/*
 * Copyright (c) 2000-2003 Silicon Graphics, Inc.  All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2 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.
 *
 * Further, this software is distributed without any warranty that it is
 * free of the rightful claim of any third person regarding infringement
 * or the like.  Any license provided herein, whether implied or
 * otherwise, applies only to this software file.  Patent licenses, if
 * any, provided herein do not apply to combinations of this program with
 * other software, or any other product whatsoever.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write the Free Software Foundation, Inc., 59
 * Temple Place - Suite 330, Boston MA 02111-1307, USA.
 *
 * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
 * Mountain View, CA  94043, or:
 *
 * http://www.sgi.com
 *
 * For further information regarding this notice, see:
 *
 * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
 */
/*
 *  fs/xfs/linux/xfs_lrw.c (Linux Read Write stuff)
 *
 */

#include "xfs.h"

#include "xfs_fs.h"
#include "xfs_inum.h"
#include "xfs_log.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_dir.h"
#include "xfs_dir2.h"
#include "xfs_alloc.h"
#include "xfs_dmapi.h"
#include "xfs_quota.h"
#include "xfs_mount.h"
#include "xfs_alloc_btree.h"
#include "xfs_bmap_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_btree.h"
#include "xfs_ialloc.h"
#include "xfs_attr_sf.h"
#include "xfs_dir_sf.h"
#include "xfs_dir2_sf.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_bmap.h"
#include "xfs_bit.h"
#include "xfs_rtalloc.h"
#include "xfs_error.h"
#include "xfs_itable.h"
#include "xfs_rw.h"
#include "xfs_acl.h"
#include "xfs_cap.h"
#include "xfs_mac.h"
#include "xfs_attr.h"
#include "xfs_inode_item.h"
#include "xfs_buf_item.h"
#include "xfs_utils.h"

#include <linux/capability.h>


/*
 *	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.
 */
STATIC int
xfs_iozero(
	struct inode		*ip,	/* inode			*/
	loff_t			pos,	/* offset in file		*/
	size_t			count,	/* size of data to zero		*/
	loff_t			end_size)	/* max file size to set */
{
	unsigned		bytes;
	struct page		*page;
	struct address_space	*mapping;
	char			*kaddr;
	int			status;

	mapping = ip->i_mapping;
	do {
		unsigned long index, offset;

		offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
		index = pos >> PAGE_CACHE_SHIFT;
		bytes = PAGE_CACHE_SIZE - offset;
		if (bytes > count)
			bytes = count;

		status = -ENOMEM;
		page = grab_cache_page(mapping, index);
		if (!page)
			break;

		kaddr = kmap(page);
		status = mapping->a_ops->prepare_write(NULL, page, offset,
							offset + bytes);
		if (status) {
			goto unlock;
		}

		memset((void *) (kaddr + offset), 0, bytes);
		flush_dcache_page(page);
		status = mapping->a_ops->commit_write(NULL, page, offset,
							offset + bytes);
		if (!status) {
			pos += bytes;
			count -= bytes;
			if (pos > ip->i_size)
				ip->i_size = pos < end_size ? pos : end_size;
		}

unlock:
		kunmap(page);
		unlock_page(page);
		page_cache_release(page);
		if (status)
			break;
	} while (count);

	return (-status);
}

ssize_t			/* bytes read, or (-)  error */
xfs_read(
	bhv_desc_t		*bdp,
	struct file		*filp,
	const struct iovec	*iovp,
	unsigned long		segs,
	loff_t			*offp,
	cred_t			*credp)
{
	size_t			size = 0;
	ssize_t			ret;
	xfs_fsize_t		n;
	xfs_inode_t		*ip;
	xfs_mount_t		*mp;
	vnode_t			*vp;
	unsigned long		seg;
	int			direct = (filp->f_flags & O_DIRECT);
	int			invisible = (filp->f_mode & FINVIS);

	ip = XFS_BHVTOI(bdp);
	vp = BHV_TO_VNODE(bdp);
	mp = ip->i_mount;
	vn_trace_entry(vp, "xfs_read", (inst_t *)__return_address);

