Btrfs: many file_write fixes, inline data

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 437 insertions, 116 deletions

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 583cd87a62e2..1b286bb26f12 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -317,19 +317,22 @@ static int btrfs_truncate_in_trans(struct btrfs_trans_handle *trans,
                         break;
                 if (btrfs_disk_key_offset(found_key) < inode->i_size)
                         break;
+                found_extent = 0;
                 if (btrfs_disk_key_type(found_key) == BTRFS_EXTENT_DATA_KEY) {
                         fi = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]),
                                             path->slots[0],
                                             struct btrfs_file_extent_item);
-                        extent_start = btrfs_file_extent_disk_blocknr(fi);
-                        extent_num_blocks =
-                                btrfs_file_extent_disk_num_blocks(fi);
-                        /* FIXME blocksize != 4096 */
-                        inode->i_blocks -=
-                                btrfs_file_extent_num_blocks(fi) << 3;
-                        found_extent = 1;
-                } else {
-                        found_extent = 0;
+                        if (btrfs_file_extent_type(fi) !=
+                            BTRFS_FILE_EXTENT_INLINE) {
+                                extent_start =
+                                        btrfs_file_extent_disk_blocknr(fi);
+                                extent_num_blocks =
+                                        btrfs_file_extent_disk_num_blocks(fi);
+                                /* FIXME blocksize != 4096 */
+                                inode->i_blocks -=
+                                        btrfs_file_extent_num_blocks(fi) << 3;
+                                found_extent = 1;
+                        }
                 }
                 ret = btrfs_del_item(trans, root, path);
                 BUG_ON(ret);
@@ -1010,9 +1013,9 @@ static int btrfs_get_block_lock(struct inode *inode, sector_t iblock,
         u64 extent_start = 0;
         u64 extent_end = 0;
         u64 objectid = inode->i_ino;
+        u32 found_type;
         struct btrfs_path *path;
         struct btrfs_root *root = BTRFS_I(inode)->root;
-        struct btrfs_trans_handle *trans = NULL;
         struct btrfs_file_extent_item *item;
         struct btrfs_leaf *leaf;
         struct btrfs_disk_key *found_key;
@@ -1021,13 +1024,12 @@ static int btrfs_get_block_lock(struct inode *inode, sector_t iblock,
         BUG_ON(!path);
         btrfs_init_path(path);
         if (create) {
-                trans = btrfs_start_transaction(root, 1);
                 WARN_ON(1);
         }
 
-        ret = btrfs_lookup_file_extent(trans, root, path,
+        ret = btrfs_lookup_file_extent(NULL, root, path,
                                        inode->i_ino,
-                                       iblock << inode->i_blkbits, create);
+                                       iblock << inode->i_blkbits, 0);
         if (ret < 0) {
                 err = ret;
                 goto out;
@@ -1036,7 +1038,7 @@ static int btrfs_get_block_lock(struct inode *inode, sector_t iblock,
         if (ret != 0) {
                 if (path->slots[0] == 0) {
                         btrfs_release_path(root, path);
-                        goto allocate;
+                        goto out;
                 }
                 path->slots[0]--;
         }
@@ -1047,73 +1049,51 @@ static int btrfs_get_block_lock(struct inode *inode, sector_t iblock,
         blocknr = btrfs_file_extent_disk_blocknr(item);
         blocknr += btrfs_file_extent_offset(item);
 
