Commit 0d29a20f authored by Darrick J. Wong's avatar Darrick J. Wong
Browse files

xfs: scrub parent pointers 



Actually check parent pointers now.

Signed-off-by: default avatarDarrick J. Wong <djwong@kernel.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
parent b961c8bf

fs/xfs/scrub/parent.c

+371 −0
Original line number Diff line number Diff line
@@ -15,11 +15,15 @@ 
#include "xfs_icache.h"

#include "xfs_dir2.h"

#include "xfs_dir2_priv.h"

#include "xfs_attr.h"

#include "xfs_parent.h"

#include "scrub/scrub.h"

#include "scrub/common.h"

#include "scrub/readdir.h"

#include "scrub/tempfile.h"

#include "scrub/repair.h"

#include "scrub/listxattr.h"

#include "scrub/trace.h"



/* Set us up to scrub parents. */

int
@@ -197,6 +201,370 @@ xchk_parent_validate( 
	return error;

}



/*

 * Checking of Parent Pointers

 * ===========================

 *

 * On filesystems with directory parent pointers, we check the referential

 * integrity by visiting each parent pointer of a child file and checking that

 * the directory referenced by the pointer actually has a dirent pointing

 * forward to the child file.

 */



struct xchk_pptrs {

	struct xfs_scrub	*sc;



	/* How many parent pointers did we find at the end? */

	unsigned long long	pptrs_found;



	/* Parent of this directory. */

	xfs_ino_t		parent_ino;

};



/* Does this parent pointer match the dotdot entry? */

STATIC int

xchk_parent_scan_dotdot(

	struct xfs_scrub		*sc,

	struct xfs_inode		*ip,

	unsigned int			attr_flags,

	const unsigned char		*name,

	unsigned int			namelen,

	const void			*value,

	unsigned int			valuelen,

	void				*priv)

{

	struct xchk_pptrs		*pp = priv;

	xfs_ino_t			parent_ino;

	int				error;



	if (!(attr_flags & XFS_ATTR_PARENT))

		return 0;



	error = xfs_parent_from_attr(sc->mp, attr_flags, name, namelen, value,

			valuelen, &parent_ino, NULL);

	if (error)

		return error;



	if (pp->parent_ino == parent_ino)

		return -ECANCELED;



	return 0;

}



/* Look up the dotdot entry so that we can check it as we walk the pptrs. */

STATIC int

xchk_parent_pptr_and_dotdot(

	struct xchk_pptrs	*pp)

{

	struct xfs_scrub	*sc = pp->sc;

	int			error;



	/* Look up '..' */

	error = xchk_dir_lookup(sc, sc->ip, &xfs_name_dotdot, &pp->parent_ino);

	if (!xchk_fblock_process_error(sc, XFS_DATA_FORK, 0, &error))

		return error;

	if (!xfs_verify_dir_ino(sc->mp, pp->parent_ino)) {

		xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, 0);

		return 0;

	}



	/* Is this the root dir?  Then '..' must point to itself. */

	if (sc->ip == sc->mp->m_rootip) {

		if (sc->ip->i_ino != pp->parent_ino)

			xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, 0);

		return 0;

	}



	/*

	 * If this is now an unlinked directory, the dotdot value is

	 * meaningless as long as it points to a valid inode.

	 */

	if (VFS_I(sc->ip)->i_nlink == 0)

		return 0;



	if (pp->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)

		return 0;



	/* Otherwise, walk the pptrs again, and check. */

	error = xchk_xattr_walk(sc, sc->ip, xchk_parent_scan_dotdot, pp);

	if (error == -ECANCELED) {

		/* Found a parent pointer that matches dotdot. */

		return 0;

	}

	if (!error || error == -EFSCORRUPTED) {

		/* Found a broken parent pointer or no match. */

		xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, 0);

		return 0;

	}

	return error;

}



/*

 * Try to lock a parent directory for checking dirents.  Returns the inode

 * flags for the locks we now hold, or zero if we failed.

