fs/xfs/xfs_symlink.c - kernel/msm-4.19 - Gitiles

 /*
  * Copyright (c) 2000-2006 Silicon Graphics, Inc.
  * Copyright (c) 2012-2013 Red Hat, 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_format.h"
 #include "xfs_bit.h"
 #include "xfs_log.h"
 #include "xfs_trans.h"
 #include "xfs_sb.h"
 #include "xfs_ag.h"
 #include "xfs_mount.h"
 #include "xfs_da_btree.h"
 #include "xfs_dir2_format.h"
 #include "xfs_dir2.h"
 #include "xfs_bmap_btree.h"
 #include "xfs_ialloc_btree.h"
 #include "xfs_dinode.h"
 #include "xfs_inode.h"
 #include "xfs_ialloc.h"
 #include "xfs_alloc.h"
 #include "xfs_bmap.h"
 #include "xfs_bmap_util.h"
 #include "xfs_error.h"
 #include "xfs_quota.h"
 #include "xfs_trans_space.h"
 #include "xfs_trace.h"
 #include "xfs_symlink.h"

 /* ----- Kernel only functions below ----- */
 STATIC int
 xfs_readlink_bmap(
 	struct xfs_inode	*ip,
 	char			*link)
 {
 	struct xfs_mount	*mp = ip->i_mount;
 	struct xfs_bmbt_irec	mval[XFS_SYMLINK_MAPS];
 	struct xfs_buf		*bp;
 	xfs_daddr_t		d;
 	char			*cur_chunk;
 	int			pathlen = ip->i_d.di_size;
 	int			nmaps = XFS_SYMLINK_MAPS;
 	int			byte_cnt;
 	int			n;
 	int			error = 0;
 	int			fsblocks = 0;
 	int			offset;

 	fsblocks = xfs_symlink_blocks(mp, pathlen);
 	error = xfs_bmapi_read(ip, 0, fsblocks, mval, &nmaps, 0);
 	if (error)
 		goto out;

 	offset = 0;
 	for (n = 0; n < nmaps; n++) {
 		d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
 		byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);

 		bp = xfs_buf_read(mp->m_ddev_targp, d, BTOBB(byte_cnt), 0,
 				  &xfs_symlink_buf_ops);
 		if (!bp)
 			return XFS_ERROR(ENOMEM);
 		error = bp->b_error;
 		if (error) {
 			xfs_buf_ioerror_alert(bp, __func__);
 			xfs_buf_relse(bp);
 			goto out;
 		}
 		byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
 		if (pathlen < byte_cnt)
 			byte_cnt = pathlen;

 		cur_chunk = bp->b_addr;
 		if (xfs_sb_version_hascrc(&mp->m_sb)) {
 			if (!xfs_symlink_hdr_ok(mp, ip->i_ino, offset,
 							byte_cnt, bp)) {
 				error = EFSCORRUPTED;
 				xfs_alert(mp,
 "symlink header does not match required off/len/owner (0x%x/Ox%x,0x%llx)",
 					offset, byte_cnt, ip->i_ino);
 				xfs_buf_relse(bp);
 				goto out;

 			}

 			cur_chunk += sizeof(struct xfs_dsymlink_hdr);
 		}

 		memcpy(link + offset, bp->b_addr, byte_cnt);

 		pathlen -= byte_cnt;
 		offset += byte_cnt;

 		xfs_buf_relse(bp);
 	}
 	ASSERT(pathlen == 0);

 	link[ip->i_d.di_size] = '\0';
 	error = 0;

  out:
 	return error;
 }

 int
 xfs_readlink(
 	struct xfs_inode *ip,
 	char		*link)
 {
 	struct xfs_mount *mp = ip->i_mount;
 	xfs_fsize_t	pathlen;
 	int		error = 0;

 	trace_xfs_readlink(ip);

 	if (XFS_FORCED_SHUTDOWN(mp))
 		return XFS_ERROR(EIO);

 	xfs_ilock(ip, XFS_ILOCK_SHARED);

 	pathlen = ip->i_d.di_size;
 	if (!pathlen)
 		goto out;

 	if (pathlen < 0 || pathlen > MAXPATHLEN) {
 		xfs_alert(mp, "%s: inode (%llu) bad symlink length (%lld)",
 			 __func__, (unsigned long long) ip->i_ino,
 			 (long long) pathlen);
 		ASSERT(0);
 		error = XFS_ERROR(EFSCORRUPTED);
 		goto out;
 	}


 	if (ip->i_df.if_flags & XFS_IFINLINE) {
 		memcpy(link, ip->i_df.if_u1.if_data, pathlen);
 		link[pathlen] = '\0';
 	} else {
 		error = xfs_readlink_bmap(ip, link);
 	}

