From 8b8c753d20e5e82aea179725eb254908d1b9d477 Mon Sep 17 00:00:00 2001 From: Robbie Ko Date: Tue, 30 Oct 2018 18:04:04 +0800 Subject: Btrfs: fix cur_offset in the error case for nocow commit 506481b20e818db40b6198815904ecd2d6daee64 upstream. When the cow_file_range fails, the related resources are unlocked according to the range [start..end), so the unlock cannot be repeated in run_delalloc_nocow. In some cases (e.g. cur_offset <= end && cow_start != -1), cur_offset is not updated correctly, so move the cur_offset update before cow_file_range. kernel BUG at mm/page-writeback.c:2663! Internal error: Oops - BUG: 0 [#1] SMP CPU: 3 PID: 31525 Comm: kworker/u8:7 Tainted: P O Hardware name: Realtek_RTD1296 (DT) Workqueue: writeback wb_workfn (flush-btrfs-1) task: ffffffc076db3380 ti: ffffffc02e9ac000 task.ti: ffffffc02e9ac000 PC is at clear_page_dirty_for_io+0x1bc/0x1e8 LR is at clear_page_dirty_for_io+0x14/0x1e8 pc : [] lr : [] pstate: 40000145 sp : ffffffc02e9af4f0 Process kworker/u8:7 (pid: 31525, stack limit = 0xffffffc02e9ac020) Call trace: [] clear_page_dirty_for_io+0x1bc/0x1e8 [] extent_clear_unlock_delalloc+0x1e4/0x210 [btrfs] [] run_delalloc_nocow+0x3b8/0x948 [btrfs] [] run_delalloc_range+0x250/0x3a8 [btrfs] [] writepage_delalloc.isra.21+0xbc/0x1d8 [btrfs] [] __extent_writepage+0xe8/0x248 [btrfs] [] extent_write_cache_pages.isra.17+0x164/0x378 [btrfs] [] extent_writepages+0x48/0x68 [btrfs] [] btrfs_writepages+0x20/0x30 [btrfs] [] do_writepages+0x30/0x88 [] __writeback_single_inode+0x34/0x198 [] writeback_sb_inodes+0x184/0x3c0 [] __writeback_inodes_wb+0x6c/0xc0 [] wb_writeback+0x1b8/0x1c0 [] wb_workfn+0x150/0x250 [] process_one_work+0x1dc/0x388 [] worker_thread+0x130/0x500 [] kthread+0x10c/0x110 [] ret_from_fork+0x10/0x40 Code: d503201f a9025bb5 a90363b7 f90023b9 (d4210000) Reviewed-by: Filipe Manana Signed-off-by: Robbie Ko Signed-off-by: David Sterba [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- fs/btrfs/inode.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'fs/btrfs') diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 1b11bf89c139..67e036ccb63d 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -1449,12 +1449,11 @@ out_check: } btrfs_release_path(path); - if (cur_offset <= end && cow_start == (u64)-1) { + if (cur_offset <= end && cow_start == (u64)-1) cow_start = cur_offset; - cur_offset = end; - } if (cow_start != (u64)-1) { + cur_offset = end; ret = cow_file_range(inode, locked_page, cow_start, end, page_started, nr_written, 1); if (ret) -- cgit v1.2.3