4 files changed, 66 insertions, 10 deletions

diff --git a/fs/squashfs/Kconfig b/fs/squashfs/Kconfig
index 218bacdd4298..60fc98bdf421 100644
--- a/fs/squashfs/Kconfig
+++ b/fs/squashfs/Kconfig
@@ -73,11 +73,10 @@ config SQUASHFS_CHOICE_DECOMP_BY_MOUNT
 	select SQUASHFS_DECOMP_SINGLE
 	select SQUASHFS_DECOMP_MULTI
 	select SQUASHFS_DECOMP_MULTI_PERCPU
+	select SQUASHFS_MOUNT_DECOMP_THREADS
 	help
 	  Compile all parallel decompression modes and specify the
 	  decompression mode by setting "threads=" during mount.
-	    threads=<single|multi|percpu>
-
 	  default Decompressor parallelisation is SQUASHFS_DECOMP_SINGLE
 
 choice
@@ -127,6 +126,19 @@ config SQUASHFS_COMPILE_DECOMP_MULTI_PERCPU
 	  decompression is load-balanced across the cores.
 endchoice
 
+config SQUASHFS_MOUNT_DECOMP_THREADS
+	bool "Add the mount parameter 'threads=' for squashfs"
+	depends on SQUASHFS
+	depends on SQUASHFS_DECOMP_MULTI
+	default n
+	help
+	  Use threads= to set the decompression parallel mode and the number of threads.
+	  If SQUASHFS_CHOICE_DECOMP_BY_MOUNT=y
+	      threads=<single|multi|percpu|1|2|3|...>
+	  else
+	      threads=<2|3|...>
+	  The upper limit is num_online_cpus() * 2.
+
 config SQUASHFS_XATTR
 	bool "Squashfs XATTR support"
 	depends on SQUASHFS
diff --git a/fs/squashfs/decompressor_multi.c b/fs/squashfs/decompressor_multi.c
index eb25432bd149..416c53eedbd1 100644
--- a/fs/squashfs/decompressor_multi.c
+++ b/fs/squashfs/decompressor_multi.c
@@ -144,7 +144,7 @@ static struct decomp_stream *get_decomp_stream(struct squashfs_sb_info *msblk,
 		 * If there is no available decomp and already full,
 		 * let's wait for releasing decomp from other users.
 		 */
-		if (stream->avail_decomp >= MAX_DECOMPRESSOR)
+		if (stream->avail_decomp >= msblk->max_thread_num)
 			goto wait;
 
 		/* Let's allocate new decomp */
@@ -160,7 +160,7 @@ static struct decomp_stream *get_decomp_stream(struct squashfs_sb_info *msblk,
 		}
 
 		stream->avail_decomp++;
-		WARN_ON(stream->avail_decomp > MAX_DECOMPRESSOR);
+		WARN_ON(stream->avail_decomp > msblk->max_thread_num);
 
 		mutex_unlock(&stream->mutex);
 		break;
diff --git a/fs/squashfs/squashfs_fs_sb.h b/fs/squashfs/squashfs_fs_sb.h
index f1e5dad8ae0a..659082e9e51d 100644
--- a/fs/squashfs/squashfs_fs_sb.h
+++ b/fs/squashfs/squashfs_fs_sb.h
@@ -67,5 +67,6 @@ struct squashfs_sb_info {
 	unsigned int				ids;
 	bool					panic_on_errors;
 	const struct squashfs_decompressor_thread_ops *thread_ops;
+	int					max_thread_num;
 };
 #endif
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;