-        /* exact match found, use it, FIXME, deal with extents
-         * other than the page size
-         */
-        if (0 && ret == 0) {
-                err = 0;
-                if (create &&
-                    btrfs_file_extent_generation(item) != trans->transid) {
-                        struct btrfs_key ins;
-                        ret = btrfs_alloc_extent(trans, root, 1,
-                                                 blocknr, (u64)-1, &ins);
-                        BUG_ON(ret);
-                        btrfs_set_file_extent_disk_blocknr(item, ins.objectid);
-                        mark_buffer_dirty(path->nodes[0]);
-                        ret = btrfs_free_extent(trans, root,
-                                                blocknr, 1, 0);
-                        BUG_ON(ret);
-                        blocknr = ins.objectid;
-
-                }
-                btrfs_map_bh_to_logical(root, result, blocknr);
-                goto out;
-        }
-
         /* are we inside the extent that was found? */
         found_key = &leaf->items[path->slots[0]].key;
+        found_type = btrfs_disk_key_type(found_key);
         if (btrfs_disk_key_objectid(found_key) != objectid ||
-            btrfs_disk_key_type(found_key) != BTRFS_EXTENT_DATA_KEY) {
+            found_type != BTRFS_EXTENT_DATA_KEY) {
                 extent_end = 0;
                 extent_start = 0;
                 btrfs_release_path(root, path);
-                goto allocate;
-        }
-
-        extent_start = btrfs_disk_key_offset(&leaf->items[path->slots[0]].key);
-        extent_start = extent_start >> inode->i_blkbits;
-        extent_end = extent_start + btrfs_file_extent_num_blocks(item);
-        if (iblock >= extent_start && iblock < extent_end) {
-                err = 0;
-                btrfs_map_bh_to_logical(root, result, blocknr + iblock -
-                                        extent_start);
-                goto out;
-        }
-allocate:
-        /* ok, create a new extent */
-        if (!create) {
-                err = 0;
                 goto out;
         }
-#if 0
-        ret = btrfs_alloc_file_extent(trans, root, objectid,
-                                      iblock << inode->i_blkbits,
-                                      1, extent_end, &blocknr);
-        if (ret) {
-                err = ret;
-                goto out;
+        found_type = btrfs_file_extent_type(item);
+        extent_start = btrfs_disk_key_offset(&leaf->items[path->slots[0]].key);
+        if (found_type == BTRFS_FILE_EXTENT_REG) {
+                extent_start = extent_start >> inode->i_blkbits;
+                extent_end = extent_start + btrfs_file_extent_num_blocks(item);
+                if (iblock >= extent_start && iblock < extent_end) {
+                        err = 0;
+                        btrfs_map_bh_to_logical(root, result, blocknr +
+                                                iblock - extent_start);
+                        goto out;
+                }
+        } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
+                char *ptr;
+                char *map;
+                u32 size;
+                size = btrfs_file_extent_inline_len(leaf->items +
+                                                    path->slots[0]);
+                extent_end = (extent_start + size) >> inode->i_blkbits;
+                extent_start >>= inode->i_blkbits;
+                if (iblock < extent_start || iblock > extent_end) {
+                        goto out;
+                }
+                ptr = btrfs_file_extent_inline_start(item);
+                map = kmap(result->b_page);
+                memcpy(map, ptr, size);
+                memset(map + size, 0, PAGE_CACHE_SIZE - size);
+                flush_dcache_page(result->b_page);
+                kunmap(result->b_page);
+                set_buffer_uptodate(result);
+                SetPageChecked(result->b_page);
+                btrfs_map_bh_to_logical(root, result, 0);
         }
-        inode->i_blocks += inode->i_sb->s_blocksize >> 9;
-        set_buffer_new(result);
-        map_bh(result, inode->i_sb, blocknr);
-
-        btrfs_map_bh_to_logical(root, result, blocknr);
-#endif
 out:
         btrfs_release_path(root, path);
         btrfs_free_path(path);
-        if (trans)
-                btrfs_end_transaction(trans, root);
         return err;
 }
 
@@ -1124,7 +1104,6 @@ static int btrfs_get_block(struct inode *inode, sector_t iblock,
         struct btrfs_root *root = BTRFS_I(inode)->root;
         mutex_lock(&root->fs_info->fs_mutex);
         err = btrfs_get_block_lock(inode, iblock, result, create);
-        // err = btrfs_get_block_inline(inode, iblock, result, create);
         mutex_unlock(&root->fs_info->fs_mutex);
         return err;
 }
@@ -1134,11 +1113,6 @@ static int btrfs_prepare_write(struct file *file, struct page *page,
 {
         return nobh_prepare_write(page, from, to, btrfs_get_block);
 }
-static int btrfs_commit_write(struct file *file, struct page *page,
-                               unsigned from, unsigned to)
-{
-        return nobh_commit_write(file, page, from, to);
-}
 
 static void btrfs_write_super(struct super_block *sb)
 {
@@ -1150,9 +1124,227 @@ static int btrfs_readpage(struct file *file, struct page *page)
         return mpage_readpage(page, btrfs_get_block);
 }
 