  out:
 	xfs_iunlock(ip, XFS_ILOCK_SHARED);
 	return error;
 }

 int
 xfs_symlink(
 	struct xfs_inode	*dp,
 	struct xfs_name		*link_name,
 	const char		*target_path,
 	umode_t			mode,
 	struct xfs_inode	**ipp)
 {
 	struct xfs_mount	*mp = dp->i_mount;
 	struct xfs_trans	*tp = NULL;
 	struct xfs_inode	*ip = NULL;
 	int			error = 0;
 	int			pathlen;
 	struct xfs_bmap_free	free_list;
 	xfs_fsblock_t		first_block;
 	bool			unlock_dp_on_error = false;
 	uint			cancel_flags;
 	int			committed;
 	xfs_fileoff_t		first_fsb;
 	xfs_filblks_t		fs_blocks;
 	int			nmaps;
 	struct xfs_bmbt_irec	mval[XFS_SYMLINK_MAPS];
 	xfs_daddr_t		d;
 	const char		*cur_chunk;
 	int			byte_cnt;
 	int			n;
 	xfs_buf_t		*bp;
 	prid_t			prid;
 	struct xfs_dquot	*udqp = NULL;
 	struct xfs_dquot	*gdqp = NULL;
 	struct xfs_dquot	*pdqp = NULL;
 	uint			resblks;

 	*ipp = NULL;

 	trace_xfs_symlink(dp, link_name);

 	if (XFS_FORCED_SHUTDOWN(mp))
 		return XFS_ERROR(EIO);

 	/*
 	 * Check component lengths of the target path name.
 	 */
 	pathlen = strlen(target_path);
 	if (pathlen >= MAXPATHLEN)      /* total string too long */
 		return XFS_ERROR(ENAMETOOLONG);

 	udqp = gdqp = NULL;
 	if (dp->i_d.di_flags & XFS_DIFLAG_PROJINHERIT)
 		prid = xfs_get_projid(dp);
 	else
 		prid = XFS_PROJID_DEFAULT;

 	/*
 	 * Make sure that we have allocated dquot(s) on disk.
 	 */
 	error = xfs_qm_vop_dqalloc(dp,
 			xfs_kuid_to_uid(current_fsuid()),
 			xfs_kgid_to_gid(current_fsgid()), prid,
 			XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
 			&udqp, &gdqp, &pdqp);
 	if (error)
 		goto std_return;

 	tp = xfs_trans_alloc(mp, XFS_TRANS_SYMLINK);
 	cancel_flags = XFS_TRANS_RELEASE_LOG_RES;
 	/*
 	 * The symlink will fit into the inode data fork?
 	 * There can't be any attributes so we get the whole variable part.
 	 */
 	if (pathlen <= XFS_LITINO(mp, dp->i_d.di_version))
 		fs_blocks = 0;
 	else
 		fs_blocks = xfs_symlink_blocks(mp, pathlen);
 	resblks = XFS_SYMLINK_SPACE_RES(mp, link_name->len, fs_blocks);
 	error = xfs_trans_reserve(tp, &M_RES(mp)->tr_symlink, resblks, 0);
 	if (error == ENOSPC && fs_blocks == 0) {
 		resblks = 0;
 		error = xfs_trans_reserve(tp, &M_RES(mp)->tr_symlink, 0, 0);
 	}
 	if (error) {
 		cancel_flags = 0;
 		goto error_return;
 	}

 	xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
 	unlock_dp_on_error = true;

 	/*
 	 * Check whether the directory allows new symlinks or not.
 	 */
 	if (dp->i_d.di_flags & XFS_DIFLAG_NOSYMLINKS) {
 		error = XFS_ERROR(EPERM);
 		goto error_return;
 	}

 	/*
 	 * Reserve disk quota : blocks and inode.
 	 */
 	error = xfs_trans_reserve_quota(tp, mp, udqp, gdqp,
 						pdqp, resblks, 1, 0);
 	if (error)
 		goto error_return;

 	/*
 	 * Check for ability to enter directory entry, if no space reserved.
 	 */
 	error = xfs_dir_canenter(tp, dp, link_name, resblks);
 	if (error)
 		goto error_return;
 	/*
 	 * Initialize the bmap freelist prior to calling either
 	 * bmapi or the directory create code.
 	 */
 	xfs_bmap_init(&free_list, &first_block);

 	/*
 	 * Allocate an inode for the symlink.
 	 */
 	error = xfs_dir_ialloc(&tp, dp, S_IFLNK | (mode & ~S_IFMT), 1, 0,
 			       prid, resblks > 0, &ip, NULL);
 	if (error) {
 		if (error == ENOSPC)
 			goto error_return;
 		goto error1;
 	}

 	/*
 	 * An error after we've joined dp to the transaction will result in the
 	 * transaction cancel unlocking dp so don't do it explicitly in the
 	 * error path.
 	 */
 	xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
 	unlock_dp_on_error = false;

