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- // SPDX-License-Identifier: GPL-2.0+
- /*
- * BTRFS filesystem implementation for U-Boot
- *
- * 2017 Marek Behun, CZ.NIC, marek.behun@nic.cz
- */
- #include <linux/kernel.h>
- #include <malloc.h>
- #include <memalign.h>
- #include "btrfs.h"
- #include "disk-io.h"
- #include "volumes.h"
- /*
- * Read the content of symlink inode @ino of @root, into @target.
- * NOTE: @target will not be \0 termiated, caller should handle it properly.
- *
- * Return the number of read data.
- * Return <0 for error.
- */
- int btrfs_readlink(struct btrfs_root *root, u64 ino, char *target)
- {
- struct btrfs_path path;
- struct btrfs_key key;
- struct btrfs_file_extent_item *fi;
- int ret;
- key.objectid = ino;
- key.type = BTRFS_EXTENT_DATA_KEY;
- key.offset = 0;
- btrfs_init_path(&path);
- ret = btrfs_search_slot(NULL, root, &key, &path, 0, 0);
- if (ret < 0)
- return ret;
- if (ret > 0) {
- ret = -ENOENT;
- goto out;
- }
- fi = btrfs_item_ptr(path.nodes[0], path.slots[0],
- struct btrfs_file_extent_item);
- if (btrfs_file_extent_type(path.nodes[0], fi) !=
- BTRFS_FILE_EXTENT_INLINE) {
- ret = -EUCLEAN;
- error("Extent for symlink %llu must be INLINE type!", ino);
- goto out;
- }
- if (btrfs_file_extent_compression(path.nodes[0], fi) !=
- BTRFS_COMPRESS_NONE) {
- ret = -EUCLEAN;
- error("Extent for symlink %llu must not be compressed!", ino);
- goto out;
- }
- if (btrfs_file_extent_ram_bytes(path.nodes[0], fi) >=
- root->fs_info->sectorsize) {
- ret = -EUCLEAN;
- error("Symlink %llu extent data too large (%llu)!\n",
- ino, btrfs_file_extent_ram_bytes(path.nodes[0], fi));
- goto out;
- }
- read_extent_buffer(path.nodes[0], target,
- btrfs_file_extent_inline_start(fi),
- btrfs_file_extent_ram_bytes(path.nodes[0], fi));
- ret = btrfs_file_extent_ram_bytes(path.nodes[0], fi);
- out:
- btrfs_release_path(&path);
- return ret;
- }
- static int lookup_root_ref(struct btrfs_fs_info *fs_info,
- u64 rootid, u64 *root_ret, u64 *dir_ret)
- {
- struct btrfs_root *root = fs_info->tree_root;
- struct btrfs_root_ref *root_ref;
- struct btrfs_path path;
- struct btrfs_key key;
- int ret;
- btrfs_init_path(&path);
- key.objectid = rootid;
- key.type = BTRFS_ROOT_BACKREF_KEY;
- key.offset = (u64)-1;
- ret = btrfs_search_slot(NULL, root, &key, &path, 0, 0);
- if (ret < 0)
- return ret;
- /* Should not happen */
- if (ret == 0) {
- ret = -EUCLEAN;
- goto out;
- }
- ret = btrfs_previous_item(root, &path, rootid, BTRFS_ROOT_BACKREF_KEY);
- if (ret < 0)
- goto out;
- if (ret > 0) {
- ret = -ENOENT;
- goto out;
- }
- btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
- root_ref = btrfs_item_ptr(path.nodes[0], path.slots[0],
- struct btrfs_root_ref);
- *root_ret = key.offset;
- *dir_ret = btrfs_root_ref_dirid(path.nodes[0], root_ref);
- out:
- btrfs_release_path(&path);
- return ret;
- }
- /*
- * To get the parent inode of @ino of @root.
- *
- * @root_ret and @ino_ret will be filled.
- *
- * NOTE: This function is not reliable. It can only get one parent inode.