+/*
+ * While block_write_full_page is writing back the dirty buffers under
+ * the page lock, whoever dirtied the buffers may decide to clean them
+ * again at any time.  We handle that by only looking at the buffer
+ * state inside lock_buffer().
+ *
+ * If block_write_full_page() is called for regular writeback
+ * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a
+ * locked buffer.   This only can happen if someone has written the buffer
+ * directly, with submit_bh().  At the address_space level PageWriteback
+ * prevents this contention from occurring.
+ */
+static int __btrfs_write_full_page(struct inode *inode, struct page *page,
+                                   struct writeback_control *wbc)
+{
+        int err;
+        sector_t block;
+        sector_t last_block;
+        struct buffer_head *bh, *head;
+        const unsigned blocksize = 1 << inode->i_blkbits;
+        int nr_underway = 0;
+
+        BUG_ON(!PageLocked(page));
+
+        last_block = (i_size_read(inode) - 1) >> inode->i_blkbits;
+
+        if (!page_has_buffers(page)) {
+                create_empty_buffers(page, blocksize,
+                                        (1 << BH_Dirty)|(1 << BH_Uptodate));
+        }
+
+        /*
+         * Be very careful.  We have no exclusion from __set_page_dirty_buffers
+         * here, and the (potentially unmapped) buffers may become dirty at
+         * any time.  If a buffer becomes dirty here after we've inspected it
+         * then we just miss that fact, and the page stays dirty.
+         *
+         * Buffers outside i_size may be dirtied by __set_page_dirty_buffers;
+         * handle that here by just cleaning them.
+         */
+
+        block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
+        head = page_buffers(page);
+        bh = head;
+
+        /*
+         * Get all the dirty buffers mapped to disk addresses and
+         * handle any aliases from the underlying blockdev's mapping.
+         */
+        do {
+                if (block > last_block) {
+                        /*
+                         * mapped buffers outside i_size will occur, because
+                         * this page can be outside i_size when there is a
+                         * truncate in progress.
+                         */
+                        /*
+                         * The buffer was zeroed by block_write_full_page()
+                         */
+                        clear_buffer_dirty(bh);
+                        set_buffer_uptodate(bh);
+                } else if (!buffer_mapped(bh) && buffer_dirty(bh)) {
+                        WARN_ON(bh->b_size != blocksize);
+                        err = btrfs_get_block(inode, block, bh, 0);
+                        if (err)
+                                goto recover;
+                        if (buffer_new(bh)) {
+                                /* blockdev mappings never come here */
+                                clear_buffer_new(bh);
+                                unmap_underlying_metadata(bh->b_bdev,
+                                                        bh->b_blocknr);
+                        }
+                }
+                bh = bh->b_this_page;
+                block++;
+        } while (bh != head);
+
+        do {
+                if (!buffer_mapped(bh))
+                        continue;
+                /*
+                 * If it's a fully non-blocking write attempt and we cannot
+                 * lock the buffer then redirty the page.  Note that this can
+                 * potentially cause a busy-wait loop from pdflush and kswapd
+                 * activity, but those code paths have their own higher-level
+                 * throttling.
+                 */
+                if (wbc->sync_mode != WB_SYNC_NONE || !wbc->nonblocking) {
+                        lock_buffer(bh);
+                } else if (test_set_buffer_locked(bh)) {
+                        redirty_page_for_writepage(wbc, page);
+                        continue;
+                }
+                if (test_clear_buffer_dirty(bh) && bh->b_blocknr != 0) {
+                        mark_buffer_async_write(bh);
+                } else {
+                        unlock_buffer(bh);
+                }
+        } while ((bh = bh->b_this_page) != head);
+
+        /*
+         * The page and its buffers are protected by PageWriteback(), so we can
+         * drop the bh refcounts early.
+         */
+        BUG_ON(PageWriteback(page));
+        set_page_writeback(page);
+
+        do {
+                struct buffer_head *next = bh->b_this_page;
+                if (buffer_async_write(bh)) {
+                        submit_bh(WRITE, bh);
+                        nr_underway++;
+                }
+                bh = next;
+        } while (bh != head);
+        unlock_page(page);
+
+        err = 0;
+done:
+        if (nr_underway == 0) {
+                /*
+                 * The page was marked dirty, but the buffers were
+                 * clean.  Someone wrote them back by hand with
+                 * ll_rw_block/submit_bh.  A rare case.
+                 */
+                int uptodate = 1;
+                do {
+                        if (!buffer_uptodate(bh)) {
+                                uptodate = 0;
+                                break;
+                        }
+                        bh = bh->b_this_page;
+                } while (bh != head);
+                if (uptodate)
+                        SetPageUptodate(page);
+                end_page_writeback(page);
+                /*
+                 * The page and buffer_heads can be released at any time from
+                 * here on.
+                 */
+                wbc->pages_skipped++;   /* We didn't write this page */
+        }
+        return err;
+
+recover:
+        /*
+         * ENOSPC, or some other error.  We may already have added some
+         * blocks to the file, so we need to write these out to avoid
+         * exposing stale data.
+         * The page is currently locked and not marked for writeback
+         */
+        bh = head;
+        /* Recovery: lock and submit the mapped buffers */
+        do {
+                if (buffer_mapped(bh) && buffer_dirty(bh)) {
+                        lock_buffer(bh);
+                        mark_buffer_async_write(bh);
+                } else {
+                        /*
+                         * The buffer may have been set dirty during
+                         * attachment to a dirty page.
+                         */
+                        clear_buffer_dirty(bh);
+                }
+        } while ((bh = bh->b_this_page) != head);
+        SetPageError(page);
+        BUG_ON(PageWriteback(page));
+        set_page_writeback(page);
+        do {
+                struct buffer_head *next = bh->b_this_page;
+                if (buffer_async_write(bh)) {
+                        clear_buffer_dirty(bh);
+                        submit_bh(WRITE, bh);
+                        nr_underway++;
+                }
+                bh = next;
+        } while (bh != head);
+        unlock_page(page);
+        goto done;
+}
+
+/*
+ * The generic ->writepage function for buffer-backed address_spaces
+ */
 static int btrfs_writepage(struct page *page, struct writeback_control *wbc)
 {
-        return nobh_writepage(page, btrfs_get_block, wbc);
+        struct inode * const inode = page->mapping->host;
+        loff_t i_size = i_size_read(inode);
+        const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
+        unsigned offset;
+        void *kaddr;
+
+        /* Is the page fully inside i_size? */
+        if (page->index < end_index)
+                return __btrfs_write_full_page(inode, page, wbc);
+
+        /* Is the page fully outside i_size? (truncate in progress) */
+        offset = i_size & (PAGE_CACHE_SIZE-1);
+        if (page->index >= end_index+1 || !offset) {
+                /*
+                 * The page may have dirty, unmapped buffers.  For example,
+                 * they may have been added in ext3_writepage().  Make them
+                 * freeable here, so the page does not leak.
+                 */
+                block_invalidatepage(page, 0);
+                unlock_page(page);
+                return 0; /* don't care */
+        }
+
+        /*
+         * The page straddles i_size.  It must be zeroed out on each and every
+         * writepage invokation because it may be mmapped.  "A file is mapped
+         * in multiples of the page size.  For a file that is not a multiple of
+         * the  page size, the remaining memory is zeroed when mapped, and
+         * writes to that region are not written out to the file."
+         */
+        kaddr = kmap_atomic(page, KM_USER0);
+        memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset);
+        flush_dcache_page(page);
+        kunmap_atomic(kaddr, KM_USER0);
+        return __btrfs_write_full_page(inode, page, wbc);
 }
 
