5 files changed, 60 insertions, 24 deletions

diff --git a/fs/xfs/scrub/common.c b/fs/xfs/scrub/common.c
index 813ded91661b..9af653a1d351 100644
--- a/fs/xfs/scrub/common.c
+++ b/fs/xfs/scrub/common.c
@@ -718,6 +718,16 @@ xchk_checkpoint_log(
 	return 0;
 }
 
+/* Verify that an inode is allocated ondisk, then return its cached inode. */
+int
+xchk_iget(
+	struct xfs_scrub	*sc,
+	xfs_ino_t		inum,
+	struct xfs_inode	**ipp)
+{
+	return xfs_iget(sc->mp, sc->tp, inum, XFS_IGET_UNTRUSTED, 0, ipp);
+}
+
 /*
  * Given an inode and the scrub control structure, grab either the
  * inode referenced in the control structure or the inode passed in.
@@ -743,8 +753,7 @@ xchk_get_inode(
 	/* Look up the inode, see if the generation number matches. */
 	if (xfs_internal_inum(mp, sc->sm->sm_ino))
 		return -ENOENT;
-	error = xfs_iget(mp, NULL, sc->sm->sm_ino,
-			XFS_IGET_UNTRUSTED | XFS_IGET_DONTCACHE, 0, &ip);
+	error = xchk_iget(sc, sc->sm->sm_ino, &ip);
 	switch (error) {
 	case -ENOENT:
 		/* Inode doesn't exist, just bail out. */
@@ -768,7 +777,7 @@ xchk_get_inode(
 		pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, sc->sm->sm_ino));
 		if (pag) {
 			error = xfs_imap(pag, sc->tp, sc->sm->sm_ino, &imap,
-					XFS_IGET_UNTRUSTED | XFS_IGET_DONTCACHE);
+					XFS_IGET_UNTRUSTED);
 			xfs_perag_put(pag);
 			if (error)
 				return -ENOENT;
@@ -783,7 +792,7 @@ xchk_get_inode(
 		return error;
 	}
 	if (VFS_I(ip)->i_generation != sc->sm->sm_gen) {
-		xfs_irele(ip);
+		xchk_irele(sc, ip);
 		return -ENOENT;
 	}
 
@@ -791,6 +800,41 @@ xchk_get_inode(
 	return 0;
 }
 
+/* Release an inode, possibly dropping it in the process. */
+void
+xchk_irele(
+	struct xfs_scrub	*sc,
+	struct xfs_inode	*ip)
+{
+	if (current->journal_info != NULL) {
+		ASSERT(current->journal_info == sc->tp);
+
+		/*
+		 * If we are in a transaction, we /cannot/ drop the inode
+		 * ourselves, because the VFS will trigger writeback, which
+		 * can require a transaction.  Clear DONTCACHE to force the
+		 * inode to the LRU, where someone else can take care of
+		 * dropping it.
+		 *
+		 * Note that when we grabbed our reference to the inode, it
+		 * could have had an active ref and DONTCACHE set if a sysadmin
+		 * is trying to coerce a change in file access mode.  icache
+		 * hits do not clear DONTCACHE, so we must do it here.
+		 */
+		spin_lock(&VFS_I(ip)->i_lock);
+		VFS_I(ip)->i_state &= ~I_DONTCACHE;
+		spin_unlock(&VFS_I(ip)->i_lock);
+	} else if (atomic_read(&VFS_I(ip)->i_count) == 1) {
+		/*
+		 * If this is the last reference to the inode and the caller
+		 * permits it, set DONTCACHE to avoid thrashing.
+		 */
+		d_mark_dontcache(VFS_I(ip));
+	}
+
+	xfs_irele(ip);
+}
+
 /* Set us up to scrub a file's contents. */
 int
 xchk_setup_inode_contents(
diff --git a/fs/xfs/scrub/common.h b/fs/xfs/scrub/common.h
index 544f86ff8d1d..7e9e8b7b6cb0 100644
--- a/fs/xfs/scrub/common.h
+++ b/fs/xfs/scrub/common.h
@@ -137,6 +137,9 @@ int xchk_get_inode(struct xfs_scrub *sc);
 int xchk_setup_inode_contents(struct xfs_scrub *sc, unsigned int resblks);
 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);
+void xchk_irele(struct xfs_scrub *sc, struct xfs_inode *ip);
+
 /*
  * Don't bother cross-referencing if we already found corruption or cross
  * referencing discrepancies.
diff --git a/fs/xfs/scrub/dir.c b/fs/xfs/scrub/dir.c
index 6404201d3d36..0b491784b759 100644
--- a/fs/xfs/scrub/dir.c
+++ b/fs/xfs/scrub/dir.c
@@ -117,21 +117,15 @@ xchk_dir_actor(
 	}
 
