4 files changed, 335 insertions, 41 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 19c0dd33b1e..c0c95cccbb5 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1512,7 +1512,8 @@ cow_done:
                         if (ret && slot > 0)
                                 slot -= 1;
                         p->slots[level] = slot;
-                        if (ins_len > 0 && btrfs_header_nritems(b) >=
+                        if ((p->search_for_split || ins_len > 0) &&
+                            btrfs_header_nritems(b) >=
                             BTRFS_NODEPTRS_PER_BLOCK(root) - 3) {
                                 int sret = split_node(trans, root, p, level);
                                 BUG_ON(sret > 0);
@@ -1596,7 +1597,8 @@ cow_done:
                                         goto done;
                                 }
                         }
-                        unlock_up(p, level, lowest_unlock);
+                        if (!p->search_for_split)
+                                unlock_up(p, level, lowest_unlock);
                         goto done;
                 }
         }
@@ -2636,11 +2638,11 @@ static noinline int split_leaf(struct btrfs_trans_handle *trans,
         int num_doubles = 0;
         struct btrfs_disk_key disk_key;
 
-        if (extend)
+        if (extend && data_size)
                 space_needed = data_size;
 
         /* first try to make some room by pushing left and right */
-        if (ins_key->type != BTRFS_DIR_ITEM_KEY) {
+        if (data_size && ins_key->type != BTRFS_DIR_ITEM_KEY) {
                 wret = push_leaf_right(trans, root, path, data_size, 0);
                 if (wret < 0) {
                         return wret;
@@ -2721,7 +2723,7 @@ again:
         } else {
                 if (leaf_space_used(l, 0, mid + 1) + space_needed >
                         BTRFS_LEAF_DATA_SIZE(root)) {
-                        if (!extend && slot == 0) {
+                        if (!extend && data_size && slot == 0) {
                                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
                                 btrfs_set_header_nritems(right, 0);
                                 wret = insert_ptr(trans, root, path,
@@ -2742,7 +2744,7 @@ again:
                                 }
                                 btrfs_mark_buffer_dirty(right);
                                 return ret;
-                        } else if (extend && slot == 0) {
+                        } else if ((extend || !data_size) && slot == 0) {
                                 mid = 1;
                         } else {
                                 mid = slot;
@@ -2828,6 +2830,123 @@ again:
 }
 