 static void btrfs_truncate(struct inode *inode)
@@ -1179,6 +1371,29 @@ static void btrfs_truncate(struct inode *inode)
         mark_inode_dirty(inode);
 }
 
+/*
+ * Make sure any changes to nobh_commit_write() are reflected in
+ * nobh_truncate_page(), since it doesn't call commit_write().
+ */
+static int btrfs_commit_write(struct file *file, struct page *page,
+                              unsigned from, unsigned to)
+{
+        struct inode *inode = page->mapping->host;
+        struct buffer_head *bh;
+        loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
+
+        SetPageUptodate(page);
+        bh = page_buffers(page);
+        if (buffer_mapped(bh) && bh->b_blocknr != 0) {
+                set_page_dirty(page);
+        }
+        if (pos > inode->i_size) {
+                i_size_write(inode, pos);
+                mark_inode_dirty(inode);
+        }
+        return 0;
+}
+
 static int btrfs_copy_from_user(loff_t pos, int num_pages, int write_bytes,
                                 struct page **prepared_pages,
                                 const char __user * buf)
@@ -1234,6 +1449,8 @@ static int dirty_and_release_pages(struct btrfs_trans_handle *trans,
         int ret;
         int this_write;
         struct inode *inode = file->f_path.dentry->d_inode;
+        struct buffer_head *bh;
+        struct btrfs_file_extent_item *ei;
 
