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From: robbieko <robbieko@synology.com>
To: linux-btrfs@vger.kernel.org
Cc: Robbie Ko <robbieko@synology.com>
Subject: [PATCH] Btrfs: fix cur_offset in the error case for nocow
Date: Tue, 30 Oct 2018 18:04:04 +0800	[thread overview]
Message-ID: <1540893844-3480-1-git-send-email-robbieko@synology.com> (raw)

From: Robbie Ko <robbieko@synology.com>

When the cow_file_range fail, 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.

------------[ cut here ]------------
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)
---[ end trace 65fecee7c2296f25 ]---

Signed-off-by: Robbie Ko <robbieko@synology.com>
---
 fs/btrfs/inode.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 181c58b..b62299b 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1532,10 +1532,10 @@ static noinline int run_delalloc_nocow(struct inode *inode,
 
 	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, end,
 				     page_started, nr_written, 1, NULL);
 		if (ret)
-- 
1.9.1


             reply	other threads:[~2018-10-30 10:04 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-30 10:04 robbieko [this message]
2018-10-30 11:45 ` [PATCH] Btrfs: fix cur_offset in the error case for nocow Filipe Manana
2018-10-30 16:31 ` David Sterba

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