18c2ecf20Sopenharmony_ci.. SPDX-License-Identifier: GPL-2.0 28c2ecf20Sopenharmony_ci 38c2ecf20Sopenharmony_ciLarge Extended Attribute Values 48c2ecf20Sopenharmony_ci------------------------------- 58c2ecf20Sopenharmony_ci 68c2ecf20Sopenharmony_ciTo enable ext4 to store extended attribute values that do not fit in the 78c2ecf20Sopenharmony_ciinode or in the single extended attribute block attached to an inode, 88c2ecf20Sopenharmony_cithe EA\_INODE feature allows us to store the value in the data blocks of 98c2ecf20Sopenharmony_cia regular file inode. This “EA inode” is linked only from the extended 108c2ecf20Sopenharmony_ciattribute name index and must not appear in a directory entry. The 118c2ecf20Sopenharmony_ciinode's i\_atime field is used to store a checksum of the xattr value; 128c2ecf20Sopenharmony_ciand i\_ctime/i\_version store a 64-bit reference count, which enables 138c2ecf20Sopenharmony_cisharing of large xattr values between multiple owning inodes. For 148c2ecf20Sopenharmony_cibackward compatibility with older versions of this feature, the 158c2ecf20Sopenharmony_cii\_mtime/i\_generation *may* store a back-reference to the inode number 168c2ecf20Sopenharmony_ciand i\_generation of the **one** owning inode (in cases where the EA 178c2ecf20Sopenharmony_ciinode is not referenced by multiple inodes) to verify that the EA inode 188c2ecf20Sopenharmony_ciis the correct one being accessed. 19