AcoSail/kernel_optimize_test
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btrfs: Reduce critical section in btrfs_init_dev_replace_tgtdev

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There is no point in holding btrfs_fs_devices::device_list_mutex
while initialising fields of the not-yet-published device. Instead,
hold the mutex only when the newly initialised device is being
published. I think holding device_list_mutex here is redundant
altogether, because at this point BTRFS_FS_EXCL_OP is set which
prevents device removal/addition/balance/resize to occur.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Nikolay Borisov 2019-05-14 13:54:39 +03:00 committed by David Sterba
parent ddb9378469
commit b0d9e1ea17
1 changed files with 2 additions and 1 deletions
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3
fs/btrfs/dev-replace.c
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@ -237,7 +237,6 @@ static int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
}
rcu_assign_pointer(device->name, name);
mutex_lock(&fs_info->fs_devices->device_list_mutex);
set_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state);
device->generation = 0;
device->io_width = fs_info->sectorsize;
@ -256,6 +255,8 @@ static int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
device->dev_stats_valid = 1;
set_blocksize(device->bdev, BTRFS_BDEV_BLOCKSIZE);
device->fs_devices = fs_info->fs_devices;
mutex_lock(&fs_info->fs_devices->device_list_mutex);
list_add(&device->dev_list, &fs_info->fs_devices->devices);
fs_info->fs_devices->num_devices++;
fs_info->fs_devices->open_devices++;