Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

Pull ext4 updates from Ted Ts'o:

 - further restructure ext4 documentation

 - fix up ext4's delayed allocation for bigalloc file systems

 - fix up some syzbot-detected races in EXT4_IOC_MOVE_EXT,
   EXT4_IOC_SWAP_BOOT, and ext4_remount

 - ... and a few other miscellaneous bugs and optimizations.

* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (21 commits)
  ext4: fix use-after-free race in ext4_remount()'s error path
  ext4: cache NULL when both default_acl and acl are NULL
  docs: promote the ext4 data structures book to top level
  docs: move ext4 administrative docs to admin-guide/
  jbd2: fix use after free in jbd2_log_do_checkpoint()
  ext4: propagate error from dquot_initialize() in EXT4_IOC_FSSETXATTR
  ext4: fix setattr project check in fssetxattr ioctl
  docs: make ext4 readme tables readable
  docs: fix ext4 documentation table formatting problems
  docs: generate a separate ext4 pdf file from the documentation
  ext4: convert fault handler to use vm_fault_t type
  ext4: initialize retries variable in ext4_da_write_inline_data_begin()
  ext4: fix EXT4_IOC_SWAP_BOOT
  ext4: fix build error when DX_DEBUG is defined
  ext4: fix argument checking in EXT4_IOC_MOVE_EXT
  ext4: fix reserved cluster accounting at page invalidation time
  ext4: adjust reserved cluster count when removing extents
  ext4: reduce reserved cluster count by number of allocated clusters
  ext4: fix reserved cluster accounting at delayed write time
  ext4: add new pending reservation mechanism
  ...

1 files changed, 18 insertions, 0 deletions

diff --git a/Documentation/filesystems/ext4/eainode.rst b/Documentation/filesystems/ext4/eainode.rst
new file mode 100644
index 000000000000..ecc0d01a0a72
--- /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.