xfs: create imeta abstractions to get and set metadata inodes

Create some helper routines to get and set metadata inode numbers
instead of open-coding them throughout xfs.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>

6 files changed, 511 insertions, 4 deletions

diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
index b19e36d762b0..f14fa453586b 100644
--- a/fs/xfs/Makefile
+++ b/fs/xfs/Makefile
@@ -37,6 +37,7 @@ xfs-y				+= $(addprefix libxfs/, \
 				   xfs_ialloc.o \
 				   xfs_ialloc_btree.o \
 				   xfs_iext_tree.o \
+				   xfs_imeta.o \
 				   xfs_inode_fork.o \
 				   xfs_inode_buf.o \
 				   xfs_inode_util.o \
diff --git a/fs/xfs/libxfs/xfs_imeta.c b/fs/xfs/libxfs/xfs_imeta.c
new file mode 100644
index 000000000000..57dce8387028
--- /dev/null
+++ b/fs/xfs/libxfs/xfs_imeta.c
@@ -0,0 +1,406 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2021 Oracle.  All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_shared.h"
+#include "xfs_format.h"
+#include "xfs_log_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_bit.h"
+#include "xfs_sb.h"
+#include "xfs_mount.h"
+#include "xfs_defer.h"
+#include "xfs_trans.h"
+#include "xfs_imeta.h"
+#include "xfs_trace.h"
+#include "xfs_inode.h"
+#include "xfs_quota.h"
+#include "xfs_ialloc.h"
+
+/*
+ * Metadata Inode Number Management
+ * ================================
+ *
+ * These functions provide an abstraction layer for looking up, creating, and
+ * deleting metadata inodes.  These pointers live in the in-core superblock,
+ * so the functions moderate access to those fields and take care of logging.
+ *
+ * For the five existing metadata inodes (real time bitmap & summary; and the
+ * user, group, and quotas) we'll continue to maintain the in-core superblock
+ * inodes for reads and only require xfs_imeta_create and xfs_imeta_unlink to
+ * persist changes.  New metadata inode types must only use the xfs_imeta_*
+ * functions.
+ *
+ * Callers wishing to create or unlink a metadata inode must pass in a
+ * xfs_imeta_end structure.  After committing or cancelling the transaction,
+ * this structure must be passed to xfs_imeta_end_update to free resources that
+ * cannot be freed during the transaction.
+ *
+ * Right now we only support callers passing in the predefined metadata inode
+ * paths; the goal is that callers will some day locate metadata inodes based
+ * on path lookups into a metadata directory structure.
+ */
+
+/* Static metadata inode paths */
+
+const struct xfs_imeta_path XFS_IMETA_RTBITMAP = {
+	.bogus = 0,
+};
+
+const struct xfs_imeta_path XFS_IMETA_RTSUMMARY = {
+	.bogus = 1,
+};
+
+const struct xfs_imeta_path XFS_IMETA_USRQUOTA = {
+	.bogus = 2,
+};
+
+const struct xfs_imeta_path XFS_IMETA_GRPQUOTA = {
+	.bogus = 3,
+};
+
+const struct xfs_imeta_path XFS_IMETA_PRJQUOTA = {
+	.bogus = 4,
+};
+
+/* Are these two paths equal? */
+STATIC bool
+xfs_imeta_path_compare(
+	const struct xfs_imeta_path	*a,
+	const struct xfs_imeta_path	*b)
+{
+	return a == b;
+}
+
+/* Is this path ok? */
+static inline bool
+xfs_imeta_path_check(
+	const struct xfs_imeta_path	*path)
+{
+	return true;
+}
+
+/* Functions for storing and retrieving superblock inode values. */
+
+/* Mapping of metadata inode paths to in-core superblock values. */
+static const struct xfs_imeta_sbmap {
