xfs: wrap ilock/iunlock operations on sc->ip

Scrub tracks the resources that it's holding onto in the xfs_scrub
structure.  This includes the inode being checked (if applicable) and
the inode lock state of that inode.  Replace the open-coded structure
manipulation with a trivial helper to eliminate sources of error.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

fs/xfs/scrub/bmap.c

@@ -38,8 +38,7 @@ xchk_setup_inode_bmap(
 	if (error)
 		goto out;
 
-	sc->ilock_flags = XFS_IOLOCK_EXCL;
-	xfs_ilock(sc->ip, XFS_IOLOCK_EXCL);
+	xchk_ilock(sc, XFS_IOLOCK_EXCL);
 
 	/*
 	 * We don't want any ephemeral data/cow fork updates sitting around
@@ -50,8 +49,7 @@ xchk_setup_inode_bmap(
 	    sc->sm->sm_type != XFS_SCRUB_TYPE_BMBTA) {
 		struct address_space	*mapping = VFS_I(sc->ip)->i_mapping;
 
-		sc->ilock_flags |= XFS_MMAPLOCK_EXCL;
-		xfs_ilock(sc->ip, XFS_MMAPLOCK_EXCL);
+		xchk_ilock(sc, XFS_MMAPLOCK_EXCL);
 
 		inode_dio_wait(VFS_I(sc->ip));
 
@@ -79,9 +77,8 @@ xchk_setup_inode_bmap(
 	error = xchk_trans_alloc(sc, 0);
 	if (error)
 		goto out;
-	sc->ilock_flags |= XFS_ILOCK_EXCL;
-	xfs_ilock(sc->ip, XFS_ILOCK_EXCL);
 
+	xchk_ilock(sc, XFS_ILOCK_EXCL);
 out:
 	/* scrub teardown will unlock and release the inode */
 	return error;

fs/xfs/scrub/common.c

@@ -1022,20 +1022,48 @@ xchk_setup_inode_contents(
 		return error;
 
 	/* Lock the inode so the VFS cannot touch this file. */
-	sc->ilock_flags = XFS_IOLOCK_EXCL;
-	xfs_ilock(sc->ip, sc->ilock_flags);
+	xchk_ilock(sc, XFS_IOLOCK_EXCL);
 
 	error = xchk_trans_alloc(sc, resblks);
 	if (error)
 		goto out;
-	sc->ilock_flags |= XFS_ILOCK_EXCL;
-	xfs_ilock(sc->ip, XFS_ILOCK_EXCL);
-
+	xchk_ilock(sc, XFS_ILOCK_EXCL);
 out:
 	/* scrub teardown will unlock and release the inode for us */
 	return error;
 }
 
+void
+xchk_ilock(
+	struct xfs_scrub	*sc,
+	unsigned int		ilock_flags)
+{
+	xfs_ilock(sc->ip, ilock_flags);
+	sc->ilock_flags |= ilock_flags;
+}
+
+bool
+xchk_ilock_nowait(
+	struct xfs_scrub	*sc,
+	unsigned int		ilock_flags)
+{
+	if (xfs_ilock_nowait(sc->ip, ilock_flags)) {
+		sc->ilock_flags |= ilock_flags;
+		return true;
+	}
+
+	return false;
+}
+
+void
+xchk_iunlock(
+	struct xfs_scrub	*sc,
+	unsigned int		ilock_flags)
+{
+	sc->ilock_flags &= ~ilock_flags;
+	xfs_iunlock(sc->ip, ilock_flags);
+}
+
 /*
  * Predicate that decides if we need to evaluate the cross-reference check.
  * If there was an error accessing the cross-reference btree, just delete

fs/xfs/scrub/common.h

@@ -138,6 +138,11 @@ int xchk_setup_ag_btree(struct xfs_scrub *sc, bool force_log);
 int xchk_iget_for_scrubbing(struct xfs_scrub *sc);
 int xchk_setup_inode_contents(struct xfs_scrub *sc, unsigned int resblks);
 int xchk_install_live_inode(struct xfs_scrub *sc, struct xfs_inode *ip);
+
+void xchk_ilock(struct xfs_scrub *sc, unsigned int ilock_flags);
+bool xchk_ilock_nowait(struct xfs_scrub *sc, unsigned int ilock_flags);
+void xchk_iunlock(struct xfs_scrub *sc, unsigned int ilock_flags);
+
 void xchk_buffer_recheck(struct xfs_scrub *sc, struct xfs_buf *bp);
 
 int xchk_iget(struct xfs_scrub *sc, xfs_ino_t inum, struct xfs_inode **ipp);

fs/xfs/scrub/inode.c

@@ -32,15 +32,13 @@ xchk_prepare_iscrub(
 {
 	int			error;
 