 	/*
 	 * Also attach the dquot(s) to it, if applicable.
 	 */
 	xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp);

 	if (resblks)
 		resblks -= XFS_IALLOC_SPACE_RES(mp);
 	/*
 	 * If the symlink will fit into the inode, write it inline.
 	 */
 	if (pathlen <= XFS_IFORK_DSIZE(ip)) {
 		xfs_idata_realloc(ip, pathlen, XFS_DATA_FORK);
 		memcpy(ip->i_df.if_u1.if_data, target_path, pathlen);
 		ip->i_d.di_size = pathlen;

 		/*
 		 * The inode was initially created in extent format.
 		 */
 		ip->i_df.if_flags &= ~(XFS_IFEXTENTS | XFS_IFBROOT);
 		ip->i_df.if_flags |= XFS_IFINLINE;

 		ip->i_d.di_format = XFS_DINODE_FMT_LOCAL;
 		xfs_trans_log_inode(tp, ip, XFS_ILOG_DDATA | XFS_ILOG_CORE);

 	} else {
 		int	offset;

 		first_fsb = 0;
 		nmaps = XFS_SYMLINK_MAPS;

 		error = xfs_bmapi_write(tp, ip, first_fsb, fs_blocks,
 				  XFS_BMAPI_METADATA, &first_block, resblks,
 				  mval, &nmaps, &free_list);
 		if (error)
 			goto error2;

 		if (resblks)
 			resblks -= fs_blocks;
 		ip->i_d.di_size = pathlen;
 		xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);

 		cur_chunk = target_path;
 		offset = 0;
 		for (n = 0; n < nmaps; n++) {
 			char	*buf;

 			d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
 			byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
 			bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, d,
 					       BTOBB(byte_cnt), 0);
 			if (!bp) {
 				error = ENOMEM;
 				goto error2;
 			}
 			bp->b_ops = &xfs_symlink_buf_ops;

 			byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
 			byte_cnt = min(byte_cnt, pathlen);

 			buf = bp->b_addr;
 			buf += xfs_symlink_hdr_set(mp, ip->i_ino, offset,
 						   byte_cnt, bp);

 			memcpy(buf, cur_chunk, byte_cnt);

 			cur_chunk += byte_cnt;
 			pathlen -= byte_cnt;
 			offset += byte_cnt;

 			xfs_trans_log_buf(tp, bp, 0, (buf + byte_cnt - 1) -
 							(char *)bp->b_addr);
 		}
 		ASSERT(pathlen == 0);
 	}

 	/*
 	 * Create the directory entry for the symlink.
 	 */
 	error = xfs_dir_createname(tp, dp, link_name, ip->i_ino,
 					&first_block, &free_list, resblks);
 	if (error)
 		goto error2;
 	xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
 	xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);

 	/*
 	 * If this is a synchronous mount, make sure that the
 	 * symlink transaction goes to disk before returning to
 	 * the user.
 	 */
 	if (mp->m_flags & (XFS_MOUNT_WSYNC|XFS_MOUNT_DIRSYNC)) {
 		xfs_trans_set_sync(tp);
 	}

 	error = xfs_bmap_finish(&tp, &free_list, &committed);
 	if (error) {
 		goto error2;
 	}
 	error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 	xfs_qm_dqrele(udqp);
 	xfs_qm_dqrele(gdqp);
 	xfs_qm_dqrele(pdqp);

 	*ipp = ip;
 	return 0;

  error2:
 	IRELE(ip);
  error1:
 	xfs_bmap_cancel(&free_list);
 	cancel_flags |= XFS_TRANS_ABORT;
  error_return:
 	xfs_trans_cancel(tp, cancel_flags);
 	xfs_qm_dqrele(udqp);
 	xfs_qm_dqrele(gdqp);
 	xfs_qm_dqrele(pdqp);

 	if (unlock_dp_on_error)
 		xfs_iunlock(dp, XFS_ILOCK_EXCL);
  std_return:
 	return error;
 }

 /*
  * Free a symlink that has blocks associated with it.
  */
 STATIC int
 xfs_inactive_symlink_rmt(
 	xfs_inode_t	*ip,
 	xfs_trans_t	**tpp)
 {
 	xfs_buf_t	*bp;
 	int		committed;
 	int		done;
 	int		error;
 	xfs_fsblock_t	first_block;
 	xfs_bmap_free_t	free_list;
 	int		i;
 	xfs_mount_t	*mp;
 	xfs_bmbt_irec_t	mval[XFS_SYMLINK_MAPS];
 	int		nmaps;
 	xfs_trans_t	*ntp;
 	int		size;
 	xfs_trans_t	*tp;

 	tp = *tpp;
 	mp = ip->i_mount;
 	ASSERT(ip->i_df.if_flags & XFS_IFEXTENTS);
 	/*
 	 * We're freeing a symlink that has some
 	 * blocks allocated to it.  Free the
 	 * blocks here.  We know that we've got
 	 * either 1 or 2 extents and that we can
 	 * free them all in one bunmapi call.
 	 */
 	ASSERT(ip->i_d.di_nextents > 0 && ip->i_d.di_nextents <= 2);

