fs/xfs/libxfs/xfs_inode_fork.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (c) 2000-2006 Silicon Graphics, Inc.
  * All Rights Reserved.
  */

 #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_inode.h"
 #include "xfs_trans.h"
 #include "xfs_inode_item.h"
 #include "xfs_btree.h"
 #include "xfs_bmap_btree.h"
 #include "xfs_bmap.h"
 #include "xfs_error.h"
 #include "xfs_trace.h"
 #include "xfs_da_format.h"
 #include "xfs_da_btree.h"
 #include "xfs_dir2_priv.h"
 #include "xfs_attr_leaf.h"
 #include "xfs_types.h"
 #include "xfs_errortag.h"
 #include "xfs_health.h"
 #include "xfs_symlink_remote.h"

 struct kmem_cache *xfs_ifork_cache;

 void
 xfs_init_local_fork(
 	struct xfs_inode	*ip,
 	int			whichfork,
 	const void		*data,
 	int64_t			size)
 {
 	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
 	int			mem_size = size;
 	bool			zero_terminate;

 	/*
 	 * If we are using the local fork to store a symlink body we need to
 	 * zero-terminate it so that we can pass it back to the VFS directly.
 	 * Overallocate the in-memory fork by one for that and add a zero
 	 * to terminate it below.
 	 */
 	zero_terminate = S_ISLNK(VFS_I(ip)->i_mode);
 	if (zero_terminate)
 		mem_size++;

 	if (size) {
 		char *new_data = kmalloc(mem_size,
 				GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);

 		memcpy(new_data, data, size);
 		if (zero_terminate)
 			new_data[size] = '\0';

 		ifp->if_data = new_data;
 	} else {
 		ifp->if_data = NULL;
 	}

 	ifp->if_bytes = size;
 }

 /*
  * The file is in-lined in the on-disk inode.
  */
 STATIC int
 xfs_iformat_local(
 	struct xfs_inode	*ip,
 	struct xfs_dinode	*dip,
 	int			whichfork,
 	int			size)
 {
 	/*
 	 * If the size is unreasonable, then something
 	 * is wrong and we just bail out rather than crash in
 	 * kmalloc() or memcpy() below.
 	 */
 	if (unlikely(size > XFS_DFORK_SIZE(dip, ip->i_mount, whichfork))) {
 		xfs_warn(ip->i_mount,
 	"corrupt inode %llu (bad size %d for local fork, size = %zd).",
 			(unsigned long long) ip->i_ino, size,
 			XFS_DFORK_SIZE(dip, ip->i_mount, whichfork));
 		xfs_inode_verifier_error(ip, -EFSCORRUPTED,
 				"xfs_iformat_local", dip, sizeof(*dip),
 				__this_address);
 		xfs_inode_mark_sick(ip, XFS_SICK_INO_CORE);
 		return -EFSCORRUPTED;
 	}

 	xfs_init_local_fork(ip, whichfork, XFS_DFORK_PTR(dip, whichfork), size);
 	return 0;
 }

 /*
  * The file consists of a set of extents all of which fit into the on-disk
  * inode.
  */
 STATIC int
 xfs_iformat_extents(
 	struct xfs_inode	*ip,
 	struct xfs_dinode	*dip,
 	int			whichfork)
 {
 	struct xfs_mount	*mp = ip->i_mount;
 	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
 	int			state = xfs_bmap_fork_to_state(whichfork);
 	xfs_extnum_t		nex = xfs_dfork_nextents(dip, whichfork);
 	int			size = nex * sizeof(xfs_bmbt_rec_t);
 	struct xfs_iext_cursor	icur;
 	struct xfs_bmbt_rec	*dp;
 	struct xfs_bmbt_irec	new;
 	int			i;

 	/*
 	 * If the number of extents is unreasonable, then something is wrong and
 	 * we just bail out rather than crash in kmalloc() or memcpy() below.
 	 */
 	if (unlikely(size < 0 || size > XFS_DFORK_SIZE(dip, mp, whichfork))) {
 		xfs_warn(ip->i_mount, "corrupt inode %llu ((a)extents = %llu).",
 			ip->i_ino, nex);
 		xfs_inode_verifier_error(ip, -EFSCORRUPTED,
 				"xfs_iformat_extents(1)", dip, sizeof(*dip),
 				__this_address);
 		xfs_inode_mark_sick(ip, XFS_SICK_INO_CORE);
 		return -EFSCORRUPTED;
 	}

 	ifp->if_bytes = 0;
 	ifp->if_data = NULL;
 	ifp->if_height = 0;
 	if (size) {
 		dp = (xfs_bmbt_rec_t *) XFS_DFORK_PTR(dip, whichfork);

 		xfs_iext_first(ifp, &icur);
 		for (i = 0; i < nex; i++, dp++) {
 			xfs_failaddr_t	fa;

 			xfs_bmbt_disk_get_all(dp, &new);
 			fa = xfs_bmap_validate_extent(ip, whichfork, &new);
 			if (fa) {
 				xfs_inode_verifier_error(ip, -EFSCORRUPTED,
 						"xfs_iformat_extents(2)",
 						dp, sizeof(*dp), fa);
 				xfs_inode_mark_sick(ip, XFS_SICK_INO_CORE);
 				return xfs_bmap_complain_bad_rec(ip, whichfork,
 						fa, &new);
 			}

 			xfs_iext_insert(ip, &icur, &new, state);
 			trace_xfs_read_extent(ip, &icur, state, _THIS_IP_);
 			xfs_iext_next(ifp, &icur);
 		}
 	}
 	return 0;
 }

 /*
  * The file has too many extents to fit into
  * the inode, so they are in B-tree format.
  * Allocate a buffer for the root of the B-tree
  * and copy the root into it.  The i_extents
  * field will remain NULL until all of the
  * extents are read in (when they are needed).
  */
 STATIC int
 xfs_iformat_btree(
 	struct xfs_inode	*ip,
 	struct xfs_dinode	*dip,
 	int			whichfork)
 {
 	struct xfs_mount	*mp = ip->i_mount;
 	xfs_bmdr_block_t	*dfp;
 	struct xfs_ifork	*ifp;
 	/* REFERENCED */
 	int			nrecs;
 	int			size;
 	int			level;

 	ifp = xfs_ifork_ptr(ip, whichfork);
 	dfp = (xfs_bmdr_block_t *)XFS_DFORK_PTR(dip, whichfork);
 	size = XFS_BMAP_BROOT_SPACE(mp, dfp);
 	nrecs = be16_to_cpu(dfp->bb_numrecs);
 	level = be16_to_cpu(dfp->bb_level);

