Add the rt linux 4.1.3-rt3 as base

Import the rt linux 4.1.3-rt3 as OPNFV kvm base.

It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and
the base is:

commit 0917f823c59692d751951bf5ea699a2d1e2f26a2
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date:   Sat Jul 25 12:13:34 2015 +0200

    Prepare v4.1.3-rt3

    Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

We lose all the git history this way and it's not good. We
should apply another opnfv project repo in future.

Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423
Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>

1 files changed, 1534 insertions, 0 deletions

diff --git a/kernel/fs/xfs/xfs_file.c b/kernel/fs/xfs/xfs_file.c
new file mode 100644
index 000000000..3b7591224
--- /dev/null
+++ b/kernel/fs/xfs/xfs_file.c
@@ -0,0 +1,1534 @@
+/*
+ * 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_shared.h"
+#include "xfs_format.h"
+#include "xfs_log_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_mount.h"
+#include "xfs_da_format.h"
+#include "xfs_da_btree.h"
+#include "xfs_inode.h"
+#include "xfs_trans.h"
+#include "xfs_inode_item.h"
+#include "xfs_bmap.h"
+#include "xfs_bmap_util.h"
+#include "xfs_error.h"
+#include "xfs_dir2.h"
+#include "xfs_dir2_priv.h"
+#include "xfs_ioctl.h"
+#include "xfs_trace.h"
+#include "xfs_log.h"
+#include "xfs_icache.h"
+#include "xfs_pnfs.h"
+
+#include <linux/dcache.h>
+#include <linux/falloc.h>
+#include <linux/pagevec.h>
+
+static const struct vm_operations_struct xfs_file_vm_ops;
+
+/*
+ * Locking primitives for read and write IO paths to ensure we consistently use
+ * and order the inode->i_mutex, ip->i_lock and ip->i_iolock.
+ */
+static inline void
+xfs_rw_ilock(
+	struct xfs_inode	*ip,
+	int			type)
+{
+	if (type & XFS_IOLOCK_EXCL)
+		mutex_lock(&VFS_I(ip)->i_mutex);
+	xfs_ilock(ip, type);
+}
+
+static inline void
+xfs_rw_iunlock(
+	struct xfs_inode	*ip,
+	int			type)
+{
+	xfs_iunlock(ip, type);
+	if (type & XFS_IOLOCK_EXCL)
+		mutex_unlock(&VFS_I(ip)->i_mutex);
+}
+
+static inline void
+xfs_rw_ilock_demote(
+	struct xfs_inode	*ip,
+	int			type)
+{
+	xfs_ilock_demote(ip, type);
+	if (type & XFS_IOLOCK_EXCL)
+		mutex_unlock(&VFS_I(ip)->i_mutex);
+}
+
+/*
+ *	xfs_iozero
+ *
+ *	xfs_iozero clears the specified range of buffer supplied,
+ *	and marks all the affected blocks as valid and modified.  If
+ *	an affected block is not allocated, it will be allocated.  If
+ *	an affected block is not completely overwritten, and is not
+ *	valid before the operation, it will be read from disk before
+ *	being partially zeroed.
+ */
+int
+xfs_iozero(
+	struct xfs_inode	*ip,	/* inode			*/
+	loff_t			pos,	/* offset in file		*/
+	size_t			count)	/* size of data to zero		*/
+{
+	struct page		*page;
+	struct address_space	*mapping;
+	int			status;
+
+	mapping = VFS_I(ip)->i_mapping;
+	do {
+		unsigned offset, bytes;
+		void *fsdata;
+
+		offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
+		bytes = PAGE_CACHE_SIZE - offset;
+		if (bytes > count)
+			bytes = count;
+
+		status = pagecache_write_begin(NULL, mapping, pos, bytes,
+					AOP_FLAG_UNINTERRUPTIBLE,
+					&page, &fsdata);
+		if (status)
+			break;
+
+		zero_user(page, offset, bytes);
+
+		status = pagecache_write_end(NULL, mapping, pos, bytes, bytes,
+					page, fsdata);
+		WARN_ON(status <= 0); /* can't return less than zero! */
+		pos += bytes;
+		count -= bytes;
+		status = 0;
+	} while (count);
+
+	return status;
+}
+
+int
+xfs_update_prealloc_flags(
+	struct xfs_inode	*ip,
+	enum xfs_prealloc_flags	flags)
+{
+	struct xfs_trans	*tp;
+	int			error;
+
+	tp = xfs_trans_alloc(ip->i_mount, XFS_TRANS_WRITEID);
+	error = xfs_trans_reserve(tp, &M_RES(ip->i_mount)->tr_writeid, 0, 0);
+	if (error) {
+		xfs_trans_cancel(tp, 0);
+		return error;
+	}
+
+	xfs_ilock(ip, XFS_ILOCK_EXCL);
+	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
+
+	if (!(flags & XFS_PREALLOC_INVISIBLE)) {
+		ip->i_d.di_mode &= ~S_ISUID;
+		if (ip->i_d.di_mode & S_IXGRP)
+			ip->i_d.di_mode &= ~S_ISGID;
+		xfs_trans_ichgtime(tp, ip, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
+	}
+
+	if (flags & XFS_PREALLOC_SET)
+		ip->i_d.di_flags |= XFS_DIFLAG_PREALLOC;
+	if (flags & XFS_PREALLOC_CLEAR)
+		ip->i_d.di_flags &= ~XFS_DIFLAG_PREALLOC;
+
+	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
+	if (flags & XFS_PREALLOC_SYNC)
+		xfs_trans_set_sync(tp);
+	return xfs_trans_commit(tp, 0);
+}
+
+/*
+ * Fsync operations on directories are much simpler than on regular files,
+ * as there is no file data to flush, and thus also no need for explicit
+ * cache flush operations, and there are no non-transaction metadata updates
+ * on directories either.