 	/*
 	 * Lock the inode, fix the size, and join it to the transaction.
 	 * Hold it so in the normal path, we still have it locked for
 	 * the second transaction.  In the error paths we need it
 	 * held so the cancel won't rele it, see below.
 	 */
 	size = (int)ip->i_d.di_size;
 	ip->i_d.di_size = 0;
 	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 	/*
 	 * Find the block(s) so we can inval and unmap them.
 	 */
 	done = 0;
 	xfs_bmap_init(&free_list, &first_block);
 	nmaps = ARRAY_SIZE(mval);
 	error = xfs_bmapi_read(ip, 0, xfs_symlink_blocks(mp, size),
 				mval, &nmaps, 0);
 	if (error)
 		goto error0;
 	/*
 	 * Invalidate the block(s). No validation is done.
 	 */
 	for (i = 0; i < nmaps; i++) {
 		bp = xfs_trans_get_buf(tp, mp->m_ddev_targp,
 			XFS_FSB_TO_DADDR(mp, mval[i].br_startblock),
 			XFS_FSB_TO_BB(mp, mval[i].br_blockcount), 0);
 		if (!bp) {
 			error = ENOMEM;
 			goto error1;
 		}
 		xfs_trans_binval(tp, bp);
 	}
 	/*
 	 * Unmap the dead block(s) to the free_list.
 	 */
 	if ((error = xfs_bunmapi(tp, ip, 0, size, XFS_BMAPI_METADATA, nmaps,
 			&first_block, &free_list, &done)))
 		goto error1;
 	ASSERT(done);
 	/*
 	 * Commit the first transaction.  This logs the EFI and the inode.
 	 */
 	if ((error = xfs_bmap_finish(&tp, &free_list, &committed)))
 		goto error1;
 	/*
 	 * The transaction must have been committed, since there were
 	 * actually extents freed by xfs_bunmapi.  See xfs_bmap_finish.
 	 * The new tp has the extent freeing and EFDs.
 	 */
 	ASSERT(committed);
 	/*
 	 * The first xact was committed, so add the inode to the new one.
 	 * Mark it dirty so it will be logged and moved forward in the log as
 	 * part of every commit.
 	 */
 	xfs_trans_ijoin(tp, ip, 0);
 	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 	/*
 	 * Get a new, empty transaction to return to our caller.
 	 */
 	ntp = xfs_trans_dup(tp);
 	/*
 	 * Commit the transaction containing extent freeing and EFDs.
 	 * If we get an error on the commit here or on the reserve below,
 	 * we need to unlock the inode since the new transaction doesn't
 	 * have the inode attached.
 	 */
 	error = xfs_trans_commit(tp, 0);
 	tp = ntp;
 	if (error) {
 		ASSERT(XFS_FORCED_SHUTDOWN(mp));
 		goto error0;
 	}
 	/*
 	 * transaction commit worked ok so we can drop the extra ticket
 	 * reference that we gained in xfs_trans_dup()
 	 */
 	xfs_log_ticket_put(tp->t_ticket);

 	/*
 	 * Remove the memory for extent descriptions (just bookkeeping).
 	 */
 	if (ip->i_df.if_bytes)
 		xfs_idata_realloc(ip, -ip->i_df.if_bytes, XFS_DATA_FORK);
 	ASSERT(ip->i_df.if_bytes == 0);
 	/*
 	 * Put an itruncate log reservation in the new transaction
 	 * for our caller.
 	 */
 	error = xfs_trans_reserve(tp, &M_RES(mp)->tr_itruncate, 0, 0);
 	if (error) {
 		ASSERT(XFS_FORCED_SHUTDOWN(mp));
 		goto error0;
 	}

 	xfs_trans_ijoin(tp, ip, 0);
 	*tpp = tp;
 	return 0;

  error1:
 	xfs_bmap_cancel(&free_list);
  error0:
 	return error;
 }

 /*
  * xfs_inactive_symlink - free a symlink
  */
 int
 xfs_inactive_symlink(
 	struct xfs_inode	*ip,
 	struct xfs_trans	**tp)
 {
 	struct xfs_mount	*mp = ip->i_mount;
 	int			pathlen;

 	trace_xfs_inactive_symlink(ip);

 	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));

 	if (XFS_FORCED_SHUTDOWN(mp))
 		return XFS_ERROR(EIO);

