[PATCH 25/30 V2] libxfs: fix root inode handling inconsistencies

[Dave Chinner <david@fromorbit.com>]

From: Dave Chinner <dchinner@redhat.com>

When "mounting" a filesystem via libxfs_mount(), callers can tell
libxfs to read the root and realtime inodes into cache. However,
when unmounting the filesystem, libxfs_unmount() used to
unconditionally free root inodes if they were present.

This leads to interesting issues like in mkfs, when it handles
creation, reading and freeing of the root and rt inodes itself.
It, however, passes in the flag to tell libxfs_mount() to read the
root inode, and so when unmounting throws an error like:

cache_node_put: node put on refcount 0 (node=0x684610)

when a second libxfs_iput() call is made on the root inode.

As it turns out, nothing ever uses mp->m_rootip and so we don't need
to read it in or free it, or even have a pointer to it in the struct
xfs_mount, so kill the m_rootip and LIBXFS_MOUNT_ROOTINOS parameter
completely.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
V2: just kill m_rootino and LIBXFS_MOUNT_ROOTINOS altogether.

 copy/xfs_copy.c  |  2 +-
 db/init.c        | 13 +++++--------
 include/libxfs.h | 12 +++++-------
 libxfs/init.c    | 27 ++++-----------------------
 mkfs/proto.c     |  1 -
 mkfs/xfs_mkfs.c  |  4 ++--
 repair/phase6.c  |  2 --
 7 files changed, 17 insertions(+), 44 deletions(-)

diff --git a/copy/xfs_copy.c b/copy/xfs_copy.c
index bb37279..9986fbf 100644
--- a/copy/xfs_copy.c
+++ b/copy/xfs_copy.c
@@ -684,7 +684,7 @@ main(int argc, char **argv)
 	sb = &mbuf.m_sb;
 	libxfs_sb_from_disk(sb, XFS_BUF_TO_SBP(sbp));
 
-	mp = libxfs_mount(&mbuf, sb, xargs.ddev, xargs.logdev, xargs.rtdev, 1);
+	mp = libxfs_mount(&mbuf, sb, xargs.ddev, xargs.logdev, xargs.rtdev, 0);
 	if (mp == NULL) {
 		do_log(_("%s: %s filesystem failed to initialize\n"
 			"%s: Aborting.\n"), progname, source_name, progname);
diff --git a/db/init.c b/db/init.c
index a9b357b..7dd31ca 100644
--- a/db/init.c
+++ b/db/init.c
@@ -144,15 +144,12 @@ init(
 	}
 
 	mp = libxfs_mount(&xmount, sbp, x.ddev, x.logdev, x.rtdev,
-				LIBXFS_MOUNT_ROOTINOS | LIBXFS_MOUNT_DEBUGGER);
+			  LIBXFS_MOUNT_DEBUGGER);
 	if (!mp) {
-		mp = libxfs_mount(&xmount, sbp, x.ddev, x.logdev, x.rtdev,
-				LIBXFS_MOUNT_DEBUGGER);
-		if (!mp) {
-			fprintf(stderr, _("%s: device %s unusable (not an XFS "
-				"filesystem?)\n"), progname, fsdevice);
-			exit(1);
-		}
+		fprintf(stderr,
+			_("%s: device %s unusable (not an XFS filesystem?)\n"),
+			progname, fsdevice);
+		exit(1);
 	}
 	blkbb = 1 << mp->m_blkbb_log;
 
diff --git a/include/libxfs.h b/include/libxfs.h
index d28ac48..169dfc5 100644
--- a/include/libxfs.h
+++ b/include/libxfs.h
@@ -167,7 +167,6 @@ typedef struct xfs_mount {
 	uint			m_rsumsize;	/* size of rt summary, bytes */
 	struct xfs_inode	*m_rbmip;	/* pointer to bitmap inode */
 	struct xfs_inode	*m_rsumip;	/* pointer to summary inode */
-	struct xfs_inode	*m_rootip;	/* pointer to root directory */
 	struct xfs_buftarg	*m_ddev_targp;
 	struct xfs_buftarg	*m_logdev_targp;
 	struct xfs_buftarg	*m_rtdev_targp;
@@ -259,12 +258,11 @@ typedef struct xfs_perag {
 	int		pagb_count;	/* pagb slots in use */
 } xfs_perag_t;
 
-#define LIBXFS_MOUNT_ROOTINOS		0x0001
-#define LIBXFS_MOUNT_DEBUGGER		0x0002
-#define LIBXFS_MOUNT_32BITINODES	0x0004
-#define LIBXFS_MOUNT_32BITINOOPT	0x0008
-#define LIBXFS_MOUNT_COMPAT_ATTR	0x0010
-#define LIBXFS_MOUNT_ATTR2		0x0020
+#define LIBXFS_MOUNT_DEBUGGER		0x0001
+#define LIBXFS_MOUNT_32BITINODES	0x0002
+#define LIBXFS_MOUNT_32BITINOOPT	0x0004
+#define LIBXFS_MOUNT_COMPAT_ATTR	0x0008
+#define LIBXFS_MOUNT_ATTR2		0x0010
 
