From: Lu Fengqi Date: Thu, 29 Nov 2018 09:31:32 +0000 (+0800) Subject: btrfs: skip file_extent generation check for free_space_inode in run_delalloc_nocow X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=27a7ff554e8d349627a90bda275c527b7348adae;p=openwrt%2Fstaging%2Fblogic.git btrfs: skip file_extent generation check for free_space_inode in run_delalloc_nocow The test case btrfs/001 with inode_cache mount option will encounter the following warning: WARNING: CPU: 1 PID: 23700 at fs/btrfs/inode.c:956 cow_file_range.isra.19+0x32b/0x430 [btrfs] CPU: 1 PID: 23700 Comm: btrfs Kdump: loaded Tainted: G W O 4.20.0-rc4-custom+ #30 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:cow_file_range.isra.19+0x32b/0x430 [btrfs] Call Trace: ? free_extent_buffer+0x46/0x90 [btrfs] run_delalloc_nocow+0x455/0x900 [btrfs] btrfs_run_delalloc_range+0x1a7/0x360 [btrfs] writepage_delalloc+0xf9/0x150 [btrfs] __extent_writepage+0x125/0x3e0 [btrfs] extent_write_cache_pages+0x1b6/0x3e0 [btrfs] ? __wake_up_common_lock+0x63/0xc0 extent_writepages+0x50/0x80 [btrfs] do_writepages+0x41/0xd0 ? __filemap_fdatawrite_range+0x9e/0xf0 __filemap_fdatawrite_range+0xbe/0xf0 btrfs_fdatawrite_range+0x1b/0x50 [btrfs] __btrfs_write_out_cache+0x42c/0x480 [btrfs] btrfs_write_out_ino_cache+0x84/0xd0 [btrfs] btrfs_save_ino_cache+0x551/0x660 [btrfs] commit_fs_roots+0xc5/0x190 [btrfs] btrfs_commit_transaction+0x2bf/0x8d0 [btrfs] btrfs_mksubvol+0x48d/0x4d0 [btrfs] btrfs_ioctl_snap_create_transid+0x170/0x180 [btrfs] btrfs_ioctl_snap_create_v2+0x124/0x180 [btrfs] btrfs_ioctl+0x123f/0x3030 [btrfs] The file extent generation of the free space inode is equal to the last snapshot of the file root, so the inode will be passed to cow_file_rage. But the inode was created and its extents were preallocated in btrfs_save_ino_cache, there are no cow copies on disk. The preallocated extent is not yet in the extent tree, and btrfs_cross_ref_exist will ignore the -ENOENT returned by check_committed_ref, so we can directly write the inode to the disk. Fixes: 78d4295b1eee ("btrfs: lift some btrfs_cross_ref_exist checks in nocow path") CC: stable@vger.kernel.org # 4.18+ Reviewed-by: Filipe Manana Signed-off-by: Lu Fengqi Signed-off-by: David Sterba --- diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index b4129d9072ec..e7b97c699acf 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -1369,7 +1369,8 @@ next_slot: * Do the same check as in btrfs_cross_ref_exist but * without the unnecessary search. */ - if (btrfs_file_extent_generation(leaf, fi) <= + if (!nolock && + btrfs_file_extent_generation(leaf, fi) <= btrfs_root_last_snapshot(&root->root_item)) goto out_check; if (extent_type == BTRFS_FILE_EXTENT_REG && !force)