 	/*
 	 * Zero length symlinks _can_ exist.
 	 */
 	pathlen = (int)ip->i_d.di_size;
 	if (!pathlen)
 		return 0;

 	if (pathlen < 0 || pathlen > MAXPATHLEN) {
 		xfs_alert(mp, "%s: inode (0x%llx) bad symlink length (%d)",
 			 __func__, (unsigned long long)ip->i_ino, pathlen);
 		ASSERT(0);
 		return XFS_ERROR(EFSCORRUPTED);
 	}

 	if (ip->i_df.if_flags & XFS_IFINLINE) {
 		if (ip->i_df.if_bytes > 0)
 			xfs_idata_realloc(ip, -(ip->i_df.if_bytes),
 					  XFS_DATA_FORK);
 		ASSERT(ip->i_df.if_bytes == 0);
 		return 0;
 	}

 	/* remove the remote symlink */
 	return xfs_inactive_symlink_rmt(ip, tp);
 }
	/*
	* Copyright (c) 2000-2006 Silicon Graphics, Inc.
	* Copyright (c) 2012-2013 Red Hat, 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_format.h"
	#include "xfs_bit.h"
	#include "xfs_log.h"
	#include "xfs_trans.h"
	#include "xfs_sb.h"
	#include "xfs_ag.h"
	#include "xfs_mount.h"
	#include "xfs_da_btree.h"
	#include "xfs_dir2_format.h"
	#include "xfs_dir2.h"
	#include "xfs_bmap_btree.h"
	#include "xfs_ialloc_btree.h"
	#include "xfs_dinode.h"
	#include "xfs_inode.h"
	#include "xfs_ialloc.h"
	#include "xfs_alloc.h"
	#include "xfs_bmap.h"
	#include "xfs_bmap_util.h"
	#include "xfs_error.h"
	#include "xfs_quota.h"
	#include "xfs_trans_space.h"
	#include "xfs_trace.h"
	#include "xfs_symlink.h"

	/* ----- Kernel only functions below ----- */
	STATIC int
	xfs_readlink_bmap(
	struct xfs_inode *ip,
	char *link)
	{
	struct xfs_mount *mp = ip->i_mount;
	struct xfs_bmbt_irec mval[XFS_SYMLINK_MAPS];
	struct xfs_buf *bp;
	xfs_daddr_t d;
	char *cur_chunk;
	int pathlen = ip->i_d.di_size;
	int nmaps = XFS_SYMLINK_MAPS;
	int byte_cnt;
	int n;
	int error = 0;
	int fsblocks = 0;
	int offset;

	fsblocks = xfs_symlink_blocks(mp, pathlen);
	error = xfs_bmapi_read(ip, 0, fsblocks, mval, &nmaps, 0);
	if (error)
	goto out;

	offset = 0;
	for (n = 0; n < nmaps; n++) {
	d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
	byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);

	bp = xfs_buf_read(mp->m_ddev_targp, d, BTOBB(byte_cnt), 0,
	&xfs_symlink_buf_ops);
	if (!bp)
	return XFS_ERROR(ENOMEM);
	error = bp->b_error;
	if (error) {
	xfs_buf_ioerror_alert(bp, __func__);
	xfs_buf_relse(bp);
	goto out;
	}
	byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
	if (pathlen < byte_cnt)
	byte_cnt = pathlen;

	cur_chunk = bp->b_addr;
	if (xfs_sb_version_hascrc(&mp->m_sb)) {
	if (!xfs_symlink_hdr_ok(mp, ip->i_ino, offset,
	byte_cnt, bp)) {
	error = EFSCORRUPTED;
	xfs_alert(mp,
	"symlink header does not match required off/len/owner (0x%x/Ox%x,0x%llx)",
	offset, byte_cnt, ip->i_ino);
	xfs_buf_relse(bp);
	goto out;

	}

	cur_chunk += sizeof(struct xfs_dsymlink_hdr);
	}

	memcpy(link + offset, bp->b_addr, byte_cnt);

	pathlen -= byte_cnt;
	offset += byte_cnt;

	xfs_buf_relse(bp);
	}
	ASSERT(pathlen == 0);

	link[ip->i_d.di_size] = '\0';
	error = 0;

	out:
	return error;
	}

	int
	xfs_readlink(
	struct xfs_inode *ip,
	char *link)
	{
	struct xfs_mount *mp = ip->i_mount;
	xfs_fsize_t pathlen;
	int error = 0;

	trace_xfs_readlink(ip);

	if (XFS_FORCED_SHUTDOWN(mp))
	return XFS_ERROR(EIO);

	xfs_ilock(ip, XFS_ILOCK_SHARED);

	pathlen = ip->i_d.di_size;
	if (!pathlen)
	goto out;

	if (pathlen < 0 \|\| pathlen > MAXPATHLEN) {
	xfs_alert(mp, "%s: inode (%llu) bad symlink length (%lld)",
	__func__, (unsigned long long) ip->i_ino,
	(long long) pathlen);
	ASSERT(0);
	error = XFS_ERROR(EFSCORRUPTED);
	goto out;
	}