         for (i = 0; i < num_pages; i++) {
                 offset = pos & (PAGE_CACHE_SIZE -1);
@@ -1242,16 +1459,47 @@ static int dirty_and_release_pages(struct btrfs_trans_handle *trans,
 
                 mutex_lock(&root->fs_info->fs_mutex);
                 trans = btrfs_start_transaction(root, 1);
-                btrfs_csum_file_block(trans, root, inode->i_ino,
+
+                bh = page_buffers(pages[i]);
+                if (buffer_mapped(bh) && bh->b_blocknr == 0) {
+                        struct btrfs_key key;
+                        struct btrfs_path *path;
+                        char *ptr;
+                        u32 datasize;
+
+                        path = btrfs_alloc_path();
+                        BUG_ON(!path);
+                        key.objectid = inode->i_ino;
+                        key.offset = pages[i]->index << PAGE_CACHE_SHIFT;
+                        key.flags = 0;
+                        btrfs_set_key_type(&key, BTRFS_EXTENT_DATA_KEY);
+                        BUG_ON(write_bytes >= PAGE_CACHE_SIZE);
+                        datasize = offset +
+                                btrfs_file_extent_calc_inline_size(write_bytes);
+                        ret = btrfs_insert_empty_item(trans, root, path, &key,
+                                                      datasize);
+                        BUG_ON(ret);
+                        ei = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]),
+                               path->slots[0], struct btrfs_file_extent_item);
+                        btrfs_set_file_extent_generation(ei, trans->transid);
+                        btrfs_set_file_extent_type(ei,
+                                                   BTRFS_FILE_EXTENT_INLINE);
+                        ptr = btrfs_file_extent_inline_start(ei);
+                        memcpy(ptr, bh->b_data, offset + write_bytes);
+                        mark_buffer_dirty(path->nodes[0]);
+                        btrfs_free_path(path);
+                } else {
+                        btrfs_csum_file_block(trans, root, inode->i_ino,
                                       pages[i]->index << PAGE_CACHE_SHIFT,
                                       kmap(pages[i]), PAGE_CACHE_SIZE);
-                kunmap(pages[i]);
+                        kunmap(pages[i]);
+                }
                 SetPageChecked(pages[i]);
                 ret = btrfs_end_transaction(trans, root);
                 BUG_ON(ret);
                 mutex_unlock(&root->fs_info->fs_mutex);
 
-                ret = nobh_commit_write(file, pages[i], offset,
+                ret = btrfs_commit_write(file, pages[i], offset,
                                          offset + this_write);
                 pos += this_write;
                 if (ret) {
@@ -1275,12 +1523,16 @@ static int drop_extents(struct btrfs_trans_handle *trans,
         struct btrfs_leaf *leaf;
         int slot;
         struct btrfs_file_extent_item *extent;
-        u64 extent_end;
+        u64 extent_end = 0;
         int keep;
         struct btrfs_file_extent_item old;
         struct btrfs_path *path;
         u64 search_start = start;
         int bookend;
+        int found_type;
+        int found_extent;
+        int found_inline;
+
         path = btrfs_alloc_path();
         if (!path)
                 return -ENOMEM;
@@ -1292,37 +1544,62 @@ static int drop_extents(struct btrfs_trans_handle *trans,
                         goto out;
                 if (ret > 0) {
                         if (path->slots[0] == 0) {
-                                ret = -ENOENT;
+                                ret = 0;
                                 goto out;
                         }
                         path->slots[0]--;
                 }
                 keep = 0;
                 bookend = 0;
+                found_extent = 0;
+                found_inline = 0;
+                extent = NULL;
                 leaf = btrfs_buffer_leaf(path->nodes[0]);
                 slot = path->slots[0];
                 btrfs_disk_key_to_cpu(&key, &leaf->items[slot].key);
-                extent = btrfs_item_ptr(leaf, slot,
-                                        struct btrfs_file_extent_item);
-                extent_end = key.offset +
-                        (btrfs_file_extent_num_blocks(extent) <<
-                         inode->i_blkbits);
                 if (key.offset >= end || key.objectid != inode->i_ino) {
                         ret = 0;
                         goto out;
                 }
-                if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY)
+                if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY) {
+                        ret = 0;
+                        goto out;
+                }
+                extent = btrfs_item_ptr(leaf, slot,
+                                        struct btrfs_file_extent_item);
+                found_type = btrfs_file_extent_type(extent);
+                if (found_type == BTRFS_FILE_EXTENT_REG) {
+                        extent_end = key.offset +
+                                (btrfs_file_extent_num_blocks(extent) <<
+                                 inode->i_blkbits);
+                        found_extent = 1;
+                } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
+                        found_inline = 1;
+                        extent_end = key.offset +
+                             btrfs_file_extent_inline_len(leaf->items + slot);
+                }
+
+                if (!found_extent && !found_inline) {
+                        ret = 0;
                         goto out;
-                if (search_start >= extent_end)
+                }
+
+                if (search_start >= extent_end) {
+                        ret = 0;
                         goto out;
+                }
+
                 search_start = extent_end;
 
