Tejun Heo a1a0e23e49 writeback: flush inode cgroup wb switches instead of pinning super_block ... If cgroup writeback is in use, inodes can be scheduled for asynchronous wb switching. Before 5ff8eaac16 ("writeback: keep superblock pinned during cgroup writeback association switches"), this could race with umount leading to super_block being destroyed while inodes are pinned for wb switching. 5ff8eaac16 fixed it by bumping s_active while wb switches are in flight; however, this allowed in-flight wb switches to make umounts asynchronous when the userland expected synchronosity - e.g. fsck immediately following umount may fail because the device is still busy. This patch removes the problematic super_block pinning and instead makes generic_shutdown_super() flush in-flight wb switches. wb switches are now executed on a dedicated isw_wq so that they can be flushed and isw_nr_in_flight keeps track of the number of in-flight wb switches so that flushing can be avoided in most cases. v2: Move cgroup_writeback_umount() further below and add MS_ACTIVE check in inode_switch_wbs() as Jan an Al suggested. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Tahsin Erdogan <tahsin@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Al Viro <viro@ZenIV.linux.org.uk> Link: http://lkml.kernel.org/g/CAAeU0aNCq7LGODvVGRU-oU_o-6enii5ey0p1c26D1ZzYwkDc5A@mail.gmail.com Fixes: 5ff8eaac16 ("writeback: keep superblock pinned during cgroup writeback association switches") Cc: stable@vger.kernel.org #v4.5 Reviewed-by: Jan Kara <jack@suse.cz> Tested-by: Tahsin Erdogan <tahsin@google.com> Signed-off-by: Jens Axboe <axboe@fb.com>		2016-03-03 14:42:50 -07:00
..
acpi	ACPI / CPPC: remove redundant mbox_send_message() declaration	2016-02-03 01:09:52 +01:00
asm-generic	powerpc fixes for 4.5 #2	2016-02-20 09:22:11 -08:00
clocksource
crypto	Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6	2016-01-22 11:58:43 -08:00
drm	drm/atomic: Allow for holes in connector state, v2.	2016-02-19 13:24:03 +10:00
dt-bindings	clk: tegra: Add the APB2APE audio clock on Tegra210	2016-02-02 15:49:29 +01:00
keys
kvm
linux	writeback: flush inode cgroup wb switches instead of pinning super_block	2016-03-03 14:42:50 -07:00
math-emu
media	[media] vb2: fix nasty vb2_thread regression	2016-02-04 09:13:46 -02:00
memory
misc
net	tcp/dccp: fix another race at listener dismantle	2016-02-18 11:35:51 -05:00
pcmcia
ras
rdma	IB/mlx4: Enable send of RoCE QP1 packets with IP/UDP headers	2016-01-19 15:35:01 -05:00
rxrpc
scsi	Initial roundup of 4.5 merge window patches	2016-01-23 18:45:06 -08:00
soc	ARM: SoC driver updates for v4.5	2016-01-20 18:42:30 -08:00
sound	ALSA: hda - Loop interrupt handling until really cleared	2016-02-26 08:50:31 +01:00
target	target/transport: add flag to indicate CPU Affinity is observed	2016-02-10 23:08:55 -08:00
trace	This includes three minor fixes, mostly due to cut-and-paste issues.	2016-01-28 17:00:50 -08:00
uapi	nfit: update address range scrub commands to the acpi 6.1 format	2016-02-23 17:17:20 -08:00
video
xen	Merge branch 'for-4.5/drivers' of git://git.kernel.dk/linux-block	2016-01-21 18:19:38 -08:00
Kbuild