	if (ip->i_df.if_flags & XFS_IFINLINE) {
	memcpy(link, ip->i_df.if_u1.if_data, pathlen);
	link[pathlen] = '\0';
	} else {
	error = xfs_readlink_bmap(ip, link);
	}

	out:
	xfs_iunlock(ip, XFS_ILOCK_SHARED);
	return error;
	}

	int
	xfs_symlink(
	struct xfs_inode *dp,
	struct xfs_name *link_name,
	const char *target_path,
	umode_t mode,
	struct xfs_inode **ipp)
	{
	struct xfs_mount *mp = dp->i_mount;
	struct xfs_trans *tp = NULL;
	struct xfs_inode *ip = NULL;
	int error = 0;
	int pathlen;
	struct xfs_bmap_free free_list;
	xfs_fsblock_t first_block;
	bool unlock_dp_on_error = false;
	uint cancel_flags;
	int committed;
	xfs_fileoff_t first_fsb;
	xfs_filblks_t fs_blocks;
	int nmaps;
	struct xfs_bmbt_irec mval[XFS_SYMLINK_MAPS];
	xfs_daddr_t d;
	const char *cur_chunk;
	int byte_cnt;
	int n;
	xfs_buf_t *bp;
	prid_t prid;
	struct xfs_dquot *udqp = NULL;
	struct xfs_dquot *gdqp = NULL;
	struct xfs_dquot *pdqp = NULL;
	uint resblks;

	*ipp = NULL;

	trace_xfs_symlink(dp, link_name);

	if (XFS_FORCED_SHUTDOWN(mp))
	return XFS_ERROR(EIO);

	/*
	* Check component lengths of the target path name.
	*/
	pathlen = strlen(target_path);
	if (pathlen >= MAXPATHLEN) /* total string too long */
	return XFS_ERROR(ENAMETOOLONG);

	udqp = gdqp = NULL;
	if (dp->i_d.di_flags & XFS_DIFLAG_PROJINHERIT)
	prid = xfs_get_projid(dp);
	else
	prid = XFS_PROJID_DEFAULT;

	/*
	* Make sure that we have allocated dquot(s) on disk.
	*/
	error = xfs_qm_vop_dqalloc(dp,
	xfs_kuid_to_uid(current_fsuid()),
	xfs_kgid_to_gid(current_fsgid()), prid,
	XFS_QMOPT_QUOTALL \| XFS_QMOPT_INHERIT,
	&udqp, &gdqp, &pdqp);
	if (error)
	goto std_return;

	tp = xfs_trans_alloc(mp, XFS_TRANS_SYMLINK);
	cancel_flags = XFS_TRANS_RELEASE_LOG_RES;
	/*
	* The symlink will fit into the inode data fork?
	* There can't be any attributes so we get the whole variable part.
	*/
	if (pathlen <= XFS_LITINO(mp, dp->i_d.di_version))
	fs_blocks = 0;
	else
	fs_blocks = xfs_symlink_blocks(mp, pathlen);
	resblks = XFS_SYMLINK_SPACE_RES(mp, link_name->len, fs_blocks);
	error = xfs_trans_reserve(tp, &M_RES(mp)->tr_symlink, resblks, 0);
	if (error == ENOSPC && fs_blocks == 0) {
	resblks = 0;
	error = xfs_trans_reserve(tp, &M_RES(mp)->tr_symlink, 0, 0);
	}
	if (error) {
	cancel_flags = 0;
	goto error_return;
	}

	xfs_ilock(dp, XFS_ILOCK_EXCL \| XFS_ILOCK_PARENT);
	unlock_dp_on_error = true;

	/*
	* Check whether the directory allows new symlinks or not.
	*/
	if (dp->i_d.di_flags & XFS_DIFLAG_NOSYMLINKS) {
	error = XFS_ERROR(EPERM);
	goto error_return;
	}

	/*
	* Reserve disk quota : blocks and inode.
	*/
	error = xfs_trans_reserve_quota(tp, mp, udqp, gdqp,
	pdqp, resblks, 1, 0);
	if (error)
	goto error_return;

	/*
	* Check for ability to enter directory entry, if no space reserved.
	*/
	error = xfs_dir_canenter(tp, dp, link_name, resblks);
	if (error)
	goto error_return;
	/*
	* Initialize the bmap freelist prior to calling either
	* bmapi or the directory create code.
	*/
	xfs_bmap_init(&free_list, &first_block);

	/*
	* Allocate an inode for the symlink.
	*/
	error = xfs_dir_ialloc(&tp, dp, S_IFLNK \| (mode & ~S_IFMT), 1, 0,
	prid, resblks > 0, &ip, NULL);
	if (error) {
	if (error == ENOSPC)
	goto error_return;
	goto error1;
	}

	/*
	* An error after we've joined dp to the transaction will result in the
	* transaction cancel unlocking dp so don't do it explicitly in the
	* error path.
	*/
	xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
	unlock_dp_on_error = false;

