patch-2.4.27 linux-2.4.27/fs/xfs/linux-2.4/xfs_lrw.c

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diff -urN linux-2.4.26/fs/xfs/linux-2.4/xfs_lrw.c linux-2.4.27/fs/xfs/linux-2.4/xfs_lrw.c
@@ -0,0 +1,982 @@
+/*
+ * 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_refcache.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 "xfs_iomap.h"
+
+#include <linux/capability.h>
+
+
+#if defined(XFS_RW_TRACE)
+void
+xfs_rw_enter_trace(
+	int		tag,
+	xfs_iocore_t	*io,
+	const char	*buf,
+	size_t		size,
+	loff_t		offset,
+	int		ioflags)
+{
+	xfs_inode_t	*ip = XFS_IO_INODE(io);
+
+	if (ip->i_rwtrace == NULL)
+		return;
+	ktrace_enter(ip->i_rwtrace,
+		(void *)(unsigned long)tag,
+		(void *)ip,
+		(void *)((unsigned long)((ip->i_d.di_size >> 32) & 0xffffffff)),
+		(void *)((unsigned long)(ip->i_d.di_size & 0xffffffff)),
+		(void *)(__psint_t)buf,
+		(void *)((unsigned long)size),
+		(void *)((unsigned long)((offset >> 32) & 0xffffffff)),
+		(void *)((unsigned long)(offset & 0xffffffff)),
+		(void *)((unsigned long)ioflags),
+		(void *)((unsigned long)((io->io_new_size >> 32) & 0xffffffff)),
+		(void *)((unsigned long)(io->io_new_size & 0xffffffff)),
+		(void *)NULL,
+		(void *)NULL,
+		(void *)NULL,
+		(void *)NULL,
+		(void *)NULL);
+}
+
+void
+xfs_inval_cached_trace(
+	xfs_iocore_t	*io,
+	xfs_off_t	offset,
+	xfs_off_t	len,
+	xfs_off_t	first,
+	xfs_off_t	last)
+{
+	xfs_inode_t	*ip = XFS_IO_INODE(io);
+
+	if (ip->i_rwtrace == NULL)
+		return;
+	ktrace_enter(ip->i_rwtrace,
+		(void *)(__psint_t)XFS_INVAL_CACHED,
+		(void *)ip,
+		(void *)((unsigned long)((offset >> 32) & 0xffffffff)),
+		(void *)((unsigned long)(offset & 0xffffffff)),
+		(void *)((unsigned long)((len >> 32) & 0xffffffff)),
+		(void *)((unsigned long)(len & 0xffffffff)),
+		(void *)((unsigned long)((first >> 32) & 0xffffffff)),
+		(void *)((unsigned long)(first & 0xffffffff)),
+		(void *)((unsigned long)((last >> 32) & 0xffffffff)),
+		(void *)((unsigned long)(last & 0xffffffff)),
+		(void *)NULL,
+		(void *)NULL,
+		(void *)NULL,
+		(void *)NULL,
+		(void *)NULL,
+		(void *)NULL);
+}
+#endif
+
+/*
+ *	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 > i_size_read(ip))
+				i_size_write(ip, pos < end_size ? pos : end_size);
+		}
+
+unlock:
+		kunmap(page);
+		unlock_page(page);
+		page_cache_release(page);
+		if (status)
+			break;
+	} while (count);
+
+	return (-status);
+}
+
+/*
+ * xfs_inval_cached_pages
+ * 
+ * This routine is responsible for keeping direct I/O and buffered I/O
+ * somewhat coherent.  From here we make sure that we're at least
+ * temporarily holding the inode I/O lock exclusively and then call
+ * the page cache to flush and invalidate any cached pages.  If there
+ * are no cached pages this routine will be very quick.
+ */
+void
+xfs_inval_cached_pages(
+	vnode_t		*vp,
+	xfs_iocore_t	*io,
+	xfs_off_t	offset,
+	int		write,
+	int		relock)
+{
+	xfs_mount_t	*mp;
+
+	if (!VN_CACHED(vp)) {
+		return;
+	}
+
+	mp = io->io_mount;
+
+	/*
+	 * We need to get the I/O lock exclusively in order
+	 * to safely invalidate pages and mappings.