 /*
+ * This function splits a single item into two items,
+ * giving 'new_key' to the new item and splitting the
+ * old one at split_offset (from the start of the item).
+ *
+ * The path may be released by this operation.  After
+ * the split, the path is pointing to the old item.  The
+ * new item is going to be in the same node as the old one.
+ *
+ * Note, the item being split must be smaller enough to live alone on
+ * a tree block with room for one extra struct btrfs_item
+ *
+ * This allows us to split the item in place, keeping a lock on the
+ * leaf the entire time.
+ */
+int btrfs_split_item(struct btrfs_trans_handle *trans,
+                     struct btrfs_root *root,
+                     struct btrfs_path *path,
+                     struct btrfs_key *new_key,
+                     unsigned long split_offset)
+{
+        u32 item_size;
+        struct extent_buffer *leaf;
+        struct btrfs_key orig_key;
+        struct btrfs_item *item;
+        struct btrfs_item *new_item;
+        int ret = 0;
+        int slot;
+        u32 nritems;
+        u32 orig_offset;
+        struct btrfs_disk_key disk_key;
+        char *buf;
+
+        leaf = path->nodes[0];
+        btrfs_item_key_to_cpu(leaf, &orig_key, path->slots[0]);
+        if (btrfs_leaf_free_space(root, leaf) >= sizeof(struct btrfs_item))
+                goto split;
+
+        item_size = btrfs_item_size_nr(leaf, path->slots[0]);
+        btrfs_release_path(root, path);
+
+        path->search_for_split = 1;
+        path->keep_locks = 1;
+
+        ret = btrfs_search_slot(trans, root, &orig_key, path, 0, 1);
+        path->search_for_split = 0;
+
+        /* if our item isn't there or got smaller, return now */
+        if (ret != 0 || item_size != btrfs_item_size_nr(path->nodes[0],
+                                                        path->slots[0])) {
+                path->keep_locks = 0;
+                return -EAGAIN;
+        }
+
+        ret = split_leaf(trans, root, &orig_key, path, 0, 0);
+        path->keep_locks = 0;
+        BUG_ON(ret);
+
+        BUG_ON(btrfs_leaf_free_space(root, leaf) < sizeof(struct btrfs_item));
+        leaf = path->nodes[0];
+
+split:
+        item = btrfs_item_nr(leaf, path->slots[0]);
+        orig_offset = btrfs_item_offset(leaf, item);
+        item_size = btrfs_item_size(leaf, item);
+
+
+        buf = kmalloc(item_size, GFP_NOFS);
+        read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
+                            path->slots[0]), item_size);
+        slot = path->slots[0] + 1;
+        leaf = path->nodes[0];
+
+        nritems = btrfs_header_nritems(leaf);
+
+        if (slot != nritems) {
+                /* shift the items */
+                memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
+                              btrfs_item_nr_offset(slot),
+                              (nritems - slot) * sizeof(struct btrfs_item));
+
+        }
+
+        btrfs_cpu_key_to_disk(&disk_key, new_key);
+        btrfs_set_item_key(leaf, &disk_key, slot);
+
+        new_item = btrfs_item_nr(leaf, slot);
+
+        btrfs_set_item_offset(leaf, new_item, orig_offset);
+        btrfs_set_item_size(leaf, new_item, item_size - split_offset);
+
+        btrfs_set_item_offset(leaf, item,
+                              orig_offset + item_size - split_offset);
+        btrfs_set_item_size(leaf, item, split_offset);
+
+        btrfs_set_header_nritems(leaf, nritems + 1);
+
+        /* write the data for the start of the original item */
+        write_extent_buffer(leaf, buf,
+                            btrfs_item_ptr_offset(leaf, path->slots[0]),
+                            split_offset);
+
+        /* write the data for the new item */
+        write_extent_buffer(leaf, buf + split_offset,
+                            btrfs_item_ptr_offset(leaf, slot),
+                            item_size - split_offset);
+        btrfs_mark_buffer_dirty(leaf);
+
+        ret = 0;
+        if (btrfs_leaf_free_space(root, leaf) < 0) {
+                btrfs_print_leaf(root, leaf);
+                BUG();
+        }
+        kfree(buf);
+        return ret;
+}
+
+/*
  * make the item pointed to by the path smaller.  new_size indicates
  * how small to make it, and from_end tells us if we just chop bytes
  * off the end of the item or if we shift the item to chop bytes off
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index f72b4381934..5b0c79d22c0 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -409,6 +409,12 @@ struct btrfs_path {
         int keep_locks;
         int skip_locking;
         int lowest_level;
+
+        /*
+         * set by btrfs_split_item, tells search_slot to keep all locks
+         * and to force calls to keep space in the nodes
+         */
+        int search_for_split;
 };
 
 /*
@@ -1816,6 +1822,11 @@ int btrfs_truncate_item(struct btrfs_trans_handle *trans,
                         struct btrfs_root *root,
                         struct btrfs_path *path,
                         u32 new_size, int from_end);
+int btrfs_split_item(struct btrfs_trans_handle *trans,
+                     struct btrfs_root *root,
+                     struct btrfs_path *path,
+                     struct btrfs_key *new_key,
+                     unsigned long split_offset);
 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
                       *root, struct btrfs_key *key, struct btrfs_path *p, int
                       ins_len, int cow);
@@ -1953,6 +1964,8 @@ int btrfs_lookup_inode(struct btrfs_trans_handle *trans, struct btrfs_root
                        struct btrfs_key *location, int mod);
 
 /* file-item.c */
+int btrfs_del_csums(struct btrfs_trans_handle *trans,
+                    struct btrfs_root *root, u64 bytenr, u64 len);
 int btrfs_lookup_bio_sums(struct btrfs_root *root, struct inode *inode,
                           struct bio *bio, u32 *dst);
 int btrfs_insert_file_extent(struct btrfs_trans_handle *trans,
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 803647bc840..cc74316dc42 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2484,7 +2484,6 @@ static int __free_extent(struct btrfs_trans_handle *trans,
                                 mark_free = 1;
                         BUG_ON(ret < 0);
                 }
-
                 /* block accounting for super block */
                 spin_lock_irq(&info->delalloc_lock);
                 super_used = btrfs_super_bytes_used(&info->super_copy);
@@ -2504,6 +2503,11 @@ static int __free_extent(struct btrfs_trans_handle *trans,
                                          mark_free);
                 BUG_ON(ret);
 
