This was a request from the systemd guys. They need a quick and easy way to get
all devices attached to a Btrfs filesystem in order to check if any of the disks
are SSD for...something, I didn't ask :). I've tested this with the
btrfs-progs patch that accompanies this patch. Thanks,
Signed-off-by: Josef Bacik <jo...@redhat.com>
---
fs/btrfs/ioctl.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
fs/btrfs/ioctl.h | 7 ++++++
2 files changed, 71 insertions(+), 0 deletions(-)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 9254b3d..f59b0bc 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1957,6 +1957,68 @@ out:
return ret;
}
+static noinline long btrfs_ioctl_disk_info(struct btrfs_root *root,
+ void __user *arg)
+{
+ struct btrfs_ioctl_disk_info_args di_args;
+ u64 *user_dest;
+ u64 *dest = NULL;
+ struct btrfs_device *device;
+ struct list_head *devices;
+ int alloc_size = 0;
+ int ret = 0;
+
+ if (copy_from_user(&di_args,
+ (struct btrfs_ioctl_disk_info_args __user *)arg,
+ sizeof(di_args)))
+ return -EFAULT;
+
+ mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
+ if (!di_args.num_devices) {
+ di_args.num_devices = root->fs_info->fs_devices->num_devices;
+ goto out;
+ }
+ alloc_size = sizeof(u64) * di_args.num_devices;
+
+ di_args.num_devices = 0;
+
+ /*
+ * If we have more than 4k worth of space to hold a bunch of u64's,
+ * somebody is misbehaving.
+ */
+ if (alloc_size > PAGE_CACHE_SIZE) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ dest = kzalloc(alloc_size, GFP_NOFS);
+ if (!dest) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ devices = &root->fs_info->fs_devices->devices;
+
+ list_for_each_entry(device, devices, dev_list) {
+ dest[di_args.num_devices] =
+ huge_encode_dev(device->bdev->bd_dev);
+ di_args.num_devices++;
+ }
+
+ user_dest = (u64 *)
+ (arg + sizeof(struct btrfs_ioctl_disk_info_args));
+
+ if (copy_to_user(user_dest, dest, alloc_size))
+ ret = -EFAULT;
+out:
+ mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
+ if (ret == 0 && copy_to_user(arg, &di_args, sizeof(di_args)))
+ ret = -EFAULT;
+ kfree(dest);
+
+ return ret;
+}
+
/*
* there are many ways the trans_start and trans_end ioctls can lead
* to deadlocks. They should only be used by applications that
@@ -2031,6 +2093,8 @@ long btrfs_ioctl(struct file *file, unsigned int
return btrfs_ioctl_ino_lookup(file, argp);
case BTRFS_IOC_SPACE_INFO:
return btrfs_ioctl_space_info(root, argp);
+ case BTRFS_IOC_DISK_INFO:
+ return btrfs_ioctl_disk_info(root, argp);
case BTRFS_IOC_SYNC:
btrfs_sync_fs(file->f_dentry->d_sb, 1);
return 0;
diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
index 424694a..294e8c3 100644
--- a/fs/btrfs/ioctl.h
+++ b/fs/btrfs/ioctl.h
@@ -138,6 +138,11 @@ struct btrfs_ioctl_space_args {
struct btrfs_ioctl_space_info spaces[0];
};
+struct btrfs_ioctl_disk_info_args {
+ __u32 num_devices;
+ __u64 devices[0];
+};
+
#define BTRFS_IOC_SNAP_CREATE _IOW(BTRFS_IOCTL_MAGIC, 1, \
struct btrfs_ioctl_vol_args)
#define BTRFS_IOC_DEFRAG _IOW(BTRFS_IOCTL_MAGIC, 2, \
@@ -178,4 +183,6 @@ struct btrfs_ioctl_space_args {
#define BTRFS_IOC_DEFAULT_SUBVOL _IOW(BTRFS_IOCTL_MAGIC, 19, u64)
#define BTRFS_IOC_SPACE_INFO _IOWR(BTRFS_IOCTL_MAGIC, 20, \
struct btrfs_ioctl_space_args)
+#define BTRFS_IOC_DISK_INFO _IOWR(BTRFS_IOCTL_MAGIC, 21, \
+ struct btrfs_ioctl_disk_info_args)
#endif
--
1.6.6.1
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