Shulou(Shulou.com)05/31 Report--

This article mainly introduces the cephfs kernel client for dentry operation code, has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, the following let Xiaobian take you to understand.

Operation of cephfs kernel client against dentry

Const struct dentry_operations ceph_dentry_ops = {

.d _ revalidate = ceph_d_revalidate

.d _ release = ceph_d_release

.d _ prune = ceph_d_prune

}

Ceph_d_revalidate (struct dentry * dentry, unsigned int flags) is used to check whether the dentry in cache is valid.

| | _ _ call the dget_parent () function to get the parent dentry corresponding to dentry |

| | _ _ call the d_inode () function to get the struct inode data corresponding to parent dentry |

| | _ _ call the dentry_lease_is_valid () function to check whether dentry lease is valid |

| | _ _ if invalid |

| | _ _ get the opcode op=CEPH_MDS_OP_LOOKUPSNAP or CEPH_MDS_OP_LOOKUP |

| | _ _ call the ceph_mdsc_create_request () function to create a mds request |

| | _ _ call the ceph_mdsc_do_request () function to send the request to the mds process synchronously |

| | _ _ call ceph_dentry_lru_touch () function to add dentry to lru |

Ceph_d_release (struct dentry * dentry) is called when dentry is released

| | _ _ call ceph_dentry () function to get struct ceph_dentry_info data structure |

| | _ _ call ceph_dentry_lru_del () function to delete dentry from lru |

| | _ _ set dentry- > d_fsdata=NULL |

| | _ _ call ceph_put_mds_session () function to release lease session |

| | _ _ call the kmem_cache_free () function to release the struct ceph_dentry_info data structure from cache |

Ceph_d_prune (struct dentry * dentry) calls this function when vfs removes dentry from cache

| | _ _ call the IS_ROOT () function to check whether dentry contains a valid parent, and return it directly if dentry is root |

| | _ _ call the d_unhashed () function to check whether dentry is not hashed, and return it directly (no hashed dentry is affected) |

| | _ _ call the ceph_dir_clear_complete () function to reduce the reference count of i_release_count in the struct inode of dentry- > parent |

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