init android origin source code

1 files changed, 2567 insertions, 0 deletions

diff --git a/ANDROID_3.4.5/fs/xfs/xfs_mount.c b/ANDROID_3.4.5/fs/xfs/xfs_mount.c
new file mode 100644
index 00000000..1ffead4b
--- /dev/null
+++ b/ANDROID_3.4.5/fs/xfs/xfs_mount.c
@@ -0,0 +1,2567 @@
+/*
+ * Copyright (c) 2000-2005 Silicon Graphics, Inc.
+ * All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write the Free Software Foundation,
+ * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_types.h"
+#include "xfs_bit.h"
+#include "xfs_log.h"
+#include "xfs_inum.h"
+#include "xfs_trans.h"
+#include "xfs_sb.h"
+#include "xfs_ag.h"
+#include "xfs_dir2.h"
+#include "xfs_mount.h"
+#include "xfs_bmap_btree.h"
+#include "xfs_alloc_btree.h"
+#include "xfs_ialloc_btree.h"
+#include "xfs_dinode.h"
+#include "xfs_inode.h"
+#include "xfs_btree.h"
+#include "xfs_ialloc.h"
+#include "xfs_alloc.h"
+#include "xfs_rtalloc.h"
+#include "xfs_bmap.h"
+#include "xfs_error.h"
+#include "xfs_rw.h"
+#include "xfs_quota.h"
+#include "xfs_fsops.h"
+#include "xfs_utils.h"
+#include "xfs_trace.h"
+
+
+#ifdef HAVE_PERCPU_SB
+STATIC void	xfs_icsb_balance_counter(xfs_mount_t *, xfs_sb_field_t,
+						int);
+STATIC void	xfs_icsb_balance_counter_locked(xfs_mount_t *, xfs_sb_field_t,
+						int);
+STATIC void	xfs_icsb_disable_counter(xfs_mount_t *, xfs_sb_field_t);
+#else
+
+#define xfs_icsb_balance_counter(mp, a, b)		do { } while (0)
+#define xfs_icsb_balance_counter_locked(mp, a, b)	do { } while (0)
+#endif
+
+static const struct {
+	short offset;
+	short type;	/* 0 = integer
+			 * 1 = binary / string (no translation)
+			 */
+} xfs_sb_info[] = {
+    { offsetof(xfs_sb_t, sb_magicnum),   0 },
+    { offsetof(xfs_sb_t, sb_blocksize),  0 },
+    { offsetof(xfs_sb_t, sb_dblocks),    0 },
+    { offsetof(xfs_sb_t, sb_rblocks),    0 },
+    { offsetof(xfs_sb_t, sb_rextents),   0 },
+    { offsetof(xfs_sb_t, sb_uuid),       1 },
+    { offsetof(xfs_sb_t, sb_logstart),   0 },
+    { offsetof(xfs_sb_t, sb_rootino),    0 },
+    { offsetof(xfs_sb_t, sb_rbmino),     0 },
+    { offsetof(xfs_sb_t, sb_rsumino),    0 },
+    { offsetof(xfs_sb_t, sb_rextsize),   0 },
+    { offsetof(xfs_sb_t, sb_agblocks),   0 },
+    { offsetof(xfs_sb_t, sb_agcount),    0 },
+    { offsetof(xfs_sb_t, sb_rbmblocks),  0 },
+    { offsetof(xfs_sb_t, sb_logblocks),  0 },
+    { offsetof(xfs_sb_t, sb_versionnum), 0 },
+    { offsetof(xfs_sb_t, sb_sectsize),   0 },
+    { offsetof(xfs_sb_t, sb_inodesize),  0 },
+    { offsetof(xfs_sb_t, sb_inopblock),  0 },
+    { offsetof(xfs_sb_t, sb_fname[0]),   1 },
+    { offsetof(xfs_sb_t, sb_blocklog),   0 },
+    { offsetof(xfs_sb_t, sb_sectlog),    0 },
+    { offsetof(xfs_sb_t, sb_inodelog),   0 },
+    { offsetof(xfs_sb_t, sb_inopblog),   0 },
+    { offsetof(xfs_sb_t, sb_agblklog),   0 },
+    { offsetof(xfs_sb_t, sb_rextslog),   0 },
+    { offsetof(xfs_sb_t, sb_inprogress), 0 },
+    { offsetof(xfs_sb_t, sb_imax_pct),   0 },
+    { offsetof(xfs_sb_t, sb_icount),     0 },
+    { offsetof(xfs_sb_t, sb_ifree),      0 },
+    { offsetof(xfs_sb_t, sb_fdblocks),   0 },
+    { offsetof(xfs_sb_t, sb_frextents),  0 },
+    { offsetof(xfs_sb_t, sb_uquotino),   0 },
+    { offsetof(xfs_sb_t, sb_gquotino),   0 },
+    { offsetof(xfs_sb_t, sb_qflags),     0 },
+    { offsetof(xfs_sb_t, sb_flags),      0 },
+    { offsetof(xfs_sb_t, sb_shared_vn),  0 },
+    { offsetof(xfs_sb_t, sb_inoalignmt), 0 },
+    { offsetof(xfs_sb_t, sb_unit),	 0 },
+    { offsetof(xfs_sb_t, sb_width),	 0 },
+    { offsetof(xfs_sb_t, sb_dirblklog),	 0 },
+    { offsetof(xfs_sb_t, sb_logsectlog), 0 },
+    { offsetof(xfs_sb_t, sb_logsectsize),0 },
+    { offsetof(xfs_sb_t, sb_logsunit),	 0 },
+    { offsetof(xfs_sb_t, sb_features2),	 0 },
+    { offsetof(xfs_sb_t, sb_bad_features2), 0 },
+    { sizeof(xfs_sb_t),			 0 }
+};
+
+static DEFINE_MUTEX(xfs_uuid_table_mutex);
+static int xfs_uuid_table_size;
+static uuid_t *xfs_uuid_table;
+
+/*
+ * See if the UUID is unique among mounted XFS filesystems.
+ * Mount fails if UUID is nil or a FS with the same UUID is already mounted.
+ */
+STATIC int
+xfs_uuid_mount(
+	struct xfs_mount	*mp)
+{
+	uuid_t			*uuid = &mp->m_sb.sb_uuid;
+	int			hole, i;
+
+	if (mp->m_flags & XFS_MOUNT_NOUUID)
+		return 0;
+
+	if (uuid_is_nil(uuid)) {
+		xfs_warn(mp, "Filesystem has nil UUID - can't mount");
+		return XFS_ERROR(EINVAL);
+	}
+
+	mutex_lock(&xfs_uuid_table_mutex);
+	for (i = 0, hole = -1; i < xfs_uuid_table_size; i++) {
+		if (uuid_is_nil(&xfs_uuid_table[i])) {
+			hole = i;
+			continue;
+		}
+		if (uuid_equal(uuid, &xfs_uuid_table[i]))
+			goto out_duplicate;
+	}
+
+	if (hole < 0) {
+		xfs_uuid_table = kmem_realloc(xfs_uuid_table,
+			(xfs_uuid_table_size + 1) * sizeof(*xfs_uuid_table),
+			xfs_uuid_table_size  * sizeof(*xfs_uuid_table),
+			KM_SLEEP);
+		hole = xfs_uuid_table_size++;
+	}
+	xfs_uuid_table[hole] = *uuid;
+	mutex_unlock(&xfs_uuid_table_mutex);
+
+	return 0;
+
+ out_duplicate:
+	mutex_unlock(&xfs_uuid_table_mutex);
+	xfs_warn(mp, "Filesystem has duplicate UUID %pU - can't mount", uuid);
+	return XFS_ERROR(EINVAL);
+}
+
+STATIC void
+xfs_uuid_unmount(
+	struct xfs_mount	*mp)
+{
+	uuid_t			*uuid = &mp->m_sb.sb_uuid;
+	int			i;
+
+	if (mp->m_flags & XFS_MOUNT_NOUUID)
+		return;
+
+	mutex_lock(&xfs_uuid_table_mutex);
+	for (i = 0; i < xfs_uuid_table_size; i++) {
+		if (uuid_is_nil(&xfs_uuid_table[i]))
+			continue;
+		if (!uuid_equal(uuid, &xfs_uuid_table[i]))
+			continue;
+		memset(&xfs_uuid_table[i], 0, sizeof(uuid_t));
+		break;
+	}
+	ASSERT(i < xfs_uuid_table_size);
+	mutex_unlock(&xfs_uuid_table_mutex);
+}
+
+
+/*
+ * Reference counting access wrappers to the perag structures.
+ * Because we never free per-ag structures, the only thing we
+ * have to protect against changes is the tree structure itself.
+ */
+struct xfs_perag *
+xfs_perag_get(struct xfs_mount *mp, xfs_agnumber_t agno)
+{
+	struct xfs_perag	*pag;
+	int			ref = 0;
+
+	rcu_read_lock();
+	pag = radix_tree_lookup(&mp->m_perag_tree, agno);
+	if (pag) {
+		ASSERT(atomic_read(&pag->pag_ref) >= 0);
+		ref = atomic_inc_return(&pag->pag_ref);
+	}
+	rcu_read_unlock();
+	trace_xfs_perag_get(mp, agno, ref, _RET_IP_);
+	return pag;
+}
+
+/*
+ * search from @first to find the next perag with the given tag set.
+ */
+struct xfs_perag *
+xfs_perag_get_tag(
+	struct xfs_mount	*mp,
+	xfs_agnumber_t		first,
+	int			tag)
+{
+	struct xfs_perag	*pag;
+	int			found;
+	int			ref;
+
+	rcu_read_lock();
+	found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
+					(void **)&pag, first, 1, tag);
+	if (found <= 0) {
+		rcu_read_unlock();
+		return NULL;
+	}
+	ref = atomic_inc_return(&pag->pag_ref);
+	rcu_read_unlock();
+	trace_xfs_perag_get_tag(mp, pag->pag_agno, ref, _RET_IP_);
+	return pag;
+}
+
+void
+xfs_perag_put(struct xfs_perag *pag)
+{
+	int	ref;
+
+	ASSERT(atomic_read(&pag->pag_ref) > 0);
+	ref = atomic_dec_return(&pag->pag_ref);
+	trace_xfs_perag_put(pag->pag_mount, pag->pag_agno, ref, _RET_IP_);
+}
+
+STATIC void
+__xfs_free_perag(
+	struct rcu_head	*head)
+{
+	struct xfs_perag *pag = container_of(head, struct xfs_perag, rcu_head);
+
+	ASSERT(atomic_read(&pag->pag_ref) == 0);
+	kmem_free(pag);
+}
+
+/*
+ * Free up the per-ag resources associated with the mount structure.
+ */
+STATIC void
+xfs_free_perag(
+	xfs_mount_t	*mp)
+{
+	xfs_agnumber_t	agno;
+	struct xfs_perag *pag;
+
+	for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) {
+		spin_lock(&mp->m_perag_lock);
+		pag = radix_tree_delete(&mp->m_perag_tree, agno);
+		spin_unlock(&mp->m_perag_lock);
+		ASSERT(pag);
+		ASSERT(atomic_read(&pag->pag_ref) == 0);
+		call_rcu(&pag->rcu_head, __xfs_free_perag);
+	}
+}
+
+/*
+ * Check size of device based on the (data/realtime) block count.
+ * Note: this check is used by the growfs code as well as mount.
+ */
+int
+xfs_sb_validate_fsb_count(
+	xfs_sb_t	*sbp,
+	__uint64_t	nblocks)
+{
+	ASSERT(PAGE_SHIFT >= sbp->sb_blocklog);
+	ASSERT(sbp->sb_blocklog >= BBSHIFT);
+
+#if XFS_BIG_BLKNOS     /* Limited by ULONG_MAX of page cache index */
+	if (nblocks >> (PAGE_CACHE_SHIFT - sbp->sb_blocklog) > ULONG_MAX)
+		return EFBIG;
+#else                  /* Limited by UINT_MAX of sectors */
+	if (nblocks << (sbp->sb_blocklog - BBSHIFT) > UINT_MAX)
+		return EFBIG;
+#endif
+	return 0;
+}
+
+/*
+ * Check the validity of the SB found.