+ */
+STATIC int
+xfs_dir_fsync(
+	struct file		*file,
+	loff_t			start,
+	loff_t			end,
+	int			datasync)
+{
+	struct xfs_inode	*ip = XFS_I(file->f_mapping->host);
+	struct xfs_mount	*mp = ip->i_mount;
+	xfs_lsn_t		lsn = 0;
+
+	trace_xfs_dir_fsync(ip);
+
+	xfs_ilock(ip, XFS_ILOCK_SHARED);
+	if (xfs_ipincount(ip))
+		lsn = ip->i_itemp->ili_last_lsn;
+	xfs_iunlock(ip, XFS_ILOCK_SHARED);
+
+	if (!lsn)
+		return 0;
+	return _xfs_log_force_lsn(mp, lsn, XFS_LOG_SYNC, NULL);
+}
+
+STATIC int
+xfs_file_fsync(
+	struct file		*file,
+	loff_t			start,
+	loff_t			end,
+	int			datasync)
+{
+	struct inode		*inode = file->f_mapping->host;
+	struct xfs_inode	*ip = XFS_I(inode);
+	struct xfs_mount	*mp = ip->i_mount;
+	int			error = 0;
+	int			log_flushed = 0;
+	xfs_lsn_t		lsn = 0;
+
+	trace_xfs_file_fsync(ip);
+
+	error = filemap_write_and_wait_range(inode->i_mapping, start, end);
+	if (error)
+		return error;
+
+	if (XFS_FORCED_SHUTDOWN(mp))
+		return -EIO;
+
+	xfs_iflags_clear(ip, XFS_ITRUNCATED);
+
+	if (mp->m_flags & XFS_MOUNT_BARRIER) {
+		/*
+		 * If we have an RT and/or log subvolume we need to make sure
+		 * to flush the write cache the device used for file data
+		 * first.  This is to ensure newly written file data make
+		 * it to disk before logging the new inode size in case of
+		 * an extending write.
+		 */
+		if (XFS_IS_REALTIME_INODE(ip))
+			xfs_blkdev_issue_flush(mp->m_rtdev_targp);
+		else if (mp->m_logdev_targp != mp->m_ddev_targp)
+			xfs_blkdev_issue_flush(mp->m_ddev_targp);
+	}
+
+	/*
+	 * All metadata updates are logged, which means that we just have
+	 * to flush the log up to the latest LSN that touched the inode.
+	 */
+	xfs_ilock(ip, XFS_ILOCK_SHARED);
+	if (xfs_ipincount(ip)) {
+		if (!datasync ||
+		    (ip->i_itemp->ili_fields & ~XFS_ILOG_TIMESTAMP))
+			lsn = ip->i_itemp->ili_last_lsn;
+	}
+	xfs_iunlock(ip, XFS_ILOCK_SHARED);
+
+	if (lsn)
+		error = _xfs_log_force_lsn(mp, lsn, XFS_LOG_SYNC, &log_flushed);
+
+	/*
+	 * If we only have a single device, and the log force about was
+	 * a no-op we might have to flush the data device cache here.
+	 * This can only happen for fdatasync/O_DSYNC if we were overwriting
+	 * an already allocated file and thus do not have any metadata to
+	 * commit.
+	 */
+	if ((mp->m_flags & XFS_MOUNT_BARRIER) &&
+	    mp->m_logdev_targp == mp->m_ddev_targp &&
+	    !XFS_IS_REALTIME_INODE(ip) &&
+	    !log_flushed)
+		xfs_blkdev_issue_flush(mp->m_ddev_targp);
+
+	return error;
+}
+
+STATIC ssize_t
+xfs_file_read_iter(
+	struct kiocb		*iocb,
+	struct iov_iter		*to)
+{
+	struct file		*file = iocb->ki_filp;
+	struct inode		*inode = file->f_mapping->host;
+	struct xfs_inode	*ip = XFS_I(inode);
+	struct xfs_mount	*mp = ip->i_mount;
+	size_t			size = iov_iter_count(to);
+	ssize_t			ret = 0;
+	int			ioflags = 0;
+	xfs_fsize_t		n;
+	loff_t			pos = iocb->ki_pos;
+
+	XFS_STATS_INC(xs_read_calls);
+
+	if (unlikely(iocb->ki_flags & IOCB_DIRECT))
+		ioflags |= XFS_IO_ISDIRECT;
+	if (file->f_mode & FMODE_NOCMTIME)
+		ioflags |= XFS_IO_INVIS;
+
+	if (unlikely(ioflags & XFS_IO_ISDIRECT)) {
+		xfs_buftarg_t	*target =
+			XFS_IS_REALTIME_INODE(ip) ?
+				mp->m_rtdev_targp : mp->m_ddev_targp;
+		/* DIO must be aligned to device logical sector size */
+		if ((pos | size) & target->bt_logical_sectormask) {
+			if (pos == i_size_read(inode))
+				return 0;
+			return -EINVAL;
+		}
+	}
+
+	n = mp->m_super->s_maxbytes - pos;
+	if (n <= 0 || size == 0)
+		return 0;
+
+	if (n < size)
+		size = n;
+
+	if (XFS_FORCED_SHUTDOWN(mp))
+		return -EIO;
+
+	/*
+	 * Locking is a bit tricky here. If we take an exclusive lock
+	 * for direct IO, we effectively serialise all new concurrent
+	 * read IO to this file and block it behind IO that is currently in
+	 * progress because IO in progress holds the IO lock shared. We only
+	 * need to hold the lock exclusive to blow away the page cache, so
+	 * only take lock exclusively if the page cache needs invalidation.
+	 * This allows the normal direct IO case of no page cache pages to
+	 * proceeed concurrently without serialisation.
+	 */
+	xfs_rw_ilock(ip, XFS_IOLOCK_SHARED);
+	if ((ioflags & XFS_IO_ISDIRECT) && inode->i_mapping->nrpages) {
+		xfs_rw_iunlock(ip, XFS_IOLOCK_SHARED);
+		xfs_rw_ilock(ip, XFS_IOLOCK_EXCL);
+
+		if (inode->i_mapping->nrpages) {
+			ret = filemap_write_and_wait_range(
+							VFS_I(ip)->i_mapping,
+							pos, pos + size - 1);
+			if (ret) {
+				xfs_rw_iunlock(ip, XFS_IOLOCK_EXCL);
+				return ret;
+			}
+
+			/*
+			 * Invalidate whole pages. This can return an error if
+			 * we fail to invalidate a page, but this should never
+			 * happen on XFS. Warn if it does fail.
+			 */
+			ret = invalidate_inode_pages2_range(VFS_I(ip)->i_mapping,
+					pos >> PAGE_CACHE_SHIFT,
+					(pos + size - 1) >> PAGE_CACHE_SHIFT);
+			WARN_ON_ONCE(ret);
+			ret = 0;
+		}
+		xfs_rw_ilock_demote(ip, XFS_IOLOCK_EXCL);
+	}
+
+	trace_xfs_file_read(ip, size, pos, ioflags);
+
+	ret = generic_file_read_iter(iocb, to);
+	if (ret > 0)
+		XFS_STATS_ADD(xs_read_bytes, ret);
+
+	xfs_rw_iunlock(ip, XFS_IOLOCK_SHARED);
+	return ret;
+}
+
+STATIC ssize_t
+xfs_file_splice_read(
+	struct file		*infilp,
+	loff_t			*ppos,
+	struct pipe_inode_info	*pipe,
+	size_t			count,
+	unsigned int		flags)
+{
+	struct xfs_inode	*ip = XFS_I(infilp->f_mapping->host);
+	int			ioflags = 0;
+	ssize_t			ret;
+
+	XFS_STATS_INC(xs_read_calls);
+
+	if (infilp->f_mode & FMODE_NOCMTIME)
+		ioflags |= XFS_IO_INVIS;
+
+	if (XFS_FORCED_SHUTDOWN(ip->i_mount))
+		return -EIO;
+
+	xfs_rw_ilock(ip, XFS_IOLOCK_SHARED);
+
+	trace_xfs_file_splice_read(ip, count, *ppos, ioflags);
+
+	ret = generic_file_splice_read(infilp, ppos, pipe, count, flags);
+	if (ret > 0)
+		XFS_STATS_ADD(xs_read_bytes, ret);
+
+	xfs_rw_iunlock(ip, XFS_IOLOCK_SHARED);
+	return ret;
+}
+
+/*
+ * This routine is called to handle zeroing any space in the last block of the
+ * file that is beyond the EOF.  We do this since the size is being increased
+ * without writing anything to that block and we don't want to read the
+ * garbage on the disk.
