Hi Chao,
Can you please help review below diff given by Jaegeuk?
If it looks good, I can send a v2.
Thanks,
On Thu, May 28, 2020 at 12:18:39PM -0700, Jaegeuk Kim wrote:
> On 05/28, Chao Yu wrote:
> > On 2020/5/28 10:45, Chao Yu wrote:
> > > On 2020/5/27 10:20, Sahitya Tummala wrote:
> > >> In case a compressed file is getting overwritten, the current retry
> > >> logic doesn't include the current page to be retried now as it sets
> > >> the new start index as 0 and new end index as writeback_index - 1.
> > >> This causes the corresponding cluster to be uncompressed and written
> > >> as normal pages without compression. Fix this by allowing writeback to
> > >> be retried for the current page as well (in case of compressed page
> > >> getting retried due to index mismatch with cluster index). So that
> > >> this cluster can be written compressed in case of overwrite.
> > >>
> > >> Signed-off-by: Sahitya Tummala <stumm...@codeaurora.org>
> > >> ---
> > >> fs/f2fs/data.c | 2 +-
> > >> 1 file changed, 1 insertion(+), 1 deletion(-)
> > >>
> > >> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> > >> index 4af5fcd..bfd1df4 100644
> > >> --- a/fs/f2fs/data.c
> > >> +++ b/fs/f2fs/data.c
> > >> @@ -3024,7 +3024,7 @@ static int f2fs_write_cache_pages(struct
> > >> address_space *mapping,
> > >> if ((!cycled && !done) || retry) {
> > >
> > > IMO, we add retry logic in wrong place, you can see that cycled value is
> > > zero only if wbc->range_cyclic is true, in that case writeback_index is
> > > valid.
> > >
> > > However if retry is true and wbc->range_cyclic is false, then
> > > writeback_index
> > > would be uninitialized variable.
> > >
> > > Thoughts?
> > >
> > > Thanks,
> > >
> > >> cycled = 1;
> > >> index = 0;
> > >> - end = writeback_index - 1;
> >
> > BTW, I notice that range_cyclic writeback flow was refactored in below
> > commit,
> > and skeleton of f2fs.writepages was copied from
> > mm/page-writeback.c::write_cache_pages(),
> > I guess we need follow that change.
> >
> > 64081362e8ff ("mm/page-writeback.c: fix range_cyclic writeback vs
> > writepages deadlock")
>
> Is that something like this?
>
> ---
> fs/f2fs/data.c | 11 ++---------
> 1 file changed, 2 insertions(+), 9 deletions(-)
>
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 48a622b95b76e..28fcdf0d4dcb9 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -2861,7 +2861,6 @@ static int f2fs_write_cache_pages(struct address_space
> *mapping,
> pgoff_t index;
> pgoff_t end; /* Inclusive */
> pgoff_t done_index;
> - int cycled;
> int range_whole = 0;
> xa_mark_t tag;
> int nwritten = 0;
> @@ -2879,17 +2878,12 @@ static int f2fs_write_cache_pages(struct
> address_space *mapping,
> if (wbc->range_cyclic) {
> writeback_index = mapping->writeback_index; /* prev offset */
> index = writeback_index;
> - if (index == 0)
> - cycled = 1;
> - else
> - cycled = 0;
> end = -1;
> } else {
> index = wbc->range_start >> PAGE_SHIFT;
> end = wbc->range_end >> PAGE_SHIFT;
> if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
> range_whole = 1;
> - cycled = 1; /* ignore range_cyclic tests */
> }
> if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
> tag = PAGECACHE_TAG_TOWRITE;
> @@ -3054,10 +3048,9 @@ static int f2fs_write_cache_pages(struct address_space
> *mapping,
> }
> }
> #endif
> - if ((!cycled && !done) || retry) {
> - cycled = 1;
> + if (retry) {
> index = 0;
> - end = writeback_index - 1;
> + end = -1;
> goto retry;
> }
> if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
> --
> 2.27.0.rc0.183.gde8f92d652-goog
>
--
--
Sent by a consultant of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.