+ */
+STATIC int
+xfs_mount_validate_sb(
+	xfs_mount_t	*mp,
+	xfs_sb_t	*sbp,
+	int		flags)
+{
+	int		loud = !(flags & XFS_MFSI_QUIET);
+
+	/*
+	 * If the log device and data device have the
+	 * same device number, the log is internal.
+	 * Consequently, the sb_logstart should be non-zero.  If
+	 * we have a zero sb_logstart in this case, we may be trying to mount
+	 * a volume filesystem in a non-volume manner.
+	 */
+	if (sbp->sb_magicnum != XFS_SB_MAGIC) {
+		if (loud)
+			xfs_warn(mp, "bad magic number");
+		return XFS_ERROR(EWRONGFS);
+	}
+
+	if (!xfs_sb_good_version(sbp)) {
+		if (loud)
+			xfs_warn(mp, "bad version");
+		return XFS_ERROR(EWRONGFS);
+	}
+
+	if (unlikely(
+	    sbp->sb_logstart == 0 && mp->m_logdev_targp == mp->m_ddev_targp)) {
+		if (loud)
+			xfs_warn(mp,
+		"filesystem is marked as having an external log; "
+		"specify logdev on the mount command line.");
+		return XFS_ERROR(EINVAL);
+	}
+
+	if (unlikely(
+	    sbp->sb_logstart != 0 && mp->m_logdev_targp != mp->m_ddev_targp)) {
+		if (loud)
+			xfs_warn(mp,
+		"filesystem is marked as having an internal log; "
+		"do not specify logdev on the mount command line.");
+		return XFS_ERROR(EINVAL);
+	}
+
+	/*
+	 * More sanity checking.  Most of these were stolen directly from
+	 * xfs_repair.
+	 */
+	if (unlikely(
+	    sbp->sb_agcount <= 0					||
+	    sbp->sb_sectsize < XFS_MIN_SECTORSIZE			||
+	    sbp->sb_sectsize > XFS_MAX_SECTORSIZE			||
+	    sbp->sb_sectlog < XFS_MIN_SECTORSIZE_LOG			||
+	    sbp->sb_sectlog > XFS_MAX_SECTORSIZE_LOG			||
+	    sbp->sb_sectsize != (1 << sbp->sb_sectlog)			||
+	    sbp->sb_blocksize < XFS_MIN_BLOCKSIZE			||
+	    sbp->sb_blocksize > XFS_MAX_BLOCKSIZE			||
+	    sbp->sb_blocklog < XFS_MIN_BLOCKSIZE_LOG			||
+	    sbp->sb_blocklog > XFS_MAX_BLOCKSIZE_LOG			||
+	    sbp->sb_blocksize != (1 << sbp->sb_blocklog)		||
+	    sbp->sb_inodesize < XFS_DINODE_MIN_SIZE			||
+	    sbp->sb_inodesize > XFS_DINODE_MAX_SIZE			||
+	    sbp->sb_inodelog < XFS_DINODE_MIN_LOG			||
+	    sbp->sb_inodelog > XFS_DINODE_MAX_LOG			||
+	    sbp->sb_inodesize != (1 << sbp->sb_inodelog)		||
+	    (sbp->sb_blocklog - sbp->sb_inodelog != sbp->sb_inopblog)	||
+	    (sbp->sb_rextsize * sbp->sb_blocksize > XFS_MAX_RTEXTSIZE)	||
+	    (sbp->sb_rextsize * sbp->sb_blocksize < XFS_MIN_RTEXTSIZE)	||
+	    (sbp->sb_imax_pct > 100 /* zero sb_imax_pct is valid */)	||
+	    sbp->sb_dblocks == 0					||
+	    sbp->sb_dblocks > XFS_MAX_DBLOCKS(sbp)			||
+	    sbp->sb_dblocks < XFS_MIN_DBLOCKS(sbp))) {
+		if (loud)
+			XFS_CORRUPTION_ERROR("SB sanity check failed",
+				XFS_ERRLEVEL_LOW, mp, sbp);
+		return XFS_ERROR(EFSCORRUPTED);
+	}
+
+	/*
+	 * Until this is fixed only page-sized or smaller data blocks work.
+	 */
+	if (unlikely(sbp->sb_blocksize > PAGE_SIZE)) {
+		if (loud) {
+			xfs_warn(mp,
+		"File system with blocksize %d bytes. "
+		"Only pagesize (%ld) or less will currently work.",
+				sbp->sb_blocksize, PAGE_SIZE);
+		}
+		return XFS_ERROR(ENOSYS);
+	}
+
+	/*
+	 * Currently only very few inode sizes are supported.
+	 */
+	switch (sbp->sb_inodesize) {
+	case 256:
+	case 512:
+	case 1024:
+	case 2048:
+		break;
+	default:
+		if (loud)
+			xfs_warn(mp, "inode size of %d bytes not supported",
+				sbp->sb_inodesize);
+		return XFS_ERROR(ENOSYS);
+	}
+
+	if (xfs_sb_validate_fsb_count(sbp, sbp->sb_dblocks) ||
+	    xfs_sb_validate_fsb_count(sbp, sbp->sb_rblocks)) {
+		if (loud)
+			xfs_warn(mp,
+		"file system too large to be mounted on this system.");
+		return XFS_ERROR(EFBIG);
+	}
+
+	if (unlikely(sbp->sb_inprogress)) {
+		if (loud)
+			xfs_warn(mp, "file system busy");
+		return XFS_ERROR(EFSCORRUPTED);
+	}
+
+	/*
+	 * Version 1 directory format has never worked on Linux.
+	 */
+	if (unlikely(!xfs_sb_version_hasdirv2(sbp))) {
+		if (loud)
+			xfs_warn(mp,
+				"file system using version 1 directory format");
+		return XFS_ERROR(ENOSYS);
+	}
+
+	return 0;
+}
+
+int
+xfs_initialize_perag(
+	xfs_mount_t	*mp,
+	xfs_agnumber_t	agcount,
+	xfs_agnumber_t	*maxagi)
+{
+	xfs_agnumber_t	index, max_metadata;
+	xfs_agnumber_t	first_initialised = 0;
+	xfs_perag_t	*pag;
+	xfs_agino_t	agino;
+	xfs_ino_t	ino;
+	xfs_sb_t	*sbp = &mp->m_sb;
+	int		error = -ENOMEM;
+
+	/*
+	 * Walk the current per-ag tree so we don't try to initialise AGs
+	 * that already exist (growfs case). Allocate and insert all the
+	 * AGs we don't find ready for initialisation.
+	 */
+	for (index = 0; index < agcount; index++) {
+		pag = xfs_perag_get(mp, index);
+		if (pag) {
+			xfs_perag_put(pag);
+			continue;
+		}
+		if (!first_initialised)
+			first_initialised = index;
+
+		pag = kmem_zalloc(sizeof(*pag), KM_MAYFAIL);
+		if (!pag)
+			goto out_unwind;
+		pag->pag_agno = index;
+		pag->pag_mount = mp;
+		spin_lock_init(&pag->pag_ici_lock);
+		mutex_init(&pag->pag_ici_reclaim_lock);
+		INIT_RADIX_TREE(&pag->pag_ici_root, GFP_ATOMIC);
+		spin_lock_init(&pag->pag_buf_lock);
+		pag->pag_buf_tree = RB_ROOT;
+
+		if (radix_tree_preload(GFP_NOFS))
+			goto out_unwind;
+
+		spin_lock(&mp->m_perag_lock);
+		if (radix_tree_insert(&mp->m_perag_tree, index, pag)) {
+			BUG();
+			spin_unlock(&mp->m_perag_lock);
+			radix_tree_preload_end();
+			error = -EEXIST;
+			goto out_unwind;
+		}
+		spin_unlock(&mp->m_perag_lock);
+		radix_tree_preload_end();
+	}
+
+	/*
+	 * If we mount with the inode64 option, or no inode overflows
+	 * the legacy 32-bit address space clear the inode32 option.
+	 */
+	agino = XFS_OFFBNO_TO_AGINO(mp, sbp->sb_agblocks - 1, 0);
+	ino = XFS_AGINO_TO_INO(mp, agcount - 1, agino);
+
+	if ((mp->m_flags & XFS_MOUNT_SMALL_INUMS) && ino > XFS_MAXINUMBER_32)
+		mp->m_flags |= XFS_MOUNT_32BITINODES;
+	else
+		mp->m_flags &= ~XFS_MOUNT_32BITINODES;
+
+	if (mp->m_flags & XFS_MOUNT_32BITINODES) {
+		/*
+		 * Calculate how much should be reserved for inodes to meet
+		 * the max inode percentage.
+		 */
+		if (mp->m_maxicount) {
+			__uint64_t	icount;
+
+			icount = sbp->sb_dblocks * sbp->sb_imax_pct;
+			do_div(icount, 100);
+			icount += sbp->sb_agblocks - 1;
+			do_div(icount, sbp->sb_agblocks);
+			max_metadata = icount;
+		} else {
+			max_metadata = agcount;
+		}
+
+		for (index = 0; index < agcount; index++) {
+			ino = XFS_AGINO_TO_INO(mp, index, agino);
+			if (ino > XFS_MAXINUMBER_32) {
+				index++;
+				break;
+			}
+
+			pag = xfs_perag_get(mp, index);
+			pag->pagi_inodeok = 1;
+			if (index < max_metadata)
+				pag->pagf_metadata = 1;
+			xfs_perag_put(pag);
+		}
+	} else {
+		for (index = 0; index < agcount; index++) {
+			pag = xfs_perag_get(mp, index);
+			pag->pagi_inodeok = 1;
+			xfs_perag_put(pag);
+		}
+	}
+
+	if (maxagi)
+		*maxagi = index;
+	return 0;
+
+out_unwind:
+	kmem_free(pag);
+	for (; index > first_initialised; index--) {
+		pag = radix_tree_delete(&mp->m_perag_tree, index);
+		kmem_free(pag);
+	}
+	return error;
+}
+
+void
+xfs_sb_from_disk(
+	struct xfs_mount	*mp,
+	xfs_dsb_t	*from)
+{
+	struct xfs_sb *to = &mp->m_sb;
+
+	to->sb_magicnum = be32_to_cpu(from->sb_magicnum);
+	to->sb_blocksize = be32_to_cpu(from->sb_blocksize);
+	to->sb_dblocks = be64_to_cpu(from->sb_dblocks);
+	to->sb_rblocks = be64_to_cpu(from->sb_rblocks);
+	to->sb_rextents = be64_to_cpu(from->sb_rextents);
+	memcpy(&to->sb_uuid, &from->sb_uuid, sizeof(to->sb_uuid));
+	to->sb_logstart = be64_to_cpu(from->sb_logstart);
+	to->sb_rootino = be64_to_cpu(from->sb_rootino);
+	to->sb_rbmino = be64_to_cpu(from->sb_rbmino);
+	to->sb_rsumino = be64_to_cpu(from->sb_rsumino);
+	to->sb_rextsize = be32_to_cpu(from->sb_rextsize);
+	to->sb_agblocks = be32_to_cpu(from->sb_agblocks);
+	to->sb_agcount = be32_to_cpu(from->sb_agcount);
+	to->sb_rbmblocks = be32_to_cpu(from->sb_rbmblocks);
+	to->sb_logblocks = be32_to_cpu(from->sb_logblocks);
+	to->sb_versionnum = be16_to_cpu(from->sb_versionnum);
+	to->sb_sectsize = be16_to_cpu(from->sb_sectsize);
+	to->sb_inodesize = be16_to_cpu(from->sb_inodesize);
+	to->sb_inopblock = be16_to_cpu(from->sb_inopblock);
+	memcpy(&to->sb_fname, &from->sb_fname, sizeof(to->sb_fname));
+	to->sb_blocklog = from->sb_blocklog;
+	to->sb_sectlog = from->sb_sectlog;
+	to->sb_inodelog = from->sb_inodelog;
+	to->sb_inopblog = from->sb_inopblog;
+	to->sb_agblklog = from->sb_agblklog;
+	to->sb_rextslog = from->sb_rextslog;
+	to->sb_inprogress = from->sb_inprogress;
+	to->sb_imax_pct = from->sb_imax_pct;
+	to->sb_icount = be64_to_cpu(from->sb_icount);
+	to->sb_ifree = be64_to_cpu(from->sb_ifree);
+	to->sb_fdblocks = be64_to_cpu(from->sb_fdblocks);
+	to->sb_frextents = be64_to_cpu(from->sb_frextents);
+	to->sb_uquotino = be64_to_cpu(from->sb_uquotino);
+	to->sb_gquotino = be64_to_cpu(from->sb_gquotino);
+	to->sb_qflags = be16_to_cpu(from->sb_qflags);
+	to->sb_flags = from->sb_flags;
+	to->sb_shared_vn = from->sb_shared_vn;
+	to->sb_inoalignmt = be32_to_cpu(from->sb_inoalignmt);
+	to->sb_unit = be32_to_cpu(from->sb_unit);
+	to->sb_width = be32_to_cpu(from->sb_width);
+	to->sb_dirblklog = from->sb_dirblklog;
+	to->sb_logsectlog = from->sb_logsectlog;
+	to->sb_logsectsize = be16_to_cpu(from->sb_logsectsize);
+	to->sb_logsunit = be32_to_cpu(from->sb_logsunit);
+	to->sb_features2 = be32_to_cpu(from->sb_features2);
+	to->sb_bad_features2 = be32_to_cpu(from->sb_bad_features2);
+}
+
+/*
+ * Copy in core superblock to ondisk one.