 	/*
 	 * blow out if -- fork has less extents than can fit in
 	 * fork (fork shouldn't be a btree format), root btree
 	 * block has more records than can fit into the fork,
 	 * or the number of extents is greater than the number of
 	 * blocks.
 	 */
 	if (unlikely(ifp->if_nextents <= XFS_IFORK_MAXEXT(ip, whichfork) ||
 		     nrecs == 0 ||
 		     XFS_BMDR_SPACE_CALC(nrecs) >
 					XFS_DFORK_SIZE(dip, mp, whichfork) ||
 		     ifp->if_nextents > ip->i_nblocks) ||
 		     level == 0 || level > XFS_BM_MAXLEVELS(mp, whichfork)) {
 		xfs_warn(mp, "corrupt inode %llu (btree).",
 					(unsigned long long) ip->i_ino);
 		xfs_inode_verifier_error(ip, -EFSCORRUPTED,
 				"xfs_iformat_btree", dfp, size,
 				__this_address);
 		xfs_inode_mark_sick(ip, XFS_SICK_INO_CORE);
 		return -EFSCORRUPTED;
 	}

 	ifp->if_broot_bytes = size;
 	ifp->if_broot = kmalloc(size,
 				GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);
 	ASSERT(ifp->if_broot != NULL);
 	/*
 	 * Copy and convert from the on-disk structure
 	 * to the in-memory structure.
 	 */
 	xfs_bmdr_to_bmbt(ip, dfp, XFS_DFORK_SIZE(dip, ip->i_mount, whichfork),
 			 ifp->if_broot, size);

 	ifp->if_bytes = 0;
 	ifp->if_data = NULL;
 	ifp->if_height = 0;
 	return 0;
 }

 int
 xfs_iformat_data_fork(
 	struct xfs_inode	*ip,
 	struct xfs_dinode	*dip)
 {
 	struct inode		*inode = VFS_I(ip);
 	int			error;

 	/*
 	 * Initialize the extent count early, as the per-format routines may
 	 * depend on it.  Use release semantics to set needextents /after/ we
 	 * set the format. This ensures that we can use acquire semantics on
 	 * needextents in xfs_need_iread_extents() and be guaranteed to see a
 	 * valid format value after that load.
 	 */
 	ip->i_df.if_format = dip->di_format;
 	ip->i_df.if_nextents = xfs_dfork_data_extents(dip);
 	smp_store_release(&ip->i_df.if_needextents,
 			   ip->i_df.if_format == XFS_DINODE_FMT_BTREE ? 1 : 0);

 	switch (inode->i_mode & S_IFMT) {
 	case S_IFIFO:
 	case S_IFCHR:
 	case S_IFBLK:
 	case S_IFSOCK:
 		ip->i_disk_size = 0;
 		inode->i_rdev = xfs_to_linux_dev_t(xfs_dinode_get_rdev(dip));
 		return 0;
 	case S_IFREG:
 	case S_IFLNK:
 	case S_IFDIR:
 		switch (ip->i_df.if_format) {
 		case XFS_DINODE_FMT_LOCAL:
 			error = xfs_iformat_local(ip, dip, XFS_DATA_FORK,
 					be64_to_cpu(dip->di_size));
 			if (!error)
 				error = xfs_ifork_verify_local_data(ip);
 			return error;
 		case XFS_DINODE_FMT_EXTENTS:
 			return xfs_iformat_extents(ip, dip, XFS_DATA_FORK);
 		case XFS_DINODE_FMT_BTREE:
 			return xfs_iformat_btree(ip, dip, XFS_DATA_FORK);
 		default:
 			xfs_inode_verifier_error(ip, -EFSCORRUPTED, __func__,
 					dip, sizeof(*dip), __this_address);
 			xfs_inode_mark_sick(ip, XFS_SICK_INO_CORE);
 			return -EFSCORRUPTED;
 		}
 		break;
 	default:
 		xfs_inode_verifier_error(ip, -EFSCORRUPTED, __func__, dip,
 				sizeof(*dip), __this_address);
 		xfs_inode_mark_sick(ip, XFS_SICK_INO_CORE);
 		return -EFSCORRUPTED;
 	}
 }

 static uint16_t
 xfs_dfork_attr_shortform_size(
 	struct xfs_dinode		*dip)
 {
 	struct xfs_attr_sf_hdr		*sf = XFS_DFORK_APTR(dip);

 	return be16_to_cpu(sf->totsize);
 }

 void
 xfs_ifork_init_attr(
 	struct xfs_inode	*ip,
 	enum xfs_dinode_fmt	format,
 	xfs_extnum_t		nextents)
 {
 	/*
 	 * Initialize the extent count early, as the per-format routines may
 	 * depend on it.  Use release semantics to set needextents /after/ we
 	 * set the format. This ensures that we can use acquire semantics on
 	 * needextents in xfs_need_iread_extents() and be guaranteed to see a
 	 * valid format value after that load.
 	 */
 	ip->i_af.if_format = format;
 	ip->i_af.if_nextents = nextents;
 	smp_store_release(&ip->i_af.if_needextents,
 			   ip->i_af.if_format == XFS_DINODE_FMT_BTREE ? 1 : 0);
 }

 void
 xfs_ifork_zap_attr(
 	struct xfs_inode	*ip)
 {
 	xfs_idestroy_fork(&ip->i_af);
 	memset(&ip->i_af, 0, sizeof(struct xfs_ifork));
 	ip->i_af.if_format = XFS_DINODE_FMT_EXTENTS;
 }

 int
 xfs_iformat_attr_fork(
 	struct xfs_inode	*ip,
 	struct xfs_dinode	*dip)
 {
 	xfs_extnum_t		naextents = xfs_dfork_attr_extents(dip);
 	int			error = 0;

 	/*
 	 * Initialize the extent count early, as the per-format routines may
 	 * depend on it.
 	 */
 	xfs_ifork_init_attr(ip, dip->di_aformat, naextents);

 	switch (ip->i_af.if_format) {
 	case XFS_DINODE_FMT_LOCAL:
 		error = xfs_iformat_local(ip, dip, XFS_ATTR_FORK,
 				xfs_dfork_attr_shortform_size(dip));
 		if (!error)
 			error = xfs_ifork_verify_local_attr(ip);
 		break;
 	case XFS_DINODE_FMT_EXTENTS:
 		error = xfs_iformat_extents(ip, dip, XFS_ATTR_FORK);
 		break;
 	case XFS_DINODE_FMT_BTREE:
 		error = xfs_iformat_btree(ip, dip, XFS_ATTR_FORK);
 		break;
 	default:
 		xfs_inode_verifier_error(ip, error, __func__, dip,
 				sizeof(*dip), __this_address);
 		xfs_inode_mark_sick(ip, XFS_SICK_INO_CORE);
 		error = -EFSCORRUPTED;
 		break;
 	}

 	if (error)
 		xfs_ifork_zap_attr(ip);
 	return error;
 }

 /*
  * Reallocate the space for if_broot based on the number of records
  * being added or deleted as indicated in rec_diff.  Move the records
  * and pointers in if_broot to fit the new size.  When shrinking this
  * will eliminate holes between the records and pointers created by
  * the caller.  When growing this will create holes to be filled in
  * by the caller.
  *
  * The caller must not request to add more records than would fit in
  * the on-disk inode root.  If the if_broot is currently NULL, then
  * if we are adding records, one will be allocated.  The caller must also
  * not request that the number of records go below zero, although
  * it can go to zero.
  *
  * ip -- the inode whose if_broot area is changing
  * ext_diff -- the change in the number of records, positive or negative,
  *	 requested for the if_broot array.
  */
 void
 xfs_iroot_realloc(
 	xfs_inode_t		*ip,
 	int			rec_diff,
 	int			whichfork)
 {
 	struct xfs_mount	*mp = ip->i_mount;
 	int			cur_max;
 	struct xfs_ifork	*ifp;
 	struct xfs_btree_block	*new_broot;
 	int			new_max;
 	size_t			new_size;
 	char			*np;
 	char			*op;

