Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2497 insertions, 0 deletions

diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
new file mode 100644
index 000000000..150cec85c
--- /dev/null
+++ b/fs/gfs2/bmap.c
@@ -0,0 +1,2497 @@
+/*
+ * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
+ * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.
+ *
+ * This copyrighted material is made available to anyone wishing to use,
+ * modify, copy, or redistribute it subject to the terms and conditions
+ * of the GNU General Public License version 2.
+ */
+
+#include <linux/spinlock.h>
+#include <linux/completion.h>
+#include <linux/buffer_head.h>
+#include <linux/blkdev.h>
+#include <linux/gfs2_ondisk.h>
+#include <linux/crc32.h>
+#include <linux/iomap.h>
+
+#include "gfs2.h"
+#include "incore.h"
+#include "bmap.h"
+#include "glock.h"
+#include "inode.h"
+#include "meta_io.h"
+#include "quota.h"
+#include "rgrp.h"
+#include "log.h"
+#include "super.h"
+#include "trans.h"
+#include "dir.h"
+#include "util.h"
+#include "aops.h"
+#include "trace_gfs2.h"
+
+/* This doesn't need to be that large as max 64 bit pointers in a 4k
+ * block is 512, so __u16 is fine for that. It saves stack space to
+ * keep it small.
+ */
+struct metapath {
+	struct buffer_head *mp_bh[GFS2_MAX_META_HEIGHT];
+	__u16 mp_list[GFS2_MAX_META_HEIGHT];
+	int mp_fheight; /* find_metapath height */
+	int mp_aheight; /* actual height (lookup height) */
+};
+
+static int punch_hole(struct gfs2_inode *ip, u64 offset, u64 length);
+
+/**
+ * gfs2_unstuffer_page - unstuff a stuffed inode into a block cached by a page
+ * @ip: the inode
+ * @dibh: the dinode buffer
+ * @block: the block number that was allocated
+ * @page: The (optional) page. This is looked up if @page is NULL
+ *
+ * Returns: errno
+ */
+
+static int gfs2_unstuffer_page(struct gfs2_inode *ip, struct buffer_head *dibh,
+			       u64 block, struct page *page)
+{
+	struct inode *inode = &ip->i_inode;
+	struct buffer_head *bh;
+	int release = 0;
+
+	if (!page || page->index) {
+		page = find_or_create_page(inode->i_mapping, 0, GFP_NOFS);
+		if (!page)
+			return -ENOMEM;
+		release = 1;
+	}
+
+	if (!PageUptodate(page)) {
+		void *kaddr = kmap(page);
+		u64 dsize = i_size_read(inode);
+ 
+		if (dsize > gfs2_max_stuffed_size(ip))
+			dsize = gfs2_max_stuffed_size(ip);
+
+		memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode), dsize);
+		memset(kaddr + dsize, 0, PAGE_SIZE - dsize);
+		kunmap(page);
+
+		SetPageUptodate(page);
+	}
+
+	if (!page_has_buffers(page))
+		create_empty_buffers(page, BIT(inode->i_blkbits),
+				     BIT(BH_Uptodate));
+
+	bh = page_buffers(page);
+
+	if (!buffer_mapped(bh))
+		map_bh(bh, inode->i_sb, block);
+
+	set_buffer_uptodate(bh);
+	if (gfs2_is_jdata(ip))
+		gfs2_trans_add_data(ip->i_gl, bh);
+	else {
+		mark_buffer_dirty(bh);
+		gfs2_ordered_add_inode(ip);
+	}
+
+	if (release) {
+		unlock_page(page);
+		put_page(page);
+	}
+
+	return 0;
+}
+
+/**
+ * gfs2_unstuff_dinode - Unstuff a dinode when the data has grown too big
+ * @ip: The GFS2 inode to unstuff
+ * @page: The (optional) page. This is looked up if the @page is NULL
+ *
+ * This routine unstuffs a dinode and returns it to a "normal" state such
+ * that the height can be grown in the traditional way.
+ *
+ * Returns: errno
+ */
+
+int gfs2_unstuff_dinode(struct gfs2_inode *ip, struct page *page)
+{
+	struct buffer_head *bh, *dibh;
+	struct gfs2_dinode *di;
+	u64 block = 0;
+	int isdir = gfs2_is_dir(ip);
+	int error;
+
+	down_write(&ip->i_rw_mutex);
+
+	error = gfs2_meta_inode_buffer(ip, &dibh);
+	if (error)
+		goto out;
+
+	if (i_size_read(&ip->i_inode)) {
+		/* Get a free block, fill it with the stuffed data,
+		   and write it out to disk */
+
+		unsigned int n = 1;
+		error = gfs2_alloc_blocks(ip, &block, &n, 0, NULL);
+		if (error)
+			goto out_brelse;
+		if (isdir) {
+			gfs2_trans_add_unrevoke(GFS2_SB(&ip->i_inode), block, 1);
+			error = gfs2_dir_get_new_buffer(ip, block, &bh);
+			if (error)
+				goto out_brelse;
+			gfs2_buffer_copy_tail(bh, sizeof(struct gfs2_meta_header),
+					      dibh, sizeof(struct gfs2_dinode));
+			brelse(bh);
+		} else {
+			error = gfs2_unstuffer_page(ip, dibh, block, page);
+			if (error)
+				goto out_brelse;
+		}
+	}
+
+	/*  Set up the pointer to the new block  */
+
+	gfs2_trans_add_meta(ip->i_gl, dibh);
+	di = (struct gfs2_dinode *)dibh->b_data;
+	gfs2_buffer_clear_tail(dibh, sizeof(struct gfs2_dinode));
+
+	if (i_size_read(&ip->i_inode)) {
+		*(__be64 *)(di + 1) = cpu_to_be64(block);
+		gfs2_add_inode_blocks(&ip->i_inode, 1);
+		di->di_blocks = cpu_to_be64(gfs2_get_inode_blocks(&ip->i_inode));
+	}
+
+	ip->i_height = 1;
+	di->di_height = cpu_to_be16(1);
+
+out_brelse:
+	brelse(dibh);
+out:
+	up_write(&ip->i_rw_mutex);
+	return error;
+}
+
+
+/**
+ * find_metapath - Find path through the metadata tree
+ * @sdp: The superblock
+ * @block: The disk block to look up
+ * @mp: The metapath to return the result in
+ * @height: The pre-calculated height of the metadata tree
+ *
+ *   This routine returns a struct metapath structure that defines a path
+ *   through the metadata of inode "ip" to get to block "block".
+ *
+ *   Example:
+ *   Given:  "ip" is a height 3 file, "offset" is 101342453, and this is a
+ *   filesystem with a blocksize of 4096.
+ *
+ *   find_metapath() would return a struct metapath structure set to:
+ *   mp_fheight = 3, mp_list[0] = 0, mp_list[1] = 48, and mp_list[2] = 165.
+ *
+ *   That means that in order to get to the block containing the byte at
+ *   offset 101342453, we would load the indirect block pointed to by pointer
+ *   0 in the dinode.  We would then load the indirect block pointed to by
+ *   pointer 48 in that indirect block.  We would then load the data block
+ *   pointed to by pointer 165 in that indirect block.
+ *
+ *             ----------------------------------------
+ *             | Dinode |                             |
+ *             |        |                            4|
+ *             |        |0 1 2 3 4 5                 9|
+ *             |        |                            6|
+ *             ----------------------------------------
+ *                       |
+ *                       |
+ *                       V
+ *             ----------------------------------------
+ *             | Indirect Block                       |
+ *             |                                     5|
+ *             |            4 4 4 4 4 5 5            1|
+ *             |0           5 6 7 8 9 0 1            2|
+ *             ----------------------------------------
+ *                                |
+ *                                |
+ *                                V
+ *             ----------------------------------------
+ *             | Indirect Block                       |
+ *             |                         1 1 1 1 1   5|
+ *             |                         6 6 6 6 6   1|
+ *             |0                        3 4 5 6 7   2|
+ *             ----------------------------------------
+ *                                           |
+ *                                           |
+ *                                           V
+ *             ----------------------------------------
+ *             | Data block containing offset         |
+ *             |            101342453                 |
+ *             |                                      |
+ *             |                                      |
+ *             ----------------------------------------
+ *
+ */
+
+static void find_metapath(const struct gfs2_sbd *sdp, u64 block,
+			  struct metapath *mp, unsigned int height)
+{
+	unsigned int i;
+
+	mp->mp_fheight = height;
+	for (i = height; i--;)
+		mp->mp_list[i] = do_div(block, sdp->sd_inptrs);
+}
+
+static inline unsigned int metapath_branch_start(const struct metapath *mp)
+{
+	if (mp->mp_list[0] == 0)
+		return 2;
+	return 1;
+}
+
+/**
+ * metaptr1 - Return the first possible metadata pointer in a metapath buffer
+ * @height: The metadata height (0 = dinode)
+ * @mp: The metapath
+ */
+static inline __be64 *metaptr1(unsigned int height, const struct metapath *mp)
+{
+	struct buffer_head *bh = mp->mp_bh[height];
+	if (height == 0)
+		return ((__be64 *)(bh->b_data + sizeof(struct gfs2_dinode)));
+	return ((__be64 *)(bh->b_data + sizeof(struct gfs2_meta_header)));
+}
+
+/**
+ * metapointer - Return pointer to start of metadata in a buffer
+ * @height: The metadata height (0 = dinode)
+ * @mp: The metapath
+ *
+ * Return a pointer to the block number of the next height of the metadata
+ * tree given a buffer containing the pointer to the current height of the
+ * metadata tree.
+ */
+
+static inline __be64 *metapointer(unsigned int height, const struct metapath *mp)
+{
+	__be64 *p = metaptr1(height, mp);
+	return p + mp->mp_list[height];
+}
+
+static inline const __be64 *metaend(unsigned int height, const struct metapath *mp)
+{
+	const struct buffer_head *bh = mp->mp_bh[height];
+	return (const __be64 *)(bh->b_data + bh->b_size);
+}
+
+static void clone_metapath(struct metapath *clone, struct metapath *mp)
+{
+	unsigned int hgt;
+
+	*clone = *mp;
+	for (hgt = 0; hgt < mp->mp_aheight; hgt++)
+		get_bh(clone->mp_bh[hgt]);
+}
+
+static void gfs2_metapath_ra(struct gfs2_glock *gl, __be64 *start, __be64 *end)
+{
+	const __be64 *t;
+
+	for (t = start; t < end; t++) {
+		struct buffer_head *rabh;
+
+		if (!*t)
+			continue;
+
+		rabh = gfs2_getbuf(gl, be64_to_cpu(*t), CREATE);
+		if (trylock_buffer(rabh)) {
+			if (!buffer_uptodate(rabh)) {
+				rabh->b_end_io = end_buffer_read_sync;
+				submit_bh(REQ_OP_READ,
+					  REQ_RAHEAD | REQ_META | REQ_PRIO,
+					  rabh);
+				continue;
+			}
+			unlock_buffer(rabh);
+		}
+		brelse(rabh);
+	}
+}
+
+static int __fillup_metapath(struct gfs2_inode *ip, struct metapath *mp,
+			     unsigned int x, unsigned int h)
+{
+	for (; x < h; x++) {
+		__be64 *ptr = metapointer(x, mp);
+		u64 dblock = be64_to_cpu(*ptr);
+		int ret;
+
+		if (!dblock)
+			break;
+		ret = gfs2_meta_indirect_buffer(ip, x + 1, dblock, &mp->mp_bh[x + 1]);
+		if (ret)
+			return ret;
+	}
+	mp->mp_aheight = x + 1;
+	return 0;
+}
+
+/**
+ * lookup_metapath - Walk the metadata tree to a specific point
+ * @ip: The inode
+ * @mp: The metapath
+ *
+ * Assumes that the inode's buffer has already been looked up and
+ * hooked onto mp->mp_bh[0] and that the metapath has been initialised
+ * by find_metapath().
