squashfs: allows users to configure the number of decompression threads

The maximum number of threads in the decompressor_multi.c file is fixed
and cannot be adjusted according to user needs.  Therefore, the mount
parameter needs to be added to allow users to configure the number of
threads as required.  The upper limit is num_online_cpus() * 2.

Link: https://lkml.kernel.org/r/20221019030930.130456-3-nixiaoming@huawei.com
Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com>
Reviewed-by: Phillip Lougher <phillip@squashfs.org.uk>
Cc: Jianguo Chen <chenjianguo3@huawei.com>
Cc: Jubin Zhong <zhongjubin@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 49 insertions, 6 deletions

diff --git a/fs/squashfs/super.c b/fs/squashfs/super.c
index aac3ea72a9ba..1e428ca9414e 100644
--- a/fs/squashfs/super.c
+++ b/fs/squashfs/super.c
@@ -53,6 +53,7 @@ enum squashfs_param {
 struct squashfs_mount_opts {
 	enum Opt_errors errors;
 	const struct squashfs_decompressor_thread_ops *thread_ops;
+	int thread_num;
 };
 
 static const struct constant_table squashfs_param_errors[] = {
@@ -67,7 +68,8 @@ static const struct fs_parameter_spec squashfs_fs_parameters[] = {
 	{}
 };
 
-static int squashfs_parse_param_threads(const char *str, struct squashfs_mount_opts *opts)
+
+static int squashfs_parse_param_threads_str(const char *str, struct squashfs_mount_opts *opts)
 {
 #ifdef CONFIG_SQUASHFS_CHOICE_DECOMP_BY_MOUNT
 	if (strcmp(str, "single") == 0) {
@@ -86,6 +88,42 @@ static int squashfs_parse_param_threads(const char *str, struct squashfs_mount_o
 	return -EINVAL;
 }
 
+static int squashfs_parse_param_threads_num(const char *str, struct squashfs_mount_opts *opts)
+{
+#ifdef CONFIG_SQUASHFS_MOUNT_DECOMP_THREADS
+	int ret;
+	unsigned long num;
+
+	ret = kstrtoul(str, 0, &num);
+	if (ret != 0)
+		return -EINVAL;
+	if (num > 1) {
+		opts->thread_ops = &squashfs_decompressor_multi;
+		if (num > opts->thread_ops->max_decompressors())
+			return -EINVAL;
+		opts->thread_num = (int)num;
+		return 0;
+	}
+#ifdef CONFIG_SQUASHFS_DECOMP_SINGLE
+	if (num == 1) {
+		opts->thread_ops = &squashfs_decompressor_single;
+		opts->thread_num = 1;
+		return 0;
+	}
+#endif
+#endif /* !CONFIG_SQUASHFS_MOUNT_DECOMP_THREADS */
+	return -EINVAL;
+}
+
+static int squashfs_parse_param_threads(const char *str, struct squashfs_mount_opts *opts)
+{
+	int ret = squashfs_parse_param_threads_str(str, opts);
+
+	if (ret == 0)
+		return ret;
+	return squashfs_parse_param_threads_num(str, opts);
+}
+
 static int squashfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
 {
 	struct squashfs_mount_opts *opts = fc->fs_private;
@@ -194,6 +232,11 @@ static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc)
 		goto failed_mount;
 	}
 	msblk->thread_ops = opts->thread_ops;
+	if (opts->thread_num == 0) {
+		msblk->max_thread_num = msblk->thread_ops->max_decompressors();
+	} else {
+		msblk->max_thread_num = opts->thread_num;
+	}
 
 	/* Check the MAJOR & MINOR versions and lookup compression type */
 	msblk->decompressor = supported_squashfs_filesystem(
@@ -279,7 +322,7 @@ static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc)
 
 	/* Allocate read_page block */
 	msblk->read_page = squashfs_cache_init("data",
-		msblk->thread_ops->max_decompressors(), msblk->block_size);
+		msblk->max_thread_num, msblk->block_size);
 	if (msblk->read_page == NULL) {
 		errorf(fc, "Failed to allocate read_page block");
 		goto failed_mount;
@@ -467,15 +510,14 @@ static int squashfs_show_options(struct seq_file *s, struct dentry *root)
 		seq_puts(s, ",threads=single");
 		return 0;
 	}
-	if (msblk->thread_ops == &squashfs_decompressor_multi) {
-		seq_puts(s, ",threads=multi");
-		return 0;
-	}
 	if (msblk->thread_ops == &squashfs_decompressor_percpu) {
 		seq_puts(s, ",threads=percpu");
 		return 0;
 	}
 #endif
+#ifdef CONFIG_SQUASHFS_MOUNT_DECOMP_THREADS
+	seq_printf(s, ",threads=%d", msblk->max_thread_num);
+#endif
 	return 0;
 }
 
@@ -496,6 +538,7 @@ static int squashfs_init_fs_context(struct fs_context *fc)
 #else
 #error "fail: unknown squashfs decompression thread mode?"
 #endif
+	opts->thread_num = 0;
 	fc->fs_private = opts;
 	fc->ops = &squashfs_context_ops;
 	return 0;