPS 8300
[  128.844974] Modules linked in: btrfs zlib_deflate libcrc32c brd tun fuse cpufreq_ondemand acpi_cpufreq freq_table mperf ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables ipv6 uinput snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec snd_hwdep snd_seq snd_seq_device snd_pcm broadcom snd_timer snd tg3 pcspkr joydev iTCO_wdt iTCO_vendor_support soundcore snd_page_alloc i2c_i801 serio_raw dcdbas microcode usb_storage i915 drm_kms_helper drm i2c_algo_bit i2c_core video [last unloaded: scsi_wait_scan]
[  128.845024] Pid: 2503, comm: umount Not tainted 3.0.0-rc2-2011-06-06-02+ #13
[  128.845026] Call Trace:
[  128.845035]  [<ffffffff8104db2e>] warn_slowpath_common+0x85/0x9d
[  128.845050]  [<ffffffffa02a6b70>] ? btrfs_free_block_groups+0x204/0x228 [btrfs]
[  128.845056]  [<ffffffff8104db60>] warn_slowpath_null+0x1a/0x1c
[  128.845069]  [<ffffffffa02a6b52>] btrfs_free_block_groups+0x1e6/0x228 [btrfs]
[  128.845087]  [<ffffffffa02afa0b>] close_ctree+0x22c/0x346 [btrfs]
[  128.845092]  [<ffffffff8103d068>] ? should_resched+0xe/0x2e
[  128.845097]  [<ffffffff8147abfe>] ? _cond_resched+0xe/0x22
[  128.845100]  [<ffffffff8147b7d5>] ? down_write+0x29/0x49
[  128.845110]  [<ffffffffa0295a1e>] btrfs_put_super+0x1d/0x2c [btrfs]
[  128.845116]  [<ffffffff8111ecb4>] generic_shutdown_super+0x74/0xe9
[  128.845120]  [<ffffffff8111eda9>] kill_anon_super+0x16/0x50
[  128.845125]  [<ffffffff8111efd6>] deactivate_locked_super+0x26/0x4b
[  128.845129]  [<ffffffff8111f7c5>] deactivate_super+0x3a/0x3f
[  128.845133]  [<ffffffff81134a09>] mntput_no_expire+0xd0/0xd5
[  128.845136]  [<ffffffff81135688>] sys_umount+0x2dc/0x30a
[  128.845141]  [<ffffffff81125c64>] ? path_put+0x22/0x27
[  128.845145]  [<ffffffff814828c2>] system_call_fastpath+0x16/0x1b
[  128.845149] ---[ end trace e535ebf83dd43354 ]---
[  128.845152] space_info has 8814592 free, is full
[  128.845156] space_info total=41943040, used=24576000, pinned=0, reserved=98304, may_use=0, readonly=8454144
[  128.897312] device fsid 9644bae59f78285c-8db3a698a8a82293 devid 1 transid 14722 /dev/ram0
[  128.910740] BTRFS: inode 19622 still on the orphan list
[  128.910747] btrfs: could not do orphan cleanup -28
[  128.948912] btrfs: open_ctree failed