xfs: move xfs_symlink_remote.c declarations to xfs_symlink_remote.h

Move declarations for libxfs symlink functions into a separate header
file like we do for most everything else.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

xfs: repair file modes by scanning for a dirent pointing to us

Repair might encounter an inode with a totally garbage i_mode. To fix
this problem, we have to figure out if the file was a regular file, a
directory, or a special file. One way to figure this out is to check if
there are any directories with entries pointing down to the busted file.

This patch recovers the file mode by scanning every directory entry on
the filesystem to see if there are any that point to the busted file.
If the ftype of all such dirents are consistent, the mode is recovered
from the ftype. If no dirents are found, the file becomes a regular
file. In all cases, ACLs are canceled and the file is made accessible
only by root.

A previous patch attempted to guess the mode by reading the beginning of
the file data. This was rejected by Christoph on the grounds that we
cannot trust user-controlled data blocks. Users do not have direct
control over the ondisk contents of directory entries, so this method
should be much safer.

If all the dirents have the same ftype, then we can translate that back
into an S_IFMT flag and fix the file. If not, reset the mode to
S_IFREG.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

xfs: remove struct xfs_attr_shortform

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>

xfs: zap broken inode forks

Determine if inode fork damage is responsible for the inode being unable
to pass the ifork verifiers in xfs_iget and zap the fork contents if
this is true. Once this is done the fork will be empty but we'll be
able to construct an in-core inode, and a subsequent call to the inode
fork repair ioctl will search the rmapbt to rebuild the records that
were in the fork.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

xfs: repair inode records

If an inode is so badly damaged that it cannot be loaded into the cache,
fix the ondisk metadata and try again. If there /is/ a cached inode,
fix any problems and apply any optimizations that can be solved incore.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>