 	/*
 	 * Handle the degenerate case quietly.
 	 */
 	if (rec_diff == 0) {
 		return;
 	}

 	ifp = xfs_ifork_ptr(ip, whichfork);
 	if (rec_diff > 0) {
 		/*
 		 * If there wasn't any memory allocated before, just
 		 * allocate it now and get out.
 		 */
 		if (ifp->if_broot_bytes == 0) {
 			new_size = XFS_BMAP_BROOT_SPACE_CALC(mp, rec_diff);
 			ifp->if_broot = kmalloc(new_size,
 						GFP_KERNEL | __GFP_NOFAIL);
 			ifp->if_broot_bytes = (int)new_size;
 			return;
 		}

 		/*
 		 * If there is already an existing if_broot, then we need
 		 * to realloc() it and shift the pointers to their new
 		 * location.  The records don't change location because
 		 * they are kept butted up against the btree block header.
 		 */
 		cur_max = xfs_bmbt_maxrecs(mp, ifp->if_broot_bytes, 0);
 		new_max = cur_max + rec_diff;
 		new_size = XFS_BMAP_BROOT_SPACE_CALC(mp, new_max);
 		ifp->if_broot = krealloc(ifp->if_broot, new_size,
 					 GFP_KERNEL | __GFP_NOFAIL);
 		op = (char *)XFS_BMAP_BROOT_PTR_ADDR(mp, ifp->if_broot, 1,
 						     ifp->if_broot_bytes);
 		np = (char *)XFS_BMAP_BROOT_PTR_ADDR(mp, ifp->if_broot, 1,
 						     (int)new_size);
 		ifp->if_broot_bytes = (int)new_size;
 		ASSERT(XFS_BMAP_BMDR_SPACE(ifp->if_broot) <=
 			xfs_inode_fork_size(ip, whichfork));
 		memmove(np, op, cur_max * (uint)sizeof(xfs_fsblock_t));
 		return;
 	}

 	/*
 	 * rec_diff is less than 0.  In this case, we are shrinking the
 	 * if_broot buffer.  It must already exist.  If we go to zero
 	 * records, just get rid of the root and clear the status bit.
 	 */
 	ASSERT((ifp->if_broot != NULL) && (ifp->if_broot_bytes > 0));
 	cur_max = xfs_bmbt_maxrecs(mp, ifp->if_broot_bytes, 0);
 	new_max = cur_max + rec_diff;
 	ASSERT(new_max >= 0);
 	if (new_max > 0)
 		new_size = XFS_BMAP_BROOT_SPACE_CALC(mp, new_max);
 	else
 		new_size = 0;
 	if (new_size > 0) {
 		new_broot = kmalloc(new_size, GFP_KERNEL | __GFP_NOFAIL);
 		/*
 		 * First copy over the btree block header.
 		 */
 		memcpy(new_broot, ifp->if_broot,
 			XFS_BMBT_BLOCK_LEN(ip->i_mount));
 	} else {
 		new_broot = NULL;
 	}

 	/*
 	 * Only copy the records and pointers if there are any.
 	 */
 	if (new_max > 0) {
 		/*
 		 * First copy the records.
 		 */
 		op = (char *)XFS_BMBT_REC_ADDR(mp, ifp->if_broot, 1);
 		np = (char *)XFS_BMBT_REC_ADDR(mp, new_broot, 1);
 		memcpy(np, op, new_max * (uint)sizeof(xfs_bmbt_rec_t));

 		/*
 		 * Then copy the pointers.
 		 */
 		op = (char *)XFS_BMAP_BROOT_PTR_ADDR(mp, ifp->if_broot, 1,
 						     ifp->if_broot_bytes);
 		np = (char *)XFS_BMAP_BROOT_PTR_ADDR(mp, new_broot, 1,
 						     (int)new_size);
 		memcpy(np, op, new_max * (uint)sizeof(xfs_fsblock_t));
 	}
 	kfree(ifp->if_broot);
 	ifp->if_broot = new_broot;
 	ifp->if_broot_bytes = (int)new_size;
 	if (ifp->if_broot)
 		ASSERT(XFS_BMAP_BMDR_SPACE(ifp->if_broot) <=
 			xfs_inode_fork_size(ip, whichfork));
 	return;
 }


 /*
  * This is called when the amount of space needed for if_data
  * is increased or decreased.  The change in size is indicated by
  * the number of bytes that need to be added or deleted in the
  * byte_diff parameter.
  *
  * If the amount of space needed has decreased below the size of the
  * inline buffer, then switch to using the inline buffer.  Otherwise,
  * use krealloc() or kmalloc() to adjust the size of the buffer
  * to what is needed.
  *
  * ip -- the inode whose if_data area is changing
  * byte_diff -- the change in the number of bytes, positive or negative,
  *	 requested for the if_data array.
  */
 void *
 xfs_idata_realloc(
 	struct xfs_inode	*ip,
 	int64_t			byte_diff,
 	int			whichfork)
 {
 	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
 	int64_t			new_size = ifp->if_bytes + byte_diff;

 	ASSERT(new_size >= 0);
 	ASSERT(new_size <= xfs_inode_fork_size(ip, whichfork));

 	if (byte_diff) {
 		ifp->if_data = krealloc(ifp->if_data, new_size,
 					GFP_KERNEL | __GFP_NOFAIL);
 		if (new_size == 0)
 			ifp->if_data = NULL;
 		ifp->if_bytes = new_size;
 	}

 	return ifp->if_data;
 }

 /* Free all memory and reset a fork back to its initial state. */
 void
 xfs_idestroy_fork(
 	struct xfs_ifork	*ifp)
 {
 	if (ifp->if_broot != NULL) {
 		kfree(ifp->if_broot);
 		ifp->if_broot = NULL;
 	}

 	switch (ifp->if_format) {
 	case XFS_DINODE_FMT_LOCAL:
 		kfree(ifp->if_data);
 		ifp->if_data = NULL;
 		break;
 	case XFS_DINODE_FMT_EXTENTS:
 	case XFS_DINODE_FMT_BTREE:
 		if (ifp->if_height)
 			xfs_iext_destroy(ifp);
 		break;
 	}
 }

 /*
  * Convert in-core extents to on-disk form
  *
  * In the case of the data fork, the in-core and on-disk fork sizes can be
  * different due to delayed allocation extents. We only copy on-disk extents
  * here, so callers must always use the physical fork size to determine the
  * size of the buffer passed to this routine.  We will return the size actually
  * used.
  */
 int
 xfs_iextents_copy(
 	struct xfs_inode	*ip,
 	struct xfs_bmbt_rec	*dp,
 	int			whichfork)
 {
 	int			state = xfs_bmap_fork_to_state(whichfork);
 	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
 	struct xfs_iext_cursor	icur;
 	struct xfs_bmbt_irec	rec;
 	int64_t			copied = 0;

 	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL | XFS_ILOCK_SHARED);
 	ASSERT(ifp->if_bytes > 0);

 	for_each_xfs_iext(ifp, &icur, &rec) {
 		if (isnullstartblock(rec.br_startblock))
 			continue;
 		ASSERT(xfs_bmap_validate_extent(ip, whichfork, &rec) == NULL);
 		xfs_bmbt_disk_set_all(dp, &rec);
 		trace_xfs_write_extent(ip, &icur, state, _RET_IP_);
 		copied += sizeof(struct xfs_bmbt_rec);
 		dp++;
 	}

