3.16.63-rc1 review patch. If anyone has any objections, please let me know.
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From: Robbie Ko robbieko@synology.com
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 : [<ffffffc00033c91c>] lr : [<ffffffc00033c774>] pstate: 40000145 sp : ffffffc02e9af4f0 Process kworker/u8:7 (pid: 31525, stack limit = 0xffffffc02e9ac020) Call trace: [<ffffffc00033c91c>] clear_page_dirty_for_io+0x1bc/0x1e8 [<ffffffbffc514674>] extent_clear_unlock_delalloc+0x1e4/0x210 [btrfs] [<ffffffbffc4fb168>] run_delalloc_nocow+0x3b8/0x948 [btrfs] [<ffffffbffc4fb948>] run_delalloc_range+0x250/0x3a8 [btrfs] [<ffffffbffc514c0c>] writepage_delalloc.isra.21+0xbc/0x1d8 [btrfs] [<ffffffbffc516048>] __extent_writepage+0xe8/0x248 [btrfs] [<ffffffbffc51630c>] extent_write_cache_pages.isra.17+0x164/0x378 [btrfs] [<ffffffbffc5185a8>] extent_writepages+0x48/0x68 [btrfs] [<ffffffbffc4f5828>] btrfs_writepages+0x20/0x30 [btrfs] [<ffffffc00033d758>] do_writepages+0x30/0x88 [<ffffffc0003ba0f4>] __writeback_single_inode+0x34/0x198 [<ffffffc0003ba6c4>] writeback_sb_inodes+0x184/0x3c0 [<ffffffc0003ba96c>] __writeback_inodes_wb+0x6c/0xc0 [<ffffffc0003bac20>] wb_writeback+0x1b8/0x1c0 [<ffffffc0003bb0f0>] wb_workfn+0x150/0x250 [<ffffffc0002b0014>] process_one_work+0x1dc/0x388 [<ffffffc0002b02f0>] worker_thread+0x130/0x500 [<ffffffc0002b6344>] kthread+0x10c/0x110 [<ffffffc000284590>] ret_from_fork+0x10/0x40 Code: d503201f a9025bb5 a90363b7 f90023b9 (d4210000)
Reviewed-by: Filipe Manana fdmanana@suse.com Signed-off-by: Robbie Ko robbieko@synology.com Signed-off-by: David Sterba dsterba@suse.com [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- fs/btrfs/inode.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)
--- 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)