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UPSTREAM: zram: fix return value on writeback_store

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writeback_store's return value is overwritten by submit_bio_wait's return
value.  Thus, writeback_store will return zero since there was no IO
error.  In the end, write syscall from userspace will see the zero as
return value, which could make the process stall to keep trying the write
until it will succeed.

Link: https://lkml.kernel.org/r/20210312173949.2197662-1-minchan@kernel.org
Fixes: 3b82a051c101("drivers/block/zram/zram_drv.c: fix error return codes not being returned in writeback_store")
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Colin Ian King <colin.king@canonical.com>
Cc: John Dias <joaodias@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit 57e0076e65)

Bug: 182850185
Signed-off-by: Amos Bianchi <amosbianchi@google.com>
Change-Id: I7cbef91b62584826192b7ebdb434675a549a9801
This commit is contained in:
Minchan Kim
2021-03-12 21:08:38 -08:00
committed by Suren Baghdasaryan
parent 475aea007d
commit 542d1937ba
1 changed files with 8 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
drivers/block/zram/zram_drv.c
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@@ -637,7 +637,7 @@ static ssize_t writeback_store(struct device *dev,
struct bio_vec bio_vec; struct bio_vec bio_vec;
struct page *page; struct page *page;
ssize_t ret = len; ssize_t ret = len;
int mode; int mode, err;
unsigned long blk_idx = 0; unsigned long blk_idx = 0;
if (sysfs_streq(buf, "idle")) if (sysfs_streq(buf, "idle"))
@@ -738,12 +738,17 @@ static ssize_t writeback_store(struct device *dev,
* XXX: A single page IO would be inefficient for write * XXX: A single page IO would be inefficient for write
* but it would be not bad as starter. * but it would be not bad as starter.
*/ */
ret = submit_bio_wait(&bio); err = submit_bio_wait(&bio);
if (ret) { if (err) {
zram_slot_lock(zram, index); zram_slot_lock(zram, index);
zram_clear_flag(zram, index, ZRAM_UNDER_WB); zram_clear_flag(zram, index, ZRAM_UNDER_WB);
zram_clear_flag(zram, index, ZRAM_IDLE); zram_clear_flag(zram, index, ZRAM_IDLE);
zram_slot_unlock(zram, index); zram_slot_unlock(zram, index);
/*
* Return last IO error unless every IO were
* not suceeded.
*/
ret = err;
continue; continue;
} }