+ *
+ * The fields argument is mask of superblock fields to copy.
+ */
+void
+xfs_sb_to_disk(
+	xfs_dsb_t	*to,
+	xfs_sb_t	*from,
+	__int64_t	fields)
+{
+	xfs_caddr_t	to_ptr = (xfs_caddr_t)to;
+	xfs_caddr_t	from_ptr = (xfs_caddr_t)from;
+	xfs_sb_field_t	f;
+	int		first;
+	int		size;
+
+	ASSERT(fields);
+	if (!fields)
+		return;
+
+	while (fields) {
+		f = (xfs_sb_field_t)xfs_lowbit64((__uint64_t)fields);
+		first = xfs_sb_info[f].offset;
+		size = xfs_sb_info[f + 1].offset - first;
+
+		ASSERT(xfs_sb_info[f].type == 0 || xfs_sb_info[f].type == 1);
+
+		if (size == 1 || xfs_sb_info[f].type == 1) {
+			memcpy(to_ptr + first, from_ptr + first, size);
+		} else {
+			switch (size) {
+			case 2:
+				*(__be16 *)(to_ptr + first) =
+					cpu_to_be16(*(__u16 *)(from_ptr + first));
+				break;
+			case 4:
+				*(__be32 *)(to_ptr + first) =
+					cpu_to_be32(*(__u32 *)(from_ptr + first));
+				break;
+			case 8:
+				*(__be64 *)(to_ptr + first) =
+					cpu_to_be64(*(__u64 *)(from_ptr + first));
+				break;
+			default:
+				ASSERT(0);
+			}
+		}
+
+		fields &= ~(1LL << f);
+	}
+}
+
+/*
+ * xfs_readsb
+ *
+ * Does the initial read of the superblock.
+ */
+int
+xfs_readsb(xfs_mount_t *mp, int flags)
+{
+	unsigned int	sector_size;
+	xfs_buf_t	*bp;
+	int		error;
+	int		loud = !(flags & XFS_MFSI_QUIET);
+
+	ASSERT(mp->m_sb_bp == NULL);
+	ASSERT(mp->m_ddev_targp != NULL);
+
+	/*
+	 * Allocate a (locked) buffer to hold the superblock.
+	 * This will be kept around at all times to optimize
+	 * access to the superblock.
+	 */
+	sector_size = xfs_getsize_buftarg(mp->m_ddev_targp);
+
+reread:
+	bp = xfs_buf_read_uncached(mp, mp->m_ddev_targp,
+					XFS_SB_DADDR, sector_size, 0);
+	if (!bp) {
+		if (loud)
+			xfs_warn(mp, "SB buffer read failed");
+		return EIO;
+	}
+
+	/*
+	 * Initialize the mount structure from the superblock.
+	 * But first do some basic consistency checking.
+	 */
+	xfs_sb_from_disk(mp, XFS_BUF_TO_SBP(bp));
+	error = xfs_mount_validate_sb(mp, &(mp->m_sb), flags);
+	if (error) {
+		if (loud)
+			xfs_warn(mp, "SB validate failed");
+		goto release_buf;
+	}
+
+	/*
+	 * We must be able to do sector-sized and sector-aligned IO.
+	 */
+	if (sector_size > mp->m_sb.sb_sectsize) {
+		if (loud)
+			xfs_warn(mp, "device supports %u byte sectors (not %u)",
+				sector_size, mp->m_sb.sb_sectsize);
+		error = ENOSYS;
+		goto release_buf;
+	}
+
+	/*
+	 * If device sector size is smaller than the superblock size,
+	 * re-read the superblock so the buffer is correctly sized.
+	 */
+	if (sector_size < mp->m_sb.sb_sectsize) {
+		xfs_buf_relse(bp);
+		sector_size = mp->m_sb.sb_sectsize;
+		goto reread;
+	}
+
+	/* Initialize per-cpu counters */
+	xfs_icsb_reinit_counters(mp);
+
+	mp->m_sb_bp = bp;
+	xfs_buf_unlock(bp);
+	return 0;
+
+release_buf:
+	xfs_buf_relse(bp);
+	return error;
+}
+
+
+/*
+ * xfs_mount_common
+ *
+ * Mount initialization code establishing various mount
+ * fields from the superblock associated with the given
+ * mount structure
+ */
+STATIC void
+xfs_mount_common(xfs_mount_t *mp, xfs_sb_t *sbp)
+{
+	mp->m_agfrotor = mp->m_agirotor = 0;
+	spin_lock_init(&mp->m_agirotor_lock);
+	mp->m_maxagi = mp->m_sb.sb_agcount;
+	mp->m_blkbit_log = sbp->sb_blocklog + XFS_NBBYLOG;
+	mp->m_blkbb_log = sbp->sb_blocklog - BBSHIFT;
+	mp->m_sectbb_log = sbp->sb_sectlog - BBSHIFT;
+	mp->m_agno_log = xfs_highbit32(sbp->sb_agcount - 1) + 1;
+	mp->m_agino_log = sbp->sb_inopblog + sbp->sb_agblklog;
+	mp->m_blockmask = sbp->sb_blocksize - 1;
+	mp->m_blockwsize = sbp->sb_blocksize >> XFS_WORDLOG;
+	mp->m_blockwmask = mp->m_blockwsize - 1;
+
+	mp->m_alloc_mxr[0] = xfs_allocbt_maxrecs(mp, sbp->sb_blocksize, 1);
+	mp->m_alloc_mxr[1] = xfs_allocbt_maxrecs(mp, sbp->sb_blocksize, 0);
+	mp->m_alloc_mnr[0] = mp->m_alloc_mxr[0] / 2;
+	mp->m_alloc_mnr[1] = mp->m_alloc_mxr[1] / 2;
+
+	mp->m_inobt_mxr[0] = xfs_inobt_maxrecs(mp, sbp->sb_blocksize, 1);
+	mp->m_inobt_mxr[1] = xfs_inobt_maxrecs(mp, sbp->sb_blocksize, 0);
+	mp->m_inobt_mnr[0] = mp->m_inobt_mxr[0] / 2;
+	mp->m_inobt_mnr[1] = mp->m_inobt_mxr[1] / 2;
+
+	mp->m_bmap_dmxr[0] = xfs_bmbt_maxrecs(mp, sbp->sb_blocksize, 1);
+	mp->m_bmap_dmxr[1] = xfs_bmbt_maxrecs(mp, sbp->sb_blocksize, 0);
+	mp->m_bmap_dmnr[0] = mp->m_bmap_dmxr[0] / 2;
+	mp->m_bmap_dmnr[1] = mp->m_bmap_dmxr[1] / 2;
+
+	mp->m_bsize = XFS_FSB_TO_BB(mp, 1);
+	mp->m_ialloc_inos = (int)MAX((__uint16_t)XFS_INODES_PER_CHUNK,
+					sbp->sb_inopblock);
+	mp->m_ialloc_blks = mp->m_ialloc_inos >> sbp->sb_inopblog;
+}
+
+/*
+ * xfs_initialize_perag_data
+ *
+ * Read in each per-ag structure so we can count up the number of
+ * allocated inodes, free inodes and used filesystem blocks as this
+ * information is no longer persistent in the superblock. Once we have
+ * this information, write it into the in-core superblock structure.
+ */
+STATIC int
+xfs_initialize_perag_data(xfs_mount_t *mp, xfs_agnumber_t agcount)
+{
+	xfs_agnumber_t	index;
+	xfs_perag_t	*pag;
+	xfs_sb_t	*sbp = &mp->m_sb;
+	uint64_t	ifree = 0;
+	uint64_t	ialloc = 0;
+	uint64_t	bfree = 0;
+	uint64_t	bfreelst = 0;
+	uint64_t	btree = 0;
+	int		error;
+
+	for (index = 0; index < agcount; index++) {
+		/*
+		 * read the agf, then the agi. This gets us
+		 * all the information we need and populates the
+		 * per-ag structures for us.
+		 */
+		error = xfs_alloc_pagf_init(mp, NULL, index, 0);
+		if (error)
+			return error;
+
+		error = xfs_ialloc_pagi_init(mp, NULL, index);
+		if (error)
+			return error;
+		pag = xfs_perag_get(mp, index);
+		ifree += pag->pagi_freecount;
+		ialloc += pag->pagi_count;
+		bfree += pag->pagf_freeblks;
+		bfreelst += pag->pagf_flcount;
+		btree += pag->pagf_btreeblks;
+		xfs_perag_put(pag);
+	}
+	/*
+	 * Overwrite incore superblock counters with just-read data
+	 */
+	spin_lock(&mp->m_sb_lock);
+	sbp->sb_ifree = ifree;
+	sbp->sb_icount = ialloc;
+	sbp->sb_fdblocks = bfree + bfreelst + btree;
+	spin_unlock(&mp->m_sb_lock);
+
+	/* Fixup the per-cpu counters as well. */
+	xfs_icsb_reinit_counters(mp);
+
+	return 0;
+}
+
+/*
+ * Update alignment values based on mount options and sb values
+ */
+STATIC int
+xfs_update_alignment(xfs_mount_t *mp)
+{
+	xfs_sb_t	*sbp = &(mp->m_sb);
+
+	if (mp->m_dalign) {
+		/*
+		 * If stripe unit and stripe width are not multiples
+		 * of the fs blocksize turn off alignment.
+		 */
+		if ((BBTOB(mp->m_dalign) & mp->m_blockmask) ||
+		    (BBTOB(mp->m_swidth) & mp->m_blockmask)) {
+			if (mp->m_flags & XFS_MOUNT_RETERR) {
+				xfs_warn(mp, "alignment check failed: "
+					 "(sunit/swidth vs. blocksize)");
+				return XFS_ERROR(EINVAL);
+			}
+			mp->m_dalign = mp->m_swidth = 0;
+		} else {
+			/*
+			 * Convert the stripe unit and width to FSBs.
