This is a note to let you know that I've just added the patch titled
Btrfs: fix list_add corruption and soft lockups in fsync
to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
btrfs-fix-list_add-corruption-and-soft-lockups-in-fsync.patch
and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Thu Feb 1 13:45:42 CET 2018
From: Liu Bo <bo.li.liu@xxxxxxxxxx>
Date: Tue, 21 Nov 2017 14:35:40 -0700
Subject: Btrfs: fix list_add corruption and soft lockups in fsync
From: Liu Bo <bo.li.liu@xxxxxxxxxx>
[ Upstream commit ebb70442cdd4872260c2415929c456be3562da82 ]
Xfstests btrfs/146 revealed this corruption,
[ 58.138831] Buffer I/O error on dev dm-0, logical block 2621424, async page read
[ 58.151233] BTRFS error (device sdf): bdev /dev/mapper/error-test errs: wr 1, rd 0, flush 0, corrupt 0, gen 0
[ 58.152403] list_add corruption. prev->next should be next (ffff88005e6775d8), but was ffffc9000189be88. (prev=ffffc9000189be88).
[ 58.153518] ------------[ cut here ]------------
[ 58.153892] WARNING: CPU: 1 PID: 1287 at lib/list_debug.c:31 __list_add_valid+0x169/0x1f0
...
[ 58.157379] RIP: 0010:__list_add_valid+0x169/0x1f0
...
[ 58.161956] Call Trace:
[ 58.162264] btrfs_log_inode_parent+0x5bd/0xfb0 [btrfs]
[ 58.163583] btrfs_log_dentry_safe+0x60/0x80 [btrfs]
[ 58.164003] btrfs_sync_file+0x4c2/0x6f0 [btrfs]
[ 58.164393] vfs_fsync_range+0x5f/0xd0
[ 58.164898] do_fsync+0x5a/0x90
[ 58.165170] SyS_fsync+0x10/0x20
[ 58.165395] entry_SYSCALL_64_fastpath+0x1f/0xbe
...
It turns out that we could record btrfs_log_ctx:io_err in
log_one_extents when IO fails, but make log_one_extents() return '0'
instead of -EIO, so the IO error is not acknowledged by the callers,
i.e. btrfs_log_inode_parent(), which would remove btrfs_log_ctx:list
from list head 'root->log_ctxs'. Since btrfs_log_ctx is allocated
from stack memory, it'd get freed with a object alive on the
list. then a future list_add will throw the above warning.
This returns the correct error in the above case.
Jeff also reported this while testing against his fsync error
patch set[1].
[1]: https://www.spinics.net/lists/linux-btrfs/msg65308.html
"btrfs list corruption and soft lockups while testing writeback error handling"
Fixes: 8407f553268a4611f254 ("Btrfs: fix data corruption after fast fsync and writeback error")
Signed-off-by: Liu Bo <bo.li.liu@xxxxxxxxxx>
Reviewed-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/btrfs/file.c | 5 +++--
fs/btrfs/tree-log.c | 2 +-
2 files changed, 4 insertions(+), 3 deletions(-)
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -2056,6 +2056,8 @@ int btrfs_sync_file(struct file *file, l
len = (u64)end - (u64)start + 1;
trace_btrfs_sync_file(file, datasync);
+ btrfs_init_log_ctx(&ctx, inode);
+
/*
* We write the dirty pages in the range and wait until they complete
* out of the ->i_mutex. If so, we can flush the dirty pages by
@@ -2202,8 +2204,6 @@ int btrfs_sync_file(struct file *file, l
}
trans->sync = true;
- btrfs_init_log_ctx(&ctx, inode);
-
ret = btrfs_log_dentry_safe(trans, root, dentry, start, end, &ctx);
if (ret < 0) {
/* Fallthrough and commit/free transaction. */
@@ -2261,6 +2261,7 @@ int btrfs_sync_file(struct file *file, l
ret = btrfs_end_transaction(trans);
}
out:
+ ASSERT(list_empty(&ctx.list));
err = file_check_and_advance_wb_err(file);
if (!ret)
ret = err;
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -4100,7 +4100,7 @@ static int log_one_extent(struct btrfs_t
if (ordered_io_err) {
ctx->io_err = -EIO;
- return 0;
+ return ctx->io_err;
}
btrfs_init_map_token(&token);
Patches currently in stable-queue which might be from bo.li.liu@xxxxxxxxxx are
queue-4.14/btrfs-bail-out-gracefully-rather-than-bug_on.patch
queue-4.14/btrfs-fix-deadlock-when-writing-out-space-cache.patch
queue-4.14/btrfs-fix-list_add-corruption-and-soft-lockups-in-fsync.patch