+ */
+STATIC int				/* error (positive) */
+xfs_zero_last_block(
+	struct xfs_inode	*ip,
+	xfs_fsize_t		offset,
+	xfs_fsize_t		isize,
+	bool			*did_zeroing)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+	xfs_fileoff_t		last_fsb = XFS_B_TO_FSBT(mp, isize);
+	int			zero_offset = XFS_B_FSB_OFFSET(mp, isize);
+	int			zero_len;
+	int			nimaps = 1;
+	int			error = 0;
+	struct xfs_bmbt_irec	imap;
+
+	xfs_ilock(ip, XFS_ILOCK_EXCL);
+	error = xfs_bmapi_read(ip, last_fsb, 1, &imap, &nimaps, 0);
+	xfs_iunlock(ip, XFS_ILOCK_EXCL);
+	if (error)
+		return error;
+
+	ASSERT(nimaps > 0);
+
+	/*
+	 * If the block underlying isize is just a hole, then there
+	 * is nothing to zero.
+	 */
+	if (imap.br_startblock == HOLESTARTBLOCK)
+		return 0;
+
+	zero_len = mp->m_sb.sb_blocksize - zero_offset;
+	if (isize + zero_len > offset)
+		zero_len = offset - isize;
+	*did_zeroing = true;
+	return xfs_iozero(ip, isize, zero_len);
+}
+
+/*
+ * Zero any on disk space between the current EOF and the new, larger EOF.
+ *
+ * This handles the normal case of zeroing the remainder of the last block in
+ * the file and the unusual case of zeroing blocks out beyond the size of the
+ * file.  This second case only happens with fixed size extents and when the
+ * system crashes before the inode size was updated but after blocks were
+ * allocated.
+ *
+ * Expects the iolock to be held exclusive, and will take the ilock internally.
+ */
+int					/* error (positive) */
+xfs_zero_eof(
+	struct xfs_inode	*ip,
+	xfs_off_t		offset,		/* starting I/O offset */
+	xfs_fsize_t		isize,		/* current inode size */
+	bool			*did_zeroing)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+	xfs_fileoff_t		start_zero_fsb;
+	xfs_fileoff_t		end_zero_fsb;
+	xfs_fileoff_t		zero_count_fsb;
+	xfs_fileoff_t		last_fsb;
+	xfs_fileoff_t		zero_off;
+	xfs_fsize_t		zero_len;
+	int			nimaps;
+	int			error = 0;
+	struct xfs_bmbt_irec	imap;
+
+	ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
+	ASSERT(offset > isize);
+
+	/*
+	 * First handle zeroing the block on which isize resides.
+	 *
+	 * We only zero a part of that block so it is handled specially.
+	 */
+	if (XFS_B_FSB_OFFSET(mp, isize) != 0) {
+		error = xfs_zero_last_block(ip, offset, isize, did_zeroing);
+		if (error)
+			return error;
+	}
+
+	/*
+	 * Calculate the range between the new size and the old where blocks
+	 * needing to be zeroed may exist.
+	 *
+	 * To get the block where the last byte in the file currently resides,
+	 * we need to subtract one from the size and truncate back to a block
+	 * boundary.  We subtract 1 in case the size is exactly on a block
+	 * boundary.
+	 */
+	last_fsb = isize ? XFS_B_TO_FSBT(mp, isize - 1) : (xfs_fileoff_t)-1;
+	start_zero_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)isize);
+	end_zero_fsb = XFS_B_TO_FSBT(mp, offset - 1);
+	ASSERT((xfs_sfiloff_t)last_fsb < (xfs_sfiloff_t)start_zero_fsb);
+	if (last_fsb == end_zero_fsb) {
+		/*
+		 * The size was only incremented on its last block.
+		 * We took care of that above, so just return.
+		 */
+		return 0;
+	}
+
+	ASSERT(start_zero_fsb <= end_zero_fsb);
+	while (start_zero_fsb <= end_zero_fsb) {
+		nimaps = 1;
+		zero_count_fsb = end_zero_fsb - start_zero_fsb + 1;
+
+		xfs_ilock(ip, XFS_ILOCK_EXCL);
+		error = xfs_bmapi_read(ip, start_zero_fsb, zero_count_fsb,
+					  &imap, &nimaps, 0);
+		xfs_iunlock(ip, XFS_ILOCK_EXCL);
+		if (error)
+			return error;
+
+		ASSERT(nimaps > 0);
+
+		if (imap.br_state == XFS_EXT_UNWRITTEN ||
+		    imap.br_startblock == HOLESTARTBLOCK) {
+			start_zero_fsb = imap.br_startoff + imap.br_blockcount;
+			ASSERT(start_zero_fsb <= (end_zero_fsb + 1));
+			continue;
+		}
+
+		/*
+		 * There are blocks we need to zero.
+		 */
+		zero_off = XFS_FSB_TO_B(mp, start_zero_fsb);
+		zero_len = XFS_FSB_TO_B(mp, imap.br_blockcount);
+
+		if ((zero_off + zero_len) > offset)
+			zero_len = offset - zero_off;
+
+		error = xfs_iozero(ip, zero_off, zero_len);
+		if (error)
+			return error;
+
+		*did_zeroing = true;
+		start_zero_fsb = imap.br_startoff + imap.br_blockcount;
+		ASSERT(start_zero_fsb <= (end_zero_fsb + 1));
+	}
+
+	return 0;
+}
+
+/*
+ * Common pre-write limit and setup checks.
+ *
+ * Called with the iolocked held either shared and exclusive according to
+ * @iolock, and returns with it held.  Might upgrade the iolock to exclusive
+ * if called for a direct write beyond i_size.
