fs/squashfs/lz4_wrapper.c

Source file repositories/reference/linux-study-clean/fs/squashfs/lz4_wrapper.c

File Facts

System
Linux kernel
Corpus path
fs/squashfs/lz4_wrapper.c
Extension
.c
Size
3006 bytes
Lines
147
Domain
Core OS
Bucket
VFS And Filesystem Core
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

struct lz4_comp_opts {
	__le32 version;
	__le32 flags;
};

struct squashfs_lz4 {
	void *input;
	void *output;
};


static void *lz4_comp_opts(struct squashfs_sb_info *msblk,
	void *buff, int len)
{
	struct lz4_comp_opts *comp_opts = buff;

	/* LZ4 compressed filesystems always have compression options */
	if (comp_opts == NULL || len < sizeof(*comp_opts))
		return ERR_PTR(-EIO);

	if (le32_to_cpu(comp_opts->version) != LZ4_LEGACY) {
		/* LZ4 format currently used by the kernel is the 'legacy'
		 * format */
		ERROR("Unknown LZ4 version\n");
		return ERR_PTR(-EINVAL);
	}

	return NULL;
}


static void *lz4_init(struct squashfs_sb_info *msblk, void *buff)
{
	int block_size = max_t(int, msblk->block_size, SQUASHFS_METADATA_SIZE);
	struct squashfs_lz4 *stream;

	stream = kzalloc_obj(*stream);
	if (stream == NULL)
		goto failed;
	stream->input = vmalloc(block_size);
	if (stream->input == NULL)
		goto failed2;
	stream->output = vmalloc(block_size);
	if (stream->output == NULL)
		goto failed3;

	return stream;

failed3:
	vfree(stream->input);
failed2:
	kfree(stream);
failed:
	ERROR("Failed to initialise LZ4 decompressor\n");
	return ERR_PTR(-ENOMEM);
}


static void lz4_free(void *strm)
{
	struct squashfs_lz4 *stream = strm;

	if (stream) {
		vfree(stream->input);
		vfree(stream->output);
	}
	kfree(stream);
}


static int lz4_uncompress(struct squashfs_sb_info *msblk, void *strm,
	struct bio *bio, int offset, int length,
	struct squashfs_page_actor *output)
{
	struct bvec_iter_all iter_all = {};
	struct bio_vec *bvec = bvec_init_iter_all(&iter_all);
	struct squashfs_lz4 *stream = strm;
	void *buff = stream->input, *data;
	int bytes = length, res;

	while (bio_next_segment(bio, &iter_all)) {
		int avail = min(bytes, ((int)bvec->bv_len) - offset);

		data = bvec_virt(bvec);
		memcpy(buff, data + offset, avail);
		buff += avail;
		bytes -= avail;
		offset = 0;
	}

Annotation

Implementation Notes