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btrfs-progs: Add fixing function for inodes whose nlink dismatch 

[BUG]
At least two users have already hit a bug in btrfs causing file
missing(Chromium config file).
The missing file's nlink is still 1 but its backref points to non-exist
parent inode.

This should be a kernel bug, but btrfsck fix is needed anyway.

[FIX]
For such nlink mismatch inode, we will reset all the inode_ref with its
dir_index/item (including valid one), and re-add the valids.
If there is no valid backref for it, create 'lost+found' under the root
of the subvolume and add link to the directory.

Reported-by: Mike Gavrilov <mikhail.v.gavrilov@gmail.com>
Reported-by: Ed Tomlinson <edt@aei.ca>
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
master
Qu Wenruo 2014-12-09 16:27:29 +08:00 committed by David Sterba
parent 15bc913158
commit 61d7fc4ee6
1 changed files with 189 additions and 4 deletions
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193
cmds-check.c
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@ -1837,6 +1837,18 @@ static int repair_inode_backrefs(struct btrfs_root *root,
struct btrfs_trans_handle *trans;
struct btrfs_key location;
ret = check_dir_conflict(root, backref->name,
backref->namelen,
backref->dir,
backref->index);
if (ret) {
/*
* let nlink fixing routine to handle it,
* which can do it better.
*/
ret = 0;
break;
}
location.objectid = rec->ino;
location.type = BTRFS_INODE_ITEM_KEY;
location.offset = 0;
@ -1915,20 +1927,191 @@ static int find_file_name(struct inode_record *rec,
return -ENOENT;
}
/* Reset the nlink of the inode to the correct one */
static int reset_nlink(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_path *path,
struct inode_record *rec)
{
struct inode_backref *backref;
struct inode_backref *tmp;
struct btrfs_key key;
struct btrfs_inode_item *inode_item;
int ret = 0;
/* Remove all backref including the valid ones */
list_for_each_entry_safe(backref, tmp, &rec->backrefs, list) {
ret = btrfs_unlink(trans, root, rec->ino, backref->dir,
backref->index, backref->name,
backref->namelen, 0);
if (ret < 0)
goto out;
/* remove invalid backref, so it won't be added back */
if (!(backref->found_dir_index &&
backref->found_dir_item &&
backref->found_inode_ref)) {
list_del(&backref->list);
free(backref);
}
}
/* Set nlink to 0 */
key.objectid = rec->ino;
key.type = BTRFS_INODE_ITEM_KEY;
key.offset = 0;
ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
if (ret < 0)
goto out;
if (ret > 0) {
ret = -ENOENT;
goto out;
}
inode_item = btrfs_item_ptr(path->nodes[0], path->slots[0],
struct btrfs_inode_item);
btrfs_set_inode_nlink(path->nodes[0], inode_item, 0);
btrfs_mark_buffer_dirty(path->nodes[0]);
btrfs_release_path(path);
/*
* Add back valid inode_ref/dir_item/dir_index,
* add_link() will handle the nlink inc, so new nlink must be correct
*/
list_for_each_entry(backref, &rec->backrefs, list) {
ret = btrfs_add_link(trans, root, rec->ino, backref->dir,
backref->name, backref->namelen,
backref->ref_type, &backref->index, 1);
if (ret < 0)
goto out;
}
out:
btrfs_release_path(path);
return ret;
}
static int repair_inode_nlinks(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_path *path,
struct inode_record *rec)
{
char *dir_name = "lost+found";
char namebuf[BTRFS_NAME_LEN] = {0};
u64 lost_found_ino;
u32 mode = 0700;
u8 type = 0;
int namelen = 0;
int name_recovered = 0;
int type_recovered = 0;
int ret = 0;
/*
* Get file name and type first before these invalid inode ref
* are deleted by remove_all_invalid_backref()
*/
name_recovered = !find_file_name(rec, namebuf, &namelen);
type_recovered = !find_file_type(rec, &type);
if (!name_recovered) {
printf("Can't get file name for inode %llu, using '%llu' as fallback\n",