	/*
	* Also attach the dquot(s) to it, if applicable.
	*/
	xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp);

	if (resblks)
	resblks -= XFS_IALLOC_SPACE_RES(mp);
	/*
	* If the symlink will fit into the inode, write it inline.
	*/
	if (pathlen <= XFS_IFORK_DSIZE(ip)) {
	xfs_idata_realloc(ip, pathlen, XFS_DATA_FORK);
	memcpy(ip->i_df.if_u1.if_data, target_path, pathlen);
	ip->i_d.di_size = pathlen;

	/*
	* The inode was initially created in extent format.
	*/
	ip->i_df.if_flags &= ~(XFS_IFEXTENTS \| XFS_IFBROOT);
	ip->i_df.if_flags \|= XFS_IFINLINE;

	ip->i_d.di_format = XFS_DINODE_FMT_LOCAL;
	xfs_trans_log_inode(tp, ip, XFS_ILOG_DDATA \| XFS_ILOG_CORE);

	} else {
	int offset;

	first_fsb = 0;
	nmaps = XFS_SYMLINK_MAPS;

	error = xfs_bmapi_write(tp, ip, first_fsb, fs_blocks,
	XFS_BMAPI_METADATA, &first_block, resblks,
	mval, &nmaps, &free_list);
	if (error)
	goto error2;

	if (resblks)
	resblks -= fs_blocks;
	ip->i_d.di_size = pathlen;
	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);

	cur_chunk = target_path;
	offset = 0;
	for (n = 0; n < nmaps; n++) {
	char *buf;

	d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
	byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
	bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, d,
	BTOBB(byte_cnt), 0);
	if (!bp) {
	error = ENOMEM;
	goto error2;
	}
	bp->b_ops = &xfs_symlink_buf_ops;

	byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
	byte_cnt = min(byte_cnt, pathlen);

	buf = bp->b_addr;
	buf += xfs_symlink_hdr_set(mp, ip->i_ino, offset,
	byte_cnt, bp);

	memcpy(buf, cur_chunk, byte_cnt);

	cur_chunk += byte_cnt;
	pathlen -= byte_cnt;
	offset += byte_cnt;

	xfs_trans_log_buf(tp, bp, 0, (buf + byte_cnt - 1) -
	(char *)bp->b_addr);
	}
	ASSERT(pathlen == 0);
	}

	/*
	* Create the directory entry for the symlink.
	*/
	error = xfs_dir_createname(tp, dp, link_name, ip->i_ino,
	&first_block, &free_list, resblks);
	if (error)
	goto error2;
	xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD \| XFS_ICHGTIME_CHG);
	xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);

	/*
	* If this is a synchronous mount, make sure that the
	* symlink transaction goes to disk before returning to
	* the user.
	*/
	if (mp->m_flags & (XFS_MOUNT_WSYNC\|XFS_MOUNT_DIRSYNC)) {
	xfs_trans_set_sync(tp);
	}

	error = xfs_bmap_finish(&tp, &free_list, &committed);
	if (error) {
	goto error2;
	}
	error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
	xfs_qm_dqrele(udqp);
	xfs_qm_dqrele(gdqp);
	xfs_qm_dqrele(pdqp);

	*ipp = ip;
	return 0;

	error2:
	IRELE(ip);
	error1:
	xfs_bmap_cancel(&free_list);
	cancel_flags \|= XFS_TRANS_ABORT;
	error_return:
	xfs_trans_cancel(tp, cancel_flags);
	xfs_qm_dqrele(udqp);
	xfs_qm_dqrele(gdqp);
	xfs_qm_dqrele(pdqp);

	if (unlock_dp_on_error)
	xfs_iunlock(dp, XFS_ILOCK_EXCL);
	std_return:
	return error;
	}

	/*
	* Free a symlink that has blocks associated with it.
	*/
	STATIC int
	xfs_inactive_symlink_rmt(
	xfs_inode_t *ip,
	xfs_trans_t **tpp)
	{
	xfs_buf_t *bp;
	int committed;
	int done;
	int error;
	xfs_fsblock_t first_block;
	xfs_bmap_free_t free_list;
	int i;
	xfs_mount_t *mp;
	xfs_bmbt_irec_t mval[XFS_SYMLINK_MAPS];
	int nmaps;
	xfs_trans_t *ntp;
	int size;
	xfs_trans_t *tp;

	tp = *tpp;
	mp = ip->i_mount;
	ASSERT(ip->i_df.if_flags & XFS_IFEXTENTS);
	/*
	* We're freeing a symlink that has some
	* blocks allocated to it. Free the
	* blocks here. We know that we've got
	* either 1 or 2 extents and that we can
	* free them all in one bunmapi call.
	*/
	ASSERT(ip->i_d.di_nextents > 0 && ip->i_d.di_nextents <= 2);

