[PATCH v6 2/2] squashfs: Allows users to configure the number of decompression threads

From: Xiaoming Ni
Date: Tue Oct 18 2022 - 23:06:26 EST


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.

Signed-off-by: Xiaoming Ni <nixiaoming@xxxxxxxxxx>
---
fs/squashfs/Kconfig | 16 ++++++++--
fs/squashfs/decompressor_multi.c | 4 +--
fs/squashfs/squashfs_fs_sb.h | 1 +
fs/squashfs/super.c | 55 ++++++++++++++++++++++++++++----
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;
@@ -467,14 +510,13 @@ 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;
--
2.27.0