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From: Eric Biggers <ebiggers@kernel.org>
To: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
Cc: linux-fsdevel@vger.kernel.org, viro@zeniv.linux.org.uk,
	linux-kernel@vger.kernel.org, pali@kernel.org, dsterba@suse.cz,
	aaptel@suse.com, willy@infradead.org, rdunlap@infradead.org,
	joe@perches.com, mark@harmstone.com, nborisov@suse.com,
	linux-ntfs-dev@lists.sourceforge.net, anton@tuxera.com,
	dan.carpenter@oracle.com, hch@lst.de
Subject: Re: [PATCH v14 04/10] fs/ntfs3: Add file operations and implementation
Date: Fri, 4 Dec 2020 10:41:32 -0800
Message-ID: <X8qC3NaNv1kmCO4c@sol.localdomain> (raw)
In-Reply-To: <20201204154600.1546096-5-almaz.alexandrovich@paragon-software.com>

On Fri, Dec 04, 2020 at 06:45:54PM +0300, Konstantin Komarov wrote:
> +/* external compression lzx/xpress */
> +static int decompress_lzx_xpress(struct ntfs_sb_info *sbi, const char *cmpr,
> +				 size_t cmpr_size, void *unc, size_t unc_size,
> +				 u32 frame_size)
> +{
> +	int err;
> +	void *ctx;
> +
> +	if (cmpr_size == unc_size) {
> +		/* frame not compressed */
> +		memcpy(unc, cmpr, unc_size);
> +		return 0;
> +	}
> +
> +	err = 0;
> +	ctx = NULL;
> +	spin_lock(&sbi->compress.lock);
> +	if (frame_size == 0x8000) {
> +		/* LZX: frame compressed */
> +		if (!sbi->compress.lzx) {
> +			/* Lazy initialize lzx decompress context */
> +			spin_unlock(&sbi->compress.lock);
> +			ctx = lzx_allocate_decompressor(0x8000);
> +			if (!ctx)
> +				return -ENOMEM;
> +			if (IS_ERR(ctx)) {
> +				/* should never failed */
> +				err = PTR_ERR(ctx);
> +				goto out;
> +			}
> +
> +			spin_lock(&sbi->compress.lock);
> +			if (!sbi->compress.lzx) {
> +				sbi->compress.lzx = ctx;
> +				ctx = NULL;
> +			}
> +		}
> +
> +		if (lzx_decompress(sbi->compress.lzx, cmpr, cmpr_size, unc,
> +				   unc_size)) {
> +			err = -EINVAL;
> +		}
> +	} else {
> +		/* XPRESS: frame compressed */
> +		if (!sbi->compress.xpress) {
> +			/* Lazy initialize xpress decompress context */
> +			spin_unlock(&sbi->compress.lock);
> +			ctx = xpress_allocate_decompressor();
> +			if (!ctx)
> +				return -ENOMEM;
> +
> +			spin_lock(&sbi->compress.lock);
> +			if (!sbi->compress.xpress) {
> +				sbi->compress.xpress = ctx;
> +				ctx = NULL;
> +			}
> +		}
> +
> +		if (xpress_decompress(sbi->compress.xpress, cmpr, cmpr_size,
> +				      unc, unc_size)) {
> +			err = -EINVAL;
> +		}
> +	}
> +	spin_unlock(&sbi->compress.lock);
> +out:
> +	ntfs_free(ctx);
> +	return err;
> +}

Decompression is a somewhat heavyweight operation.  Not the type of thing that
should be done while holding a spin lock.

- Eric

  reply index

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-04 15:45 [PATCH v14 00/10] NTFS read-write driver GPL implementation by Paragon Software Konstantin Komarov
2020-12-04 15:45 ` [PATCH v14 01/10] fs/ntfs3: Add headers and misc files Konstantin Komarov
2020-12-04 15:45 ` [PATCH v14 02/10] fs/ntfs3: Add initialization of super block Konstantin Komarov
2020-12-04 15:45 ` [PATCH v14 03/10] fs/ntfs3: Add bitmap Konstantin Komarov
2020-12-04 15:45 ` [PATCH v14 04/10] fs/ntfs3: Add file operations and implementation Konstantin Komarov
2020-12-04 18:41   ` Eric Biggers [this message]
2020-12-11 16:31     ` Konstantin Komarov
2020-12-25 14:27       ` Konstantin Komarov
2020-12-04 15:45 ` [PATCH v14 05/10] fs/ntfs3: Add attrib operations Konstantin Komarov
2020-12-04 15:45 ` [PATCH v14 06/10] fs/ntfs3: Add compression Konstantin Komarov
2020-12-04 18:38   ` Eric Biggers
2020-12-11 16:28     ` Konstantin Komarov
2020-12-25 14:29       ` Konstantin Komarov
2020-12-04 15:45 ` [PATCH v14 07/10] fs/ntfs3: Add NTFS journal Konstantin Komarov
2020-12-04 15:45 ` [PATCH v14 08/10] fs/ntfs3: Add Kconfig, Makefile and doc Konstantin Komarov
2020-12-04 15:45 ` [PATCH v14 09/10] fs/ntfs3: Add NTFS3 in fs/Kconfig and fs/Makefile Konstantin Komarov
2020-12-04 18:51   ` kernel test robot
2020-12-05  0:41   ` kernel test robot
2020-12-04 15:46 ` [PATCH v14 10/10] fs/ntfs3: Add MAINTAINERS Konstantin Komarov

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