From: Goffredo Baroncelli <kreij...@inwind.it>
Add a new ioctl to get info about chunk without requiring the root privileges.
This allow to a non root user to know how the space of the filesystem is
allocated.
Signed-off-by: Goffredo Baroncelli <kreij...@inwind.it>
---
fs/btrfs/ioctl.c | 215 +++++++++++++++++++++++++++++++++++++++++++++
include/uapi/linux/btrfs.h | 38 ++++++++
2 files changed, 253 insertions(+)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index fa1b78cf25f6..d9ba9ed52693 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2220,6 +2220,219 @@ static noinline int btrfs_ioctl_tree_search_v2(struct
file *file,
return ret;
}
+/*
+ * Return:
+ * 0 -> copied all data, possible further data
+ * 1 -> copied all data, no further data
+ * -EAGAIN -> not enough space, restart it
+ * -EFAULT -> the user passed an invalid address/size pair
+ */
+static noinline int copy_chunk_info(struct btrfs_path *path,
+ char __user *ubuf,
+ size_t buf_size,
+ u64 *used_buf,
+ int *num_found,
+ u64 *offset)
+{
+ struct extent_buffer *leaf;
+ unsigned long item_off;
+ unsigned long item_len;
+ int nritems;
+ int i;
+ int slot;
+ int ret = 0;
+ struct btrfs_key key;
+
+ leaf = path->nodes[0];
+ slot = path->slots[0];
+ nritems = btrfs_header_nritems(leaf);
+
+ for (i = slot; i < nritems; i++) {
+ u64 destsize;
+ struct btrfs_chunk_info ci;
+ struct btrfs_chunk chunk;
+ int j, chunk_size;
+
+ item_off = btrfs_item_ptr_offset(leaf, i);
+ item_len = btrfs_item_size_nr(leaf, i);
+
+ btrfs_item_key_to_cpu(leaf, &key, i);
+ /*
+ * we are not interested in other items type
+ */
+ if (key.type != BTRFS_CHUNK_ITEM_KEY) {
+ ret = 1;
+ goto out;
+ }
+
+ /*
+ * In any case, the next search must start from here
+ */
+ *offset = key.offset;
+ read_extent_buffer(leaf, &chunk, item_off, sizeof(chunk));
+
+ /*
+ * chunk.num_stripes-1 is correct, because btrfs_chunk includes
+ * already a stripe
+ */
+ destsize = sizeof(struct btrfs_chunk_info) +
+ (chunk.num_stripes - 1) * sizeof(struct btrfs_stripe);
+
+ BUG_ON(destsize > item_len);
+
+ if (buf_size < destsize + *used_buf) {
+ if (*num_found)
+ /* try onother time */
+ ret = -EAGAIN;
+ else
+ /* in any case the buffer is too small */
+ ret = -EOVERFLOW;
+ goto out;
+ }
+
+ /* copy chunk */
+ chunk_size = offsetof(struct btrfs_chunk_info, stripes);
+ memset(&ci, 0, chunk_size);
+ ci.length = btrfs_stack_chunk_length(&chunk);
+ ci.stripe_len = btrfs_stack_chunk_stripe_len(&chunk);
+ ci.type = btrfs_stack_chunk_type(&chunk);
+ ci.num_stripes = btrfs_stack_chunk_num_stripes(&chunk);
+ ci.sub_stripes = btrfs_stack_chunk_sub_stripes(&chunk);
+ ci.offset = key.offset;
+
+ if (copy_to_user(ubuf + *used_buf, &ci, chunk_size)) {
+ ret = -EFAULT;
+ goto out;
+ }
+ *used_buf += chunk_size;
+
+ /* copy stripes */
+ for (j = 0 ; j < chunk.num_stripes ; j++) {
+ struct btrfs_stripe chunk_stripe;
+ struct btrfs_chunk_info_stripe csi;
+
+ /*
+ * j-1 is correct, because btrfs_chunk includes already
+ * a stripe
+ */
+ read_extent_buffer(leaf, &chunk_stripe,
+ item_off + sizeof(struct btrfs_chunk) +
+ sizeof(struct btrfs_stripe) *
+ (j - 1), sizeof(chunk_stripe));
+
+ memset(&csi, 0, sizeof(csi));
+
+ csi.devid = btrfs_stack_stripe_devid(&chunk_stripe);
+ csi.offset = btrfs_stack_stripe_offset(&chunk_stripe);
+ memcpy(csi.dev_uuid, chunk_stripe.dev_uuid,
+ sizeof(chunk_stripe.dev_uuid));
+ if (copy_to_user(ubuf + *used_buf, &csi, sizeof(csi))) {
+ ret = -EFAULT;
+ goto out;
+ }
+ *used_buf += sizeof(csi);
+ }
+
+ ++(*num_found);
+ }
+
+ ret = 0;
+ if (*offset < (u64)-1)
+ ++(*offset);
+out:
+ return ret;
+}
+
+static noinline int search_chunk_info(struct inode *inode, u64 *offset,
+ int *items_count,
+ char __user *ubuf, u64 buf_size)