                 if (end < extent_end && end >= key.offset) {
-                        memcpy(&old, extent, sizeof(old));
-                        ret = btrfs_inc_extent_ref(trans, root,
-                                   btrfs_file_extent_disk_blocknr(&old),
-                                   btrfs_file_extent_disk_num_blocks(&old));
-                        BUG_ON(ret);
+                        if (found_extent) {
+                                memcpy(&old, extent, sizeof(old));
+                                ret = btrfs_inc_extent_ref(trans, root,
+                                      btrfs_file_extent_disk_blocknr(&old),
+                                      btrfs_file_extent_disk_num_blocks(&old));
+                                BUG_ON(ret);
+                        }
+                        WARN_ON(found_inline);
                         bookend = 1;
                 }
 
@@ -1332,25 +1609,45 @@ static int drop_extents(struct btrfs_trans_handle *trans,
                         /* truncate existing extent */
                         keep = 1;
                         WARN_ON(start & (root->blocksize - 1));
-                        new_num = (start - key.offset) >> inode->i_blkbits;
-                        old_num = btrfs_file_extent_num_blocks(extent);
-                        inode->i_blocks -= (old_num - new_num) << 3;
-                        btrfs_set_file_extent_num_blocks(extent, new_num);
-                        mark_buffer_dirty(path->nodes[0]);
+                        if (found_extent) {
+                                new_num = (start - key.offset) >>
+                                        inode->i_blkbits;
+                                old_num = btrfs_file_extent_num_blocks(extent);
+                                inode->i_blocks -= (old_num - new_num) << 3;
+                                btrfs_set_file_extent_num_blocks(extent,
+                                                                 new_num);
+                                mark_buffer_dirty(path->nodes[0]);
+                        } else {
+                                WARN_ON(1);
+                                /*
+                                ret = btrfs_truncate_item(trans, root, path,
+                                                          start - key.offset);
+                                BUG_ON(ret);
+                                */
+                        }
                 }
                 if (!keep) {
-                        u64 disk_blocknr;
-                        u64 disk_num_blocks;
-                        disk_blocknr = btrfs_file_extent_disk_blocknr(extent);
-                        disk_num_blocks =
-                                btrfs_file_extent_disk_num_blocks(extent);
+                        u64 disk_blocknr = 0;
+                        u64 disk_num_blocks = 0;
+                        u64 extent_num_blocks = 0;
+                        if (found_extent) {
+                                disk_blocknr =
+                                      btrfs_file_extent_disk_blocknr(extent);
+                                disk_num_blocks =
+                                      btrfs_file_extent_disk_num_blocks(extent);
+                                extent_num_blocks =
+                                      btrfs_file_extent_num_blocks(extent);
+                        }
                         ret = btrfs_del_item(trans, root, path);
                         BUG_ON(ret);
-                        inode->i_blocks -=
-                                btrfs_file_extent_num_blocks(extent) << 3;
                         btrfs_release_path(root, path);
-                        ret = btrfs_free_extent(trans, root, disk_blocknr,
-                                                disk_num_blocks, 0);
+                        if (found_extent) {
+                                inode->i_blocks -=
+                                btrfs_file_extent_num_blocks(extent) << 3;
+                                ret = btrfs_free_extent(trans, root,
+                                                        disk_blocknr,
+                                                        disk_num_blocks, 0);
+                        }
 
