| Message ID | 1363695767-8141-1-git-send-email-luis.henriques@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 2208f0f..446896d 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -609,6 +609,12 @@ int btrfs_close_devices(struct btrfs_fs_devices *fs_devices) __btrfs_close_devices(fs_devices); free_fs_devices(fs_devices); } + /* + * Wait for rcu kworkers under __btrfs_close_devices + * to finish all blkdev_puts so device is really + * free when umount is done. + */ + rcu_barrier(); return ret; }
This is a note to let you know that I have just added a patch titled btrfs: use rcu_barrier() to wait for bdev puts at unmount to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.5.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From fb5e30677089e58d058977d56fc63afcd3a1d32b Mon Sep 17 00:00:00 2001 From: Eric Sandeen <sandeen@redhat.com> Date: Sat, 9 Mar 2013 15:18:39 +0000 Subject: [PATCH] btrfs: use rcu_barrier() to wait for bdev puts at unmount commit bc178622d40d87e75abc131007342429c9b03351 upstream. Doing this would reliably fail with -EBUSY for me: # mount /dev/sdb2 /mnt/scratch; umount /mnt/scratch; mkfs.btrfs -f /dev/sdb2 ... unable to open /dev/sdb2: Device or resource busy because mkfs.btrfs tries to open the device O_EXCL, and somebody still has it. Using systemtap to track bdev gets & puts shows a kworker thread doing a blkdev put after mkfs attempts a get; this is left over from the unmount path: btrfs_close_devices __btrfs_close_devices call_rcu(&device->rcu, free_device); free_device INIT_WORK(&device->rcu_work, __free_device); schedule_work(&device->rcu_work); so unmount might complete before __free_device fires & does its blkdev_put. Adding an rcu_barrier() to btrfs_close_devices() causes unmount to wait until all blkdev_put()s are done, and the device is truly free once unmount completes. Signed-off-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: Josef Bacik <jbacik@fusionio.com> Signed-off-by: Chris Mason <chris.mason@fusionio.com> Luis Henriques <luis.henriques@canonical.com> --- fs/btrfs/volumes.c | 6 ++++++ 1 file changed, 6 insertions(+) -- 1.8.1.2