+ *
+ * If this function encounters part of the tree which has not been
+ * allocated, it returns the current height of the tree at the point
+ * at which it found the unallocated block. Blocks which are found are
+ * added to the mp->mp_bh[] list.
+ *
+ * Returns: error
+ */
+
+static int lookup_metapath(struct gfs2_inode *ip, struct metapath *mp)
+{
+	return __fillup_metapath(ip, mp, 0, ip->i_height - 1);
+}
+
+/**
+ * fillup_metapath - fill up buffers for the metadata path to a specific height
+ * @ip: The inode
+ * @mp: The metapath
+ * @h: The height to which it should be mapped
+ *
+ * Similar to lookup_metapath, but does lookups for a range of heights
+ *
+ * Returns: error or the number of buffers filled
+ */
+
+static int fillup_metapath(struct gfs2_inode *ip, struct metapath *mp, int h)
+{
+	unsigned int x = 0;
+	int ret;
+
+	if (h) {
+		/* find the first buffer we need to look up. */
+		for (x = h - 1; x > 0; x--) {
+			if (mp->mp_bh[x])
+				break;
+		}
+	}
+	ret = __fillup_metapath(ip, mp, x, h);
+	if (ret)
+		return ret;
+	return mp->mp_aheight - x - 1;
+}
+
+static sector_t metapath_to_block(struct gfs2_sbd *sdp, struct metapath *mp)
+{
+	sector_t factor = 1, block = 0;
+	int hgt;
+
+	for (hgt = mp->mp_fheight - 1; hgt >= 0; hgt--) {
+		if (hgt < mp->mp_aheight)
+			block += mp->mp_list[hgt] * factor;
+		factor *= sdp->sd_inptrs;
+	}
+	return block;
+}
+
+static void release_metapath(struct metapath *mp)
+{
+	int i;
+
+	for (i = 0; i < GFS2_MAX_META_HEIGHT; i++) {
+		if (mp->mp_bh[i] == NULL)
+			break;
+		brelse(mp->mp_bh[i]);
+		mp->mp_bh[i] = NULL;
+	}
+}
+
+/**
+ * gfs2_extent_length - Returns length of an extent of blocks
+ * @bh: The metadata block
+ * @ptr: Current position in @bh
+ * @limit: Max extent length to return
+ * @eob: Set to 1 if we hit "end of block"
+ *
+ * Returns: The length of the extent (minimum of one block)
+ */
+
+static inline unsigned int gfs2_extent_length(struct buffer_head *bh, __be64 *ptr, size_t limit, int *eob)
+{
+	const __be64 *end = (__be64 *)(bh->b_data + bh->b_size);
+	const __be64 *first = ptr;
+	u64 d = be64_to_cpu(*ptr);
+
+	*eob = 0;
+	do {
+		ptr++;
+		if (ptr >= end)
+			break;
+		d++;
+	} while(be64_to_cpu(*ptr) == d);
+	if (ptr >= end)
+		*eob = 1;
+	return ptr - first;
+}
+
+enum walker_status { WALK_STOP, WALK_FOLLOW, WALK_CONTINUE };
+
+/*
+ * gfs2_metadata_walker - walk an indirect block
+ * @mp: Metapath to indirect block
+ * @ptrs: Number of pointers to look at
+ *
+ * When returning WALK_FOLLOW, the walker must update @mp to point at the right
+ * indirect block to follow.
+ */
+typedef enum walker_status (*gfs2_metadata_walker)(struct metapath *mp,
+						   unsigned int ptrs);
+
+/*
+ * gfs2_walk_metadata - walk a tree of indirect blocks
+ * @inode: The inode
+ * @mp: Starting point of walk
+ * @max_len: Maximum number of blocks to walk
+ * @walker: Called during the walk
+ *
+ * Returns 1 if the walk was stopped by @walker, 0 if we went past @max_len or
+ * past the end of metadata, and a negative error code otherwise.
+ */
+
+static int gfs2_walk_metadata(struct inode *inode, struct metapath *mp,
+		u64 max_len, gfs2_metadata_walker walker)
+{
+	struct gfs2_inode *ip = GFS2_I(inode);
+	struct gfs2_sbd *sdp = GFS2_SB(inode);
+	u64 factor = 1;
+	unsigned int hgt;
+	int ret;
+
+	/*
+	 * The walk starts in the lowest allocated indirect block, which may be
+	 * before the position indicated by @mp.  Adjust @max_len accordingly
+	 * to avoid a short walk.
+	 */
+	for (hgt = mp->mp_fheight - 1; hgt >= mp->mp_aheight; hgt--) {
+		max_len += mp->mp_list[hgt] * factor;
+		mp->mp_list[hgt] = 0;
+		factor *= sdp->sd_inptrs;
+	}
+
+	for (;;) {
+		u16 start = mp->mp_list[hgt];
+		enum walker_status status;
+		unsigned int ptrs;
+		u64 len;
+
+		/* Walk indirect block. */
+		ptrs = (hgt >= 1 ? sdp->sd_inptrs : sdp->sd_diptrs) - start;
+		len = ptrs * factor;
+		if (len > max_len)
+			ptrs = DIV_ROUND_UP_ULL(max_len, factor);
+		status = walker(mp, ptrs);
+		switch (status) {
+		case WALK_STOP:
+			return 1;
+		case WALK_FOLLOW:
+			BUG_ON(mp->mp_aheight == mp->mp_fheight);
+			ptrs = mp->mp_list[hgt] - start;
+			len = ptrs * factor;
+			break;
+		case WALK_CONTINUE:
+			break;
+		}
+		if (len >= max_len)
+			break;
+		max_len -= len;
+		if (status == WALK_FOLLOW)
+			goto fill_up_metapath;
+
+lower_metapath:
+		/* Decrease height of metapath. */
+		brelse(mp->mp_bh[hgt]);
+		mp->mp_bh[hgt] = NULL;
+		mp->mp_list[hgt] = 0;
+		if (!hgt)
+			break;
+		hgt--;
+		factor *= sdp->sd_inptrs;
+
+		/* Advance in metadata tree. */
+		(mp->mp_list[hgt])++;
+		if (hgt) {
+			if (mp->mp_list[hgt] >= sdp->sd_inptrs)
+				goto lower_metapath;
+		} else {
+			if (mp->mp_list[hgt] >= sdp->sd_diptrs)
+				break;
+		}
+
+fill_up_metapath:
+		/* Increase height of metapath. */
+		ret = fillup_metapath(ip, mp, ip->i_height - 1);
+		if (ret < 0)
+			return ret;
+		hgt += ret;
+		for (; ret; ret--)
+			do_div(factor, sdp->sd_inptrs);
+		mp->mp_aheight = hgt + 1;
+	}
+	return 0;
+}
+
+static enum walker_status gfs2_hole_walker(struct metapath *mp,
+					   unsigned int ptrs)
+{
+	const __be64 *start, *ptr, *end;
+	unsigned int hgt;
+
+	hgt = mp->mp_aheight - 1;
+	start = metapointer(hgt, mp);
+	end = start + ptrs;
+
+	for (ptr = start; ptr < end; ptr++) {
+		if (*ptr) {
+			mp->mp_list[hgt] += ptr - start;
+			if (mp->mp_aheight == mp->mp_fheight)
+				return WALK_STOP;
+			return WALK_FOLLOW;
+		}
+	}
+	return WALK_CONTINUE;
+}
+
+/**
+ * gfs2_hole_size - figure out the size of a hole
+ * @inode: The inode
+ * @lblock: The logical starting block number
+ * @len: How far to look (in blocks)
+ * @mp: The metapath at lblock
+ * @iomap: The iomap to store the hole size in
+ *
+ * This function modifies @mp.
+ *
+ * Returns: errno on error
+ */
+static int gfs2_hole_size(struct inode *inode, sector_t lblock, u64 len,
+			  struct metapath *mp, struct iomap *iomap)
+{
+	struct metapath clone;
+	u64 hole_size;
+	int ret;
+
+	clone_metapath(&clone, mp);
+	ret = gfs2_walk_metadata(inode, &clone, len, gfs2_hole_walker);
+	if (ret < 0)
+		goto out;
+
+	if (ret == 1)
+		hole_size = metapath_to_block(GFS2_SB(inode), &clone) - lblock;
+	else
+		hole_size = len;
+	iomap->length = hole_size << inode->i_blkbits;
+	ret = 0;
+
+out:
+	release_metapath(&clone);
+	return ret;
+}
+
+static inline __be64 *gfs2_indirect_init(struct metapath *mp,
+					 struct gfs2_glock *gl, unsigned int i,
+					 unsigned offset, u64 bn)
+{
+	__be64 *ptr = (__be64 *)(mp->mp_bh[i - 1]->b_data +
+		       ((i > 1) ? sizeof(struct gfs2_meta_header) :
+				 sizeof(struct gfs2_dinode)));
+	BUG_ON(i < 1);
+	BUG_ON(mp->mp_bh[i] != NULL);
+	mp->mp_bh[i] = gfs2_meta_new(gl, bn);
+	gfs2_trans_add_meta(gl, mp->mp_bh[i]);
+	gfs2_metatype_set(mp->mp_bh[i], GFS2_METATYPE_IN, GFS2_FORMAT_IN);
+	gfs2_buffer_clear_tail(mp->mp_bh[i], sizeof(struct gfs2_meta_header));
+	ptr += offset;
+	*ptr = cpu_to_be64(bn);
+	return ptr;
+}
+
+enum alloc_state {
+	ALLOC_DATA = 0,
+	ALLOC_GROW_DEPTH = 1,
+	ALLOC_GROW_HEIGHT = 2,
+	/* ALLOC_UNSTUFF = 3,   TBD and rather complicated */
+};
+
+/**
+ * gfs2_iomap_alloc - Build a metadata tree of the requested height
+ * @inode: The GFS2 inode
+ * @iomap: The iomap structure
+ * @flags: iomap flags
+ * @mp: The metapath, with proper height information calculated
+ *
+ * In this routine we may have to alloc:
+ *   i) Indirect blocks to grow the metadata tree height
+ *  ii) Indirect blocks to fill in lower part of the metadata tree
+ * iii) Data blocks
+ *
+ * This function is called after gfs2_iomap_get, which works out the
+ * total number of blocks which we need via gfs2_alloc_size.
+ *
+ * We then do the actual allocation asking for an extent at a time (if
+ * enough contiguous free blocks are available, there will only be one
+ * allocation request per call) and uses the state machine to initialise
+ * the blocks in order.