 	ASSERT(copied > 0);
 	ASSERT(copied <= ifp->if_bytes);
 	return copied;
 }

 /*
  * Each of the following cases stores data into the same region
  * of the on-disk inode, so only one of them can be valid at
  * any given time. While it is possible to have conflicting formats
  * and log flags, e.g. having XFS_ILOG_?DATA set when the fork is
  * in EXTENTS format, this can only happen when the fork has
  * changed formats after being modified but before being flushed.
  * In these cases, the format always takes precedence, because the
  * format indicates the current state of the fork.
  */
 void
 xfs_iflush_fork(
 	struct xfs_inode	*ip,
 	struct xfs_dinode	*dip,
 	struct xfs_inode_log_item *iip,
 	int			whichfork)
 {
 	char			*cp;
 	struct xfs_ifork	*ifp;
 	xfs_mount_t		*mp;
 	static const short	brootflag[2] =
 		{ XFS_ILOG_DBROOT, XFS_ILOG_ABROOT };
 	static const short	dataflag[2] =
 		{ XFS_ILOG_DDATA, XFS_ILOG_ADATA };
 	static const short	extflag[2] =
 		{ XFS_ILOG_DEXT, XFS_ILOG_AEXT };

 	if (!iip)
 		return;
 	ifp = xfs_ifork_ptr(ip, whichfork);
 	/*
 	 * This can happen if we gave up in iformat in an error path,
 	 * for the attribute fork.
 	 */
 	if (!ifp) {
 		ASSERT(whichfork == XFS_ATTR_FORK);
 		return;
 	}
 	cp = XFS_DFORK_PTR(dip, whichfork);
 	mp = ip->i_mount;
 	switch (ifp->if_format) {
 	case XFS_DINODE_FMT_LOCAL:
 		if ((iip->ili_fields & dataflag[whichfork]) &&
 		    (ifp->if_bytes > 0)) {
 			ASSERT(ifp->if_data != NULL);
 			ASSERT(ifp->if_bytes <= xfs_inode_fork_size(ip, whichfork));
 			memcpy(cp, ifp->if_data, ifp->if_bytes);
 		}
 		break;

 	case XFS_DINODE_FMT_EXTENTS:
 		if ((iip->ili_fields & extflag[whichfork]) &&
 		    (ifp->if_bytes > 0)) {
 			ASSERT(ifp->if_nextents > 0);
 			(void)xfs_iextents_copy(ip, (xfs_bmbt_rec_t *)cp,
 				whichfork);
 		}
 		break;

 	case XFS_DINODE_FMT_BTREE:
 		if ((iip->ili_fields & brootflag[whichfork]) &&
 		    (ifp->if_broot_bytes > 0)) {
 			ASSERT(ifp->if_broot != NULL);
 			ASSERT(XFS_BMAP_BMDR_SPACE(ifp->if_broot) <=
 			        xfs_inode_fork_size(ip, whichfork));
 			xfs_bmbt_to_bmdr(mp, ifp->if_broot, ifp->if_broot_bytes,
 				(xfs_bmdr_block_t *)cp,
 				XFS_DFORK_SIZE(dip, mp, whichfork));
 		}
 		break;

 	case XFS_DINODE_FMT_DEV:
 		if (iip->ili_fields & XFS_ILOG_DEV) {
 			ASSERT(whichfork == XFS_DATA_FORK);
 			xfs_dinode_put_rdev(dip,
 					linux_to_xfs_dev_t(VFS_I(ip)->i_rdev));
 		}
 		break;

 	default:
 		ASSERT(0);
 		break;
 	}
 }

 /* Convert bmap state flags to an inode fork. */
 struct xfs_ifork *
 xfs_iext_state_to_fork(
 	struct xfs_inode	*ip,
 	int			state)
 {
 	if (state & BMAP_COWFORK)
 		return ip->i_cowfp;
 	else if (state & BMAP_ATTRFORK)
 		return &ip->i_af;
 	return &ip->i_df;
 }

 /*
  * Initialize an inode's copy-on-write fork.
  */
 void
 xfs_ifork_init_cow(
 	struct xfs_inode	*ip)
 {
 	if (ip->i_cowfp)
 		return;

 	ip->i_cowfp = kmem_cache_zalloc(xfs_ifork_cache,
 				GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);
 	ip->i_cowfp->if_format = XFS_DINODE_FMT_EXTENTS;
 }

 /* Verify the inline contents of the data fork of an inode. */
 int
 xfs_ifork_verify_local_data(
 	struct xfs_inode	*ip)
 {
 	xfs_failaddr_t		fa = NULL;

 	switch (VFS_I(ip)->i_mode & S_IFMT) {
 	case S_IFDIR: {
 		struct xfs_mount	*mp = ip->i_mount;
 		struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, XFS_DATA_FORK);
 		struct xfs_dir2_sf_hdr	*sfp = ifp->if_data;

 		fa = xfs_dir2_sf_verify(mp, sfp, ifp->if_bytes);
 		break;
 	}
 	case S_IFLNK: {
 		struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, XFS_DATA_FORK);

 		fa = xfs_symlink_shortform_verify(ifp->if_data, ifp->if_bytes);
 		break;
 	}
 	default:
 		break;
 	}

 	if (fa) {
 		xfs_inode_verifier_error(ip, -EFSCORRUPTED, "data fork",
 				ip->i_df.if_data, ip->i_df.if_bytes, fa);
 		return -EFSCORRUPTED;
 	}

 	return 0;
 }

 /* Verify the inline contents of the attr fork of an inode. */
 int
 xfs_ifork_verify_local_attr(
 	struct xfs_inode	*ip)
 {
 	struct xfs_ifork	*ifp = &ip->i_af;
 	xfs_failaddr_t		fa;

 	if (!xfs_inode_has_attr_fork(ip)) {
 		fa = __this_address;
 	} else {
 		struct xfs_ifork		*ifp = &ip->i_af;

 		ASSERT(ifp->if_format == XFS_DINODE_FMT_LOCAL);
 		fa = xfs_attr_shortform_verify(ifp->if_data, ifp->if_bytes);
 	}
 	if (fa) {
 		xfs_inode_verifier_error(ip, -EFSCORRUPTED, "attr fork",
 				ifp->if_data, ifp->if_bytes, fa);
 		return -EFSCORRUPTED;
 	}

 	return 0;
 }

 /*
  * Check if the inode fork supports adding nr_to_add more extents.
  *
  * If it doesn't but we can upgrade it to large extent counters, do the upgrade.
  * If we can't upgrade or are already using big counters but still can't fit the
  * additional extents, return -EFBIG.
  */
 int
 xfs_iext_count_extend(
 	struct xfs_trans	*tp,
 	struct xfs_inode	*ip,
 	int			whichfork,
 	uint			nr_to_add)
 {
 	struct xfs_mount	*mp = ip->i_mount;
 	bool			has_large =
 		xfs_inode_has_large_extent_counts(ip);
 	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
 	uint64_t		nr_exts;

 	ASSERT(nr_to_add <= XFS_MAX_EXTCNT_UPGRADE_NR);

 	if (whichfork == XFS_COW_FORK)
 		return 0;

 	/* no point in upgrading if if_nextents overflows */
 	nr_exts = ifp->if_nextents + nr_to_add;
 	if (nr_exts < ifp->if_nextents)
 		return -EFBIG;

 	if (XFS_TEST_ERROR(false, mp, XFS_ERRTAG_REDUCE_MAX_IEXTENTS) &&
 	    nr_exts > 10)
 		return -EFBIG;

 	if (nr_exts > xfs_iext_max_nextents(has_large, whichfork)) {
 		if (has_large || !xfs_has_large_extent_counts(mp))
 			return -EFBIG;
 		ip->i_diflags2 |= XFS_DIFLAG2_NREXT64;
 		xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 	}
 	return 0;
 }