	XFS_STATS_INC(xfsstats.xs_read_calls);

	/* START copy & waste from filemap.c */
	for (seg = 0; seg < segs; seg++) {
		const struct iovec *iv = &iovp[seg];

		/*
		 * If any segment has a negative length, or the cumulative
		 * length ever wraps negative then return -EINVAL.
		 */
		size += iv->iov_len;
		if (unlikely((ssize_t)(size|iv->iov_len) < 0))
			return XFS_ERROR(-EINVAL);
		if (direct) {	/* XFS specific check */
			if ((__psint_t)iv->iov_base & BBMASK) {
				if (*offp == ip->i_d.di_size)
					return 0;
				return XFS_ERROR(-EINVAL);
			}
		}
		if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len))
			continue;
		if (seg == 0)
			return XFS_ERROR(-EFAULT);
		segs = seg;
		break;
	}
	/* END copy & waste from filemap.c */

	if (direct) {
		if ((*offp & mp->m_blockmask) ||
		    (size & mp->m_blockmask)) {
			if (*offp == ip->i_d.di_size) {
				return (0);
			}
			return -XFS_ERROR(EINVAL);
		}
	}

	n = XFS_MAX_FILE_OFFSET - *offp;
	if ((n <= 0) || (size == 0))
		return 0;

	if (n < size)
		size = n;

	if (XFS_FORCED_SHUTDOWN(mp)) {
		return -EIO;
	}

	xfs_ilock(ip, XFS_IOLOCK_SHARED);

	if (DM_EVENT_ENABLED(vp->v_vfsp, ip, DM_EVENT_READ) && !invisible) {
		int error;
		vrwlock_t locktype = VRWLOCK_READ;

		error = XFS_SEND_DATA(mp, DM_EVENT_READ, bdp, *offp, size,
				      FILP_DELAY_FLAG(filp), &locktype);
		if (error) {
			xfs_iunlock(ip, XFS_IOLOCK_SHARED);
			return -error;
		}
	}

	ret = generic_file_readv(filp, iovp, segs, offp);
	xfs_iunlock(ip, XFS_IOLOCK_SHARED);

	XFS_STATS_ADD(xfsstats.xs_read_bytes, ret);

	if (!invisible)
		xfs_ichgtime(ip, XFS_ICHGTIME_ACC);

	return ret;
}

ssize_t
xfs_sendfile(
	bhv_desc_t		*bdp,
	struct file		*filp,
	loff_t			*offp,
	size_t			count,
	read_actor_t		actor,
	void			*target,
	cred_t			*credp)
{
	ssize_t			ret;
	xfs_fsize_t		n;
	xfs_inode_t		*ip;
	xfs_mount_t		*mp;
	vnode_t			*vp;
	int			invisible = (filp->f_mode & FINVIS);

	ip = XFS_BHVTOI(bdp);
	vp = BHV_TO_VNODE(bdp);
	mp = ip->i_mount;
	vn_trace_entry(vp, "xfs_sendfile", (inst_t *)__return_address);

	XFS_STATS_INC(xfsstats.xs_read_calls);

	n = XFS_MAX_FILE_OFFSET - *offp;
	if ((n <= 0) || (count == 0))
		return 0;

	if (n < count)
		count = n;

	if (XFS_FORCED_SHUTDOWN(ip->i_mount))
		return -EIO;

	xfs_ilock(ip, XFS_IOLOCK_SHARED);
	if (DM_EVENT_ENABLED(vp->v_vfsp, ip, DM_EVENT_READ) && !invisible) {
		vrwlock_t locktype = VRWLOCK_READ;
		int error;

		error = XFS_SEND_DATA(mp, DM_EVENT_READ, bdp, *offp, count,
				      FILP_DELAY_FLAG(filp), &locktype);
		if (error) {
			xfs_iunlock(ip, XFS_IOLOCK_SHARED);
			return -error;
		}
	}
	ret = generic_file_sendfile(filp, offp, count, actor, target);
	xfs_iunlock(ip, XFS_IOLOCK_SHARED);

