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Date: Tue, 25 Feb 2014 08:14:43 +0900
From: Minchan Kim <minchan@...nel.org>
To: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Cc: Jerome Marchand <jmarchan@...hat.com>,
Nitin Gupta <ngupta@...are.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCHv6 2/6] zram: use zcomp compressing backends
On Mon, Feb 24, 2014 at 11:39:50AM +0300, Sergey Senozhatsky wrote:
> On (02/24/14 10:01), Minchan Kim wrote:
> > On Fri, Feb 21, 2014 at 02:50:39PM +0300, Sergey Senozhatsky wrote:
> > > Do not perform direct LZO compress/decompress calls, initialise
> > > and use zcomp LZO backend (single compression stream) instead.
> > >
> > > Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
> > > ---
> > > drivers/block/zram/Makefile | 2 +-
> > > drivers/block/zram/zram_drv.c | 62 +++++++++++++++++++------------------------
> > > drivers/block/zram/zram_drv.h | 8 +++---
> > > 3 files changed, 32 insertions(+), 40 deletions(-)
> > >
> > > diff --git a/drivers/block/zram/Makefile b/drivers/block/zram/Makefile
> > > index cb0f9ce..757c6a5 100644
> > > --- a/drivers/block/zram/Makefile
> > > +++ b/drivers/block/zram/Makefile
> > > @@ -1,3 +1,3 @@
> > > -zram-y := zram_drv.o
> > > +zram-y := zcomp_lzo.o zcomp.o zram_drv.o
> > >
> > > obj-$(CONFIG_ZRAM) += zram.o
> > > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> > > index 9baac5b..200c12a 100644
> > > --- a/drivers/block/zram/zram_drv.c
> > > +++ b/drivers/block/zram/zram_drv.c
> > > @@ -29,15 +29,14 @@
> > > #include <linux/genhd.h>
> > > #include <linux/highmem.h>
> > > #include <linux/slab.h>
> > > -#include <linux/lzo.h>
> > > #include <linux/string.h>
> > > -#include <linux/vmalloc.h>
> >
> > In ARM,
> >
> > drivers/block/zram/zram_drv.c:161:2: error: implicit declaration of function 'vfree'
> > drivers/block/zram/zram_drv.c:173:2: error: implicit declaration of function 'vzalloc'
> >
>
> will address, thanks.
>
> > >
> > > #include "zram_drv.h"
> > >
> > > /* Globals */
> > > static int zram_major;
> > > static struct zram *zram_devices;
> > > +static const char *default_compressor = "lzo";
> > >
> > > /* Module params (documentation at end) */
> > > static unsigned int num_devices = 1;
> > > @@ -160,8 +159,6 @@ static inline int valid_io_request(struct zram *zram, struct bio *bio)
> > > static void zram_meta_free(struct zram_meta *meta)
> > > {
> > > zs_destroy_pool(meta->mem_pool);
> > > - kfree(meta->compress_workmem);
> > > - free_pages((unsigned long)meta->compress_buffer, 1);
> > > vfree(meta->table);
> > > kfree(meta);
> > > }
> > > @@ -173,22 +170,11 @@ static struct zram_meta *zram_meta_alloc(u64 disksize)
> > > if (!meta)
> > > goto out;
> > >
> > > - meta->compress_workmem = kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
> > > - if (!meta->compress_workmem)
> > > - goto free_meta;
> > > -
> > > - meta->compress_buffer =
> > > - (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
> > > - if (!meta->compress_buffer) {
> > > - pr_err("Error allocating compressor buffer space\n");
> > > - goto free_workmem;
> > > - }
> > > -
> > > num_pages = disksize >> PAGE_SHIFT;
> > > meta->table = vzalloc(num_pages * sizeof(*meta->table));
> > > if (!meta->table) {
> > > pr_err("Error allocating zram address table\n");
> > > - goto free_buffer;
> > > + goto free_meta;
> > > }
> > >
> > > meta->mem_pool = zs_create_pool(GFP_NOIO | __GFP_HIGHMEM);
> > > @@ -198,15 +184,10 @@ static struct zram_meta *zram_meta_alloc(u64 disksize)
> > > }
> > >
> > > rwlock_init(&meta->tb_lock);
> > > - mutex_init(&meta->buffer_lock);