 */

STATIC unsigned int

xchk_parent_lock_dir(

	struct xfs_scrub	*sc,

	struct xfs_inode	*dp)

{

	if (!xfs_ilock_nowait(dp, XFS_IOLOCK_SHARED))

		return 0;



	if (!xfs_ilock_nowait(dp, XFS_ILOCK_SHARED)) {

		xfs_iunlock(dp, XFS_IOLOCK_SHARED);

		return 0;

	}



	if (!xfs_need_iread_extents(&dp->i_df))

		return XFS_IOLOCK_SHARED | XFS_ILOCK_SHARED;



	xfs_iunlock(dp, XFS_ILOCK_SHARED);



	if (!xfs_ilock_nowait(dp, XFS_ILOCK_EXCL)) {

		xfs_iunlock(dp, XFS_IOLOCK_SHARED);

		return 0;

	}



	return XFS_IOLOCK_SHARED | XFS_ILOCK_EXCL;

}



/* Check the forward link (dirent) associated with this parent pointer. */

STATIC int

xchk_parent_dirent(

	struct xchk_pptrs	*pp,

	const struct xfs_name	*xname,

	struct xfs_inode	*dp)

{

	struct xfs_scrub	*sc = pp->sc;

	xfs_ino_t		child_ino;

	int			error;



	/*

	 * Use the name attached to this parent pointer to look up the

	 * directory entry in the alleged parent.

	 */

	error = xchk_dir_lookup(sc, dp, xname, &child_ino);

	if (error == -ENOENT) {

		xchk_fblock_xref_set_corrupt(sc, XFS_ATTR_FORK, 0);

		return 0;

	}

	if (!xchk_fblock_xref_process_error(sc, XFS_ATTR_FORK, 0, &error))

		return error;



	/* Does the inode number match? */

	if (child_ino != sc->ip->i_ino) {

		xchk_fblock_xref_set_corrupt(sc, XFS_ATTR_FORK, 0);

		return 0;

	}



	return 0;

}



/* Try to grab a parent directory. */

STATIC int

xchk_parent_iget(

	struct xchk_pptrs	*pp,

	const struct xfs_parent_rec	*pptr,

	struct xfs_inode	**dpp)

{

	struct xfs_scrub	*sc = pp->sc;

	struct xfs_inode	*ip;

	xfs_ino_t		parent_ino = be64_to_cpu(pptr->p_ino);

	int			error;



	/* Validate inode number. */

	error = xfs_dir_ino_validate(sc->mp, parent_ino);

	if (error) {

		xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, 0);

		return -ECANCELED;

	}



	error = xchk_iget(sc, parent_ino, &ip);

	if (error == -EINVAL || error == -ENOENT) {

		xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, 0);

		return -ECANCELED;

	}

	if (!xchk_fblock_xref_process_error(sc, XFS_ATTR_FORK, 0, &error))

		return error;



	/* The parent must be a directory. */

	if (!S_ISDIR(VFS_I(ip)->i_mode)) {

		xchk_fblock_xref_set_corrupt(sc, XFS_ATTR_FORK, 0);

		goto out_rele;

	}



	/* Validate generation number. */

	if (VFS_I(ip)->i_generation != be32_to_cpu(pptr->p_gen)) {

		xchk_fblock_xref_set_corrupt(sc, XFS_ATTR_FORK, 0);

		goto out_rele;

	}



	*dpp = ip;

	return 0;

out_rele:

	xchk_irele(sc, ip);

	return 0;

}



/*

 * Walk an xattr of a file.  If this xattr is a parent pointer, follow it up

 * to a parent directory and check that the parent has a dirent pointing back

 * to us.

 */

STATIC int

xchk_parent_scan_attr(

	struct xfs_scrub	*sc,

	struct xfs_inode	*ip,

	unsigned int		attr_flags,

	const unsigned char	*name,

	unsigned int		namelen,

	const void		*value,

	unsigned int		valuelen,

	void			*priv)

{

	struct xfs_name		xname = {

		.name		= name,

		.len		= namelen,

	};

	struct xchk_pptrs	*pp = priv;

	struct xfs_inode	*dp = NULL;

	const struct xfs_parent_rec *pptr_rec = value;

	xfs_ino_t		parent_ino;

	unsigned int		lockmode;

	int			error;



	if (!(attr_flags & XFS_ATTR_PARENT))

		return 0;



	error = xfs_parent_from_attr(sc->mp, attr_flags, name, namelen, value,

			valuelen, &parent_ino, NULL);

	if (error) {

		xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, 0);

		return error;

