Sent: Friday, December 11, 2020 7:31 PM
> To: 'Eric Biggers' <ebiggers@xxxxxxxxxx>
> Cc: linux-fsdevel@xxxxxxxxxxxxxxx; viro@xxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; pali@xxxxxxxxxx; dsterba@xxxxxxx;
> aaptel@xxxxxxxx; willy@xxxxxxxxxxxxx; rdunlap@xxxxxxxxxxxxx; joe@xxxxxxxxxxx; mark@xxxxxxxxxxxxx; nborisov@xxxxxxxx;
> linux-ntfs-dev@xxxxxxxxxxxxxxxxxxxxx; anton@xxxxxxxxxx; dan.carpenter@xxxxxxxxxx; hch@xxxxxx
> Subject: RE: [PATCH v14 04/10] fs/ntfs3: Add file operations and implementation
>
> From: Eric Biggers <ebiggers@xxxxxxxxxx>
> Sent: Friday, December 4, 2020 9:42 PM
> > To: Konstantin Komarov <almaz.alexandrovich@xxxxxxxxxxxxxxxxxxxx>
> > Cc: linux-fsdevel@xxxxxxxxxxxxxxx; viro@xxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; pali@xxxxxxxxxx; dsterba@xxxxxxx;
> > aaptel@xxxxxxxx; willy@xxxxxxxxxxxxx; rdunlap@xxxxxxxxxxxxx; joe@xxxxxxxxxxx; mark@xxxxxxxxxxxxx; nborisov@xxxxxxxx;
> > linux-ntfs-dev@xxxxxxxxxxxxxxxxxxxxx; anton@xxxxxxxxxx; dan.carpenter@xxxxxxxxxx; hch@xxxxxx
> > Subject: Re: [PATCH v14 04/10] fs/ntfs3: Add file operations and implementation
> >
> > 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
>
> Hi Eric! We plan to swap spinlock to mutex in the next version.
>
> Best regards!
Hi Eric! Changed the global spinlock to the mutexes for each type of compression.
This should resolve the problem. Please check out the V16.
Thanks!
