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zram: propagate error to user

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When we initialized zcomp with single, we couldn't change
max_comp_streams without zram reset but current interface doesn't show
any error to user and even it changes max_comp_streams's value without
any effect so it would make user very confusing.

This patch prevents max_comp_streams's change when zcomp was initialized
as single zcomp and emit the error to user(ex, echo).

[akpm@linux-foundation.org: don't return with the lock held, per Sergey]
[fengguang.wu@intel.com: fix coccinelle warnings]
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Jerome Marchand <jmarchan@redhat.com>
Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Minchan Kim 2014-04-07 15:38:21 -07:00 committed by Linus Torvalds
parent fcfa8d95ca
commit 60a726e333
4 changed files with 25 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
Documentation/blockdev/zram.txt
View File

@ -37,10 +37,11 @@ Note:
In order to enable compression backend's multi stream support max_comp_streams
must be initially set to desired concurrency level before ZRAM device
initialisation. Once the device initialised as a single stream compression
backend (max_comp_streams equals to 0) changing the value of max_comp_streams
will not take any effect, because single stream compression backend implemented
as a special case and does not support dynamic max_comp_streams. Only multi
stream backend supports dynamic max_comp_streams adjustment.
backend (max_comp_streams equals to 1), you will see error if you try to change
the value of max_comp_streams because single stream compression backend
implemented as a special case by lock overhead issue and does not support
dynamic max_comp_streams. Only multi stream backend supports dynamic
max_comp_streams adjustment.
3) Select compression algorithm
Using comp_algorithm device attribute one can see available and

10
drivers/block/zram/zcomp.c
View File

@ -153,7 +153,7 @@ static void zcomp_strm_multi_release(struct zcomp *comp, struct zcomp_strm *zstr
}
/* change max_strm limit */
static int zcomp_strm_multi_set_max_streams(struct zcomp *comp, int num_strm)
static bool zcomp_strm_multi_set_max_streams(struct zcomp *comp, int num_strm)
{
struct zcomp_strm_multi *zs = comp->stream;
struct zcomp_strm *zstrm;
@ -172,7 +172,7 @@ static int zcomp_strm_multi_set_max_streams(struct zcomp *comp, int num_strm)
zs->avail_strm--;
}
spin_unlock(&zs->strm_lock);
return 0;
return true;
}
static void zcomp_strm_multi_destroy(struct zcomp *comp)
@ -232,10 +232,10 @@ static void zcomp_strm_single_release(struct zcomp *comp,
mutex_unlock(&zs->strm_lock);
}
static int zcomp_strm_single_set_max_streams(struct zcomp *comp, int num_strm)
static bool zcomp_strm_single_set_max_streams(struct zcomp *comp, int num_strm)
{
/* zcomp_strm_single support only max_comp_streams == 1 */
return -ENOTSUPP;
return false;
}
static void zcomp_strm_single_destroy(struct zcomp *comp)
@ -284,7 +284,7 @@ ssize_t zcomp_available_show(const char *comp, char *buf)
return sz;
}
int zcomp_set_max_streams(struct zcomp *comp, int num_strm)
bool zcomp_set_max_streams(struct zcomp *comp, int num_strm)
{
return comp->set_max_streams(comp, num_strm);
}

4
drivers/block/zram/zcomp.h
View File

@ -46,7 +46,7 @@ struct zcomp {
struct zcomp_strm *(*strm_find)(struct zcomp *comp);
void (*strm_release)(struct zcomp *comp, struct zcomp_strm *zstrm);
int (*set_max_streams)(struct zcomp *comp, int num_strm);
bool (*set_max_streams)(struct zcomp *comp, int num_strm);
void (*destroy)(struct zcomp *comp);
};
@ -64,5 +64,5 @@ int zcomp_compress(struct zcomp *comp, struct zcomp_strm *zstrm,
int zcomp_decompress(struct zcomp *comp, const unsigned char *src,
size_t src_len, unsigned char *dst);
int zcomp_set_max_streams(struct zcomp *comp, int num_strm);
bool zcomp_set_max_streams(struct zcomp *comp, int num_strm);
#endif /* _ZCOMP_H_ */

17
drivers/block/zram/zram_drv.c
View File

@ -127,19 +127,28 @@ static ssize_t max_comp_streams_store(struct device *dev,
{
int num;
struct zram *zram = dev_to_zram(dev);
int ret;
if (kstrtoint(buf, 0, &num))
return -EINVAL;
ret = kstrtoint(buf, 0, &num);
if (ret < 0)
return ret;
if (num < 1)
return -EINVAL;
down_write(&zram->init_lock);
if (init_done(zram)) {
if (zcomp_set_max_streams(zram->comp, num))
if (!zcomp_set_max_streams(zram->comp, num)) {
pr_info("Cannot change max compression streams\n");
ret = -EINVAL;
goto out;
}
}
zram->max_comp_streams = num;
ret = len;
out:
up_write(&zram->init_lock);
return len;
return ret;
}
static ssize_t comp_algorithm_show(struct device *dev,