Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 18 insertions, 0 deletions

diff --git a/Documentation/filesystems/ext4/ondisk/eainode.rst b/Documentation/filesystems/ext4/ondisk/eainode.rst
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+.. SPDX-License-Identifier: GPL-2.0
+
+Large Extended Attribute Values
+-------------------------------
+
+To enable ext4 to store extended attribute values that do not fit in the
+inode or in the single extended attribute block attached to an inode,
+the EA\_INODE feature allows us to store the value in the data blocks of
+a regular file inode. This “EA inode” is linked only from the extended
+attribute name index and must not appear in a directory entry. The
+inode's i\_atime field is used to store a checksum of the xattr value;
+and i\_ctime/i\_version store a 64-bit reference count, which enables
+sharing of large xattr values between multiple owning inodes. For
+backward compatibility with older versions of this feature, the
+i\_mtime/i\_generation *may* store a back-reference to the inode number
+and i\_generation of the **one** owning inode (in cases where the EA
+inode is not referenced by multiple inodes) to verify that the EA inode
+is the correct one being accessed.