+ *
+ * Right now, this function will allocate at most one indirect block
+ * worth of data -- with a default block size of 4K, that's slightly
+ * less than 2M.  If this limitation is ever removed to allow huge
+ * allocations, we would probably still want to limit the iomap size we
+ * return to avoid stalling other tasks during huge writes; the next
+ * iomap iteration would then find the blocks already allocated.
+ *
+ * Returns: errno on error
+ */
+
+static int gfs2_iomap_alloc(struct inode *inode, struct iomap *iomap,
+			    unsigned flags, struct metapath *mp)
+{
+	struct gfs2_inode *ip = GFS2_I(inode);
+	struct gfs2_sbd *sdp = GFS2_SB(inode);
+	struct buffer_head *dibh = mp->mp_bh[0];
+	u64 bn;
+	unsigned n, i, blks, alloced = 0, iblks = 0, branch_start = 0;
+	size_t dblks = iomap->length >> inode->i_blkbits;
+	const unsigned end_of_metadata = mp->mp_fheight - 1;
+	int ret;
+	enum alloc_state state;
+	__be64 *ptr;
+	__be64 zero_bn = 0;
+
+	BUG_ON(mp->mp_aheight < 1);
+	BUG_ON(dibh == NULL);
+	BUG_ON(dblks < 1);
+
+	gfs2_trans_add_meta(ip->i_gl, dibh);
+
+	down_write(&ip->i_rw_mutex);
+
+	if (mp->mp_fheight == mp->mp_aheight) {
+		/* Bottom indirect block exists */
+		state = ALLOC_DATA;
+	} else {
+		/* Need to allocate indirect blocks */
+		if (mp->mp_fheight == ip->i_height) {
+			/* Writing into existing tree, extend tree down */
+			iblks = mp->mp_fheight - mp->mp_aheight;
+			state = ALLOC_GROW_DEPTH;
+		} else {
+			/* Building up tree height */
+			state = ALLOC_GROW_HEIGHT;
+			iblks = mp->mp_fheight - ip->i_height;
+			branch_start = metapath_branch_start(mp);
+			iblks += (mp->mp_fheight - branch_start);
+		}
+	}
+
+	/* start of the second part of the function (state machine) */
+
+	blks = dblks + iblks;
+	i = mp->mp_aheight;
+	do {
+		n = blks - alloced;
+		ret = gfs2_alloc_blocks(ip, &bn, &n, 0, NULL);
+		if (ret)
+			goto out;
+		alloced += n;
+		if (state != ALLOC_DATA || gfs2_is_jdata(ip))
+			gfs2_trans_add_unrevoke(sdp, bn, n);
+		switch (state) {
+		/* Growing height of tree */
+		case ALLOC_GROW_HEIGHT:
+			if (i == 1) {
+				ptr = (__be64 *)(dibh->b_data +
+						 sizeof(struct gfs2_dinode));
+				zero_bn = *ptr;
+			}
+			for (; i - 1 < mp->mp_fheight - ip->i_height && n > 0;
+			     i++, n--)
+				gfs2_indirect_init(mp, ip->i_gl, i, 0, bn++);
+			if (i - 1 == mp->mp_fheight - ip->i_height) {
+				i--;
+				gfs2_buffer_copy_tail(mp->mp_bh[i],
+						sizeof(struct gfs2_meta_header),
+						dibh, sizeof(struct gfs2_dinode));
+				gfs2_buffer_clear_tail(dibh,
+						sizeof(struct gfs2_dinode) +
+						sizeof(__be64));
+				ptr = (__be64 *)(mp->mp_bh[i]->b_data +
+					sizeof(struct gfs2_meta_header));
+				*ptr = zero_bn;
+				state = ALLOC_GROW_DEPTH;
+				for(i = branch_start; i < mp->mp_fheight; i++) {
+					if (mp->mp_bh[i] == NULL)
+						break;
+					brelse(mp->mp_bh[i]);
+					mp->mp_bh[i] = NULL;
+				}
+				i = branch_start;
+			}
+			if (n == 0)
+				break;
+		/* Branching from existing tree */
+		case ALLOC_GROW_DEPTH:
+			if (i > 1 && i < mp->mp_fheight)
+				gfs2_trans_add_meta(ip->i_gl, mp->mp_bh[i-1]);
+			for (; i < mp->mp_fheight && n > 0; i++, n--)
+				gfs2_indirect_init(mp, ip->i_gl, i,
+						   mp->mp_list[i-1], bn++);
+			if (i == mp->mp_fheight)
+				state = ALLOC_DATA;
+			if (n == 0)
+				break;
+		/* Tree complete, adding data blocks */
+		case ALLOC_DATA:
+			BUG_ON(n > dblks);
+			BUG_ON(mp->mp_bh[end_of_metadata] == NULL);
+			gfs2_trans_add_meta(ip->i_gl, mp->mp_bh[end_of_metadata]);
+			dblks = n;
+			ptr = metapointer(end_of_metadata, mp);
+			iomap->addr = bn << inode->i_blkbits;
+			iomap->flags |= IOMAP_F_MERGED | IOMAP_F_NEW;
+			while (n-- > 0)
+				*ptr++ = cpu_to_be64(bn++);
+			break;
+		}
+	} while (iomap->addr == IOMAP_NULL_ADDR);
+
+	iomap->type = IOMAP_MAPPED;
+	iomap->length = (u64)dblks << inode->i_blkbits;
+	ip->i_height = mp->mp_fheight;
+	gfs2_add_inode_blocks(&ip->i_inode, alloced);
+	gfs2_dinode_out(ip, dibh->b_data);
+out:
+	up_write(&ip->i_rw_mutex);
+	return ret;
+}
+
+#define IOMAP_F_GFS2_BOUNDARY IOMAP_F_PRIVATE
+
+/**
+ * gfs2_alloc_size - Compute the maximum allocation size
+ * @inode: The inode
+ * @mp: The metapath
+ * @size: Requested size in blocks
+ *
+ * Compute the maximum size of the next allocation at @mp.
+ *
+ * Returns: size in blocks
+ */
+static u64 gfs2_alloc_size(struct inode *inode, struct metapath *mp, u64 size)
+{
+	struct gfs2_inode *ip = GFS2_I(inode);
+	struct gfs2_sbd *sdp = GFS2_SB(inode);
+	const __be64 *first, *ptr, *end;
+
+	/*
+	 * For writes to stuffed files, this function is called twice via
+	 * gfs2_iomap_get, before and after unstuffing. The size we return the
+	 * first time needs to be large enough to get the reservation and
+	 * allocation sizes right.  The size we return the second time must
+	 * be exact or else gfs2_iomap_alloc won't do the right thing.
+	 */
+
+	if (gfs2_is_stuffed(ip) || mp->mp_fheight != mp->mp_aheight) {
+		unsigned int maxsize = mp->mp_fheight > 1 ?
+			sdp->sd_inptrs : sdp->sd_diptrs;
+		maxsize -= mp->mp_list[mp->mp_fheight - 1];
+		if (size > maxsize)
+			size = maxsize;
+		return size;
+	}
+
+	first = metapointer(ip->i_height - 1, mp);
+	end = metaend(ip->i_height - 1, mp);
+	if (end - first > size)
+		end = first + size;
+	for (ptr = first; ptr < end; ptr++) {
+		if (*ptr)
+			break;
+	}
+	return ptr - first;
+}
+
+/**
+ * gfs2_iomap_get - Map blocks from an inode to disk blocks
+ * @inode: The inode
+ * @pos: Starting position in bytes
+ * @length: Length to map, in bytes
+ * @flags: iomap flags
+ * @iomap: The iomap structure
+ * @mp: The metapath
+ *
+ * Returns: errno
+ */
+static int gfs2_iomap_get(struct inode *inode, loff_t pos, loff_t length,
+			  unsigned flags, struct iomap *iomap,
+			  struct metapath *mp)
+{
+	struct gfs2_inode *ip = GFS2_I(inode);
+	struct gfs2_sbd *sdp = GFS2_SB(inode);
+	loff_t size = i_size_read(inode);
+	__be64 *ptr;
+	sector_t lblock;
+	sector_t lblock_stop;
+	int ret;
+	int eob;
+	u64 len;
+	struct buffer_head *dibh = NULL, *bh;
+	u8 height;
+
+	if (!length)
+		return -EINVAL;
+
+	down_read(&ip->i_rw_mutex);
+
+	ret = gfs2_meta_inode_buffer(ip, &dibh);
+	if (ret)
+		goto unlock;
+	mp->mp_bh[0] = dibh;
+
+	if (gfs2_is_stuffed(ip)) {
+		if (flags & IOMAP_WRITE) {
+			loff_t max_size = gfs2_max_stuffed_size(ip);
+
+			if (pos + length > max_size)
+				goto unstuff;
+			iomap->length = max_size;
+		} else {
+			if (pos >= size) {
+				if (flags & IOMAP_REPORT) {
+					ret = -ENOENT;
+					goto unlock;
+				} else {
+					iomap->offset = pos;
+					iomap->length = length;
+					goto hole_found;
+				}
+			}
+			iomap->length = size;
+		}
+		iomap->addr = (ip->i_no_addr << inode->i_blkbits) +
+			      sizeof(struct gfs2_dinode);
+		iomap->type = IOMAP_INLINE;
+		iomap->inline_data = dibh->b_data + sizeof(struct gfs2_dinode);
+		goto out;
+	}
+
+unstuff:
+	lblock = pos >> inode->i_blkbits;
+	iomap->offset = lblock << inode->i_blkbits;
+	lblock_stop = (pos + length - 1) >> inode->i_blkbits;
+	len = lblock_stop - lblock + 1;
+	iomap->length = len << inode->i_blkbits;
+
+	height = ip->i_height;
+	while ((lblock + 1) * sdp->sd_sb.sb_bsize > sdp->sd_heightsize[height])
+		height++;
+	find_metapath(sdp, lblock, mp, height);
+	if (height > ip->i_height || gfs2_is_stuffed(ip))
+		goto do_alloc;
+
+	ret = lookup_metapath(ip, mp);
+	if (ret)
+		goto unlock;
+
+	if (mp->mp_aheight != ip->i_height)
+		goto do_alloc;
+
+	ptr = metapointer(ip->i_height - 1, mp);
+	if (*ptr == 0)
+		goto do_alloc;
+
+	bh = mp->mp_bh[ip->i_height - 1];
+	len = gfs2_extent_length(bh, ptr, len, &eob);
