1 .. SPDX-License-Identifier: GPL-2.0 2 3 Large Extended Attribute Values 4 ------------------------------- 5 6 To enable ext4 to store extended attribute values that do not fit in the 7 inode or in the single extended attribute block attached to an inode, 8 the EA_INODE feature allows us to store the value in the data blocks of 9 a regular file inode. This “EA inode” is linked only from the extended 10 attribute name index and must not appear in a directory entry. The 11 inode's i_atime field is used to store a checksum of the xattr value; 12 and i_ctime/i_version store a 64-bit reference count, which enables 13 sharing of large xattr values between multiple owning inodes. For 14 backward compatibility with older versions of this feature, the 15 i_mtime/i_generation *may* store a back-reference to the inode number 16 and i_generation of the **one** owning inode (in cases where the EA 17 inode is not referenced by multiple inodes) to verify that the EA inode 18 is the correct one being accessed.
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