1 files changed, 52 insertions, 93 deletions

diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 81296c57405a..6c4e2baa9290 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -1543,29 +1543,26 @@ again:
         end = bitmap_info->offset + (u64)(BITS_PER_BITMAP * ctl->unit) - 1;
 
         /*
-         * XXX - this can go away after a few releases.
-         *
-         * since the only user of btrfs_remove_free_space is the tree logging
-         * stuff, and the only way to test that is under crash conditions, we
-         * want to have this debug stuff here just in case somethings not
-         * working.  Search the bitmap for the space we are trying to use to
-         * make sure its actually there.  If its not there then we need to stop
-         * because something has gone wrong.
+         * We need to search for bits in this bitmap.  We could only cover some
+         * of the extent in this bitmap thanks to how we add space, so we need
+         * to search for as much as it as we can and clear that amount, and then
+         * go searching for the next bit.
          */
         search_start = *offset;
-        search_bytes = *bytes;
+        search_bytes = ctl->unit;
         search_bytes = min(search_bytes, end - search_start + 1);
         ret = search_bitmap(ctl, bitmap_info, &search_start, &search_bytes);
         BUG_ON(ret < 0 || search_start != *offset);
 
-        if (*offset > bitmap_info->offset && *offset + *bytes > end) {
-                bitmap_clear_bits(ctl, bitmap_info, *offset, end - *offset + 1);
-                *bytes -= end - *offset + 1;
-                *offset = end + 1;
-        } else if (*offset >= bitmap_info->offset && *offset + *bytes <= end) {
-                bitmap_clear_bits(ctl, bitmap_info, *offset, *bytes);
-                *bytes = 0;
-        }
+        /* We may have found more bits than what we need */
+        search_bytes = min(search_bytes, *bytes);
+
+        /* Cannot clear past the end of the bitmap */
+        search_bytes = min(search_bytes, end - search_start + 1);
+
+        bitmap_clear_bits(ctl, bitmap_info, search_start, search_bytes);
+        *offset += search_bytes;
+        *bytes -= search_bytes;
 
         if (*bytes) {
                 struct rb_node *next = rb_next(&bitmap_info->offset_index);
@@ -1596,7 +1593,7 @@ again:
                  * everything over again.
                  */
                 search_start = *offset;
-                search_bytes = *bytes;
+                search_bytes = ctl->unit;
                 ret = search_bitmap(ctl, bitmap_info, &search_start,
                                     &search_bytes);
                 if (ret < 0 || search_start != *offset)
@@ -1879,12 +1876,14 @@ int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
 {
         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
         struct btrfs_free_space *info;
-        struct btrfs_free_space *next_info = NULL;
         int ret = 0;
 
         spin_lock(&ctl->tree_lock);
 
 again:
+        if (!bytes)
+                goto out_lock;
+
         info = tree_search_offset(ctl, offset, 0, 0);
         if (!info) {
                 /*
@@ -1905,88 +1904,48 @@ again:
                 }
         }
 
-        if (info->bytes < bytes && rb_next(&info->offset_index)) {
-                u64 end;
-                next_info = rb_entry(rb_next(&info->offset_index),
-                                             struct btrfs_free_space,
-                                             offset_index);
-
-                if (next_info->bitmap)
-                        end = next_info->offset +
-                              BITS_PER_BITMAP * ctl->unit - 1;
-                else
-                        end = next_info->offset + next_info->bytes;
-
-                if (next_info->bytes < bytes ||
-                    next_info->offset > offset || offset > end) {
-                        printk(KERN_CRIT "Found free space at %llu, size %llu,"
-                              " trying to use %llu\n",
-                              (unsigned long long)info->offset,
-                              (unsigned long long)info->bytes,
-                              (unsigned long long)bytes);
-                        WARN_ON(1);
-                        ret = -EINVAL;
-                        goto out_lock;
-                }
-
-                info = next_info;
-        }
-
-        if (info->bytes == bytes) {
+        if (!info->bitmap) {
                 unlink_free_space(ctl, info);
-                if (info->bitmap) {
-                        kfree(info->bitmap);
-                        ctl->total_bitmaps--;
-                }
-                kmem_cache_free(btrfs_free_space_cachep, info);
-                ret = 0;
-                goto out_lock;
-        }
-
-        if (!info->bitmap && info->offset == offset) {
-                unlink_free_space(ctl, info);
-                info->offset += bytes;
-                info->bytes -= bytes;
-                ret = link_free_space(ctl, info);
-                WARN_ON(ret);
-                goto out_lock;
-        }
+                if (offset == info->offset) {
+                        u64 to_free = min(bytes, info->bytes);
+
+                        info->bytes -= to_free;
+                        info->offset += to_free;
+                        if (info->bytes) {
+                                ret = link_free_space(ctl, info);
+                                WARN_ON(ret);
+                        } else {
+                                kmem_cache_free(btrfs_free_space_cachep, info);
+                        }
 
-        if (!info->bitmap && info->offset <= offset &&
-            info->offset + info->bytes >= offset + bytes) {
-                u64 old_start = info->offset;
-                /*
-                 * we're freeing space in the middle of the info,
-                 * this can happen during tree log replay
-                 *
-                 * first unlink the old info and then
-                 * insert it again after the hole we're creating
-                 */
-                unlink_free_space(ctl, info);
-                if (offset + bytes < info->offset + info->bytes) {
-                        u64 old_end = info->offset + info->bytes;
+                        offset += to_free;
+                        bytes -= to_free;
+                        goto again;
+                } else {
+                        u64 old_end = info->bytes + info->offset;
 
-                        info->offset = offset + bytes;
-                        info->bytes = old_end - info->offset;
+                        info->bytes = offset - info->offset;
                         ret = link_free_space(ctl, info);
                         WARN_ON(ret);
                         if (ret)
                                 goto out_lock;
-                } else {
-                        /* the hole we're creating ends at the end
-                         * of the info struct, just free the info
-                         */
-                        kmem_cache_free(btrfs_free_space_cachep, info);
-                }
-                spin_unlock(&ctl->tree_lock);
 
-                /* step two, insert a new info struct to cover
-                 * anything before the hole
-                 */
-                ret = btrfs_add_free_space(block_group, old_start,
-                                           offset - old_start);
-                WARN_ON(ret); /* -ENOMEM */
-                goto out;
+                        /* Not enough bytes in this entry to satisfy us */
+                        if (old_end < offset + bytes) {
+                                bytes -= old_end - offset;
+                                offset = old_end;
+                                goto again;
+                        } else if (old_end == offset + bytes) {
+                                /* all done */
+                                goto out_lock;
+                        }
+                        spin_unlock(&ctl->tree_lock);
+
+                        ret = btrfs_add_free_space(block_group, offset + bytes,
+                                                   old_end - (offset + bytes));
+                        WARN_ON(ret);
+                        goto out;
+                }
         }
 
         ret = remove_from_bitmap(ctl, info, &offset, &bytes);