This patch adds a pair of new file ioctls to retrieve the parent pointer
of a given inode. They both return the same results, but one operates
on the file descriptor passed to ioctl() whereas the other allows the
caller to specify a file handle for which the caller wants results.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
We need to define the parent pointer attribute format before we start
adding support for it into all the code that needs to use it. The EA
format we will use encodes the following information:
name={dirent name}
value={parent inumber, parent inode generation}
hash=xfs_dir2_hashname(dirent name) ^ (parent_inumber)
The inode/gen gives all the information we need to reliably identify the
parent without requiring child->parent lock ordering, and allows
userspace to do pathname component level reconstruction without the
kernel ever needing to verify the parent itself as part of ioctl calls.
By using the name-value lookup mode in the extended attribute code to
match parent pointers using both the xattr name and value, we can
identify the exact parent pointer EA we need to modify/remove in
rename/unlink operations without searching the entire EA space.
By storing the dirent name, we have enough information to be able to
validate and reconstruct damaged directory trees. Earlier iterations of
this patchset encoded the directory offset in the parent pointer key,
but this format required repair to keep that in sync across directory
rebuilds, which is unnecessary complexity.
Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
sparse complains about struct xfs_attr_shortform because it embeds a
structure with a variable sized array in a variable sized array.
Given that xfs_attr_shortform is not a very useful structure, and the
dir2 equivalent has been removed a long time ago, remove it as well.
Provide a xfs_attr_sf_firstentry helper that returns the first
xfs_attr_sf_entry behind a xfs_attr_sf_hdr to replace the structure
dereference.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
Move xfs_ondisk.h to libxfs so that we can do the struct sanity checks
in userspace libxfs as well. This should allow us to retire the
somewhat fragile xfs/122 test on xfstests.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