+{
+ struct btrfs_fs_info *info = btrfs_sb(inode->i_sb);
+ struct btrfs_root *root;
+ struct btrfs_key key;
+ struct btrfs_path *path;
+ int ret;
+ u64 used_buf = 0;
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+
+ /* search for BTRFS_CHUNK_TREE_OBJECTID tree */
+ key.objectid = BTRFS_CHUNK_TREE_OBJECTID;
+ key.type = BTRFS_ROOT_ITEM_KEY;
+ key.offset = (u64)-1;
+ root = btrfs_read_fs_root_no_name(info, &key);
+ if (IS_ERR(root)) {
+ btrfs_err(info, "could not find root\n");
+ btrfs_free_path(path);
+ return -ENOENT;
+ }
+
+
+ while (used_buf < buf_size) {
+ key.objectid = 0x0100;
+ key.type = BTRFS_CHUNK_ITEM_KEY;
+ key.offset = *offset;
+
+ ret = btrfs_search_forward(root, &key, path, 0);
+ if (ret != 0) {
+ if (ret > 0)
+ ret = 0;
+ goto ret;
+ }
+
+ ret = copy_chunk_info(path, ubuf, buf_size,
+ &used_buf, items_count, offset);
+
+ btrfs_release_path(path);
+ if (ret)
+ break;
+
+ }
+
+ret:
+ btrfs_free_path(path);
+ return ret;
+}
+
+static noinline int btrfs_ioctl_get_chunk_info(struct file *file,
+ void __user *argp)
+{
+ struct btrfs_ioctl_chunk_info arg;
+ struct inode *inode;
+ int ret;
+ size_t buf_size;
+ u64 data_offset;
+ const size_t buf_limit = SZ_16M;
+
+
+ data_offset = sizeof(struct btrfs_ioctl_chunk_info);
+ inode = file_inode(file);
+
+ if (copy_from_user(&arg, argp, sizeof(arg)))
+ return -EFAULT;
+
+ buf_size = arg.buf_size;
+ arg.items_count = 0;
+
+ if (buf_size < sizeof(struct btrfs_ioctl_chunk_info) +
+ sizeof(struct btrfs_chunk_info))
+ return -EOVERFLOW;
+
+ /* limit result size to 16MB */
+ if (buf_size > buf_limit)
+ buf_size = buf_limit;
+
+ ret = search_chunk_info(inode, &arg.offset, &arg.items_count,
+ argp + data_offset, buf_size - data_offset);
+
+ if (copy_to_user(argp, &arg, data_offset))
+ return -EFAULT;
+
+ return ret;
+}
+
/*
* Search INODE_REFs to identify path name of 'dirid' directory
* in a 'tree_id' tree. and sets path name to 'name'.
@@ -5632,6 +5845,8 @@ long btrfs_ioctl(struct file *file, unsigned int
return btrfs_ioctl_get_features(file, argp);
case BTRFS_IOC_SET_FEATURES:
return btrfs_ioctl_set_features(file, argp);
+ case BTRFS_IOC_GET_CHUNK_INFO:
+ return btrfs_ioctl_get_chunk_info(file, argp);
}
return -ENOTTY;
diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
index 9aa74f317747..2982377a51bd 100644
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -691,6 +691,42 @@ struct btrfs_ioctl_received_subvol_args {
__u64 reserved[16]; /* in */
};
+struct btrfs_chunk_info_stripe {
+ __u64 devid;
+ __u64 offset;
+ __u8 dev_uuid[BTRFS_UUID_SIZE];
+};
+
+struct btrfs_chunk_info {
+ /* logical start of this chunk */
+ __u64 offset;
+ /* size of this chunk in bytes */
+ __u64 length;
+
+ __u64 stripe_len;
+ __u64 type;
+
+ /* 2^16 stripes is quite a lot, a second limit is the size of a single
+ * item in the btree
+ */
+ __u16 num_stripes;
+
+ /* sub stripes only matter for raid10 */
+ __u16 sub_stripes;
+
+ struct btrfs_chunk_info_stripe stripes[1];
+ /* additional stripes go here */
+};
+
+
+struct btrfs_ioctl_chunk_info {
+ u64 offset; /* offset to start the search */
+ u32 buf_size; /* size of the buffer, including
+ * btrfs_ioctl_chunk_info
+ */
+ u32 items_count; /* number of items returned */
+};
+
/*
* Caller doesn't want file data in the send stream, even if the
* search of clone sources doesn't find an extent. UPDATE_EXTENT
@@ -841,5 +877,7 @@ enum btrfs_err_code {
struct btrfs_ioctl_feature_flags[3])
#define BTRFS_IOC_RM_DEV_V2 _IOW(BTRFS_IOCTL_MAGIC, 58, \
struct btrfs_ioctl_vol_args_v2)
+#define BTRFS_IOC_GET_CHUNK_INFO _IOR(BTRFS_IOCTL_MAGIC, 59, \
+ struct btrfs_ioctl_chunk_info)
#endif /* _UAPI_LINUX_BTRFS_H */
--
2.14.1
--
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