- * The get the proper parent inode, we need a full VFS inodes stack to
- * resolve properly.
- */
- static int get_parent_inode(struct btrfs_root *root, u64 ino,
- struct btrfs_root **root_ret, u64 *ino_ret)
- {
- struct btrfs_fs_info *fs_info = root->fs_info;
- struct btrfs_path path;
- struct btrfs_key key;
- int ret;
- if (ino == BTRFS_FIRST_FREE_OBJECTID) {
- u64 parent_root = -1;
- /* It's top level already, no more parent */
- if (root->root_key.objectid == BTRFS_FS_TREE_OBJECTID) {
- *root_ret = fs_info->fs_root;
- *ino_ret = BTRFS_FIRST_FREE_OBJECTID;
- return 0;
- }
- ret = lookup_root_ref(fs_info, root->root_key.objectid,
- &parent_root, ino_ret);
- if (ret < 0)
- return ret;
- key.objectid = parent_root;
- key.type = BTRFS_ROOT_ITEM_KEY;
- key.offset = (u64)-1;
- *root_ret = btrfs_read_fs_root(fs_info, &key);
- if (IS_ERR(*root_ret))
- return PTR_ERR(*root_ret);
- return 0;
- }
- btrfs_init_path(&path);
- key.objectid = ino;
- key.type = BTRFS_INODE_REF_KEY;
- key.offset = (u64)-1;
- ret = btrfs_search_slot(NULL, root, &key, &path, 0, 0);
- if (ret < 0)
- return ret;
- /* Should not happen */
- if (ret == 0) {
- ret = -EUCLEAN;
- goto out;
- }
- ret = btrfs_previous_item(root, &path, ino, BTRFS_INODE_REF_KEY);
- if (ret < 0)
- goto out;
- if (ret > 0) {
- ret = -ENOENT;
- goto out;
- }
- btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
- *root_ret = root;
- *ino_ret = key.offset;
- out:
- btrfs_release_path(&path);
- return ret;
- }
- static inline int next_length(const char *path)
- {
- int res = 0;
- while (*path != '\0' && *path != '/') {
- ++res;
- ++path;
- if (res > BTRFS_NAME_LEN)
- break;
- }
- return res;
- }
- static inline const char *skip_current_directories(const char *cur)
- {
- while (1) {
- if (cur[0] == '/')
- ++cur;
- else if (cur[0] == '.' && cur[1] == '/')
- cur += 2;
- else
- break;
- }
- return cur;
- }
- /*
- * Resolve one filename of @ino of @root.
- *
- * key_ret: The child key (either INODE_ITEM or ROOT_ITEM type)
- * type_ret: BTRFS_FT_* of the child inode.
- *
- * Return 0 with above members filled.
- * Return <0 for error.
- */
- static int resolve_one_filename(struct btrfs_root *root, u64 ino,
- const char *name, int namelen,
- struct btrfs_key *key_ret, u8 *type_ret)
- {
- struct btrfs_dir_item *dir_item;
- struct btrfs_path path;
- int ret = 0;
- btrfs_init_path(&path);
- dir_item = btrfs_lookup_dir_item(NULL, root, &path, ino, name,
- namelen, 0);
- if (IS_ERR(dir_item)) {
- ret = PTR_ERR(dir_item);
- goto out;
- }
- btrfs_dir_item_key_to_cpu(path.nodes[0], dir_item, key_ret);
- *type_ret = btrfs_dir_type(path.nodes[0], dir_item);
- out:
- btrfs_release_path(&path);
- return ret;
- }
- /*
- * Resolve a full path @filename. The start point is @ino of @root.
- *
- * The result will be filled into @root_ret, @ino_ret and @type_ret.