+
+	iomap->addr = be64_to_cpu(*ptr) << inode->i_blkbits;
+	iomap->length = len << inode->i_blkbits;
+	iomap->type = IOMAP_MAPPED;
+	iomap->flags |= IOMAP_F_MERGED;
+	if (eob)
+		iomap->flags |= IOMAP_F_GFS2_BOUNDARY;
+
+out:
+	iomap->bdev = inode->i_sb->s_bdev;
+unlock:
+	up_read(&ip->i_rw_mutex);
+	return ret;
+
+do_alloc:
+	if (flags & IOMAP_REPORT) {
+		if (pos >= size)
+			ret = -ENOENT;
+		else if (height == ip->i_height)
+			ret = gfs2_hole_size(inode, lblock, len, mp, iomap);
+		else
+			iomap->length = size - iomap->offset;
+	} else if (flags & IOMAP_WRITE) {
+		u64 alloc_size;
+
+		if (flags & IOMAP_DIRECT)
+			goto out;  /* (see gfs2_file_direct_write) */
+
+		len = gfs2_alloc_size(inode, mp, len);
+		alloc_size = len << inode->i_blkbits;
+		if (alloc_size < iomap->length)
+			iomap->length = alloc_size;
+	} else {
+		if (pos < size && height == ip->i_height)
+			ret = gfs2_hole_size(inode, lblock, len, mp, iomap);
+	}
+hole_found:
+	iomap->addr = IOMAP_NULL_ADDR;
+	iomap->type = IOMAP_HOLE;
+	goto out;
+}
+
+static int gfs2_write_lock(struct inode *inode)
+{
+	struct gfs2_inode *ip = GFS2_I(inode);
+	struct gfs2_sbd *sdp = GFS2_SB(inode);
+	int error;
+
+	gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &ip->i_gh);
+	error = gfs2_glock_nq(&ip->i_gh);
+	if (error)
+		goto out_uninit;
+	if (&ip->i_inode == sdp->sd_rindex) {
+		struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
+
+		error = gfs2_glock_nq_init(m_ip->i_gl, LM_ST_EXCLUSIVE,
+					   GL_NOCACHE, &m_ip->i_gh);
+		if (error)
+			goto out_unlock;
+	}
+	return 0;
+
+out_unlock:
+	gfs2_glock_dq(&ip->i_gh);
+out_uninit:
+	gfs2_holder_uninit(&ip->i_gh);
+	return error;
+}
+
+static void gfs2_write_unlock(struct inode *inode)
+{
+	struct gfs2_inode *ip = GFS2_I(inode);
+	struct gfs2_sbd *sdp = GFS2_SB(inode);
+
+	if (&ip->i_inode == sdp->sd_rindex) {
+		struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
+
+		gfs2_glock_dq_uninit(&m_ip->i_gh);
+	}
+	gfs2_glock_dq_uninit(&ip->i_gh);
+}
+
+static void gfs2_iomap_journaled_page_done(struct inode *inode, loff_t pos,
+				unsigned copied, struct page *page,
+				struct iomap *iomap)
+{
+	struct gfs2_inode *ip = GFS2_I(inode);
+
+	gfs2_page_add_databufs(ip, page, offset_in_page(pos), copied);
+}
+
+static int gfs2_iomap_begin_write(struct inode *inode, loff_t pos,
+				  loff_t length, unsigned flags,
+				  struct iomap *iomap,
+				  struct metapath *mp)
+{
+	struct gfs2_inode *ip = GFS2_I(inode);
+	struct gfs2_sbd *sdp = GFS2_SB(inode);
+	unsigned int data_blocks = 0, ind_blocks = 0, rblocks;
+	bool unstuff, alloc_required;
+	int ret;
+
+	ret = gfs2_write_lock(inode);
+	if (ret)
+		return ret;
+
+	unstuff = gfs2_is_stuffed(ip) &&
+		  pos + length > gfs2_max_stuffed_size(ip);
+
+	ret = gfs2_iomap_get(inode, pos, length, flags, iomap, mp);
+	if (ret)
+		goto out_unlock;
+
+	alloc_required = unstuff || iomap->type == IOMAP_HOLE;
+
+	if (alloc_required || gfs2_is_jdata(ip))
+		gfs2_write_calc_reserv(ip, iomap->length, &data_blocks,
+				       &ind_blocks);
+
+	if (alloc_required) {
+		struct gfs2_alloc_parms ap = {
+			.target = data_blocks + ind_blocks
+		};
+
+		ret = gfs2_quota_lock_check(ip, &ap);
+		if (ret)
+			goto out_unlock;
+
+		ret = gfs2_inplace_reserve(ip, &ap);
+		if (ret)
+			goto out_qunlock;
+	}
+
+	rblocks = RES_DINODE + ind_blocks;
+	if (gfs2_is_jdata(ip))
+		rblocks += data_blocks;
+	if (ind_blocks || data_blocks)
+		rblocks += RES_STATFS + RES_QUOTA;
+	if (inode == sdp->sd_rindex)
+		rblocks += 2 * RES_STATFS;
+	if (alloc_required)
+		rblocks += gfs2_rg_blocks(ip, data_blocks + ind_blocks);
+
+	ret = gfs2_trans_begin(sdp, rblocks, iomap->length >> inode->i_blkbits);
+	if (ret)
+		goto out_trans_fail;
+
+	if (unstuff) {
+		ret = gfs2_unstuff_dinode(ip, NULL);
+		if (ret)
+			goto out_trans_end;
+		release_metapath(mp);
+		ret = gfs2_iomap_get(inode, iomap->offset, iomap->length,
+				     flags, iomap, mp);
+		if (ret)
+			goto out_trans_end;
+	}
+
+	if (iomap->type == IOMAP_HOLE) {
+		ret = gfs2_iomap_alloc(inode, iomap, flags, mp);
+		if (ret) {
+			gfs2_trans_end(sdp);
+			gfs2_inplace_release(ip);
+			punch_hole(ip, iomap->offset, iomap->length);
+			goto out_qunlock;
+		}
+	}
+	if (!gfs2_is_stuffed(ip) && gfs2_is_jdata(ip))
+		iomap->page_done = gfs2_iomap_journaled_page_done;
+	return 0;
+
+out_trans_end:
+	gfs2_trans_end(sdp);
+out_trans_fail:
+	if (alloc_required)
+		gfs2_inplace_release(ip);
+out_qunlock:
+	if (alloc_required)
+		gfs2_quota_unlock(ip);
+out_unlock:
+	gfs2_write_unlock(inode);
+	return ret;
+}
+
+static int gfs2_iomap_begin(struct inode *inode, loff_t pos, loff_t length,
+			    unsigned flags, struct iomap *iomap)
+{
+	struct gfs2_inode *ip = GFS2_I(inode);
+	struct metapath mp = { .mp_aheight = 1, };
+	int ret;
+
+	iomap->flags |= IOMAP_F_BUFFER_HEAD;
+
+	trace_gfs2_iomap_start(ip, pos, length, flags);
+	if ((flags & IOMAP_WRITE) && !(flags & IOMAP_DIRECT)) {
+		ret = gfs2_iomap_begin_write(inode, pos, length, flags, iomap, &mp);
+	} else {
+		ret = gfs2_iomap_get(inode, pos, length, flags, iomap, &mp);
+
+		/*
+		 * Silently fall back to buffered I/O for stuffed files or if
+		 * we've hot a hole (see gfs2_file_direct_write).
+		 */
+		if ((flags & IOMAP_WRITE) && (flags & IOMAP_DIRECT) &&
+		    iomap->type != IOMAP_MAPPED)
+			ret = -ENOTBLK;
+	}
+	if (!ret) {
+		get_bh(mp.mp_bh[0]);
+		iomap->private = mp.mp_bh[0];
+	}
+	release_metapath(&mp);
+	trace_gfs2_iomap_end(ip, iomap, ret);
+	return ret;
+}
+
+static int gfs2_iomap_end(struct inode *inode, loff_t pos, loff_t length,
+			  ssize_t written, unsigned flags, struct iomap *iomap)
+{
+	struct gfs2_inode *ip = GFS2_I(inode);
+	struct gfs2_sbd *sdp = GFS2_SB(inode);
+	struct gfs2_trans *tr = current->journal_info;
+	struct buffer_head *dibh = iomap->private;
+
+	if ((flags & (IOMAP_WRITE | IOMAP_DIRECT)) != IOMAP_WRITE)
+		goto out;
+
+	if (iomap->type != IOMAP_INLINE) {
+		gfs2_ordered_add_inode(ip);
+
+		if (tr->tr_num_buf_new)
+			__mark_inode_dirty(inode, I_DIRTY_DATASYNC);
+		else
+			gfs2_trans_add_meta(ip->i_gl, dibh);
+	}
+
+	if (inode == sdp->sd_rindex) {
+		adjust_fs_space(inode);
+		sdp->sd_rindex_uptodate = 0;
+	}
+
+	gfs2_trans_end(sdp);
+	gfs2_inplace_release(ip);
+
+	if (length != written && (iomap->flags & IOMAP_F_NEW)) {
+		/* Deallocate blocks that were just allocated. */
+		loff_t hstart = round_up(pos + written, i_blocksize(inode));
+		loff_t hend = iomap->offset + iomap->length;
+
+		if (hstart < hend) {
+			truncate_pagecache_range(inode, hstart, hend - 1);
+			punch_hole(ip, hstart, hend - hstart);
+		}
+	}
+
+	if (ip->i_qadata && ip->i_qadata->qa_qd_num)
+		gfs2_quota_unlock(ip);
+	gfs2_write_unlock(inode);
+
+out:
+	if (dibh)
+		brelse(dibh);
+	return 0;
+}
+
+const struct iomap_ops gfs2_iomap_ops = {
+	.iomap_begin = gfs2_iomap_begin,
+	.iomap_end = gfs2_iomap_end,
+};
+
+/**
+ * gfs2_block_map - Map one or more blocks of an inode to a disk block
+ * @inode: The inode
+ * @lblock: The logical block number
+ * @bh_map: The bh to be mapped
+ * @create: True if its ok to alloc blocks to satify the request
+ *
+ * The size of the requested mapping is defined in bh_map->b_size.
+ *
+ * Clears buffer_mapped(bh_map) and leaves bh_map->b_size unchanged
+ * when @lblock is not mapped.  Sets buffer_mapped(bh_map) and
+ * bh_map->b_size to indicate the size of the mapping when @lblock and
+ * successive blocks are mapped, up to the requested size.
+ *
+ * Sets buffer_boundary() if a read of metadata will be required
+ * before the next block can be mapped. Sets buffer_new() if new
+ * blocks were allocated.