-	sc->ilock_flags = XFS_IOLOCK_EXCL;
-	xfs_ilock(sc->ip, sc->ilock_flags);
+	xchk_ilock(sc, XFS_IOLOCK_EXCL);
 
 	error = xchk_trans_alloc(sc, 0);
 	if (error)
 		return error;
 
-	sc->ilock_flags |= XFS_ILOCK_EXCL;
-	xfs_ilock(sc->ip, XFS_ILOCK_EXCL);
+	xchk_ilock(sc, XFS_ILOCK_EXCL);
 	return 0;
 }
 

fs/xfs/scrub/parent.c

@@ -150,8 +150,8 @@ xchk_parent_validate(
 
 	lock_mode = xchk_parent_ilock_dir(dp);
 	if (!lock_mode) {
-		xfs_iunlock(sc->ip, XFS_ILOCK_EXCL);
-		xfs_ilock(sc->ip, XFS_ILOCK_EXCL);
+		xchk_iunlock(sc, XFS_ILOCK_EXCL);
+		xchk_ilock(sc, XFS_ILOCK_EXCL);
 		error = -EAGAIN;
 		goto out_rele;
 	}

fs/xfs/scrub/quota.c

@@ -64,8 +64,7 @@ xchk_setup_quota(
 	if (error)
 		return error;
 
-	xfs_ilock(sc->ip, XFS_ILOCK_EXCL);
-	sc->ilock_flags = XFS_ILOCK_EXCL;
+	xchk_ilock(sc, XFS_ILOCK_EXCL);
 	return 0;
 }
 
@@ -239,13 +238,11 @@ xchk_quota(
 	 * data fork we have to drop ILOCK_EXCL to use the regular dquot
 	 * functions.
 	 */
-	xfs_iunlock(sc->ip, sc->ilock_flags);
-	sc->ilock_flags = 0;
+	xchk_iunlock(sc, sc->ilock_flags);
 	sqi.sc = sc;
 	sqi.last_id = 0;
 	error = xfs_qm_dqiterate(mp, dqtype, xchk_quota_item, &sqi);
-	sc->ilock_flags = XFS_ILOCK_EXCL;
-	xfs_ilock(sc->ip, sc->ilock_flags);
+	xchk_ilock(sc, XFS_ILOCK_EXCL);
 	if (error == -ECANCELED)
 		error = 0;
 	if (!xchk_fblock_process_error(sc, XFS_DATA_FORK,

fs/xfs/scrub/rtbitmap.c

@@ -32,8 +32,7 @@ xchk_setup_rt(
 	if (error)
 		return error;
 
-	sc->ilock_flags = XFS_ILOCK_EXCL | XFS_ILOCK_RTBITMAP;
-	xfs_ilock(sc->ip, sc->ilock_flags);
+	xchk_ilock(sc, XFS_ILOCK_EXCL | XFS_ILOCK_RTBITMAP);
 	return 0;
 }
 
@@ -143,8 +142,8 @@ xchk_rtsummary(
 	 * flags so that we don't mix up the inode state that @sc tracks.
 	 */
 	sc->ip = rsumip;
-	sc->ilock_flags = XFS_ILOCK_EXCL | XFS_ILOCK_RTSUM;
-	xfs_ilock(sc->ip, sc->ilock_flags);
+	sc->ilock_flags = 0;
+	xchk_ilock(sc, XFS_ILOCK_EXCL | XFS_ILOCK_RTSUM);
 
 	/* Invoke the fork scrubber. */
 	error = xchk_metadata_inode_forks(sc);
@@ -155,7 +154,7 @@ xchk_rtsummary(
 	xchk_set_incomplete(sc);
 out:
 	/* Switch back to the rtbitmap inode and lock flags. */
-	xfs_iunlock(sc->ip, sc->ilock_flags);
+	xchk_iunlock(sc, XFS_ILOCK_EXCL | XFS_ILOCK_RTSUM);
 	sc->ilock_flags = old_ilock_flags;
 	sc->ip = old_ip;
 	return error;

fs/xfs/scrub/scrub.c

@@ -177,7 +177,7 @@ xchk_teardown(
 	}
 	if (sc->ip) {
 		if (sc->ilock_flags)
-			xfs_iunlock(sc->ip, sc->ilock_flags);
+			xchk_iunlock(sc, sc->ilock_flags);
 		xchk_irele(sc, sc->ip);
 		sc->ip = NULL;
 	}