rec->ino, rec->ino);
namelen = count_digits(rec->ino);
sprintf(namebuf, "%llu", rec->ino);
name_recovered = 1;
}
if (!type_recovered) {
printf("Can't get file type for inode %llu, using FILE as fallback\n",
rec->ino);
type = BTRFS_FT_REG_FILE;
type_recovered = 1;
}
ret = reset_nlink(trans, root, path, rec);
if (ret < 0) {
fprintf(stderr,
"Failed to reset nlink for inode %llu: %s\n",
rec->ino, strerror(-ret));
goto out;
}
if (rec->found_link == 0) {
lost_found_ino = root->highest_inode;
if (lost_found_ino >= BTRFS_LAST_FREE_OBJECTID) {
ret = -EOVERFLOW;
goto out;
}
lost_found_ino++;
ret = btrfs_mkdir(trans, root, dir_name, strlen(dir_name),
BTRFS_FIRST_FREE_OBJECTID, &lost_found_ino,
mode);
if (ret < 0) {
fprintf(stderr, "Failed to create '%s' dir: %s",
dir_name, strerror(-ret));
goto out;
}
ret = btrfs_add_link(trans, root, rec->ino, lost_found_ino,
namebuf, namelen, type, NULL, 1);
if (ret == -EEXIST) {
/*
* Conflicting file name, add ".INO" as suffix * +1 for '.'
*/
if (namelen + count_digits(rec->ino) + 1 >
BTRFS_NAME_LEN) {
ret = -EFBIG;
goto out;
}
snprintf(namebuf + namelen, BTRFS_NAME_LEN - namelen,
".%llu", rec->ino);
namelen += count_digits(rec->ino) + 1;
ret = btrfs_add_link(trans, root, rec->ino,
lost_found_ino, namebuf,
namelen, type, NULL, 1);
}
if (ret < 0) {
fprintf(stderr,
"Failed to link the inode %llu to %s dir: %s",
rec->ino, dir_name, strerror(-ret));
goto out;
}
/*
* Just increase the found_link, don't actually add the
* backref. This will make things easier and this inode
* record will be freed after the repair is done.
* So fsck will not report problem about this inode.
*/
rec->found_link++;
printf("Moving file '%.*s' to '%s' dir since it has no valid backref\n",
namelen, namebuf, dir_name);
}
rec->errors &= ~I_ERR_LINK_COUNT_WRONG;
printf("Fixed the nlink of inode %llu\n", rec->ino);
out:
btrfs_release_path(path);
return ret;
}
static int try_repair_inode(struct btrfs_root *root, struct inode_record *rec)
{
struct btrfs_trans_handle *trans;
struct btrfs_path *path;
int ret = 0;
if (!(rec->errors & (I_ERR_DIR_ISIZE_WRONG | I_ERR_NO_ORPHAN_ITEM)))
if (!(rec->errors & (I_ERR_DIR_ISIZE_WRONG |
I_ERR_NO_ORPHAN_ITEM |
I_ERR_LINK_COUNT_WRONG)))
return rec->errors;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
trans = btrfs_start_transaction(root, 1);
/*
* For nlink repair, it may create a dir and add link, so
* 2 for parent(256)'s dir_index and dir_item
* 2 for lost+found dir's inode_item and inode_ref
* 1 for the new inode_ref of the file
* 2 for lost+found dir's dir_index and dir_item for the file
*/
trans = btrfs_start_transaction(root, 7);
if (IS_ERR(trans)) {
btrfs_free_path(path);
return PTR_ERR(trans);
@ -1938,6 +2121,8 @@ static int try_repair_inode(struct btrfs_root *root, struct inode_record *rec)
ret = repair_inode_isize(trans, root, path, rec);
if (!ret && rec->errors & I_ERR_NO_ORPHAN_ITEM)
ret = repair_inode_orphan_item(trans, root, path, rec);
if (!ret && rec->errors & I_ERR_LINK_COUNT_WRONG)
ret = repair_inode_nlinks(trans, root, path, rec);
btrfs_commit_transaction(trans, root);
btrfs_free_path(path);
return ret;
@ -2088,6 +2273,8 @@ static int check_inode_recs(struct btrfs_root *root,
}
}
if (rec->found_link != rec->nlink)
rec->errors |= I_ERR_LINK_COUNT_WRONG;
if (repair) {
ret = try_repair_inode(root, rec);
if (ret == 0 && can_free_inode_rec(rec)) {
@ -2100,8 +2287,6 @@ static int check_inode_recs(struct btrfs_root *root,
error++;
if (!rec->found_inode_item)
rec->errors |= I_ERR_NO_INODE_ITEM;
if (rec->found_link != rec->nlink)
rec->errors |= I_ERR_LINK_COUNT_WRONG;
print_inode_error(root, rec);
list_for_each_entry(backref, &rec->backrefs, list) {
if (!backref->found_dir_item)