- */
- int btrfs_lookup_path(struct btrfs_root *root, u64 ino, const char *filename,
- struct btrfs_root **root_ret, u64 *ino_ret,
- u8 *type_ret, int symlink_limit)
- {
- struct btrfs_fs_info *fs_info = root->fs_info;
- struct btrfs_root *next_root;
- struct btrfs_key key;
- const char *cur = filename;
- u64 next_ino;
- u8 next_type;
- u8 type;
- int len;
- int ret = 0;
- /* If the path is absolute path, also search from fs root */
- if (*cur == '/') {
- root = fs_info->fs_root;
- ino = btrfs_root_dirid(&root->root_item);
- type = BTRFS_FT_DIR;
- }
- while (*cur != '\0') {
- cur = skip_current_directories(cur);
- len = next_length(cur);
- if (len > BTRFS_NAME_LEN) {
- error("%s: Name too long at \"%.*s\"", __func__,
- BTRFS_NAME_LEN, cur);
- return -ENAMETOOLONG;
- }
- if (len == 1 && cur[0] == '.')
- break;
- if (len == 2 && cur[0] == '.' && cur[1] == '.') {
- /* Go one level up */
- ret = get_parent_inode(root, ino, &next_root, &next_ino);
- if (ret < 0)
- return ret;
- root = next_root;
- ino = next_ino;
- goto next;
- }
- if (!*cur)
- break;
- ret = resolve_one_filename(root, ino, cur, len, &key, &type);
- if (ret < 0)
- return ret;
- if (key.type == BTRFS_ROOT_ITEM_KEY) {
- /* Child inode is a subvolume */
- next_root = btrfs_read_fs_root(fs_info, &key);
- if (IS_ERR(next_root))
- return PTR_ERR(next_root);
- root = next_root;
- ino = btrfs_root_dirid(&root->root_item);
- } else if (type == BTRFS_FT_SYMLINK && symlink_limit >= 0) {
- /* Child inode is a symlink */
- char *target;
- if (symlink_limit == 0) {
- error("%s: Too much symlinks!", __func__);
- return -EMLINK;
- }
- target = malloc(fs_info->sectorsize);
- if (!target)
- return -ENOMEM;
- ret = btrfs_readlink(root, key.objectid, target);
- if (ret < 0) {
- free(target);
- return ret;
- }
- target[ret] = '\0';
- ret = btrfs_lookup_path(root, ino, target, &next_root,
- &next_ino, &next_type,
- symlink_limit);
- if (ret < 0)
- return ret;
- root = next_root;
- ino = next_ino;
- type = next_type;
- } else {
- /* Child inode is an inode */
- ino = key.objectid;
- }
- next:
- cur += len;
- }
- if (!ret) {
- *root_ret = root;
- *ino_ret = ino;
- *type_ret = type;
- }
- return ret;
- }
- /*
- * Read out inline extent.
- *
- * Since inline extent should only exist for offset 0, no need for extra
- * parameters.
- * Truncating should be handled by the caller.
- *
- * Return the number of bytes read.
- * Return <0 for error.
- */
- int btrfs_read_extent_inline(struct btrfs_path *path,
- struct btrfs_file_extent_item *fi, char *dest)
- {
- struct extent_buffer *leaf = path->nodes[0];
- int slot = path->slots[0];
- char *cbuf = NULL;
- char *dbuf = NULL;
- u32 csize;
- u32 dsize;
- int ret;
- csize = btrfs_file_extent_inline_item_len(leaf, btrfs_item_nr(slot));
- if (btrfs_file_extent_compression(leaf, fi) == BTRFS_COMPRESS_NONE) {
- /* Uncompressed, just read it out */
- read_extent_buffer(leaf, dest,
- btrfs_file_extent_inline_start(fi),
- csize);
- return csize;
- }
- /* Compressed extent, prepare the compressed and data buffer */
- dsize = btrfs_file_extent_ram_bytes(leaf, fi);
- cbuf = malloc(csize);
- dbuf = malloc(dsize);
- if (!cbuf || !dbuf) {
- ret = -ENOMEM;
- goto out;
- }
- read_extent_buffer(leaf, cbuf, btrfs_file_extent_inline_start(fi),
- csize);
- ret = btrfs_decompress(btrfs_file_extent_compression(leaf, fi),
- cbuf, csize, dbuf, dsize);
- if (ret < 0 || ret != dsize) {
- ret = -EIO;
- goto out;
- }
- memcpy(dest, dbuf, dsize);
- ret = dsize;
- out:
- free(cbuf);
- free(dbuf);
- return ret;
- }
- /*
- * Read out regular extent.
