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zram: add interface to specif backing device
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>
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@ -270,6 +270,141 @@ static ssize_t mem_used_max_store(struct device *dev,
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return len;
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}
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#ifdef CONFIG_ZRAM_WRITEBACK
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static bool zram_wb_enabled(struct zram *zram)
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{
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return zram->backing_dev;
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}
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static void reset_bdev(struct zram *zram)
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{
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struct block_device *bdev;
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if (!zram_wb_enabled(zram))
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return;
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bdev = zram->bdev;
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if (zram->old_block_size)
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set_blocksize(bdev, zram->old_block_size);
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blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
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/* hope filp_close flush all of IO */
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filp_close(zram->backing_dev, NULL);
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zram->backing_dev = NULL;
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zram->old_block_size = 0;
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zram->bdev = NULL;
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}
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static ssize_t backing_dev_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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struct zram *zram = dev_to_zram(dev);
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struct file *file = zram->backing_dev;
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char *p;
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ssize_t ret;
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down_read(&zram->init_lock);
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if (!zram_wb_enabled(zram)) {
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memcpy(buf, "none\n", 5);
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up_read(&zram->init_lock);
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return 5;
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}
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p = file_path(file, buf, PAGE_SIZE - 1);
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if (IS_ERR(p)) {
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ret = PTR_ERR(p);
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goto out;
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}
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ret = strlen(p);
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memmove(buf, p, ret);
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buf[ret++] = '\n';
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out:
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up_read(&zram->init_lock);
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return ret;
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}
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static ssize_t backing_dev_store(struct device *dev,
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struct device_attribute *attr, const char *buf, size_t len)
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{
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char *file_name;
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struct file *backing_dev = NULL;
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struct inode *inode;
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struct address_space *mapping;
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unsigned int old_block_size = 0;
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struct block_device *bdev = NULL;
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int err;
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struct zram *zram = dev_to_zram(dev);
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file_name = kmalloc(PATH_MAX, GFP_KERNEL);
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if (!file_name)
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return -ENOMEM;
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down_write(&zram->init_lock);
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if (init_done(zram)) {
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pr_info("Can't setup backing device for initialized device\n");
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err = -EBUSY;
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goto out;
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}
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strlcpy(file_name, buf, len);
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backing_dev = filp_open(file_name, O_RDWR|O_LARGEFILE, 0);
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if (IS_ERR(backing_dev)) {
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err = PTR_ERR(backing_dev);
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backing_dev = NULL;
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goto out;
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}
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mapping = backing_dev->f_mapping;
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inode = mapping->host;
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/* Support only block device in this moment */
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if (!S_ISBLK(inode->i_mode)) {
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err = -ENOTBLK;
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goto out;
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}
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bdev = bdgrab(I_BDEV(inode));
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err = blkdev_get(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL, zram);
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if (err < 0)
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goto out;
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old_block_size = block_size(bdev);
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err = set_blocksize(bdev, PAGE_SIZE);
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if (err)
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goto out;
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reset_bdev(zram);
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zram->old_block_size = old_block_size;
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zram->bdev = bdev;
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zram->backing_dev = backing_dev;
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up_write(&zram->init_lock);
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pr_info("setup backing device %s\n", file_name);
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kfree(file_name);
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return len;
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out:
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if (bdev)
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blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
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if (backing_dev)
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filp_close(backing_dev, NULL);
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up_write(&zram->init_lock);
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kfree(file_name);
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return err;
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}
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#else
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static bool zram_wb_enabled(struct zram *zram) { return false; }
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static inline void reset_bdev(struct zram *zram) {};
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#endif
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/*
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* We switched to per-cpu streams and this attr is not needed anymore.
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* However, we will keep it around for some time, because:
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@ -953,6 +1088,7 @@ static void zram_reset_device(struct zram *zram)
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zram_meta_free(zram, disksize);
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memset(&zram->stats, 0, sizeof(zram->stats));
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zcomp_destroy(comp);
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reset_bdev(zram);
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}
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static ssize_t disksize_store(struct device *dev,
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@ -1078,6 +1214,9 @@ static DEVICE_ATTR_WO(mem_limit);
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static DEVICE_ATTR_WO(mem_used_max);
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static DEVICE_ATTR_RW(max_comp_streams);
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static DEVICE_ATTR_RW(comp_algorithm);
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#ifdef CONFIG_ZRAM_WRITEBACK
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static DEVICE_ATTR_RW(backing_dev);
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#endif
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static struct attribute *zram_disk_attrs[] = {
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&dev_attr_disksize.attr,
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@ -1088,6 +1227,9 @@ static struct attribute *zram_disk_attrs[] = {
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&dev_attr_mem_used_max.attr,
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&dev_attr_max_comp_streams.attr,
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&dev_attr_comp_algorithm.attr,
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#ifdef CONFIG_ZRAM_WRITEBACK
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&dev_attr_backing_dev.attr,
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#endif
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&dev_attr_io_stat.attr,
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&dev_attr_mm_stat.attr,
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&dev_attr_debug_stat.attr,
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@ -115,5 +115,10 @@ struct zram {
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* zram is claimed so open request will be failed
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*/
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bool claim; /* Protected by bdev->bd_mutex */
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#ifdef CONFIG_ZRAM_WRITEBACK
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struct file *backing_dev;
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struct block_device *bdev;
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unsigned int old_block_size;
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#endif
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};
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#endif
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