From: Liu Bo Date: Fri, 14 Aug 2015 10:33:07 +0000 (+0800) Subject: Btrfs: move kobj stuff out of dev_replace lock range X-Git-Tag: v4.4-rc1~82^2~39^2 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=73416dab235e5ff030e3b3c61da0cd6ced324fc9;p=linux.git Btrfs: move kobj stuff out of dev_replace lock range To avoid deadlock described in commit 084b6e7c7607 ("btrfs: Fix a lockdep warning when running xfstest."), we should move kobj stuff out of dev_replace lock range. "It is because the btrfs_kobj_{add/rm}_device() will call memory allocation with GFP_KERNEL, which may flush fs page cache to free space, waiting for it self to do the commit, causing the deadlock. To solve the problem, move btrfs_kobj_{add/rm}_device() out of the dev_replace lock range, also involing split the btrfs_rm_dev_replace_srcdev() function into remove and free parts. Now only btrfs_rm_dev_replace_remove_srcdev() is called in dev_replace lock range, and kobj_{add/rm} and btrfs_rm_dev_replace_free_srcdev() are called out of the lock range." Signed-off-by: Liu Bo Signed-off-by: Anand Jain [added lockup description] Signed-off-by: David Sterba --- diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c index 02031fc07f7f..0978e52ffa42 100644 --- a/fs/btrfs/dev-replace.c +++ b/fs/btrfs/dev-replace.c @@ -375,10 +375,6 @@ int btrfs_dev_replace_start(struct btrfs_root *root, WARN_ON(!tgt_device); dev_replace->tgtdev = tgt_device; - ret = btrfs_sysfs_add_device_link(tgt_device->fs_devices, tgt_device); - if (ret) - btrfs_err(root->fs_info, "kobj add dev failed %d\n", ret); - printk_in_rcu(KERN_INFO "BTRFS: dev_replace from %s (devid %llu) to %s started\n", src_device->missing ? "" : @@ -401,6 +397,10 @@ int btrfs_dev_replace_start(struct btrfs_root *root, args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR; btrfs_dev_replace_unlock(dev_replace); + ret = btrfs_sysfs_add_device_link(tgt_device->fs_devices, tgt_device); + if (ret) + btrfs_err(root->fs_info, "kobj add dev failed %d\n", ret); + btrfs_wait_ordered_roots(root->fs_info, -1); /* force writing the updated state information to disk */