+			 */
+			mp->m_dalign = XFS_BB_TO_FSBT(mp, mp->m_dalign);
+			if (mp->m_dalign && (sbp->sb_agblocks % mp->m_dalign)) {
+				if (mp->m_flags & XFS_MOUNT_RETERR) {
+					xfs_warn(mp, "alignment check failed: "
+						 "(sunit/swidth vs. ag size)");
+					return XFS_ERROR(EINVAL);
+				}
+				xfs_warn(mp,
+		"stripe alignment turned off: sunit(%d)/swidth(%d) "
+		"incompatible with agsize(%d)",
+					mp->m_dalign, mp->m_swidth,
+					sbp->sb_agblocks);
+
+				mp->m_dalign = 0;
+				mp->m_swidth = 0;
+			} else if (mp->m_dalign) {
+				mp->m_swidth = XFS_BB_TO_FSBT(mp, mp->m_swidth);
+			} else {
+				if (mp->m_flags & XFS_MOUNT_RETERR) {
+					xfs_warn(mp, "alignment check failed: "
+						"sunit(%d) less than bsize(%d)",
+						mp->m_dalign,
+						mp->m_blockmask +1);
+					return XFS_ERROR(EINVAL);
+				}
+				mp->m_swidth = 0;
+			}
+		}
+
+		/*
+		 * Update superblock with new values
+		 * and log changes
+		 */
+		if (xfs_sb_version_hasdalign(sbp)) {
+			if (sbp->sb_unit != mp->m_dalign) {
+				sbp->sb_unit = mp->m_dalign;
+				mp->m_update_flags |= XFS_SB_UNIT;
+			}
+			if (sbp->sb_width != mp->m_swidth) {
+				sbp->sb_width = mp->m_swidth;
+				mp->m_update_flags |= XFS_SB_WIDTH;
+			}
+		}
+	} else if ((mp->m_flags & XFS_MOUNT_NOALIGN) != XFS_MOUNT_NOALIGN &&
+		    xfs_sb_version_hasdalign(&mp->m_sb)) {
+			mp->m_dalign = sbp->sb_unit;
+			mp->m_swidth = sbp->sb_width;
+	}
+
+	return 0;
+}
+
+/*
+ * Set the maximum inode count for this filesystem
+ */
+STATIC void
+xfs_set_maxicount(xfs_mount_t *mp)
+{
+	xfs_sb_t	*sbp = &(mp->m_sb);
+	__uint64_t	icount;
+
+	if (sbp->sb_imax_pct) {
+		/*
+		 * Make sure the maximum inode count is a multiple
+		 * of the units we allocate inodes in.
+		 */
+		icount = sbp->sb_dblocks * sbp->sb_imax_pct;
+		do_div(icount, 100);
+		do_div(icount, mp->m_ialloc_blks);
+		mp->m_maxicount = (icount * mp->m_ialloc_blks)  <<
+				   sbp->sb_inopblog;
+	} else {
+		mp->m_maxicount = 0;
+	}
+}
+
+/*
+ * Set the default minimum read and write sizes unless
+ * already specified in a mount option.
+ * We use smaller I/O sizes when the file system
+ * is being used for NFS service (wsync mount option).
+ */
+STATIC void
+xfs_set_rw_sizes(xfs_mount_t *mp)
+{
+	xfs_sb_t	*sbp = &(mp->m_sb);
+	int		readio_log, writeio_log;
+
+	if (!(mp->m_flags & XFS_MOUNT_DFLT_IOSIZE)) {
+		if (mp->m_flags & XFS_MOUNT_WSYNC) {
+			readio_log = XFS_WSYNC_READIO_LOG;
+			writeio_log = XFS_WSYNC_WRITEIO_LOG;
+		} else {
+			readio_log = XFS_READIO_LOG_LARGE;
+			writeio_log = XFS_WRITEIO_LOG_LARGE;
+		}
+	} else {
+		readio_log = mp->m_readio_log;
+		writeio_log = mp->m_writeio_log;
+	}
+
+	if (sbp->sb_blocklog > readio_log) {
+		mp->m_readio_log = sbp->sb_blocklog;
+	} else {
+		mp->m_readio_log = readio_log;
+	}
+	mp->m_readio_blocks = 1 << (mp->m_readio_log - sbp->sb_blocklog);
+	if (sbp->sb_blocklog > writeio_log) {
+		mp->m_writeio_log = sbp->sb_blocklog;
+	} else {
+		mp->m_writeio_log = writeio_log;
+	}
+	mp->m_writeio_blocks = 1 << (mp->m_writeio_log - sbp->sb_blocklog);
+}
+
+/*
+ * precalculate the low space thresholds for dynamic speculative preallocation.
+ */
+void
+xfs_set_low_space_thresholds(
+	struct xfs_mount	*mp)
+{
+	int i;
+
+	for (i = 0; i < XFS_LOWSP_MAX; i++) {
+		__uint64_t space = mp->m_sb.sb_dblocks;
+
+		do_div(space, 100);
+		mp->m_low_space[i] = space * (i + 1);
+	}
+}
+
+
+/*
+ * Set whether we're using inode alignment.
+ */
+STATIC void
+xfs_set_inoalignment(xfs_mount_t *mp)
+{
+	if (xfs_sb_version_hasalign(&mp->m_sb) &&
+	    mp->m_sb.sb_inoalignmt >=
+	    XFS_B_TO_FSBT(mp, mp->m_inode_cluster_size))
+		mp->m_inoalign_mask = mp->m_sb.sb_inoalignmt - 1;
+	else
+		mp->m_inoalign_mask = 0;
+	/*
+	 * If we are using stripe alignment, check whether
+	 * the stripe unit is a multiple of the inode alignment
+	 */
+	if (mp->m_dalign && mp->m_inoalign_mask &&
+	    !(mp->m_dalign & mp->m_inoalign_mask))
+		mp->m_sinoalign = mp->m_dalign;
+	else
+		mp->m_sinoalign = 0;
+}
+
+/*
+ * Check that the data (and log if separate) are an ok size.
+ */
+STATIC int
+xfs_check_sizes(xfs_mount_t *mp)
+{
+	xfs_buf_t	*bp;
+	xfs_daddr_t	d;
+
+	d = (xfs_daddr_t)XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks);
+	if (XFS_BB_TO_FSB(mp, d) != mp->m_sb.sb_dblocks) {
+		xfs_warn(mp, "filesystem size mismatch detected");
+		return XFS_ERROR(EFBIG);
+	}
+	bp = xfs_buf_read_uncached(mp, mp->m_ddev_targp,
+					d - XFS_FSS_TO_BB(mp, 1),
+					BBTOB(XFS_FSS_TO_BB(mp, 1)), 0);
+	if (!bp) {
+		xfs_warn(mp, "last sector read failed");
+		return EIO;
+	}
+	xfs_buf_relse(bp);
+
+	if (mp->m_logdev_targp != mp->m_ddev_targp) {
+		d = (xfs_daddr_t)XFS_FSB_TO_BB(mp, mp->m_sb.sb_logblocks);
+		if (XFS_BB_TO_FSB(mp, d) != mp->m_sb.sb_logblocks) {
+			xfs_warn(mp, "log size mismatch detected");
+			return XFS_ERROR(EFBIG);
+		}
+		bp = xfs_buf_read_uncached(mp, mp->m_logdev_targp,
+					d - XFS_FSB_TO_BB(mp, 1),
+					XFS_FSB_TO_B(mp, 1), 0);
+		if (!bp) {
+			xfs_warn(mp, "log device read failed");
+			return EIO;
+		}
+		xfs_buf_relse(bp);
+	}
+	return 0;
+}
+
+/*
+ * Clear the quotaflags in memory and in the superblock.
+ */
+int
+xfs_mount_reset_sbqflags(
+	struct xfs_mount	*mp)
+{
+	int			error;
+	struct xfs_trans	*tp;
+
+	mp->m_qflags = 0;
+
+	/*
+	 * It is OK to look at sb_qflags here in mount path,
+	 * without m_sb_lock.
+	 */
+	if (mp->m_sb.sb_qflags == 0)
+		return 0;
+	spin_lock(&mp->m_sb_lock);
+	mp->m_sb.sb_qflags = 0;
+	spin_unlock(&mp->m_sb_lock);
+
+	/*
+	 * If the fs is readonly, let the incore superblock run
+	 * with quotas off but don't flush the update out to disk
+	 */
+	if (mp->m_flags & XFS_MOUNT_RDONLY)
+		return 0;
+
+	tp = xfs_trans_alloc(mp, XFS_TRANS_QM_SBCHANGE);
+	error = xfs_trans_reserve(tp, 0, mp->m_sb.sb_sectsize + 128, 0, 0,
+				      XFS_DEFAULT_LOG_COUNT);
+	if (error) {
+		xfs_trans_cancel(tp, 0);
+		xfs_alert(mp, "%s: Superblock update failed!", __func__);
+		return error;
+	}
+
+	xfs_mod_sb(tp, XFS_SB_QFLAGS);
+	return xfs_trans_commit(tp, 0);
+}
+
+__uint64_t
+xfs_default_resblks(xfs_mount_t *mp)
+{
+	__uint64_t resblks;
+
+	/*
+	 * We default to 5% or 8192 fsbs of space reserved, whichever is
+	 * smaller.  This is intended to cover concurrent allocation
+	 * transactions when we initially hit enospc. These each require a 4
+	 * block reservation. Hence by default we cover roughly 2000 concurrent
+	 * allocation reservations.
+	 */
+	resblks = mp->m_sb.sb_dblocks;
+	do_div(resblks, 20);
+	resblks = min_t(__uint64_t, resblks, 8192);
+	return resblks;
+}
+
+/*
+ * This function does the following on an initial mount of a file system:
+ *	- reads the superblock from disk and init the mount struct
+ *	- if we're a 32-bit kernel, do a size check on the superblock
+ *		so we don't mount terabyte filesystems
+ *	- init mount struct realtime fields
+ *	- allocate inode hash table for fs
+ *	- init directory manager
+ *	- perform recovery and init the log manager
+ */
+int
+xfs_mountfs(
+	xfs_mount_t	*mp)
+{
+	xfs_sb_t	*sbp = &(mp->m_sb);
+	xfs_inode_t	*rip;
+	__uint64_t	resblks;
+	uint		quotamount = 0;
+	uint		quotaflags = 0;
+	int		error = 0;
+
+	xfs_mount_common(mp, sbp);
+
+	/*
+	 * Check for a mismatched features2 values.  Older kernels
+	 * read & wrote into the wrong sb offset for sb_features2
+	 * on some platforms due to xfs_sb_t not being 64bit size aligned
+	 * when sb_features2 was added, which made older superblock
+	 * reading/writing routines swap it as a 64-bit value.
+	 *
+	 * For backwards compatibility, we make both slots equal.
+	 *
+	 * If we detect a mismatched field, we OR the set bits into the
+	 * existing features2 field in case it has already been modified; we
+	 * don't want to lose any features.  We then update the bad location
+	 * with the ORed value so that older kernels will see any features2
+	 * flags, and mark the two fields as needing updates once the
+	 * transaction subsystem is online.
+	 */
+	if (xfs_sb_has_mismatched_features2(sbp)) {
+		xfs_warn(mp, "correcting sb_features alignment problem");
+		sbp->sb_features2 |= sbp->sb_bad_features2;
+		sbp->sb_bad_features2 = sbp->sb_features2;
+		mp->m_update_flags |= XFS_SB_FEATURES2 | XFS_SB_BAD_FEATURES2;
+
+		/*
+		 * Re-check for ATTR2 in case it was found in bad_features2
+		 * slot.
+		 */
+		if (xfs_sb_version_hasattr2(&mp->m_sb) &&
+		   !(mp->m_flags & XFS_MOUNT_NOATTR2))
+			mp->m_flags |= XFS_MOUNT_ATTR2;
+	}
+
+	if (xfs_sb_version_hasattr2(&mp->m_sb) &&
+	   (mp->m_flags & XFS_MOUNT_NOATTR2)) {
+		xfs_sb_version_removeattr2(&mp->m_sb);
+		mp->m_update_flags |= XFS_SB_FEATURES2;
+
+		/* update sb_versionnum for the clearing of the morebits */
+		if (!sbp->sb_features2)
+			mp->m_update_flags |= XFS_SB_VERSIONNUM;
+	}
+
+	/*
+	 * Check if sb_agblocks is aligned at stripe boundary
+	 * If sb_agblocks is NOT aligned turn off m_dalign since
+	 * allocator alignment is within an ag, therefore ag has
+	 * to be aligned at stripe boundary.
+	 */
+	error = xfs_update_alignment(mp);
+	if (error)
+		goto out;
+
+	xfs_alloc_compute_maxlevels(mp);
+	xfs_bmap_compute_maxlevels(mp, XFS_DATA_FORK);
+	xfs_bmap_compute_maxlevels(mp, XFS_ATTR_FORK);
+	xfs_ialloc_compute_maxlevels(mp);
+
+	xfs_set_maxicount(mp);
+
+	mp->m_maxioffset = xfs_max_file_offset(sbp->sb_blocklog);
+
+	error = xfs_uuid_mount(mp);
+	if (error)
+		goto out;
+
+	/*
+	 * Set the minimum read and write sizes
+	 */
+	xfs_set_rw_sizes(mp);
+
+	/* set the low space thresholds for dynamic preallocation */
+	xfs_set_low_space_thresholds(mp);
+
+	/*
+	 * Set the inode cluster size.