> > > return meta;
> > >
> > > free_table:
> > > vfree(meta->table);
> > > -free_buffer:
> > > - free_pages((unsigned long)meta->compress_buffer, 1);
> > > -free_workmem:
> > > - kfree(meta->compress_workmem);
> > > free_meta:
> > > kfree(meta);
> > > meta = NULL;
> > > @@ -280,8 +261,7 @@ static void zram_free_page(struct zram *zram, size_t index)
> > >
> > > static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
> > > {
> > > - int ret = LZO_E_OK;
> > > - size_t clen = PAGE_SIZE;
> > > + int ret = 0;
> > > unsigned char *cmem;
> > > struct zram_meta *meta = zram->meta;
> > > unsigned long handle;
> > > @@ -301,12 +281,12 @@ static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
> > > if (size == PAGE_SIZE)
> > > copy_page(mem, cmem);
> > > else
> > > - ret = lzo1x_decompress_safe(cmem, size, mem, &clen);
> > > + ret = zcomp_decompress(zram->comp, cmem, size, mem);
> > > zs_unmap_object(meta->mem_pool, handle);
> > > read_unlock(&meta->tb_lock);
> > >
> > > /* Should NEVER happen. Return bio error if it does. */
> > > - if (unlikely(ret != LZO_E_OK)) {
> > > + if (unlikely(ret)) {
> > > pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
> > > atomic64_inc(&zram->stats.failed_reads);
> > > return ret;
> > > @@ -349,7 +329,7 @@ static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
> > >
> > > ret = zram_decompress_page(zram, uncmem, index);
> > > /* Should NEVER happen. Return bio error if it does. */
> > > - if (unlikely(ret != LZO_E_OK))
> > > + if (unlikely(ret))
> > > goto out_cleanup;
> > >
> > > if (is_partial_io(bvec))
> > > @@ -374,11 +354,10 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
> > > struct page *page;
> > > unsigned char *user_mem, *cmem, *src, *uncmem = NULL;
> > > struct zram_meta *meta = zram->meta;
> > > + struct zcomp_strm *zstrm;
> > > bool locked = false;
> > >
> > > page = bvec->bv_page;
> > > - src = meta->compress_buffer;
> > > -
> > > if (is_partial_io(bvec)) {
> > > /*
> > > * This is a partial IO. We need to read the full page
> > > @@ -394,7 +373,7 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
> > > goto out;
> > > }
> > >
> > > - mutex_lock(&meta->buffer_lock);
> > > + zstrm = zcomp_strm_get(zram->comp);
> > > locked = true;
> > > user_mem = kmap_atomic(page);
> > >
> > > @@ -420,19 +399,18 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
> > > goto out;
> > > }
> > >
> > > - ret = lzo1x_1_compress(uncmem, PAGE_SIZE, src, &clen,
> > > - meta->compress_workmem);
> > > + ret = zcomp_compress(zram->comp, zstrm, uncmem, &clen);
> > > if (!is_partial_io(bvec)) {
> > > kunmap_atomic(user_mem);
> > > user_mem = NULL;
> > > uncmem = NULL;
> > > }
> > >
> > > - if (unlikely(ret != LZO_E_OK)) {
> > > + if (unlikely(ret)) {
> > > pr_err("Compression failed! err=%d\n", ret);
> > > goto out;
> > > }
> > > -
> > > + src = zstrm->buffer;
> > > if (unlikely(clen > max_zpage_size)) {
> > > clen = PAGE_SIZE;
> > > src = NULL;
> >
> > Do we need this line? src = NULL?
>
> not really.
>
> > > @@ -457,6 +435,8 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
> > > memcpy(cmem, src, clen);
> > > }
> > >
> > > + zcomp_strm_put(zram->comp, zstrm);
> > > + locked = false;
> > > zs_unmap_object(meta->mem_pool, handle);
> > >
> > > /*
> > > @@ -475,10 +455,9 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
> > > atomic64_inc(&zram->stats.pages_stored);
> > > out:
> > > if (locked)
> > > - mutex_unlock(&meta->buffer_lock);
> > > + zcomp_strm_put(zram->comp, zstrm);
> > > if (is_partial_io(bvec))
> > > kfree(uncmem);
> > > -
> >
> > Unnecessary new line
> >
>
> ok.