+ */
+STATIC ssize_t
+xfs_file_aio_write_checks(
+	struct kiocb		*iocb,
+	struct iov_iter		*from,
+	int			*iolock)
+{
+	struct file		*file = iocb->ki_filp;
+	struct inode		*inode = file->f_mapping->host;
+	struct xfs_inode	*ip = XFS_I(inode);
+	ssize_t			error = 0;
+	size_t			count = iov_iter_count(from);
+
+restart:
+	error = generic_write_checks(iocb, from);
+	if (error <= 0)
+		return error;
+
+	error = xfs_break_layouts(inode, iolock, true);
+	if (error)
+		return error;
+
+	/*
+	 * If the offset is beyond the size of the file, we need to zero any
+	 * blocks that fall between the existing EOF and the start of this
+	 * write.  If zeroing is needed and we are currently holding the
+	 * iolock shared, we need to update it to exclusive which implies
+	 * having to redo all checks before.
+	 *
+	 * We need to serialise against EOF updates that occur in IO
+	 * completions here. We want to make sure that nobody is changing the
+	 * size while we do this check until we have placed an IO barrier (i.e.
+	 * hold the XFS_IOLOCK_EXCL) that prevents new IO from being dispatched.
+	 * The spinlock effectively forms a memory barrier once we have the
+	 * XFS_IOLOCK_EXCL so we are guaranteed to see the latest EOF value
+	 * and hence be able to correctly determine if we need to run zeroing.
+	 */
+	spin_lock(&ip->i_flags_lock);
+	if (iocb->ki_pos > i_size_read(inode)) {
+		bool	zero = false;
+
+		spin_unlock(&ip->i_flags_lock);
+		if (*iolock == XFS_IOLOCK_SHARED) {
+			xfs_rw_iunlock(ip, *iolock);
+			*iolock = XFS_IOLOCK_EXCL;
+			xfs_rw_ilock(ip, *iolock);
+			iov_iter_reexpand(from, count);
+
+			/*
+			 * We now have an IO submission barrier in place, but
+			 * AIO can do EOF updates during IO completion and hence
+			 * we now need to wait for all of them to drain. Non-AIO
+			 * DIO will have drained before we are given the
+			 * XFS_IOLOCK_EXCL, and so for most cases this wait is a
+			 * no-op.
+			 */
+			inode_dio_wait(inode);
+			goto restart;
+		}
+		error = xfs_zero_eof(ip, iocb->ki_pos, i_size_read(inode), &zero);
+		if (error)
+			return error;
+	} else
+		spin_unlock(&ip->i_flags_lock);
+
+	/*
+	 * Updating the timestamps will grab the ilock again from
+	 * xfs_fs_dirty_inode, so we have to call it after dropping the
+	 * lock above.  Eventually we should look into a way to avoid
+	 * the pointless lock roundtrip.
+	 */
+	if (likely(!(file->f_mode & FMODE_NOCMTIME))) {
+		error = file_update_time(file);
+		if (error)
+			return error;
+	}
+
+	/*
+	 * If we're writing the file then make sure to clear the setuid and
+	 * setgid bits if the process is not being run by root.  This keeps
+	 * people from modifying setuid and setgid binaries.
+	 */
+	return file_remove_suid(file);
+}
+
+/*
+ * xfs_file_dio_aio_write - handle direct IO writes
+ *
+ * Lock the inode appropriately to prepare for and issue a direct IO write.
+ * By separating it from the buffered write path we remove all the tricky to
+ * follow locking changes and looping.
+ *
+ * If there are cached pages or we're extending the file, we need IOLOCK_EXCL
+ * until we're sure the bytes at the new EOF have been zeroed and/or the cached
+ * pages are flushed out.
+ *
+ * In most cases the direct IO writes will be done holding IOLOCK_SHARED
+ * allowing them to be done in parallel with reads and other direct IO writes.
+ * However, if the IO is not aligned to filesystem blocks, the direct IO layer
+ * needs to do sub-block zeroing and that requires serialisation against other
+ * direct IOs to the same block. In this case we need to serialise the
+ * submission of the unaligned IOs so that we don't get racing block zeroing in
+ * the dio layer.  To avoid the problem with aio, we also need to wait for
+ * outstanding IOs to complete so that unwritten extent conversion is completed
+ * before we try to map the overlapping block. This is currently implemented by
+ * hitting it with a big hammer (i.e. inode_dio_wait()).
+ *
+ * Returns with locks held indicated by @iolock and errors indicated by
+ * negative return values.
+ */
+STATIC ssize_t
+xfs_file_dio_aio_write(
+	struct kiocb		*iocb,
+	struct iov_iter		*from)
+{
+	struct file		*file = iocb->ki_filp;
+	struct address_space	*mapping = file->f_mapping;
+	struct inode		*inode = mapping->host;
+	struct xfs_inode	*ip = XFS_I(inode);
+	struct xfs_mount	*mp = ip->i_mount;
+	ssize_t			ret = 0;
+	int			unaligned_io = 0;
+	int			iolock;
+	size_t			count = iov_iter_count(from);
+	loff_t			pos = iocb->ki_pos;
+	loff_t			end;
+	struct iov_iter		data;
+	struct xfs_buftarg	*target = XFS_IS_REALTIME_INODE(ip) ?
+					mp->m_rtdev_targp : mp->m_ddev_targp;
+
+	/* DIO must be aligned to device logical sector size */
+	if ((pos | count) & target->bt_logical_sectormask)
+		return -EINVAL;
+
+	/* "unaligned" here means not aligned to a filesystem block */
+	if ((pos & mp->m_blockmask) || ((pos + count) & mp->m_blockmask))
+		unaligned_io = 1;
+
+	/*
+	 * We don't need to take an exclusive lock unless there page cache needs
+	 * to be invalidated or unaligned IO is being executed. We don't need to
+	 * consider the EOF extension case here because
+	 * xfs_file_aio_write_checks() will relock the inode as necessary for
+	 * EOF zeroing cases and fill out the new inode size as appropriate.
+	 */
+	if (unaligned_io || mapping->nrpages)
+		iolock = XFS_IOLOCK_EXCL;
+	else
+		iolock = XFS_IOLOCK_SHARED;
+	xfs_rw_ilock(ip, iolock);
+
+	/*
+	 * Recheck if there are cached pages that need invalidate after we got
+	 * the iolock to protect against other threads adding new pages while
+	 * we were waiting for the iolock.
