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zram: add interface to specif backing device

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For writeback feature, user should set up backing device before the zram
working.

This patch enables the interface via /sys/block/zramX/backing_dev.

Currently, it supports block device only but it could be enhanced for
file as well.

Link: http://lkml.kernel.org/r/1498459987-24562-5-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Juneho Choi <juno.choi@lge.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Minchan Kim 2017-09-06 16:19:54 -07:00 committed by Linus Torvalds
parent 693dc1ce25
commit 013bf95a83
2 changed files with 147 additions and 0 deletions
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142
drivers/block/zram/zram_drv.c
View File

@ -270,6 +270,141 @@ static ssize_t mem_used_max_store(struct device *dev,
return len;
}
#ifdef CONFIG_ZRAM_WRITEBACK
static bool zram_wb_enabled(struct zram *zram)
{
return zram->backing_dev;
}
static void reset_bdev(struct zram *zram)
{
struct block_device *bdev;
if (!zram_wb_enabled(zram))
return;
bdev = zram->bdev;
if (zram->old_block_size)
set_blocksize(bdev, zram->old_block_size);
blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
/* hope filp_close flush all of IO */
filp_close(zram->backing_dev, NULL);
zram->backing_dev = NULL;
zram->old_block_size = 0;
zram->bdev = NULL;
}
static ssize_t backing_dev_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct zram *zram = dev_to_zram(dev);
struct file *file = zram->backing_dev;
char *p;
ssize_t ret;
down_read(&zram->init_lock);
if (!zram_wb_enabled(zram)) {
memcpy(buf, "none\n", 5);
up_read(&zram->init_lock);
return 5;
}
p = file_path(file, buf, PAGE_SIZE - 1);
if (IS_ERR(p)) {
ret = PTR_ERR(p);
goto out;
}
ret = strlen(p);
memmove(buf, p, ret);
buf[ret++] = '\n';
out:
up_read(&zram->init_lock);
return ret;
}
static ssize_t backing_dev_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t len)
{
char *file_name;
struct file *backing_dev = NULL;
struct inode *inode;
struct address_space *mapping;
unsigned int old_block_size = 0;
struct block_device *bdev = NULL;
int err;
struct zram *zram = dev_to_zram(dev);
file_name = kmalloc(PATH_MAX, GFP_KERNEL);
if (!file_name)
return -ENOMEM;
down_write(&zram->init_lock);
if (init_done(zram)) {
pr_info("Can't setup backing device for initialized device\n");
err = -EBUSY;
goto out;
}
strlcpy(file_name, buf, len);
backing_dev = filp_open(file_name, O_RDWR|O_LARGEFILE, 0);
if (IS_ERR(backing_dev)) {
err = PTR_ERR(backing_dev);
backing_dev = NULL;
goto out;
}
mapping = backing_dev->f_mapping;
inode = mapping->host;
/* Support only block device in this moment */
if (!S_ISBLK(inode->i_mode)) {
err = -ENOTBLK;
goto out;
}
bdev = bdgrab(I_BDEV(inode));
err = blkdev_get(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL, zram);
if (err < 0)
goto out;
old_block_size = block_size(bdev);
err = set_blocksize(bdev, PAGE_SIZE);
if (err)
goto out;
reset_bdev(zram);
zram->old_block_size = old_block_size;
zram->bdev = bdev;
zram->backing_dev = backing_dev;
up_write(&zram->init_lock);
pr_info("setup backing device %s\n", file_name);
kfree(file_name);
return len;
out:
if (bdev)
blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
if (backing_dev)
filp_close(backing_dev, NULL);
up_write(&zram->init_lock);
kfree(file_name);
return err;
}
#else
static bool zram_wb_enabled(struct zram *zram) { return false; }
static inline void reset_bdev(struct zram *zram) {};
#endif
/*
* We switched to per-cpu streams and this attr is not needed anymore.
* However, we will keep it around for some time, because:
@ -953,6 +1088,7 @@ static void zram_reset_device(struct zram *zram)
zram_meta_free(zram, disksize);
memset(&zram->stats, 0, sizeof(zram->stats));
zcomp_destroy(comp);
reset_bdev(zram);
}
static ssize_t disksize_store(struct device *dev,
@ -1078,6 +1214,9 @@ static DEVICE_ATTR_WO(mem_limit);
static DEVICE_ATTR_WO(mem_used_max);
static DEVICE_ATTR_RW(max_comp_streams);
static DEVICE_ATTR_RW(comp_algorithm);
#ifdef CONFIG_ZRAM_WRITEBACK
static DEVICE_ATTR_RW(backing_dev);
#endif
static struct attribute *zram_disk_attrs[] = {
&dev_attr_disksize.attr,
@ -1088,6 +1227,9 @@ static struct attribute *zram_disk_attrs[] = {
&dev_attr_mem_used_max.attr,
&dev_attr_max_comp_streams.attr,
&dev_attr_comp_algorithm.attr,
#ifdef CONFIG_ZRAM_WRITEBACK
&dev_attr_backing_dev.attr,
#endif
&dev_attr_io_stat.attr,
&dev_attr_mm_stat.attr,
&dev_attr_debug_stat.attr,

5
drivers/block/zram/zram_drv.h
View File

@ -115,5 +115,10 @@ struct zram {
* zram is claimed so open request will be failed
*/
bool claim; /* Protected by bdev->bd_mutex */
#ifdef CONFIG_ZRAM_WRITEBACK
struct file *backing_dev;
struct block_device *bdev;
unsigned int old_block_size;
#endif
};
#endif