+	const struct xfs_imeta_path	*path;
+	unsigned int			offset;
+} xfs_imeta_sbmaps[] = {
+	{
+		.path	= &XFS_IMETA_RTBITMAP,
+		.offset	= offsetof(struct xfs_sb, sb_rbmino),
+	},
+	{
+		.path	= &XFS_IMETA_RTSUMMARY,
+		.offset	= offsetof(struct xfs_sb, sb_rsumino),
+	},
+	{
+		.path	= &XFS_IMETA_USRQUOTA,
+		.offset	= offsetof(struct xfs_sb, sb_uquotino),
+	},
+	{
+		.path	= &XFS_IMETA_GRPQUOTA,
+		.offset	= offsetof(struct xfs_sb, sb_gquotino),
+	},
+	{
+		.path	= &XFS_IMETA_PRJQUOTA,
+		.offset	= offsetof(struct xfs_sb, sb_pquotino),
+	},
+	{ NULL, 0 },
+};
+
+/* Return a pointer to the in-core superblock inode value. */
+static inline xfs_ino_t *
+xfs_imeta_sbmap_to_inop(
+	struct xfs_mount		*mp,
+	const struct xfs_imeta_sbmap	*map)
+{
+	return (xfs_ino_t *)(((char *)&mp->m_sb) + map->offset);
+}
+
+/* Compute location of metadata inode pointer in the in-core superblock */
+static inline xfs_ino_t *
+xfs_imeta_path_to_sb_inop(
+	struct xfs_mount		*mp,
+	const struct xfs_imeta_path	*path)
+{
+	const struct xfs_imeta_sbmap	*p;
+
+	for (p = xfs_imeta_sbmaps; p->path; p++)
+		if (xfs_imeta_path_compare(p->path, path))
+			return xfs_imeta_sbmap_to_inop(mp, p);
+
+	return NULL;
+}
+
+/* Look up a superblock metadata inode by its path. */
+STATIC int
+xfs_imeta_sb_lookup(
+	struct xfs_mount		*mp,
+	const struct xfs_imeta_path	*path,
+	xfs_ino_t			*inop)
+{
+	xfs_ino_t			*sb_inop;
+
+	sb_inop = xfs_imeta_path_to_sb_inop(mp, path);
+	if (!sb_inop)
+		return -EINVAL;
+
+	trace_xfs_imeta_sb_lookup(mp, sb_inop);
+	*inop = *sb_inop;
+	return 0;
+}
+
+/*
+ * Create a new metadata inode and set a superblock pointer to this new inode.
+ * The superblock field must not already be pointing to an inode.
+ */
+STATIC int
+xfs_imeta_sb_create(
+	struct xfs_trans		**tpp,
+	const struct xfs_imeta_path	*path,
+	umode_t				mode,
+	unsigned int			flags,
+	struct xfs_inode		**ipp)
+{
+	struct xfs_icreate_args		args = {
+		.nlink			= S_ISDIR(mode) ? 2 : 1,
+	};
+	struct xfs_mount		*mp = (*tpp)->t_mountp;
+	xfs_ino_t			*sb_inop;
+	xfs_ino_t			ino;
+	int				error;
+
+	xfs_icreate_args_rootfile(&args, mode);
+
+	/* Reject if the sb already points to some inode. */
+	sb_inop = xfs_imeta_path_to_sb_inop(mp, path);
+	if (!sb_inop)
+		return -EINVAL;
+
+	if (*sb_inop != NULLFSINO)
+		return -EEXIST;
+
+	/* Create a new inode and set the sb pointer. */
+	error = xfs_dialloc(tpp, 0, mode, &ino);
+	if (error)
+		return error;
+	error = xfs_icreate(*tpp, ino, &args, ipp);
+	if (error)
+		return error;
+
+	/* Attach dquots to this file.  Caller should have allocated them! */
+	if (!(flags & XFS_IMETA_CREATE_NOQUOTA)) {
+		error = xfs_qm_dqattach_locked(*ipp, false);
+		if (error)
+			return error;
+		xfs_trans_mod_dquot_byino(*tpp, *ipp, XFS_TRANS_DQ_ICOUNT, 1);
+	}
+
+	/* Update superblock pointer. */
+	*sb_inop = ino;
+	trace_xfs_imeta_sb_create(mp, sb_inop);
+	xfs_log_sb(*tpp);
+	return 0;
+}
+
+/*
+ * Clear the given inode pointer from the superblock and drop the link count
+ * of the metadata inode.
+ */
+STATIC int
+xfs_imeta_sb_unlink(
+	struct xfs_trans		**tpp,
+	const struct xfs_imeta_path	*path,
+	struct xfs_inode		*ip)
+{
+	struct xfs_mount		*mp = (*tpp)->t_mountp;
+	xfs_ino_t			*sb_inop;
+
+	sb_inop = xfs_imeta_path_to_sb_inop(mp, path);
+	if (!sb_inop)
+		return -EINVAL;
+