+ *
+ * Returns: errno
+ */
+
+int gfs2_block_map(struct inode *inode, sector_t lblock,
+		   struct buffer_head *bh_map, int create)
+{
+	struct gfs2_inode *ip = GFS2_I(inode);
+	loff_t pos = (loff_t)lblock << inode->i_blkbits;
+	loff_t length = bh_map->b_size;
+	struct metapath mp = { .mp_aheight = 1, };
+	struct iomap iomap = { };
+	int ret;
+
+	clear_buffer_mapped(bh_map);
+	clear_buffer_new(bh_map);
+	clear_buffer_boundary(bh_map);
+	trace_gfs2_bmap(ip, bh_map, lblock, create, 1);
+
+	if (create) {
+		ret = gfs2_iomap_get(inode, pos, length, IOMAP_WRITE, &iomap, &mp);
+		if (!ret && iomap.type == IOMAP_HOLE)
+			ret = gfs2_iomap_alloc(inode, &iomap, IOMAP_WRITE, &mp);
+		release_metapath(&mp);
+	} else {
+		ret = gfs2_iomap_get(inode, pos, length, 0, &iomap, &mp);
+		release_metapath(&mp);
+	}
+	if (ret)
+		goto out;
+
+	if (iomap.length > bh_map->b_size) {
+		iomap.length = bh_map->b_size;
+		iomap.flags &= ~IOMAP_F_GFS2_BOUNDARY;
+	}
+	if (iomap.addr != IOMAP_NULL_ADDR)
+		map_bh(bh_map, inode->i_sb, iomap.addr >> inode->i_blkbits);
+	bh_map->b_size = iomap.length;
+	if (iomap.flags & IOMAP_F_GFS2_BOUNDARY)
+		set_buffer_boundary(bh_map);
+	if (iomap.flags & IOMAP_F_NEW)
+		set_buffer_new(bh_map);
+
+out:
+	trace_gfs2_bmap(ip, bh_map, lblock, create, ret);
+	return ret;
+}
+
+/*
+ * Deprecated: do not use in new code
+ */
+int gfs2_extent_map(struct inode *inode, u64 lblock, int *new, u64 *dblock, unsigned *extlen)
+{
+	struct buffer_head bh = { .b_state = 0, .b_blocknr = 0 };
+	int ret;
+	int create = *new;
+
+	BUG_ON(!extlen);
+	BUG_ON(!dblock);
+	BUG_ON(!new);
+
+	bh.b_size = BIT(inode->i_blkbits + (create ? 0 : 5));
+	ret = gfs2_block_map(inode, lblock, &bh, create);
+	*extlen = bh.b_size >> inode->i_blkbits;
+	*dblock = bh.b_blocknr;
+	if (buffer_new(&bh))
+		*new = 1;
+	else
+		*new = 0;
+	return ret;
+}
+
+/**
+ * gfs2_block_zero_range - Deal with zeroing out data
+ *
+ * This is partly borrowed from ext3.
+ */
+static int gfs2_block_zero_range(struct inode *inode, loff_t from,
+				 unsigned int length)
+{
+	struct address_space *mapping = inode->i_mapping;
+	struct gfs2_inode *ip = GFS2_I(inode);
+	unsigned long index = from >> PAGE_SHIFT;
+	unsigned offset = from & (PAGE_SIZE-1);
+	unsigned blocksize, iblock, pos;
+	struct buffer_head *bh;
+	struct page *page;
+	int err;
+
+	page = find_or_create_page(mapping, index, GFP_NOFS);
+	if (!page)
+		return 0;
+
+	blocksize = inode->i_sb->s_blocksize;
+	iblock = index << (PAGE_SHIFT - inode->i_sb->s_blocksize_bits);
+
+	if (!page_has_buffers(page))
+		create_empty_buffers(page, blocksize, 0);
+
+	/* Find the buffer that contains "offset" */
+	bh = page_buffers(page);
+	pos = blocksize;
+	while (offset >= pos) {
+		bh = bh->b_this_page;
+		iblock++;
+		pos += blocksize;
+	}
+
+	err = 0;
+
+	if (!buffer_mapped(bh)) {
+		gfs2_block_map(inode, iblock, bh, 0);
+		/* unmapped? It's a hole - nothing to do */
+		if (!buffer_mapped(bh))
+			goto unlock;
+	}
+
+	/* Ok, it's mapped. Make sure it's up-to-date */
+	if (PageUptodate(page))
+		set_buffer_uptodate(bh);
+
+	if (!buffer_uptodate(bh)) {
+		err = -EIO;
+		ll_rw_block(REQ_OP_READ, 0, 1, &bh);
+		wait_on_buffer(bh);
+		/* Uhhuh. Read error. Complain and punt. */
+		if (!buffer_uptodate(bh))
+			goto unlock;
+		err = 0;
+	}
+
+	if (gfs2_is_jdata(ip))
+		gfs2_trans_add_data(ip->i_gl, bh);
+	else
+		gfs2_ordered_add_inode(ip);
+
+	zero_user(page, offset, length);
+	mark_buffer_dirty(bh);
+unlock:
+	unlock_page(page);
+	put_page(page);
+	return err;
+}
+
+#define GFS2_JTRUNC_REVOKES 8192
+
+/**
+ * gfs2_journaled_truncate - Wrapper for truncate_pagecache for jdata files
+ * @inode: The inode being truncated
+ * @oldsize: The original (larger) size
+ * @newsize: The new smaller size
+ *
+ * With jdata files, we have to journal a revoke for each block which is
+ * truncated. As a result, we need to split this into separate transactions
+ * if the number of pages being truncated gets too large.
+ */
+
+static int gfs2_journaled_truncate(struct inode *inode, u64 oldsize, u64 newsize)
+{
+	struct gfs2_sbd *sdp = GFS2_SB(inode);
+	u64 max_chunk = GFS2_JTRUNC_REVOKES * sdp->sd_vfs->s_blocksize;
+	u64 chunk;
+	int error;
+
+	while (oldsize != newsize) {
+		struct gfs2_trans *tr;
+		unsigned int offs;
+
+		chunk = oldsize - newsize;
+		if (chunk > max_chunk)
+			chunk = max_chunk;
+
+		offs = oldsize & ~PAGE_MASK;
+		if (offs && chunk > PAGE_SIZE)
+			chunk = offs + ((chunk - offs) & PAGE_MASK);
+
+		truncate_pagecache(inode, oldsize - chunk);
+		oldsize -= chunk;
+
+		tr = current->journal_info;
+		if (!test_bit(TR_TOUCHED, &tr->tr_flags))
+			continue;
+
+		gfs2_trans_end(sdp);
+		error = gfs2_trans_begin(sdp, RES_DINODE, GFS2_JTRUNC_REVOKES);
+		if (error)
+			return error;
+	}
+
+	return 0;
+}
+
+static int trunc_start(struct inode *inode, u64 newsize)
+{
+	struct gfs2_inode *ip = GFS2_I(inode);
+	struct gfs2_sbd *sdp = GFS2_SB(inode);
+	struct buffer_head *dibh = NULL;
+	int journaled = gfs2_is_jdata(ip);
+	u64 oldsize = inode->i_size;
+	int error;
+
+	if (journaled)
+		error = gfs2_trans_begin(sdp, RES_DINODE + RES_JDATA, GFS2_JTRUNC_REVOKES);
+	else
+		error = gfs2_trans_begin(sdp, RES_DINODE, 0);
+	if (error)
+		return error;
+
+	error = gfs2_meta_inode_buffer(ip, &dibh);
+	if (error)
+		goto out;
+
+	gfs2_trans_add_meta(ip->i_gl, dibh);
+
+	if (gfs2_is_stuffed(ip)) {
+		gfs2_buffer_clear_tail(dibh, sizeof(struct gfs2_dinode) + newsize);
+	} else {
+		unsigned int blocksize = i_blocksize(inode);
+		unsigned int offs = newsize & (blocksize - 1);
+		if (offs) {
+			error = gfs2_block_zero_range(inode, newsize,
+						      blocksize - offs);
+			if (error)
+				goto out;
+		}
+		ip->i_diskflags |= GFS2_DIF_TRUNC_IN_PROG;
+	}
+
+	i_size_write(inode, newsize);
+	ip->i_inode.i_mtime = ip->i_inode.i_ctime = current_time(&ip->i_inode);
+	gfs2_dinode_out(ip, dibh->b_data);
+
+	if (journaled)
+		error = gfs2_journaled_truncate(inode, oldsize, newsize);
+	else
+		truncate_pagecache(inode, newsize);
+
+out:
+	brelse(dibh);
+	if (current->journal_info)
+		gfs2_trans_end(sdp);
+	return error;
+}
+
+int gfs2_iomap_get_alloc(struct inode *inode, loff_t pos, loff_t length,
+			 struct iomap *iomap)
+{
+	struct metapath mp = { .mp_aheight = 1, };
+	int ret;
+
+	ret = gfs2_iomap_get(inode, pos, length, IOMAP_WRITE, iomap, &mp);
+	if (!ret && iomap->type == IOMAP_HOLE)
+		ret = gfs2_iomap_alloc(inode, iomap, IOMAP_WRITE, &mp);
+	release_metapath(&mp);
+	return ret;
+}
+
+/**
+ * sweep_bh_for_rgrps - find an rgrp in a meta buffer and free blocks therein
+ * @ip: inode
+ * @rg_gh: holder of resource group glock
+ * @bh: buffer head to sweep
+ * @start: starting point in bh
+ * @end: end point in bh
+ * @meta: true if bh points to metadata (rather than data)
+ * @btotal: place to keep count of total blocks freed
+ *
+ * We sweep a metadata buffer (provided by the metapath) for blocks we need to
+ * free, and free them all. However, we do it one rgrp at a time. If this
+ * block has references to multiple rgrps, we break it into individual
+ * transactions. This allows other processes to use the rgrps while we're
+ * focused on a single one, for better concurrency / performance.
+ * At every transaction boundary, we rewrite the inode into the journal.
+ * That way the bitmaps are kept consistent with the inode and we can recover
+ * if we're interrupted by power-outages.
+ *
+ * Returns: 0, or return code if an error occurred.
+ *          *btotal has the total number of blocks freed
+ */
+static int sweep_bh_for_rgrps(struct gfs2_inode *ip, struct gfs2_holder *rd_gh,
+			      struct buffer_head *bh, __be64 *start, __be64 *end,
+			      bool meta, u32 *btotal)
+{
+	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
+	struct gfs2_rgrpd *rgd;
+	struct gfs2_trans *tr;
+	__be64 *p;
+	int blks_outside_rgrp;
+	u64 bn, bstart, isize_blks;
+	s64 blen; /* needs to be s64 or gfs2_add_inode_blocks breaks */
+	int ret = 0;
+	bool buf_in_tr = false; /* buffer was added to transaction */
+
+more_rgrps:
+	rgd = NULL;
+	if (gfs2_holder_initialized(rd_gh)) {
+		rgd = gfs2_glock2rgrp(rd_gh->gh_gl);
+		gfs2_assert_withdraw(sdp,
+			     gfs2_glock_is_locked_by_me(rd_gh->gh_gl));
+	}
+	blks_outside_rgrp = 0;
+	bstart = 0;
+	blen = 0;
+
+	for (p = start; p < end; p++) {
+		if (!*p)
+			continue;
+		bn = be64_to_cpu(*p);
+
+		if (rgd) {
+			if (!rgrp_contains_block(rgd, bn)) {
+				blks_outside_rgrp++;
+				continue;
+			}
+		} else {
+			rgd = gfs2_blk2rgrpd(sdp, bn, true);
+			if (unlikely(!rgd)) {
+				ret = -EIO;
+				goto out;
+			}
+			ret = gfs2_glock_nq_init(rgd->rd_gl, LM_ST_EXCLUSIVE,
+						 0, rd_gh);
+			if (ret)
+				goto out;
+
+			/* Must be done with the rgrp glock held: */
+			if (gfs2_rs_active(&ip->i_res) &&
+			    rgd == ip->i_res.rs_rbm.rgd)
+				gfs2_rs_deltree(&ip->i_res);
+		}
+
+		/* The size of our transactions will be unknown until we
+		   actually process all the metadata blocks that relate to
+		   the rgrp. So we estimate. We know it can't be more than
+		   the dinode's i_blocks and we don't want to exceed the
+		   journal flush threshold, sd_log_thresh2. */
+		if (current->journal_info == NULL) {
+			unsigned int jblocks_rqsted, revokes;
+
+			jblocks_rqsted = rgd->rd_length + RES_DINODE +
+				RES_INDIRECT;
+			isize_blks = gfs2_get_inode_blocks(&ip->i_inode);
+			if (isize_blks > atomic_read(&sdp->sd_log_thresh2))
+				jblocks_rqsted +=
+					atomic_read(&sdp->sd_log_thresh2);
+			else
+				jblocks_rqsted += isize_blks;
+			revokes = jblocks_rqsted;
+			if (meta)
+				revokes += end - start;
+			else if (ip->i_depth)
+				revokes += sdp->sd_inptrs;
+			ret = gfs2_trans_begin(sdp, jblocks_rqsted, revokes);
+			if (ret)
+				goto out_unlock;
+			down_write(&ip->i_rw_mutex);
+		}
+		/* check if we will exceed the transaction blocks requested */
+		tr = current->journal_info;
+		if (tr->tr_num_buf_new + RES_STATFS +
+		    RES_QUOTA >= atomic_read(&sdp->sd_log_thresh2)) {
+			/* We set blks_outside_rgrp to ensure the loop will
+			   be repeated for the same rgrp, but with a new
+			   transaction. */
+			blks_outside_rgrp++;
+			/* This next part is tricky. If the buffer was added
+			   to the transaction, we've already set some block
+			   pointers to 0, so we better follow through and free
+			   them, or we will introduce corruption (so break).
