drop unused dentry argument to ->fsync
[safe/jmp/linux-2.6] / fs / btrfs / file.c
index f155179..787b50a 100644 (file)
@@ -28,6 +28,7 @@
 #include <linux/writeback.h>
 #include <linux/statfs.h>
 #include <linux/compat.h>
+#include <linux/slab.h>
 #include "ctree.h"
 #include "disk-io.h"
 #include "transaction.h"
 static noinline int btrfs_copy_from_user(loff_t pos, int num_pages,
                                         int write_bytes,
                                         struct page **prepared_pages,
-                                        const char __user *buf)
+                                        struct iov_iter *i)
 {
-       long page_fault = 0;
-       int i;
+       size_t copied;
+       int pg = 0;
        int offset = pos & (PAGE_CACHE_SIZE - 1);
 
-       for (i = 0; i < num_pages && write_bytes > 0; i++, offset = 0) {
+       while (write_bytes > 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);
+               struct page *page = prepared_pages[pg];
+again:
+               if (unlikely(iov_iter_fault_in_readable(i, count)))
+                       return -EFAULT;
 
                /* Copy data from userspace to the current page */
-               kmap(page);
-               page_fault = __copy_from_user(page_address(page) + offset,
-                                             buf, count);
+               copied = iov_iter_copy_from_user(page, i, offset, count);
+
                /* Flush processor's dcache for this page */
                flush_dcache_page(page);
-               kunmap(page);
-               buf += count;
-               write_bytes -= count;
+               iov_iter_advance(i, copied);
+               write_bytes -= copied;
 
-               if (page_fault)
-                       break;
+               if (unlikely(copied == 0)) {
+                       count = min_t(size_t, PAGE_CACHE_SIZE - offset,
+                                     iov_iter_single_seg_count(i));
+                       goto again;
+               }
+
+               if (unlikely(copied < PAGE_CACHE_SIZE - offset)) {
+                       offset += copied;
+               } else {
+                       pg++;
+                       offset = 0;
+               }
        }
-       return page_fault ? -EFAULT : 0;
+       return 0;
 }
 
 /*
@@ -123,9 +134,9 @@ static noinline int dirty_and_release_pages(struct btrfs_trans_handle *trans,
                    root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
 
        end_of_last_block = start_pos + num_bytes - 1;
-       err = btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block);
-       if (err)
-               return err;
+       err = btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block,
+                                       NULL);
+       BUG_ON(err);
 
        for (i = 0; i < num_pages; i++) {
                struct page *p = pages[i];
@@ -140,7 +151,7 @@ static noinline int dirty_and_release_pages(struct btrfs_trans_handle *trans,
                 * at this time.
                 */
        }
-       return err;
+       return 0;
 }
 
 /*
@@ -179,18 +190,14 @@ int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
                }
                flags = em->flags;
                if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
-                       if (em->start <= start &&
-                           (!testend || em->start + em->len >= start + len)) {
+                       if (testend && em->start + em->len >= start + len) {
                                free_extent_map(em);
                                write_unlock(&em_tree->lock);
                                break;
                        }
-                       if (start < em->start) {
-                               len = em->start - start;
-                       } else {
+                       start = em->start + em->len;
+                       if (testend)
                                len = start + len - (em->start + em->len);
-                               start = em->start + em->len;
-                       }
                        free_extent_map(em);
                        write_unlock(&em_tree->lock);
                        continue;
@@ -265,324 +272,253 @@ int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
  * 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.
  */
-noinline int btrfs_drop_extents(struct btrfs_trans_handle *trans,
-                      struct btrfs_root *root, struct inode *inode,
-                      u64 start, u64 end, u64 locked_end,
-                      u64 inline_limit, u64 *hint_byte, int drop_cache)
+int btrfs_drop_extents(struct btrfs_trans_handle *trans, struct inode *inode,
+                      u64 start, u64 end, u64 *hint_byte, int drop_cache)
 {
-       u64 extent_end = 0;
-       u64 search_start = start;
-       u64 ram_bytes = 0;
-       u64 disk_bytenr = 0;
-       u64 orig_locked_end = locked_end;
-       u8 compression;
-       u8 encryption;
-       u16 other_encoding = 0;
+       struct btrfs_root *root = BTRFS_I(inode)->root;
        struct extent_buffer *leaf;
-       struct btrfs_file_extent_item *extent;
+       struct btrfs_file_extent_item *fi;
        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;
+       struct btrfs_key new_key;
+       u64 search_start = start;
+       u64 disk_bytenr = 0;
+       u64 num_bytes = 0;
+       u64 extent_offset = 0;
+       u64 extent_end = 0;
+       int del_nr = 0;
+       int del_slot = 0;
+       int extent_type;
        int recow;
        int ret;
 
-       inline_limit = 0;
        if (drop_cache)
                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]--;
+                       break;
+               if (ret > 0 && path->slots[0] > 0 && search_start == start) {
+                       leaf = path->nodes[0];
+                       btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
+                       if (key.objectid == inode->i_ino &&
+                           key.type == BTRFS_EXTENT_DATA_KEY)
+                               path->slots[0]--;
                }
+               ret = 0;
 next_slot:
-               keep = 0;
-               bookend = 0;
-               found_extent = 0;
-               found_inline = 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);
+               if (path->slots[0] >= btrfs_header_nritems(leaf)) {
+                       BUG_ON(del_nr > 0);
+                       ret = btrfs_next_leaf(root, path);
+                       if (ret < 0)
+                               break;
+                       if (ret > 0) {
+                               ret = 0;
+                               break;
                        }
+                       leaf = path->nodes[0];
+                       recow = 1;
+               }
+
+               btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+               if (key.objectid > inode->i_ino ||
+                   key.type > BTRFS_EXTENT_DATA_KEY || key.offset >= end)
+                       break;
+
+               fi = btrfs_item_ptr(leaf, path->slots[0],
+                                   struct btrfs_file_extent_item);
+               extent_type = btrfs_file_extent_type(leaf, fi);
+
+               if (extent_type == BTRFS_FILE_EXTENT_REG ||
+                   extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
+                       disk_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);
+                       extent_end = key.offset +
+                               btrfs_file_extent_num_bytes(leaf, fi);
+               } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
+                       extent_end = key.offset +
+                               btrfs_file_extent_inline_len(leaf, fi);
                } else {
+                       WARN_ON(1);
                        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]++;
-                       }
+               if (extent_end <= search_start) {
+                       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));
-               }
-
-               if (end < extent_end && end >= key.offset) {
-                       bookend = 1;
-                       if (found_inline && start <= key.offset)
-                               keep = 1;
+               search_start = max(key.offset, start);
+               if (recow) {
+                       btrfs_release_path(root, path);
+                       continue;
                }
 
-               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;
+               /*
+                *     | - range to drop - |
+                *  | -------- extent -------- |
+                */
+               if (start > key.offset && end < extent_end) {
+                       BUG_ON(del_nr > 0);
+                       BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
+
+                       memcpy(&new_key, &key, sizeof(new_key));
+                       new_key.offset = start;
+                       ret = btrfs_duplicate_item(trans, root, path,
+                                                  &new_key);
+                       if (ret == -EAGAIN) {
+                               btrfs_release_path(root, path);
+                               continue;
                        }
-                       disk_bytenr = le64_to_cpu(old.disk_bytenr);
-                       if (disk_bytenr != 0) {
+                       if (ret < 0)
+                               break;
+
+                       leaf = path->nodes[0];
+                       fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
+                                           struct btrfs_file_extent_item);
+                       btrfs_set_file_extent_num_bytes(leaf, fi,
+                                                       start - key.offset);
+
+                       fi = btrfs_item_ptr(leaf, path->slots[0],
+                                           struct btrfs_file_extent_item);
+
+                       extent_offset += start - key.offset;
+                       btrfs_set_file_extent_offset(leaf, fi, extent_offset);
+                       btrfs_set_file_extent_num_bytes(leaf, fi,
+                                                       extent_end - start);
+                       btrfs_mark_buffer_dirty(leaf);
+
+                       if (disk_bytenr > 0) {
                                ret = btrfs_inc_extent_ref(trans, root,
-                                          disk_bytenr,
-                                          le64_to_cpu(old.disk_num_bytes), 0,
-                                          root->root_key.objectid,
-                                          key.objectid, key.offset -
-                                          le64_to_cpu(old.offset));
+                                               disk_bytenr, num_bytes, 0,
+                                               root->root_key.objectid,
+                                               new_key.objectid,
+                                               start - extent_offset);
                                BUG_ON(ret);
+                               *hint_byte = disk_bytenr;
                        }
+                       key.offset = start;
                }
+               /*
+                *  | ---- range to drop ----- |
+                *      | -------- extent -------- |
+                */
+               if (start <= key.offset && end < extent_end) {
+                       BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
 
-               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);
-                               }
-                               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);
-                               }
+                       memcpy(&new_key, &key, sizeof(new_key));
+                       new_key.offset = end;
+                       btrfs_set_item_key_safe(trans, root, path, &new_key);
+
+                       extent_offset += end - key.offset;
+                       btrfs_set_file_extent_offset(leaf, fi, extent_offset);
+                       btrfs_set_file_extent_num_bytes(leaf, fi,
+                                                       extent_end - end);
+                       btrfs_mark_buffer_dirty(leaf);
+                       if (disk_bytenr > 0) {
+                               inode_sub_bytes(inode, end - key.offset);
+                               *hint_byte = disk_bytenr;
                        }
+                       break;
                }
-               /* 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);
-                       path->leave_spinning = 1;
-                       ret = btrfs_insert_empty_item(trans, root, path, &ins,
-                                                     sizeof(*extent));
-                       BUG_ON(ret);
+               search_start = extent_end;
+               /*
+                *       | ---- range to drop ----- |
+                *  | -------- extent -------- |
+                */
+               if (start > key.offset && end >= extent_end) {
+                       BUG_ON(del_nr > 0);
+                       BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
 
-                       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);
+                       btrfs_set_file_extent_num_bytes(leaf, fi,
+                                                       start - key.offset);
+                       btrfs_mark_buffer_dirty(leaf);
+                       if (disk_bytenr > 0) {
+                               inode_sub_bytes(inode, extent_end - start);
+                               *hint_byte = disk_bytenr;
+                       }
+                       if (end == extent_end)
+                               break;
 
-                       /*
-                        * 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_unlock_up_safe(path, 1);
-                       btrfs_mark_buffer_dirty(path->nodes[0]);
-                       btrfs_set_lock_blocking(path->nodes[0]);
-
-                       path->leave_spinning = 0;
-                       btrfs_release_path(root, path);
-                       if (disk_bytenr != 0)
-                               inode_add_bytes(inode, extent_end - end);
+                       path->slots[0]++;
+                       goto next_slot;
                }
 
-               if (found_extent && !keep) {
-                       u64 old_disk_bytenr = le64_to_cpu(old.disk_bytenr);
+               /*
+                *  | ---- range to drop ----- |
+                *    | ------ extent ------ |
+                */
+               if (start <= key.offset && end >= extent_end) {
+                       if (del_nr == 0) {
+                               del_slot = path->slots[0];
+                               del_nr = 1;
+                       } else {
+                               BUG_ON(del_slot + del_nr != path->slots[0]);
+                               del_nr++;
+                       }
 
-                       if (old_disk_bytenr != 0) {
+                       if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
                                inode_sub_bytes(inode,
-                                               le64_to_cpu(old.num_bytes));
+                                               extent_end - key.offset);
+                               extent_end = ALIGN(extent_end,
+                                                  root->sectorsize);
+                       } else if (disk_bytenr > 0) {
                                ret = btrfs_free_extent(trans, root,
-                                               old_disk_bytenr,
-                                               le64_to_cpu(old.disk_num_bytes),
-                                               0, root->root_key.objectid,
+                                               disk_bytenr, num_bytes, 0,
+                                               root->root_key.objectid,
                                                key.objectid, key.offset -
-                                               le64_to_cpu(old.offset));
+                                               extent_offset);
                                BUG_ON(ret);
-                               *hint_byte = old_disk_bytenr;
+                               inode_sub_bytes(inode,
+                                               extent_end - key.offset);
+                               *hint_byte = disk_bytenr;
                        }
-               }
 
-               if (search_start >= end) {
-                       ret = 0;
-                       goto out;
+                       if (end == extent_end)
+                               break;
+
+                       if (path->slots[0] + 1 < btrfs_header_nritems(leaf)) {
+                               path->slots[0]++;
+                               goto next_slot;
+                       }
+
+                       ret = btrfs_del_items(trans, root, path, del_slot,
+                                             del_nr);
+                       BUG_ON(ret);
+
+                       del_nr = 0;
+                       del_slot = 0;
+
+                       btrfs_release_path(root, path);
+                       continue;
                }
+
+               BUG_ON(1);
        }
-out:
-       btrfs_free_path(path);
-       if (locked_end > orig_locked_end) {
-               unlock_extent(&BTRFS_I(inode)->io_tree, orig_locked_end,
-                             locked_end - 1, GFP_NOFS);
+
+       if (del_nr > 0) {
+               ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
+               BUG_ON(ret);
        }
+
+       btrfs_free_path(path);
        return ret;
 }
 
 static int extent_mergeable(struct extent_buffer *leaf, int slot,
-                           u64 objectid, u64 bytenr, u64 *start, u64 *end)
+                           u64 objectid, u64 bytenr, u64 orig_offset,
+                           u64 *start, u64 *end)
 {
        struct btrfs_file_extent_item *fi;
        struct btrfs_key key;
@@ -598,6 +534,7 @@ static int extent_mergeable(struct extent_buffer *leaf, int slot,
        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_offset(leaf, fi) != key.offset - orig_offset ||
            btrfs_file_extent_compression(leaf, fi) ||
            btrfs_file_extent_encryption(leaf, fi) ||
            btrfs_file_extent_other_encoding(leaf, fi))
@@ -620,23 +557,24 @@ static int extent_mergeable(struct extent_buffer *leaf, int slot,
  * 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 btrfs_root *root = BTRFS_I(inode)->root;
        struct extent_buffer *leaf;
        struct btrfs_path *path;
        struct btrfs_file_extent_item *fi;
        struct btrfs_key key;
+       struct btrfs_key new_key;
        u64 bytenr;
        u64 num_bytes;
        u64 extent_end;
        u64 orig_offset;
        u64 other_start;
        u64 other_end;
-       u64 split = start;
-       u64 locked_end = end;
-       int extent_type;
-       int split_end = 1;
+       u64 split;
+       int del_nr = 0;
+       int del_slot = 0;
+       int recow;
        int ret;
 
        btrfs_drop_extent_cache(inode, start, end - 1, 0);
@@ -644,12 +582,11 @@ int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
        path = btrfs_alloc_path();
        BUG_ON(!path);
 again:
+       recow = 0;
+       split = start;
        key.objectid = inode->i_ino;
        key.type = BTRFS_EXTENT_DATA_KEY;
-       if (split == start)
-               key.offset = split;
-       else
-               key.offset = split - 1;
+       key.offset = split;
 
        ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
        if (ret > 0 && path->slots[0] > 0)
@@ -661,159 +598,158 @@ again:
               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);
+       BUG_ON(btrfs_file_extent_type(leaf, fi) !=
+              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);
        orig_offset = key.offset - btrfs_file_extent_offset(leaf, fi);
+       memcpy(&new_key, &key, sizeof(new_key));
 
-       if (key.offset == start)
-               split = end;
-
-       if (key.offset == start && extent_end == end) {
-               int del_nr = 0;
-               int del_slot = 0;
-               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,
-                                               0, root->root_key.objectid,
-                                               inode->i_ino, orig_offset);
-                       BUG_ON(ret);
-               }
+       if (start == key.offset && end < extent_end) {
                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,
-                                               0, root->root_key.objectid,
-                                               inode->i_ino, orig_offset);
-                       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 release;
-       } 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;
+               if (extent_mergeable(leaf, path->slots[0] - 1,
+                                    inode->i_ino, bytenr, orig_offset,
+                                    &other_start, &other_end)) {
+                       new_key.offset = end;
+                       btrfs_set_item_key_safe(trans, root, path, &new_key);
+                       fi = btrfs_item_ptr(leaf, path->slots[0],
+                                           struct btrfs_file_extent_item);
+                       btrfs_set_file_extent_num_bytes(leaf, fi,
+                                                       extent_end - end);
+                       btrfs_set_file_extent_offset(leaf, fi,
+                                                    end - orig_offset);
+                       fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
+                                           struct btrfs_file_extent_item);
+                       btrfs_set_file_extent_num_bytes(leaf, fi,
+                                                       end - other_start);
+                       btrfs_mark_buffer_dirty(leaf);
+                       goto out;
                }
-               btrfs_set_file_extent_num_bytes(leaf, fi, split - key.offset);
-       } else  {
-               BUG_ON(key.offset != start);
-               key.offset = split;
-               btrfs_set_file_extent_offset(leaf, fi, key.offset -
-                                            orig_offset);
-               btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - 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) {
+       if (start > key.offset && end == extent_end) {
                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]++;
+               if (extent_mergeable(leaf, path->slots[0] + 1,
+                                    inode->i_ino, bytenr, orig_offset,
+                                    &other_start, &other_end)) {
                        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, key.offset -
-                                                    orig_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]--;
+                                                       start - key.offset);
+                       path->slots[0]++;
+                       new_key.offset = start;
+                       btrfs_set_item_key_safe(trans, root, path, &new_key);
+
                        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_set_file_extent_num_bytes(leaf, fi,
+                                                       other_end - start);
+                       btrfs_set_file_extent_offset(leaf, fi,
+                                                    start - orig_offset);
+                       btrfs_mark_buffer_dirty(leaf);
+                       goto out;
                }
        }
 
-       btrfs_mark_buffer_dirty(leaf);
+       while (start > key.offset || end < extent_end) {
+               if (key.offset == start)
+                       split = end;
+
+               new_key.offset = split;
+               ret = btrfs_duplicate_item(trans, root, path, &new_key);
+               if (ret == -EAGAIN) {
+                       btrfs_release_path(root, path);
+                       goto again;
+               }
+               BUG_ON(ret < 0);
 
-       ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, 0,
-                                  root->root_key.objectid,
-                                  inode->i_ino, orig_offset);
-       BUG_ON(ret);
-       btrfs_release_path(root, path);
+               leaf = path->nodes[0];
+               fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
+                                   struct btrfs_file_extent_item);
+               btrfs_set_file_extent_num_bytes(leaf, fi,
+                                               split - key.offset);
 
-       key.offset = start;
-       ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(*fi));
-       BUG_ON(ret);
+               fi = btrfs_item_ptr(leaf, path->slots[0],
+                                   struct btrfs_file_extent_item);
 
-       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, key.offset - orig_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);
-done:
-       btrfs_mark_buffer_dirty(leaf);
-
-release:
-       btrfs_release_path(root, path);
-       if (split_end && split == start) {
-               split = end;
-               goto again;
+               btrfs_set_file_extent_offset(leaf, fi, split - orig_offset);
+               btrfs_set_file_extent_num_bytes(leaf, fi,
+                                               extent_end - split);
+               btrfs_mark_buffer_dirty(leaf);
+
+               ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, 0,
+                                          root->root_key.objectid,
+                                          inode->i_ino, orig_offset);
+               BUG_ON(ret);
+
+               if (split == start) {
+                       key.offset = start;
+               } else {
+                       BUG_ON(start != key.offset);
+                       path->slots[0]--;
+                       extent_end = end;
+               }
+               recow = 1;
        }
-       if (locked_end > end) {
-               unlock_extent(&BTRFS_I(inode)->io_tree, end, locked_end - 1,
-                             GFP_NOFS);
+
+       other_start = end;
+       other_end = 0;
+       if (extent_mergeable(leaf, path->slots[0] + 1,
+                            inode->i_ino, bytenr, orig_offset,
+                            &other_start, &other_end)) {
+               if (recow) {
+                       btrfs_release_path(root, path);
+                       goto again;
+               }
+               extent_end = other_end;
+               del_slot = path->slots[0] + 1;
+               del_nr++;
+               ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
+                                       0, root->root_key.objectid,
+                                       inode->i_ino, orig_offset);
+               BUG_ON(ret);
        }
+       other_start = 0;
+       other_end = start;
+       if (extent_mergeable(leaf, path->slots[0] - 1,
+                            inode->i_ino, bytenr, orig_offset,
+                            &other_start, &other_end)) {
+               if (recow) {
+                       btrfs_release_path(root, path);
+                       goto again;
+               }
+               key.offset = other_start;
+               del_slot = path->slots[0];
+               del_nr++;
+               ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
+                                       0, root->root_key.objectid,
+                                       inode->i_ino, orig_offset);
+               BUG_ON(ret);
+       }
+       if (del_nr == 0) {
+               fi = btrfs_item_ptr(leaf, path->slots[0],
+                          struct btrfs_file_extent_item);
+               btrfs_set_file_extent_type(leaf, fi,
+                                          BTRFS_FILE_EXTENT_REG);
+               btrfs_mark_buffer_dirty(leaf);
+       } else {
+               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);
+       }
+out:
        btrfs_free_path(path);
        return 0;
 }
@@ -828,6 +764,7 @@ static noinline int prepare_pages(struct btrfs_root *root, struct file *file,
                         loff_t pos, unsigned long first_index,
                         unsigned long last_index, size_t write_bytes)
 {
+       struct extent_state *cached_state = NULL;
        int i;
        unsigned long index = pos >> PAGE_CACHE_SHIFT;
        struct inode *inode = fdentry(file)->d_inode;
@@ -856,16 +793,18 @@ again:
        }
        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);
+               lock_extent_bits(&BTRFS_I(inode)->io_tree,
+                                start_pos, last_pos - 1, 0, &cached_state,
+                                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);
+                       unlock_extent_cached(&BTRFS_I(inode)->io_tree,
+                                            start_pos, last_pos - 1,
+                                            &cached_state, GFP_NOFS);
                        for (i = 0; i < num_pages; i++) {
                                unlock_page(pages[i]);
                                page_cache_release(pages[i]);
@@ -877,11 +816,13 @@ 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,
+               clear_extent_bit(&BTRFS_I(inode)->io_tree, start_pos,
+                                 last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC |
+                                 EXTENT_DO_ACCOUNTING, 0, 0, &cached_state,
                                  GFP_NOFS);
-               unlock_extent(&BTRFS_I(inode)->io_tree,
-                             start_pos, last_pos - 1, GFP_NOFS);
+               unlock_extent_cached(&BTRFS_I(inode)->io_tree,
+                                    start_pos, last_pos - 1, &cached_state,
+                                    GFP_NOFS);
        }
        for (i = 0; i < num_pages; i++) {
                clear_page_dirty_for_io(pages[i]);
@@ -891,45 +832,46 @@ again:
        return 0;
 }
 
-static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
-                               size_t count, loff_t *ppos)
+static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
+                                   const struct iovec *iov,
+                                   unsigned long nr_segs, loff_t pos)
 {
-       loff_t pos;
+       struct file *file = iocb->ki_filp;
+       struct inode *inode = fdentry(file)->d_inode;
+       struct btrfs_root *root = BTRFS_I(inode)->root;
+       struct page *pinned[2];
+       struct page **pages = NULL;
+       struct iov_iter i;
+       loff_t *ppos = &iocb->ki_pos;
        loff_t start_pos;
        ssize_t num_written = 0;
        ssize_t err = 0;
+       size_t count;
+       size_t ocount;
        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;
+       int buffered = 0;
 
-       will_write = ((file->f_flags & O_SYNC) || IS_SYNC(inode) ||
+       will_write = ((file->f_flags & O_DSYNC) || 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);
 
-       /* do the reserve before the mutex lock in case we have to do some
-        * flushing.  We wouldn't deadlock, but this is more polite.
-        */
-       err = btrfs_reserve_metadata_for_delalloc(root, inode, 1);
-       if (err)
-               goto out_nolock;
-
        mutex_lock(&inode->i_mutex);
 
+       err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
+       if (err)
+               goto out;
+       count = ocount;
+
        current->backing_dev_info = inode->i_mapping->backing_dev_info;
        err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
        if (err)
@@ -943,15 +885,53 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
                goto out;
 
        file_update_time(file);
+       BTRFS_I(inode)->sequence++;
+
+       if (unlikely(file->f_flags & O_DIRECT)) {
+               num_written = generic_file_direct_write(iocb, iov, &nr_segs,
+                                                       pos, ppos, count,
+                                                       ocount);
+               /*
+                * the generic O_DIRECT will update in-memory i_size after the
+                * DIOs are done.  But our endio handlers that update the on
+                * disk i_size never update past the in memory i_size.  So we
+                * need one more update here to catch any additions to the
+                * file
+                */
+               if (inode->i_size != BTRFS_I(inode)->disk_i_size) {
+                       btrfs_ordered_update_i_size(inode, inode->i_size, NULL);
+                       mark_inode_dirty(inode);
+               }
+
+               if (num_written < 0) {
+                       ret = num_written;
+                       num_written = 0;
+                       goto out;
+               } else if (num_written == count) {
+                       /* pick up pos changes done by the generic code */
+                       pos = *ppos;
+                       goto out;
+               }
+               /*
+                * We are going to do buffered for the rest of the range, so we
+                * need to make sure to invalidate the buffered pages when we're
+                * done.
+                */
+               buffered = 1;
+               pos += num_written;
+       }
 
+       iov_iter_init(&i, iov, nr_segs, count, num_written);
+       nrptrs = min((iov_iter_count(&i) + PAGE_CACHE_SIZE - 1) /
+                    PAGE_CACHE_SIZE, PAGE_CACHE_SIZE /
+                    (sizeof(struct page *)));
        pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
 
        /* generic_write_checks can change our pos */
        start_pos = pos;
 
-       BTRFS_I(inode)->sequence++;
        first_index = pos >> PAGE_CACHE_SHIFT;
-       last_index = (pos + count) >> PAGE_CACHE_SHIFT;
+       last_index = (pos + iov_iter_count(&i)) >> PAGE_CACHE_SHIFT;
 
        /*
         * there are lots of better ways to do this, but this code
@@ -968,7 +948,7 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
                        unlock_page(pinned[0]);
                }
        }
-       if ((pos + count) & (PAGE_CACHE_SIZE - 1)) {
+       if ((pos + iov_iter_count(&i)) & (PAGE_CACHE_SIZE - 1)) {
                pinned[1] = grab_cache_page(inode->i_mapping, last_index);
                if (!PageUptodate(pinned[1])) {
                        ret = btrfs_readpage(NULL, pinned[1]);
@@ -979,10 +959,10 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
                }
        }
 
-       while (count > 0) {
+       while (iov_iter_count(&i) > 0) {
                size_t offset = pos & (PAGE_CACHE_SIZE - 1);
-               size_t write_bytes = min(count, nrptrs *
-                                       (size_t)PAGE_CACHE_SIZE -
+               size_t write_bytes = min(iov_iter_count(&i),
+                                        nrptrs * (size_t)PAGE_CACHE_SIZE -
                                         offset);
                size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
                                        PAGE_CACHE_SHIFT;
@@ -990,7 +970,7 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
                WARN_ON(num_pages > nrptrs);
                memset(pages, 0, sizeof(struct page *) * nrptrs);
 
-               ret = btrfs_check_data_free_space(root, inode, write_bytes);
+               ret = btrfs_delalloc_reserve_space(inode, write_bytes);
                if (ret)
                        goto out;
 
@@ -998,33 +978,26 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
                                    pos, first_index, last_index,
                                    write_bytes);
                if (ret) {
-                       btrfs_free_reserved_data_space(root, inode,
-                                                      write_bytes);
+                       btrfs_delalloc_release_space(inode, write_bytes);
                        goto out;
                }
 
                ret = btrfs_copy_from_user(pos, num_pages,
-                                          write_bytes, pages, buf);
-               if (ret) {
-                       btrfs_free_reserved_data_space(root, inode,
-                                                      write_bytes);
-                       btrfs_drop_pages(pages, num_pages);
-                       goto out;
+                                          write_bytes, pages, &i);
+               if (ret == 0) {
+                       dirty_and_release_pages(NULL, root, file, pages,
+                                               num_pages, pos, write_bytes);
                }
 
-               ret = dirty_and_release_pages(NULL, root, file, pages,
-                                             num_pages, pos, write_bytes);
                btrfs_drop_pages(pages, num_pages);
                if (ret) {
-                       btrfs_free_reserved_data_space(root, inode,
-                                                      write_bytes);
+                       btrfs_delalloc_release_space(inode, write_bytes);
                        goto out;
                }
 
                if (will_write) {
-                       btrfs_fdatawrite_range(inode->i_mapping, pos,
-                                              pos + write_bytes - 1,
-                                              WB_SYNC_ALL);
+                       filemap_fdatawrite_range(inode->i_mapping, pos,
+                                                pos + write_bytes - 1);
                } else {
                        balance_dirty_pages_ratelimited_nr(inode->i_mapping,
                                                           num_pages);
@@ -1034,8 +1007,6 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
                        btrfs_throttle(root);
                }
 
-               buf += write_bytes;
-               count -= write_bytes;
                pos += write_bytes;
                num_written += write_bytes;
 
@@ -1045,9 +1016,7 @@ out:
        mutex_unlock(&inode->i_mutex);
        if (ret)
                err = ret;
-       btrfs_unreserve_metadata_for_delalloc(root, inode, 1);
 
-out_nolock:
        kfree(pages);
        if (pinned[0])
                page_cache_release(pinned[0]);
@@ -1076,8 +1045,8 @@ out_nolock:
                if (err)
                        num_written = err;
 
-               if ((file->f_flags & O_SYNC) || IS_SYNC(inode)) {
-                       trans = btrfs_start_transaction(root, 1);
+               if ((file->f_flags & O_DSYNC) || IS_SYNC(inode)) {
+                       trans = btrfs_start_transaction(root, 0);
                        ret = btrfs_log_dentry_safe(trans, root,
                                                    file->f_dentry);
                        if (ret == 0) {
@@ -1086,11 +1055,13 @@ out_nolock:
                                        btrfs_end_transaction(trans, root);
                                else
                                        btrfs_commit_transaction(trans, root);
-                       } else {
+                       } else if (ret != BTRFS_NO_LOG_SYNC) {
                                btrfs_commit_transaction(trans, root);
+                       } else {
+                               btrfs_end_transaction(trans, root);
                        }
                }
-               if (file->f_flags & O_DIRECT) {
+               if (file->f_flags & O_DIRECT && buffered) {
                        invalidate_mapping_pages(inode->i_mapping,
                              start_pos >> PAGE_CACHE_SHIFT,
                             (start_pos + num_written - 1) >> PAGE_CACHE_SHIFT);
@@ -1130,13 +1101,21 @@ int btrfs_release_file(struct inode *inode, struct file *filp)
  * 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)
+int btrfs_sync_file(struct file *file, int datasync)
 {
+       struct dentry *dentry = file->f_path.dentry;
        struct inode *inode = dentry->d_inode;
        struct btrfs_root *root = BTRFS_I(inode)->root;
        int ret = 0;
        struct btrfs_trans_handle *trans;
 
+
+       /* we wait first, since the writeback may change the inode */
+       root->log_batch++;
+       /* the VFS called filemap_fdatawrite for us */
+       btrfs_wait_ordered_range(inode, 0, (u64)-1);
+       root->log_batch++;
+
        /*
         * check the transaction that last modified this inode
         * and see if its already been committed
@@ -1144,6 +1123,11 @@ int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
        if (!BTRFS_I(inode)->last_trans)
                goto out;
 
+       /*
+        * if the last transaction that changed this file was before
+        * the current transaction, we can bail out now without any
+        * syncing
+        */
        mutex_lock(&root->fs_info->trans_mutex);
        if (BTRFS_I(inode)->last_trans <=
            root->fs_info->last_trans_committed) {
@@ -1153,22 +1137,15 @@ int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
        }
        mutex_unlock(&root->fs_info->trans_mutex);
 
-       root->log_batch++;
-       filemap_fdatawrite(inode->i_mapping);
-       btrfs_wait_ordered_range(inode, 0, (u64)-1);
-       root->log_batch++;
-
-       if (datasync && !(inode->i_state & I_DIRTY_PAGES))
-               goto out;
        /*
         * ok we haven't committed the transaction yet, lets do a commit
         */
        if (file && file->private_data)
                btrfs_ioctl_trans_end(file);
 
-       trans = btrfs_start_transaction(root, 1);
-       if (!trans) {
-               ret = -ENOMEM;
+       trans = btrfs_start_transaction(root, 0);
+       if (IS_ERR(trans)) {
+               ret = PTR_ERR(trans);
                goto out;
        }
 
@@ -1188,21 +1165,25 @@ int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
         */
        mutex_unlock(&dentry->d_inode->i_mutex);
 
-       if (ret > 0) {
-               ret = btrfs_commit_transaction(trans, root);
-       } else {
-               ret = btrfs_sync_log(trans, root);
-               if (ret == 0)
-                       ret = btrfs_end_transaction(trans, root);
-               else
+       if (ret != BTRFS_NO_LOG_SYNC) {
+               if (ret > 0) {
                        ret = btrfs_commit_transaction(trans, root);
+               } else {
+                       ret = btrfs_sync_log(trans, root);
+                       if (ret == 0)
+                               ret = btrfs_end_transaction(trans, root);
+                       else
+                               ret = btrfs_commit_transaction(trans, root);
+               }
+       } else {
+               ret = btrfs_end_transaction(trans, root);
        }
        mutex_lock(&dentry->d_inode->i_mutex);
 out:
-       return ret > 0 ? EIO : ret;
+       return ret > 0 ? -EIO : ret;
 }
 
-static struct vm_operations_struct btrfs_file_vm_ops = {
+static const struct vm_operations_struct btrfs_file_vm_ops = {
        .fault          = filemap_fault,
        .page_mkwrite   = btrfs_page_mkwrite,
 };
@@ -1214,12 +1195,12 @@ static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
        return 0;
 }
 
-struct file_operations btrfs_file_operations = {
+const 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,
+       .aio_write      = btrfs_file_aio_write,
        .mmap           = btrfs_file_mmap,
        .open           = generic_file_open,
        .release        = btrfs_release_file,