diff --git a/Documentation/blockdev/zram.txt b/Documentation/blockdev/zram.txt index 13100fb3c26df99317a6ddd8acc9ec0fa85ed0dd..7c05357360a763371fd4396b049f48092815797d 100644 --- a/Documentation/blockdev/zram.txt +++ b/Documentation/blockdev/zram.txt @@ -83,6 +83,17 @@ pre-created. Default: 1. #select lzo compression algorithm echo lzo > /sys/block/zram0/comp_algorithm + For the time being, the `comp_algorithm' content does not necessarily + show every compression algorithm supported by the kernel. We keep this + list primarily to simplify device configuration and one can configure + a new device with a compression algorithm that is not listed in + `comp_algorithm'. The thing is that, internally, ZRAM uses Crypto API + and, if some of the algorithms were built as modules, it's impossible + to list all of them using, for instance, /proc/crypto or any other + method. This, however, has an advantage of permitting the usage of + custom crypto compression modules (implementing S/W or H/W + compression). + 4) Set Disksize Set disk size by writing the value to sysfs node 'disksize'. The value can be either in bytes or you can use mem suffixes. diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c index f35726860a1ba85e1824c6e21047317958fa2ecb..a2b4eb85b41d47f7bcab4f0d8622b2439eaf9777 100644 --- a/drivers/block/zram/zcomp.c +++ b/drivers/block/zram/zcomp.c @@ -26,17 +26,6 @@ static const char * const backends[] = { NULL }; -static const char *find_backend(const char *compress) -{ - int i = 0; - while (backends[i]) { - if (sysfs_streq(compress, backends[i])) - break; - i++; - } - return backends[i]; -} - static void zcomp_strm_free(struct zcomp_strm *zstrm) { if (!IS_ERR_OR_NULL(zstrm->tfm)) @@ -68,30 +57,56 @@ static struct zcomp_strm *zcomp_strm_alloc(struct zcomp *comp, gfp_t flags) return zstrm; } +bool zcomp_available_algorithm(const char *comp) +{ + int i = 0; + + while (backends[i]) { + if (sysfs_streq(comp, backends[i])) + return true; + i++; + } + + /* + * Crypto does not ignore a trailing new line symbol, + * so make sure you don't supply a string containing + * one. + * This also means that we permit zcomp initialisation + * with any compressing algorithm known to crypto api. + */ + return crypto_has_comp(comp, 0, 0) == 1; +} + /* show available compressors */ ssize_t zcomp_available_show(const char *comp, char *buf) { + bool known_algorithm = false; ssize_t sz = 0; int i = 0; - while (backends[i]) { - if (!strcmp(comp, backends[i])) + for (; backends[i]; i++) { + if (!strcmp(comp, backends[i])) { + known_algorithm = true; sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2, "[%s] ", backends[i]); - else + } else { sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2, "%s ", backends[i]); - i++; + } } + + /* + * Out-of-tree module known to crypto api or a missing + * entry in `backends'. + */ + if (!known_algorithm && crypto_has_comp(comp, 0, 0) == 1) + sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2, + "[%s] ", comp); + sz += scnprintf(buf + sz, PAGE_SIZE - sz, "\n"); return sz; } -bool zcomp_available_algorithm(const char *comp) -{ - return find_backend(comp) != NULL; -} - struct zcomp_strm *zcomp_stream_get(struct zcomp *comp) { return *get_cpu_ptr(comp->stream); @@ -227,18 +242,16 @@ void zcomp_destroy(struct zcomp *comp) struct zcomp *zcomp_create(const char *compress) { struct zcomp *comp; - const char *backend; int error; - backend = find_backend(compress); - if (!backend) + if (!zcomp_available_algorithm(compress)) return ERR_PTR(-EINVAL); comp = kzalloc(sizeof(struct zcomp), GFP_KERNEL); if (!comp) return ERR_PTR(-ENOMEM); - comp->name = backend; + comp->name = compress; error = zcomp_init(comp); if (error) { kfree(comp); diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 65d140336289d454d592d336e3495fbb9072f06b..c2a1d7dbaec90a4e0fdf7f632c89ccd5dd624763 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -342,9 +342,16 @@ static ssize_t comp_algorithm_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t len) { struct zram *zram = dev_to_zram(dev); + char compressor[CRYPTO_MAX_ALG_NAME]; size_t sz; - if (!zcomp_available_algorithm(buf)) + strlcpy(compressor, buf, sizeof(compressor)); + /* ignore trailing newline */ + sz = strlen(compressor); + if (sz > 0 && compressor[sz - 1] == '\n') + compressor[sz - 1] = 0x00; + + if (!zcomp_available_algorithm(compressor)) return -EINVAL; down_write(&zram->init_lock); @@ -353,13 +360,8 @@ static ssize_t comp_algorithm_store(struct device *dev, pr_info("Can't change algorithm for initialized device\n"); return -EBUSY; } - strlcpy(zram->compressor, buf, sizeof(zram->compressor)); - - /* ignore trailing newline */ - sz = strlen(zram->compressor); - if (sz > 0 && zram->compressor[sz - 1] == '\n') - zram->compressor[sz - 1] = 0x00; + strlcpy(zram->compressor, compressor, sizeof(compressor)); up_write(&zram->init_lock); return len; } diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h index 3f5bf66a27e45aa5bb6f6bc14da5ac35855dec14..74fcf10da37499a610d99f3381878b75546ea24d 100644 --- a/drivers/block/zram/zram_drv.h +++ b/drivers/block/zram/zram_drv.h @@ -15,8 +15,9 @@ #ifndef _ZRAM_DRV_H_ #define _ZRAM_DRV_H_ -#include +#include #include +#include #include "zcomp.h" @@ -113,7 +114,7 @@ struct zram { * we can store in a disk. */ u64 disksize; /* bytes */ - char compressor[10]; + char compressor[CRYPTO_MAX_ALG_NAME]; /* * zram is claimed so open request will be failed */