LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>,
	Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>,
	linux-kernel@vger.kernel.org,
	Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Subject: [PATCHv2 2/7] zram: use idr instead of `zram_devices' array
Date: Sun,  1 Mar 2015 17:42:38 +0900	[thread overview]
Message-ID: <1425199363-15590-3-git-send-email-sergey.senozhatsky@gmail.com> (raw)
In-Reply-To: <1425199363-15590-1-git-send-email-sergey.senozhatsky@gmail.com>

This patch makes some preparations for dynamic device ADD/REMOVE functionality
via /dev/zram-control interface.

Remove `zram_devices' array and switch to id-to-pointer translation (idr).
idr doesn't bloat zram struct with additional members, f.e. list_head, yet
still provides ability to match the device_id with the device pointer.
No user-space visible changes.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
---
 drivers/block/zram/zram_drv.c | 81 ++++++++++++++++++++++++-------------------
 1 file changed, 46 insertions(+), 35 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 8fc2566..6707b7b 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -32,12 +32,12 @@
 #include <linux/string.h>
 #include <linux/vmalloc.h>
 #include <linux/err.h>
+#include <linux/idr.h>
 
 #include "zram_drv.h"
 
-/* Globals */
+static DEFINE_IDR(zram_index_idr);
 static int zram_major;
-static struct zram *zram_devices;
 static const char *default_compressor = "lzo";
 
 /* Module params (documentation at end) */
@@ -1061,18 +1061,28 @@ static struct attribute_group zram_disk_attr_group = {
 	.attrs = zram_disk_attrs,
 };
 
-static int create_device(struct zram *zram, int device_id)
+static int zram_add(int device_id)
 {
+	struct zram *zram;
 	struct request_queue *queue;
 	int ret = -ENOMEM;
 
+	zram = kzalloc(sizeof(struct zram), GFP_KERNEL);
+	if (!zram)
+		return ret;
+
+	ret = idr_alloc(&zram_index_idr, zram, device_id,
+			device_id + 1, GFP_KERNEL);
+	if (ret < 0)
+		goto out_free_dev;
+
 	init_rwsem(&zram->init_lock);
 
 	queue = blk_alloc_queue(GFP_KERNEL);
 	if (!queue) {
 		pr_err("Error allocating disk queue for device %d\n",
 			device_id);
-		goto out;
+		goto out_free_idr;
 	}
 
 	blk_queue_make_request(queue, zram_make_request);
@@ -1141,34 +1151,42 @@ out_free_disk:
 	put_disk(zram->disk);
 out_free_queue:
 	blk_cleanup_queue(queue);
-out:
+out_free_idr:
+	idr_remove(&zram_index_idr, device_id);
+out_free_dev:
+	kfree(zram);
 	return ret;
 }
 
-static void destroy_devices(unsigned int nr)
+static void zram_remove(struct zram *zram)
 {
-	struct zram *zram;
-	unsigned int i;
-
-	for (i = 0; i < nr; i++) {
-		zram = &zram_devices[i];
-		/*
-		 * Remove sysfs first, so no one will perform a disksize
-		 * store while we destroy the devices
-		 */
-		sysfs_remove_group(&disk_to_dev(zram->disk)->kobj,
-				&zram_disk_attr_group);
+	/*
+	 * Remove sysfs first, so no one will perform a disksize
+	 * store while we destroy the devices
+	 */
+	sysfs_remove_group(&disk_to_dev(zram->disk)->kobj,
+			&zram_disk_attr_group);
 
-		zram_reset_device(zram);
+	zram_reset_device(zram);
+	idr_remove(&zram_index_idr, zram->disk->first_minor);
+	blk_cleanup_queue(zram->disk->queue);
+	del_gendisk(zram->disk);
+	put_disk(zram->disk);
+	kfree(zram);
+}
 
-		blk_cleanup_queue(zram->disk->queue);
-		del_gendisk(zram->disk);
-		put_disk(zram->disk);
-	}
+static int zram_exit_cb(int id, void *ptr, void *data)
+{
+	zram_remove(ptr);
+	return 0;
+}
 
-	kfree(zram_devices);
+static void destroy_devices(void)
+{
+	idr_for_each(&zram_index_idr, &zram_exit_cb, NULL);
+	idr_destroy(&zram_index_idr);
 	unregister_blkdev(zram_major, "zram");
-	pr_info("Destroyed %u device(s)\n", nr);
+	pr_info("Destroyed device(s)\n");
 }
 
 static int __init zram_init(void)
@@ -1187,16 +1205,9 @@ static int __init zram_init(void)
 		return -EBUSY;
 	}
 
-	/* Allocate the device array and initialize each one */
-	zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
-	if (!zram_devices) {
-		unregister_blkdev(zram_major, "zram");
-		return -ENOMEM;
-	}
-
 	for (dev_id = 0; dev_id < num_devices; dev_id++) {
-		ret = create_device(&zram_devices[dev_id], dev_id);
-		if (ret)
+		ret = zram_add(dev_id);
+		if (ret != 0)
 			goto out_error;
 	}
 
@@ -1204,13 +1215,13 @@ static int __init zram_init(void)
 	return 0;
 
 out_error:
-	destroy_devices(dev_id);
+	destroy_devices();
 	return ret;
 }
 
 static void __exit zram_exit(void)
 {
-	destroy_devices(num_devices);
+	destroy_devices();
 }
 
 module_init(zram_init);
-- 
2.3.1.167.g7f4ba4b


  parent reply	other threads:[~2015-03-01  8:42 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-01  8:42 [PATCHv2 0/7] introduce dynamic device creation/removal Sergey Senozhatsky
2015-03-01  8:42 ` [PATCHv2 1/7] zram: cosmetic ZRAM_ATTR_RO code formatting tweak Sergey Senozhatsky
2015-03-01  8:42 ` Sergey Senozhatsky [this message]
2015-03-01  8:42 ` [PATCHv2 3/7] zram: factor out device reset from reset_store() Sergey Senozhatsky
2015-03-01  8:42 ` [PATCHv2 4/7] zram: reorganize code layout Sergey Senozhatsky
2015-03-01  8:42 ` [PATCHv2 5/7] zram: add dynamic device add/remove functionality Sergey Senozhatsky
2015-03-01  8:42 ` [PATCHv2 6/7] zram: remove max_num_devices limitation Sergey Senozhatsky
2015-03-01  8:42 ` [PATCHv2 7/7] zram: report every added and removed device Sergey Senozhatsky
2015-03-03  6:51 ` [PATCHv2 0/7] introduce dynamic device creation/removal Sergey Senozhatsky

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1425199363-15590-3-git-send-email-sergey.senozhatsky@gmail.com \
    --to=sergey.senozhatsky@gmail.com \
    --cc=akpm@linux-foundation.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=minchan@kernel.org \
    --cc=ngupta@vflare.org \
    --cc=sergey.senozhatsky.work@gmail.com \
    --subject='Re: [PATCHv2 2/7] zram: use idr instead of `zram_devices'\'' array' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).