	/*
	* Lock the inode, fix the size, and join it to the transaction.
	* Hold it so in the normal path, we still have it locked for
	* the second transaction. In the error paths we need it
	* held so the cancel won't rele it, see below.
	*/
	size = (int)ip->i_d.di_size;
	ip->i_d.di_size = 0;
	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
	/*
	* Find the block(s) so we can inval and unmap them.
	*/
	done = 0;
	xfs_bmap_init(&free_list, &first_block);
	nmaps = ARRAY_SIZE(mval);
	error = xfs_bmapi_read(ip, 0, xfs_symlink_blocks(mp, size),
	mval, &nmaps, 0);
	if (error)
	goto error0;
	/*
	* Invalidate the block(s). No validation is done.
	*/
	for (i = 0; i < nmaps; i++) {
	bp = xfs_trans_get_buf(tp, mp->m_ddev_targp,
	XFS_FSB_TO_DADDR(mp, mval[i].br_startblock),
	XFS_FSB_TO_BB(mp, mval[i].br_blockcount), 0);
	if (!bp) {
	error = ENOMEM;
	goto error1;
	}
	xfs_trans_binval(tp, bp);
	}
	/*
	* Unmap the dead block(s) to the free_list.
	*/
	if ((error = xfs_bunmapi(tp, ip, 0, size, XFS_BMAPI_METADATA, nmaps,
	&first_block, &free_list, &done)))
	goto error1;
	ASSERT(done);
	/*
	* Commit the first transaction. This logs the EFI and the inode.
	*/
	if ((error = xfs_bmap_finish(&tp, &free_list, &committed)))
	goto error1;
	/*
	* The transaction must have been committed, since there were
	* actually extents freed by xfs_bunmapi. See xfs_bmap_finish.
	* The new tp has the extent freeing and EFDs.
	*/
	ASSERT(committed);
	/*
	* The first xact was committed, so add the inode to the new one.
	* Mark it dirty so it will be logged and moved forward in the log as
	* part of every commit.
	*/
	xfs_trans_ijoin(tp, ip, 0);
	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
	/*
	* Get a new, empty transaction to return to our caller.
	*/
	ntp = xfs_trans_dup(tp);
	/*
	* Commit the transaction containing extent freeing and EFDs.
	* If we get an error on the commit here or on the reserve below,
	* we need to unlock the inode since the new transaction doesn't
	* have the inode attached.
	*/
	error = xfs_trans_commit(tp, 0);
	tp = ntp;
	if (error) {
	ASSERT(XFS_FORCED_SHUTDOWN(mp));
	goto error0;
	}
	/*
	* transaction commit worked ok so we can drop the extra ticket
	* reference that we gained in xfs_trans_dup()
	*/
	xfs_log_ticket_put(tp->t_ticket);

	/*
	* Remove the memory for extent descriptions (just bookkeeping).
	*/
	if (ip->i_df.if_bytes)
	xfs_idata_realloc(ip, -ip->i_df.if_bytes, XFS_DATA_FORK);
	ASSERT(ip->i_df.if_bytes == 0);
	/*
	* Put an itruncate log reservation in the new transaction
	* for our caller.
	*/
	error = xfs_trans_reserve(tp, &M_RES(mp)->tr_itruncate, 0, 0);
	if (error) {
	ASSERT(XFS_FORCED_SHUTDOWN(mp));
	goto error0;
	}

	xfs_trans_ijoin(tp, ip, 0);
	*tpp = tp;
	return 0;

	error1:
	xfs_bmap_cancel(&free_list);
	error0:
	return error;
	}

	/*
	* xfs_inactive_symlink - free a symlink
	*/
	int
	xfs_inactive_symlink(
	struct xfs_inode *ip,
	struct xfs_trans **tp)
	{
	struct xfs_mount *mp = ip->i_mount;
	int pathlen;

	trace_xfs_inactive_symlink(ip);

	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));

	if (XFS_FORCED_SHUTDOWN(mp))
	return XFS_ERROR(EIO);

	/*
	* Zero length symlinks _can_ exist.
	*/
	pathlen = (int)ip->i_d.di_size;
	if (!pathlen)
	return 0;

	if (pathlen < 0 \|\| pathlen > MAXPATHLEN) {
	xfs_alert(mp, "%s: inode (0x%llx) bad symlink length (%d)",
	__func__, (unsigned long long)ip->i_ino, pathlen);
	ASSERT(0);
	return XFS_ERROR(EFSCORRUPTED);
	}

	if (ip->i_df.if_flags & XFS_IFINLINE) {
	if (ip->i_df.if_bytes > 0)
	xfs_idata_realloc(ip, -(ip->i_df.if_bytes),
	XFS_DATA_FORK);
	ASSERT(ip->i_df.if_bytes == 0);
	return 0;
	}

	/* remove the remote symlink */
	return xfs_inactive_symlink_rmt(ip, tp);
	}