+	 */
+	if (relock) {
+		XFS_IUNLOCK(mp, io, XFS_IOLOCK_SHARED);
+		XFS_ILOCK(mp, io, XFS_IOLOCK_EXCL);
+	}
+
+	/* Writing beyond EOF creates a hole that must be zeroed */
+	if (write && (offset > XFS_SIZE(mp, io))) {
+		xfs_fsize_t	isize;
+
+		XFS_ILOCK(mp, io, XFS_ILOCK_EXCL|XFS_EXTSIZE_RD);
+		isize = XFS_SIZE(mp, io);
+		if (offset > isize) {
+			xfs_zero_eof(vp, io, offset, isize, offset);
+		}
+		XFS_IUNLOCK(mp, io, XFS_ILOCK_EXCL|XFS_EXTSIZE_RD);
+	}
+
+	xfs_inval_cached_trace(io, offset, -1, ctooff(offtoct(offset)), -1);
+	VOP_FLUSHINVAL_PAGES(vp, ctooff(offtoct(offset)), -1, FI_REMAPF_LOCKED);
+	if (relock) {
+		XFS_ILOCK_DEMOTE(mp, io, XFS_IOLOCK_EXCL);
+	}
+}
+
+ssize_t			/* bytes read, or (-)  error */
+xfs_read(
+	bhv_desc_t      *bdp,
+	struct file	*file,
+	char		*buf,
+	size_t		size,
+	loff_t		*offset,
+	int		ioflags,
+	cred_t          *credp)
+{
+	ssize_t		ret;
+	xfs_fsize_t	n;
+	xfs_inode_t	*ip;
+	xfs_mount_t	*mp;
+
+	ip = XFS_BHVTOI(bdp);
+	mp = ip->i_mount;
+
+	XFS_STATS_INC(xs_read_calls);
+
+	if (unlikely(ioflags & IO_ISDIRECT)) {
+		if ((ssize_t)size < 0)
+			return -XFS_ERROR(EINVAL);
+		if (((__psint_t)buf & BBMASK) ||
+		    (*offset & mp->m_blockmask) ||
+		    (size & mp->m_blockmask)) {
+			if (*offset >= ip->i_d.di_size) {
+				return (0);
+			}
+			return -XFS_ERROR(EINVAL);
+		}
+	}
+
+	n = XFS_MAXIOFFSET(mp) - *offset;
+	if ((n <= 0) || (size == 0))
+		return 0;
+
+	if (n < size)
+		size = n;
+
+	if (XFS_FORCED_SHUTDOWN(mp)) {
+		return -EIO;
+	}
+
+	if (!(ioflags & IO_ISLOCKED))
+		xfs_ilock(ip, XFS_IOLOCK_SHARED);
+
+	if (DM_EVENT_ENABLED(BHV_TO_VNODE(bdp)->v_vfsp, ip, DM_EVENT_READ) &&
+	    !(ioflags & IO_INVIS)) {
+		int error;
+		vrwlock_t locktype = VRWLOCK_READ;
+		int dmflags = FILP_DELAY_FLAG(file) | DM_SEM_FLAG_RD(ioflags);
+
+		error = XFS_SEND_DATA(mp, DM_EVENT_READ, BHV_TO_VNODE(bdp), *offset, size,
+				      dmflags, &locktype);
+		if (error) {
+			if (!(ioflags & IO_ISLOCKED))
+				xfs_iunlock(ip, XFS_IOLOCK_SHARED);
+			return -error;
+		}
+	}
+
+	if (unlikely(ioflags & IO_ISDIRECT)) {
+		xfs_rw_enter_trace(XFS_DIORD_ENTER, &ip->i_iocore,
+					buf, size, *offset, ioflags);
+		ret = (*offset < ip->i_d.di_size) ?
+			do_generic_direct_read(file, buf, size, offset) : 0;
+		UPDATE_ATIME(file->f_dentry->d_inode);
+	} else {
+		xfs_rw_enter_trace(XFS_READ_ENTER, &ip->i_iocore,
+					buf, size, *offset, ioflags);
+		ret = generic_file_read(file, buf, size, offset);
+	}
+
+	if (!(ioflags & IO_ISLOCKED))
+		xfs_iunlock(ip, XFS_IOLOCK_SHARED);
+
+	XFS_STATS_ADD(xs_read_bytes, ret);
+
+	if (unlikely(ioflags & IO_INVIS)) {
+		/* generic_file_read updates the atime but we need to
+		 * undo that because this I/O was supposed to be invisible.