	XFS_STATS_ADD(xfsstats.xs_read_bytes, ret);
	if (!invisible)
		xfs_ichgtime(ip, XFS_ICHGTIME_ACC);
	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 anyone to read the garbage on the disk.
 */
STATIC int				/* error (positive) */
xfs_zero_last_block(
	struct inode	*ip,
	xfs_iocore_t	*io,
	xfs_off_t	offset,
	xfs_fsize_t	isize,
	xfs_fsize_t	end_size)
{
	xfs_fileoff_t	last_fsb;
	xfs_mount_t	*mp;
	int		nimaps;
	int		zero_offset;
	int		zero_len;
	int		isize_fsb_offset;
	int		error = 0;
	xfs_bmbt_irec_t	imap;
	loff_t		loff;
	size_t		lsize;

	ASSERT(ismrlocked(io->io_lock, MR_UPDATE) != 0);
	ASSERT(offset > isize);

	mp = io->io_mount;

	isize_fsb_offset = XFS_B_FSB_OFFSET(mp, isize);
	if (isize_fsb_offset == 0) {
		/*
		 * There are no extra bytes in the last block on disk to
		 * zero, so return.
		 */
		return 0;
	}

	last_fsb = XFS_B_TO_FSBT(mp, isize);
	nimaps = 1;
	error = XFS_BMAPI(mp, NULL, io, last_fsb, 1, 0, NULL, 0, &imap,
			  &nimaps, NULL);
	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 the part of the last block beyond the EOF, and write it
	 * out sync.  We need to drop the ilock while we do this so we
	 * don't deadlock when the buffer cache calls back to us.
	 */
	XFS_IUNLOCK(mp, io, XFS_ILOCK_EXCL| XFS_EXTSIZE_RD);
	loff = XFS_FSB_TO_B(mp, last_fsb);
	lsize = XFS_FSB_TO_B(mp, 1);

	zero_offset = isize_fsb_offset;
	zero_len = mp->m_sb.sb_blocksize - isize_fsb_offset;

	error = xfs_iozero(ip, loff + zero_offset, zero_len, end_size);

	XFS_ILOCK(mp, io, XFS_ILOCK_EXCL|XFS_EXTSIZE_RD);
	ASSERT(error >= 0);
	return error;
}

/*
 * 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.  If fill is set,
 * then any holes in the range are filled and zeroed.  If not, the holes
 * are left alone as holes.
 */

int					/* error (positive) */
xfs_zero_eof(
	vnode_t		*vp,
	xfs_iocore_t	*io,
	xfs_off_t	offset,		/* starting I/O offset */
	xfs_fsize_t	isize,		/* current inode size */
	xfs_fsize_t	end_size)	/* terminal inode size */
{
	struct inode	*ip = LINVFS_GET_IP(vp);
	xfs_fileoff_t	start_zero_fsb;
	xfs_fileoff_t	end_zero_fsb;
	xfs_fileoff_t	prev_zero_fsb;
	xfs_fileoff_t	zero_count_fsb;
	xfs_fileoff_t	last_fsb;
	xfs_extlen_t	buf_len_fsb;
	xfs_extlen_t	prev_zero_count;
	xfs_mount_t	*mp;
	int		nimaps;
	int		error = 0;
	xfs_bmbt_irec_t	imap;
	loff_t		loff;
	size_t		lsize;

	ASSERT(ismrlocked(io->io_lock, MR_UPDATE));
	ASSERT(ismrlocked(io->io_iolock, MR_UPDATE));

	mp = io->io_mount;