- *
- * Truncating should be handled by the caller.
- *
- * @offset and @len should not cross the extent boundary.
- * Return the number of bytes read.
- * Return <0 for error.
- */
- int btrfs_read_extent_reg(struct btrfs_path *path,
- struct btrfs_file_extent_item *fi, u64 offset,
- int len, char *dest)
- {
- struct extent_buffer *leaf = path->nodes[0];
- struct btrfs_fs_info *fs_info = leaf->fs_info;
- struct btrfs_key key;
- u64 extent_num_bytes;
- u64 disk_bytenr;
- u64 read;
- char *cbuf = NULL;
- char *dbuf = NULL;
- u32 csize;
- u32 dsize;
- bool finished = false;
- int num_copies;
- int i;
- int slot = path->slots[0];
- int ret;
- btrfs_item_key_to_cpu(leaf, &key, slot);
- extent_num_bytes = btrfs_file_extent_num_bytes(leaf, fi);
- ASSERT(IS_ALIGNED(offset, fs_info->sectorsize) &&
- IS_ALIGNED(len, fs_info->sectorsize));
- ASSERT(offset >= key.offset &&
- offset + len <= key.offset + extent_num_bytes);
- /* Preallocated or hole , fill @dest with zero */
- if (btrfs_file_extent_type(leaf, fi) == BTRFS_FILE_EXTENT_PREALLOC ||
- btrfs_file_extent_disk_bytenr(leaf, fi) == 0) {
- memset(dest, 0, len);
- return len;
- }
- if (btrfs_file_extent_compression(leaf, fi) == BTRFS_COMPRESS_NONE) {
- u64 logical;
- logical = btrfs_file_extent_disk_bytenr(leaf, fi) +
- btrfs_file_extent_offset(leaf, fi) +
- offset - key.offset;
- read = len;
- num_copies = btrfs_num_copies(fs_info, logical, len);
- for (i = 1; i <= num_copies; i++) {
- ret = read_extent_data(fs_info, dest, logical, &read, i);
- if (ret < 0 || read != len)
- continue;
- finished = true;
- break;
- }
- if (!finished)
- return -EIO;
- return len;
- }
- csize = btrfs_file_extent_disk_num_bytes(leaf, fi);
- dsize = btrfs_file_extent_ram_bytes(leaf, fi);
- disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
- num_copies = btrfs_num_copies(fs_info, disk_bytenr, csize);
- cbuf = malloc_cache_aligned(csize);
- dbuf = malloc_cache_aligned(dsize);
- if (!cbuf || !dbuf) {
- ret = -ENOMEM;
- goto out;
- }
- /* For compressed extent, we must read the whole on-disk extent */
- for (i = 1; i <= num_copies; i++) {
- read = csize;
- ret = read_extent_data(fs_info, cbuf, disk_bytenr,
- &read, i);
- if (ret < 0 || read != csize)
- continue;
- finished = true;
- break;
- }
- if (!finished) {
- ret = -EIO;
- goto out;
- }
- ret = btrfs_decompress(btrfs_file_extent_compression(leaf, fi), cbuf,
- csize, dbuf, dsize);
- if (ret != dsize) {
- ret = -EIO;
- goto out;
- }
- /* Then copy the needed part */
- memcpy(dest, dbuf + btrfs_file_extent_offset(leaf, fi), len);
- ret = len;
- out:
- free(cbuf);
- free(dbuf);
- return ret;
- }
- /*
- * Get the first file extent that covers bytenr @file_offset.
- *
- * @file_offset must be aligned to sectorsize.
