The existing __btrfs_readlink() can be easily re-implemented using the extent buffer based btrfs_readlink().
This should be the first step to re-implement u-boot btrfs code.
Signed-off-by: Qu Wenruo wqu@suse.com --- fs/btrfs/btrfs.h | 1 + fs/btrfs/inode.c | 101 ++++++++++++++++++++++++++++++----------------- 2 files changed, 65 insertions(+), 37 deletions(-)
diff --git a/fs/btrfs/btrfs.h b/fs/btrfs/btrfs.h index e8197391a232..53d53f310bdc 100644 --- a/fs/btrfs/btrfs.h +++ b/fs/btrfs/btrfs.h @@ -60,6 +60,7 @@ u64 __btrfs_lookup_inode_ref(struct __btrfs_root *, u64, struct btrfs_inode_ref int __btrfs_lookup_inode(const struct __btrfs_root *, struct btrfs_key *, struct btrfs_inode_item *, struct __btrfs_root *); int __btrfs_readlink(const struct __btrfs_root *, u64, char *); +int btrfs_readlink(struct btrfs_root *root, u64 ino, char *target); u64 __btrfs_lookup_path(struct __btrfs_root *, u64, const char *, u8 *, struct btrfs_inode_item *, int); u64 btrfs_file_read(const struct __btrfs_root *, u64, u64, u64, char *); diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index eb34f546b57f..007cf32c1603 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -5,8 +5,9 @@ * 2017 Marek Behun, CZ.NIC, marek.behun@nic.cz */
-#include "btrfs.h" #include <malloc.h> +#include "btrfs.h" +#include "disk-io.h"
u64 __btrfs_lookup_inode_ref(struct __btrfs_root *root, u64 inr, struct btrfs_inode_ref *refp, char *name) @@ -83,56 +84,82 @@ out: return res; }
-int __btrfs_readlink(const struct __btrfs_root *root, u64 inr, char *target) +/* + * 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_path path; struct btrfs_key key; - struct btrfs_file_extent_item *extent; - const char *data_ptr; - int res = -1; + struct btrfs_file_extent_item *fi; + int ret;
- key.objectid = inr; + key.objectid = ino; key.type = BTRFS_EXTENT_DATA_KEY; key.offset = 0; + btrfs_init_path(&path);
- if (btrfs_search_tree(root, &key, &path)) - return -1; - - if (__btrfs_comp_keys(&key, btrfs_path_leaf_key(&path))) - goto out; - - extent = btrfs_path_item_ptr(&path, struct btrfs_file_extent_item); - if (extent->type != BTRFS_FILE_EXTENT_INLINE) { - printf("%s: Extent for symlink %llu not of INLINE type\n", - __func__, inr); + ret = btrfs_search_slot(NULL, root, &key, &path, 0, 0); + if (ret < 0) + return ret; + if (ret > 0) { + ret = -ENOENT; goto out; } - - btrfs_file_extent_item_to_cpu_inl(extent); - - if (extent->compression != BTRFS_COMPRESS_NONE) { - printf("%s: Symlink %llu extent data compressed!\n", __func__, - inr); + 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; - } else if (extent->encryption != 0) { - printf("%s: Symlink %llu extent data encrypted!\n", __func__, - inr); + } + 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; - } else if (extent->ram_bytes >= btrfs_info.sb.sectorsize) { - printf("%s: Symlink %llu extent data too long (%llu)!\n", - __func__, inr, extent->ram_bytes); + } + 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; +}
- data_ptr = (const char *) extent - + offsetof(struct btrfs_file_extent_item, disk_bytenr); +int __btrfs_readlink(const struct __btrfs_root *root, u64 inr, char *target) +{ + struct btrfs_root *subvolume; + struct btrfs_fs_info *fs_info = current_fs_info; + struct btrfs_key key; + int ret; + + ASSERT(fs_info); + key.objectid = root->objectid; + key.type = BTRFS_ROOT_ITEM_KEY; + key.offset = (u64)-1; + subvolume = btrfs_read_fs_root(fs_info, &key); + if (IS_ERR(subvolume)) + return -1;
- memcpy(target, data_ptr, extent->ram_bytes); - target[extent->ram_bytes] = '\0'; - res = 0; -out: - __btrfs_free_path(&path); - return res; + ret = btrfs_readlink(subvolume, inr, target); + if (ret < 0) + return -1; + target[ret] = '\0'; + return 0; }
/* inr must be a directory (for regular files with multiple hard links this