| Message ID | 20201231162845.1853347-1-mfo@canonical.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | loop: fix I/O error on fsync() in detached loop devices | expand |
Mauricio Faria de Oliveira <mfo@canonical.com> writes: > There's an I/O error on fsync() in a detached loop device > if it has been previously attached. > > The issue is write cache is enabled in the attach path in > loop_configure() but it isn't disabled in the detach path; > thus it remains enabled in the block device regardless of > whether it is attached or not. > > Now fsync() can get an I/O request that will just be failed > later in loop_queue_rq() as device's state is not 'Lo_bound'. > > So, disable write cache in the detach path. > > Test-case: > > # DEV=/dev/loop7 > > # IMG=/tmp/image > # truncate --size 1M $IMG > > # losetup $DEV $IMG > # losetup -d $DEV > > Before: > > # strace -e fsync parted -s $DEV print 2>&1 | grep fsync > fsync(3) = -1 EIO (Input/output error) > Warning: Error fsyncing/closing /dev/loop7: Input/output error > [ 982.529929] blk_update_request: I/O error, dev loop7, sector 0 op 0x1:(WRITE) flags 0x800 phys_seg 0 prio class 0 > > After: > > # strace -e fsync parted -s $DEV print 2>&1 | grep fsync > fsync(3) = 0 > > Signed-off-by: Mauricio Faria de Oliveira <mfo@canonical.com> > Co-developed-by: Eric Desrochers <eric.desrochers@canonical.com> > Signed-off-by: Eric Desrochers <eric.desrochers@canonical.com> This sign-off chain is not sorted correctly. See Documentation/process/submitting-patches.rst. Other than that, I think the fix makes sense. Tested-by: Gabriel Krisman Bertazi <krisman@collabora.com> > --- > drivers/block/loop.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/block/loop.c b/drivers/block/loop.c > index e5ff328f0917..49517482e061 100644 > --- a/drivers/block/loop.c > +++ b/drivers/block/loop.c > @@ -1212,6 +1212,9 @@ static int __loop_clr_fd(struct loop_device *lo, bool release) > goto out_unlock; > } > > + if (!(lo->lo_flags & LO_FLAGS_READ_ONLY) && filp->f_op->fsync) > + blk_queue_write_cache(lo->lo_queue, false, false); > + > /* freeze request queue during the transition */ > blk_mq_freeze_queue(lo->lo_queue);
On Sat, Jan 2, 2021 at 2:14 AM Gabriel Krisman Bertazi <krisman@collabora.com> wrote: > > Mauricio Faria de Oliveira <mfo@canonical.com> writes: [snip] > > Signed-off-by: Mauricio Faria de Oliveira <mfo@canonical.com> > > Co-developed-by: Eric Desrochers <eric.desrochers@canonical.com> > > Signed-off-by: Eric Desrochers <eric.desrochers@canonical.com> > > This sign-off chain is not sorted correctly. See Documentation/process/submitting-patches.rst. > > Other than that, I think the fix makes sense. > > Tested-by: Gabriel Krisman Bertazi <krisman@collabora.com> > Hey Krisman, Thanks for testing and catching that; sent V2. [snip] > -- > Gabriel Krisman Bertazi cheers,
diff --git a/drivers/block/loop.c b/drivers/block/loop.c index e5ff328f0917..49517482e061 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -1212,6 +1212,9 @@ static int __loop_clr_fd(struct loop_device *lo, bool release) goto out_unlock; } + if (!(lo->lo_flags & LO_FLAGS_READ_ONLY) && filp->f_op->fsync) + blk_queue_write_cache(lo->lo_queue, false, false); + /* freeze request queue during the transition */ blk_mq_freeze_queue(lo->lo_queue);
There's an I/O error on fsync() in a detached loop device if it has been previously attached. The issue is write cache is enabled in the attach path in loop_configure() but it isn't disabled in the detach path; thus it remains enabled in the block device regardless of whether it is attached or not. Now fsync() can get an I/O request that will just be failed later in loop_queue_rq() as device's state is not 'Lo_bound'. So, disable write cache in the detach path. Test-case: # DEV=/dev/loop7 # IMG=/tmp/image # truncate --size 1M $IMG # losetup $DEV $IMG # losetup -d $DEV Before: # strace -e fsync parted -s $DEV print 2>&1 | grep fsync fsync(3) = -1 EIO (Input/output error) Warning: Error fsyncing/closing /dev/loop7: Input/output error [ 982.529929] blk_update_request: I/O error, dev loop7, sector 0 op 0x1:(WRITE) flags 0x800 phys_seg 0 prio class 0 After: # strace -e fsync parted -s $DEV print 2>&1 | grep fsync fsync(3) = 0 Signed-off-by: Mauricio Faria de Oliveira <mfo@canonical.com> Co-developed-by: Eric Desrochers <eric.desrochers@canonical.com> Signed-off-by: Eric Desrochers <eric.desrochers@canonical.com> --- drivers/block/loop.c | 3 +++ 1 file changed, 3 insertions(+)