	/*
	 * First handle zeroing the block on which isize resides.
	 * We only zero a part of that block so it is handled specially.
	 */
	error = xfs_zero_last_block(ip, io, offset, isize, end_size);
	if (error) {
		ASSERT(ismrlocked(io->io_lock, MR_UPDATE));
		ASSERT(ismrlocked(io->io_iolock, MR_UPDATE));
		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);
	prev_zero_fsb = NULLFILEOFF;
	prev_zero_count = 0;
	while (start_zero_fsb <= end_zero_fsb) {
		nimaps = 1;
		zero_count_fsb = end_zero_fsb - start_zero_fsb + 1;
		error = XFS_BMAPI(mp, NULL, io, start_zero_fsb, zero_count_fsb,
				  0, NULL, 0, &imap, &nimaps, NULL);
		if (error) {
			ASSERT(ismrlocked(io->io_lock, MR_UPDATE));
			ASSERT(ismrlocked(io->io_iolock, MR_UPDATE));
			return error;
		}
		ASSERT(nimaps > 0);

		if (imap.br_startblock == HOLESTARTBLOCK) {
			/*
			 * This loop handles initializing pages that were
			 * partially initialized by the code below this
			 * loop. It basically zeroes the part of the page
			 * that sits on a hole and sets the page as P_HOLE
			 * and calls remapf if it is a mapped file.
			 */
			prev_zero_fsb = NULLFILEOFF;
			prev_zero_count = 0;
			start_zero_fsb = imap.br_startoff +
					 imap.br_blockcount;
			ASSERT(start_zero_fsb <= (end_zero_fsb + 1));
			continue;
		}

		/*
		 * There are blocks in the range requested.
		 * Zero them a single write at a time.  We actually
		 * don't zero the entire range returned if it is
		 * too big and simply loop around to get the rest.
		 * That is not the most efficient thing to do, but it
		 * is simple and this path should not be exercised often.
		 */
		buf_len_fsb = XFS_FILBLKS_MIN(imap.br_blockcount,
					      mp->m_writeio_blocks << 8);
		/*
		 * Drop the inode lock while we're doing the I/O.
		 * We'll still have the iolock to protect us.
		 */
		XFS_IUNLOCK(mp, io, XFS_ILOCK_EXCL|XFS_EXTSIZE_RD);

		loff = XFS_FSB_TO_B(mp, start_zero_fsb);
		lsize = XFS_FSB_TO_B(mp, buf_len_fsb);

		error = xfs_iozero(ip, loff, lsize, end_size);

		if (error) {
			goto out_lock;
		}

		prev_zero_fsb = start_zero_fsb;
		prev_zero_count = buf_len_fsb;
		start_zero_fsb = imap.br_startoff + buf_len_fsb;
		ASSERT(start_zero_fsb <= (end_zero_fsb + 1));

		XFS_ILOCK(mp, io, XFS_ILOCK_EXCL|XFS_EXTSIZE_RD);
	}

	return 0;

out_lock:

	XFS_ILOCK(mp, io, XFS_ILOCK_EXCL|XFS_EXTSIZE_RD);
	ASSERT(error >= 0);
	return error;
}

ssize_t				/* bytes written, or (-) error */
xfs_write(
	bhv_desc_t		*bdp,
	struct file		*file,
	const struct iovec	*iovp,
	unsigned long		segs,
	loff_t			*offset,
	cred_t			*credp)
{
	size_t			size = 0;
	xfs_inode_t		*xip;
	xfs_mount_t		*mp;
	ssize_t			ret;
	int			error = 0;
	xfs_fsize_t		isize, new_size;
	xfs_fsize_t		n, limit = XFS_MAX_FILE_OFFSET;
	xfs_iocore_t		*io;
	vnode_t			*vp;
	unsigned long		seg;
	int			iolock;
	int			direct = (file->f_flags & O_DIRECT);
	int			invisible = (file->f_mode & FINVIS);
	int			eventsent = 0;
	vrwlock_t		locktype;

	XFS_STATS_INC(xfsstats.xs_write_calls);

	vp = BHV_TO_VNODE(bdp);
	vn_trace_entry(vp, "xfs_write", (inst_t *)__return_address);
	xip = XFS_BHVTOI(bdp);

	/* START copy & waste from filemap.c */
	for (seg = 0; seg < segs; seg++) {
		const struct iovec *iv = &iovp[seg];

