diff options
authorLinus Torvalds <torvalds@linux-foundation.org>2018-08-03 12:22:09 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-08-04 18:19:55 -0700
commita32e236eb93e62a0f692e79b7c3c9636689559b9 (patch)
parent0b5b1f9a78b5e1bb3c3972fcd27dc013367550f8 (diff)
Partially revert "block: fail op_is_write() requests to read-only partitions"
It turns out that commit 721c7fc701c7 ("block: fail op_is_write() requests to read-only partitions"), while obviously correct, causes problems for some older lvm2 installations. The reason is that the lvm snapshotting will continue to write to the snapshow COW volume, even after the volume has been marked read-only. End result: snapshot failure. This has actually been fixed in newer version of the lvm2 tool, but the old tools still exist, and the breakage was reported both in the kernel bugzilla and in the Debian bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=200439 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=900442 The lvm2 fix is here https://sourceware.org/git/?p=lvm2.git;a=commit;h=a6fdb9d9d70f51c49ad11a87ab4243344e6701a3 but until everybody has updated to recent versions, we'll have to weaken the "never write to read-only partitions" check. It now allows the write to happen, but causes a warning, something like this: generic_make_request: Trying to write to read-only block-device dm-3 (partno X) Modules linked in: nf_tables xt_cgroup xt_owner kvm_intel iwlmvm kvm irqbypass iwlwifi CPU: 1 PID: 77 Comm: kworker/1:1 Not tainted 4.17.9-gentoo #3 Hardware name: LENOVO 20B6A019RT/20B6A019RT, BIOS GJET91WW (2.41 ) 09/21/2016 Workqueue: ksnaphd do_metadata RIP: 0010:generic_make_request_checks+0x4ac/0x600 ... Call Trace: generic_make_request+0x64/0x400 submit_bio+0x6c/0x140 dispatch_io+0x287/0x430 sync_io+0xc3/0x120 dm_io+0x1f8/0x220 do_metadata+0x1d/0x30 process_one_work+0x1b9/0x3e0 worker_thread+0x2b/0x3c0 kthread+0x113/0x130 ret_from_fork+0x35/0x40 Note that this is a "revert" in behavior only. I'm leaving alone the actual code cleanups in commit 721c7fc701c7, but letting the previously uncaught request go through with a warning instead of stopping it. Fixes: 721c7fc701c7 ("block: fail op_is_write() requests to read-only partitions") Reported-and-tested-by: WGH <wgh@torlan.ru> Acked-by: Mike Snitzer <snitzer@redhat.com> Cc: Sagi Grimberg <sagi@grimberg.me> Cc: Ilya Dryomov <idryomov@gmail.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Zdenek Kabelac <zkabelac@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 files changed, 3 insertions, 2 deletions
diff --git a/block/blk-core.c b/block/blk-core.c
index f84a9b7b6f5a..ee33590f54eb 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2155,11 +2155,12 @@ static inline bool bio_check_ro(struct bio *bio, struct hd_struct *part)
if (part->policy && op_is_write(bio_op(bio))) {
- printk(KERN_ERR
"generic_make_request: Trying to write "
"to read-only block-device %s (partno %d)\n",
bio_devname(bio, b), part->partno);
- return true;
+ /* Older lvm-tools actually trigger this */
+ return false;
return false;