linux-kernel - [PATCH 1/2] Squashfs: Let the number of fragments cached configurable

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Message-ID: <1508370660-6343-2-git-send-email-wuqixuan@huawei.com>
Date:   Thu, 19 Oct 2017 07:50:59 +0800
From:   Qixuan Wu <wuqixuan@...wei.com>
To:     <phillip@...ashfs.org.uk>, <corbet@....net>
CC:     <paulmck@...ux.vnet.ibm.com>, <akpm@...ux-foundation.org>,
        <tglx@...utronix.de>, <cdall@...aro.org>, <mingo@...nel.org>,
        <marc.zyngier@....com>, <mchehab@...nel.org>,
        <zohar@...ux.vnet.ibm.com>, <linux-doc@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <squashfs-devel@...ts.sourceforge.net>, <wuqixuan@...wei.com>,
        Chen Jie <chenjie6@...wei.com>
Subject: [PATCH 1/2] Squashfs: Let the number of fragments cached configurable

Currently, squashfs fragments' cache size is only determined by
config option CONFIG_SQUASHFS_FRAGMENT_CACHE_SIZE. Users have
no way to change the value when they get the binary kernel.
Now make it be configured during booting or inserting module.

Signed-off-by: Qixuan Wu <wuqixuan@...wei.com>
Signed-off-by: Chen Jie <chenjie6@...wei.com>
---
 fs/squashfs/super.c | 43 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 42 insertions(+), 1 deletion(-)

diff --git a/fs/squashfs/super.c b/fs/squashfs/super.c
index cf01e15..82f9e46 100644
--- a/fs/squashfs/super.c
+++ b/fs/squashfs/super.c
@@ -38,6 +38,7 @@
 #include <linux/module.h>
 #include <linux/magic.h>
 #include <linux/xattr.h>
+#include <linux/ctype.h>
 
 #include "squashfs_fs.h"
 #include "squashfs_fs_sb.h"
@@ -49,6 +50,37 @@
 static struct file_system_type squashfs_fs_type;
 static const struct super_operations squashfs_super_ops;
 
+static unsigned int squashfs_frags_cache_size = SQUASHFS_CACHED_FRAGMENTS;
+
+#ifndef	MODULE
+static int __init squashfs_frags_cachesize_setup(char *buf)
+{
+	unsigned int arg;
+
+	if (!buf || kstrtouint(buf, 10, &arg) < 0) {
+		pr_err("Bad squashfs fragments' cache size, let it be %d\n",
+			SQUASHFS_CACHED_FRAGMENTS);
+		return 0;
+	}
+
+	if (arg < 3 || arg > 99) {
+		pr_warn("Squashfs fragments' cache size should be in the range "
+			"of [3,99]. Let it be %d\n", SQUASHFS_CACHED_FRAGMENTS);
+		return 0;
+	}
+
+	squashfs_frags_cache_size = arg;
+
+	return 0;
+}
+early_param("squashfs.frags_cache_size", squashfs_frags_cachesize_setup);
+
+#else
+module_param(squashfs_frags_cache_size, uint, 0444);
+MODULE_PARM_DESC(squashfs_frags_cache_size,
+	"Squashfs fragments' cache size, it should be in the range of [3,99]");
+#endif
+
 static const struct squashfs_decompressor *supported_squashfs_filesystem(short
 	major, short minor, short id)
 {
@@ -276,8 +308,17 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
 	if (fragments == 0)
 		goto check_directory_table;
 
+	if ((squashfs_frags_cache_size < 3)
+		|| (squashfs_frags_cache_size > 99)) {
+		ERROR("Fragments' cache size should be in the range of[3,99]."
+			"Let it be %d\n", SQUASHFS_CACHED_FRAGMENTS);
+		squashfs_frags_cache_size = SQUASHFS_CACHED_FRAGMENTS;
+	}
+
+	TRACE("Fragments' cache size %d\n", squashfs_frags_cache_size);
+
 	msblk->fragment_cache = squashfs_cache_init("fragment",
-		SQUASHFS_CACHED_FRAGMENTS, msblk->block_size);
+		squashfs_frags_cache_size, msblk->block_size);
 	if (msblk->fragment_cache == NULL) {
 		err = -ENOMEM;
 		goto failed_mount;
-- 
2.7.4