linux-kernel - [PATCH 02/10] dax: reduce stack footprint dealing with block device names

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Date:   Wed,  2 Jun 2021 18:28:55 +0300
From:   Anton Suvorov <warwish@...dex-team.ru>
To:     linux-kernel@...r.kernel.org
Cc:     warwish@...dex-team.ru, linux-fsdevel@...r.kernel.org,
        dmtrmonakhov@...dex-team.ru, linux-block@...r.kernel.org,
        viro@...iv.linux.org.uk
Subject: [PATCH 02/10] dax: reduce stack footprint dealing with block device names

Stack usage reduced (measured with allyesconfig):

./drivers/dax/super.c   __bdev_dax_supported    192     56      -136
./drivers/dax/super.c   __generic_fsdax_supported       344     280     -64

Signed-off-by: Anton Suvorov <warwish@...dex-team.ru>
---
 drivers/dax/super.c | 34 ++++++++++++++++------------------
 1 file changed, 16 insertions(+), 18 deletions(-)

diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index 5fa6ae9dbc8b..f694e25fe6af 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -73,7 +73,6 @@ bool __generic_fsdax_supported(struct dax_device *dax_dev,
 {
 	bool dax_enabled = false;
 	pgoff_t pgoff, pgoff_end;
-	char buf[BDEVNAME_SIZE];
 	void *kaddr, *end_kaddr;
 	pfn_t pfn, end_pfn;
 	sector_t last_page;
@@ -81,29 +80,29 @@ bool __generic_fsdax_supported(struct dax_device *dax_dev,
 	int err, id;
 
 	if (blocksize != PAGE_SIZE) {
-		pr_info("%s: error: unsupported blocksize for dax\n",
-				bdevname(bdev, buf));
+		pr_info("%pg: error: unsupported blocksize for dax\n",
+			bdev);
 		return false;
 	}
 
 	if (!dax_dev) {
-		pr_debug("%s: error: dax unsupported by block device\n",
-				bdevname(bdev, buf));
+		pr_debug("%pg: error: dax unsupported by block device\n",
+			 bdev);
 		return false;
 	}
 
 	err = bdev_dax_pgoff(bdev, start, PAGE_SIZE, &pgoff);
 	if (err) {
-		pr_info("%s: error: unaligned partition for dax\n",
-				bdevname(bdev, buf));
+		pr_info("%pg: error: unaligned partition for dax\n",
+			bdev);
 		return false;
 	}
 
 	last_page = PFN_DOWN((start + sectors - 1) * 512) * PAGE_SIZE / 512;
 	err = bdev_dax_pgoff(bdev, last_page, PAGE_SIZE, &pgoff_end);
 	if (err) {
-		pr_info("%s: error: unaligned partition for dax\n",
-				bdevname(bdev, buf));
+		pr_info("%pg: error: unaligned partition for dax\n",
+			bdev);
 		return false;
 	}
 
@@ -112,8 +111,8 @@ bool __generic_fsdax_supported(struct dax_device *dax_dev,
 	len2 = dax_direct_access(dax_dev, pgoff_end, 1, &end_kaddr, &end_pfn);
 
 	if (len < 1 || len2 < 1) {
-		pr_info("%s: error: dax access failed (%ld)\n",
-				bdevname(bdev, buf), len < 1 ? len : len2);
+		pr_info("%pg: error: dax access failed (%ld)\n",
+			bdev, len < 1 ? len : len2);
 		dax_read_unlock(id);
 		return false;
 	}
@@ -147,8 +146,8 @@ bool __generic_fsdax_supported(struct dax_device *dax_dev,
 	dax_read_unlock(id);
 
 	if (!dax_enabled) {
-		pr_info("%s: error: dax support not enabled\n",
-				bdevname(bdev, buf));
+		pr_info("%pg: error: dax support not enabled\n",
+			bdev);
 		return false;
 	}
 	return true;
@@ -169,21 +168,20 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
 {
 	struct dax_device *dax_dev;
 	struct request_queue *q;
-	char buf[BDEVNAME_SIZE];
 	bool ret;
 	int id;
 
 	q = bdev_get_queue(bdev);
 	if (!q || !blk_queue_dax(q)) {
-		pr_debug("%s: error: request queue doesn't support dax\n",
-				bdevname(bdev, buf));
+		pr_debug("%pg: error: request queue doesn't support dax\n",
+			 bdev);
 		return false;
 	}
 
 	dax_dev = dax_get_by_host(bdev->bd_disk->disk_name);
 	if (!dax_dev) {
-		pr_debug("%s: error: device does not support dax\n",
-				bdevname(bdev, buf));
+		pr_debug("%pg: error: device does not support dax\n",
+			 bdev);
 		return false;
 	}
 
-- 
2.25.1