+	 * This may still be overridden by the file system
+	 * block size if it is larger than the chosen cluster size.
+	 */
+	mp->m_inode_cluster_size = XFS_INODE_BIG_CLUSTER_SIZE;
+
+	/*
+	 * Set inode alignment fields
+	 */
+	xfs_set_inoalignment(mp);
+
+	/*
+	 * Check that the data (and log if separate) are an ok size.
+	 */
+	error = xfs_check_sizes(mp);
+	if (error)
+		goto out_remove_uuid;
+
+	/*
+	 * Initialize realtime fields in the mount structure
+	 */
+	error = xfs_rtmount_init(mp);
+	if (error) {
+		xfs_warn(mp, "RT mount failed");
+		goto out_remove_uuid;
+	}
+
+	/*
+	 *  Copies the low order bits of the timestamp and the randomly
+	 *  set "sequence" number out of a UUID.
+	 */
+	uuid_getnodeuniq(&sbp->sb_uuid, mp->m_fixedfsid);
+
+	mp->m_dmevmask = 0;	/* not persistent; set after each mount */
+
+	xfs_dir_mount(mp);
+
+	/*
+	 * Initialize the attribute manager's entries.
+	 */
+	mp->m_attr_magicpct = (mp->m_sb.sb_blocksize * 37) / 100;
+
+	/*
+	 * Initialize the precomputed transaction reservations values.
+	 */
+	xfs_trans_init(mp);
+
+	/*
+	 * Allocate and initialize the per-ag data.
+	 */
+	spin_lock_init(&mp->m_perag_lock);
+	INIT_RADIX_TREE(&mp->m_perag_tree, GFP_ATOMIC);
+	error = xfs_initialize_perag(mp, sbp->sb_agcount, &mp->m_maxagi);
+	if (error) {
+		xfs_warn(mp, "Failed per-ag init: %d", error);
+		goto out_remove_uuid;
+	}
+
+	if (!sbp->sb_logblocks) {
+		xfs_warn(mp, "no log defined");
+		XFS_ERROR_REPORT("xfs_mountfs", XFS_ERRLEVEL_LOW, mp);
+		error = XFS_ERROR(EFSCORRUPTED);
+		goto out_free_perag;
+	}
+
+	/*
+	 * log's mount-time initialization. Perform 1st part recovery if needed
+	 */
+	error = xfs_log_mount(mp, mp->m_logdev_targp,
+			      XFS_FSB_TO_DADDR(mp, sbp->sb_logstart),
+			      XFS_FSB_TO_BB(mp, sbp->sb_logblocks));
+	if (error) {
+		xfs_warn(mp, "log mount failed");
+		goto out_free_perag;
+	}
+
+	/*
+	 * Now the log is mounted, we know if it was an unclean shutdown or
+	 * not. If it was, with the first phase of recovery has completed, we
+	 * have consistent AG blocks on disk. We have not recovered EFIs yet,
+	 * but they are recovered transactionally in the second recovery phase
+	 * later.
+	 *
+	 * Hence we can safely re-initialise incore superblock counters from
+	 * the per-ag data. These may not be correct if the filesystem was not
+	 * cleanly unmounted, so we need to wait for recovery to finish before
+	 * doing this.
+	 *
+	 * If the filesystem was cleanly unmounted, then we can trust the
+	 * values in the superblock to be correct and we don't need to do
+	 * anything here.
+	 *
+	 * If we are currently making the filesystem, the initialisation will
+	 * fail as the perag data is in an undefined state.
+	 */
+	if (xfs_sb_version_haslazysbcount(&mp->m_sb) &&
+	    !XFS_LAST_UNMOUNT_WAS_CLEAN(mp) &&
+	     !mp->m_sb.sb_inprogress) {
+		error = xfs_initialize_perag_data(mp, sbp->sb_agcount);
+		if (error)
+			goto out_free_perag;
+	}
+
+	/*
+	 * Get and sanity-check the root inode.
+	 * Save the pointer to it in the mount structure.
+	 */
+	error = xfs_iget(mp, NULL, sbp->sb_rootino, 0, XFS_ILOCK_EXCL, &rip);
+	if (error) {
+		xfs_warn(mp, "failed to read root inode");
+		goto out_log_dealloc;
+	}
+
+	ASSERT(rip != NULL);
+
+	if (unlikely(!S_ISDIR(rip->i_d.di_mode))) {
+		xfs_warn(mp, "corrupted root inode %llu: not a directory",
+			(unsigned long long)rip->i_ino);
+		xfs_iunlock(rip, XFS_ILOCK_EXCL);
+		XFS_ERROR_REPORT("xfs_mountfs_int(2)", XFS_ERRLEVEL_LOW,
+				 mp);
+		error = XFS_ERROR(EFSCORRUPTED);
+		goto out_rele_rip;
+	}
+	mp->m_rootip = rip;	/* save it */
+
+	xfs_iunlock(rip, XFS_ILOCK_EXCL);
+
+	/*
+	 * Initialize realtime inode pointers in the mount structure
+	 */
+	error = xfs_rtmount_inodes(mp);
+	if (error) {
+		/*
+		 * Free up the root inode.
+		 */
+		xfs_warn(mp, "failed to read RT inodes");
+		goto out_rele_rip;
+	}
+
+	/*
+	 * If this is a read-only mount defer the superblock updates until
+	 * the next remount into writeable mode.  Otherwise we would never
+	 * perform the update e.g. for the root filesystem.
+	 */
+	if (mp->m_update_flags && !(mp->m_flags & XFS_MOUNT_RDONLY)) {
+		error = xfs_mount_log_sb(mp, mp->m_update_flags);
+		if (error) {
+			xfs_warn(mp, "failed to write sb changes");
+			goto out_rtunmount;
+		}
+	}
+
+	/*
+	 * Initialise the XFS quota management subsystem for this mount
+	 */
+	if (XFS_IS_QUOTA_RUNNING(mp)) {
+		error = xfs_qm_newmount(mp, &quotamount, &quotaflags);
+		if (error)
+			goto out_rtunmount;
+	} else {
+		ASSERT(!XFS_IS_QUOTA_ON(mp));
+
+		/*
+		 * If a file system had quotas running earlier, but decided to
+		 * mount without -o uquota/pquota/gquota options, revoke the
+		 * quotachecked license.
+		 */
+		if (mp->m_sb.sb_qflags & XFS_ALL_QUOTA_ACCT) {
+			xfs_notice(mp, "resetting quota flags");
+			error = xfs_mount_reset_sbqflags(mp);
+			if (error)
+				return error;
+		}
+	}
+
+	/*
+	 * Finish recovering the file system.  This part needed to be
+	 * delayed until after the root and real-time bitmap inodes
+	 * were consistently read in.
+	 */
+	error = xfs_log_mount_finish(mp);
+	if (error) {
+		xfs_warn(mp, "log mount finish failed");
+		goto out_rtunmount;
+	}
+
+	/*
+	 * Complete the quota initialisation, post-log-replay component.
+	 */
+	if (quotamount) {
+		ASSERT(mp->m_qflags == 0);
+		mp->m_qflags = quotaflags;
+
+		xfs_qm_mount_quotas(mp);
+	}
+
+	/*
+	 * Now we are mounted, reserve a small amount of unused space for
+	 * privileged transactions. This is needed so that transaction
+	 * space required for critical operations can dip into this pool
+	 * when at ENOSPC. This is needed for operations like create with
+	 * attr, unwritten extent conversion at ENOSPC, etc. Data allocations
+	 * are not allowed to use this reserved space.
+	 *
+	 * This may drive us straight to ENOSPC on mount, but that implies
+	 * we were already there on the last unmount. Warn if this occurs.
+	 */
+	if (!(mp->m_flags & XFS_MOUNT_RDONLY)) {
+		resblks = xfs_default_resblks(mp);
+		error = xfs_reserve_blocks(mp, &resblks, NULL);
+		if (error)
+			xfs_warn(mp,
+	"Unable to allocate reserve blocks. Continuing without reserve pool.");
+	}
+
+	return 0;
+
+ out_rtunmount:
+	xfs_rtunmount_inodes(mp);
+ out_rele_rip:
+	IRELE(rip);
+ out_log_dealloc:
+	xfs_log_unmount(mp);
+ out_free_perag:
+	xfs_free_perag(mp);
+ out_remove_uuid:
+	xfs_uuid_unmount(mp);
+ out:
+	return error;
+}
+
+/*
+ * This flushes out the inodes,dquots and the superblock, unmounts the
+ * log and makes sure that incore structures are freed.
+ */
+void
+xfs_unmountfs(
+	struct xfs_mount	*mp)
+{
+	__uint64_t		resblks;
+	int			error;
+
+	xfs_qm_unmount_quotas(mp);
+	xfs_rtunmount_inodes(mp);
+	IRELE(mp->m_rootip);
+
+	/*
+	 * We can potentially deadlock here if we have an inode cluster
+	 * that has been freed has its buffer still pinned in memory because
+	 * the transaction is still sitting in a iclog. The stale inodes
+	 * on that buffer will have their flush locks held until the
+	 * transaction hits the disk and the callbacks run. the inode
+	 * flush takes the flush lock unconditionally and with nothing to
+	 * push out the iclog we will never get that unlocked. hence we
+	 * need to force the log first.
+	 */
+	xfs_log_force(mp, XFS_LOG_SYNC);
+
+	/*
+	 * Do a delwri reclaim pass first so that as many dirty inodes are
+	 * queued up for IO as possible. Then flush the buffers before making
+	 * a synchronous path to catch all the remaining inodes are reclaimed.
+	 * This makes the reclaim process as quick as possible by avoiding
+	 * synchronous writeout and blocking on inodes already in the delwri
+	 * state as much as possible.
+	 */
+	xfs_reclaim_inodes(mp, 0);
+	xfs_flush_buftarg(mp->m_ddev_targp, 1);
+	xfs_reclaim_inodes(mp, SYNC_WAIT);
+
+	xfs_qm_unmount(mp);
+
+	/*
+	 * Flush out the log synchronously so that we know for sure
+	 * that nothing is pinned.  This is important because bflush()
+	 * will skip pinned buffers.
+	 */
+	xfs_log_force(mp, XFS_LOG_SYNC);
+
+	/*
+	 * Unreserve any blocks we have so that when we unmount we don't account
+	 * the reserved free space as used. This is really only necessary for
+	 * lazy superblock counting because it trusts the incore superblock
+	 * counters to be absolutely correct on clean unmount.
+	 *
+	 * We don't bother correcting this elsewhere for lazy superblock
+	 * counting because on mount of an unclean filesystem we reconstruct the
+	 * correct counter value and this is irrelevant.
+	 *
+	 * For non-lazy counter filesystems, this doesn't matter at all because
+	 * we only every apply deltas to the superblock and hence the incore
+	 * value does not matter....
+	 */
+	resblks = 0;
+	error = xfs_reserve_blocks(mp, &resblks, NULL);
+	if (error)
+		xfs_warn(mp, "Unable to free reserved block pool. "
+				"Freespace may not be correct on next mount.");
+
+	error = xfs_log_sbcount(mp);
+	if (error)
+		xfs_warn(mp, "Unable to update superblock counters. "
+				"Freespace may not be correct on next mount.");
+	xfs_unmountfs_writesb(mp);
+
+	/*
+	 * Make sure all buffers have been flushed and completed before
+	 * unmounting the log.
+	 */
+	error = xfs_flush_buftarg(mp->m_ddev_targp, 1);
+	if (error)
+		xfs_warn(mp, "%d busy buffers during unmount.", error);
+	xfs_wait_buftarg(mp->m_ddev_targp);
+
+	xfs_log_unmount_write(mp);
+	xfs_log_unmount(mp);
+	xfs_uuid_unmount(mp);
+
+#if defined(DEBUG)
+	xfs_errortag_clearall(mp, 0);
+#endif
+	xfs_free_perag(mp);
+}
+
+int
+xfs_fs_writable(xfs_mount_t *mp)
+{
+	return !(xfs_test_for_freeze(mp) || XFS_FORCED_SHUTDOWN(mp) ||
+		(mp->m_flags & XFS_MOUNT_RDONLY));
+}
+
+/*
+ * xfs_log_sbcount
+ *
+ * Sync the superblock counters to disk.
