[PATCH U-BOOT 17/26] fs: btrfs: Use btrfs_readlink() to implement __btrfs_readlink()

Qu Wenruo
2020-04-22T06:50:00Z

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 | 100 +++++++++++++++++++++++++++++------------------
2 files changed, 64 insertions(+), 37 deletions(-)

diff --git a/fs/btrfs/btrfs.h b/fs/btrfs/btrfs.h
index e561d27944fc..9057f2476526 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..df2f6590bb40 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5,8 +5,9 @@
* 2017 Marek Behun, CZ.NIC, marek.behun at 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 +84,81 @@ 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.
+ *
+ * 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;
+ printf("Extent for symlink %llu must be INLINE type\n", 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;
+ printf("Symlink %llu extent data compressed!\n", 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;
+ printf("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
--
2.26.0