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fs: btrfs: Use btrfs_readlink() to implement __btrfs_readlink()

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The existing __btrfs_readlink() can be easily re-implemented using the
extent buffer based btrfs_readlink().

This is the first step to re-implement U-Boot's btrfs code.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Marek Behún <marek.behun@nic.cz>
This commit is contained in:
Qu Wenruo 2020-06-24 18:03:03 +02:00 committed by Tom Rini
parent cafffc50ad
commit 92bc179c5f
2 changed files with 71 additions and 43 deletions
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1
fs/btrfs/btrfs.h
View file

@ -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 *);

113
fs/btrfs/inode.c
View file

@ -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))
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;
}
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;
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);
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);
goto out;
} else if (extent->encryption != 0) {
printf("%s: Symlink %llu extent data encrypted!\n", __func__,
inr);
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);
goto out;
}
data_ptr = (const char *) extent
+ offsetof(struct btrfs_file_extent_item, disk_bytenr);
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