+	 */
+	if (mapping->nrpages && iolock == XFS_IOLOCK_SHARED) {
+		xfs_rw_iunlock(ip, iolock);
+		iolock = XFS_IOLOCK_EXCL;
+		xfs_rw_ilock(ip, iolock);
+	}
+
+	ret = xfs_file_aio_write_checks(iocb, from, &iolock);
+	if (ret)
+		goto out;
+	count = iov_iter_count(from);
+	pos = iocb->ki_pos;
+	end = pos + count - 1;
+
+	if (mapping->nrpages) {
+		ret = filemap_write_and_wait_range(VFS_I(ip)->i_mapping,
+						   pos, end);
+		if (ret)
+			goto out;
+		/*
+		 * Invalidate whole pages. This can return an error if
+		 * we fail to invalidate a page, but this should never
+		 * happen on XFS. Warn if it does fail.
+		 */
+		ret = invalidate_inode_pages2_range(VFS_I(ip)->i_mapping,
+					pos >> PAGE_CACHE_SHIFT,
+					end >> PAGE_CACHE_SHIFT);
+		WARN_ON_ONCE(ret);
+		ret = 0;
+	}
+
+	/*
+	 * If we are doing unaligned IO, wait for all other IO to drain,
+	 * otherwise demote the lock if we had to flush cached pages
+	 */
+	if (unaligned_io)
+		inode_dio_wait(inode);
+	else if (iolock == XFS_IOLOCK_EXCL) {
+		xfs_rw_ilock_demote(ip, XFS_IOLOCK_EXCL);
+		iolock = XFS_IOLOCK_SHARED;
+	}
+
+	trace_xfs_file_direct_write(ip, count, iocb->ki_pos, 0);
+
+	data = *from;
+	ret = mapping->a_ops->direct_IO(iocb, &data, pos);
+
+	/* see generic_file_direct_write() for why this is necessary */
+	if (mapping->nrpages) {
+		invalidate_inode_pages2_range(mapping,
+					      pos >> PAGE_CACHE_SHIFT,
+					      end >> PAGE_CACHE_SHIFT);
+	}
+
+	if (ret > 0) {
+		pos += ret;
+		iov_iter_advance(from, ret);
+		iocb->ki_pos = pos;
+	}
+out:
+	xfs_rw_iunlock(ip, iolock);
+
+	/* No fallback to buffered IO on errors for XFS. */
+	ASSERT(ret < 0 || ret == count);
+	return ret;
+}
+
+STATIC ssize_t
+xfs_file_buffered_aio_write(
+	struct kiocb		*iocb,
+	struct iov_iter		*from)
+{
+	struct file		*file = iocb->ki_filp;
+	struct address_space	*mapping = file->f_mapping;
+	struct inode		*inode = mapping->host;
+	struct xfs_inode	*ip = XFS_I(inode);
+	ssize_t			ret;
+	int			enospc = 0;
+	int			iolock = XFS_IOLOCK_EXCL;
+
+	xfs_rw_ilock(ip, iolock);
+
+	ret = xfs_file_aio_write_checks(iocb, from, &iolock);
+	if (ret)
+		goto out;
+
+	/* We can write back this queue in page reclaim */
+	current->backing_dev_info = inode_to_bdi(inode);
+
+write_retry:
+	trace_xfs_file_buffered_write(ip, iov_iter_count(from),
+				      iocb->ki_pos, 0);
+	ret = generic_perform_write(file, from, iocb->ki_pos);
+	if (likely(ret >= 0))
+		iocb->ki_pos += ret;
+
+	/*
+	 * If we hit a space limit, try to free up some lingering preallocated
+	 * space before returning an error. In the case of ENOSPC, first try to
+	 * write back all dirty inodes to free up some of the excess reserved
+	 * metadata space. This reduces the chances that the eofblocks scan
+	 * waits on dirty mappings. Since xfs_flush_inodes() is serialized, this
+	 * also behaves as a filter to prevent too many eofblocks scans from
+	 * running at the same time.
+	 */
+	if (ret == -EDQUOT && !enospc) {
+		enospc = xfs_inode_free_quota_eofblocks(ip);
+		if (enospc)
+			goto write_retry;
+	} else if (ret == -ENOSPC && !enospc) {
+		struct xfs_eofblocks eofb = {0};
+
+		enospc = 1;
+		xfs_flush_inodes(ip->i_mount);
+		eofb.eof_scan_owner = ip->i_ino; /* for locking */
+		eofb.eof_flags = XFS_EOF_FLAGS_SYNC;
+		xfs_icache_free_eofblocks(ip->i_mount, &eofb);
+		goto write_retry;
+	}
+
+	current->backing_dev_info = NULL;
+out:
+	xfs_rw_iunlock(ip, iolock);
+	return ret;
+}
+
+STATIC ssize_t
+xfs_file_write_iter(
+	struct kiocb		*iocb,
+	struct iov_iter		*from)
+{
+	struct file		*file = iocb->ki_filp;
+	struct address_space	*mapping = file->f_mapping;
+	struct inode		*inode = mapping->host;
+	struct xfs_inode	*ip = XFS_I(inode);
+	ssize_t			ret;
+	size_t			ocount = iov_iter_count(from);
+
+	XFS_STATS_INC(xs_write_calls);
+
+	if (ocount == 0)
+		return 0;
+
+	if (XFS_FORCED_SHUTDOWN(ip->i_mount))
+		return -EIO;
+
+	if (unlikely(iocb->ki_flags & IOCB_DIRECT))
+		ret = xfs_file_dio_aio_write(iocb, from);
+	else
+		ret = xfs_file_buffered_aio_write(iocb, from);
+
+	if (ret > 0) {
+		ssize_t err;
+
+		XFS_STATS_ADD(xs_write_bytes, ret);
+
+		/* Handle various SYNC-type writes */
+		err = generic_write_sync(file, iocb->ki_pos - ret, ret);
+		if (err < 0)
+			ret = err;
+	}
+	return ret;
+}
+
+#define	XFS_FALLOC_FL_SUPPORTED						\
+		(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |		\
+		 FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_ZERO_RANGE |	\
+		 FALLOC_FL_INSERT_RANGE)
+
+STATIC long
+xfs_file_fallocate(
+	struct file		*file,
+	int			mode,
+	loff_t			offset,
+	loff_t			len)
+{
+	struct inode		*inode = file_inode(file);
+	struct xfs_inode	*ip = XFS_I(inode);
+	long			error;
+	enum xfs_prealloc_flags	flags = 0;
+	uint			iolock = XFS_IOLOCK_EXCL;
+	loff_t			new_size = 0;
+	bool			do_file_insert = 0;
+
+	if (!S_ISREG(inode->i_mode))
+		return -EINVAL;
+	if (mode & ~XFS_FALLOC_FL_SUPPORTED)
+		return -EOPNOTSUPP;
+
+	xfs_ilock(ip, iolock);
+	error = xfs_break_layouts(inode, &iolock, false);
+	if (error)
+		goto out_unlock;
+
+	xfs_ilock(ip, XFS_MMAPLOCK_EXCL);
+	iolock |= XFS_MMAPLOCK_EXCL;
+
+	if (mode & FALLOC_FL_PUNCH_HOLE) {
+		error = xfs_free_file_space(ip, offset, len);
+		if (error)
+			goto out_unlock;