+	/* Reject if the sb doesn't point to the inode that was passed in. */
+	if (*sb_inop != ip->i_ino)
+		return -ENOENT;
+
+	*sb_inop = NULLFSINO;
+	trace_xfs_imeta_sb_unlink(mp, sb_inop);
+	xfs_log_sb(*tpp);
+	return xfs_droplink(*tpp, ip);
+}
+
+/* Set the given inode pointer in the superblock. */
+STATIC int
+xfs_imeta_sb_link(
+	struct xfs_trans		*tp,
+	const struct xfs_imeta_path	*path,
+	struct xfs_inode		*ip)
+{
+	struct xfs_mount		*mp = tp->t_mountp;
+	xfs_ino_t			*sb_inop;
+
+	sb_inop = xfs_imeta_path_to_sb_inop(mp, path);
+	if (!sb_inop)
+		return -EINVAL;
+	if (*sb_inop == NULLFSINO)
+		return -EEXIST;
+
+	xfs_ilock(ip, XFS_ILOCK_EXCL);
+	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
+
+	inc_nlink(VFS_I(ip));
+	*sb_inop = ip->i_ino;
+	trace_xfs_imeta_sb_link(mp, sb_inop);
+	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
+	xfs_log_sb(tp);
+	return 0;
+}
+
+/* General functions for managing metadata inode pointers */
+
+/*
+ * Is this metadata inode pointer ok?  We allow the fields to be set to
+ * NULLFSINO if the metadata structure isn't present, and we don't allow
+ * obviously incorrect inode pointers.
+ */
+static inline bool
+xfs_imeta_verify(
+	struct xfs_mount	*mp,
+	xfs_ino_t		ino)
+{
+	if (ino == NULLFSINO)
+		return true;
+	return xfs_verify_ino(mp, ino);
+}
+
+/* Look up a metadata inode by its path. */
+int
+xfs_imeta_lookup(
+	struct xfs_mount		*mp,
+	const struct xfs_imeta_path	*path,
+	xfs_ino_t			*inop)
+{
+	xfs_ino_t			ino;
+	int				error;
+
+	ASSERT(xfs_imeta_path_check(path));
+
+	error = xfs_imeta_sb_lookup(mp, path, &ino);
+	if (error)
+		return error;
+
+	if (!xfs_imeta_verify(mp, ino))
+		return -EFSCORRUPTED;
+
+	*inop = ino;
+	return 0;
+}
+
+/*
+ * Create a metadata inode with the given @mode, and insert it into the
+ * metadata directory tree at the given @path.  The path (up to the final
+ * component) must already exist.  The new metadata inode @ipp will be ijoined
+ * and logged to @tpp, with the ILOCK held until the next transaction commit.
+ * The caller must provide a @cleanup structure.
+ *
+ * Callers must ensure that the root dquots are allocated, if applicable.
+ *
+ * NOTE: This function may pass a child inode @ipp back to the caller even if
+ * it returns a negative error code.  If an inode is passed back, the caller
+ * must finish setting up the incore inode before releasing it.
+ */
+int
+xfs_imeta_create(
+	struct xfs_trans		**tpp,
+	const struct xfs_imeta_path	*path,
+	umode_t				mode,
+	unsigned int			flags,
+	struct xfs_inode		**ipp,
+	struct xfs_imeta_end		*cleanup)
+{
+	ASSERT(xfs_imeta_path_check(path));
+	*ipp = NULL;
+
+	return xfs_imeta_sb_create(tpp, path, mode, flags, ipp);
+}
+
+/*
+ * Unlink a metadata inode @ip from the metadata directory given by @path.  The
+ * metadata inode must not be ILOCKed.  Upon return, the inode will be ijoined
+ * and logged to @tpp, and returned with reduced link count, ready to be
+ * released.  The caller must provide a @cleanup structure.
+ */
+int
+xfs_imeta_unlink(
+	struct xfs_trans		**tpp,
+	const struct xfs_imeta_path	*path,
+	struct xfs_inode		*ip,
+	struct xfs_imeta_end		*cleanup)
+{
+	ASSERT(xfs_imeta_path_check(path));
+	ASSERT(xfs_imeta_verify((*tpp)->t_mountp, ip->i_ino));
+
+	return xfs_imeta_sb_unlink(tpp, path, ip);
+}
+
+/*
+ * Link the metadata directory given by @path point to the given inode number.