+			   This may be impossible, or at least rare, but I
+			   decided to cover the case regardless.
+
+			   If the buffer was not added to the transaction
+			   (this call), doing so would exceed our transaction
+			   size, so we need to end the transaction and start a
+			   new one (so goto). */
+
+			if (buf_in_tr)
+				break;
+			goto out_unlock;
+		}
+
+		gfs2_trans_add_meta(ip->i_gl, bh);
+		buf_in_tr = true;
+		*p = 0;
+		if (bstart + blen == bn) {
+			blen++;
+			continue;
+		}
+		if (bstart) {
+			__gfs2_free_blocks(ip, bstart, (u32)blen, meta);
+			(*btotal) += blen;
+			gfs2_add_inode_blocks(&ip->i_inode, -blen);
+		}
+		bstart = bn;
+		blen = 1;
+	}
+	if (bstart) {
+		__gfs2_free_blocks(ip, bstart, (u32)blen, meta);
+		(*btotal) += blen;
+		gfs2_add_inode_blocks(&ip->i_inode, -blen);
+	}
+out_unlock:
+	if (!ret && blks_outside_rgrp) { /* If buffer still has non-zero blocks
+					    outside the rgrp we just processed,
+					    do it all over again. */
+		if (current->journal_info) {
+			struct buffer_head *dibh;
+
+			ret = gfs2_meta_inode_buffer(ip, &dibh);
+			if (ret)
+				goto out;
+
+			/* Every transaction boundary, we rewrite the dinode
+			   to keep its di_blocks current in case of failure. */
+			ip->i_inode.i_mtime = ip->i_inode.i_ctime =
+				current_time(&ip->i_inode);
+			gfs2_trans_add_meta(ip->i_gl, dibh);
+			gfs2_dinode_out(ip, dibh->b_data);
+			brelse(dibh);
+			up_write(&ip->i_rw_mutex);
+			gfs2_trans_end(sdp);
+			buf_in_tr = false;
+		}
+		gfs2_glock_dq_uninit(rd_gh);
+		cond_resched();
+		goto more_rgrps;
+	}
+out:
+	return ret;
+}
+
+static bool mp_eq_to_hgt(struct metapath *mp, __u16 *list, unsigned int h)
+{
+	if (memcmp(mp->mp_list, list, h * sizeof(mp->mp_list[0])))
+		return false;
+	return true;
+}
+
+/**
+ * find_nonnull_ptr - find a non-null pointer given a metapath and height
+ * @mp: starting metapath
+ * @h: desired height to search
+ *
+ * Assumes the metapath is valid (with buffers) out to height h.
+ * Returns: true if a non-null pointer was found in the metapath buffer
+ *          false if all remaining pointers are NULL in the buffer
+ */
+static bool find_nonnull_ptr(struct gfs2_sbd *sdp, struct metapath *mp,
+			     unsigned int h,
+			     __u16 *end_list, unsigned int end_aligned)
+{
+	struct buffer_head *bh = mp->mp_bh[h];
+	__be64 *first, *ptr, *end;
+
+	first = metaptr1(h, mp);
+	ptr = first + mp->mp_list[h];
+	end = (__be64 *)(bh->b_data + bh->b_size);
+	if (end_list && mp_eq_to_hgt(mp, end_list, h)) {
+		bool keep_end = h < end_aligned;
+		end = first + end_list[h] + keep_end;
+	}
+
+	while (ptr < end) {
+		if (*ptr) { /* if we have a non-null pointer */
+			mp->mp_list[h] = ptr - first;
+			h++;
+			if (h < GFS2_MAX_META_HEIGHT)
+				mp->mp_list[h] = 0;
+			return true;
+		}
+		ptr++;
+	}
+	return false;
+}
+
+enum dealloc_states {
+	DEALLOC_MP_FULL = 0,    /* Strip a metapath with all buffers read in */
+	DEALLOC_MP_LOWER = 1,   /* lower the metapath strip height */
+	DEALLOC_FILL_MP = 2,  /* Fill in the metapath to the given height. */
+	DEALLOC_DONE = 3,       /* process complete */
+};
+
+static inline void
+metapointer_range(struct metapath *mp, int height,
+		  __u16 *start_list, unsigned int start_aligned,
+		  __u16 *end_list, unsigned int end_aligned,
+		  __be64 **start, __be64 **end)
+{
+	struct buffer_head *bh = mp->mp_bh[height];
+	__be64 *first;
+
+	first = metaptr1(height, mp);
+	*start = first;
+	if (mp_eq_to_hgt(mp, start_list, height)) {
+		bool keep_start = height < start_aligned;
+		*start = first + start_list[height] + keep_start;
+	}
+	*end = (__be64 *)(bh->b_data + bh->b_size);
+	if (end_list && mp_eq_to_hgt(mp, end_list, height)) {
+		bool keep_end = height < end_aligned;
+		*end = first + end_list[height] + keep_end;
+	}
+}
+
+static inline bool walk_done(struct gfs2_sbd *sdp,
+			     struct metapath *mp, int height,
+			     __u16 *end_list, unsigned int end_aligned)
+{
+	__u16 end;
+
+	if (end_list) {
+		bool keep_end = height < end_aligned;
+		if (!mp_eq_to_hgt(mp, end_list, height))
+			return false;
+		end = end_list[height] + keep_end;
+	} else
+		end = (height > 0) ? sdp->sd_inptrs : sdp->sd_diptrs;
+	return mp->mp_list[height] >= end;
+}
+
+/**
+ * punch_hole - deallocate blocks in a file
+ * @ip: inode to truncate
+ * @offset: the start of the hole
+ * @length: the size of the hole (or 0 for truncate)
+ *
+ * Punch a hole into a file or truncate a file at a given position.  This
+ * function operates in whole blocks (@offset and @length are rounded
+ * accordingly); partially filled blocks must be cleared otherwise.
+ *
+ * This function works from the bottom up, and from the right to the left. In
+ * other words, it strips off the highest layer (data) before stripping any of
+ * the metadata. Doing it this way is best in case the operation is interrupted
+ * by power failure, etc.  The dinode is rewritten in every transaction to
+ * guarantee integrity.
+ */
+static int punch_hole(struct gfs2_inode *ip, u64 offset, u64 length)
+{
+	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
+	u64 maxsize = sdp->sd_heightsize[ip->i_height];
+	struct metapath mp = {};
+	struct buffer_head *dibh, *bh;
+	struct gfs2_holder rd_gh;
+	unsigned int bsize_shift = sdp->sd_sb.sb_bsize_shift;
+	u64 lblock = (offset + (1 << bsize_shift) - 1) >> bsize_shift;
+	__u16 start_list[GFS2_MAX_META_HEIGHT];
+	__u16 __end_list[GFS2_MAX_META_HEIGHT], *end_list = NULL;
+	unsigned int start_aligned, uninitialized_var(end_aligned);
+	unsigned int strip_h = ip->i_height - 1;
+	u32 btotal = 0;
+	int ret, state;
+	int mp_h; /* metapath buffers are read in to this height */
+	u64 prev_bnr = 0;
+	__be64 *start, *end;
+
+	if (offset >= maxsize) {
+		/*
+		 * The starting point lies beyond the allocated meta-data;
+		 * there are no blocks do deallocate.
+		 */
+		return 0;
+	}
+
+	/*
+	 * The start position of the hole is defined by lblock, start_list, and
+	 * start_aligned.  The end position of the hole is defined by lend,
+	 * end_list, and end_aligned.
+	 *
+	 * start_aligned and end_aligned define down to which height the start
+	 * and end positions are aligned to the metadata tree (i.e., the
+	 * position is a multiple of the metadata granularity at the height
+	 * above).  This determines at which heights additional meta pointers
+	 * needs to be preserved for the remaining data.
+	 */
+
+	if (length) {
+		u64 end_offset = offset + length;
+		u64 lend;
+
+		/*
+		 * Clip the end at the maximum file size for the given height:
+		 * that's how far the metadata goes; files bigger than that
+		 * will have additional layers of indirection.
+		 */
+		if (end_offset > maxsize)
+			end_offset = maxsize;
+		lend = end_offset >> bsize_shift;
+
+		if (lblock >= lend)
+			return 0;
+
+		find_metapath(sdp, lend, &mp, ip->i_height);
+		end_list = __end_list;
+		memcpy(end_list, mp.mp_list, sizeof(mp.mp_list));
+
+		for (mp_h = ip->i_height - 1; mp_h > 0; mp_h--) {
+			if (end_list[mp_h])
+				break;
+		}
+		end_aligned = mp_h;
+	}
+
+	find_metapath(sdp, lblock, &mp, ip->i_height);
+	memcpy(start_list, mp.mp_list, sizeof(start_list));
+
+	for (mp_h = ip->i_height - 1; mp_h > 0; mp_h--) {
+		if (start_list[mp_h])
+			break;
+	}
+	start_aligned = mp_h;
+
+	ret = gfs2_meta_inode_buffer(ip, &dibh);
+	if (ret)
+		return ret;
+
+	mp.mp_bh[0] = dibh;
+	ret = lookup_metapath(ip, &mp);
+	if (ret)
+		goto out_metapath;
+
+	/* issue read-ahead on metadata */
+	for (mp_h = 0; mp_h < mp.mp_aheight - 1; mp_h++) {
+		metapointer_range(&mp, mp_h, start_list, start_aligned,
+				  end_list, end_aligned, &start, &end);
+		gfs2_metapath_ra(ip->i_gl, start, end);
+	}
+
+	if (mp.mp_aheight == ip->i_height)
+		state = DEALLOC_MP_FULL; /* We have a complete metapath */
+	else
+		state = DEALLOC_FILL_MP; /* deal with partial metapath */
+
+	ret = gfs2_rindex_update(sdp);
+	if (ret)
+		goto out_metapath;
+
+	ret = gfs2_quota_hold(ip, NO_UID_QUOTA_CHANGE, NO_GID_QUOTA_CHANGE);
+	if (ret)
+		goto out_metapath;
+	gfs2_holder_mark_uninitialized(&rd_gh);
+
+	mp_h = strip_h;
+
+	while (state != DEALLOC_DONE) {
+		switch (state) {
+		/* Truncate a full metapath at the given strip height.