+ *
+ * Note this code can be called during the process of freezing, so
+ * we may need to use the transaction allocator which does not
+ * block when the transaction subsystem is in its frozen state.
+ */
+int
+xfs_log_sbcount(xfs_mount_t *mp)
+{
+	xfs_trans_t	*tp;
+	int		error;
+
+	if (!xfs_fs_writable(mp))
+		return 0;
+
+	xfs_icsb_sync_counters(mp, 0);
+
+	/*
+	 * we don't need to do this if we are updating the superblock
+	 * counters on every modification.
+	 */
+	if (!xfs_sb_version_haslazysbcount(&mp->m_sb))
+		return 0;
+
+	tp = _xfs_trans_alloc(mp, XFS_TRANS_SB_COUNT, KM_SLEEP);
+	error = xfs_trans_reserve(tp, 0, mp->m_sb.sb_sectsize + 128, 0, 0,
+					XFS_DEFAULT_LOG_COUNT);
+	if (error) {
+		xfs_trans_cancel(tp, 0);
+		return error;
+	}
+
+	xfs_mod_sb(tp, XFS_SB_IFREE | XFS_SB_ICOUNT | XFS_SB_FDBLOCKS);
+	xfs_trans_set_sync(tp);
+	error = xfs_trans_commit(tp, 0);
+	return error;
+}
+
+int
+xfs_unmountfs_writesb(xfs_mount_t *mp)
+{
+	xfs_buf_t	*sbp;
+	int		error = 0;
+
+	/*
+	 * skip superblock write if fs is read-only, or
+	 * if we are doing a forced umount.
+	 */
+	if (!((mp->m_flags & XFS_MOUNT_RDONLY) ||
+		XFS_FORCED_SHUTDOWN(mp))) {
+
+		sbp = xfs_getsb(mp, 0);
+
+		XFS_BUF_UNDONE(sbp);
+		XFS_BUF_UNREAD(sbp);
+		xfs_buf_delwri_dequeue(sbp);
+		XFS_BUF_WRITE(sbp);
+		XFS_BUF_UNASYNC(sbp);
+		ASSERT(sbp->b_target == mp->m_ddev_targp);
+		xfsbdstrat(mp, sbp);
+		error = xfs_buf_iowait(sbp);
+		if (error)
+			xfs_buf_ioerror_alert(sbp, __func__);
+		xfs_buf_relse(sbp);
+	}
+	return error;
+}
+
+/*
+ * xfs_mod_sb() can be used to copy arbitrary changes to the
+ * in-core superblock into the superblock buffer to be logged.
+ * It does not provide the higher level of locking that is
+ * needed to protect the in-core superblock from concurrent
+ * access.
+ */
+void
+xfs_mod_sb(xfs_trans_t *tp, __int64_t fields)
+{
+	xfs_buf_t	*bp;
+	int		first;
+	int		last;
+	xfs_mount_t	*mp;
+	xfs_sb_field_t	f;
+
+	ASSERT(fields);
+	if (!fields)
+		return;
+	mp = tp->t_mountp;
+	bp = xfs_trans_getsb(tp, mp, 0);
+	first = sizeof(xfs_sb_t);
+	last = 0;
+
+	/* translate/copy */
+
+	xfs_sb_to_disk(XFS_BUF_TO_SBP(bp), &mp->m_sb, fields);
+
+	/* find modified range */
+	f = (xfs_sb_field_t)xfs_highbit64((__uint64_t)fields);
+	ASSERT((1LL << f) & XFS_SB_MOD_BITS);
+	last = xfs_sb_info[f + 1].offset - 1;
+
+	f = (xfs_sb_field_t)xfs_lowbit64((__uint64_t)fields);
+	ASSERT((1LL << f) & XFS_SB_MOD_BITS);
+	first = xfs_sb_info[f].offset;
+
+	xfs_trans_log_buf(tp, bp, first, last);
+}
+
+
+/*
+ * xfs_mod_incore_sb_unlocked() is a utility routine common used to apply
+ * a delta to a specified field in the in-core superblock.  Simply
+ * switch on the field indicated and apply the delta to that field.
+ * Fields are not allowed to dip below zero, so if the delta would
+ * do this do not apply it and return EINVAL.
+ *
+ * The m_sb_lock must be held when this routine is called.
+ */
+STATIC int
+xfs_mod_incore_sb_unlocked(
+	xfs_mount_t	*mp,
+	xfs_sb_field_t	field,
+	int64_t		delta,
+	int		rsvd)
+{
+	int		scounter;	/* short counter for 32 bit fields */
+	long long	lcounter;	/* long counter for 64 bit fields */
+	long long	res_used, rem;
+
+	/*
+	 * With the in-core superblock spin lock held, switch
+	 * on the indicated field.  Apply the delta to the
+	 * proper field.  If the fields value would dip below
+	 * 0, then do not apply the delta and return EINVAL.
+	 */
+	switch (field) {
+	case XFS_SBS_ICOUNT:
+		lcounter = (long long)mp->m_sb.sb_icount;
+		lcounter += delta;
+		if (lcounter < 0) {
+			ASSERT(0);
+			return XFS_ERROR(EINVAL);
+		}
+		mp->m_sb.sb_icount = lcounter;
+		return 0;
+	case XFS_SBS_IFREE:
+		lcounter = (long long)mp->m_sb.sb_ifree;
+		lcounter += delta;
+		if (lcounter < 0) {
+			ASSERT(0);
+			return XFS_ERROR(EINVAL);
+		}
+		mp->m_sb.sb_ifree = lcounter;
+		return 0;
+	case XFS_SBS_FDBLOCKS:
+		lcounter = (long long)
+			mp->m_sb.sb_fdblocks - XFS_ALLOC_SET_ASIDE(mp);
+		res_used = (long long)(mp->m_resblks - mp->m_resblks_avail);
+
+		if (delta > 0) {		/* Putting blocks back */
+			if (res_used > delta) {
+				mp->m_resblks_avail += delta;
+			} else {
+				rem = delta - res_used;
+				mp->m_resblks_avail = mp->m_resblks;
+				lcounter += rem;
+			}
+		} else {				/* Taking blocks away */
+			lcounter += delta;
+			if (lcounter >= 0) {
+				mp->m_sb.sb_fdblocks = lcounter +
+							XFS_ALLOC_SET_ASIDE(mp);
+				return 0;
+			}
+
+			/*
+			 * We are out of blocks, use any available reserved
+			 * blocks if were allowed to.
+			 */
+			if (!rsvd)
+				return XFS_ERROR(ENOSPC);
+
+			lcounter = (long long)mp->m_resblks_avail + delta;
+			if (lcounter >= 0) {
+				mp->m_resblks_avail = lcounter;
+				return 0;
+			}
+			printk_once(KERN_WARNING
+				"Filesystem \"%s\": reserve blocks depleted! "
+				"Consider increasing reserve pool size.",
+				mp->m_fsname);
+			return XFS_ERROR(ENOSPC);
+		}
+
+		mp->m_sb.sb_fdblocks = lcounter + XFS_ALLOC_SET_ASIDE(mp);
+		return 0;
+	case XFS_SBS_FREXTENTS:
+		lcounter = (long long)mp->m_sb.sb_frextents;
+		lcounter += delta;
+		if (lcounter < 0) {
+			return XFS_ERROR(ENOSPC);
+		}
+		mp->m_sb.sb_frextents = lcounter;
+		return 0;
+	case XFS_SBS_DBLOCKS:
+		lcounter = (long long)mp->m_sb.sb_dblocks;
+		lcounter += delta;
+		if (lcounter < 0) {
+			ASSERT(0);
+			return XFS_ERROR(EINVAL);
+		}
+		mp->m_sb.sb_dblocks = lcounter;
+		return 0;
+	case XFS_SBS_AGCOUNT:
+		scounter = mp->m_sb.sb_agcount;
+		scounter += delta;
+		if (scounter < 0) {
+			ASSERT(0);
+			return XFS_ERROR(EINVAL);
+		}
+		mp->m_sb.sb_agcount = scounter;
+		return 0;
+	case XFS_SBS_IMAX_PCT:
+		scounter = mp->m_sb.sb_imax_pct;
+		scounter += delta;
+		if (scounter < 0) {
+			ASSERT(0);
+			return XFS_ERROR(EINVAL);
+		}
+		mp->m_sb.sb_imax_pct = scounter;
+		return 0;
+	case XFS_SBS_REXTSIZE:
+		scounter = mp->m_sb.sb_rextsize;
+		scounter += delta;
+		if (scounter < 0) {
+			ASSERT(0);
+			return XFS_ERROR(EINVAL);
+		}
+		mp->m_sb.sb_rextsize = scounter;
+		return 0;
+	case XFS_SBS_RBMBLOCKS:
+		scounter = mp->m_sb.sb_rbmblocks;
+		scounter += delta;
+		if (scounter < 0) {
+			ASSERT(0);
+			return XFS_ERROR(EINVAL);
+		}
+		mp->m_sb.sb_rbmblocks = scounter;
+		return 0;
+	case XFS_SBS_RBLOCKS:
+		lcounter = (long long)mp->m_sb.sb_rblocks;
+		lcounter += delta;
+		if (lcounter < 0) {
+			ASSERT(0);
+			return XFS_ERROR(EINVAL);
+		}
+		mp->m_sb.sb_rblocks = lcounter;
+		return 0;
+	case XFS_SBS_REXTENTS:
+		lcounter = (long long)mp->m_sb.sb_rextents;
+		lcounter += delta;
+		if (lcounter < 0) {
+			ASSERT(0);
+			return XFS_ERROR(EINVAL);
+		}
+		mp->m_sb.sb_rextents = lcounter;
+		return 0;
+	case XFS_SBS_REXTSLOG:
+		scounter = mp->m_sb.sb_rextslog;
+		scounter += delta;
+		if (scounter < 0) {
+			ASSERT(0);
+			return XFS_ERROR(EINVAL);
+		}
+		mp->m_sb.sb_rextslog = scounter;
+		return 0;
+	default:
+		ASSERT(0);
+		return XFS_ERROR(EINVAL);
+	}
+}
+
+/*
+ * xfs_mod_incore_sb() is used to change a field in the in-core
+ * superblock structure by the specified delta.  This modification
+ * is protected by the m_sb_lock.  Just use the xfs_mod_incore_sb_unlocked()
+ * routine to do the work.
+ */
+int
+xfs_mod_incore_sb(
+	struct xfs_mount	*mp,
+	xfs_sb_field_t		field,
+	int64_t			delta,
+	int			rsvd)
+{
+	int			status;
+
+#ifdef HAVE_PERCPU_SB
+	ASSERT(field < XFS_SBS_ICOUNT || field > XFS_SBS_FDBLOCKS);
+#endif
+	spin_lock(&mp->m_sb_lock);
+	status = xfs_mod_incore_sb_unlocked(mp, field, delta, rsvd);
+	spin_unlock(&mp->m_sb_lock);
+
+	return status;
+}
+
+/*
+ * Change more than one field in the in-core superblock structure at a time.
+ *
+ * The fields and changes to those fields are specified in the array of
+ * xfs_mod_sb structures passed in.  Either all of the specified deltas
+ * will be applied or none of them will.  If any modified field dips below 0,
+ * then all modifications will be backed out and EINVAL will be returned.
+ *
+ * Note that this function may not be used for the superblock values that
+ * are tracked with the in-memory per-cpu counters - a direct call to
+ * xfs_icsb_modify_counters is required for these.
+ */
+int
+xfs_mod_incore_sb_batch(
+	struct xfs_mount	*mp,
+	xfs_mod_sb_t		*msb,
+	uint			nmsb,
+	int			rsvd)
+{
+	xfs_mod_sb_t		*msbp;
+	int			error = 0;
+
+	/*
+	 * Loop through the array of mod structures and apply each individually.
+	 * If any fail, then back out all those which have already been applied.
+	 * Do all of this within the scope of the m_sb_lock so that all of the
+	 * changes will be atomic.
