From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Mon, 21 Sep 2026 18:24:42 +0800 Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes Skip the xarray reservation loop when clearing all memory attributes, as storing NULL only erases the entry and never needs to allocate, so no reservation (and no cleanup of a failed one) is required in that case. Suggested-by: Sean Christopherson Cc: David Ballesteros Signed-off-by: Zeng Chi Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson --- Documentation/filesystems/ext4/eainode.rst | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) create mode 100644 Documentation/filesystems/ext4/eainode.rst (limited to 'Documentation/filesystems/ext4/eainode.rst') diff --git a/Documentation/filesystems/ext4/eainode.rst b/Documentation/filesystems/ext4/eainode.rst new file mode 100644 index 000000000..7a2ef26b0 --- /dev/null +++ b/Documentation/filesystems/ext4/eainode.rst @@ -0,0 +1,18 @@ +.. 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. -- cgit v1.3.1