On Wed, 20 Aug 2008, Jared Hulbert wrote:
> Handles the decompression for axfs, modeled after fs/cramfs/uncompress.c.
>
> Signed-off-by: Jared Hulbert <jaredeh@xxxxxxxxx>
> ---
> diff --git a/fs/axfs/axfs_uncompress.c b/fs/axfs/axfs_uncompress.c
> new file mode 100644
> index 0000000..b7a2060
> --- /dev/null
> +++ b/fs/axfs/axfs_uncompress.c
> @@ -0,0 +1,97 @@
> +/*
> + * Advanced XIP File System for Linux - AXFS
> + * Readonly, compressed, and XIP filesystem for Linux systems big and small
> + *
> + * Modified in 2006 by Eric Anderson
> + * from the cramfs sources fs/cramfs/uncompress.c
> + *
> + * (C) Copyright 1999 Linus Torvalds
> + *
> + * axfs_uncompress.c -
> + * axfs interfaces to the uncompression library. There's really just
> + * three entrypoints:
> + *
> + * - axfs_uncompress_init() - called to initialize the thing.
> + * - axfs_uncompress_exit() - tell me when you're done
> + * - axfs_uncompress_block() - uncompress a block.
> + *
> + * NOTE NOTE NOTE! The uncompression is entirely single-threaded. We
> + * only have one stream, and we'll initialize it only once even if it
> + * then is used by multiple filesystems.
> + *
> + */
> +
> +#include <linux/errno.h>
> +#include <linux/vmalloc.h>
> +#include <linux/zlib.h>
> +#include <linux/mutex.h>
> +
> +static z_stream stream;
> +static int initialized;
> +static struct mutex axfs_uncmp_mutex;
Use DEFINE_MUTEX and drop the mutex_init() down in the init function.
> +
> +int axfs_uncompress_block(void *dst, int dstlen, void *src, int srclen)
> +{
> + int err;
> + int out;
> +
> + mutex_lock(&axfs_uncmp_mutex);
> +
> + stream.next_in = src;
> + stream.avail_in = srclen;
> +
> + stream.next_out = dst;
> + stream.avail_out = dstlen;
> +
> + err = zlib_inflateReset(&stream);
> + if (err != Z_OK) {
> + printk(KERN_ERR "zlib_inflateReset error %d\n", err);
> + zlib_inflateEnd(&stream);
> + zlib_inflateInit(&stream);
> + }
> +
> + err = zlib_inflate(&stream, Z_FINISH);
> + if (err != Z_STREAM_END)
> + goto err;
> +
> + out = stream.total_out;
> +
> + mutex_unlock(&axfs_uncmp_mutex);
> +
> + return out;
> +
> +err:
> +
> + mutex_unlock(&axfs_uncmp_mutex);
> +
> + printk(KERN_ERR "Error %d while decompressing!\n", err);
> + printk(KERN_ERR "%p(%d)->%p(%d)\n", src, srclen, dst, dstlen);
> + return 0;
> +}
> +
> +int axfs_uncompress_init(void)
> +{
> + if (!initialized++) {
> +
> + mutex_init(&axfs_uncmp_mutex);
> +
> + stream.workspace = vmalloc(zlib_inflate_workspacesize());
> + if (!stream.workspace) {
> + initialized = 0;
> + return -ENOMEM;
> + }
> + stream.next_in = NULL;
> + stream.avail_in = 0;
> + zlib_inflateInit(&stream);
> + }
> + return 0;
> +}
> +
> +int axfs_uncompress_exit(void)
> +{
> + if (!--initialized) {
> + zlib_inflateEnd(&stream);
> + vfree(stream.workspace);
> + }
> + return 0;
> +}
axfs_uncompress_init() and axfs_uncompress_exit() are only called during
init and exit of the module, no need for the initialized variable and the
functions can be annotated with __init and __exit.
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