 /* Decide if a file mapping is on the realtime device or not. */
 bool
 xfs_ifork_is_realtime(
 	struct xfs_inode	*ip,
 	int			whichfork)
 {
 	return XFS_IS_REALTIME_INODE(ip) && whichfork != XFS_ATTR_FORK;
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Copyright (c) 2000-2006 Silicon Graphics, Inc.
	* All Rights Reserved.
	*/

	#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_inode.h"
	#include "xfs_trans.h"
	#include "xfs_inode_item.h"
	#include "xfs_btree.h"
	#include "xfs_bmap_btree.h"
	#include "xfs_bmap.h"
	#include "xfs_error.h"
	#include "xfs_trace.h"
	#include "xfs_da_format.h"
	#include "xfs_da_btree.h"
	#include "xfs_dir2_priv.h"
	#include "xfs_attr_leaf.h"
	#include "xfs_types.h"
	#include "xfs_errortag.h"
	#include "xfs_health.h"
	#include "xfs_symlink_remote.h"

	struct kmem_cache *xfs_ifork_cache;

	void
	xfs_init_local_fork(
	struct xfs_inode *ip,
	int whichfork,
	const void *data,
	int64_t size)
	{
	struct xfs_ifork *ifp = xfs_ifork_ptr(ip, whichfork);
	int mem_size = size;
	bool zero_terminate;

	/*
	* If we are using the local fork to store a symlink body we need to
	* zero-terminate it so that we can pass it back to the VFS directly.
	* Overallocate the in-memory fork by one for that and add a zero
	* to terminate it below.
	*/
	zero_terminate = S_ISLNK(VFS_I(ip)->i_mode);
	if (zero_terminate)
	mem_size++;

	if (size) {
	char *new_data = kmalloc(mem_size,
	GFP_KERNEL \| __GFP_NOLOCKDEP \| __GFP_NOFAIL);

	memcpy(new_data, data, size);
	if (zero_terminate)
	new_data[size] = '\0';

	ifp->if_data = new_data;
	} else {
	ifp->if_data = NULL;
	}

	ifp->if_bytes = size;
	}

	/*
	* The file is in-lined in the on-disk inode.
	*/
	STATIC int
	xfs_iformat_local(
	struct xfs_inode *ip,
	struct xfs_dinode *dip,
	int whichfork,
	int size)
	{
	/*
	* If the size is unreasonable, then something
	* is wrong and we just bail out rather than crash in
	* kmalloc() or memcpy() below.
	*/
	if (unlikely(size > XFS_DFORK_SIZE(dip, ip->i_mount, whichfork))) {
	xfs_warn(ip->i_mount,
	"corrupt inode %llu (bad size %d for local fork, size = %zd).",
	(unsigned long long) ip->i_ino, size,
	XFS_DFORK_SIZE(dip, ip->i_mount, whichfork));
	xfs_inode_verifier_error(ip, -EFSCORRUPTED,
	"xfs_iformat_local", dip, sizeof(*dip),
	__this_address);
	xfs_inode_mark_sick(ip, XFS_SICK_INO_CORE);
	return -EFSCORRUPTED;
	}

	xfs_init_local_fork(ip, whichfork, XFS_DFORK_PTR(dip, whichfork), size);
	return 0;
	}

	/*
	* The file consists of a set of extents all of which fit into the on-disk
	* inode.
	*/
	STATIC int
	xfs_iformat_extents(
	struct xfs_inode *ip,
	struct xfs_dinode *dip,
	int whichfork)
	{
	struct xfs_mount *mp = ip->i_mount;
	struct xfs_ifork *ifp = xfs_ifork_ptr(ip, whichfork);
	int state = xfs_bmap_fork_to_state(whichfork);
	xfs_extnum_t nex = xfs_dfork_nextents(dip, whichfork);
	int size = nex * sizeof(xfs_bmbt_rec_t);
	struct xfs_iext_cursor icur;
	struct xfs_bmbt_rec *dp;
	struct xfs_bmbt_irec new;
	int i;

	/*
	* If the number of extents is unreasonable, then something is wrong and
	* we just bail out rather than crash in kmalloc() or memcpy() below.
	*/
	if (unlikely(size < 0 \|\| size > XFS_DFORK_SIZE(dip, mp, whichfork))) {
	xfs_warn(ip->i_mount, "corrupt inode %llu ((a)extents = %llu).",
	ip->i_ino, nex);
	xfs_inode_verifier_error(ip, -EFSCORRUPTED,
	"xfs_iformat_extents(1)", dip, sizeof(*dip),
	__this_address);
	xfs_inode_mark_sick(ip, XFS_SICK_INO_CORE);
	return -EFSCORRUPTED;
	}

	ifp->if_bytes = 0;
	ifp->if_data = NULL;
	ifp->if_height = 0;
	if (size) {
	dp = (xfs_bmbt_rec_t *) XFS_DFORK_PTR(dip, whichfork);

	xfs_iext_first(ifp, &icur);
	for (i = 0; i < nex; i++, dp++) {
	xfs_failaddr_t fa;

	xfs_bmbt_disk_get_all(dp, &new);
	fa = xfs_bmap_validate_extent(ip, whichfork, &new);
	if (fa) {
	xfs_inode_verifier_error(ip, -EFSCORRUPTED,
	"xfs_iformat_extents(2)",
	dp, sizeof(*dp), fa);
	xfs_inode_mark_sick(ip, XFS_SICK_INO_CORE);
	return xfs_bmap_complain_bad_rec(ip, whichfork,
	fa, &new);
	}

	xfs_iext_insert(ip, &icur, &new, state);
	trace_xfs_read_extent(ip, &icur, state, _THIS_IP_);
	xfs_iext_next(ifp, &icur);
	}
	}
	return 0;
	}

	/*
	* The file has too many extents to fit into
	* the inode, so they are in B-tree format.
	* Allocate a buffer for the root of the B-tree
	* and copy the root into it. The i_extents
	* field will remain NULL until all of the
	* extents are read in (when they are needed).
	*/
	STATIC int
	xfs_iformat_btree(
	struct xfs_inode *ip,
	struct xfs_dinode *dip,
	int whichfork)
	{
	struct xfs_mount *mp = ip->i_mount;
	xfs_bmdr_block_t *dfp;
	struct xfs_ifork *ifp;
	/* REFERENCED */
	int nrecs;
	int size;
	int level;

	ifp = xfs_ifork_ptr(ip, whichfork);
	dfp = (xfs_bmdr_block_t *)XFS_DFORK_PTR(dip, whichfork);
	size = XFS_BMAP_BROOT_SPACE(mp, dfp);
	nrecs = be16_to_cpu(dfp->bb_numrecs);
	level = be16_to_cpu(dfp->bb_level);