                         BUG_ON(ret);
                         if (!bookend && search_start >= end) {
@@ -1360,7 +1657,7 @@ static int drop_extents(struct btrfs_trans_handle *trans,
                         if (!bookend)
                                 continue;
                 }
-                if (bookend) {
+                if (bookend && found_extent) {
                         /* create bookend */
                         struct btrfs_key ins;
                         ins.objectid = inode->i_ino;
@@ -1390,6 +1687,8 @@ static int drop_extents(struct btrfs_trans_handle *trans,
                                     btrfs_file_extent_num_blocks(&old) -
                                     ((end - key.offset) >> inode->i_blkbits));
 
+                        btrfs_set_file_extent_type(extent,
+                                                   BTRFS_FILE_EXTENT_REG);
                         btrfs_set_file_extent_generation(extent,
                                     btrfs_file_extent_generation(&old));
                         btrfs_mark_buffer_dirty(path->nodes[0]);
@@ -1445,7 +1744,8 @@ static int prepare_pages(struct btrfs_root *root,
                         if (err)
                                 goto failed_truncate;
                         bh = bh->b_this_page;
-                        alloc_extent_start++;
+                        if (alloc_extent_start)
+                                alloc_extent_start++;
                 } while (bh != head);
                 pos += this_write;
                 WARN_ON(this_write > write_bytes);
@@ -1543,12 +1843,20 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
                                    start_pos,
                                    (pos + count + root->blocksize -1) &
                                    ~((u64)root->blocksize - 1));
+                BUG_ON(ret);
         }
-        ret = btrfs_alloc_extent(trans, root, num_blocks, 1,
+        if (inode->i_size >= PAGE_CACHE_SIZE || pos + count < inode->i_size ||
+            pos + count - start_pos > BTRFS_MAX_INLINE_DATA_SIZE(root)) {
+                ret = btrfs_alloc_extent(trans, root, num_blocks, 1,
                                  (u64)-1, &ins);
-        BUG_ON(ret);
-        ret = btrfs_insert_file_extent(trans, root, inode->i_ino,
+                BUG_ON(ret);
+                ret = btrfs_insert_file_extent(trans, root, inode->i_ino,
                                        start_pos, ins.objectid, ins.offset);
+                BUG_ON(ret);
+        } else {
+                ins.offset = 0;
+                ins.objectid = 0;
+        }
         BUG_ON(ret);
         alloc_extent_start = ins.objectid;
         ret = btrfs_end_transaction(trans, root);
@@ -1567,7 +1875,8 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
                 BUG_ON(ret);
 
                 /* FIXME blocks != pagesize */
-                alloc_extent_start += num_pages;
+                if (alloc_extent_start)
+                        alloc_extent_start += num_pages;
                 ret = btrfs_copy_from_user(pos, num_pages,
                                            write_bytes, pages, buf);
                 BUG_ON(ret);
@@ -1779,10 +2088,11 @@ static int btrfs_read_actor(read_descriptor_t *desc, struct page *page,
         if (!PageChecked(page)) {
                 /* FIXME, do it per block */
                 struct btrfs_root *root = BTRFS_I(inode)->root;
+
                 int ret = btrfs_csum_verify_file_block(root,
-                                          page->mapping->host->i_ino,
-                                          page->index << PAGE_CACHE_SHIFT,
-                                          kmap(page), PAGE_CACHE_SIZE);
+                                  page->mapping->host->i_ino,
+                                  page->index << PAGE_CACHE_SHIFT,
+                                  kmap(page), PAGE_CACHE_SIZE);
                 if (ret) {
                         printk("failed to verify ino %lu page %lu\n",
                                page->mapping->host->i_ino,
@@ -2249,6 +2559,16 @@ static int btrfs_get_sb(struct file_system_type *fs_type,
                            btrfs_fill_super, mnt);
 }
 
+
+static int btrfs_getattr(struct vfsmount *mnt,
+                         struct dentry *dentry, struct kstat *stat)
+{
+        struct inode *inode = dentry->d_inode;
+        generic_fillattr(inode, stat);
+        stat->blksize = 256 * 1024;
+        return 0;
+}
+
 static struct file_system_type btrfs_fs_type = {
         .owner          = THIS_MODULE,
         .name           = "btrfs",
@@ -2298,6 +2618,7 @@ static struct address_space_operations btrfs_aops = {
 
 static struct inode_operations btrfs_file_inode_operations = {
         .truncate       = btrfs_truncate,
+        .getattr        = btrfs_getattr,
 };
 
 static struct file_operations btrfs_file_operations = {