+                if (owner_objectid >= BTRFS_FIRST_FREE_OBJECTID) {
+                        ret = btrfs_del_csums(trans, root, bytenr, num_bytes);
+                        BUG_ON(ret);
+                }
+
 #ifdef BIO_RW_DISCARD
                 /* Tell the block device(s) that the sectors can be discarded */
                 ret = btrfs_map_block(&root->fs_info->mapping_tree, READ,
diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index a3ad2ce0011..3ebef871ee6 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -310,6 +310,179 @@ int btrfs_csum_one_bio(struct btrfs_root *root, struct inode *inode,
         return 0;
 }
 
+/*
+ * helper function for csum removal, this expects the
+ * key to describe the csum pointed to by the path, and it expects
+ * the csum to overlap the range [bytenr, len]
+ *
+ * The csum should not be entirely contained in the range and the
+ * range should not be entirely contained in the csum.
+ *
+ * This calls btrfs_truncate_item with the correct args based on the
+ * overlap, and fixes up the key as required.
+ */
+static noinline int truncate_one_csum(struct btrfs_trans_handle *trans,
+                                      struct btrfs_root *root,
+                                      struct btrfs_path *path,
+                                      struct btrfs_key *key,
+                                      u64 bytenr, u64 len)
+{
+        struct extent_buffer *leaf;
+        u16 csum_size =
+                btrfs_super_csum_size(&root->fs_info->super_copy);
+        u64 csum_end;
+        u64 end_byte = bytenr + len;
+        u32 blocksize_bits = root->fs_info->sb->s_blocksize_bits;
+        int ret;
+
+        leaf = path->nodes[0];
+        csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
+        csum_end <<= root->fs_info->sb->s_blocksize_bits;
+        csum_end += key->offset;
+
+        if (key->offset < bytenr && csum_end <= end_byte) {
+                /*
+                 *         [ bytenr - len ]
+                 *         [   ]
+                 *   [csum     ]
+                 *   A simple truncate off the end of the item
+                 */
+                u32 new_size = (bytenr - key->offset) >> blocksize_bits;
+                new_size *= csum_size;
+                ret = btrfs_truncate_item(trans, root, path, new_size, 1);
+                BUG_ON(ret);
+        } else if (key->offset >= bytenr && csum_end > end_byte &&
+                   end_byte > key->offset) {
+                /*
+                 *         [ bytenr - len ]
+                 *                 [ ]
+                 *                 [csum     ]
+                 * we need to truncate from the beginning of the csum
+                 */
+                u32 new_size = (csum_end - end_byte) >> blocksize_bits;
+                new_size *= csum_size;
+
+                ret = btrfs_truncate_item(trans, root, path, new_size, 0);
+                BUG_ON(ret);
+
+                key->offset = end_byte;
+                ret = btrfs_set_item_key_safe(trans, root, path, key);
+                BUG_ON(ret);
+        } else {
+                BUG();
+        }
+        return 0;
+}
+
+/*
+ * deletes the csum items from the csum tree for a given
+ * range of bytes.
+ */
+int btrfs_del_csums(struct btrfs_trans_handle *trans,
+                    struct btrfs_root *root, u64 bytenr, u64 len)
+{
+        struct btrfs_path *path;
+        struct btrfs_key key;
+        u64 end_byte = bytenr + len;
+        u64 csum_end;
+        struct extent_buffer *leaf;
+        int ret;
+        u16 csum_size =
+                btrfs_super_csum_size(&root->fs_info->super_copy);
+        int blocksize_bits = root->fs_info->sb->s_blocksize_bits;
+
+        root = root->fs_info->csum_root;
+
+        path = btrfs_alloc_path();
+
+        while(1) {
+                key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
+                key.offset = end_byte - 1;
+                key.type = BTRFS_EXTENT_CSUM_KEY;
+
+                ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
+                if (ret > 0) {
+                        if (path->slots[0] == 0)
+                                goto out;
+                        path->slots[0]--;
+                }
+                leaf = path->nodes[0];
+                btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+
+                if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
+                    key.type != BTRFS_EXTENT_CSUM_KEY) {
+                        break;
+                }
+
+                if (key.offset >= end_byte)
+                        break;
+
+                csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
+                csum_end <<= blocksize_bits;
+                csum_end += key.offset;
+
+                /* this csum ends before we start, we're done */
+                if (csum_end <= bytenr)
+                        break;
+
+                /* delete the entire item, it is inside our range */
+                if (key.offset >= bytenr && csum_end <= end_byte) {
+                        ret = btrfs_del_item(trans, root, path);
+                        BUG_ON(ret);
+                } else if (key.offset < bytenr && csum_end > end_byte) {