+ * The path must not already exist.  The caller must not hold the ILOCK, and
+ * the function will return with the inode joined to the transaction.
+ */
+int
+xfs_imeta_link(
+	struct xfs_trans		*tp,
+	const struct xfs_imeta_path	*path,
+	struct xfs_inode		*ip,
+	struct xfs_imeta_end		*cleanup)
+{
+	ASSERT(xfs_imeta_path_check(path));
+
+	return xfs_imeta_sb_link(tp, path, ip);
+}
+
+/*
+ * Clean up after committing (or cancelling) a metadata inode creation or
+ * removal.
+ */
+void
+xfs_imeta_end_update(
+	struct xfs_mount		*mp,
+	struct xfs_imeta_end		*cleanup,
+	int				error)
+{
+	trace_xfs_imeta_end_update(mp, error, __return_address);
+}
+
+/* Does this inode number refer to a static metadata inode? */
+bool
+xfs_is_static_meta_ino(
+	struct xfs_mount		*mp,
+	xfs_ino_t			ino)
+{
+	const struct xfs_imeta_sbmap	*p;
+
+	if (ino == NULLFSINO)
+		return false;
+
+	for (p = xfs_imeta_sbmaps; p->path; p++)
+		if (ino == *xfs_imeta_sbmap_to_inop(mp, p))
+			return true;
+
+	return false;
+}
+
+/* Ensure that the in-core superblock has all the values that it should. */
+int
+xfs_imeta_mount(
+	struct xfs_mount	*mp)
+{
+	return 0;
+}
diff --git a/fs/xfs/libxfs/xfs_imeta.h b/fs/xfs/libxfs/xfs_imeta.h
new file mode 100644
index 000000000000..9d0dfafa14fd
--- /dev/null
+++ b/fs/xfs/libxfs/xfs_imeta.h
@@ -0,0 +1,45 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2021 Oracle.  All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#ifndef __XFS_IMETA_H__
+#define __XFS_IMETA_H__
+
+/* Key for looking up metadata inodes. */
+struct xfs_imeta_path {
+	/* Temporary: integer to keep the static imeta definitions unique */
+	int		bogus;
+};
+
+/* Cleanup widget for metadata inode creation and deletion. */
+struct xfs_imeta_end {
+	/* empty for now */
+};
+
+/* Lookup keys for static metadata inodes. */
+extern const struct xfs_imeta_path XFS_IMETA_RTBITMAP;
+extern const struct xfs_imeta_path XFS_IMETA_RTSUMMARY;
+extern const struct xfs_imeta_path XFS_IMETA_USRQUOTA;
+extern const struct xfs_imeta_path XFS_IMETA_GRPQUOTA;
+extern const struct xfs_imeta_path XFS_IMETA_PRJQUOTA;
+
+int xfs_imeta_lookup(struct xfs_mount *mp, const struct xfs_imeta_path *path,
+		     xfs_ino_t *ino);
+
+/* Don't allocate quota for this file. */
+#define XFS_IMETA_CREATE_NOQUOTA	(1 << 0)
+int xfs_imeta_create(struct xfs_trans **tpp, const struct xfs_imeta_path *path,
+		     umode_t mode, unsigned int flags, struct xfs_inode **ipp,
+		     struct xfs_imeta_end *cleanup);
+int xfs_imeta_unlink(struct xfs_trans **tpp, const struct xfs_imeta_path *path,
+		     struct xfs_inode *ip, struct xfs_imeta_end *cleanup);
+int xfs_imeta_link(struct xfs_trans *tp, const struct xfs_imeta_path *path,
+		   struct xfs_inode *ip, struct xfs_imeta_end *cleanup);
+void xfs_imeta_end_update(struct xfs_mount *mp, struct xfs_imeta_end *cleanup,
+			  int error);
+
+bool xfs_is_static_meta_ino(struct xfs_mount *mp, xfs_ino_t ino);
+int xfs_imeta_mount(struct xfs_mount *mp);
+
+#endif /* __XFS_IMETA_H__ */
diff --git a/fs/xfs/libxfs/xfs_types.c b/fs/xfs/libxfs/xfs_types.c
index 96647008f9e0..d12dc9a4bdb9 100644
--- a/fs/xfs/libxfs/xfs_types.c
+++ b/fs/xfs/libxfs/xfs_types.c
@@ -12,6 +12,7 @@
 #include "xfs_bit.h"
 #include "xfs_mount.h"
 #include "xfs_ag.h"
+#include "xfs_imeta.h"
 
 /* Find the size of the AG, in blocks. */
 inline xfs_agblock_t
@@ -188,9 +189,7 @@ xfs_internal_inum(
 	struct xfs_mount	*mp,
 	xfs_ino_t		ino)
 {
-	return ino == mp->m_sb.sb_rbmino || ino == mp->m_sb.sb_rsumino ||
-		(xfs_has_quota(mp) &&
-		 xfs_is_quota_inode(&mp->m_sb, ino));
+	return xfs_is_static_meta_ino(mp, ino);
 }
 
 /*
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 490bf1266661..a53e6aa54675 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -33,6 +33,7 @@
 #include "xfs_health.h"
 #include "xfs_trace.h"
 #include "xfs_ag.h"
+#include "xfs_imeta.h"
 
 static DEFINE_MUTEX(xfs_uuid_table_mutex);
 static int xfs_uuid_table_size;
@@ -514,6 +515,22 @@ xfs_check_summary_counts(
 	return xfs_initialize_perag_data(mp, mp->m_sb.sb_agcount);
 }
 
+STATIC int
+xfs_mountfs_imeta(
+	struct xfs_mount	*mp)
+{
+	int			error;
+
+	error = xfs_imeta_mount(mp);
+	if (error) {
+		xfs_warn(mp, "Failed to load metadata inode info, error %d",
+				error);
+		return error;
+	}
+
+	return 0;
+}
+
 /*
  * Flush and reclaim dirty inodes in preparation for unmount. Inodes and
  * internal inode structures can be sitting in the CIL and AIL at this point,
@@ -807,6 +824,11 @@ xfs_mountfs(
 		mp->m_features |= XFS_FEAT_ATTR2;
 	}
 
+	/* Load the metadata directory tree. */
+	error = xfs_mountfs_imeta(mp);
+	if (error)
+		goto out_log_dealloc;
+
 	/*
 	 * Get and sanity-check the root inode.
 	 * Save the pointer to it in the mount structure.
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index e235df640b60..56446233f3f0 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -149,7 +149,7 @@ DEFINE_ATTR_LIST_EVENT(xfs_attr_list_notfound);
 DEFINE_ATTR_LIST_EVENT(xfs_attr_leaf_list);
 DEFINE_ATTR_LIST_EVENT(xfs_attr_node_list);
 
-TRACE_EVENT(xlog_intent_recovery_failed,
+DECLARE_EVENT_CLASS(xfs_fs_error_class,
 	TP_PROTO(struct xfs_mount *mp, int error, void *function),
 	TP_ARGS(mp, error, function),
 	TP_STRUCT__entry(
@@ -166,6 +166,11 @@ TRACE_EVENT(xlog_intent_recovery_failed,
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
 		  __entry->error, __entry->function)
 );
+#define DEFINE_FS_ERROR_EVENT(name)	\
+DEFINE_EVENT(xfs_fs_error_class, name,	\
+	TP_PROTO(struct xfs_mount *mp, int error, void *function), \
+	TP_ARGS(mp, error, function))
+DEFINE_FS_ERROR_EVENT(xlog_intent_recovery_failed);
 
 DECLARE_EVENT_CLASS(xfs_perag_class,
 	TP_PROTO(struct xfs_mount *mp, xfs_agnumber_t agno, int refcount,
@@ -4581,6 +4586,35 @@ TRACE_EVENT(xfs_swapext_delta_nextents,
 		  __entry->d_nexts1, __entry->d_nexts2)
 );
 
+DECLARE_EVENT_CLASS(xfs_imeta_sb_class,
+	TP_PROTO(struct xfs_mount *mp, xfs_ino_t *sb_inop),
+	TP_ARGS(mp, sb_inop),
+	TP_STRUCT__entry(
+		__field(dev_t, dev)
+		__field(unsigned int, sb_offset)
+		__field(xfs_ino_t, ino)
+	),
+	TP_fast_assign(
+		__entry->dev = mp->m_super->s_dev;
+		__entry->sb_offset = (char *)sb_inop - (char *)&mp->m_sb;
+		__entry->ino = *sb_inop;
+	),
+	TP_printk("dev %d:%d sb_offset 0x%x ino 0x%llx",
+		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  __entry->sb_offset,
+		  __entry->ino)
+)
+
+#define DEFINE_IMETA_SB_EVENT(name) \
+DEFINE_EVENT(xfs_imeta_sb_class, name, \
+	TP_PROTO(struct xfs_mount *mp, xfs_ino_t *sb_inop), \
+	TP_ARGS(mp, sb_inop))
+DEFINE_IMETA_SB_EVENT(xfs_imeta_sb_lookup);
+DEFINE_IMETA_SB_EVENT(xfs_imeta_sb_create);
+DEFINE_IMETA_SB_EVENT(xfs_imeta_sb_unlink);
+DEFINE_IMETA_SB_EVENT(xfs_imeta_sb_link);
+DEFINE_FS_ERROR_EVENT(xfs_imeta_end_update);
+
 #endif /* _TRACE_XFS_H */
 
 #undef TRACE_INCLUDE_PATH