- *
- * return 0 for found, and path points to the file extent.
- * return >0 for not found, and fill @next_offset.
- * @next_offset can be 0 if there is no next file extent.
- * return <0 for error.
- */
- static int lookup_data_extent(struct btrfs_root *root, struct btrfs_path *path,
- u64 ino, u64 file_offset, u64 *next_offset)
- {
- struct btrfs_key key;
- struct btrfs_file_extent_item *fi;
- u8 extent_type;
- int ret = 0;
- ASSERT(IS_ALIGNED(file_offset, root->fs_info->sectorsize));
- key.objectid = ino;
- key.type = BTRFS_EXTENT_DATA_KEY;
- key.offset = file_offset;
- ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
- /* Error or we're already at the file extent */
- if (ret <= 0)
- return ret;
- if (ret > 0) {
- /* Check previous file extent */
- ret = btrfs_previous_item(root, path, ino,
- BTRFS_EXTENT_DATA_KEY);
- if (ret < 0)
- return ret;
- if (ret > 0)
- goto check_next;
- }
- /* Now the key.offset must be smaller than @file_offset */
- btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
- if (key.objectid != ino ||
- key.type != BTRFS_EXTENT_DATA_KEY)
- goto check_next;
- fi = btrfs_item_ptr(path->nodes[0], path->slots[0],
- struct btrfs_file_extent_item);
- extent_type = btrfs_file_extent_type(path->nodes[0], fi);
- if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
- if (file_offset == 0)
- return 0;
- /* Inline extent should be the only extent, no next extent. */
- *next_offset = 0;
- return 1;
- }
- /* This file extent covers @file_offset */
- if (key.offset <= file_offset && key.offset +
- btrfs_file_extent_num_bytes(path->nodes[0], fi) > file_offset)
- return 0;
- check_next:
- ret = btrfs_next_item(root, path);
- if (ret < 0)
- return ret;
- if (ret > 0) {
- *next_offset = 0;
- return 1;
- }
- btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
- fi = btrfs_item_ptr(path->nodes[0], path->slots[0],
- struct btrfs_file_extent_item);
- /* Next next data extent */
- if (key.objectid != ino ||
- key.type != BTRFS_EXTENT_DATA_KEY) {
- *next_offset = 0;
- return 1;
- }
- /* Current file extent already beyond @file_offset */
- if (key.offset > file_offset) {
- *next_offset = key.offset;
- return 1;
- }
- /* This file extent covers @file_offset */
- if (key.offset <= file_offset && key.offset +
- btrfs_file_extent_num_bytes(path->nodes[0], fi) > file_offset)
- return 0;
- /* This file extent ends before @file_offset, check next */
- ret = btrfs_next_item(root, path);
- if (ret < 0)
- return ret;
- if (ret > 0) {
- *next_offset = 0;
- return 1;
- }
- btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
- if (key.type != BTRFS_EXTENT_DATA_KEY || key.objectid != ino) {
- *next_offset = 0;
- return 1;
- }
- *next_offset = key.offset;
- return 1;
- }
- static int read_and_truncate_page(struct btrfs_path *path,
- struct btrfs_file_extent_item *fi,
- int start, int len, char *dest)
- {
- struct extent_buffer *leaf = path->nodes[0];
- struct btrfs_fs_info *fs_info = leaf->fs_info;
- u64 aligned_start = round_down(start, fs_info->sectorsize);
- u8 extent_type;
- char *buf;
- int page_off = start - aligned_start;
- int page_len = fs_info->sectorsize - page_off;
- int ret;
- ASSERT(start + len <= aligned_start + fs_info->sectorsize);
- buf = malloc_cache_aligned(fs_info->sectorsize);
- if (!buf)
- return -ENOMEM;
- extent_type = btrfs_file_extent_type(leaf, fi);