+	} else if (mode & FALLOC_FL_COLLAPSE_RANGE) {
+		unsigned blksize_mask = (1 << inode->i_blkbits) - 1;
+
+		if (offset & blksize_mask || len & blksize_mask) {
+			error = -EINVAL;
+			goto out_unlock;
+		}
+
+		/*
+		 * There is no need to overlap collapse range with EOF,
+		 * in which case it is effectively a truncate operation
+		 */
+		if (offset + len >= i_size_read(inode)) {
+			error = -EINVAL;
+			goto out_unlock;
+		}
+
+		new_size = i_size_read(inode) - len;
+
+		error = xfs_collapse_file_space(ip, offset, len);
+		if (error)
+			goto out_unlock;
+	} else if (mode & FALLOC_FL_INSERT_RANGE) {
+		unsigned blksize_mask = (1 << inode->i_blkbits) - 1;
+
+		new_size = i_size_read(inode) + len;
+		if (offset & blksize_mask || len & blksize_mask) {
+			error = -EINVAL;
+			goto out_unlock;
+		}
+
+		/* check the new inode size does not wrap through zero */
+		if (new_size > inode->i_sb->s_maxbytes) {
+			error = -EFBIG;
+			goto out_unlock;
+		}
+
+		/* Offset should be less than i_size */
+		if (offset >= i_size_read(inode)) {
+			error = -EINVAL;
+			goto out_unlock;
+		}
+		do_file_insert = 1;
+	} else {
+		flags |= XFS_PREALLOC_SET;
+
+		if (!(mode & FALLOC_FL_KEEP_SIZE) &&
+		    offset + len > i_size_read(inode)) {
+			new_size = offset + len;
+			error = inode_newsize_ok(inode, new_size);
+			if (error)
+				goto out_unlock;
+		}
+
+		if (mode & FALLOC_FL_ZERO_RANGE)
+			error = xfs_zero_file_space(ip, offset, len);
+		else
+			error = xfs_alloc_file_space(ip, offset, len,
+						     XFS_BMAPI_PREALLOC);
+		if (error)
+			goto out_unlock;
+	}
+
+	if (file->f_flags & O_DSYNC)
+		flags |= XFS_PREALLOC_SYNC;
+
+	error = xfs_update_prealloc_flags(ip, flags);
+	if (error)
+		goto out_unlock;
+
+	/* Change file size if needed */
+	if (new_size) {
+		struct iattr iattr;
+
+		iattr.ia_valid = ATTR_SIZE;
+		iattr.ia_size = new_size;
+		error = xfs_setattr_size(ip, &iattr);
+		if (error)
+			goto out_unlock;
+	}
+
+	/*
+	 * Perform hole insertion now that the file size has been
+	 * updated so that if we crash during the operation we don't
+	 * leave shifted extents past EOF and hence losing access to
+	 * the data that is contained within them.
+	 */
+	if (do_file_insert)
+		error = xfs_insert_file_space(ip, offset, len);
+
+out_unlock:
+	xfs_iunlock(ip, iolock);
+	return error;
+}
+
+
+STATIC int
+xfs_file_open(
+	struct inode	*inode,
+	struct file	*file)
+{
+	if (!(file->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
+		return -EFBIG;
+	if (XFS_FORCED_SHUTDOWN(XFS_M(inode->i_sb)))
+		return -EIO;
+	return 0;
+}
+
+STATIC int
+xfs_dir_open(
+	struct inode	*inode,
+	struct file	*file)
+{
+	struct xfs_inode *ip = XFS_I(inode);
+	int		mode;
+	int		error;
+
+	error = xfs_file_open(inode, file);
+	if (error)
+		return error;
+
+	/*
+	 * If there are any blocks, read-ahead block 0 as we're almost
+	 * certain to have the next operation be a read there.
+	 */
+	mode = xfs_ilock_data_map_shared(ip);
+	if (ip->i_d.di_nextents > 0)
+		xfs_dir3_data_readahead(ip, 0, -1);
+	xfs_iunlock(ip, mode);
+	return 0;
+}
+
+STATIC int
+xfs_file_release(
+	struct inode	*inode,
+	struct file	*filp)
+{
+	return xfs_release(XFS_I(inode));
+}
+
+STATIC int
+xfs_file_readdir(
+	struct file	*file,
+	struct dir_context *ctx)
+{
+	struct inode	*inode = file_inode(file);
+	xfs_inode_t	*ip = XFS_I(inode);
+	size_t		bufsize;
+
+	/*
+	 * The Linux API doesn't pass down the total size of the buffer
+	 * we read into down to the filesystem.  With the filldir concept
+	 * it's not needed for correct information, but the XFS dir2 leaf
+	 * code wants an estimate of the buffer size to calculate it's
+	 * readahead window and size the buffers used for mapping to
+	 * physical blocks.
+	 *
+	 * Try to give it an estimate that's good enough, maybe at some
+	 * point we can change the ->readdir prototype to include the
+	 * buffer size.  For now we use the current glibc buffer size.
+	 */
+	bufsize = (size_t)min_t(loff_t, 32768, ip->i_d.di_size);
+
+	return xfs_readdir(ip, ctx, bufsize);
+}
+
+STATIC int
+xfs_file_mmap(
+	struct file	*filp,
+	struct vm_area_struct *vma)
+{
+	vma->vm_ops = &xfs_file_vm_ops;
+
+	file_accessed(filp);
+	return 0;
+}
+
+/*
+ * This type is designed to indicate the type of offset we would like
+ * to search from page cache for xfs_seek_hole_data().
+ */
+enum {
+	HOLE_OFF = 0,
+	DATA_OFF,
+};
+
+/*
+ * Lookup the desired type of offset from the given page.
+ *
+ * On success, return true and the offset argument will point to the
+ * start of the region that was found.  Otherwise this function will
+ * return false and keep the offset argument unchanged.
+ */
+STATIC bool
+xfs_lookup_buffer_offset(
+	struct page		*page,
+	loff_t			*offset,
+	unsigned int		type)
+{
+	loff_t			lastoff = page_offset(page);
+	bool			found = false;
+	struct buffer_head	*bh, *head;
+
+	bh = head = page_buffers(page);
+	do {
+		/*
+		 * Unwritten extents that have data in the page
+		 * cache covering them can be identified by the
+		 * BH_Unwritten state flag.  Pages with multiple
+		 * buffers might have a mix of holes, data and
+		 * unwritten extents - any buffer with valid
+		 * data in it should have BH_Uptodate flag set
+		 * on it.