	/*
	* blow out if -- fork has less extents than can fit in
	* fork (fork shouldn't be a btree format), root btree
	* block has more records than can fit into the fork,
	* or the number of extents is greater than the number of
	* blocks.
	*/
	if (unlikely(ifp->if_nextents <= XFS_IFORK_MAXEXT(ip, whichfork) \|\|
	nrecs == 0 \|\|
	XFS_BMDR_SPACE_CALC(nrecs) >
	XFS_DFORK_SIZE(dip, mp, whichfork) \|\|
	ifp->if_nextents > ip->i_nblocks) \|\|
	level == 0 \|\| level > XFS_BM_MAXLEVELS(mp, whichfork)) {
	xfs_warn(mp, "corrupt inode %llu (btree).",
	(unsigned long long) ip->i_ino);
	xfs_inode_verifier_error(ip, -EFSCORRUPTED,
	"xfs_iformat_btree", dfp, size,
	__this_address);
	xfs_inode_mark_sick(ip, XFS_SICK_INO_CORE);
	return -EFSCORRUPTED;
	}

	ifp->if_broot_bytes = size;
	ifp->if_broot = kmalloc(size,
	GFP_KERNEL \| __GFP_NOLOCKDEP \| __GFP_NOFAIL);
	ASSERT(ifp->if_broot != NULL);
	/*
	* Copy and convert from the on-disk structure
	* to the in-memory structure.
	*/
	xfs_bmdr_to_bmbt(ip, dfp, XFS_DFORK_SIZE(dip, ip->i_mount, whichfork),
	ifp->if_broot, size);

	ifp->if_bytes = 0;
	ifp->if_data = NULL;
	ifp->if_height = 0;
	return 0;
	}

	int
	xfs_iformat_data_fork(
	struct xfs_inode *ip,
	struct xfs_dinode *dip)
	{
	struct inode *inode = VFS_I(ip);
	int error;

	/*
	* Initialize the extent count early, as the per-format routines may
	* depend on it. Use release semantics to set needextents /after/ we
	* set the format. This ensures that we can use acquire semantics on
	* needextents in xfs_need_iread_extents() and be guaranteed to see a
	* valid format value after that load.
	*/
	ip->i_df.if_format = dip->di_format;
	ip->i_df.if_nextents = xfs_dfork_data_extents(dip);
	smp_store_release(&ip->i_df.if_needextents,
	ip->i_df.if_format == XFS_DINODE_FMT_BTREE ? 1 : 0);

	switch (inode->i_mode & S_IFMT) {
	case S_IFIFO:
	case S_IFCHR:
	case S_IFBLK:
	case S_IFSOCK:
	ip->i_disk_size = 0;
	inode->i_rdev = xfs_to_linux_dev_t(xfs_dinode_get_rdev(dip));
	return 0;
	case S_IFREG:
	case S_IFLNK:
	case S_IFDIR:
	switch (ip->i_df.if_format) {
	case XFS_DINODE_FMT_LOCAL:
	error = xfs_iformat_local(ip, dip, XFS_DATA_FORK,
	be64_to_cpu(dip->di_size));
	if (!error)
	error = xfs_ifork_verify_local_data(ip);
	return error;
	case XFS_DINODE_FMT_EXTENTS:
	return xfs_iformat_extents(ip, dip, XFS_DATA_FORK);
	case XFS_DINODE_FMT_BTREE:
	return xfs_iformat_btree(ip, dip, XFS_DATA_FORK);
	default:
	xfs_inode_verifier_error(ip, -EFSCORRUPTED, __func__,
	dip, sizeof(*dip), __this_address);
	xfs_inode_mark_sick(ip, XFS_SICK_INO_CORE);
	return -EFSCORRUPTED;
	}
	break;
	default:
	xfs_inode_verifier_error(ip, -EFSCORRUPTED, __func__, dip,
	sizeof(*dip), __this_address);
	xfs_inode_mark_sick(ip, XFS_SICK_INO_CORE);
	return -EFSCORRUPTED;
	}
	}

	static uint16_t
	xfs_dfork_attr_shortform_size(
	struct xfs_dinode *dip)
	{
	struct xfs_attr_sf_hdr *sf = XFS_DFORK_APTR(dip);

	return be16_to_cpu(sf->totsize);
	}

	void
	xfs_ifork_init_attr(
	struct xfs_inode *ip,
	enum xfs_dinode_fmt format,
	xfs_extnum_t nextents)
	{
	/*
	* Initialize the extent count early, as the per-format routines may
	* depend on it. Use release semantics to set needextents /after/ we
	* set the format. This ensures that we can use acquire semantics on
	* needextents in xfs_need_iread_extents() and be guaranteed to see a
	* valid format value after that load.
	*/
	ip->i_af.if_format = format;
	ip->i_af.if_nextents = nextents;
	smp_store_release(&ip->i_af.if_needextents,
	ip->i_af.if_format == XFS_DINODE_FMT_BTREE ? 1 : 0);
	}

	void
	xfs_ifork_zap_attr(
	struct xfs_inode *ip)
	{
	xfs_idestroy_fork(&ip->i_af);
	memset(&ip->i_af, 0, sizeof(struct xfs_ifork));
	ip->i_af.if_format = XFS_DINODE_FMT_EXTENTS;
	}

	int
	xfs_iformat_attr_fork(
	struct xfs_inode *ip,
	struct xfs_dinode *dip)
	{
	xfs_extnum_t naextents = xfs_dfork_attr_extents(dip);
	int error = 0;

	/*
	* Initialize the extent count early, as the per-format routines may
	* depend on it.
	*/
	xfs_ifork_init_attr(ip, dip->di_aformat, naextents);

	switch (ip->i_af.if_format) {
	case XFS_DINODE_FMT_LOCAL:
	error = xfs_iformat_local(ip, dip, XFS_ATTR_FORK,
	xfs_dfork_attr_shortform_size(dip));
	if (!error)
	error = xfs_ifork_verify_local_attr(ip);
	break;
	case XFS_DINODE_FMT_EXTENTS:
	error = xfs_iformat_extents(ip, dip, XFS_ATTR_FORK);
	break;
	case XFS_DINODE_FMT_BTREE:
	error = xfs_iformat_btree(ip, dip, XFS_ATTR_FORK);
	break;
	default:
	xfs_inode_verifier_error(ip, error, __func__, dip,
	sizeof(*dip), __this_address);
	xfs_inode_mark_sick(ip, XFS_SICK_INO_CORE);
	error = -EFSCORRUPTED;
	break;
	}

	if (error)
	xfs_ifork_zap_attr(ip);
	return error;
	}

	/*
	* Reallocate the space for if_broot based on the number of records
	* being added or deleted as indicated in rec_diff. Move the records
	* and pointers in if_broot to fit the new size. When shrinking this
	* will eliminate holes between the records and pointers created by
	* the caller. When growing this will create holes to be filled in
	* by the caller.
	*
	* The caller must not request to add more records than would fit in
	* the on-disk inode root. If the if_broot is currently NULL, then
	* if we are adding records, one will be allocated. The caller must also
	* not request that the number of records go below zero, although
	* it can go to zero.
	*
	* ip -- the inode whose if_broot area is changing
	* ext_diff -- the change in the number of records, positive or negative,
	* requested for the if_broot array.
	*/
	void
	xfs_iroot_realloc(
	xfs_inode_t *ip,
	int rec_diff,
	int whichfork)
	{
	struct xfs_mount *mp = ip->i_mount;
	int cur_max;
	struct xfs_ifork *ifp;
	struct xfs_btree_block *new_broot;
	int new_max;
	size_t new_size;
	char *np;
	char *op;