+                        unsigned long offset;
+                        unsigned long shift_len;
+                        unsigned long item_offset;
+                        /*
+                         *        [ bytenr - len ]
+                         *     [csum                ]
+                         *
+                         * Our bytes are in the middle of the csum,
+                         * we need to split this item and insert a new one.
+                         *
+                         * But we can't drop the path because the
+                         * csum could change, get removed, extended etc.
+                         *
+                         * The trick here is the max size of a csum item leaves
+                         * enough room in the tree block for a single
+                         * item header.  So, we split the item in place,
+                         * adding a new header pointing to the existing
+                         * bytes.  Then we loop around again and we have
+                         * a nicely formed csum item that we can neatly
+                         * truncate.
+                         */
+                        offset = (bytenr - key.offset) >> blocksize_bits;
+                        offset *= csum_size;
+
+                        shift_len = (len >> blocksize_bits) * csum_size;
+
+                        item_offset = btrfs_item_ptr_offset(leaf,
+                                                            path->slots[0]);
+
+                        memset_extent_buffer(leaf, 0, item_offset + offset,
+                                             shift_len);
+                        key.offset = bytenr;
+
+                        /*
+                         * btrfs_split_item returns -EAGAIN when the
+                         * item changed size or key
+                         */
+                        ret = btrfs_split_item(trans, root, path, &key, offset);
+                        BUG_ON(ret && ret != -EAGAIN);
+
+                        key.offset = end_byte - 1;
+                } else {
+                        ret = truncate_one_csum(trans, root, path,
+                                                &key, bytenr, len);
+                        BUG_ON(ret);
+                }
+                btrfs_release_path(root, path);
+        }
+out:
+        btrfs_free_path(path);
+        return 0;
+}
+
 int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
                            struct btrfs_root *root,
                            struct btrfs_ordered_sum *sums)
@@ -396,28 +569,40 @@ again:
                                 csum_size, 1);
         if (ret < 0)
                 goto fail_unlock;
-        if (ret == 0) {
-                BUG();
-        }
-        if (path->slots[0] == 0) {
-                goto insert;
+
+        if (ret > 0) {
+                if (path->slots[0] == 0)
+                        goto insert;
+                path->slots[0]--;
         }
-        path->slots[0]--;
+
         leaf = path->nodes[0];
         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
         csum_offset = (bytenr - found_key.offset) >>
                         root->fs_info->sb->s_blocksize_bits;
+
         if (btrfs_key_type(&found_key) != BTRFS_EXTENT_CSUM_KEY ||
             found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
             csum_offset >= MAX_CSUM_ITEMS(root, csum_size)) {
                 goto insert;
         }
+
         if (csum_offset >= btrfs_item_size_nr(leaf, path->slots[0]) /
             csum_size) {
                 u32 diff = (csum_offset + 1) * csum_size;
+
+                /*
+                 * is the item big enough already?  we dropped our lock
+                 * before and need to recheck
+                 */
+                if (diff < btrfs_item_size_nr(leaf, path->slots[0]))
+                        goto csum;
+
                 diff = diff - btrfs_item_size_nr(leaf, path->slots[0]);
-                if (diff != csum_size)
+                if (diff != csum_size) {
                         goto insert;
+                }
+
                 ret = btrfs_extend_item(trans, root, path, diff);
                 BUG_ON(ret);
                 goto csum;
@@ -518,30 +703,3 @@ out:
 fail_unlock:
         goto out;
 }
-
-int btrfs_csum_truncate(struct btrfs_trans_handle *trans,
-                        struct btrfs_root *root, struct btrfs_path *path,
-                        u64 isize)
-{
-        struct btrfs_key key;
-        struct extent_buffer *leaf = path->nodes[0];
-        int slot = path->slots[0];
-        int ret;
-        u32 new_item_size;
-        u64 new_item_span;
-        u64 blocks;
-
-        btrfs_item_key_to_cpu(leaf, &key, slot);
-        if (isize <= key.offset)
-                return 0;
-        new_item_span = isize - key.offset;
-        blocks = (new_item_span + root->sectorsize - 1) >>
-                root->fs_info->sb->s_blocksize_bits;
-        new_item_size = blocks *
-                btrfs_super_csum_size(&root->fs_info->super_copy);
-        if (new_item_size >= btrfs_item_size_nr(leaf, slot))
-                return 0;
-        ret = btrfs_truncate_item(trans, root, path, new_item_size, 1);
-        BUG_ON(ret);
-        return ret;
-}