+ zram-fix-synchronous-reads-fix.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: zram-fix-synchronous-reads-fix
has been added to the -mm mm-unstable branch.  Its filename is
     zram-fix-synchronous-reads-fix.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/zram-fix-synchronous-reads-fix.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Christoph Hellwig <hch@lst.de>
Subject: zram-fix-synchronous-reads-fix
Date: Fri, 7 Apr 2023 09:22:24 +0200

turns out this doesn't even compile for PAGE_SIZE > 4096.

Below is the fix, which also removes the #if and instead relies
on compiler dead code elimination.  I wonder if zram should (maybe
optionally) also offer a 512 byte block size, so that we could
also test the smaller than page size I/O path even on x86.

Link: https://lkml.kernel.org/r/20230407072224.GA8982@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/block/zram/zram_drv.c |   14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

--- a/drivers/block/zram/zram_drv.c~zram-fix-synchronous-reads-fix
+++ a/drivers/block/zram/zram_drv.c
@@ -764,7 +764,6 @@ release_init_lock:
 	return ret;
 }
 
-#if PAGE_SIZE != 4096
 struct zram_work {
 	struct work_struct work;
 	struct zram *zram;
@@ -775,7 +774,7 @@ struct zram_work {
 static void zram_sync_read(struct work_struct *work)
 {
 	struct zram_work *zw = container_of(work, struct zram_work, work);
-	struct bio_bvec bv;
+	struct bio_vec bv;
 	struct bio bio;
 
 	bio_init(&bio, zw->zram->bdev, &bv, 1, REQ_OP_READ);
@@ -794,6 +793,9 @@ static int read_from_bdev_sync(struct zr
 {
 	struct zram_work work;
 
+	if (WARN_ON_ONCE(PAGE_SIZE != 4096))
+		return -EIO;
+
 	work.page = page;
 	work.zram = zram;
 	work.entry = entry;
@@ -805,14 +807,6 @@ static int read_from_bdev_sync(struct zr
 
 	return 1;
 }
-#else
-static int read_from_bdev_sync(struct zram *zram, struct page *page,
-				unsigned long entry)
-{
-	WARN_ON(1);
-	return -EIO;
-}
-#endif
 
 static int read_from_bdev(struct zram *zram, struct page *page,
 			unsigned long entry, struct bio *parent)
_

Patches currently in -mm which might be from hch@lst.de are

zram-remove-valid_io_request.patch
zram-make-zram_bio_discard-more-self-contained.patch
zram-simplify-bvec-iteration-in-__zram_make_request.patch
zram-move-discard-handling-to-zram_submit_bio.patch
zram-return-early-on-error-in-zram_bvec_rw.patch
zram-refactor-highlevel-read-and-write-handling.patch
zram-dont-use-highmem-for-the-bounce-buffer-in-zram_bvec_readwrite.patch
zram-rename-__zram_bvec_read-to-zram_read_page.patch
zram-directly-call-zram_read_page-in-writeback_store.patch
zram-refactor-zram_bdev_read.patch
zram-dont-pass-a-bvec-to-__zram_bvec_write.patch
zram-refactor-zram_bdev_write.patch
zram-pass-a-page-to-read_from_bdev.patch
zram-dont-return-errors-from-read_from_bdev_async.patch
zram-fix-synchronous-reads.patch
zram-fix-synchronous-reads-fix.patch
zram-return-errors-from-read_from_bdev_sync.patch