[PATCH U-BOOT 19/26] fs: btrfs: Use btrfs_iter_dir() to replace btrfs_readdir()

Qu Wenruo
2020-04-22T06:50:02Z

Use extent buffer based infrastructure to re-implement btrfs_readdir().

Along this rework, some small corner cases fixed:
- Subvolume tree mtime
Mtime of a subvolume tree is recorded in its root item, since there is
no INODE_ITEM for it.
This needs extra search from tree root.

- Output the unknown type
If the DIR_ITEM is corrupted, at least don't try to access the memory
out of bounday.

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
fs/btrfs/btrfs.c | 157 +++++++++++++++++++++++++++-----------------
fs/btrfs/btrfs.h | 5 --
fs/btrfs/ctree.h | 5 ++
fs/btrfs/dir-item.c | 68 +++++++++++--------
4 files changed, 144 insertions(+), 91 deletions(-)

diff --git a/fs/btrfs/btrfs.c b/fs/btrfs/btrfs.c
index 7e6c7a26e4cf..e7c7ddcfc551 100644
--- a/fs/btrfs/btrfs.c
+++ b/fs/btrfs/btrfs.c
@@ -15,67 +15,102 @@
struct btrfs_info btrfs_info;
struct btrfs_fs_info *current_fs_info;

-static int readdir_callback(const struct __btrfs_root *root,
- struct btrfs_dir_item *item)
+static int show_dir(struct btrfs_root *root, struct extent_buffer *eb,
+ struct btrfs_dir_item *di)
{
- static const char typestr[BTRFS_FT_MAX][4] = {
- [BTRFS_FT_UNKNOWN] = " ? ",
- [BTRFS_FT_REG_FILE] = " ",
- [BTRFS_FT_DIR] = "DIR",
- [BTRFS_FT_CHRDEV] = "CHR",
- [BTRFS_FT_BLKDEV] = "BLK",
- [BTRFS_FT_FIFO] = "FIF",
- [BTRFS_FT_SOCK] = "SCK",
- [BTRFS_FT_SYMLINK] = "SYM",
- [BTRFS_FT_XATTR] = " ? ",
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ struct btrfs_inode_item ii;
+ struct btrfs_key key;
+ static const char* dir_item_str[] = {
+ [BTRFS_FT_REG_FILE] = "FILE",
+ [BTRFS_FT_DIR] = "DIR",
+ [BTRFS_FT_CHRDEV] = "CHRDEV",
+ [BTRFS_FT_BLKDEV] = "BLKDEV",
+ [BTRFS_FT_FIFO] = "FIFO",
+ [BTRFS_FT_SOCK] = "SOCK",
+ [BTRFS_FT_SYMLINK] = "SYMLINK",
+ [BTRFS_FT_XATTR] = "XATTR"
};
- struct btrfs_inode_item inode;
- const char *name = (const char *) (item + 1);
- char filetime[32], *target = NULL;
+ u8 type = btrfs_dir_type(eb, di);
+ char namebuf[BTRFS_NAME_LEN];
+ char *target = NULL;
+ char filetime[32];
time_t mtime;
+ int ret;

- if (__btrfs_lookup_inode(root, (struct btrfs_key *)&item->location,
- &inode, NULL)) {
- printf("%s: Cannot find inode item for directory entry %.*s!\n",
- __func__, item->name_len, name);
- return 0;
- }
-
- mtime = inode.mtime.sec;
- ctime_r(&mtime, filetime);
+ btrfs_dir_item_key_to_cpu(eb, di, &key);

- if (item->type == BTRFS_FT_SYMLINK) {
- target = malloc(min(inode.size + 1,
- (u64) btrfs_info.sb.sectorsize));
+ if (key.type == BTRFS_ROOT_ITEM_KEY) {
+ struct btrfs_root *subvol;

- if (target && __btrfs_readlink(root, item->location.objectid,
- target)) {
- free(target);
- target = NULL;
+ /* It's a subvolume, get its mtime from root item */
+ subvol = btrfs_read_fs_root(fs_info, &key);
+ if (IS_ERR(subvol)) {
+ ret = PTR_ERR(subvol);
+ error("Can't find root %llu", key.objectid);
+ return ret;
}
+ mtime = btrfs_stack_timespec_sec(&subvol->root_item.otime);
+ } else {
+ struct btrfs_path path;
+
+ /* It's regular inode, get its mtime from inode item */
+ btrfs_init_path(&path);
+ ret = btrfs_search_slot(NULL, root, &key, &path, 0, 0);
+ if (ret > 0)
+ ret = -ENOENT;
+ if (ret < 0) {
+ error("Can't find inode %llu", key.objectid);
+ btrfs_release_path(&path);
+ return ret;
+ }
+ read_extent_buffer(path.nodes[0], &ii,
+ btrfs_item_ptr_offset(path.nodes[0], path.slots[0]),
+ sizeof(ii));
+ btrfs_release_path(&path);
+ mtime = btrfs_stack_timespec_sec(&ii.mtime);
+ }
+ ctime_r(&mtime, filetime);