	/*
	* Handle the degenerate case quietly.
	*/
	if (rec_diff == 0) {
	return;
	}

	ifp = xfs_ifork_ptr(ip, whichfork);
	if (rec_diff > 0) {
	/*
	* If there wasn't any memory allocated before, just
	* allocate it now and get out.
	*/
	if (ifp->if_broot_bytes == 0) {
	new_size = XFS_BMAP_BROOT_SPACE_CALC(mp, rec_diff);
	ifp->if_broot = kmalloc(new_size,
	GFP_KERNEL \| __GFP_NOFAIL);
	ifp->if_broot_bytes = (int)new_size;
	return;
	}

	/*
	* If there is already an existing if_broot, then we need
	* to realloc() it and shift the pointers to their new
	* location. The records don't change location because
	* they are kept butted up against the btree block header.
	*/
	cur_max = xfs_bmbt_maxrecs(mp, ifp->if_broot_bytes, 0);
	new_max = cur_max + rec_diff;
	new_size = XFS_BMAP_BROOT_SPACE_CALC(mp, new_max);
	ifp->if_broot = krealloc(ifp->if_broot, new_size,
	GFP_KERNEL \| __GFP_NOFAIL);
	op = (char *)XFS_BMAP_BROOT_PTR_ADDR(mp, ifp->if_broot, 1,
	ifp->if_broot_bytes);
	np = (char *)XFS_BMAP_BROOT_PTR_ADDR(mp, ifp->if_broot, 1,
	(int)new_size);
	ifp->if_broot_bytes = (int)new_size;
	ASSERT(XFS_BMAP_BMDR_SPACE(ifp->if_broot) <=
	xfs_inode_fork_size(ip, whichfork));
	memmove(np, op, cur_max * (uint)sizeof(xfs_fsblock_t));
	return;
	}

	/*
	* rec_diff is less than 0. In this case, we are shrinking the
	* if_broot buffer. It must already exist. If we go to zero
	* records, just get rid of the root and clear the status bit.
	*/
	ASSERT((ifp->if_broot != NULL) && (ifp->if_broot_bytes > 0));
	cur_max = xfs_bmbt_maxrecs(mp, ifp->if_broot_bytes, 0);
	new_max = cur_max + rec_diff;
	ASSERT(new_max >= 0);
	if (new_max > 0)
	new_size = XFS_BMAP_BROOT_SPACE_CALC(mp, new_max);
	else
	new_size = 0;
	if (new_size > 0) {
	new_broot = kmalloc(new_size, GFP_KERNEL \| __GFP_NOFAIL);
	/*
	* First copy over the btree block header.
	*/
	memcpy(new_broot, ifp->if_broot,
	XFS_BMBT_BLOCK_LEN(ip->i_mount));
	} else {
	new_broot = NULL;
	}

	/*
	* Only copy the records and pointers if there are any.
	*/
	if (new_max > 0) {
	/*
	* First copy the records.
	*/
	op = (char *)XFS_BMBT_REC_ADDR(mp, ifp->if_broot, 1);
	np = (char *)XFS_BMBT_REC_ADDR(mp, new_broot, 1);
	memcpy(np, op, new_max * (uint)sizeof(xfs_bmbt_rec_t));

	/*
	* Then copy the pointers.
	*/
	op = (char *)XFS_BMAP_BROOT_PTR_ADDR(mp, ifp->if_broot, 1,
	ifp->if_broot_bytes);
	np = (char *)XFS_BMAP_BROOT_PTR_ADDR(mp, new_broot, 1,
	(int)new_size);
	memcpy(np, op, new_max * (uint)sizeof(xfs_fsblock_t));
	}
	kfree(ifp->if_broot);
	ifp->if_broot = new_broot;
	ifp->if_broot_bytes = (int)new_size;
	if (ifp->if_broot)
	ASSERT(XFS_BMAP_BMDR_SPACE(ifp->if_broot) <=
	xfs_inode_fork_size(ip, whichfork));
	return;
	}


	/*
	* This is called when the amount of space needed for if_data
	* is increased or decreased. The change in size is indicated by
	* the number of bytes that need to be added or deleted in the
	* byte_diff parameter.
	*
	* If the amount of space needed has decreased below the size of the
	* inline buffer, then switch to using the inline buffer. Otherwise,
	* use krealloc() or kmalloc() to adjust the size of the buffer
	* to what is needed.
	*
	* ip -- the inode whose if_data area is changing
	* byte_diff -- the change in the number of bytes, positive or negative,
	* requested for the if_data array.
	*/
	void *
	xfs_idata_realloc(
	struct xfs_inode *ip,
	int64_t byte_diff,
	int whichfork)
	{
	struct xfs_ifork *ifp = xfs_ifork_ptr(ip, whichfork);
	int64_t new_size = ifp->if_bytes + byte_diff;

	ASSERT(new_size >= 0);
	ASSERT(new_size <= xfs_inode_fork_size(ip, whichfork));

	if (byte_diff) {
	ifp->if_data = krealloc(ifp->if_data, new_size,
	GFP_KERNEL \| __GFP_NOFAIL);
	if (new_size == 0)
	ifp->if_data = NULL;
	ifp->if_bytes = new_size;
	}

	return ifp->if_data;
	}

	/* Free all memory and reset a fork back to its initial state. */
	void
	xfs_idestroy_fork(
	struct xfs_ifork *ifp)
	{
	if (ifp->if_broot != NULL) {
	kfree(ifp->if_broot);
	ifp->if_broot = NULL;
	}

	switch (ifp->if_format) {
	case XFS_DINODE_FMT_LOCAL:
	kfree(ifp->if_data);
	ifp->if_data = NULL;
	break;
	case XFS_DINODE_FMT_EXTENTS:
	case XFS_DINODE_FMT_BTREE:
	if (ifp->if_height)
	xfs_iext_destroy(ifp);
	break;
	}
	}

	/*
	* Convert in-core extents to on-disk form
	*
	* In the case of the data fork, the in-core and on-disk fork sizes can be
	* different due to delayed allocation extents. We only copy on-disk extents
	* here, so callers must always use the physical fork size to determine the
	* size of the buffer passed to this routine. We will return the size actually
	* used.
	*/
	int
	xfs_iextents_copy(
	struct xfs_inode *ip,
	struct xfs_bmbt_rec *dp,
	int whichfork)
	{
	int state = xfs_bmap_fork_to_state(whichfork);
	struct xfs_ifork *ifp = xfs_ifork_ptr(ip, whichfork);
	struct xfs_iext_cursor icur;
	struct xfs_bmbt_irec rec;
	int64_t copied = 0;

	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL \| XFS_ILOCK_SHARED);
	ASSERT(ifp->if_bytes > 0);

	for_each_xfs_iext(ifp, &icur, &rec) {
	if (isnullstartblock(rec.br_startblock))
	continue;
	ASSERT(xfs_bmap_validate_extent(ip, whichfork, &rec) == NULL);
	xfs_bmbt_disk_set_all(dp, &rec);
	trace_xfs_write_extent(ip, &icur, state, _RET_IP_);
	copied += sizeof(struct xfs_bmbt_rec);
	dp++;
	}