+	 */
+	spin_lock(&mp->m_sb_lock);
+	for (msbp = msb; msbp < (msb + nmsb); msbp++) {
+		ASSERT(msbp->msb_field < XFS_SBS_ICOUNT ||
+		       msbp->msb_field > XFS_SBS_FDBLOCKS);
+
+		error = xfs_mod_incore_sb_unlocked(mp, msbp->msb_field,
+						   msbp->msb_delta, rsvd);
+		if (error)
+			goto unwind;
+	}
+	spin_unlock(&mp->m_sb_lock);
+	return 0;
+
+unwind:
+	while (--msbp >= msb) {
+		error = xfs_mod_incore_sb_unlocked(mp, msbp->msb_field,
+						   -msbp->msb_delta, rsvd);
+		ASSERT(error == 0);
+	}
+	spin_unlock(&mp->m_sb_lock);
+	return error;
+}
+
+/*
+ * xfs_getsb() is called to obtain the buffer for the superblock.
+ * The buffer is returned locked and read in from disk.
+ * The buffer should be released with a call to xfs_brelse().
+ *
+ * If the flags parameter is BUF_TRYLOCK, then we'll only return
+ * the superblock buffer if it can be locked without sleeping.
+ * If it can't then we'll return NULL.
+ */
+struct xfs_buf *
+xfs_getsb(
+	struct xfs_mount	*mp,
+	int			flags)
+{
+	struct xfs_buf		*bp = mp->m_sb_bp;
+
+	if (!xfs_buf_trylock(bp)) {
+		if (flags & XBF_TRYLOCK)
+			return NULL;
+		xfs_buf_lock(bp);
+	}
+
+	xfs_buf_hold(bp);
+	ASSERT(XFS_BUF_ISDONE(bp));
+	return bp;
+}
+
+/*
+ * Used to free the superblock along various error paths.
+ */
+void
+xfs_freesb(
+	struct xfs_mount	*mp)
+{
+	struct xfs_buf		*bp = mp->m_sb_bp;
+
+	xfs_buf_lock(bp);
+	mp->m_sb_bp = NULL;
+	xfs_buf_relse(bp);
+}
+
+/*
+ * Used to log changes to the superblock unit and width fields which could
+ * be altered by the mount options, as well as any potential sb_features2
+ * fixup. Only the first superblock is updated.
+ */
+int
+xfs_mount_log_sb(
+	xfs_mount_t	*mp,
+	__int64_t	fields)
+{
+	xfs_trans_t	*tp;
+	int		error;
+
+	ASSERT(fields & (XFS_SB_UNIT | XFS_SB_WIDTH | XFS_SB_UUID |
+			 XFS_SB_FEATURES2 | XFS_SB_BAD_FEATURES2 |
+			 XFS_SB_VERSIONNUM));
+
+	tp = xfs_trans_alloc(mp, XFS_TRANS_SB_UNIT);
+	error = xfs_trans_reserve(tp, 0, mp->m_sb.sb_sectsize + 128, 0, 0,
+				XFS_DEFAULT_LOG_COUNT);
+	if (error) {
+		xfs_trans_cancel(tp, 0);
+		return error;
+	}
+	xfs_mod_sb(tp, fields);
+	error = xfs_trans_commit(tp, 0);
+	return error;
+}
+
+/*
+ * If the underlying (data/log/rt) device is readonly, there are some
+ * operations that cannot proceed.
+ */
+int
+xfs_dev_is_read_only(
+	struct xfs_mount	*mp,
+	char			*message)
+{
+	if (xfs_readonly_buftarg(mp->m_ddev_targp) ||
+	    xfs_readonly_buftarg(mp->m_logdev_targp) ||
+	    (mp->m_rtdev_targp && xfs_readonly_buftarg(mp->m_rtdev_targp))) {
+		xfs_notice(mp, "%s required on read-only device.", message);
+		xfs_notice(mp, "write access unavailable, cannot proceed.");
+		return EROFS;
+	}
+	return 0;
+}
+
+#ifdef HAVE_PERCPU_SB
+/*
+ * Per-cpu incore superblock counters
+ *
+ * Simple concept, difficult implementation
+ *
+ * Basically, replace the incore superblock counters with a distributed per cpu
+ * counter for contended fields (e.g.  free block count).
+ *
+ * Difficulties arise in that the incore sb is used for ENOSPC checking, and
+ * hence needs to be accurately read when we are running low on space. Hence
+ * there is a method to enable and disable the per-cpu counters based on how
+ * much "stuff" is available in them.
+ *
+ * Basically, a counter is enabled if there is enough free resource to justify
+ * running a per-cpu fast-path. If the per-cpu counter runs out (i.e. a local
+ * ENOSPC), then we disable the counters to synchronise all callers and
+ * re-distribute the available resources.
+ *
+ * If, once we redistributed the available resources, we still get a failure,
+ * we disable the per-cpu counter and go through the slow path.
+ *
+ * The slow path is the current xfs_mod_incore_sb() function.  This means that
+ * when we disable a per-cpu counter, we need to drain its resources back to
+ * the global superblock. We do this after disabling the counter to prevent
+ * more threads from queueing up on the counter.
+ *
+ * Essentially, this means that we still need a lock in the fast path to enable
+ * synchronisation between the global counters and the per-cpu counters. This
+ * is not a problem because the lock will be local to a CPU almost all the time
+ * and have little contention except when we get to ENOSPC conditions.
+ *
+ * Basically, this lock becomes a barrier that enables us to lock out the fast
+ * path while we do things like enabling and disabling counters and
+ * synchronising the counters.
+ *
+ * Locking rules:
+ *
+ * 	1. m_sb_lock before picking up per-cpu locks
+ * 	2. per-cpu locks always picked up via for_each_online_cpu() order
+ * 	3. accurate counter sync requires m_sb_lock + per cpu locks
+ * 	4. modifying per-cpu counters requires holding per-cpu lock
+ * 	5. modifying global counters requires holding m_sb_lock
+ *	6. enabling or disabling a counter requires holding the m_sb_lock 
+ *	   and _none_ of the per-cpu locks.
+ *
+ * Disabled counters are only ever re-enabled by a balance operation
+ * that results in more free resources per CPU than a given threshold.
+ * To ensure counters don't remain disabled, they are rebalanced when
+ * the global resource goes above a higher threshold (i.e. some hysteresis
+ * is present to prevent thrashing).
+ */
+
+#ifdef CONFIG_HOTPLUG_CPU
+/*
+ * hot-plug CPU notifier support.
+ *
+ * We need a notifier per filesystem as we need to be able to identify
+ * the filesystem to balance the counters out. This is achieved by
+ * having a notifier block embedded in the xfs_mount_t and doing pointer
+ * magic to get the mount pointer from the notifier block address.
+ */
+STATIC int
+xfs_icsb_cpu_notify(
+	struct notifier_block *nfb,
+	unsigned long action,
+	void *hcpu)
+{
+	xfs_icsb_cnts_t *cntp;
+	xfs_mount_t	*mp;
+
+	mp = (xfs_mount_t *)container_of(nfb, xfs_mount_t, m_icsb_notifier);
+	cntp = (xfs_icsb_cnts_t *)
+			per_cpu_ptr(mp->m_sb_cnts, (unsigned long)hcpu);
+	switch (action) {
+	case CPU_UP_PREPARE:
+	case CPU_UP_PREPARE_FROZEN:
+		/* Easy Case - initialize the area and locks, and
+		 * then rebalance when online does everything else for us. */
+		memset(cntp, 0, sizeof(xfs_icsb_cnts_t));
+		break;
+	case CPU_ONLINE:
+	case CPU_ONLINE_FROZEN:
+		xfs_icsb_lock(mp);
+		xfs_icsb_balance_counter(mp, XFS_SBS_ICOUNT, 0);
+		xfs_icsb_balance_counter(mp, XFS_SBS_IFREE, 0);
+		xfs_icsb_balance_counter(mp, XFS_SBS_FDBLOCKS, 0);
+		xfs_icsb_unlock(mp);
+		break;
+	case CPU_DEAD:
+	case CPU_DEAD_FROZEN:
+		/* Disable all the counters, then fold the dead cpu's
+		 * count into the total on the global superblock and
+		 * re-enable the counters. */
+		xfs_icsb_lock(mp);
+		spin_lock(&mp->m_sb_lock);
+		xfs_icsb_disable_counter(mp, XFS_SBS_ICOUNT);
+		xfs_icsb_disable_counter(mp, XFS_SBS_IFREE);
+		xfs_icsb_disable_counter(mp, XFS_SBS_FDBLOCKS);
+
+		mp->m_sb.sb_icount += cntp->icsb_icount;
+		mp->m_sb.sb_ifree += cntp->icsb_ifree;
+		mp->m_sb.sb_fdblocks += cntp->icsb_fdblocks;
+
+		memset(cntp, 0, sizeof(xfs_icsb_cnts_t));
+
+		xfs_icsb_balance_counter_locked(mp, XFS_SBS_ICOUNT, 0);
+		xfs_icsb_balance_counter_locked(mp, XFS_SBS_IFREE, 0);
+		xfs_icsb_balance_counter_locked(mp, XFS_SBS_FDBLOCKS, 0);
+		spin_unlock(&mp->m_sb_lock);
+		xfs_icsb_unlock(mp);
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+#endif /* CONFIG_HOTPLUG_CPU */
+
+int
+xfs_icsb_init_counters(
+	xfs_mount_t	*mp)
+{
+	xfs_icsb_cnts_t *cntp;
+	int		i;
+
+	mp->m_sb_cnts = alloc_percpu(xfs_icsb_cnts_t);
+	if (mp->m_sb_cnts == NULL)
+		return -ENOMEM;
+
+#ifdef CONFIG_HOTPLUG_CPU
+	mp->m_icsb_notifier.notifier_call = xfs_icsb_cpu_notify;
+	mp->m_icsb_notifier.priority = 0;
+	register_hotcpu_notifier(&mp->m_icsb_notifier);
+#endif /* CONFIG_HOTPLUG_CPU */
+
+	for_each_online_cpu(i) {
+		cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
+		memset(cntp, 0, sizeof(xfs_icsb_cnts_t));
+	}
+
+	mutex_init(&mp->m_icsb_mutex);
+
+	/*
+	 * start with all counters disabled so that the
+	 * initial balance kicks us off correctly
+	 */
+	mp->m_icsb_counters = -1;
+	return 0;
+}
+
+void
+xfs_icsb_reinit_counters(
+	xfs_mount_t	*mp)
+{
+	xfs_icsb_lock(mp);
+	/*
+	 * start with all counters disabled so that the
+	 * initial balance kicks us off correctly
+	 */
+	mp->m_icsb_counters = -1;
+	xfs_icsb_balance_counter(mp, XFS_SBS_ICOUNT, 0);
+	xfs_icsb_balance_counter(mp, XFS_SBS_IFREE, 0);
+	xfs_icsb_balance_counter(mp, XFS_SBS_FDBLOCKS, 0);
+	xfs_icsb_unlock(mp);
+}
+
+void
+xfs_icsb_destroy_counters(
+	xfs_mount_t	*mp)
+{
+	if (mp->m_sb_cnts) {
+		unregister_hotcpu_notifier(&mp->m_icsb_notifier);
+		free_percpu(mp->m_sb_cnts);
+	}
+	mutex_destroy(&mp->m_icsb_mutex);
+}
+
+STATIC void
+xfs_icsb_lock_cntr(
+	xfs_icsb_cnts_t	*icsbp)
+{
+	while (test_and_set_bit(XFS_ICSB_FLAG_LOCK, &icsbp->icsb_flags)) {
+		ndelay(1000);
+	}
+}
+
+STATIC void
+xfs_icsb_unlock_cntr(
+	xfs_icsb_cnts_t	*icsbp)
+{
+	clear_bit(XFS_ICSB_FLAG_LOCK, &icsbp->icsb_flags);
+}
+
+
+STATIC void
+xfs_icsb_lock_all_counters(
+	xfs_mount_t	*mp)
+{
+	xfs_icsb_cnts_t *cntp;
+	int		i;
+
+	for_each_online_cpu(i) {
+		cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
+		xfs_icsb_lock_cntr(cntp);
+	}
+}
+
+STATIC void
+xfs_icsb_unlock_all_counters(
+	xfs_mount_t	*mp)
+{
+	xfs_icsb_cnts_t *cntp;
+	int		i;
+
+	for_each_online_cpu(i) {
+		cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
+		xfs_icsb_unlock_cntr(cntp);
+	}
+}
+
+STATIC void
+xfs_icsb_count(
+	xfs_mount_t	*mp,
+	xfs_icsb_cnts_t	*cnt,
+	int		flags)
+{
+	xfs_icsb_cnts_t *cntp;
+	int		i;
+
+	memset(cnt, 0, sizeof(xfs_icsb_cnts_t));
+
+	if (!(flags & XFS_ICSB_LAZY_COUNT))
+		xfs_icsb_lock_all_counters(mp);
+
+	for_each_online_cpu(i) {
+		cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
+		cnt->icsb_icount += cntp->icsb_icount;
+		cnt->icsb_ifree += cntp->icsb_ifree;
+		cnt->icsb_fdblocks += cntp->icsb_fdblocks;
+	}
+
+	if (!(flags & XFS_ICSB_LAZY_COUNT))
+		xfs_icsb_unlock_all_counters(mp);
+}
+
+STATIC int
+xfs_icsb_counter_disabled(
+	xfs_mount_t	*mp,
+	xfs_sb_field_t	field)
+{
+	ASSERT((field >= XFS_SBS_ICOUNT) && (field <= XFS_SBS_FDBLOCKS));
+	return test_bit(field, &mp->m_icsb_counters);
+}
+
+STATIC void
+xfs_icsb_disable_counter(
+	xfs_mount_t	*mp,
+	xfs_sb_field_t	field)
+{
+	xfs_icsb_cnts_t	cnt;
+
+	ASSERT((field >= XFS_SBS_ICOUNT) && (field <= XFS_SBS_FDBLOCKS));
+
+	/*
+	 * If we are already disabled, then there is nothing to do
+	 * here. We check before locking all the counters to avoid
+	 * the expensive lock operation when being called in the
+	 * slow path and the counter is already disabled. This is
+	 * safe because the only time we set or clear this state is under
+	 * the m_icsb_mutex.