- if (!target)
- printf("%s: Cannot read symlink target!\n", __func__);
+ if (type == BTRFS_FT_SYMLINK) {
+ target = malloc(fs_info->sectorsize);
+ if (!target) {
+ error("Can't alloc memory for symlink %llu",
+ key.objectid);
+ return -ENOMEM;
+ }
+ ret = btrfs_readlink(root, key.objectid, target);
+ if (ret < 0) {
+ error("Failed to read symlink %llu", key.objectid);
+ goto out;
+ }
+ target[ret] = '\0';
}

- printf("<%s> ", typestr[item->type]);
- if (item->type == BTRFS_FT_CHRDEV || item->type == BTRFS_FT_BLKDEV)
- printf("%4u,%5u ", (unsigned int) (inode.rdev >> 20),
- (unsigned int) (inode.rdev & 0xfffff));
+ if (type < ARRAY_SIZE(dir_item_str) && dir_item_str[type])
+ printf("<%s> ", dir_item_str[type]);
else
- printf("%10llu ", inode.size);
-
- printf("%24.24s %.*s", filetime, item->name_len, name);
-
- if (item->type == BTRFS_FT_SYMLINK) {
- printf(" -> %s", target ? target : "?");
- if (target)
- free(target);
+ printf("DIR_ITEM.%u", type);
+ if (type == BTRFS_FT_CHRDEV || type == BTRFS_FT_BLKDEV) {
+ ASSERT(key.type == BTRFS_INODE_ITEM_KEY);
+ printf("%4llu,%5llu ", btrfs_stack_inode_rdev(&ii) >> 20,
+ btrfs_stack_inode_rdev(&ii) & 0xfffff);
+ } else {
+ if (key.type == BTRFS_INODE_ITEM_KEY)
+ printf("%10llu ", btrfs_stack_inode_size(&ii));
+ else
+ printf("%10llu ", 0ULL);
}

+ read_extent_buffer(eb, namebuf, (unsigned long)(di + 1),
+ btrfs_dir_name_len(eb, di));
+ printf("%24.24s %.*s", filetime, btrfs_dir_name_len(eb, di), namebuf);
+ if (type == BTRFS_FT_SYMLINK)
+ printf(" -> %s", target ? target : "?");
printf("\n");
-
- return 0;
+out:
+ free(target);
+ return ret;
}

int btrfs_probe(struct blk_desc *fs_dev_desc, disk_partition_t *fs_partition)
@@ -123,27 +158,29 @@ int btrfs_probe(struct blk_desc *fs_dev_desc, disk_partition_t *fs_partition)

int btrfs_ls(const char *path)
{
- struct __btrfs_root root = btrfs_info.fs_root;
- u64 inr;
+ struct btrfs_fs_info *fs_info = current_fs_info;
+ struct btrfs_root *root = fs_info->fs_root;
+ u64 ino = BTRFS_FIRST_FREE_OBJECTID;
u8 type;
+ int ret;

- inr = __btrfs_lookup_path(&root, root.root_dirid, path, &type, NULL, 40);
-
- if (inr == -1ULL) {
+ ASSERT(fs_info);
+ ret = btrfs_lookup_path(fs_info->fs_root, BTRFS_FIRST_FREE_OBJECTID,
+ path, &root, &ino, &type, 40);
+ if (ret < 0) {
printf("Cannot lookup path %s\n", path);
- return -1;
+ return ret;
}

if (type != BTRFS_FT_DIR) {
- printf("Not a directory: %s\n", path);
- return -1;
+ error("Not a directory: %s", path);
+ return -ENOENT;
}
-
- if (btrfs_readdir(&root, inr, readdir_callback)) {
- printf("An error occured while listing directory %s\n", path);
- return -1;
+ ret = btrfs_iter_dir(root, ino, show_dir);
+ if (ret < 0) {
+ error("An error occured while listing directory %s", path);
+ return ret;
}
-
return 0;
}

diff --git a/fs/btrfs/btrfs.h b/fs/btrfs/btrfs.h
index 9057f2476526..eb32eb2006a8 100644
--- a/fs/btrfs/btrfs.h
+++ b/fs/btrfs/btrfs.h
@@ -43,13 +43,8 @@ u32 btrfs_decompress(u8 type, const char *, u32, char *, u32);
int btrfs_read_superblock(void);