	ASSERT(copied > 0);
	ASSERT(copied <= ifp->if_bytes);
	return copied;
	}

	/*
	* Each of the following cases stores data into the same region
	* of the on-disk inode, so only one of them can be valid at
	* any given time. While it is possible to have conflicting formats
	* and log flags, e.g. having XFS_ILOG_?DATA set when the fork is
	* in EXTENTS format, this can only happen when the fork has
	* changed formats after being modified but before being flushed.
	* In these cases, the format always takes precedence, because the
	* format indicates the current state of the fork.
	*/
	void
	xfs_iflush_fork(
	struct xfs_inode *ip,
	struct xfs_dinode *dip,
	struct xfs_inode_log_item *iip,
	int whichfork)
	{
	char *cp;
	struct xfs_ifork *ifp;
	xfs_mount_t *mp;
	static const short brootflag[2] =
	{ XFS_ILOG_DBROOT, XFS_ILOG_ABROOT };
	static const short dataflag[2] =
	{ XFS_ILOG_DDATA, XFS_ILOG_ADATA };
	static const short extflag[2] =
	{ XFS_ILOG_DEXT, XFS_ILOG_AEXT };

	if (!iip)
	return;
	ifp = xfs_ifork_ptr(ip, whichfork);
	/*
	* This can happen if we gave up in iformat in an error path,
	* for the attribute fork.
	*/
	if (!ifp) {
	ASSERT(whichfork == XFS_ATTR_FORK);
	return;
	}
	cp = XFS_DFORK_PTR(dip, whichfork);
	mp = ip->i_mount;
	switch (ifp->if_format) {
	case XFS_DINODE_FMT_LOCAL:
	if ((iip->ili_fields & dataflag[whichfork]) &&
	(ifp->if_bytes > 0)) {
	ASSERT(ifp->if_data != NULL);
	ASSERT(ifp->if_bytes <= xfs_inode_fork_size(ip, whichfork));
	memcpy(cp, ifp->if_data, ifp->if_bytes);
	}
	break;

	case XFS_DINODE_FMT_EXTENTS:
	if ((iip->ili_fields & extflag[whichfork]) &&
	(ifp->if_bytes > 0)) {
	ASSERT(ifp->if_nextents > 0);
	(void)xfs_iextents_copy(ip, (xfs_bmbt_rec_t *)cp,
	whichfork);
	}
	break;

	case XFS_DINODE_FMT_BTREE:
	if ((iip->ili_fields & brootflag[whichfork]) &&
	(ifp->if_broot_bytes > 0)) {
	ASSERT(ifp->if_broot != NULL);
	ASSERT(XFS_BMAP_BMDR_SPACE(ifp->if_broot) <=
	xfs_inode_fork_size(ip, whichfork));
	xfs_bmbt_to_bmdr(mp, ifp->if_broot, ifp->if_broot_bytes,
	(xfs_bmdr_block_t *)cp,
	XFS_DFORK_SIZE(dip, mp, whichfork));
	}
	break;

	case XFS_DINODE_FMT_DEV:
	if (iip->ili_fields & XFS_ILOG_DEV) {
	ASSERT(whichfork == XFS_DATA_FORK);
	xfs_dinode_put_rdev(dip,
	linux_to_xfs_dev_t(VFS_I(ip)->i_rdev));
	}
	break;

	default:
	ASSERT(0);
	break;
	}
	}

	/* Convert bmap state flags to an inode fork. */
	struct xfs_ifork *
	xfs_iext_state_to_fork(
	struct xfs_inode *ip,
	int state)
	{
	if (state & BMAP_COWFORK)
	return ip->i_cowfp;
	else if (state & BMAP_ATTRFORK)
	return &ip->i_af;
	return &ip->i_df;
	}

	/*
	* Initialize an inode's copy-on-write fork.
	*/
	void
	xfs_ifork_init_cow(
	struct xfs_inode *ip)
	{
	if (ip->i_cowfp)
	return;

	ip->i_cowfp = kmem_cache_zalloc(xfs_ifork_cache,
	GFP_KERNEL \| __GFP_NOLOCKDEP \| __GFP_NOFAIL);
	ip->i_cowfp->if_format = XFS_DINODE_FMT_EXTENTS;
	}

	/* Verify the inline contents of the data fork of an inode. */
	int
	xfs_ifork_verify_local_data(
	struct xfs_inode *ip)
	{
	xfs_failaddr_t fa = NULL;

	switch (VFS_I(ip)->i_mode & S_IFMT) {
	case S_IFDIR: {
	struct xfs_mount *mp = ip->i_mount;
	struct xfs_ifork *ifp = xfs_ifork_ptr(ip, XFS_DATA_FORK);
	struct xfs_dir2_sf_hdr *sfp = ifp->if_data;

	fa = xfs_dir2_sf_verify(mp, sfp, ifp->if_bytes);
	break;
	}
	case S_IFLNK: {
	struct xfs_ifork *ifp = xfs_ifork_ptr(ip, XFS_DATA_FORK);

	fa = xfs_symlink_shortform_verify(ifp->if_data, ifp->if_bytes);
	break;
	}
	default:
	break;
	}

	if (fa) {
	xfs_inode_verifier_error(ip, -EFSCORRUPTED, "data fork",
	ip->i_df.if_data, ip->i_df.if_bytes, fa);
	return -EFSCORRUPTED;
	}

	return 0;
	}

	/* Verify the inline contents of the attr fork of an inode. */
	int
	xfs_ifork_verify_local_attr(
	struct xfs_inode *ip)
	{
	struct xfs_ifork *ifp = &ip->i_af;
	xfs_failaddr_t fa;

	if (!xfs_inode_has_attr_fork(ip)) {
	fa = __this_address;
	} else {
	struct xfs_ifork *ifp = &ip->i_af;

	ASSERT(ifp->if_format == XFS_DINODE_FMT_LOCAL);
	fa = xfs_attr_shortform_verify(ifp->if_data, ifp->if_bytes);
	}
	if (fa) {
	xfs_inode_verifier_error(ip, -EFSCORRUPTED, "attr fork",
	ifp->if_data, ifp->if_bytes, fa);
	return -EFSCORRUPTED;
	}

	return 0;
	}

	/*
	* Check if the inode fork supports adding nr_to_add more extents.
	*
	* If it doesn't but we can upgrade it to large extent counters, do the upgrade.
	* If we can't upgrade or are already using big counters but still can't fit the
	* additional extents, return -EFBIG.
	*/
	int
	xfs_iext_count_extend(
	struct xfs_trans *tp,
	struct xfs_inode *ip,
	int whichfork,
	uint nr_to_add)
	{
	struct xfs_mount *mp = ip->i_mount;
	bool has_large =
	xfs_inode_has_large_extent_counts(ip);
	struct xfs_ifork *ifp = xfs_ifork_ptr(ip, whichfork);
	uint64_t nr_exts;

	ASSERT(nr_to_add <= XFS_MAX_EXTCNT_UPGRADE_NR);

	if (whichfork == XFS_COW_FORK)
	return 0;

	/* no point in upgrading if if_nextents overflows */
	nr_exts = ifp->if_nextents + nr_to_add;
	if (nr_exts < ifp->if_nextents)
	return -EFBIG;

	if (XFS_TEST_ERROR(false, mp, XFS_ERRTAG_REDUCE_MAX_IEXTENTS) &&
	nr_exts > 10)
	return -EFBIG;

	if (nr_exts > xfs_iext_max_nextents(has_large, whichfork)) {
	if (has_large \|\| !xfs_has_large_extent_counts(mp))
	return -EFBIG;
	ip->i_diflags2 \|= XFS_DIFLAG2_NREXT64;
	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
	}
	return 0;
	}

	/* Decide if a file mapping is on the realtime device or not. */
	bool
	xfs_ifork_is_realtime(
	struct xfs_inode *ip,
	int whichfork)
	{
	return XFS_IS_REALTIME_INODE(ip) && whichfork != XFS_ATTR_FORK;
	}