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staging: zram: fix zram locking

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Currently init_lock only prevents concurrent execution of zram_init_device()
and zram_reset_device() but not zram_make_request() nor sysfs store functions.

This patch changes init_lock into a rw_semaphore. A write lock is taken by
init, reset and store functions, a read lock is taken by zram_make_request().
Also, avoids to release the lock before calling __zram_reset_device() for
cleaning after a failed init, thus preventing any concurrent task to see an
inconsistent state of zram.

Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Jerome Marchand 2011-09-06 15:02:11 +02:00 committed by Greg Kroah-Hartman
parent a1c821ae6c
commit 0900beae17
3 changed files with 44 additions and 26 deletions
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46
drivers/staging/zram/zram_drv.c
View file

@ -560,27 +560,34 @@ static int zram_make_request(struct request_queue *queue, struct bio *bio)
{
struct zram *zram = queue->queuedata;
if (unlikely(!zram->init_done) && zram_init_device(zram))
goto error;
down_read(&zram->init_lock);
if (unlikely(!zram->init_done))
goto error_unlock;
if (!valid_io_request(zram, bio)) {
zram_stat64_inc(zram, &zram->stats.invalid_io);
bio_io_error(bio);
return 0;
}
if (unlikely(!zram->init_done) && zram_init_device(zram)) {
bio_io_error(bio);
return 0;
goto error_unlock;
}
__zram_make_request(zram, bio, bio_data_dir(bio));
up_read(&zram->init_lock);
return 0;
error_unlock:
up_read(&zram->init_lock);
error:
bio_io_error(bio);
return 0;
}
void zram_reset_device(struct zram *zram)
void __zram_reset_device(struct zram *zram)
{
size_t index;
mutex_lock(&zram->init_lock);
zram->init_done = 0;
/* Free various per-device buffers */
@ -617,7 +624,13 @@ void zram_reset_device(struct zram *zram)
memset(&zram->stats, 0, sizeof(zram->stats));
zram->disksize = 0;
mutex_unlock(&zram->init_lock);
}
void zram_reset_device(struct zram *zram)
{
down_write(&zram->init_lock);
__zram_reset_device(zram);
up_write(&zram->init_lock);
}
int zram_init_device(struct zram *zram)
@ -625,10 +638,10 @@ int zram_init_device(struct zram *zram)
int ret;
size_t num_pages;
mutex_lock(&zram->init_lock);
down_write(&zram->init_lock);
if (zram->init_done) {
mutex_unlock(&zram->init_lock);
up_write(&zram->init_lock);
return 0;
}
@ -671,15 +684,14 @@ int zram_init_device(struct zram *zram)
}
zram->init_done = 1;
mutex_unlock(&zram->init_lock);
up_write(&zram->init_lock);
pr_debug("Initialization done!\n");
return 0;
fail:
mutex_unlock(&zram->init_lock);
zram_reset_device(zram);
__zram_reset_device(zram);
up_write(&zram->init_lock);
pr_err("Initialization failed: err=%d\n", ret);
return ret;
}
@ -703,7 +715,7 @@ static int create_device(struct zram *zram, int device_id)
int ret = 0;
init_rwsem(&zram->lock);
mutex_init(&zram->init_lock);
init_rwsem(&zram->init_lock);
spin_lock_init(&zram->stat64_lock);
zram->queue = blk_alloc_queue(GFP_KERNEL);

6
drivers/staging/zram/zram_drv.h
View file

@ -112,8 +112,8 @@ struct zram {
struct request_queue *queue;
struct gendisk *disk;
int init_done;
/* Prevent concurrent execution of device init and reset */
struct mutex init_lock;
/* Prevent concurrent execution of device init, reset and R/W request */
struct rw_semaphore init_lock;
/*
* This is the limit on amount of *uncompressed* worth of data
* we can store in a disk.
@ -130,6 +130,6 @@ extern struct attribute_group zram_disk_attr_group;
#endif
extern int zram_init_device(struct zram *zram);
extern void zram_reset_device(struct zram *zram);
extern void __zram_reset_device(struct zram *zram);
#endif

18
drivers/staging/zram/zram_sysfs.c
View file

@ -55,19 +55,23 @@ static ssize_t disksize_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t len)
{
int ret;
u64 disksize;
struct zram *zram = dev_to_zram(dev);
ret = strict_strtoull(buf, 10, &disksize);
if (ret)
return ret;
down_write(&zram->init_lock);
if (zram->init_done) {
up_write(&zram->init_lock);
pr_info("Cannot change disksize for initialized device\n");
return -EBUSY;
}
ret = strict_strtoull(buf, 10, &zram->disksize);
if (ret)
return ret;
zram->disksize = PAGE_ALIGN(zram->disksize);
zram->disksize = PAGE_ALIGN(disksize);
set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
up_write(&zram->init_lock);
return len;
}
@ -106,8 +110,10 @@ static ssize_t reset_store(struct device *dev,
if (bdev)
fsync_bdev(bdev);
down_write(&zram->init_lock);
if (zram->init_done)
zram_reset_device(zram);
__zram_reset_device(zram);
up_write(&zram->init_lock);
return len;
}