>
> > > if (ret)
> > > atomic64_inc(&zram->stats.failed_writes);
> > > return ret;
> > > @@ -522,6 +501,9 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity)
> > > zs_free(meta->mem_pool, handle);
> > > }
> > >
> > > + zcomp_destroy(zram->comp);
> > > + zram->comp = NULL;
> >
> > Just a nitpick:
> > Do we need to reset zram->comp to NULL?
> >
>
> well. not at this time, makes sense with when multi backend support.
> initialise zcomp to default compressor if it still un-initialised via
> compressor device attribute.
Okay, then let's fix this and adding compressor name I suggested in
below error message when we start to support multi backend.
Let's keep in mind. :)
>
> > > +
> > > zram_meta_free(zram->meta);
> > > zram->meta = NULL;
> > > /* Reset stats */
> > > @@ -550,9 +532,18 @@ static ssize_t disksize_store(struct device *dev,
> > > return -EBUSY;
> > > }
> > >
> > > + zram->comp = zcomp_create(default_compressor);
> > > + if (!zram->comp) {
> > > + up_write(&zram->init_lock);
> > > + pr_info("Cannot initialise compressing backend\n");
> >
> > Pz, add compressor name in info.
> >
> > Okay, Now we have only lzo so anyone doesn't confuse but I'm afraid
> > that we forget to fix this when we add new compressor. :(
> >
>
> ok.
>
> > > + return -EINVAL;
> > > + }
> > > +
> > > disksize = PAGE_ALIGN(disksize);
> > > zram->meta = zram_meta_alloc(disksize);
> > > if (!zram->meta) {
> > > + zcomp_destroy(zram->comp);
> > > + zram->comp = NULL;
> >
> > I'd like to know why we need to reset zram->comp to NULL.
> > Do you have in a mind?
> >
>
> same as above. makes sense with multi backend support.
>
> > > up_write(&zram->init_lock);
> > > return -ENOMEM;
> > > }
> > > @@ -790,6 +781,7 @@ static int create_device(struct zram *zram, int device_id)
> > > }
> > >
> > > zram->meta = NULL;
> > > + zram->comp = NULL;
> >
> > Ditto.
> >
> > > return 0;
> > >
> > > out_free_disk:
> > > diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
> > > index 1d5b1f5..45e04f7 100644
> > > --- a/drivers/block/zram/zram_drv.h
> > > +++ b/drivers/block/zram/zram_drv.h
> > > @@ -16,9 +16,10 @@
> > > #define _ZRAM_DRV_H_
> > >
> > > #include <linux/spinlock.h>
> > > -#include <linux/mutex.h>
> > > #include <linux/zsmalloc.h>
> > >
> > > +#include "zcomp.h"
> > > +
> > > /*
> > > * Some arbitrary value. This is just to catch
> > > * invalid value for num_devices module parameter.
> > > @@ -81,17 +82,16 @@ struct zram_stats {
> > >
> > > struct zram_meta {
> > > rwlock_t tb_lock; /* protect table */
> > > - void *compress_workmem;
> > > - void *compress_buffer;
> > > struct table *table;
> > > struct zs_pool *mem_pool;
> > > - struct mutex buffer_lock; /* protect compress buffers */
> > > };
> > >
> > > struct zram {
> > > struct zram_meta *meta;
> > > struct request_queue *queue;
> > > struct gendisk *disk;
> > > + struct zcomp *comp;
> > > +
> > > /* Prevent concurrent execution of device init, reset and R/W request */
> > > struct rw_semaphore init_lock;
> > > /*
> > > --
> >
> > Other than that,
> > Acked-by: Minchan Kim <minchan@...nel.org>
> >
> > --
> > Kind regards,
> > Minchan Kim
> >
> --
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--
Kind regards,
Minchan Kim
--
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