1*4882a593Smuzhiyun.. SPDX-License-Identifier: GPL-2.0 2*4882a593Smuzhiyun 3*4882a593SmuzhiyunLarge Extended Attribute Values 4*4882a593Smuzhiyun------------------------------- 5*4882a593Smuzhiyun 6*4882a593SmuzhiyunTo enable ext4 to store extended attribute values that do not fit in the 7*4882a593Smuzhiyuninode or in the single extended attribute block attached to an inode, 8*4882a593Smuzhiyunthe EA\_INODE feature allows us to store the value in the data blocks of 9*4882a593Smuzhiyuna regular file inode. This “EA inode” is linked only from the extended 10*4882a593Smuzhiyunattribute name index and must not appear in a directory entry. The 11*4882a593Smuzhiyuninode's i\_atime field is used to store a checksum of the xattr value; 12*4882a593Smuzhiyunand i\_ctime/i\_version store a 64-bit reference count, which enables 13*4882a593Smuzhiyunsharing of large xattr values between multiple owning inodes. For 14*4882a593Smuzhiyunbackward compatibility with older versions of this feature, the 15*4882a593Smuzhiyuni\_mtime/i\_generation *may* store a back-reference to the inode number 16*4882a593Smuzhiyunand i\_generation of the **one** owning inode (in cases where the EA 17*4882a593Smuzhiyuninode is not referenced by multiple inodes) to verify that the EA inode 18*4882a593Smuzhiyunis the correct one being accessed. 19