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Date: Thu, 4 Sep 2014 10:39:44 +0900
From: Minchan Kim <minchan@...nel.org>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
Hugh Dickins <hughd@...gle.com>, Shaohua Li <shli@...nel.org>,
Jerome Marchand <jmarchan@...hat.com>,
Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
Dan Streetman <ddstreet@...e.org>,
Nitin Gupta <ngupta@...are.org>,
Luigi Semenzato <semenzato@...gle.com>,
Minchan Kim <minchan@...nel.org>
Subject: [RFC 1/3] zram: generalize swap_slot_free_notify
Currently, swap_slot_free_notify is used for zram to free
duplicated copy page for memory efficiency when it knows
there is no reference to the swap slot.
Let's extend it to be able to use it for other purpose
so this patch generalizes it so that zram can get more hints
from VM.
Signed-off-by: Minchan Kim <minchan@...nel.org>
---
Documentation/filesystems/Locking | 7 ++-----
drivers/block/zram/zram_drv.c | 18 ++++++++++++++++--
include/linux/blkdev.h | 7 +++++--
mm/page_io.c | 7 ++++---
mm/swapfile.c | 7 ++++---
5 files changed, 31 insertions(+), 15 deletions(-)
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index f1997e9da61f..e7133874fd75 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -405,7 +405,7 @@ prototypes:
void (*unlock_native_capacity) (struct gendisk *);
int (*revalidate_disk) (struct gendisk *);
int (*getgeo)(struct block_device *, struct hd_geometry *);
- void (*swap_slot_free_notify) (struct block_device *, unsigned long);
+ int (*swap_hint) (struct block_device *, unsigned int, void *);
locking rules:
bd_mutex
@@ -418,14 +418,11 @@ media_changed: no
unlock_native_capacity: no
revalidate_disk: no
getgeo: no
-swap_slot_free_notify: no (see below)
+swap_hint: no
media_changed, unlock_native_capacity and revalidate_disk are called only from
check_disk_change().
-swap_slot_free_notify is called with swap_lock and sometimes the page lock
-held.
-
--------------------------- file_operations -------------------------------
prototypes:
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index be88d750b112..88661d62e46a 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -933,7 +933,8 @@ error:
bio_io_error(bio);
}
-static void zram_slot_free_notify(struct block_device *bdev,
+/* this callback is with swap_lock and sometimes page table lock held */
+static int zram_slot_free_notify(struct block_device *bdev,
unsigned long index)
{
struct zram *zram;
@@ -946,10 +947,23 @@ static void zram_slot_free_notify(struct block_device *bdev,
zram_free_page(zram, index);
bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
atomic64_inc(&zram->stats.notify_free);
+
+ return 0;
+}
+
+static int zram_swap_hint(struct block_device *bdev,
+ unsigned int hint, void *arg)
+{
+ int ret = -EINVAL;
+
+ if (hint == SWAP_SLOT_FREE)
+ ret = zram_slot_free_notify(bdev, (unsigned long)arg);
+
+ return ret;
}
static const struct block_device_operations zram_devops = {
- .swap_slot_free_notify = zram_slot_free_notify,
+ .swap_hint = zram_swap_hint,
.owner = THIS_MODULE
};
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 518b46555b80..17437b2c18e4 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1609,6 +1609,10 @@ static inline bool blk_integrity_is_initialized(struct gendisk *g)
#endif /* CONFIG_BLK_DEV_INTEGRITY */
+enum swap_blk_hint {
+ SWAP_SLOT_FREE,
+};
+
struct block_device_operations {
int (*open) (struct block_device *, fmode_t);
void (*release) (struct gendisk *, fmode_t);
@@ -1624,8 +1628,7 @@ struct block_device_operations {
void (*unlock_native_capacity) (struct gendisk *);
int (*revalidate_disk) (struct gendisk *);
int (*getgeo)(struct block_device *, struct hd_geometry *);
- /* this callback is with swap_lock and sometimes page table lock held */
- void (*swap_slot_free_notify) (struct block_device *, unsigned long);
+ int (*swap_hint)(struct block_device *, unsigned int, void *);
struct module *owner;
};
diff --git a/mm/page_io.c b/mm/page_io.c
index 955db8b0d497..88a13d74c621 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -114,7 +114,7 @@ void end_swap_bio_read(struct bio *bio, int err)
* we again wish to reclaim it.
*/
struct gendisk *disk = sis->bdev->bd_disk;
- if (disk->fops->swap_slot_free_notify) {
+ if (disk->fops->swap_hint) {
swp_entry_t entry;
unsigned long offset;
@@ -122,8 +122,9 @@ void end_swap_bio_read(struct bio *bio, int err)
offset = swp_offset(entry);
SetPageDirty(page);
- disk->fops->swap_slot_free_notify(sis->bdev,
- offset);
+ disk->fops->swap_hint(sis->bdev,
+ SWAP_SLOT_FREE,
+ (void *)offset);
}
}
}
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 8798b2e0ac59..4bff521e649a 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -816,9 +816,10 @@ static unsigned char swap_entry_free(struct swap_info_struct *p,
frontswap_invalidate_page(p->type, offset);
if (p->flags & SWP_BLKDEV) {
struct gendisk *disk = p->bdev->bd_disk;
- if (disk->fops->swap_slot_free_notify)
- disk->fops->swap_slot_free_notify(p->bdev,
- offset);
+ if (disk->fops->swap_hint)
+ disk->fops->swap_hint(p->bdev,
+ SWAP_SLOT_FREE,
+ (void *)offset);
}
}
--
2.0.0
--
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