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author | Qu Wenruo <wqu@suse.com> | 2023-06-01 13:51:34 +0300 |
---|---|---|
committer | David Sterba <dsterba@suse.com> | 2023-06-01 16:12:02 +0300 |
commit | b675df0257bb717082f592626da3ddfc5bdc2b6b (patch) | |
tree | 4634d902e3ae0a489520fc9d22da8799dfe1ea2a /net | |
parent | 5ad9b4719fc9bc4715c7e19875a962095b0577e7 (diff) | |
download | linux-b675df0257bb717082f592626da3ddfc5bdc2b6b.tar.xz |
btrfs: zoned: fix dev-replace after the scrub rework
[BUG]
After commit e02ee89baa66 ("btrfs: scrub: switch scrub_simple_mirror()
to scrub_stripe infrastructure"), scrub no longer works for zoned device
at all.
Even an empty zoned btrfs cannot be replaced:
# mkfs.btrfs -f /dev/nvme0n1
# mount /dev/nvme0n1 /mnt/btrfs
# btrfs replace start -Bf 1 /dev/nvme0n2 /mnt/btrfs
Resetting device zones /dev/nvme1n1 (160 zones) ...
ERROR: ioctl(DEV_REPLACE_START) failed on "/mnt/btrfs/": Input/output error
And we can hit kernel crash related to that:
BTRFS info (device nvme1n1): host-managed zoned block device /dev/nvme3n1, 160 zones of 134217728 bytes
BTRFS info (device nvme1n1): dev_replace from /dev/nvme2n1 (devid 2) to /dev/nvme3n1 started
nvme3n1: Zone Management Append(0x7d) @ LBA 65536, 4 blocks, Zone Is Full (sct 0x1 / sc 0xb9) DNR
I/O error, dev nvme3n1, sector 786432 op 0xd:(ZONE_APPEND) flags 0x4000 phys_seg 3 prio class 2
BTRFS error (device nvme1n1): bdev /dev/nvme3n1 errs: wr 1, rd 0, flush 0, corrupt 0, gen 0
BUG: kernel NULL pointer dereference, address: 00000000000000a8
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
RIP: 0010:_raw_spin_lock_irqsave+0x1e/0x40
Call Trace:
<IRQ>
btrfs_lookup_ordered_extent+0x31/0x190
btrfs_record_physical_zoned+0x18/0x40
btrfs_simple_end_io+0xaf/0xc0
blk_update_request+0x153/0x4c0
blk_mq_end_request+0x15/0xd0
nvme_poll_cq+0x1d3/0x360
nvme_irq+0x39/0x80
__handle_irq_event_percpu+0x3b/0x190
handle_irq_event+0x2f/0x70
handle_edge_irq+0x7c/0x210
__common_interrupt+0x34/0xa0
common_interrupt+0x7d/0xa0
</IRQ>
<TASK>
asm_common_interrupt+0x22/0x40
[CAUSE]
Dev-replace reuses scrub code to iterate all extents and write the
existing content back to the new device.
And for zoned devices, we call fill_writer_pointer_gap() to make sure
all the writes into the zoned device is sequential, even if there may be
some gaps between the writes.
However we have several different bugs all related to zoned dev-replace:
- We are using ZONE_APPEND operation for metadata style write back
For zoned devices, btrfs has two ways to write data:
* ZONE_APPEND for data
This allows higher queue depth, but will not be able to know where
the write would land.
Thus needs to grab the real on-disk physical location in it's endio.
* WRITE for metadata
This requires single queue depth (new writes can only be submitted
after previous one finished), and all writes must be sequential.
For scrub, we go single queue depth, but still goes with ZONE_APPEND,
which requires btrfs_bio::inode being populated.
This is the cause of that crash.
- No correct tracing of write_pointer
After a write finished, we should forward sctx->write_pointer, or
fill_writer_pointer_gap() would not work properly and cause more
than necessary zero out, and fill the whole zone prematurely.
- Incorrect physical bytenr passed to fill_writer_pointer_gap()
In scrub_write_sectors(), one call site passes logical address, which
is completely wrong.
The other call site passes physical address of current sector, but
we should pass the physical address of the btrfs_bio we're submitting.
This is the cause of the -EIO errors.
[FIX]
- Do not use ZONE_APPEND for btrfs_submit_repair_write().
- Manually forward sctx->write_pointer after successful writeback
- Use the physical address of the to-be-submitted btrfs_bio for
fill_writer_pointer_gap()
Now zoned device replace would work as expected.
Reported-by: Christoph Hellwig <hch@lst.de>
Fixes: e02ee89baa66 ("btrfs: scrub: switch scrub_simple_mirror() to scrub_stripe infrastructure")
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'net')
0 files changed, 0 insertions, 0 deletions