+	 */
+	if (xfs_icsb_counter_disabled(mp, field))
+		return;
+
+	xfs_icsb_lock_all_counters(mp);
+	if (!test_and_set_bit(field, &mp->m_icsb_counters)) {
+		/* drain back to superblock */
+
+		xfs_icsb_count(mp, &cnt, XFS_ICSB_LAZY_COUNT);
+		switch(field) {
+		case XFS_SBS_ICOUNT:
+			mp->m_sb.sb_icount = cnt.icsb_icount;
+			break;
+		case XFS_SBS_IFREE:
+			mp->m_sb.sb_ifree = cnt.icsb_ifree;
+			break;
+		case XFS_SBS_FDBLOCKS:
+			mp->m_sb.sb_fdblocks = cnt.icsb_fdblocks;
+			break;
+		default:
+			BUG();
+		}
+	}
+
+	xfs_icsb_unlock_all_counters(mp);
+}
+
+STATIC void
+xfs_icsb_enable_counter(
+	xfs_mount_t	*mp,
+	xfs_sb_field_t	field,
+	uint64_t	count,
+	uint64_t	resid)
+{
+	xfs_icsb_cnts_t	*cntp;
+	int		i;
+
+	ASSERT((field >= XFS_SBS_ICOUNT) && (field <= XFS_SBS_FDBLOCKS));
+
+	xfs_icsb_lock_all_counters(mp);
+	for_each_online_cpu(i) {
+		cntp = per_cpu_ptr(mp->m_sb_cnts, i);
+		switch (field) {
+		case XFS_SBS_ICOUNT:
+			cntp->icsb_icount = count + resid;
+			break;
+		case XFS_SBS_IFREE:
+			cntp->icsb_ifree = count + resid;
+			break;
+		case XFS_SBS_FDBLOCKS:
+			cntp->icsb_fdblocks = count + resid;
+			break;
+		default:
+			BUG();
+			break;
+		}
+		resid = 0;
+	}
+	clear_bit(field, &mp->m_icsb_counters);
+	xfs_icsb_unlock_all_counters(mp);
+}
+
+void
+xfs_icsb_sync_counters_locked(
+	xfs_mount_t	*mp,
+	int		flags)
+{
+	xfs_icsb_cnts_t	cnt;
+
+	xfs_icsb_count(mp, &cnt, flags);
+
+	if (!xfs_icsb_counter_disabled(mp, XFS_SBS_ICOUNT))
+		mp->m_sb.sb_icount = cnt.icsb_icount;
+	if (!xfs_icsb_counter_disabled(mp, XFS_SBS_IFREE))
+		mp->m_sb.sb_ifree = cnt.icsb_ifree;
+	if (!xfs_icsb_counter_disabled(mp, XFS_SBS_FDBLOCKS))
+		mp->m_sb.sb_fdblocks = cnt.icsb_fdblocks;
+}
+
+/*
+ * Accurate update of per-cpu counters to incore superblock
+ */
+void
+xfs_icsb_sync_counters(
+	xfs_mount_t	*mp,
+	int		flags)
+{
+	spin_lock(&mp->m_sb_lock);
+	xfs_icsb_sync_counters_locked(mp, flags);
+	spin_unlock(&mp->m_sb_lock);
+}
+
+/*
+ * Balance and enable/disable counters as necessary.
+ *
+ * Thresholds for re-enabling counters are somewhat magic.  inode counts are
+ * chosen to be the same number as single on disk allocation chunk per CPU, and
+ * free blocks is something far enough zero that we aren't going thrash when we
+ * get near ENOSPC. We also need to supply a minimum we require per cpu to
+ * prevent looping endlessly when xfs_alloc_space asks for more than will
+ * be distributed to a single CPU but each CPU has enough blocks to be
+ * reenabled.
+ *
+ * Note that we can be called when counters are already disabled.
+ * xfs_icsb_disable_counter() optimises the counter locking in this case to
+ * prevent locking every per-cpu counter needlessly.
+ */
+
+#define XFS_ICSB_INO_CNTR_REENABLE	(uint64_t)64
+#define XFS_ICSB_FDBLK_CNTR_REENABLE(mp) \
+		(uint64_t)(512 + XFS_ALLOC_SET_ASIDE(mp))
+STATIC void
+xfs_icsb_balance_counter_locked(
+	xfs_mount_t	*mp,
+	xfs_sb_field_t  field,
+	int		min_per_cpu)
+{
+	uint64_t	count, resid;
+	int		weight = num_online_cpus();
+	uint64_t	min = (uint64_t)min_per_cpu;
+
+	/* disable counter and sync counter */
+	xfs_icsb_disable_counter(mp, field);
+
+	/* update counters  - first CPU gets residual*/
+	switch (field) {
+	case XFS_SBS_ICOUNT:
+		count = mp->m_sb.sb_icount;
+		resid = do_div(count, weight);
+		if (count < max(min, XFS_ICSB_INO_CNTR_REENABLE))
+			return;
+		break;
+	case XFS_SBS_IFREE:
+		count = mp->m_sb.sb_ifree;
+		resid = do_div(count, weight);
+		if (count < max(min, XFS_ICSB_INO_CNTR_REENABLE))
+			return;
+		break;
+	case XFS_SBS_FDBLOCKS:
+		count = mp->m_sb.sb_fdblocks;
+		resid = do_div(count, weight);
+		if (count < max(min, XFS_ICSB_FDBLK_CNTR_REENABLE(mp)))
+			return;
+		break;
+	default:
+		BUG();
+		count = resid = 0;	/* quiet, gcc */
+		break;
+	}
+
+	xfs_icsb_enable_counter(mp, field, count, resid);
+}
+
+STATIC void
+xfs_icsb_balance_counter(
+	xfs_mount_t	*mp,
+	xfs_sb_field_t  fields,
+	int		min_per_cpu)
+{
+	spin_lock(&mp->m_sb_lock);
+	xfs_icsb_balance_counter_locked(mp, fields, min_per_cpu);
+	spin_unlock(&mp->m_sb_lock);
+}
+
+int
+xfs_icsb_modify_counters(
+	xfs_mount_t	*mp,
+	xfs_sb_field_t	field,
+	int64_t		delta,
+	int		rsvd)
+{
+	xfs_icsb_cnts_t	*icsbp;
+	long long	lcounter;	/* long counter for 64 bit fields */
+	int		ret = 0;
+
+	might_sleep();
+again:
+	preempt_disable();
+	icsbp = this_cpu_ptr(mp->m_sb_cnts);
+
+	/*
+	 * if the counter is disabled, go to slow path
+	 */
+	if (unlikely(xfs_icsb_counter_disabled(mp, field)))
+		goto slow_path;
+	xfs_icsb_lock_cntr(icsbp);
+	if (unlikely(xfs_icsb_counter_disabled(mp, field))) {
+		xfs_icsb_unlock_cntr(icsbp);
+		goto slow_path;
+	}
+
+	switch (field) {
+	case XFS_SBS_ICOUNT:
+		lcounter = icsbp->icsb_icount;
+		lcounter += delta;
+		if (unlikely(lcounter < 0))
+			goto balance_counter;
+		icsbp->icsb_icount = lcounter;
+		break;
+
+	case XFS_SBS_IFREE:
+		lcounter = icsbp->icsb_ifree;
+		lcounter += delta;
+		if (unlikely(lcounter < 0))
+			goto balance_counter;
+		icsbp->icsb_ifree = lcounter;
+		break;
+
+	case XFS_SBS_FDBLOCKS:
+		BUG_ON((mp->m_resblks - mp->m_resblks_avail) != 0);
+
+		lcounter = icsbp->icsb_fdblocks - XFS_ALLOC_SET_ASIDE(mp);
+		lcounter += delta;
+		if (unlikely(lcounter < 0))
+			goto balance_counter;
+		icsbp->icsb_fdblocks = lcounter + XFS_ALLOC_SET_ASIDE(mp);
+		break;
+	default:
+		BUG();
+		break;
+	}
+	xfs_icsb_unlock_cntr(icsbp);
+	preempt_enable();
+	return 0;
+
+slow_path:
+	preempt_enable();
+
+	/*
+	 * serialise with a mutex so we don't burn lots of cpu on
+	 * the superblock lock. We still need to hold the superblock
+	 * lock, however, when we modify the global structures.
+	 */
+	xfs_icsb_lock(mp);
+
+	/*
+	 * Now running atomically.
+	 *
+	 * If the counter is enabled, someone has beaten us to rebalancing.
+	 * Drop the lock and try again in the fast path....
+	 */
+	if (!(xfs_icsb_counter_disabled(mp, field))) {
+		xfs_icsb_unlock(mp);
+		goto again;
+	}
+
+	/*
+	 * The counter is currently disabled. Because we are
+	 * running atomically here, we know a rebalance cannot
+	 * be in progress. Hence we can go straight to operating
+	 * on the global superblock. We do not call xfs_mod_incore_sb()
+	 * here even though we need to get the m_sb_lock. Doing so
+	 * will cause us to re-enter this function and deadlock.
+	 * Hence we get the m_sb_lock ourselves and then call
+	 * xfs_mod_incore_sb_unlocked() as the unlocked path operates
+	 * directly on the global counters.
+	 */
+	spin_lock(&mp->m_sb_lock);
+	ret = xfs_mod_incore_sb_unlocked(mp, field, delta, rsvd);
+	spin_unlock(&mp->m_sb_lock);
+
+	/*
+	 * Now that we've modified the global superblock, we
+	 * may be able to re-enable the distributed counters
+	 * (e.g. lots of space just got freed). After that
+	 * we are done.
+	 */
+	if (ret != ENOSPC)
+		xfs_icsb_balance_counter(mp, field, 0);
+	xfs_icsb_unlock(mp);
+	return ret;
+
+balance_counter:
+	xfs_icsb_unlock_cntr(icsbp);
+	preempt_enable();
+
+	/*
+	 * We may have multiple threads here if multiple per-cpu
+	 * counters run dry at the same time. This will mean we can
+	 * do more balances than strictly necessary but it is not
+	 * the common slowpath case.
+	 */
+	xfs_icsb_lock(mp);
+
+	/*
+	 * running atomically.
+	 *
+	 * This will leave the counter in the correct state for future
+	 * accesses. After the rebalance, we simply try again and our retry
+	 * will either succeed through the fast path or slow path without
+	 * another balance operation being required.
+	 */
+	xfs_icsb_balance_counter(mp, field, delta);
+	xfs_icsb_unlock(mp);
+	goto again;
+}
+
+#endif