| Message ID | 004920f0f641ebffa974129fe8f4b0d6a9ee9f34.1522780026.git.dsterba@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
> @@ -2716,6 +2718,7 @@ static long btrfs_ioctl_rm_dev(struct file *file, void __user *arg) > ret = BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS; > goto out_drop_write; > } > + mutex_lock(&fs_info->volume_mutex); > > vol_args = memdup_user(arg, sizeof(*vol_args)); > if (IS_ERR(vol_args)) { > @@ -2730,6 +2733,7 @@ static long btrfs_ioctl_rm_dev(struct file *file, void __user *arg) > btrfs_info(fs_info, "disk deleted %s", vol_args->name); > kfree(vol_args); > out: > + mutex_unlock(&fs_info->volume_mutex); > clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags); > out_drop_write: > mnt_drop_write_file(file); Why not memdup_user() be outside of volume_mutex? But not a big deal either. Reviewed-by: Anand Jain <anand.jain@oracle.com> Thanks, Anand -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Apr 05, 2018 at 05:41:57PM +0800, Anand Jain wrote: > > > @@ -2716,6 +2718,7 @@ static long btrfs_ioctl_rm_dev(struct file *file, void __user *arg) > > ret = BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS; > > goto out_drop_write; > > } > > + mutex_lock(&fs_info->volume_mutex); > > > > vol_args = memdup_user(arg, sizeof(*vol_args)); > > if (IS_ERR(vol_args)) { > @@ -2730,6 +2733,7 @@ static long btrfs_ioctl_rm_dev(struct file > *file, void __user *arg) > > btrfs_info(fs_info, "disk deleted %s", vol_args->name); > > kfree(vol_args); > > out: > > + mutex_unlock(&fs_info->volume_mutex); > > clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags); > > out_drop_write: > > mnt_drop_write_file(file); > > Why not memdup_user() be outside of volume_mutex? The point of the patch is to put the mutex_lock right next to the exclusive operation bit setting. It's not optimal regarding the size of critical section and normally the memdup should be outside. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index ac85e07f567b..b93dea445802 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -2674,6 +2674,7 @@ static long btrfs_ioctl_rm_dev_v2(struct file *file, void __user *arg) ret = BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS; goto out; } + mutex_lock(&fs_info->volume_mutex); if (vol_args->flags & BTRFS_DEVICE_SPEC_BY_ID) { ret = btrfs_rm_device(fs_info, NULL, vol_args->devid); @@ -2681,6 +2682,7 @@ static long btrfs_ioctl_rm_dev_v2(struct file *file, void __user *arg) vol_args->name[BTRFS_SUBVOL_NAME_MAX] = '\0'; ret = btrfs_rm_device(fs_info, vol_args->name, 0); } + mutex_unlock(&fs_info->volume_mutex); clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags); if (!ret) { @@ -2716,6 +2718,7 @@ static long btrfs_ioctl_rm_dev(struct file *file, void __user *arg) ret = BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS; goto out_drop_write; } + mutex_lock(&fs_info->volume_mutex); vol_args = memdup_user(arg, sizeof(*vol_args)); if (IS_ERR(vol_args)) { @@ -2730,6 +2733,7 @@ static long btrfs_ioctl_rm_dev(struct file *file, void __user *arg) btrfs_info(fs_info, "disk deleted %s", vol_args->name); kfree(vol_args); out: + mutex_unlock(&fs_info->volume_mutex); clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags); out_drop_write: mnt_drop_write_file(file); diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index df2d6d06e014..e0bd181dc9e0 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -1932,7 +1932,6 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info, const char *device_path, u64 num_devices; int ret = 0; - mutex_lock(&fs_info->volume_mutex); mutex_lock(&uuid_mutex); num_devices = fs_info->fs_devices->num_devices; @@ -2048,7 +2047,6 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info, const char *device_path, out: mutex_unlock(&uuid_mutex); - mutex_unlock(&fs_info->volume_mutex); return ret; error_undo:
Move locking and unlocking next to the BTRFS_FS_EXCL_OP bit manipulation so it's obvious that the two happen at the same time. Signed-off-by: David Sterba <dsterba@suse.com> --- fs/btrfs/ioctl.c | 4 ++++ fs/btrfs/volumes.c | 2 -- 2 files changed, 4 insertions(+), 2 deletions(-)