- if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
- ret = btrfs_read_extent_inline(path, fi, buf);
- memcpy(dest, buf + page_off, min(page_len, ret));
- free(buf);
- return len;
- }
- ret = btrfs_read_extent_reg(path, fi,
- round_down(start, fs_info->sectorsize),
- fs_info->sectorsize, buf);
- if (ret < 0) {
- free(buf);
- return ret;
- }
- memcpy(dest, buf + page_off, page_len);
- free(buf);
- return len;
- }
- int btrfs_file_read(struct btrfs_root *root, u64 ino, u64 file_offset, u64 len,
- char *dest)
- {
- struct btrfs_fs_info *fs_info = root->fs_info;
- struct btrfs_file_extent_item *fi;
- struct btrfs_path path;
- struct btrfs_key key;
- u64 aligned_start = round_down(file_offset, fs_info->sectorsize);
- u64 aligned_end = round_down(file_offset + len, fs_info->sectorsize);
- u64 next_offset;
- u64 cur = aligned_start;
- int ret = 0;
- btrfs_init_path(&path);
- /* Set the whole dest all zero, so we won't need to bother holes */
- memset(dest, 0, len);
- /* Read out the leading unaligned part */
- if (aligned_start != file_offset) {
- ret = lookup_data_extent(root, &path, ino, aligned_start,
- &next_offset);
- if (ret < 0)
- goto out;
- if (ret == 0) {
- /* Read the unaligned part out*/
- fi = btrfs_item_ptr(path.nodes[0], path.slots[0],
- struct btrfs_file_extent_item);
- ret = read_and_truncate_page(&path, fi, file_offset,
- round_up(file_offset, fs_info->sectorsize) -
- file_offset, dest);
- if (ret < 0)
- goto out;
- cur += fs_info->sectorsize;
- } else {
- /* The whole file is a hole */
- if (!next_offset) {
- memset(dest, 0, len);
- return len;
- }
- cur = next_offset;
- }
- }
- /* Read the aligned part */
- while (cur < aligned_end) {
- u64 extent_num_bytes;
- u8 type;
- btrfs_release_path(&path);
- ret = lookup_data_extent(root, &path, ino, cur, &next_offset);
- if (ret < 0)
- goto out;
- if (ret > 0) {
- /* No next, direct exit */
- if (!next_offset) {
- ret = 0;
- goto out;
- }
- }
- fi = btrfs_item_ptr(path.nodes[0], path.slots[0],
- struct btrfs_file_extent_item);
- btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
- type = btrfs_file_extent_type(path.nodes[0], fi);
- if (type == BTRFS_FILE_EXTENT_INLINE) {
- ret = btrfs_read_extent_inline(&path, fi, dest);
- goto out;
- }
- /* Skip holes, as we have zeroed the dest */
- if (type == BTRFS_FILE_EXTENT_PREALLOC ||
- btrfs_file_extent_disk_bytenr(path.nodes[0], fi) == 0) {
- cur = key.offset + btrfs_file_extent_num_bytes(
- path.nodes[0], fi);
- continue;
- }
- /* Read the remaining part of the extent */
- extent_num_bytes = btrfs_file_extent_num_bytes(path.nodes[0],
- fi);
- ret = btrfs_read_extent_reg(&path, fi, cur,
- min(extent_num_bytes, aligned_end - cur),
- dest + cur - file_offset);
- if (ret < 0)
- goto out;
- cur += min(extent_num_bytes, aligned_end - cur);
- }
- /* Read the tailing unaligned part*/
- if (file_offset + len != aligned_end) {
- btrfs_release_path(&path);
- ret = lookup_data_extent(root, &path, ino, aligned_end,
- &next_offset);
- /* <0 is error, >0 means no extent */
- if (ret)
- goto out;
- fi = btrfs_item_ptr(path.nodes[0], path.slots[0],
- struct btrfs_file_extent_item);
- ret = read_and_truncate_page(&path, fi, aligned_end,
- file_offset + len - aligned_end,
- dest + aligned_end - file_offset);
- }
- out:
- btrfs_release_path(&path);
- if (ret < 0)
- return ret;
- return len;
- }
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