	}



	/* No self-referential parent pointers. */

	if (parent_ino == sc->ip->i_ino) {

		xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, 0);

		return -ECANCELED;

	}



	pp->pptrs_found++;



	error = xchk_parent_iget(pp, pptr_rec, &dp);

	if (error)

		return error;

	if (!dp)

		return 0;



	/* Try to lock the inode. */

	lockmode = xchk_parent_lock_dir(sc, dp);

	if (!lockmode) {

		xchk_set_incomplete(sc);

		error = -ECANCELED;

		goto out_rele;

	}



	error = xchk_parent_dirent(pp, &xname, dp);

	if (error)

		goto out_unlock;



out_unlock:

	xfs_iunlock(dp, lockmode);

out_rele:

	xchk_irele(sc, dp);

	return error;

}



/*

 * Compare the number of parent pointers to the link count.  For

 * non-directories these should be the same.  For unlinked directories the

 * count should be zero; for linked directories, it should be nonzero.

 */

STATIC int

xchk_parent_count_pptrs(

	struct xchk_pptrs	*pp)

{

	struct xfs_scrub	*sc = pp->sc;



	if (S_ISDIR(VFS_I(sc->ip)->i_mode)) {

		if (sc->ip == sc->mp->m_rootip)

			pp->pptrs_found++;



		if (VFS_I(sc->ip)->i_nlink == 0 && pp->pptrs_found > 0)

			xchk_ino_set_corrupt(sc, sc->ip->i_ino);

		else if (VFS_I(sc->ip)->i_nlink > 0 &&

			 pp->pptrs_found == 0)

			xchk_ino_set_corrupt(sc, sc->ip->i_ino);

	} else {

		if (VFS_I(sc->ip)->i_nlink != pp->pptrs_found)

			xchk_ino_set_corrupt(sc, sc->ip->i_ino);

	}



	return 0;

}



/* Check parent pointers of a file. */

STATIC int

xchk_parent_pptr(

	struct xfs_scrub	*sc)

{

	struct xchk_pptrs	*pp;

	int			error;



	pp = kvzalloc(sizeof(struct xchk_pptrs), XCHK_GFP_FLAGS);

	if (!pp)

		return -ENOMEM;

	pp->sc = sc;



	error = xchk_xattr_walk(sc, sc->ip, xchk_parent_scan_attr, pp);

	if (error == -ECANCELED) {

		error = 0;

		goto out_pp;

	}

	if (error)

		goto out_pp;



	if (pp->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)

		goto out_pp;



	/*

	 * For subdirectories, make sure the dotdot entry references the same

	 * inode as the parent pointers.

	 *

	 * If we're scanning a /consistent/ directory, there should only be

	 * one parent pointer, and it should point to the same directory as

	 * the dotdot entry.

	 *

	 * However, a corrupt directory tree might feature a subdirectory with

	 * multiple parents.  The directory loop scanner is responsible for

	 * correcting that kind of problem, so for now we only validate that

	 * the dotdot entry matches /one/ of the parents.

	 */

	if (S_ISDIR(VFS_I(sc->ip)->i_mode)) {

		error = xchk_parent_pptr_and_dotdot(pp);

		if (error)

			goto out_pp;

	}



	if (pp->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)

		goto out_pp;



	/*

	 * Complain if the number of parent pointers doesn't match the link

	 * count.  This could be a sign of missing parent pointers (or an

	 * incorrect link count).

	 */

	error = xchk_parent_count_pptrs(pp);

	if (error)

		goto out_pp;



out_pp:

	kvfree(pp);

	return error;

}



/* Scrub a parent pointer. */

int

xchk_parent(
@@ -206,6 +574,9 @@ xchk_parent( 
	xfs_ino_t		parent_ino;

	int			error = 0;



	if (xfs_has_parent(mp))

		return xchk_parent_pptr(sc);



	/*

	 * If we're a directory, check that the '..' link points up to

	 * a directory that has one entry pointing to us.