 	/*
-	 * Grab the inode pointed to by the dirent.  We release the
-	 * inode before we cancel the scrub transaction.  Since we're
-	 * don't know a priori that releasing the inode won't trigger
-	 * eofblocks cleanup (which allocates what would be a nested
-	 * transaction), we can't use DONTCACHE here because DONTCACHE
-	 * inodes can trigger immediate inactive cleanup of the inode.
-	 * Use UNTRUSTED here to check the allocation status of the inode in
-	 * the inode btrees.
+	 * Grab the inode pointed to by the dirent.  We release the inode
+	 * before we cancel the scrub transaction.
 	 *
 	 * If _iget returns -EINVAL or -ENOENT then the child inode number is
 	 * garbage and the directory is corrupt.  If the _iget returns
 	 * -EFSCORRUPTED or -EFSBADCRC then the child is corrupt which is a
 	 *  cross referencing error.  Any other error is an operational error.
 	 */
-	error = xfs_iget(mp, sc->tp, ino, XFS_IGET_UNTRUSTED, 0, &ip);
+	error = xchk_iget(sc, ino, &ip);
 	if (error == -EINVAL || error == -ENOENT) {
 		error = -EFSCORRUPTED;
 		xchk_fblock_process_error(sc, XFS_DATA_FORK, 0, &error);
@@ -141,7 +135,7 @@ xchk_dir_actor(
 		goto out;
 
 	xchk_dir_check_ftype(sc, offset, ip, name->type);
-	xfs_irele(ip);
+	xchk_irele(sc, ip);
 out:
 	if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
 		return -ECANCELED;
diff --git a/fs/xfs/scrub/parent.c b/fs/xfs/scrub/parent.c
index b6c8f6dccc8f..58d5dfb7ea21 100644
--- a/fs/xfs/scrub/parent.c
+++ b/fs/xfs/scrub/parent.c
@@ -127,20 +127,15 @@ xchk_parent_validate(
 	expected_nlink = VFS_I(sc->ip)->i_nlink == 0 ? 0 : 1;
 
 	/*
-	 * Grab this parent inode.  We release the inode before we
-	 * cancel the scrub transaction.  Since we're don't know a
-	 * priori that releasing the inode won't trigger eofblocks
-	 * cleanup (which allocates what would be a nested transaction)
-	 * if the parent pointer erroneously points to a file, we
-	 * can't use DONTCACHE here because DONTCACHE inodes can trigger
-	 * immediate inactive cleanup of the inode.
+	 * Grab the parent directory inode.  This must be released before we
+	 * cancel the scrub transaction.
 	 *
 	 * If _iget returns -EINVAL or -ENOENT then the parent inode number is
 	 * garbage and the directory is corrupt.  If the _iget returns
 	 * -EFSCORRUPTED or -EFSBADCRC then the parent is corrupt which is a
 	 *  cross referencing error.  Any other error is an operational error.
 	 */
-	error = xfs_iget(mp, sc->tp, parent_ino, XFS_IGET_UNTRUSTED, 0, &dp);
+	error = xchk_iget(sc, parent_ino, &dp);
 	if (error == -EINVAL || error == -ENOENT) {
 		error = -EFSCORRUPTED;
 		xchk_fblock_process_error(sc, XFS_DATA_FORK, 0, &error);
@@ -176,7 +171,7 @@ xchk_parent_validate(
 out_unlock:
 	xfs_iunlock(dp, lock_mode);
 out_rele:
-	xfs_irele(dp);
+	xchk_irele(sc, dp);
 	return error;
 }
 
diff --git a/fs/xfs/scrub/scrub.c b/fs/xfs/scrub/scrub.c
index 787a9096ddef..03ec455318f4 100644
--- a/fs/xfs/scrub/scrub.c
+++ b/fs/xfs/scrub/scrub.c
@@ -181,7 +181,7 @@ xchk_teardown(
 			xfs_iunlock(sc->ip, sc->ilock_flags);
 		if (sc->ip != ip_in &&
 		    !xfs_internal_inum(sc->mp, sc->ip->i_ino))
-			xfs_irele(sc->ip);
+			xchk_irele(sc, sc->ip);
 		sc->ip = NULL;
 	}
 	if (sc->sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR)