Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable

1 files changed, 1299 insertions, 0 deletions

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
new file mode 100644
index 0000000..1e8c024
--- /dev/null
+++ b/fs/btrfs/file.c
@@ -0,0 +1,1299 @@
+/*
+ * Copyright (C) 2007 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#include <linux/fs.h>
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <linux/time.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/smp_lock.h>
+#include <linux/backing-dev.h>
+#include <linux/mpage.h>
+#include <linux/swap.h>
+#include <linux/writeback.h>
+#include <linux/statfs.h>
+#include <linux/compat.h>
+#include <linux/version.h>
+#include "ctree.h"
+#include "disk-io.h"
+#include "transaction.h"
+#include "btrfs_inode.h"
+#include "ioctl.h"
+#include "print-tree.h"
+#include "tree-log.h"
+#include "locking.h"
+#include "compat.h"
+
+
+/* simple helper to fault in pages and copy.  This should go away
+ * and be replaced with calls into generic code.
+ */
+static int noinline btrfs_copy_from_user(loff_t pos, int num_pages,
+					 int write_bytes,
+					 struct page **prepared_pages,
+					 const char __user * buf)
+{
+	long page_fault = 0;
+	int i;
+	int offset = pos & (PAGE_CACHE_SIZE - 1);
+
+	for (i = 0; i < num_pages && write_bytes > 0; i++, offset = 0) {
+		size_t count = min_t(size_t,
+				     PAGE_CACHE_SIZE - offset, write_bytes);
+		struct page *page = prepared_pages[i];
+		fault_in_pages_readable(buf, count);
+
+		/* Copy data from userspace to the current page */
+		kmap(page);
+		page_fault = __copy_from_user(page_address(page) + offset,
+					      buf, count);
+		/* Flush processor's dcache for this page */
+		flush_dcache_page(page);
+		kunmap(page);
+		buf += count;
+		write_bytes -= count;
+
+		if (page_fault)
+			break;
+	}
+	return page_fault ? -EFAULT : 0;
+}
+
+/*
+ * unlocks pages after btrfs_file_write is done with them
+ */
+static void noinline btrfs_drop_pages(struct page **pages, size_t num_pages)
+{
+	size_t i;
+	for (i = 0; i < num_pages; i++) {
+		if (!pages[i])
+			break;
+		/* page checked is some magic around finding pages that
+		 * have been modified without going through btrfs_set_page_dirty
+		 * clear it here
+		 */
+		ClearPageChecked(pages[i]);
+		unlock_page(pages[i]);
+		mark_page_accessed(pages[i]);
+		page_cache_release(pages[i]);
+	}
+}
+
+/*
+ * after copy_from_user, pages need to be dirtied and we need to make
+ * sure holes are created between the current EOF and the start of
+ * any next extents (if required).
+ *
+ * this also makes the decision about creating an inline extent vs
+ * doing real data extents, marking pages dirty and delalloc as required.
+ */
+static int noinline dirty_and_release_pages(struct btrfs_trans_handle *trans,
+				   struct btrfs_root *root,
+				   struct file *file,
+				   struct page **pages,
+				   size_t num_pages,
+				   loff_t pos,
+				   size_t write_bytes)
+{
+	int err = 0;
+	int i;
+	struct inode *inode = fdentry(file)->d_inode;
+	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
+	u64 hint_byte;
+	u64 num_bytes;
+	u64 start_pos;
+	u64 end_of_last_block;
+	u64 end_pos = pos + write_bytes;
+	loff_t isize = i_size_read(inode);
+
+	start_pos = pos & ~((u64)root->sectorsize - 1);
+	num_bytes = (write_bytes + pos - start_pos +
+		    root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
+
+	end_of_last_block = start_pos + num_bytes - 1;
+
+	lock_extent(io_tree, start_pos, end_of_last_block, GFP_NOFS);
+	trans = btrfs_join_transaction(root, 1);
+	if (!trans) {
+		err = -ENOMEM;
+		goto out_unlock;
+	}
+	btrfs_set_trans_block_group(trans, inode);
+	hint_byte = 0;
+
+	if ((end_of_last_block & 4095) == 0) {
+		printk("strange end of last %Lu %zu %Lu\n", start_pos, write_bytes, end_of_last_block);
+	}
+	set_extent_uptodate(io_tree, start_pos, end_of_last_block, GFP_NOFS);
+
+	/* check for reserved extents on each page, we don't want
+	 * to reset the delalloc bit on things that already have
+	 * extents reserved.
+	 */
+	btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block);
+	for (i = 0; i < num_pages; i++) {
+		struct page *p = pages[i];
+		SetPageUptodate(p);
+		ClearPageChecked(p);
+		set_page_dirty(p);
+	}
+	if (end_pos > isize) {
+		i_size_write(inode, end_pos);
+		btrfs_update_inode(trans, root, inode);
+	}
+	err = btrfs_end_transaction(trans, root);
+out_unlock:
+	unlock_extent(io_tree, start_pos, end_of_last_block, GFP_NOFS);
+	return err;
+}
+
+/*
+ * this drops all the extents in the cache that intersect the range
+ * [start, end].  Existing extents are split as required.
+ */
+int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
+			    int skip_pinned)
+{
+	struct extent_map *em;
+	struct extent_map *split = NULL;
+	struct extent_map *split2 = NULL;
+	struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
+	u64 len = end - start + 1;
+	int ret;
+	int testend = 1;
+	unsigned long flags;
+	int compressed = 0;
+
+	WARN_ON(end < start);
+	if (end == (u64)-1) {
+		len = (u64)-1;
+		testend = 0;
+	}
+	while(1) {
+		if (!split)
+			split = alloc_extent_map(GFP_NOFS);
+		if (!split2)
+			split2 = alloc_extent_map(GFP_NOFS);
+
+		spin_lock(&em_tree->lock);
+		em = lookup_extent_mapping(em_tree, start, len);
+		if (!em) {
+			spin_unlock(&em_tree->lock);
+			break;
+		}
+		flags = em->flags;
+		if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
+			spin_unlock(&em_tree->lock);
+			if (em->start <= start &&
+			    (!testend || em->start + em->len >= start + len)) {
+				free_extent_map(em);
+				break;
+			}
+			if (start < em->start) {
+				len = em->start - start;
+			} else {
+				len = start + len - (em->start + em->len);
+				start = em->start + em->len;
+			}
+			free_extent_map(em);
+			continue;
+		}
+		compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
+		clear_bit(EXTENT_FLAG_PINNED, &em->flags);
+		remove_extent_mapping(em_tree, em);
+
+		if (em->block_start < EXTENT_MAP_LAST_BYTE &&
+		    em->start < start) {
+			split->start = em->start;
+			split->len = start - em->start;
+			split->orig_start = em->orig_start;
+			split->block_start = em->block_start;
+
+			if (compressed)
+				split->block_len = em->block_len;
+			else
+				split->block_len = split->len;
+
+			split->bdev = em->bdev;
+			split->flags = flags;
+			ret = add_extent_mapping(em_tree, split);
+			BUG_ON(ret);
+			free_extent_map(split);
+			split = split2;
+			split2 = NULL;
+		}
+		if (em->block_start < EXTENT_MAP_LAST_BYTE &&
+		    testend && em->start + em->len > start + len) {
+			u64 diff = start + len - em->start;
+
+			split->start = start + len;
+			split->len = em->start + em->len - (start + len);
+			split->bdev = em->bdev;
+			split->flags = flags;
+
+			if (compressed) {
+				split->block_len = em->block_len;
+				split->block_start = em->block_start;
+				split->orig_start = em->orig_start;
+			} else {
+				split->block_len = split->len;
+				split->block_start = em->block_start + diff;
+				split->orig_start = split->start;
+			}
+
+			ret = add_extent_mapping(em_tree, split);
+			BUG_ON(ret);
+			free_extent_map(split);
+			split = NULL;
+		}
+		spin_unlock(&em_tree->lock);
+
+		/* once for us */
+		free_extent_map(em);
+		/* once for the tree*/
+		free_extent_map(em);
+	}
+	if (split)
+		free_extent_map(split);
+	if (split2)
+		free_extent_map(split2);
+	return 0;
+}
+
+int btrfs_check_file(struct btrfs_root *root, struct inode *inode)
+{
+	return 0;
+#if 0
+	struct btrfs_path *path;
+	struct btrfs_key found_key;
+	struct extent_buffer *leaf;
+	struct btrfs_file_extent_item *extent;
+	u64 last_offset = 0;
+	int nritems;
+	int slot;
+	int found_type;
+	int ret;
+	int err = 0;
+	u64 extent_end = 0;
+
+	path = btrfs_alloc_path();
+	ret = btrfs_lookup_file_extent(NULL, root, path, inode->i_ino,
+				       last_offset, 0);
+	while(1) {
+		nritems = btrfs_header_nritems(path->nodes[0]);
+		if (path->slots[0] >= nritems) {
+			ret = btrfs_next_leaf(root, path);
+			if (ret)
+				goto out;
+			nritems = btrfs_header_nritems(path->nodes[0]);
+		}
+		slot = path->slots[0];
+		leaf = path->nodes[0];
+		btrfs_item_key_to_cpu(leaf, &found_key, slot);
+		if (found_key.objectid != inode->i_ino)
+			break;
+		if (found_key.type != BTRFS_EXTENT_DATA_KEY)
+			goto out;
+
+		if (found_key.offset < last_offset) {
+			WARN_ON(1);
+			btrfs_print_leaf(root, leaf);
+			printk("inode %lu found offset %Lu expected %Lu\n",
+			       inode->i_ino, found_key.offset, last_offset);
+			err = 1;
+			goto out;
+		}
+		extent = btrfs_item_ptr(leaf, slot,
+					struct btrfs_file_extent_item);
+		found_type = btrfs_file_extent_type(leaf, extent);
+		if (found_type == BTRFS_FILE_EXTENT_REG) {
+			extent_end = found_key.offset +
+			     btrfs_file_extent_num_bytes(leaf, extent);
+		} else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
+			struct btrfs_item *item;
+			item = btrfs_item_nr(leaf, slot);
+			extent_end = found_key.offset +
+			     btrfs_file_extent_inline_len(leaf, extent);
+			extent_end = (extent_end + root->sectorsize - 1) &
+				~((u64)root->sectorsize -1 );
+		}
+		last_offset = extent_end;
+		path->slots[0]++;
+	}
+	if (0 && last_offset < inode->i_size) {
+		WARN_ON(1);
+		btrfs_print_leaf(root, leaf);
+		printk("inode %lu found offset %Lu size %Lu\n", inode->i_ino,
+		       last_offset, inode->i_size);
+		err = 1;
+
+	}
+out:
+	btrfs_free_path(path);
+	return err;
+#endif
+}
+
+/*
+ * this is very complex, but the basic idea is to drop all extents
+ * in the range start - end.  hint_block is filled in with a block number
+ * that would be a good hint to the block allocator for this file.
+ *
+ * If an extent intersects the range but is not entirely inside the range
+ * it is either truncated or split.  Anything entirely inside the range
+ * is deleted from the tree.
+ *
+ * inline_limit is used to tell this code which offsets in the file to keep
+ * if they contain inline extents.
+ */
+int noinline btrfs_drop_extents(struct btrfs_trans_handle *trans,
+		       struct btrfs_root *root, struct inode *inode,
+		       u64 start, u64 end, u64 inline_limit, u64 *hint_byte)
+{
+	u64 extent_end = 0;
+	u64 locked_end = end;
+	u64 search_start = start;
+	u64 leaf_start;
+	u64 ram_bytes = 0;
+	u64 orig_parent = 0;
+	u64 disk_bytenr = 0;
+	u8 compression;
+	u8 encryption;
+	u16 other_encoding = 0;
+	u64 root_gen;
+	u64 root_owner;
+	struct extent_buffer *leaf;
+	struct btrfs_file_extent_item *extent;
+	struct btrfs_path *path;
+	struct btrfs_key key;
+	struct btrfs_file_extent_item old;
+	int keep;
+	int slot;
+	int bookend;
+	int found_type = 0;
+	int found_extent;
+	int found_inline;
+	int recow;
+	int ret;
+
+	inline_limit = 0;
+	btrfs_drop_extent_cache(inode, start, end - 1, 0);
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+	while(1) {
+		recow = 0;
+		btrfs_release_path(root, path);
+		ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,
+					       search_start, -1);
+		if (ret < 0)
+			goto out;
+		if (ret > 0) {
+			if (path->slots[0] == 0) {
+				ret = 0;
+				goto out;
+			}
+			path->slots[0]--;
+		}
+next_slot:
+		keep = 0;
+		bookend = 0;
+		found_extent = 0;
+		found_inline = 0;
+		leaf_start = 0;
+		root_gen = 0;
+		root_owner = 0;
+		compression = 0;
+		encryption = 0;
+		extent = NULL;
+		leaf = path->nodes[0];
+		slot = path->slots[0];
+		ret = 0;
+		btrfs_item_key_to_cpu(leaf, &key, slot);
+		if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY &&
+		    key.offset >= end) {
+			goto out;
+		}
+		if (btrfs_key_type(&key) > BTRFS_EXTENT_DATA_KEY ||
+		    key.objectid != inode->i_ino) {
+			goto out;
+		}
+		if (recow) {
+			search_start = max(key.offset, start);
+			continue;
+		}
+		if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY) {
+			extent = btrfs_item_ptr(leaf, slot,
+						struct btrfs_file_extent_item);
+			found_type = btrfs_file_extent_type(leaf, extent);
+			compression = btrfs_file_extent_compression(leaf,
+								    extent);
+			encryption = btrfs_file_extent_encryption(leaf,
+								  extent);
+			other_encoding = btrfs_file_extent_other_encoding(leaf,
+								  extent);
+			if (found_type == BTRFS_FILE_EXTENT_REG ||
+			    found_type == BTRFS_FILE_EXTENT_PREALLOC) {
+				extent_end =
+				     btrfs_file_extent_disk_bytenr(leaf,
+								   extent);
+				if (extent_end)
+					*hint_byte = extent_end;
+
+				extent_end = key.offset +
+				     btrfs_file_extent_num_bytes(leaf, extent);
+				ram_bytes = btrfs_file_extent_ram_bytes(leaf,
+								extent);
+				found_extent = 1;
+			} else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
+				found_inline = 1;
+				extent_end = key.offset +
+				     btrfs_file_extent_inline_len(leaf, extent);
+			}
+		} else {
+			extent_end = search_start;
+		}
+
+		/* we found nothing we can drop */
+		if ((!found_extent && !found_inline) ||
+		    search_start >= extent_end) {
+			int nextret;
+			u32 nritems;
+			nritems = btrfs_header_nritems(leaf);
+			if (slot >= nritems - 1) {
+				nextret = btrfs_next_leaf(root, path);
+				if (nextret)
+					goto out;
+				recow = 1;
+			} else {
+				path->slots[0]++;
+			}
+			goto next_slot;
+		}
+
+		if (end <= extent_end && start >= key.offset && found_inline)
+			*hint_byte = EXTENT_MAP_INLINE;
+
+		if (found_extent) {
+			read_extent_buffer(leaf, &old, (unsigned long)extent,
+					   sizeof(old));
+			root_gen = btrfs_header_generation(leaf);
+			root_owner = btrfs_header_owner(leaf);
+			leaf_start = leaf->start;
+		}
+
+		if (end < extent_end && end >= key.offset) {
+			bookend = 1;
+			if (found_inline && start <= key.offset)
+				keep = 1;
+		}
+
+		if (bookend && found_extent) {
+			if (locked_end < extent_end) {
+				ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
+						locked_end, extent_end - 1,
+						GFP_NOFS);
+				if (!ret) {
+					btrfs_release_path(root, path);
+					lock_extent(&BTRFS_I(inode)->io_tree,
+						locked_end, extent_end - 1,
+						GFP_NOFS);
+					locked_end = extent_end;
+					continue;
+				}
+				locked_end = extent_end;
+			}
+			orig_parent = path->nodes[0]->start;
+			disk_bytenr = le64_to_cpu(old.disk_bytenr);
+			if (disk_bytenr != 0) {
+				ret = btrfs_inc_extent_ref(trans, root,
+					   disk_bytenr,
+					   le64_to_cpu(old.disk_num_bytes),
+					   orig_parent, root->root_key.objectid,
+					   trans->transid, inode->i_ino);
+				BUG_ON(ret);
+			}
+		}
+
+		if (found_inline) {
+			u64 mask = root->sectorsize - 1;
+			search_start = (extent_end + mask) & ~mask;
+		} else
+			search_start = extent_end;
+
+		/* truncate existing extent */
+		if (start > key.offset) {
+			u64 new_num;
+			u64 old_num;
+			keep = 1;
+			WARN_ON(start & (root->sectorsize - 1));
+			if (found_extent) {
+				new_num = start - key.offset;
+				old_num = btrfs_file_extent_num_bytes(leaf,
+								      extent);
+				*hint_byte =
+					btrfs_file_extent_disk_bytenr(leaf,
+								      extent);
+				if (btrfs_file_extent_disk_bytenr(leaf,
+								  extent)) {
+					inode_sub_bytes(inode, old_num -
+							new_num);
+				}
+				if (!compression && !encryption) {
+					btrfs_set_file_extent_ram_bytes(leaf,
+							extent, new_num);
+				}
+				btrfs_set_file_extent_num_bytes(leaf,
+							extent, new_num);
+				btrfs_mark_buffer_dirty(leaf);
+			} else if (key.offset < inline_limit &&
+				   (end > extent_end) &&
+				   (inline_limit < extent_end)) {
+				u32 new_size;
+				new_size = btrfs_file_extent_calc_inline_size(
+						   inline_limit - key.offset);
+				inode_sub_bytes(inode, extent_end -
+						inline_limit);
+				btrfs_set_file_extent_ram_bytes(leaf, extent,
+							new_size);
+				if (!compression && !encryption) {
+					btrfs_truncate_item(trans, root, path,
+							    new_size, 1);
+				}
+			}
+		}
+		/* delete the entire extent */
+		if (!keep) {
+			if (found_inline)
+				inode_sub_bytes(inode, extent_end -
+						key.offset);
+			ret = btrfs_del_item(trans, root, path);
+			/* TODO update progress marker and return */
+			BUG_ON(ret);
+			extent = NULL;
+			btrfs_release_path(root, path);
+			/* the extent will be freed later */
+		}
+		if (bookend && found_inline && start <= key.offset) {
+			u32 new_size;
+			new_size = btrfs_file_extent_calc_inline_size(
+						   extent_end - end);
+			inode_sub_bytes(inode, end - key.offset);
+			btrfs_set_file_extent_ram_bytes(leaf, extent,
+							new_size);
+			if (!compression && !encryption)
+				ret = btrfs_truncate_item(trans, root, path,
+							  new_size, 0);
+			BUG_ON(ret);
+		}
+		/* create bookend, splitting the extent in two */
+		if (bookend && found_extent) {
+			struct btrfs_key ins;
+			ins.objectid = inode->i_ino;
+			ins.offset = end;
+			btrfs_set_key_type(&ins, BTRFS_EXTENT_DATA_KEY);
+
+			btrfs_release_path(root, path);
+			ret = btrfs_insert_empty_item(trans, root, path, &ins,
+						      sizeof(*extent));
+			BUG_ON(ret);
+
+			leaf = path->nodes[0];
+			extent = btrfs_item_ptr(leaf, path->slots[0],
+						struct btrfs_file_extent_item);
+			write_extent_buffer(leaf, &old,
+					    (unsigned long)extent, sizeof(old));
+
+			btrfs_set_file_extent_compression(leaf, extent,
+							  compression);
+			btrfs_set_file_extent_encryption(leaf, extent,
+							 encryption);
+			btrfs_set_file_extent_other_encoding(leaf, extent,
+							     other_encoding);
+			btrfs_set_file_extent_offset(leaf, extent,
+				    le64_to_cpu(old.offset) + end - key.offset);
+			WARN_ON(le64_to_cpu(old.num_bytes) <
+				(extent_end - end));
+			btrfs_set_file_extent_num_bytes(leaf, extent,
+							extent_end - end);
+
+			/*
+			 * set the ram bytes to the size of the full extent
+			 * before splitting.  This is a worst case flag,
+			 * but its the best we can do because we don't know
+			 * how splitting affects compression
+			 */
+			btrfs_set_file_extent_ram_bytes(leaf, extent,
+							ram_bytes);
+			btrfs_set_file_extent_type(leaf, extent, found_type);
+
+			btrfs_mark_buffer_dirty(path->nodes[0]);
+
+			if (disk_bytenr != 0) {
+				ret = btrfs_update_extent_ref(trans, root,
+						disk_bytenr, orig_parent,
+					        leaf->start,
+						root->root_key.objectid,
+						trans->transid, ins.objectid);
+
+				BUG_ON(ret);
+			}
+			btrfs_release_path(root, path);
+			if (disk_bytenr != 0) {
+				inode_add_bytes(inode, extent_end - end);
+			}
+		}
+
+		if (found_extent && !keep) {
+			u64 disk_bytenr = le64_to_cpu(old.disk_bytenr);
+
+			if (disk_bytenr != 0) {
+				inode_sub_bytes(inode,
+						le64_to_cpu(old.num_bytes));
+				ret = btrfs_free_extent(trans, root,
+						disk_bytenr,
+						le64_to_cpu(old.disk_num_bytes),
+						leaf_start, root_owner,
+						root_gen, key.objectid, 0);
+				BUG_ON(ret);
+				*hint_byte = disk_bytenr;
+			}
+		}
+
+		if (search_start >= end) {
+			ret = 0;
+			goto out;
+		}
+	}
+out:
+	btrfs_free_path(path);
+	if (locked_end > end) {
+		unlock_extent(&BTRFS_I(inode)->io_tree, end, locked_end - 1,
+			      GFP_NOFS);
+	}
+	btrfs_check_file(root, inode);
+	return ret;
+}
+
+static int extent_mergeable(struct extent_buffer *leaf, int slot,
+			    u64 objectid, u64 bytenr, u64 *start, u64 *end)
+{
+	struct btrfs_file_extent_item *fi;
+	struct btrfs_key key;
+	u64 extent_end;
+
+	if (slot < 0 || slot >= btrfs_header_nritems(leaf))
+		return 0;
+
+	btrfs_item_key_to_cpu(leaf, &key, slot);
+	if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
+		return 0;
+
+	fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
+	if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
+	    btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
+	    btrfs_file_extent_compression(leaf, fi) ||
+	    btrfs_file_extent_encryption(leaf, fi) ||
+	    btrfs_file_extent_other_encoding(leaf, fi))
+		return 0;
+
+	extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
+	if ((*start && *start != key.offset) || (*end && *end != extent_end))
+		return 0;
+
+	*start = key.offset;
+	*end = extent_end;
+	return 1;
+}
+
+/*
+ * Mark extent in the range start - end as written.
+ *
+ * This changes extent type from 'pre-allocated' to 'regular'. If only
+ * part of extent is marked as written, the extent will be split into
+ * two or three.
+ */
+int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
+			      struct btrfs_root *root,
+			      struct inode *inode, u64 start, u64 end)
+{
+	struct extent_buffer *leaf;
+	struct btrfs_path *path;
+	struct btrfs_file_extent_item *fi;
+	struct btrfs_key key;
+	u64 bytenr;
+	u64 num_bytes;
+	u64 extent_end;
+	u64 extent_offset;
+	u64 other_start;
+	u64 other_end;
+	u64 split = start;
+	u64 locked_end = end;
+	u64 orig_parent;
+	int extent_type;
+	int split_end = 1;
+	int ret;
+
+	btrfs_drop_extent_cache(inode, start, end - 1, 0);
+
+	path = btrfs_alloc_path();
+	BUG_ON(!path);
+again:
+	key.objectid = inode->i_ino;
+	key.type = BTRFS_EXTENT_DATA_KEY;
+	if (split == start)
+		key.offset = split;
+	else
+		key.offset = split - 1;
+
+	ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
+	if (ret > 0 && path->slots[0] > 0)
+		path->slots[0]--;
+
+	leaf = path->nodes[0];
+	btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+	BUG_ON(key.objectid != inode->i_ino ||
+	       key.type != BTRFS_EXTENT_DATA_KEY);
+	fi = btrfs_item_ptr(leaf, path->slots[0],
+			    struct btrfs_file_extent_item);
+	extent_type = btrfs_file_extent_type(leaf, fi);
+	BUG_ON(extent_type != BTRFS_FILE_EXTENT_PREALLOC);
+	extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
+	BUG_ON(key.offset > start || extent_end < end);
+
+	bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
+	num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
+	extent_offset = btrfs_file_extent_offset(leaf, fi);
+
+	if (key.offset == start)
+		split = end;
+
+	if (key.offset == start && extent_end == end) {
+		int del_nr = 0;
+		int del_slot = 0;
+		u64 leaf_owner = btrfs_header_owner(leaf);
+		u64 leaf_gen = btrfs_header_generation(leaf);
+		other_start = end;
+		other_end = 0;
+		if (extent_mergeable(leaf, path->slots[0] + 1, inode->i_ino,
+				     bytenr, &other_start, &other_end)) {
+			extent_end = other_end;
+			del_slot = path->slots[0] + 1;
+			del_nr++;
+			ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
+						leaf->start, leaf_owner,
+						leaf_gen, inode->i_ino, 0);
+			BUG_ON(ret);
+		}
+		other_start = 0;
+		other_end = start;
+		if (extent_mergeable(leaf, path->slots[0] - 1, inode->i_ino,
+				     bytenr, &other_start, &other_end)) {
+			key.offset = other_start;
+			del_slot = path->slots[0];
+			del_nr++;
+			ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
+						leaf->start, leaf_owner,
+						leaf_gen, inode->i_ino, 0);
+			BUG_ON(ret);
+		}
+		split_end = 0;
+		if (del_nr == 0) {
+			btrfs_set_file_extent_type(leaf, fi,
+						   BTRFS_FILE_EXTENT_REG);
+			goto done;
+		}
+
+		fi = btrfs_item_ptr(leaf, del_slot - 1,
+				    struct btrfs_file_extent_item);
+		btrfs_set_file_extent_type(leaf, fi, BTRFS_FILE_EXTENT_REG);
+		btrfs_set_file_extent_num_bytes(leaf, fi,
+						extent_end - key.offset);
+		btrfs_mark_buffer_dirty(leaf);
+
+		ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
+		BUG_ON(ret);
+		goto done;
+	} else if (split == start) {
+		if (locked_end < extent_end) {
+			ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
+					locked_end, extent_end - 1, GFP_NOFS);
+			if (!ret) {
+				btrfs_release_path(root, path);
+				lock_extent(&BTRFS_I(inode)->io_tree,
+					locked_end, extent_end - 1, GFP_NOFS);
+				locked_end = extent_end;
+				goto again;
+			}
+			locked_end = extent_end;
+		}
+		btrfs_set_file_extent_num_bytes(leaf, fi, split - key.offset);
+		extent_offset += split - key.offset;
+	} else  {
+		BUG_ON(key.offset != start);
+		btrfs_set_file_extent_offset(leaf, fi, extent_offset +
+					     split - key.offset);
+		btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - split);
+		key.offset = split;
+		btrfs_set_item_key_safe(trans, root, path, &key);
+		extent_end = split;
+	}
+
+	if (extent_end == end) {
+		split_end = 0;
+		extent_type = BTRFS_FILE_EXTENT_REG;
+	}
+	if (extent_end == end && split == start) {
+		other_start = end;
+		other_end = 0;
+		if (extent_mergeable(leaf, path->slots[0] + 1, inode->i_ino,
+				     bytenr, &other_start, &other_end)) {
+			path->slots[0]++;
+			fi = btrfs_item_ptr(leaf, path->slots[0],
+					    struct btrfs_file_extent_item);
+			key.offset = split;
+			btrfs_set_item_key_safe(trans, root, path, &key);
+			btrfs_set_file_extent_offset(leaf, fi, extent_offset);
+			btrfs_set_file_extent_num_bytes(leaf, fi,
+							other_end - split);
+			goto done;
+		}
+	}
+	if (extent_end == end && split == end) {
+		other_start = 0;
+		other_end = start;
+		if (extent_mergeable(leaf, path->slots[0] - 1 , inode->i_ino,
+				     bytenr, &other_start, &other_end)) {
+			path->slots[0]--;
+			fi = btrfs_item_ptr(leaf, path->slots[0],
+					    struct btrfs_file_extent_item);
+			btrfs_set_file_extent_num_bytes(leaf, fi, extent_end -
+							other_start);
+			goto done;
+		}
+	}
+
+	btrfs_mark_buffer_dirty(leaf);
+
+	orig_parent = leaf->start;
+	ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes,
+				   orig_parent, root->root_key.objectid,
+				   trans->transid, inode->i_ino);
+	BUG_ON(ret);
+	btrfs_release_path(root, path);
+
+	key.offset = start;
+	ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(*fi));
+	BUG_ON(ret);
+
+	leaf = path->nodes[0];
+	fi = btrfs_item_ptr(leaf, path->slots[0],
+			    struct btrfs_file_extent_item);
+	btrfs_set_file_extent_generation(leaf, fi, trans->transid);
+	btrfs_set_file_extent_type(leaf, fi, extent_type);
+	btrfs_set_file_extent_disk_bytenr(leaf, fi, bytenr);
+	btrfs_set_file_extent_disk_num_bytes(leaf, fi, num_bytes);
+	btrfs_set_file_extent_offset(leaf, fi, extent_offset);
+	btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - key.offset);
+	btrfs_set_file_extent_ram_bytes(leaf, fi, num_bytes);
+	btrfs_set_file_extent_compression(leaf, fi, 0);
+	btrfs_set_file_extent_encryption(leaf, fi, 0);
+	btrfs_set_file_extent_other_encoding(leaf, fi, 0);
+
+	if (orig_parent != leaf->start) {
+		ret = btrfs_update_extent_ref(trans, root, bytenr,
+					      orig_parent, leaf->start,
+					      root->root_key.objectid,
+					      trans->transid, inode->i_ino);
+		BUG_ON(ret);
+	}
+done:
+	btrfs_mark_buffer_dirty(leaf);
+	btrfs_release_path(root, path);
+	if (split_end && split == start) {
+		split = end;
+		goto again;
+	}
+	if (locked_end > end) {
+		unlock_extent(&BTRFS_I(inode)->io_tree, end, locked_end - 1,
+			      GFP_NOFS);
+	}
+	btrfs_free_path(path);
+	return 0;
+}
+
+/*
+ * this gets pages into the page cache and locks them down, it also properly
+ * waits for data=ordered extents to finish before allowing the pages to be
+ * modified.
+ */
+static int noinline prepare_pages(struct btrfs_root *root, struct file *file,
+			 struct page **pages, size_t num_pages,
+			 loff_t pos, unsigned long first_index,
+			 unsigned long last_index, size_t write_bytes)
+{
+	int i;
+	unsigned long index = pos >> PAGE_CACHE_SHIFT;
+	struct inode *inode = fdentry(file)->d_inode;
+	int err = 0;
+	u64 start_pos;
+	u64 last_pos;
+
+	start_pos = pos & ~((u64)root->sectorsize - 1);
+	last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
+
+	if (start_pos > inode->i_size) {
+		err = btrfs_cont_expand(inode, start_pos);
+		if (err)
+			return err;
+	}
+
+	memset(pages, 0, num_pages * sizeof(struct page *));
+again:
+	for (i = 0; i < num_pages; i++) {
+		pages[i] = grab_cache_page(inode->i_mapping, index + i);
+		if (!pages[i]) {
+			err = -ENOMEM;
+			BUG_ON(1);
+		}
+		wait_on_page_writeback(pages[i]);
+	}
+	if (start_pos < inode->i_size) {
+		struct btrfs_ordered_extent *ordered;
+		lock_extent(&BTRFS_I(inode)->io_tree,
+			    start_pos, last_pos - 1, GFP_NOFS);
+		ordered = btrfs_lookup_first_ordered_extent(inode, last_pos -1);
+		if (ordered &&
+		    ordered->file_offset + ordered->len > start_pos &&
+		    ordered->file_offset < last_pos) {
+			btrfs_put_ordered_extent(ordered);
+			unlock_extent(&BTRFS_I(inode)->io_tree,
+				      start_pos, last_pos - 1, GFP_NOFS);
+			for (i = 0; i < num_pages; i++) {
+				unlock_page(pages[i]);
+				page_cache_release(pages[i]);
+			}
+			btrfs_wait_ordered_range(inode, start_pos,
+						 last_pos - start_pos);
+			goto again;
+		}
+		if (ordered)
+			btrfs_put_ordered_extent(ordered);
+
+		clear_extent_bits(&BTRFS_I(inode)->io_tree, start_pos,
+				  last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC,
+				  GFP_NOFS);
+		unlock_extent(&BTRFS_I(inode)->io_tree,
+			      start_pos, last_pos - 1, GFP_NOFS);
+	}
+	for (i = 0; i < num_pages; i++) {
+		clear_page_dirty_for_io(pages[i]);
+		set_page_extent_mapped(pages[i]);
+		WARN_ON(!PageLocked(pages[i]));
+	}
+	return 0;
+}
+
+static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
+				size_t count, loff_t *ppos)
+{
+	loff_t pos;
+	loff_t start_pos;
+	ssize_t num_written = 0;
+	ssize_t err = 0;
+	int ret = 0;
+	struct inode *inode = fdentry(file)->d_inode;
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct page **pages = NULL;
+	int nrptrs;
+	struct page *pinned[2];
+	unsigned long first_index;
+	unsigned long last_index;
+	int will_write;
+
+	will_write = ((file->f_flags & O_SYNC) || IS_SYNC(inode) ||
+		      (file->f_flags & O_DIRECT));
+
+	nrptrs = min((count + PAGE_CACHE_SIZE - 1) / PAGE_CACHE_SIZE,
+		     PAGE_CACHE_SIZE / (sizeof(struct page *)));
+	pinned[0] = NULL;
+	pinned[1] = NULL;
+
+	pos = *ppos;
+	start_pos = pos;
+
+	vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
+	current->backing_dev_info = inode->i_mapping->backing_dev_info;
+	err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
+	if (err)
+		goto out_nolock;
+	if (count == 0)
+		goto out_nolock;
+
+	err = file_remove_suid(file);
+	if (err)
+		goto out_nolock;
+	file_update_time(file);
+
+	pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
+
+	mutex_lock(&inode->i_mutex);
+	first_index = pos >> PAGE_CACHE_SHIFT;
+	last_index = (pos + count) >> PAGE_CACHE_SHIFT;
+
+	/*
+	 * if this is a nodatasum mount, force summing off for the inode
+	 * all the time.  That way a later mount with summing on won't
+	 * get confused
+	 */
+	if (btrfs_test_opt(root, NODATASUM))
+		btrfs_set_flag(inode, NODATASUM);
+
+	/*
+	 * there are lots of better ways to do this, but this code
+	 * makes sure the first and last page in the file range are
+	 * up to date and ready for cow
+	 */
+	if ((pos & (PAGE_CACHE_SIZE - 1))) {
+		pinned[0] = grab_cache_page(inode->i_mapping, first_index);
+		if (!PageUptodate(pinned[0])) {
+			ret = btrfs_readpage(NULL, pinned[0]);
+			BUG_ON(ret);
+			wait_on_page_locked(pinned[0]);
+		} else {
+			unlock_page(pinned[0]);
+		}
+	}
+	if ((pos + count) & (PAGE_CACHE_SIZE - 1)) {
+		pinned[1] = grab_cache_page(inode->i_mapping, last_index);
+		if (!PageUptodate(pinned[1])) {
+			ret = btrfs_readpage(NULL, pinned[1]);
+			BUG_ON(ret);
+			wait_on_page_locked(pinned[1]);
+		} else {
+			unlock_page(pinned[1]);
+		}
+	}
+
+	while(count > 0) {
+		size_t offset = pos & (PAGE_CACHE_SIZE - 1);
+		size_t write_bytes = min(count, nrptrs *
+					(size_t)PAGE_CACHE_SIZE -
+					 offset);
+		size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
+					PAGE_CACHE_SHIFT;
+
+		WARN_ON(num_pages > nrptrs);
+		memset(pages, 0, sizeof(pages));
+
+		ret = btrfs_check_free_space(root, write_bytes, 0);
+		if (ret)
+			goto out;
+
+		ret = prepare_pages(root, file, pages, num_pages,
+				    pos, first_index, last_index,
+				    write_bytes);
+		if (ret)
+			goto out;
+
+		ret = btrfs_copy_from_user(pos, num_pages,
+					   write_bytes, pages, buf);
+		if (ret) {
+			btrfs_drop_pages(pages, num_pages);
+			goto out;
+		}
+
+		ret = dirty_and_release_pages(NULL, root, file, pages,
+					      num_pages, pos, write_bytes);
+		btrfs_drop_pages(pages, num_pages);
+		if (ret)
+			goto out;
+
+		if (will_write) {
+			btrfs_fdatawrite_range(inode->i_mapping, pos,
+					       pos + write_bytes - 1,
+					       WB_SYNC_NONE);
+		} else {
+			balance_dirty_pages_ratelimited_nr(inode->i_mapping,
+							   num_pages);
+			if (num_pages <
+			    (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
+				btrfs_btree_balance_dirty(root, 1);
+			btrfs_throttle(root);
+		}
+
+		buf += write_bytes;
+		count -= write_bytes;
+		pos += write_bytes;
+		num_written += write_bytes;
+
+		cond_resched();
+	}
+out:
+	mutex_unlock(&inode->i_mutex);
+
+out_nolock:
+	kfree(pages);
+	if (pinned[0])
+		page_cache_release(pinned[0]);
+	if (pinned[1])
+		page_cache_release(pinned[1]);
+	*ppos = pos;
+
+	if (num_written > 0 && will_write) {
+		struct btrfs_trans_handle *trans;
+
+		err = btrfs_wait_ordered_range(inode, start_pos, num_written);
+		if (err)
+			num_written = err;
+
+		if ((file->f_flags & O_SYNC) || IS_SYNC(inode)) {
+			trans = btrfs_start_transaction(root, 1);
+			ret = btrfs_log_dentry_safe(trans, root,
+						    file->f_dentry);
+			if (ret == 0) {
+				btrfs_sync_log(trans, root);
+				btrfs_end_transaction(trans, root);
+			} else {
+				btrfs_commit_transaction(trans, root);
+			}
+		}
+		if (file->f_flags & O_DIRECT) {
+			invalidate_mapping_pages(inode->i_mapping,
+			      start_pos >> PAGE_CACHE_SHIFT,
+			     (start_pos + num_written - 1) >> PAGE_CACHE_SHIFT);
+		}
+	}
+	current->backing_dev_info = NULL;
+	return num_written ? num_written : err;
+}
+
+int btrfs_release_file(struct inode * inode, struct file * filp)
+{
+	if (filp->private_data)
+		btrfs_ioctl_trans_end(filp);
+	return 0;
+}
+
+/*
+ * fsync call for both files and directories.  This logs the inode into
+ * the tree log instead of forcing full commits whenever possible.
+ *
+ * It needs to call filemap_fdatawait so that all ordered extent updates are
+ * in the metadata btree are up to date for copying to the log.
+ *
+ * It drops the inode mutex before doing the tree log commit.  This is an
+ * important optimization for directories because holding the mutex prevents
+ * new operations on the dir while we write to disk.
+ */
+int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
+{
+	struct inode *inode = dentry->d_inode;
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	int ret = 0;
+	struct btrfs_trans_handle *trans;
+
+	/*
+	 * check the transaction that last modified this inode
+	 * and see if its already been committed
+	 */
+	if (!BTRFS_I(inode)->last_trans)
+		goto out;
+
+	mutex_lock(&root->fs_info->trans_mutex);
+	if (BTRFS_I(inode)->last_trans <=
+	    root->fs_info->last_trans_committed) {
+		BTRFS_I(inode)->last_trans = 0;
+		mutex_unlock(&root->fs_info->trans_mutex);
+		goto out;
+	}
+	mutex_unlock(&root->fs_info->trans_mutex);
+
+	root->fs_info->tree_log_batch++;
+	filemap_fdatawait(inode->i_mapping);
+	root->fs_info->tree_log_batch++;
+
+	/*
+	 * ok we haven't committed the transaction yet, lets do a commit
+	 */
+	if (file->private_data)
+		btrfs_ioctl_trans_end(file);
+
+	trans = btrfs_start_transaction(root, 1);
+	if (!trans) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	ret = btrfs_log_dentry_safe(trans, root, file->f_dentry);
+	if (ret < 0) {
+		goto out;
+	}
+
+	/* we've logged all the items and now have a consistent
+	 * version of the file in the log.  It is possible that
+	 * someone will come in and modify the file, but that's
+	 * fine because the log is consistent on disk, and we
+	 * have references to all of the file's extents
+	 *
+	 * It is possible that someone will come in and log the
+	 * file again, but that will end up using the synchronization
+	 * inside btrfs_sync_log to keep things safe.
+	 */
+	mutex_unlock(&file->f_dentry->d_inode->i_mutex);
+
+	if (ret > 0) {
+		ret = btrfs_commit_transaction(trans, root);
+	} else {
+		btrfs_sync_log(trans, root);
+		ret = btrfs_end_transaction(trans, root);
+	}
+	mutex_lock(&file->f_dentry->d_inode->i_mutex);
+out:
+	return ret > 0 ? EIO : ret;
+}
+
+static struct vm_operations_struct btrfs_file_vm_ops = {
+	.fault		= filemap_fault,
+	.page_mkwrite	= btrfs_page_mkwrite,
+};
+
+static int btrfs_file_mmap(struct file	*filp, struct vm_area_struct *vma)
+{
+	vma->vm_ops = &btrfs_file_vm_ops;
+	file_accessed(filp);
+	return 0;
+}
+
+struct file_operations btrfs_file_operations = {
+	.llseek		= generic_file_llseek,
+	.read		= do_sync_read,
+	.aio_read       = generic_file_aio_read,
+	.splice_read	= generic_file_splice_read,
+	.write		= btrfs_file_write,
+	.mmap		= btrfs_file_mmap,
+	.open		= generic_file_open,
+	.release	= btrfs_release_file,
+	.fsync		= btrfs_sync_file,
+	.unlocked_ioctl	= btrfs_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= btrfs_ioctl,
+#endif
+};