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Subject[PATCH 4.19 10/39] Revert "zram: close udev startup race condition as default groups"
Date
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

From: Jeffle Xu <jefflexu@linux.alibaba.com>

This reverts commit 9e07f4e243791e00a4086ad86e573705cf7b2c65.

The original commit is actually a "merged" fix of [1] and [2], as
described in [3]. Since now we have more fixes that rely on [1], revert
this commit first, and then get the original [1] and [2] merged.

[1] fef912bf860e, block: genhd: add 'groups' argument to device_add_disk
[2] 98af4d4df889, zram: register default groups with device_add_disk()
[3] https://www.spinics.net/lists/stable/msg442196.html

Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/block/zram/zram_drv.c | 26 ++++++++++++++++++++------
1 file changed, 20 insertions(+), 6 deletions(-)

--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1644,11 +1644,6 @@ static const struct attribute_group zram
.attrs = zram_disk_attrs,
};

-static const struct attribute_group *zram_disk_attr_groups[] = {
- &zram_disk_attr_group,
- NULL,
-};
-
/*
* Allocate and initialize new zram device. the function returns
* '>= 0' device_id upon success, and negative value otherwise.
@@ -1729,15 +1724,24 @@ static int zram_add(void)

zram->disk->queue->backing_dev_info->capabilities |=
(BDI_CAP_STABLE_WRITES | BDI_CAP_SYNCHRONOUS_IO);
- disk_to_dev(zram->disk)->groups = zram_disk_attr_groups;
add_disk(zram->disk);

+ ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj,
+ &zram_disk_attr_group);
+ if (ret < 0) {
+ pr_err("Error creating sysfs group for device %d\n",
+ device_id);
+ goto out_free_disk;
+ }
strlcpy(zram->compressor, default_compressor, sizeof(zram->compressor));

zram_debugfs_register(zram);
pr_info("Added device: %s\n", zram->disk->disk_name);
return device_id;

+out_free_disk:
+ del_gendisk(zram->disk);
+ put_disk(zram->disk);
out_free_queue:
blk_cleanup_queue(queue);
out_free_idr:
@@ -1766,6 +1770,16 @@ static int zram_remove(struct zram *zram
mutex_unlock(&bdev->bd_mutex);

zram_debugfs_unregister(zram);
+ /*
+ * Remove sysfs first, so no one will perform a disksize
+ * store while we destroy the devices. This also helps during
+ * hot_remove -- zram_reset_device() is the last holder of
+ * ->init_lock, no later/concurrent disksize_store() or any
+ * other sysfs handlers are possible.
+ */
+ sysfs_remove_group(&disk_to_dev(zram->disk)->kobj,
+ &zram_disk_attr_group);
+
/* Make sure all the pending I/O are finished */
fsync_bdev(bdev);
zram_reset_device(zram);

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