From 1ca69c4bc4b1ef889861db39f325901eadbf9497 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Thu, 11 Oct 2012 13:37:33 +1100 Subject: md: avoid taking the mutex on some ioctls. Some ioctls don't need to take the mutex and doing so can cause a delay as it is held during super-block update. So move those ioctls out of the mutex and rely on rcu locking to ensure we don't access stale data. Signed-off-by: NeilBrown --- drivers/md/md.c | 85 +++++++++++++++++++++++++++++++++++++++++---------------- 1 file changed, 62 insertions(+), 23 deletions(-) (limited to 'drivers') diff --git a/drivers/md/md.c b/drivers/md/md.c index 8e842b326eb..feab588adb5 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -674,7 +674,18 @@ static struct md_rdev * find_rdev_nr(struct mddev *mddev, int nr) return NULL; } -static struct md_rdev * find_rdev(struct mddev * mddev, dev_t dev) +static struct md_rdev *find_rdev_nr_rcu(struct mddev *mddev, int nr) +{ + struct md_rdev *rdev; + + rdev_for_each_rcu(rdev, mddev) + if (rdev->desc_nr == nr) + return rdev; + + return NULL; +} + +static struct md_rdev *find_rdev(struct mddev *mddev, dev_t dev) { struct md_rdev *rdev; @@ -685,6 +696,17 @@ static struct md_rdev * find_rdev(struct mddev * mddev, dev_t dev) return NULL; } +static struct md_rdev *find_rdev_rcu(struct mddev *mddev, dev_t dev) +{ + struct md_rdev *rdev; + + rdev_for_each_rcu(rdev, mddev) + if (rdev->bdev->bd_dev == dev) + return rdev; + + return NULL; +} + static struct md_personality *find_pers(int level, char *clevel) { struct md_personality *pers; @@ -5509,8 +5531,9 @@ static int get_array_info(struct mddev * mddev, void __user * arg) int nr,working,insync,failed,spare; struct md_rdev *rdev; - nr=working=insync=failed=spare=0; - rdev_for_each(rdev, mddev) { + nr = working = insync = failed = spare = 0; + rcu_read_lock(); + rdev_for_each_rcu(rdev, mddev) { nr++; if (test_bit(Faulty, &rdev->flags)) failed++; @@ -5522,6 +5545,7 @@ static int get_array_info(struct mddev * mddev, void __user * arg) spare++; } } + rcu_read_unlock(); info.major_version = mddev->major_version; info.minor_version = mddev->minor_version; @@ -5605,7 +5629,8 @@ static int get_disk_info(struct mddev * mddev, void __user * arg) if (copy_from_user(&info, arg, sizeof(info))) return -EFAULT; - rdev = find_rdev_nr(mddev, info.number); + rcu_read_lock(); + rdev = find_rdev_nr_rcu(mddev, info.number); if (rdev) { info.major = MAJOR(rdev->bdev->bd_dev); info.minor = MINOR(rdev->bdev->bd_dev); @@ -5624,6 +5649,7 @@ static int get_disk_info(struct mddev * mddev, void __user * arg) info.raid_disk = -1; info.state = (1<pers == NULL) return -ENODEV; - rdev = find_rdev(mddev, dev); + rcu_read_lock(); + rdev = find_rdev_rcu(mddev, dev); if (!rdev) - return -ENODEV; - - md_error(mddev, rdev); - if (!test_bit(Faulty, &rdev->flags)) - return -EBUSY; - return 0; + err = -ENODEV; + else { + md_error(mddev, rdev); + if (!test_bit(Faulty, &rdev->flags)) + err = -EBUSY; + } + rcu_read_unlock(); + return err; } /* @@ -6315,6 +6345,27 @@ static int md_ioctl(struct block_device *bdev, fmode_t mode, goto abort; } + /* Some actions do not requires the mutex */ + switch (cmd) { + case GET_ARRAY_INFO: + if (!mddev->raid_disks && !mddev->external) + err = -ENODEV; + else + err = get_array_info(mddev, argp); + goto abort; + + case GET_DISK_INFO: + if (!mddev->raid_disks && !mddev->external) + err = -ENODEV; + else + err = get_disk_info(mddev, argp); + goto abort; + + case SET_DISK_FAULTY: + err = set_disk_faulty(mddev, new_decode_dev(arg)); + goto abort; + } + err = mddev_lock(mddev); if (err) { printk(KERN_INFO @@ -6387,18 +6438,10 @@ static int md_ioctl(struct block_device *bdev, fmode_t mode, */ switch (cmd) { - case GET_ARRAY_INFO: - err = get_array_info(mddev, argp); - goto done_unlock; - case GET_BITMAP_FILE: err = get_bitmap_file(mddev, argp); goto done_unlock; - case GET_DISK_INFO: - err = get_disk_info(mddev, argp); - goto done_unlock; - case RESTART_ARRAY_RW: err = restart_array(mddev); goto done_unlock; @@ -6480,10 +6523,6 @@ static int md_ioctl(struct block_device *bdev, fmode_t mode, err = hot_add_disk(mddev, new_decode_dev(arg)); goto done_unlock; - case SET_DISK_FAULTY: - err = set_disk_faulty(mddev, new_decode_dev(arg)); - goto done_unlock; - case RUN_ARRAY: err = do_md_run(mddev); goto done_unlock; -- cgit v1.2.3