+		 * Note that strip_h == mp_h in order to be in this state. */
+		case DEALLOC_MP_FULL:
+			bh = mp.mp_bh[mp_h];
+			gfs2_assert_withdraw(sdp, bh);
+			if (gfs2_assert_withdraw(sdp,
+						 prev_bnr != bh->b_blocknr)) {
+				printk(KERN_EMERG "GFS2: fsid=%s:inode %llu, "
+				       "block:%llu, i_h:%u, s_h:%u, mp_h:%u\n",
+				       sdp->sd_fsname,
+				       (unsigned long long)ip->i_no_addr,
+				       prev_bnr, ip->i_height, strip_h, mp_h);
+			}
+			prev_bnr = bh->b_blocknr;
+
+			if (gfs2_metatype_check(sdp, bh,
+						(mp_h ? GFS2_METATYPE_IN :
+							GFS2_METATYPE_DI))) {
+				ret = -EIO;
+				goto out;
+			}
+
+			/*
+			 * Below, passing end_aligned as 0 gives us the
+			 * metapointer range excluding the end point: the end
+			 * point is the first metapath we must not deallocate!
+			 */
+
+			metapointer_range(&mp, mp_h, start_list, start_aligned,
+					  end_list, 0 /* end_aligned */,
+					  &start, &end);
+			ret = sweep_bh_for_rgrps(ip, &rd_gh, mp.mp_bh[mp_h],
+						 start, end,
+						 mp_h != ip->i_height - 1,
+						 &btotal);
+
+			/* If we hit an error or just swept dinode buffer,
+			   just exit. */
+			if (ret || !mp_h) {
+				state = DEALLOC_DONE;
+				break;
+			}
+			state = DEALLOC_MP_LOWER;
+			break;
+
+		/* lower the metapath strip height */
+		case DEALLOC_MP_LOWER:
+			/* We're done with the current buffer, so release it,
+			   unless it's the dinode buffer. Then back up to the
+			   previous pointer. */
+			if (mp_h) {
+				brelse(mp.mp_bh[mp_h]);
+				mp.mp_bh[mp_h] = NULL;
+			}
+			/* If we can't get any lower in height, we've stripped
+			   off all we can. Next step is to back up and start
+			   stripping the previous level of metadata. */
+			if (mp_h == 0) {
+				strip_h--;
+				memcpy(mp.mp_list, start_list, sizeof(start_list));
+				mp_h = strip_h;
+				state = DEALLOC_FILL_MP;
+				break;
+			}
+			mp.mp_list[mp_h] = 0;
+			mp_h--; /* search one metadata height down */
+			mp.mp_list[mp_h]++;
+			if (walk_done(sdp, &mp, mp_h, end_list, end_aligned))
+				break;
+			/* Here we've found a part of the metapath that is not
+			 * allocated. We need to search at that height for the
+			 * next non-null pointer. */
+			if (find_nonnull_ptr(sdp, &mp, mp_h, end_list, end_aligned)) {
+				state = DEALLOC_FILL_MP;
+				mp_h++;
+			}
+			/* No more non-null pointers at this height. Back up
+			   to the previous height and try again. */
+			break; /* loop around in the same state */
+
+		/* Fill the metapath with buffers to the given height. */
+		case DEALLOC_FILL_MP:
+			/* Fill the buffers out to the current height. */
+			ret = fillup_metapath(ip, &mp, mp_h);
+			if (ret < 0)
+				goto out;
+
+			/* On the first pass, issue read-ahead on metadata. */
+			if (mp.mp_aheight > 1 && strip_h == ip->i_height - 1) {
+				unsigned int height = mp.mp_aheight - 1;
+
+				/* No read-ahead for data blocks. */
+				if (mp.mp_aheight - 1 == strip_h)
+					height--;
+
+				for (; height >= mp.mp_aheight - ret; height--) {
+					metapointer_range(&mp, height,
+							  start_list, start_aligned,
+							  end_list, end_aligned,
+							  &start, &end);
+					gfs2_metapath_ra(ip->i_gl, start, end);
+				}
+			}
+
+			/* If buffers found for the entire strip height */
+			if (mp.mp_aheight - 1 == strip_h) {
+				state = DEALLOC_MP_FULL;
+				break;
+			}
+			if (mp.mp_aheight < ip->i_height) /* We have a partial height */
+				mp_h = mp.mp_aheight - 1;
+
+			/* If we find a non-null block pointer, crawl a bit
+			   higher up in the metapath and try again, otherwise
+			   we need to look lower for a new starting point. */
+			if (find_nonnull_ptr(sdp, &mp, mp_h, end_list, end_aligned))
+				mp_h++;
+			else
+				state = DEALLOC_MP_LOWER;
+			break;
+		}
+	}
+
+	if (btotal) {
+		if (current->journal_info == NULL) {
+			ret = gfs2_trans_begin(sdp, RES_DINODE + RES_STATFS +
+					       RES_QUOTA, 0);
+			if (ret)
+				goto out;
+			down_write(&ip->i_rw_mutex);
+		}
+		gfs2_statfs_change(sdp, 0, +btotal, 0);
+		gfs2_quota_change(ip, -(s64)btotal, ip->i_inode.i_uid,
+				  ip->i_inode.i_gid);
+		ip->i_inode.i_mtime = ip->i_inode.i_ctime = current_time(&ip->i_inode);
+		gfs2_trans_add_meta(ip->i_gl, dibh);
+		gfs2_dinode_out(ip, dibh->b_data);
+		up_write(&ip->i_rw_mutex);
+		gfs2_trans_end(sdp);
+	}
+
+out:
+	if (gfs2_holder_initialized(&rd_gh))
+		gfs2_glock_dq_uninit(&rd_gh);
+	if (current->journal_info) {
+		up_write(&ip->i_rw_mutex);
+		gfs2_trans_end(sdp);
+		cond_resched();
+	}
+	gfs2_quota_unhold(ip);
+out_metapath:
+	release_metapath(&mp);
+	return ret;
+}
+
+static int trunc_end(struct gfs2_inode *ip)
+{
+	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
+	struct buffer_head *dibh;
+	int error;
+
+	error = gfs2_trans_begin(sdp, RES_DINODE, 0);
+	if (error)
+		return error;
+
+	down_write(&ip->i_rw_mutex);
+
+	error = gfs2_meta_inode_buffer(ip, &dibh);
+	if (error)
+		goto out;
+
+	if (!i_size_read(&ip->i_inode)) {
+		ip->i_height = 0;
+		ip->i_goal = ip->i_no_addr;
+		gfs2_buffer_clear_tail(dibh, sizeof(struct gfs2_dinode));
+		gfs2_ordered_del_inode(ip);
+	}
+	ip->i_inode.i_mtime = ip->i_inode.i_ctime = current_time(&ip->i_inode);
+	ip->i_diskflags &= ~GFS2_DIF_TRUNC_IN_PROG;
+
+	gfs2_trans_add_meta(ip->i_gl, dibh);
+	gfs2_dinode_out(ip, dibh->b_data);
+	brelse(dibh);
+
+out:
+	up_write(&ip->i_rw_mutex);
+	gfs2_trans_end(sdp);
+	return error;
+}
+
+/**
+ * do_shrink - make a file smaller
+ * @inode: the inode
+ * @newsize: the size to make the file
+ *
+ * Called with an exclusive lock on @inode. The @size must
+ * be equal to or smaller than the current inode size.
+ *
+ * Returns: errno
+ */
+
+static int do_shrink(struct inode *inode, u64 newsize)
+{
+	struct gfs2_inode *ip = GFS2_I(inode);
+	int error;
+
+	error = trunc_start(inode, newsize);
+	if (error < 0)
+		return error;
+	if (gfs2_is_stuffed(ip))
+		return 0;
+
+	error = punch_hole(ip, newsize, 0);
+	if (error == 0)
+		error = trunc_end(ip);
+
+	return error;
+}
+
+void gfs2_trim_blocks(struct inode *inode)
+{
+	int ret;
+
+	ret = do_shrink(inode, inode->i_size);
+	WARN_ON(ret != 0);
+}
+
+/**
+ * do_grow - Touch and update inode size
+ * @inode: The inode
+ * @size: The new size
+ *
+ * This function updates the timestamps on the inode and
+ * may also increase the size of the inode. This function
+ * must not be called with @size any smaller than the current
+ * inode size.
+ *
+ * Although it is not strictly required to unstuff files here,
+ * earlier versions of GFS2 have a bug in the stuffed file reading
+ * code which will result in a buffer overrun if the size is larger
+ * than the max stuffed file size. In order to prevent this from
+ * occurring, such files are unstuffed, but in other cases we can
+ * just update the inode size directly.
+ *
+ * Returns: 0 on success, or -ve on error
+ */
+
+static int do_grow(struct inode *inode, u64 size)
+{
+	struct gfs2_inode *ip = GFS2_I(inode);
+	struct gfs2_sbd *sdp = GFS2_SB(inode);
+	struct gfs2_alloc_parms ap = { .target = 1, };
+	struct buffer_head *dibh;
+	int error;
+	int unstuff = 0;
+
+	if (gfs2_is_stuffed(ip) && size > gfs2_max_stuffed_size(ip)) {
+		error = gfs2_quota_lock_check(ip, &ap);
+		if (error)
+			return error;
+
+		error = gfs2_inplace_reserve(ip, &ap);
+		if (error)
+			goto do_grow_qunlock;
+		unstuff = 1;
+	}
+
+	error = gfs2_trans_begin(sdp, RES_DINODE + RES_STATFS + RES_RG_BIT +
+				 (unstuff &&
+				  gfs2_is_jdata(ip) ? RES_JDATA : 0) +
+				 (sdp->sd_args.ar_quota == GFS2_QUOTA_OFF ?
+				  0 : RES_QUOTA), 0);
+	if (error)
+		goto do_grow_release;
+
+	if (unstuff) {
+		error = gfs2_unstuff_dinode(ip, NULL);
+		if (error)
+			goto do_end_trans;
+	}
+
+	error = gfs2_meta_inode_buffer(ip, &dibh);
+	if (error)
+		goto do_end_trans;
+
+	i_size_write(inode, size);
+	ip->i_inode.i_mtime = ip->i_inode.i_ctime = current_time(&ip->i_inode);
+	gfs2_trans_add_meta(ip->i_gl, dibh);
+	gfs2_dinode_out(ip, dibh->b_data);
+	brelse(dibh);
+
+do_end_trans:
+	gfs2_trans_end(sdp);
+do_grow_release:
+	if (unstuff) {
+		gfs2_inplace_release(ip);
+do_grow_qunlock:
+		gfs2_quota_unlock(ip);
+	}
+	return error;
+}
+
+/**
+ * gfs2_setattr_size - make a file a given size
+ * @inode: the inode
+ * @newsize: the size to make the file
+ *
+ * The file size can grow, shrink, or stay the same size. This
+ * is called holding i_rwsem and an exclusive glock on the inode
+ * in question.
