The patch titled
Subject: zram: add free space management in backing device
has been added to the -mm tree. Its filename is
zram-add-free-space-management-in-backing-device.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/zram-add-free-space-management-in-backing-device.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/zram-add-free-space-management-in-backing-device.patch
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------------------------------------------------------
From: Minchan Kim <minchan@xxxxxxxxxx>
Subject: zram: add free space management in backing device
With backing device, zram needs management of free space of backing
device.
This patch adds bitmap logic to manage free space which is very naive.
However, it would be simple enough as considering uncompressible pages's
frequenty in zram.
Link: http://lkml.kernel.org/r/1498459987-24562-6-git-send-email-minchan@xxxxxxxxxx
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Juneho Choi <juno.choi@xxxxxxx>
Cc: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/block/zram/zram_drv.c | 48 +++++++++++++++++++++++++++++++-
drivers/block/zram/zram_drv.h | 3 ++
2 files changed, 50 insertions(+), 1 deletion(-)
diff -puN drivers/block/zram/zram_drv.c~zram-add-free-space-management-in-backing-device drivers/block/zram/zram_drv.c
--- a/drivers/block/zram/zram_drv.c~zram-add-free-space-management-in-backing-device
+++ a/drivers/block/zram/zram_drv.c
@@ -292,6 +292,9 @@ static void reset_bdev(struct zram *zram
zram->backing_dev = NULL;
zram->old_block_size = 0;
zram->bdev = NULL;
+
+ kvfree(zram->bitmap);
+ zram->bitmap = NULL;
}
static ssize_t backing_dev_show(struct device *dev,
@@ -330,7 +333,8 @@ static ssize_t backing_dev_store(struct
struct file *backing_dev = NULL;
struct inode *inode;
struct address_space *mapping;
- unsigned int old_block_size = 0;
+ unsigned int bitmap_sz, old_block_size = 0;
+ unsigned long nr_pages, *bitmap = NULL;
struct block_device *bdev = NULL;
int err;
struct zram *zram = dev_to_zram(dev);
@@ -369,16 +373,27 @@ static ssize_t backing_dev_store(struct
if (err < 0)
goto out;
+ nr_pages = i_size_read(inode) >> PAGE_SHIFT;
+ bitmap_sz = BITS_TO_LONGS(nr_pages) * sizeof(long);
+ bitmap = kvzalloc(bitmap_sz, GFP_KERNEL);
+ if (!bitmap) {
+ err = -ENOMEM;
+ goto out;
+ }
+
old_block_size = block_size(bdev);
err = set_blocksize(bdev, PAGE_SIZE);
if (err)
goto out;
reset_bdev(zram);
+ spin_lock_init(&zram->bitmap_lock);
zram->old_block_size = old_block_size;
zram->bdev = bdev;
zram->backing_dev = backing_dev;
+ zram->bitmap = bitmap;
+ zram->nr_pages = nr_pages;
up_write(&zram->init_lock);
pr_info("setup backing device %s\n", file_name);
@@ -386,6 +401,9 @@ static ssize_t backing_dev_store(struct
return len;
out:
+ if (bitmap)
+ kvfree(bitmap);
+
if (bdev)
blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
@@ -399,6 +417,34 @@ out:
return err;
}
+static unsigned long get_entry_bdev(struct zram *zram)
+{
+ unsigned long entry;
+
+ spin_lock(&zram->bitmap_lock);
+ /* skip 0 bit to confuse zram.handle = 0 */
+ entry = find_next_zero_bit(zram->bitmap, zram->nr_pages, 1);
+ if (entry == zram->nr_pages) {
+ spin_unlock(&zram->bitmap_lock);
+ return 0;
+ }
+
+ set_bit(entry, zram->bitmap);
+ spin_unlock(&zram->bitmap_lock);
+
+ return entry;
+}
+
+static void put_entry_bdev(struct zram *zram, unsigned long entry)
+{
+ int was_set;
+
+ spin_lock(&zram->bitmap_lock);
+ was_set = test_and_clear_bit(entry, zram->bitmap);
+ spin_unlock(&zram->bitmap_lock);
+ WARN_ON_ONCE(!was_set);
+}
+
#else
static bool zram_wb_enabled(struct zram *zram) { return false; }
static inline void reset_bdev(struct zram *zram) {};
diff -puN drivers/block/zram/zram_drv.h~zram-add-free-space-management-in-backing-device drivers/block/zram/zram_drv.h
--- a/drivers/block/zram/zram_drv.h~zram-add-free-space-management-in-backing-device
+++ a/drivers/block/zram/zram_drv.h
@@ -119,6 +119,9 @@ struct zram {
struct file *backing_dev;
struct block_device *bdev;
unsigned int old_block_size;
+ unsigned long *bitmap;
+ unsigned long nr_pages;
+ spinlock_t bitmap_lock;
#endif
};
#endif
_
Patches currently in -mm which might be from minchan@xxxxxxxxxx are
zram-clean-up-duplicated-codes-in-__zram_bvec_write.patch
zram-inlining-zram_compress.patch
zram-rename-zram_decompress_page-with-__zram_bvec_read.patch
zram-add-interface-to-specify-backing-device.patch
zram-add-free-space-management-in-backing-device.patch
zram-identify-asynchronous-ios-return-value.patch
zram-write-incompressible-pages-to-backing-device.patch
zram-read-page-from-backing-device.patch
zram-add-config-and-doc-file-for-writeback-feature.patch
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