| Message ID | 20221009090720.1040633-9-senozhatsky@chromium.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | zram: Support multiple compression streams | expand |
On Sun, 9 Oct 2022 18:07:20 +0900 Sergey Senozhatsky <senozhatsky@chromium.org> wrote: > Trivial comment typos fixes. > > --- a/drivers/block/zram/zram_drv.c > +++ b/drivers/block/zram/zram_drv.c > @@ -759,7 +759,7 @@ static ssize_t writeback_store(struct device *dev, > zram_slot_unlock(zram, index); > /* > * Return last IO error unless every IO were > - * not suceeded. > + * not succeeded. That's a pretty awkward sentence. Why not "unless every IO failed". If that's indeed what we're doing here. Sounds odd. What do we return if all IOs indeed failed?
On (22/10/17 17:08), Andrew Morton wrote: > On Sun, 9 Oct 2022 18:07:20 +0900 Sergey Senozhatsky <senozhatsky@chromium.org> wrote: > > > Trivial comment typos fixes. > > > > --- a/drivers/block/zram/zram_drv.c > > +++ b/drivers/block/zram/zram_drv.c > > @@ -759,7 +759,7 @@ static ssize_t writeback_store(struct device *dev, > > zram_slot_unlock(zram, index); > > /* > > * Return last IO error unless every IO were > > - * not suceeded. > > + * not succeeded. > > That's a pretty awkward sentence. Why not "unless every IO failed". > > If that's indeed what we're doing here. Sounds odd. What do we return > if all IOs indeed failed? Hmm, yes, I didn't consider re-phrasing this comment but we probably should do so. What we have there is while (nr_pages_to_write--) { err = submit_bio_wait(); if (err) { ret = err; continue; } } return ret; zram objects are independent and bio errors on individual writes are non-fatal, if we failed to write-back a zram object (page) we just continue and try to write the next one; at the same time we need to signal user-space that some of those writes failed (doesn't matter which ones or how many). That loop used to look as follows (as far as I can tell): while (nr_pages_to_write--) { ret = submit_bio_wait(); } return ret; Notice how `ret' would get overwritten all the time, so we if we had, say, a successful submit_bio_wait, then an unsuccessful one and a successful one again, we would lose the track of the bio error that happened on the second iteration and will always return 0 to user-space. *Unless* the last (or all) submit_bio_wait() also failed, in which case `ret' would hold the correct error code. Will something like this look less awkward to you? --- diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index ecbc5963b5b8..23f1655b7837 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -758,8 +758,12 @@ static ssize_t writeback_store(struct device *dev, zram_clear_flag(zram, index, ZRAM_IDLE); zram_slot_unlock(zram, index); /* - * Return last IO error unless every IO were - * not succeeded. + * BIO errors are not fatal, we continue and simply + * attempt to writeback the remaining objects (pages). + * At the same time we need to signal user-space that + * some writes (at least one, but also could be all of + * them) were not successful and we do so by returning + * the most recent BIO error. */ ret = err; continue;
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 34bb21691cee..ecbc5963b5b8 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -759,7 +759,7 @@ static ssize_t writeback_store(struct device *dev, zram_slot_unlock(zram, index); /* * Return last IO error unless every IO were - * not suceeded. + * not succeeded. */ ret = err; continue; @@ -1658,7 +1658,7 @@ static int zram_recompress(struct zram *zram, u32 index, struct page *page, /* * Either a compression error or we failed to compressed the object * in a way that will save us memory. Mark the object so that we - * don't attemp to re-compress it again (RECOMP_SKIP). + * don't attempt to re-compress it again (RECOMP_SKIP). */ if (comp_len_next >= huge_class_size || comp_len_next >= comp_len_prev ||
Trivial comment typos fixes. Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org> --- drivers/block/zram/zram_drv.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)