		/*
		 * If any segment has a negative length, or the cumulative
		 * length ever wraps negative then return -EINVAL.
		 */
		size += iv->iov_len;
		if (unlikely((ssize_t)(size|iv->iov_len) < 0))
			return XFS_ERROR(-EINVAL);
		if (direct) {	/* XFS specific check */
			if ((__psint_t)iv->iov_base & BBMASK)
				return XFS_ERROR(-EINVAL);
		}
		if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len))
			continue;
		if (seg == 0)
			return XFS_ERROR(-EFAULT);
		segs = seg;
		break;
	}
	/* END copy & waste from filemap.c */

	if (size == 0)
		return 0;

	io = &(xip->i_iocore);
	mp = io->io_mount;

	xfs_check_frozen(mp, bdp, XFS_FREEZE_WRITE);

	if (XFS_FORCED_SHUTDOWN(xip->i_mount)) {
		return -EIO;
	}

	if (direct) {
		if ((*offset & mp->m_blockmask) ||
		    (size & mp->m_blockmask)) {
			return XFS_ERROR(-EINVAL);
		}
		iolock = XFS_IOLOCK_SHARED;
		locktype = VRWLOCK_WRITE_DIRECT;
	} else {
		iolock = XFS_IOLOCK_EXCL;
		locktype = VRWLOCK_WRITE;
	}

	xfs_ilock(xip, XFS_ILOCK_EXCL|iolock);
	isize = xip->i_d.di_size;

	if (file->f_flags & O_APPEND)
		*offset = isize;

start:
	n = limit - *offset;
	if (n <= 0) {
		xfs_iunlock(xip, XFS_ILOCK_EXCL|iolock);
		return -EFBIG;
	}

	if (n < size)
		size = n;

	new_size = *offset + size;
	if (new_size > isize) {
		io->io_new_size = new_size;
	}

	if ((DM_EVENT_ENABLED(vp->v_vfsp, xip, DM_EVENT_WRITE) &&
	    !invisible && !eventsent)) {
		loff_t		savedsize = *offset;

		xfs_iunlock(xip, XFS_ILOCK_EXCL);
		error = XFS_SEND_DATA(xip->i_mount, DM_EVENT_WRITE, bdp,
				      *offset, size,
				      FILP_DELAY_FLAG(file), &locktype);
		if (error) {
			xfs_iunlock(xip, iolock);
			return -error;
		}
		xfs_ilock(xip, XFS_ILOCK_EXCL);
		eventsent = 1;

		/*
		 * The iolock was dropped and reaquired in XFS_SEND_DATA
		 * so we have to recheck the size when appending.
		 * We will only "goto start;" once, since having sent the
		 * event prevents another call to XFS_SEND_DATA, which is
		 * what allows the size to change in the first place.
		 */
		if ((file->f_flags & O_APPEND) &&
		    savedsize != xip->i_d.di_size) {
			*offset = isize = xip->i_d.di_size;
			goto start;
		}
	}

	/*
	 * On Linux, generic_file_write updates the times even if
	 * no data is copied in so long as the write had a size.
	 *
	 * We must update xfs' times since revalidate will overcopy xfs.
	 */
	if (size && !invisible)
		xfs_ichgtime(xip, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);

	/*
	 * If the offset is beyond the size of the file, we have a couple
	 * of things to do. First, if there is already space allocated
	 * we need to either create holes or zero the disk or ...
	 *
	 * If there is a page where the previous size lands, we need
	 * to zero it out up to the new size.
	 */

	if (!direct && (*offset > isize && isize)) {
		error = xfs_zero_eof(BHV_TO_VNODE(bdp), io, *offset,
			isize, *offset + size);
		if (error) {
			xfs_iunlock(xip, XFS_ILOCK_EXCL|iolock);
			return(-error);
		}
	}
	xfs_iunlock(xip, XFS_ILOCK_EXCL);