+ *
+ * Returns: errno
+ */
+
+int gfs2_setattr_size(struct inode *inode, u64 newsize)
+{
+	struct gfs2_inode *ip = GFS2_I(inode);
+	int ret;
+
+	BUG_ON(!S_ISREG(inode->i_mode));
+
+	ret = inode_newsize_ok(inode, newsize);
+	if (ret)
+		return ret;
+
+	inode_dio_wait(inode);
+
+	ret = gfs2_rsqa_alloc(ip);
+	if (ret)
+		goto out;
+
+	if (newsize >= inode->i_size) {
+		ret = do_grow(inode, newsize);
+		goto out;
+	}
+
+	ret = do_shrink(inode, newsize);
+out:
+	gfs2_rsqa_delete(ip, NULL);
+	return ret;
+}
+
+int gfs2_truncatei_resume(struct gfs2_inode *ip)
+{
+	int error;
+	error = punch_hole(ip, i_size_read(&ip->i_inode), 0);
+	if (!error)
+		error = trunc_end(ip);
+	return error;
+}
+
+int gfs2_file_dealloc(struct gfs2_inode *ip)
+{
+	return punch_hole(ip, 0, 0);
+}
+
+/**
+ * gfs2_free_journal_extents - Free cached journal bmap info
+ * @jd: The journal
+ *
+ */
+
+void gfs2_free_journal_extents(struct gfs2_jdesc *jd)
+{
+	struct gfs2_journal_extent *jext;
+
+	while(!list_empty(&jd->extent_list)) {
+		jext = list_entry(jd->extent_list.next, struct gfs2_journal_extent, list);
+		list_del(&jext->list);
+		kfree(jext);
+	}
+}
+
+/**
+ * gfs2_add_jextent - Add or merge a new extent to extent cache
+ * @jd: The journal descriptor
+ * @lblock: The logical block at start of new extent
+ * @dblock: The physical block at start of new extent
+ * @blocks: Size of extent in fs blocks
+ *
+ * Returns: 0 on success or -ENOMEM
+ */
+
+static int gfs2_add_jextent(struct gfs2_jdesc *jd, u64 lblock, u64 dblock, u64 blocks)
+{
+	struct gfs2_journal_extent *jext;
+
+	if (!list_empty(&jd->extent_list)) {
+		jext = list_entry(jd->extent_list.prev, struct gfs2_journal_extent, list);
+		if ((jext->dblock + jext->blocks) == dblock) {
+			jext->blocks += blocks;
+			return 0;
+		}
+	}
+
+	jext = kzalloc(sizeof(struct gfs2_journal_extent), GFP_NOFS);
+	if (jext == NULL)
+		return -ENOMEM;
+	jext->dblock = dblock;
+	jext->lblock = lblock;
+	jext->blocks = blocks;
+	list_add_tail(&jext->list, &jd->extent_list);
+	jd->nr_extents++;
+	return 0;
+}
+
+/**
+ * gfs2_map_journal_extents - Cache journal bmap info
+ * @sdp: The super block
+ * @jd: The journal to map
+ *
+ * Create a reusable "extent" mapping from all logical
+ * blocks to all physical blocks for the given journal.  This will save
+ * us time when writing journal blocks.  Most journals will have only one
+ * extent that maps all their logical blocks.  That's because gfs2.mkfs
+ * arranges the journal blocks sequentially to maximize performance.
+ * So the extent would map the first block for the entire file length.
+ * However, gfs2_jadd can happen while file activity is happening, so
+ * those journals may not be sequential.  Less likely is the case where
+ * the users created their own journals by mounting the metafs and
+ * laying it out.  But it's still possible.  These journals might have
+ * several extents.
+ *
+ * Returns: 0 on success, or error on failure
+ */
+
+int gfs2_map_journal_extents(struct gfs2_sbd *sdp, struct gfs2_jdesc *jd)
+{
+	u64 lblock = 0;
+	u64 lblock_stop;
+	struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
+	struct buffer_head bh;
+	unsigned int shift = sdp->sd_sb.sb_bsize_shift;
+	u64 size;
+	int rc;
+
+	lblock_stop = i_size_read(jd->jd_inode) >> shift;
+	size = (lblock_stop - lblock) << shift;
+	jd->nr_extents = 0;
+	WARN_ON(!list_empty(&jd->extent_list));
+
+	do {
+		bh.b_state = 0;
+		bh.b_blocknr = 0;
+		bh.b_size = size;
+		rc = gfs2_block_map(jd->jd_inode, lblock, &bh, 0);
+		if (rc || !buffer_mapped(&bh))
+			goto fail;
+		rc = gfs2_add_jextent(jd, lblock, bh.b_blocknr, bh.b_size >> shift);
+		if (rc)
+			goto fail;
+		size -= bh.b_size;
+		lblock += (bh.b_size >> ip->i_inode.i_blkbits);
+	} while(size > 0);
+
+	fs_info(sdp, "journal %d mapped with %u extents\n", jd->jd_jid,
+		jd->nr_extents);
+	return 0;
+
+fail:
+	fs_warn(sdp, "error %d mapping journal %u at offset %llu (extent %u)\n",
+		rc, jd->jd_jid,
+		(unsigned long long)(i_size_read(jd->jd_inode) - size),
+		jd->nr_extents);
+	fs_warn(sdp, "bmap=%d lblock=%llu block=%llu, state=0x%08lx, size=%llu\n",
+		rc, (unsigned long long)lblock, (unsigned long long)bh.b_blocknr,
+		bh.b_state, (unsigned long long)bh.b_size);
+	gfs2_free_journal_extents(jd);
+	return rc;
+}
+
+/**
+ * gfs2_write_alloc_required - figure out if a write will require an allocation
+ * @ip: the file being written to
+ * @offset: the offset to write to
+ * @len: the number of bytes being written
+ *
+ * Returns: 1 if an alloc is required, 0 otherwise
+ */
+
+int gfs2_write_alloc_required(struct gfs2_inode *ip, u64 offset,
+			      unsigned int len)
+{
+	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
+	struct buffer_head bh;
+	unsigned int shift;
+	u64 lblock, lblock_stop, size;
+	u64 end_of_file;
+
+	if (!len)
+		return 0;
+
+	if (gfs2_is_stuffed(ip)) {
+		if (offset + len > gfs2_max_stuffed_size(ip))
+			return 1;
+		return 0;
+	}
+
+	shift = sdp->sd_sb.sb_bsize_shift;
+	BUG_ON(gfs2_is_dir(ip));
+	end_of_file = (i_size_read(&ip->i_inode) + sdp->sd_sb.sb_bsize - 1) >> shift;
+	lblock = offset >> shift;
+	lblock_stop = (offset + len + sdp->sd_sb.sb_bsize - 1) >> shift;
+	if (lblock_stop > end_of_file && ip != GFS2_I(sdp->sd_rindex))
+		return 1;
+
+	size = (lblock_stop - lblock) << shift;
+	do {
+		bh.b_state = 0;
+		bh.b_size = size;
+		gfs2_block_map(&ip->i_inode, lblock, &bh, 0);
+		if (!buffer_mapped(&bh))
+			return 1;
+		size -= bh.b_size;
+		lblock += (bh.b_size >> ip->i_inode.i_blkbits);
+	} while(size > 0);
+
+	return 0;
+}
+
+static int stuffed_zero_range(struct inode *inode, loff_t offset, loff_t length)
+{
+	struct gfs2_inode *ip = GFS2_I(inode);
+	struct buffer_head *dibh;
+	int error;
+
+	if (offset >= inode->i_size)
+		return 0;
+	if (offset + length > inode->i_size)
+		length = inode->i_size - offset;
+
+	error = gfs2_meta_inode_buffer(ip, &dibh);
+	if (error)
+		return error;
+	gfs2_trans_add_meta(ip->i_gl, dibh);
+	memset(dibh->b_data + sizeof(struct gfs2_dinode) + offset, 0,
+	       length);
+	brelse(dibh);
+	return 0;
+}
+
+static int gfs2_journaled_truncate_range(struct inode *inode, loff_t offset,
+					 loff_t length)
+{
+	struct gfs2_sbd *sdp = GFS2_SB(inode);
+	loff_t max_chunk = GFS2_JTRUNC_REVOKES * sdp->sd_vfs->s_blocksize;
+	int error;
+
+	while (length) {
+		struct gfs2_trans *tr;
+		loff_t chunk;
+		unsigned int offs;
+
+		chunk = length;
+		if (chunk > max_chunk)
+			chunk = max_chunk;
+
+		offs = offset & ~PAGE_MASK;
+		if (offs && chunk > PAGE_SIZE)
+			chunk = offs + ((chunk - offs) & PAGE_MASK);
+
+		truncate_pagecache_range(inode, offset, chunk);
+		offset += chunk;
+		length -= chunk;
+
+		tr = current->journal_info;
+		if (!test_bit(TR_TOUCHED, &tr->tr_flags))
+			continue;
+
+		gfs2_trans_end(sdp);
+		error = gfs2_trans_begin(sdp, RES_DINODE, GFS2_JTRUNC_REVOKES);
+		if (error)
+			return error;
+	}
+	return 0;
+}
+
+int __gfs2_punch_hole(struct file *file, loff_t offset, loff_t length)
+{
+	struct inode *inode = file_inode(file);
+	struct gfs2_inode *ip = GFS2_I(inode);
+	struct gfs2_sbd *sdp = GFS2_SB(inode);
+	int error;
+
+	if (gfs2_is_jdata(ip))
+		error = gfs2_trans_begin(sdp, RES_DINODE + 2 * RES_JDATA,
+					 GFS2_JTRUNC_REVOKES);
+	else
+		error = gfs2_trans_begin(sdp, RES_DINODE, 0);
+	if (error)
+		return error;
+
+	if (gfs2_is_stuffed(ip)) {
+		error = stuffed_zero_range(inode, offset, length);
+		if (error)
+			goto out;
+	} else {
+		unsigned int start_off, end_len, blocksize;
+
+		blocksize = i_blocksize(inode);
+		start_off = offset & (blocksize - 1);
+		end_len = (offset + length) & (blocksize - 1);
+		if (start_off) {
+			unsigned int len = length;
+			if (length > blocksize - start_off)
+				len = blocksize - start_off;
+			error = gfs2_block_zero_range(inode, offset, len);
+			if (error)
+				goto out;
+			if (start_off + length < blocksize)
+				end_len = 0;
+		}
+		if (end_len) {
+			error = gfs2_block_zero_range(inode,
+				offset + length - end_len, end_len);
+			if (error)
+				goto out;
+		}
+	}
+
+	if (gfs2_is_jdata(ip)) {
+		BUG_ON(!current->journal_info);
+		gfs2_journaled_truncate_range(inode, offset, length);
+	} else
+		truncate_pagecache_range(inode, offset, offset + length - 1);
+
+	file_update_time(file);
+	mark_inode_dirty(inode);
+
+	if (current->journal_info)
+		gfs2_trans_end(sdp);
+
+	if (!gfs2_is_stuffed(ip))
+		error = punch_hole(ip, offset, length);
+
+out:
+	if (current->journal_info)
+		gfs2_trans_end(sdp);
+	return error;
+}