+		 */
+		struct inode *inode = LINVFS_GET_IP(BHV_TO_VNODE(bdp));
+		inode->i_atime = ip->i_d.di_atime.t_sec;
+	} else {
+		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_state == XFS_EXT_UNWRITTEN ||
+		    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 char	*buf,
+	size_t		size,
+	loff_t		*offset,
+	int		ioflags,
+	cred_t          *credp)
+{
+	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_iocore_t    *io;
+	vnode_t		*vp;
+	int		iolock;
+	int		eventsent = 0;
+	vrwlock_t	locktype;
+
+	XFS_STATS_INC(xs_write_calls);
+
+	vp = BHV_TO_VNODE(bdp);
+	xip = XFS_BHVTOI(bdp);
+
+	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 (unlikely(ioflags & IO_ISDIRECT)) {
+		if (((__psint_t)buf & BBMASK) ||
+		    (*offset & mp->m_blockmask) ||
+		    (size  & mp->m_blockmask)) {
+			return XFS_ERROR(-EINVAL);
+		}
+		iolock = XFS_IOLOCK_SHARED;
+		locktype = VRWLOCK_WRITE_DIRECT;
+	} else {
+		if (io->io_flags & XFS_IOCORE_RT)
+			return XFS_ERROR(-EINVAL);
+		iolock = XFS_IOLOCK_EXCL;
+		locktype = VRWLOCK_WRITE;
+	}
+
+	if (ioflags & IO_ISLOCKED)
+		iolock = 0;
+
+	xfs_ilock(xip, XFS_ILOCK_EXCL|iolock);
+
+	isize = xip->i_d.di_size;
+	limit = XFS_MAXIOFFSET(mp);
+
+	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) &&
+	    !(ioflags & IO_INVIS) && !eventsent)) {
+		loff_t		savedsize = *offset;
+		int dmflags = FILP_DELAY_FLAG(file) | DM_SEM_FLAG_RD(ioflags);
+
+		xfs_iunlock(xip, XFS_ILOCK_EXCL);
+		error = XFS_SEND_DATA(xip->i_mount, DM_EVENT_WRITE, vp,
+				      *offset, size,
+				      dmflags, &locktype);
+		if (error) {
+			if (iolock) 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;
+		}
+	}
+
+	/*
+	 * 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 (!(ioflags & IO_ISDIRECT) && (*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 & S_ISUID) ||
+	    ((xip->i_d.di_mode & (S_ISGID | S_IXGRP)) ==
+		(S_ISGID | S_IXGRP))) &&
+	     !capable(CAP_FSETID)) {
+		error = xfs_write_clear_setuid(xip);
+		if (error) {
+			xfs_iunlock(xip, iolock);
+			return -error;
+		}
+	}
+
+
+	if ((ssize_t) size < 0) {
+		ret = -EINVAL;
+		goto error;
+	}
+
+	if (!access_ok(VERIFY_READ, buf, size)) {
+		ret = -EINVAL;
+		goto error;
+	}
+
+retry:
+	if (unlikely(ioflags & IO_ISDIRECT)) {
+		xfs_inval_cached_pages(vp, io, *offset, 1, 1);
+		xfs_rw_enter_trace(XFS_DIOWR_ENTER,
+					io, buf, size, *offset, ioflags);
+		ret = do_generic_direct_write(file, buf, size, offset);
+	} else {
+		xfs_rw_enter_trace(XFS_WRITE_ENTER,
+					io, buf, size, *offset, ioflags);
+		ret = do_generic_file_write(file, buf, size, offset);
+	}
+
+	if (unlikely(ioflags & IO_INVIS)) {
+		/* generic_file_write updates the mtime/ctime but we need
+		 * to undo that because this I/O was supposed to be
+		 * invisible.
+		 */
+		struct inode	*inode = LINVFS_GET_IP(vp);
+		inode->i_mtime = xip->i_d.di_mtime.t_sec;
+		inode->i_ctime = xip->i_d.di_ctime.t_sec;
+	} else {
+		xfs_ichgtime(xip, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
+	}
+
+	if ((ret == -ENOSPC) &&
+	    DM_EVENT_ENABLED(vp->v_vfsp, xip, DM_EVENT_NOSPACE) &&
+	    !(ioflags & IO_INVIS)) {
+
+		xfs_rwunlock(bdp, locktype);
+		error = XFS_SEND_NAMESP(xip->i_mount, DM_EVENT_NOSPACE, vp,
+				DM_RIGHT_NULL, vp, 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;
+	}
+
+error:
+	if (ret <= 0) {
+		if (iolock)
+			xfs_rwunlock(bdp, locktype);
+		return ret;
+	}
+
+	XFS_STATS_ADD(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);
+
+			xip->i_d.di_size = *offset;
+			i_size_write(inode, *offset);
+			xip->i_update_core = 1;
+			xip->i_update_size = 1;
+			mark_inode_dirty_sync(inode);
+		}
+		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, NULL);
+				xfs_iunlock(xip, XFS_ILOCK_EXCL);
+			}
+		}
+	} /* (ioflags & O_SYNC) */
+
+	/*
+	 * If we are coming from an nfsd thread then insert into the
+	 * reference cache.
+	 */
+
+	if (!strcmp(current->comm, "nfsd"))
+		xfs_refcache_insert(xip);
+
+	/* Drop lock this way - the old refcache release is in here */
+	if (iolock)
+		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,
+	xfs_iomap_t	*iomapp,
+	int		*niomaps)
+{
+	xfs_inode_t	*ip = XFS_BHVTOI(bdp);
+	xfs_iocore_t	*io = &ip->i_iocore;
+
+	ASSERT((ip->i_d.di_mode & S_IFMT) == S_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, iomapp, niomaps);
+}
+
+/*
+ * 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));
+}
+
+/*
+ * If the underlying (data/log/rt) device is readonly, there are some
+ * operations that cannot proceed.
+ */
+int
+xfs_dev_is_read_only(
+	xfs_mount_t		*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))) {
+		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;
+}
FUNET's LINUX-ADM group, linux-adm@nic.funet.fi
TCL-scripts by Sam Shen (who was at: slshen@lbl.gov)