	/*
	 * 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.
	 */

	if (((xip->i_d.di_mode & ISUID) ||
	    ((xip->i_d.di_mode & (ISGID | (IEXEC >> 3))) ==
		(ISGID | (IEXEC >> 3)))) &&
	     !capable(CAP_FSETID)) {
		error = xfs_write_clear_setuid(xip);
		if (error) {
			xfs_iunlock(xip, iolock);
			return -error;
		}
	}

retry:
	if (direct) {
		xfs_inval_cached_pages(vp, &xip->i_iocore, *offset, 1, 1);
	}

	ret = generic_file_write_nolock(file, iovp, segs, offset);

	if ((ret == -ENOSPC) &&
	    DM_EVENT_ENABLED(vp->v_vfsp, xip, DM_EVENT_NOSPACE) && !invisible) {

		xfs_rwunlock(bdp, locktype);
		error = XFS_SEND_NAMESP(xip->i_mount, DM_EVENT_NOSPACE, bdp,
				DM_RIGHT_NULL, bdp, DM_RIGHT_NULL, NULL, NULL,
				0, 0, 0); /* Delay flag intentionally  unused */
		if (error)
			return -error;
		xfs_rwlock(bdp, locktype);
		*offset = xip->i_d.di_size;
		goto retry;

	}

	if (ret <= 0) {
		xfs_rwunlock(bdp, locktype);
		return ret;
	}

	XFS_STATS_ADD(xfsstats.xs_write_bytes, ret);

	if (*offset > xip->i_d.di_size) {
		xfs_ilock(xip, XFS_ILOCK_EXCL);
		if (*offset > xip->i_d.di_size) {
			struct inode	*inode = LINVFS_GET_IP(vp);

			inode->i_size = xip->i_d.di_size = *offset;
			xip->i_update_core = 1;
			xip->i_update_size = 1;
		}
		xfs_iunlock(xip, XFS_ILOCK_EXCL);
	}

	/* Handle various SYNC-type writes */
	if ((file->f_flags & O_SYNC) || IS_SYNC(file->f_dentry->d_inode)) {

		/*
		 * If we're treating this as O_DSYNC and we have not updated the
		 * size, force the log.
		 */

		if (!(mp->m_flags & XFS_MOUNT_OSYNCISOSYNC)
			&& !(xip->i_update_size)) {
			/*
			 * If an allocation transaction occurred
			 * without extending the size, then we have to force
			 * the log up the proper point to ensure that the
			 * allocation is permanent.  We can't count on
			 * the fact that buffered writes lock out direct I/O
			 * writes - the direct I/O write could have extended
			 * the size nontransactionally, then finished before
			 * we started.  xfs_write_file will think that the file
			 * didn't grow but the update isn't safe unless the
			 * size change is logged.
			 *
			 * Force the log if we've committed a transaction
			 * against the inode or if someone else has and
			 * the commit record hasn't gone to disk (e.g.
			 * the inode is pinned).  This guarantees that
			 * all changes affecting the inode are permanent
			 * when we return.
			 */

			xfs_inode_log_item_t *iip;
			xfs_lsn_t lsn;

			iip = xip->i_itemp;
			if (iip && iip->ili_last_lsn) {
				lsn = iip->ili_last_lsn;
				xfs_log_force(mp, lsn,
						XFS_LOG_FORCE | XFS_LOG_SYNC);
			} else if (xfs_ipincount(xip) > 0) {
				xfs_log_force(mp, (xfs_lsn_t)0,
						XFS_LOG_FORCE | XFS_LOG_SYNC);
			}

		} else {
			xfs_trans_t	*tp;

			/*
			 * O_SYNC or O_DSYNC _with_ a size update are handled
			 * the same way.
			 *
			 * If the write was synchronous then we need to make
			 * sure that the inode modification time is permanent.
			 * We'll have updated the timestamp above, so here
			 * we use a synchronous transaction to log the inode.
			 * It's not fast, but it's necessary.
			 *
			 * If this a dsync write and the size got changed
			 * non-transactionally, then we need to ensure that
			 * the size change gets logged in a synchronous
			 * transaction.
			 */

