Commit 3f113c27 authored by Darrick J. Wong's avatar Darrick J. Wong
Browse files

xfs: make xchk_iget safer in the presence of corrupt inode btrees 



When scrub is trying to iget an inode, ensure that it won't end up
deadlocked on a cycle in the inode btree by using an empty transaction
to store all the buffers.

Signed-off-by: default avatarDarrick J. Wong <djwong@kernel.org>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
parent 9c07bca7

fs/xfs/scrub/common.c

+4 −2
Original line number Diff line number Diff line
@@ -733,6 +733,8 @@ xchk_iget( 
	xfs_ino_t		inum,

	struct xfs_inode	**ipp)

{

	ASSERT(sc->tp != NULL);



	return xfs_iget(sc->mp, sc->tp, inum, XFS_IGET_UNTRUSTED, 0, ipp);

}
@@ -882,8 +884,8 @@ xchk_iget_for_scrubbing( 
	if (!xfs_verify_ino(sc->mp, sc->sm->sm_ino))

		return -ENOENT;



	/* Try a regular untrusted iget. */

	error = xchk_iget(sc, sc->sm->sm_ino, &ip);

	/* Try a safe untrusted iget. */

	error = xchk_iget_safe(sc, sc->sm->sm_ino, &ip);

	if (!error)

		return xchk_install_handle_inode(sc, ip);

	if (error == -ENOENT)

fs/xfs/scrub/common.h

+25 −0
Original line number Diff line number Diff line
@@ -151,12 +151,37 @@ void xchk_iunlock(struct xfs_scrub *sc, unsigned int ilock_flags); 


void xchk_buffer_recheck(struct xfs_scrub *sc, struct xfs_buf *bp);



/*

 * Grab the inode at @inum.  The caller must have created a scrub transaction

 * so that we can confirm the inumber by walking the inobt and not deadlock on

 * a loop in the inobt.

 */

int xchk_iget(struct xfs_scrub *sc, xfs_ino_t inum, struct xfs_inode **ipp);

int xchk_iget_agi(struct xfs_scrub *sc, xfs_ino_t inum,

		struct xfs_buf **agi_bpp, struct xfs_inode **ipp);

void xchk_irele(struct xfs_scrub *sc, struct xfs_inode *ip);

int xchk_install_handle_inode(struct xfs_scrub *sc, struct xfs_inode *ip);



/*

 * Safe version of (untrusted) xchk_iget that uses an empty transaction to

 * avoid deadlocking on loops in the inobt.  This should only be used in a

 * scrub or repair setup routine, and only prior to grabbing a transaction.

 */

static inline int

xchk_iget_safe(struct xfs_scrub *sc, xfs_ino_t inum, struct xfs_inode **ipp)

{

	int	error;



	ASSERT(sc->tp == NULL);



	error = xchk_trans_alloc(sc, 0);

	if (error)

		return error;

	error = xchk_iget(sc, inum, ipp);

	xchk_trans_cancel(sc);

	return error;

}



/*

 * Don't bother cross-referencing if we already found corruption or cross

 * referencing discrepancies.

fs/xfs/scrub/inode.c

+2 −2
Original line number Diff line number Diff line
@@ -95,8 +95,8 @@ xchk_setup_inode( 
	if (!xfs_verify_ino(sc->mp, sc->sm->sm_ino))

		return -ENOENT;



	/* Try a regular untrusted iget. */

	error = xchk_iget(sc, sc->sm->sm_ino, &ip);

	/* Try a safe untrusted iget. */

	error = xchk_iget_safe(sc, sc->sm->sm_ino, &ip);

	if (!error)

		return xchk_install_handle_iscrub(sc, ip);

	if (error == -ENOENT)