/* dir-item.c */
-typedef int (*btrfs_readdir_callback_t)(const struct __btrfs_root *,
- struct btrfs_dir_item *);
-
int __btrfs_lookup_dir_item(const struct __btrfs_root *, u64, const char *, int,
struct btrfs_dir_item *);
-int btrfs_readdir(const struct __btrfs_root *, u64, btrfs_readdir_callback_t);
-
/* root.c */
int btrfs_find_root(u64, struct __btrfs_root *, struct btrfs_root_item *);
u64 btrfs_lookup_root_ref(u64, struct btrfs_root_ref *, char *);
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 78f7746d1f32..fe6966e896a1 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1284,6 +1284,11 @@ struct btrfs_dir_item *btrfs_lookup_dir_item(struct btrfs_trans_handle *trans,
struct btrfs_path *path, u64 dir,
const char *name, int name_len,
int mod);
+typedef int (*btrfs_iter_dir_callback_t)(struct btrfs_root *root,
+ struct extent_buffer *eb,
+ struct btrfs_dir_item *di);
+int btrfs_iter_dir(struct btrfs_root *root, u64 ino,
+ btrfs_iter_dir_callback_t callback);
/* inode.c */
int btrfs_lookup_path(struct btrfs_root *root, u64 ino, const char *filename,
struct btrfs_root **root_ret, u64 *ino_ret,
diff --git a/fs/btrfs/dir-item.c b/fs/btrfs/dir-item.c
index 4bf45c2fa925..a6c66a021896 100644
--- a/fs/btrfs/dir-item.c
+++ b/fs/btrfs/dir-item.c
@@ -193,39 +193,55 @@ out:
return res ? 0 : -1;
}

-int btrfs_readdir(const struct __btrfs_root *root, u64 dir,
- btrfs_readdir_callback_t callback)
+int btrfs_iter_dir(struct btrfs_root *root, u64 ino,
+ btrfs_iter_dir_callback_t callback)
{
- struct __btrfs_path path;
- struct btrfs_key key, *found_key;
- struct btrfs_dir_item *item;
- int res = 0;
+ struct btrfs_path path;
+ struct btrfs_key key;
+ int ret;

- key.objectid = dir;
+ btrfs_init_path(&path);
+ key.objectid = ino;
key.type = BTRFS_DIR_INDEX_KEY;
key.offset = 0;

- if (btrfs_search_tree(root, &key, &path))
- return -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;
+ }
+ if (path.slots[0] >= btrfs_header_nritems(path.nodes[0])) {
+ ret = btrfs_next_leaf(root, &path);
+ if (ret < 0)
+ goto out;
+ if (ret > 0) {
+ ret = 0;
+ goto out;
+ }
+ }
do {
- found_key = btrfs_path_leaf_key(&path);
- if (btrfs_comp_keys_type(&key, found_key))
- break;
-
- item = btrfs_path_item_ptr(&path, struct btrfs_dir_item);
- btrfs_dir_item_to_cpu(item);
+ struct btrfs_dir_item *di;

- if (__verify_dir_item(item, 0, sizeof(*item) + item->name_len))
- continue;
- if (item->type == BTRFS_FT_XATTR)
- continue;
-
- if (callback(root, item))
+ btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
+ if (key.objectid != ino || key.type != BTRFS_DIR_INDEX_KEY)
break;
- } while (!(res = btrfs_next_slot(&path)));
-
- __btrfs_free_path(&path);
+ di = btrfs_item_ptr(path.nodes[0], path.slots[0],
+ struct btrfs_dir_item);
+ if (verify_dir_item(root, path.nodes[0], di)) {
+ ret = -EUCLEAN;
+ goto out;
+ }
+ ret = callback(root, path.nodes[0], di);
+ if (ret < 0)
+ goto out;
+ } while (!(ret = btrfs_next_item(root, &path)));

- return res < 0 ? -1 : 0;
+ if (ret > 0)
+ ret = 0;
+out:
+ btrfs_release_path(&path);
+ return ret;
}
--
2.26.0