 #define LIBXFS_IHASHSIZE(sbp)		(1<<10)
 #define LIBXFS_BHASHSIZE(sbp) 		(1<<10)
diff --git a/libxfs/init.c b/libxfs/init.c
index 229aa50..6be0ac4 100644
--- a/libxfs/init.c
+++ b/libxfs/init.c
@@ -688,8 +688,6 @@ libxfs_mount(
 	libxfs_buftarg_init(mp, dev, logdev, rtdev);
 
 	mp->m_flags = (LIBXFS_MOUNT_32BITINODES|LIBXFS_MOUNT_32BITINOOPT);
-	if (flags & LIBXFS_MOUNT_ROOTINOS)
-		mp->m_flags |= LIBXFS_MOUNT_ROOTINOS;
 
 	mp->m_sb = *sb;
 	INIT_RADIX_TREE(&mp->m_perag_tree, GFP_KERNEL);
@@ -813,30 +811,15 @@ libxfs_mount(
 		exit(1);
 	}
 
-	/*
-	 * mkfs calls mount before the root inode is allocated.
-	 */
-	if ((flags & LIBXFS_MOUNT_ROOTINOS) && sbp->sb_rootino != NULLFSINO) {
-		error = libxfs_iget(mp, NULL, sbp->sb_rootino, 0,
-				&mp->m_rootip, 0);
-		if (error) {
-			fprintf(stderr, _("%s: cannot read root inode (%d)\n"),
-				progname, error);
-			if (!(flags & LIBXFS_MOUNT_DEBUGGER))
-				return NULL;
-		}
-		ASSERT(mp->m_rootip != NULL);
-	}
-	if ((flags & LIBXFS_MOUNT_ROOTINOS) && rtmount_inodes(mp)) {
-		if (mp->m_rootip)
-			libxfs_iput(mp->m_rootip, 0);
+	/* set up the realtime inodes if they exist */
+	error = rtmount_inodes(mp);
+	if (error)
 		return NULL;
-	}
 
 	/*
 	 * mkfs calls mount before the AGF/AGI structures are written.
 	 */
-	if ((flags & LIBXFS_MOUNT_ROOTINOS) && sbp->sb_rootino != NULLFSINO &&
+	if (sbp->sb_rootino != NULLFSINO &&
 	    xfs_sb_version_haslazysbcount(&mp->m_sb)) {
 		error = xfs_initialize_perag_data(mp, sbp->sb_agcount);
 		if (error) {
@@ -869,8 +852,6 @@ libxfs_umount(xfs_mount_t *mp)
 	int			agno;
 
 	libxfs_rtmount_destroy(mp);
-	if ((mp->m_flags & LIBXFS_MOUNT_ROOTINOS) && mp->m_rootip)
-		libxfs_iput(mp->m_rootip, 0);
 	libxfs_icache_purge();
 	libxfs_bcache_purge();
 
diff --git a/mkfs/proto.c b/mkfs/proto.c
index 0cdef41..4cc0df6 100644
--- a/mkfs/proto.c
+++ b/mkfs/proto.c
@@ -543,7 +543,6 @@ parseproto(
 			pip = ip;
 			mp->m_sb.sb_rootino = ip->i_ino;
 			libxfs_mod_sb(tp, XFS_SB_ROOTINO);
-			mp->m_rootip = ip;
 			isroot = 1;
 		} else {
 			libxfs_trans_ijoin(tp, pip, 0);
diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
index 355708c..d37e948 100644
--- a/mkfs/xfs_mkfs.c
+++ b/mkfs/xfs_mkfs.c
@@ -2582,6 +2582,7 @@ _("size %s specified for log subvolume is too large, maximum is %lld blocks\n"),
 	memset(XFS_BUF_PTR(buf), 0, sectorsize);
 	libxfs_sb_to_disk((void *)XFS_BUF_PTR(buf), sbp, XFS_SB_ALL_BITS);
 	libxfs_writebuf(buf, LIBXFS_EXIT_ON_FAILURE);
+	libxfs_purgebuf(buf);
 
 	/*
 	 * If the data area is a file, then grow it out to its final size
@@ -2616,7 +2617,7 @@ _("size %s specified for log subvolume is too large, maximum is %lld blocks\n"),
 		(xfs_extlen_t)XFS_FSB_TO_BB(mp, logblocks),
 		&sbp->sb_uuid, logversion, lsunit, XLOG_FMT);
 
-	mp = libxfs_mount(mp, sbp, xi.ddev, xi.logdev, xi.rtdev, 1);
+	mp = libxfs_mount(mp, sbp, xi.ddev, xi.logdev, xi.rtdev, 0);
 	if (mp == NULL) {
 		fprintf(stderr, _("%s: filesystem failed to initialize\n"),
 			progname);
@@ -2887,7 +2888,6 @@ _("size %s specified for log subvolume is too large, maximum is %lld blocks\n"),
 	/*
 	 * Allocate the root inode and anything else in the proto file.
 	 */
-	mp->m_rootip = NULL;
 	parse_proto(mp, &fsx, &protostring);
 
 	/*
diff --git a/repair/phase6.c b/repair/phase6.c
index 2a37438..5307acf 100644
--- a/repair/phase6.c
+++ b/repair/phase6.c
@@ -856,8 +856,6 @@ mk_root_dir(xfs_mount_t *mp)
 	ip->i_df.if_bytes = ip->i_df.if_real_bytes = 0;
 	ip->i_df.if_u1.if_extents = NULL;
 
-	mp->m_rootip = ip;
-
 	/*
 	 * initialize the directory
 	 */

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