On Thu, 2020-11-12 at 15:23 +0000, Luis Henriques wrote:
> This reverts commit dffdcd71458e699e839f0bf47c3d42d64210b939.
> 
> When doing a rename across quota realms, there's a corner case that isn't
> handled correctly.  Here's a testcase:
> 
>   mkdir files limit
>   truncate files/file -s 10G
>   setfattr limit -n ceph.quota.max_bytes -v 1000000
>   mv files limit/
> 
> The above will succeed because ftruncate(2) won't immediately notify the
> MDSs with the new file size, and thus the quota realms stats won't be
> updated.
> 
> Since the possible fixes for this issue would have a huge performance impact,
> the solution for now is to simply revert to returning -EXDEV when doing a 
> cross
> quota realms rename.
> 
> URL: https://tracker.ceph.com/issues/48203
> Signed-off-by: Luis Henriques <lhenriq...@suse.de>
> ---
>  fs/ceph/dir.c   |  9 ++++----
>  fs/ceph/quota.c | 58 +------------------------------------------------
>  fs/ceph/super.h |  3 +--
>  3 files changed, 6 insertions(+), 64 deletions(-)
> 
> diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
> index a4d48370b2b3..858ee7362ff5 100644
> --- a/fs/ceph/dir.c
> +++ b/fs/ceph/dir.c
> @@ -1202,12 +1202,11 @@ static int ceph_rename(struct inode *old_dir, struct 
> dentry *old_dentry,
>                       op = CEPH_MDS_OP_RENAMESNAP;
>               else
>                       return -EROFS;
> -     } else if (old_dir != new_dir) {
> -             err = ceph_quota_check_rename(mdsc, d_inode(old_dentry),
> -                                           new_dir);
> -             if (err)
> -                     return err;
>       }
> +     /* don't allow cross-quota renames */
> +     if ((old_dir != new_dir) &&
> +         (!ceph_quota_is_same_realm(old_dir, new_dir)))
> +             return -EXDEV;
>  
> 
>       dout("rename dir %p dentry %p to dir %p dentry %p\n",
>            old_dir, old_dentry, new_dir, new_dentry);
> diff --git a/fs/ceph/quota.c b/fs/ceph/quota.c
> index 9b785f11e95a..4e32c9600ecc 100644
> --- a/fs/ceph/quota.c
> +++ b/fs/ceph/quota.c
> @@ -264,7 +264,7 @@ static struct ceph_snap_realm *get_quota_realm(struct 
> ceph_mds_client *mdsc,
>       return NULL;
>  }
>  
> 
> -static bool ceph_quota_is_same_realm(struct inode *old, struct inode *new)
> +bool ceph_quota_is_same_realm(struct inode *old, struct inode *new)
>  {
>       struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(old->i_sb);
>       struct ceph_snap_realm *old_realm, *new_realm;
> @@ -516,59 +516,3 @@ bool ceph_quota_update_statfs(struct ceph_fs_client 
> *fsc, struct kstatfs *buf)
>       return is_updated;
>  }
>  
> 
> -/*
> - * ceph_quota_check_rename - check if a rename can be executed
> - * @mdsc:    MDS client instance
> - * @old:     inode to be copied
> - * @new:     destination inode (directory)
> - *
> - * This function verifies if a rename (e.g. moving a file or directory) can 
> be
> - * executed.  It forces an rstat update in the @new target directory (and in 
> the
> - * source @old as well, if it's a directory).  The actual check is done both 
> for
> - * max_files and max_bytes.
> - *
> - * This function returns 0 if it's OK to do the rename, or, if quotas are
> - * exceeded, -EXDEV (if @old is a directory) or -EDQUOT.
> - */
> -int ceph_quota_check_rename(struct ceph_mds_client *mdsc,
> -                         struct inode *old, struct inode *new)
> -{
> -     struct ceph_inode_info *ci_old = ceph_inode(old);
> -     int ret = 0;
> -
> -     if (ceph_quota_is_same_realm(old, new))
> -             return 0;
> -
> -     /*
> -      * Get the latest rstat for target directory (and for source, if a
> -      * directory)
> -      */
> -     ret = ceph_do_getattr(new, CEPH_STAT_RSTAT, false);
> -     if (ret)
> -             return ret;
> -
> -     if (S_ISDIR(old->i_mode)) {
> -             ret = ceph_do_getattr(old, CEPH_STAT_RSTAT, false);
> -             if (ret)
> -                     return ret;
> -             ret = check_quota_exceeded(new, QUOTA_CHECK_MAX_BYTES_OP,
> -                                        ci_old->i_rbytes);
> -             if (!ret)
> -                     ret = check_quota_exceeded(new,
> -                                                QUOTA_CHECK_MAX_FILES_OP,
> -                                                ci_old->i_rfiles +
> -                                                ci_old->i_rsubdirs);
> -             if (ret)
> -                     ret = -EXDEV;
> -     } else {
> -             ret = check_quota_exceeded(new, QUOTA_CHECK_MAX_BYTES_OP,
> -                                        i_size_read(old));
> -             if (!ret)
> -                     ret = check_quota_exceeded(new,
> -                                                QUOTA_CHECK_MAX_FILES_OP, 1);
> -             if (ret)
> -                     ret = -EDQUOT;
> -     }
> -
> -     return ret;
> -}
> diff --git a/fs/ceph/super.h b/fs/ceph/super.h
> index 482473e4cce1..8dbb0babddea 100644
> --- a/fs/ceph/super.h
> +++ b/fs/ceph/super.h
> @@ -1222,14 +1222,13 @@ extern void ceph_handle_quota(struct ceph_mds_client 
> *mdsc,
>                             struct ceph_mds_session *session,
>                             struct ceph_msg *msg);
>  extern bool ceph_quota_is_max_files_exceeded(struct inode *inode);
> +extern bool ceph_quota_is_same_realm(struct inode *old, struct inode *new);
>  extern bool ceph_quota_is_max_bytes_exceeded(struct inode *inode,
>                                            loff_t newlen);
>  extern bool ceph_quota_is_max_bytes_approaching(struct inode *inode,
>                                               loff_t newlen);
>  extern bool ceph_quota_update_statfs(struct ceph_fs_client *fsc,
>                                    struct kstatfs *buf);
> -extern int ceph_quota_check_rename(struct ceph_mds_client *mdsc,
> -                                struct inode *old, struct inode *new);
>  extern void ceph_cleanup_quotarealms_inodes(struct ceph_mds_client *mdsc);
>  
> 
>  #endif /* _FS_CEPH_SUPER_H */

Ok, looks reasonable for now. I'll note that we probably _could_ allow
for cross-quota renames of regular files since we know that we're only
dealing with a single inode.

That said, it might be weird to see EXDEV on a directory but not a
regular file in the same parent dir.
-- 
Jeff Layton <jlay...@kernel.org>

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