+		 */
+		if (buffer_unwritten(bh) ||
+		    buffer_uptodate(bh)) {
+			if (type == DATA_OFF)
+				found = true;
+		} else {
+			if (type == HOLE_OFF)
+				found = true;
+		}
+
+		if (found) {
+			*offset = lastoff;
+			break;
+		}
+		lastoff += bh->b_size;
+	} while ((bh = bh->b_this_page) != head);
+
+	return found;
+}
+
+/*
+ * This routine is called to find out and return a data or hole offset
+ * from the page cache for unwritten extents according to the desired
+ * type for xfs_seek_hole_data().
+ *
+ * The argument offset is used to tell where we start to search from the
+ * page cache.  Map is used to figure out the end points of the range to
+ * lookup pages.
+ *
+ * Return true if the desired type of offset was found, and the argument
+ * offset is filled with that address.  Otherwise, return false and keep
+ * offset unchanged.
+ */
+STATIC bool
+xfs_find_get_desired_pgoff(
+	struct inode		*inode,
+	struct xfs_bmbt_irec	*map,
+	unsigned int		type,
+	loff_t			*offset)
+{
+	struct xfs_inode	*ip = XFS_I(inode);
+	struct xfs_mount	*mp = ip->i_mount;
+	struct pagevec		pvec;
+	pgoff_t			index;
+	pgoff_t			end;
+	loff_t			endoff;
+	loff_t			startoff = *offset;
+	loff_t			lastoff = startoff;
+	bool			found = false;
+
+	pagevec_init(&pvec, 0);
+
+	index = startoff >> PAGE_CACHE_SHIFT;
+	endoff = XFS_FSB_TO_B(mp, map->br_startoff + map->br_blockcount);
+	end = endoff >> PAGE_CACHE_SHIFT;
+	do {
+		int		want;
+		unsigned	nr_pages;
+		unsigned int	i;
+
+		want = min_t(pgoff_t, end - index, PAGEVEC_SIZE);
+		nr_pages = pagevec_lookup(&pvec, inode->i_mapping, index,
+					  want);
+		/*
+		 * No page mapped into given range.  If we are searching holes
+		 * and if this is the first time we got into the loop, it means
+		 * that the given offset is landed in a hole, return it.
+		 *
+		 * If we have already stepped through some block buffers to find
+		 * holes but they all contains data.  In this case, the last
+		 * offset is already updated and pointed to the end of the last
+		 * mapped page, if it does not reach the endpoint to search,
+		 * that means there should be a hole between them.
+		 */
+		if (nr_pages == 0) {
+			/* Data search found nothing */
+			if (type == DATA_OFF)
+				break;
+
+			ASSERT(type == HOLE_OFF);
+			if (lastoff == startoff || lastoff < endoff) {
+				found = true;
+				*offset = lastoff;
+			}
+			break;
+		}
+
+		/*
+		 * At lease we found one page.  If this is the first time we
+		 * step into the loop, and if the first page index offset is
+		 * greater than the given search offset, a hole was found.
+		 */
+		if (type == HOLE_OFF && lastoff == startoff &&
+		    lastoff < page_offset(pvec.pages[0])) {
+			found = true;
+			break;
+		}
+
+		for (i = 0; i < nr_pages; i++) {
+			struct page	*page = pvec.pages[i];
+			loff_t		b_offset;
+
+			/*
+			 * At this point, the page may be truncated or
+			 * invalidated (changing page->mapping to NULL),
+			 * or even swizzled back from swapper_space to tmpfs
+			 * file mapping. However, page->index will not change
+			 * because we have a reference on the page.
+			 *
+			 * Searching done if the page index is out of range.
+			 * If the current offset is not reaches the end of
+			 * the specified search range, there should be a hole
+			 * between them.
+			 */
+			if (page->index > end) {
+				if (type == HOLE_OFF && lastoff < endoff) {
+					*offset = lastoff;
+					found = true;
+				}
+				goto out;
+			}
+
+			lock_page(page);
+			/*
+			 * Page truncated or invalidated(page->mapping == NULL).
+			 * We can freely skip it and proceed to check the next
+			 * page.
+			 */
+			if (unlikely(page->mapping != inode->i_mapping)) {
+				unlock_page(page);
+				continue;
+			}
+
+			if (!page_has_buffers(page)) {
+				unlock_page(page);
+				continue;
+			}
+
+			found = xfs_lookup_buffer_offset(page, &b_offset, type);
+			if (found) {
+				/*
+				 * The found offset may be less than the start
+				 * point to search if this is the first time to
+				 * come here.
+				 */
+				*offset = max_t(loff_t, startoff, b_offset);
+				unlock_page(page);
+				goto out;
+			}
+
+			/*
+			 * We either searching data but nothing was found, or
+			 * searching hole but found a data buffer.  In either
+			 * case, probably the next page contains the desired
+			 * things, update the last offset to it so.
+			 */
+			lastoff = page_offset(page) + PAGE_SIZE;
+			unlock_page(page);
+		}
+
+		/*
+		 * The number of returned pages less than our desired, search
+		 * done.  In this case, nothing was found for searching data,
+		 * but we found a hole behind the last offset.
+		 */
+		if (nr_pages < want) {
+			if (type == HOLE_OFF) {
+				*offset = lastoff;
+				found = true;
+			}
+			break;
+		}
+
+		index = pvec.pages[i - 1]->index + 1;
+		pagevec_release(&pvec);
+	} while (index <= end);
+
+out:
+	pagevec_release(&pvec);
+	return found;
+}
+
+STATIC loff_t
+xfs_seek_hole_data(
+	struct file		*file,
+	loff_t			start,
+	int			whence)
+{
+	struct inode		*inode = file->f_mapping->host;
+	struct xfs_inode	*ip = XFS_I(inode);
+	struct xfs_mount	*mp = ip->i_mount;
+	loff_t			uninitialized_var(offset);
+	xfs_fsize_t		isize;
+	xfs_fileoff_t		fsbno;
+	xfs_filblks_t		end;
+	uint			lock;
+	int			error;
+
+	if (XFS_FORCED_SHUTDOWN(mp))
+		return -EIO;
+
+	lock = xfs_ilock_data_map_shared(ip);
+
+	isize = i_size_read(inode);
+	if (start >= isize) {
+		error = -ENXIO;
+		goto out_unlock;
+	}
+
+	/*
+	 * Try to read extents from the first block indicated
+	 * by fsbno to the end block of the file.
