The patch titled
Subject: zram: factor out WB and non-WB zram read functions
has been added to the -mm mm-unstable branch. Its filename is
zram-factor-out-wb-and-non-wb-zram-read-functions.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/zram-factor-out-wb-and-non-wb-zram-read-functions.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: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Subject: zram: factor out WB and non-WB zram read functions
Date: Sun, 9 Oct 2022 18:07:15 +0900
We will use non-WB variant in ZRAM page recompression path.
Link: https://lkml.kernel.org/r/20221009090720.1040633-4-senozhatsky@xxxxxxxxxxxx
Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Nitin Gupta <ngupta@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/block/zram/zram_drv.c | 73 +++++++++++++++++++++-----------
1 file changed, 50 insertions(+), 23 deletions(-)
--- a/drivers/block/zram/zram_drv.c~zram-factor-out-wb-and-non-wb-zram-read-functions
+++ a/drivers/block/zram/zram_drv.c
@@ -1314,8 +1314,30 @@ out:
~(1UL << ZRAM_LOCK | 1UL << ZRAM_UNDER_WB));
}
-static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index,
- struct bio *bio, bool partial_io)
+/*
+ * Reads a page from the writeback devices. Corresponding ZRAM slot
+ * should be unlocked.
+ */
+static int zram_read_from_writeback(struct zram *zram, struct page *page,
+ u32 index, struct bio *bio,
+ bool partial_io)
+{
+ struct bio_vec bvec;
+
+ bvec.bv_page = page;
+ bvec.bv_len = PAGE_SIZE;
+ bvec.bv_offset = 0;
+ return read_from_bdev(zram, &bvec,
+ zram_get_element(zram, index),
+ bio, partial_io);
+}
+
+/*
+ * Reads (decompresses if needed) a page from zspool (zsmalloc).
+ * Corresponding ZRAM slot should be locked.
+ */
+static int zram_read_from_zspool(struct zram *zram, struct page *page,
+ u32 index)
{
struct zcomp_strm *zstrm;
unsigned long handle;
@@ -1323,23 +1345,6 @@ static int __zram_bvec_read(struct zram
void *src, *dst;
int ret;
- zram_slot_lock(zram, index);
- if (zram_test_flag(zram, index, ZRAM_WB)) {
- struct bio_vec bvec;
-
- zram_slot_unlock(zram, index);
- /* A null bio means rw_page was used, we must fallback to bio */
- if (!bio)
- return -EOPNOTSUPP;
-
- bvec.bv_page = page;
- bvec.bv_len = PAGE_SIZE;
- bvec.bv_offset = 0;
- return read_from_bdev(zram, &bvec,
- zram_get_element(zram, index),
- bio, partial_io);
- }
-
handle = zram_get_handle(zram, index);
if (!handle || zram_test_flag(zram, index, ZRAM_SAME)) {
unsigned long value;
@@ -1349,7 +1354,6 @@ static int __zram_bvec_read(struct zram
mem = kmap_atomic(page);
zram_fill_page(mem, PAGE_SIZE, value);
kunmap_atomic(mem);
- zram_slot_unlock(zram, index);
return 0;
}
@@ -1371,17 +1375,40 @@ static int __zram_bvec_read(struct zram
zcomp_stream_put(zram->comps[ZRAM_PRIMARY_ZCOMP]);
}
zs_unmap_object(zram->mem_pool, handle);
- zram_slot_unlock(zram, index);
+ return ret;
+}
+
+static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index,
+ struct bio *bio, bool partial_io)
+{
+ int ret;
+
+ zram_slot_lock(zram, index);
+ if (!zram_test_flag(zram, index, ZRAM_WB)) {
+ /* Slot should be locked through out the function call */
+ ret = zram_read_from_zspool(zram, page, index);
+ zram_slot_unlock(zram, index);
+ } else {
+ /* Slot should be unlocked before the function call */
+ zram_slot_unlock(zram, index);
+
+ /* A null bio means rw_page was used, we must fallback to bio */
+ if (!bio)
+ return -EOPNOTSUPP;
+
+ ret = zram_read_from_writeback(zram, page, index, bio,
+ partial_io);
+ }
/* Should NEVER happen. Return bio error if it does. */
- if (WARN_ON(ret))
+ if (WARN_ON(ret < 0))
pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
return ret;
}
static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
- u32 index, int offset, struct bio *bio)
+ u32 index, int offset, struct bio *bio)
{
int ret;
struct page *page;
_
Patches currently in -mm which might be from senozhatsky@xxxxxxxxxxxx are
zram-preparation-for-multi-zcomp-support.patch
zram-add-recompression-algorithm-sysfs-knob.patch
zram-factor-out-wb-and-non-wb-zram-read-functions.patch
zram-introduce-recompress-sysfs-knob.patch
documentation-add-recompression-documentation.patch
zram-add-recompression-algorithm-choice-to-kconfig.patch
zram-add-recompress-flag-to-read_block_state.patch
zram-correct-typos.patch
