Messages in this thread | | | From | OGAWA Hirofumi <> | Subject | Re: [PATCH] Fix queueing work if !bdi_cap_writeback_dirty() | Date | Thu, 13 Sep 2012 16:53:58 +0900 |
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Fengguang Wu <fengguang.wu@intel.com> writes:
> On Wed, Sep 12, 2012 at 03:28:42AM +0900, OGAWA Hirofumi wrote: >> >> If bdi has BDI_CAP_NO_WRITEBACK, bdi_forker_thread() doesn't start >> writeback thread. This means there is no consumer of work item made >> by bdi_queue_work(). >> >> This adds to checking of !bdi_cap_writeback_dirty(sb->s_bdi) before >> calling bdi_queue_work(), otherwise queued work never be consumed. >> >> Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> >> --- >> >> fs/fs-writeback.c | 7 +++++-- >> 1 file changed, 5 insertions(+), 2 deletions(-) >> >> diff -puN fs/fs-writeback.c~noop_backing_dev_info-check-fix fs/fs-writeback.c >> --- linux/fs/fs-writeback.c~noop_backing_dev_info-check-fix 2012-09-11 06:12:30.000000000 +0900 >> +++ linux-hirofumi/fs/fs-writeback.c 2012-09-11 06:12:30.000000000 +0900 >> @@ -120,6 +120,9 @@ __bdi_start_writeback(struct backing_dev >> { >> struct wb_writeback_work *work; >> >> + if (!bdi_cap_writeback_dirty(bdi)) >> + return; > > Will someone in the current kernel actually call > __bdi_start_writeback() on a BDI_CAP_NO_WRITEBACK bdi? > > If the answer is no, VM_BUG_ON(!bdi_cap_writeback_dirty(bdi)) looks better.
I guess nobody call it in current kernel though. Hmm.., but we also have check in __mark_inode_dirty(), nobody should be using it, right?
If we defined it as the bug, I can't see what BDI_CAP_NO_WRITEBACK wants to do actually. We are not going to allow to disable the writeback task?
I was going to use this to disable writeback task on my developing FS...
Thanks. -- OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
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