+	 */
+	fsbno = XFS_B_TO_FSBT(mp, start);
+	end = XFS_B_TO_FSB(mp, isize);
+
+	for (;;) {
+		struct xfs_bmbt_irec	map[2];
+		int			nmap = 2;
+		unsigned int		i;
+
+		error = xfs_bmapi_read(ip, fsbno, end - fsbno, map, &nmap,
+				       XFS_BMAPI_ENTIRE);
+		if (error)
+			goto out_unlock;
+
+		/* No extents at given offset, must be beyond EOF */
+		if (nmap == 0) {
+			error = -ENXIO;
+			goto out_unlock;
+		}
+
+		for (i = 0; i < nmap; i++) {
+			offset = max_t(loff_t, start,
+				       XFS_FSB_TO_B(mp, map[i].br_startoff));
+
+			/* Landed in the hole we wanted? */
+			if (whence == SEEK_HOLE &&
+			    map[i].br_startblock == HOLESTARTBLOCK)
+				goto out;
+
+			/* Landed in the data extent we wanted? */
+			if (whence == SEEK_DATA &&
+			    (map[i].br_startblock == DELAYSTARTBLOCK ||
+			     (map[i].br_state == XFS_EXT_NORM &&
+			      !isnullstartblock(map[i].br_startblock))))
+				goto out;
+
+			/*
+			 * Landed in an unwritten extent, try to search
+			 * for hole or data from page cache.
+			 */
+			if (map[i].br_state == XFS_EXT_UNWRITTEN) {
+				if (xfs_find_get_desired_pgoff(inode, &map[i],
+				      whence == SEEK_HOLE ? HOLE_OFF : DATA_OFF,
+							&offset))
+					goto out;
+			}
+		}
+
+		/*
+		 * We only received one extent out of the two requested. This
+		 * means we've hit EOF and didn't find what we are looking for.
+		 */
+		if (nmap == 1) {
+			/*
+			 * If we were looking for a hole, set offset to
+			 * the end of the file (i.e., there is an implicit
+			 * hole at the end of any file).
+		 	 */
+			if (whence == SEEK_HOLE) {
+				offset = isize;
+				break;
+			}
+			/*
+			 * If we were looking for data, it's nowhere to be found
+			 */
+			ASSERT(whence == SEEK_DATA);
+			error = -ENXIO;
+			goto out_unlock;
+		}
+
+		ASSERT(i > 1);
+
+		/*
+		 * Nothing was found, proceed to the next round of search
+		 * if the next reading offset is not at or beyond EOF.
+		 */
+		fsbno = map[i - 1].br_startoff + map[i - 1].br_blockcount;
+		start = XFS_FSB_TO_B(mp, fsbno);
+		if (start >= isize) {
+			if (whence == SEEK_HOLE) {
+				offset = isize;
+				break;
+			}
+			ASSERT(whence == SEEK_DATA);
+			error = -ENXIO;
+			goto out_unlock;
+		}
+	}
+
+out:
+	/*
+	 * If at this point we have found the hole we wanted, the returned
+	 * offset may be bigger than the file size as it may be aligned to
+	 * page boundary for unwritten extents.  We need to deal with this
+	 * situation in particular.
+	 */
+	if (whence == SEEK_HOLE)
+		offset = min_t(loff_t, offset, isize);
+	offset = vfs_setpos(file, offset, inode->i_sb->s_maxbytes);
+
+out_unlock:
+	xfs_iunlock(ip, lock);
+
+	if (error)
+		return error;
+	return offset;
+}
+
+STATIC loff_t
+xfs_file_llseek(
+	struct file	*file,
+	loff_t		offset,
+	int		whence)
+{
+	switch (whence) {
+	case SEEK_END:
+	case SEEK_CUR:
+	case SEEK_SET:
+		return generic_file_llseek(file, offset, whence);
+	case SEEK_HOLE:
+	case SEEK_DATA:
+		return xfs_seek_hole_data(file, offset, whence);
+	default:
+		return -EINVAL;
+	}
+}
+
+/*
+ * Locking for serialisation of IO during page faults. This results in a lock
+ * ordering of:
+ *
+ * mmap_sem (MM)
+ *   i_mmap_lock (XFS - truncate serialisation)
+ *     page_lock (MM)
+ *       i_lock (XFS - extent map serialisation)
+ */
+STATIC int
+xfs_filemap_fault(
+	struct vm_area_struct	*vma,
+	struct vm_fault		*vmf)
+{
+	struct xfs_inode	*ip = XFS_I(vma->vm_file->f_mapping->host);
+	int			error;
+
+	trace_xfs_filemap_fault(ip);
+
+	xfs_ilock(ip, XFS_MMAPLOCK_SHARED);
+	error = filemap_fault(vma, vmf);
+	xfs_iunlock(ip, XFS_MMAPLOCK_SHARED);
+
+	return error;
+}
+
+/*
+ * mmap()d file has taken write protection fault and is being made writable. We
+ * can set the page state up correctly for a writable page, which means we can
+ * do correct delalloc accounting (ENOSPC checking!) and unwritten extent
+ * mapping.
+ */
+STATIC int
+xfs_filemap_page_mkwrite(
+	struct vm_area_struct	*vma,
+	struct vm_fault		*vmf)
+{
+	struct xfs_inode	*ip = XFS_I(vma->vm_file->f_mapping->host);
+	int			error;
+
+	trace_xfs_filemap_page_mkwrite(ip);
+
+	xfs_ilock(ip, XFS_MMAPLOCK_SHARED);
+	error = block_page_mkwrite(vma, vmf, xfs_get_blocks);
+	xfs_iunlock(ip, XFS_MMAPLOCK_SHARED);
+
+	return error;
+}
+
+const struct file_operations xfs_file_operations = {
+	.llseek		= xfs_file_llseek,
+	.read_iter	= xfs_file_read_iter,
+	.write_iter	= xfs_file_write_iter,
+	.splice_read	= xfs_file_splice_read,
+	.splice_write	= iter_file_splice_write,
+	.unlocked_ioctl	= xfs_file_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= xfs_file_compat_ioctl,
+#endif
+	.mmap		= xfs_file_mmap,
+	.open		= xfs_file_open,
+	.release	= xfs_file_release,
+	.fsync		= xfs_file_fsync,
+	.fallocate	= xfs_file_fallocate,
+};
+
+const struct file_operations xfs_dir_file_operations = {
+	.open		= xfs_dir_open,
+	.read		= generic_read_dir,
+	.iterate	= xfs_file_readdir,
+	.llseek		= generic_file_llseek,
+	.unlocked_ioctl	= xfs_file_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= xfs_file_compat_ioctl,
+#endif
+	.fsync		= xfs_dir_fsync,
+};
+
+static const struct vm_operations_struct xfs_file_vm_ops = {
+	.fault		= xfs_filemap_fault,
+	.map_pages	= filemap_map_pages,
+	.page_mkwrite	= xfs_filemap_page_mkwrite,
+};