			tp = xfs_trans_alloc(mp, XFS_TRANS_WRITE_SYNC);
			if ((error = xfs_trans_reserve(tp, 0,
						      XFS_SWRITE_LOG_RES(mp),
						      0, 0, 0))) {
				/* Transaction reserve failed */
				xfs_trans_cancel(tp, 0);
			} else {
				/* Transaction reserve successful */
				xfs_ilock(xip, XFS_ILOCK_EXCL);
				xfs_trans_ijoin(tp, xip, XFS_ILOCK_EXCL);
				xfs_trans_ihold(tp, xip);
				xfs_trans_log_inode(tp, xip, XFS_ILOG_CORE);
				xfs_trans_set_sync(tp);
				error = xfs_trans_commit(tp, 0, (xfs_lsn_t)0);
				xfs_iunlock(xip, XFS_ILOCK_EXCL);
			}
		}
	} /* (ioflags & O_SYNC) */

	xfs_rwunlock(bdp, locktype);
	return(ret);
}

/*
 * All xfs metadata buffers except log state machine buffers
 * get this attached as their b_bdstrat callback function.
 * This is so that we can catch a buffer
 * after prematurely unpinning it to forcibly shutdown the filesystem.
 */
int
xfs_bdstrat_cb(struct xfs_buf *bp)
{
	xfs_mount_t	*mp;

	mp = XFS_BUF_FSPRIVATE3(bp, xfs_mount_t *);
	if (!XFS_FORCED_SHUTDOWN(mp)) {
		pagebuf_iorequest(bp);
		return 0;
	} else {
		xfs_buftrace("XFS__BDSTRAT IOERROR", bp);
		/*
		 * Metadata write that didn't get logged but
		 * written delayed anyway. These aren't associated
		 * with a transaction, and can be ignored.
		 */
		if (XFS_BUF_IODONE_FUNC(bp) == NULL &&
		    (XFS_BUF_ISREAD(bp)) == 0)
			return (xfs_bioerror_relse(bp));
		else
			return (xfs_bioerror(bp));
	}
}


int
xfs_bmap(bhv_desc_t	*bdp,
	xfs_off_t	offset,
	ssize_t		count,
	int		flags,
	page_buf_bmap_t	*pbmapp,
	int		*npbmaps)
{
	xfs_inode_t	*ip = XFS_BHVTOI(bdp);
	xfs_iocore_t	*io = &ip->i_iocore;

	ASSERT((ip->i_d.di_mode & IFMT) == IFREG);
	ASSERT(((ip->i_d.di_flags & XFS_DIFLAG_REALTIME) != 0) ==
	       ((ip->i_iocore.io_flags & XFS_IOCORE_RT) != 0));

	return xfs_iomap(io, offset, count, flags, pbmapp, npbmaps);
}

/*
 * Wrapper around bdstrat so that we can stop data
 * from going to disk in case we are shutting down the filesystem.
 * Typically user data goes thru this path; one of the exceptions
 * is the superblock.
 */
int
xfsbdstrat(
	struct xfs_mount	*mp,
	struct xfs_buf		*bp)
{
	ASSERT(mp);
	if (!XFS_FORCED_SHUTDOWN(mp)) {
		/* Grio redirection would go here
		 * if (XFS_BUF_IS_GRIO(bp)) {
		 */

		pagebuf_iorequest(bp);
		return 0;
	}

	xfs_buftrace("XFSBDSTRAT IOERROR", bp);
	return (xfs_bioerror_relse(bp));
}


void
XFS_bflush(xfs_buftarg_t *target)
{
	pagebuf_delwri_flush(target, PBDF_WAIT, NULL);
}

/*
 * If the underlying (log or data) device is readonly, there are some
 * operations that cannot proceed.
 */
int
xfs_dev_is_read_only(xfs_mount_t *mp, char *message)
{
	if (bdev_read_only(mp->m_ddev_targp->pbr_bdev) ||
	    bdev_read_only(mp->m_logdev_targp->pbr_bdev) ||
	   (mp->m_rtdev_targp && bdev_read_only(mp->m_rtdev_targp->pbr_bdev))) {
		cmn_err(CE_NOTE,
			"XFS: %s required on read-only device.", message);
		cmn_err(CE_NOTE,
			"XFS: write access unavailable, cannot proceed.");
		return EROFS;
	}

	return 0;
}
