unimore/kernel-hacking-2024-linux-steffo
unimore/kernel-hacking-2024-linux-steffo
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btrfs: qgroup: preallocate memory before adding a relation

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There's a transaction joined in the qgroup relation add/remove ioctl and
any error will lead to abort/error. We could lift the allocation from
btrfs_add_qgroup_relation() and move it outside of the transaction
context. The relation deletion does not need that.

The ownership of the structure is moved to the add relation handler.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
David Sterba 2024-05-22 18:17:05 +02:00
parent 7733b8dd18
commit 4addc1ffd6
3 changed files with 34 additions and 19 deletions
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17
fs/btrfs/ioctl.c
View file

@ -3829,6 +3829,7 @@ static long btrfs_ioctl_qgroup_assign(struct file *file, void __user *arg)
struct btrfs_fs_info *fs_info = inode_to_fs_info(inode);
struct btrfs_root *root = BTRFS_I(inode)->root;
struct btrfs_ioctl_qgroup_assign_args *sa;
struct btrfs_qgroup_list *prealloc = NULL;
struct btrfs_trans_handle *trans;
int ret;
int err;
@ -3849,14 +3850,27 @@ static long btrfs_ioctl_qgroup_assign(struct file *file, void __user *arg)
goto drop_write;
}
if (sa->assign) {
prealloc = kzalloc(sizeof(*prealloc), GFP_KERNEL);
if (!prealloc) {
ret = -ENOMEM;
goto drop_write;
}
}
trans = btrfs_join_transaction(root);
if (IS_ERR(trans)) {
ret = PTR_ERR(trans);
goto out;
}
/*
* Prealloc ownership is moved to the relation handler, there it's used
* or freed on error.
*/
if (sa->assign) {
ret = btrfs_add_qgroup_relation(trans, sa->src, sa->dst);
ret = btrfs_add_qgroup_relation(trans, sa->src, sa->dst, prealloc);
prealloc = NULL;
} else {
ret = btrfs_del_qgroup_relation(trans, sa->src, sa->dst);
}
@ -3873,6 +3887,7 @@ static long btrfs_ioctl_qgroup_assign(struct file *file, void __user *arg)
ret = err;
out:
kfree(prealloc);
kfree(sa);
drop_write:
mnt_drop_write_file(file);

25
fs/btrfs/qgroup.c
View file

@ -155,16 +155,6 @@ static inline u64 btrfs_qgroup_get_new_refcnt(const struct btrfs_qgroup *qg, u64
return qg->new_refcnt - seq;
}
/*
* glue structure to represent the relations between qgroups.
*/
struct btrfs_qgroup_list {
struct list_head next_group;
struct list_head next_member;
struct btrfs_qgroup *group;
struct btrfs_qgroup *member;
};
static int
qgroup_rescan_init(struct btrfs_fs_info *fs_info, u64 progress_objectid,
int init_flags);
@ -1569,15 +1559,21 @@ static int quick_update_accounting(struct btrfs_fs_info *fs_info,
return ret;
}
int btrfs_add_qgroup_relation(struct btrfs_trans_handle *trans, u64 src, u64 dst)
/*
* Add relation between @src and @dst qgroup. The @prealloc is allocated by the
* callers and transferred here (either used or freed on error).
*/
int btrfs_add_qgroup_relation(struct btrfs_trans_handle *trans, u64 src, u64 dst,
struct btrfs_qgroup_list *prealloc)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_qgroup *parent;
struct btrfs_qgroup *member;
struct btrfs_qgroup_list *list;
struct btrfs_qgroup_list *prealloc = NULL;
int ret = 0;
ASSERT(prealloc);
/* Check the level of src and dst first */
if (btrfs_qgroup_level(src) >= btrfs_qgroup_level(dst))
return -EINVAL;
@ -1602,11 +1598,6 @@ int btrfs_add_qgroup_relation(struct btrfs_trans_handle *trans, u64 src, u64 dst
}
}
prealloc = kzalloc(sizeof(*list), GFP_NOFS);
if (!prealloc) {
ret = -ENOMEM;
goto out;
}
ret = add_qgroup_relation_item(trans, src, dst);
if (ret)
goto out;

11
fs/btrfs/qgroup.h
View file

@ -278,6 +278,14 @@ struct btrfs_qgroup {
struct kobject kobj;
};
/* Glue structure to represent the relations between qgroups. */
struct btrfs_qgroup_list {
struct list_head next_group;
struct list_head next_member;
struct btrfs_qgroup *group;
struct btrfs_qgroup *member;
};
struct btrfs_squota_delta {
/* The fstree root this delta counts against. */
u64 root;
@ -321,7 +329,8 @@ int btrfs_qgroup_rescan(struct btrfs_fs_info *fs_info);
void btrfs_qgroup_rescan_resume(struct btrfs_fs_info *fs_info);
int btrfs_qgroup_wait_for_completion(struct btrfs_fs_info *fs_info,
bool interruptible);
int btrfs_add_qgroup_relation(struct btrfs_trans_handle *trans, u64 src, u64 dst);
int btrfs_add_qgroup_relation(struct btrfs_trans_handle *trans, u64 src, u64 dst,
struct btrfs_qgroup_list *prealloc);
int btrfs_del_qgroup_relation(struct btrfs_trans_handle *trans, u64 src,
u64 dst);
int btrfs_create_qgroup(struct btrfs_trans_handle *trans, u64 qgroupid);