btrfs: Document __etree_search
[sfrench/cifs-2.6.git] / fs / btrfs / extent_io.c
index db337e53aab338aa2c95170ae3e94731616dcd72..43761ecd12017b0f072ae562385b8d88c1609262 100644 (file)
@@ -359,6 +359,24 @@ do_insert:
        return NULL;
 }
 
+/**
+ * __etree_search - searche @tree for an entry that contains @offset. Such
+ * entry would have entry->start <= offset && entry->end >= offset.
+ *
+ * @tree - the tree to search
+ * @offset - offset that should fall within an entry in @tree
+ * @next_ret - pointer to the first entry whose range ends after @offset
+ * @prev - pointer to the first entry whose range begins before @offset
+ * @p_ret - pointer where new node should be anchored (used when inserting an
+ *         entry in the tree)
+ * @parent_ret - points to entry which would have been the parent of the entry,
+ *               containing @offset
+ *
+ * This function returns a pointer to the entry that contains @offset byte
+ * address. If no such entry exists, then NULL is returned and the other
+ * pointer arguments to the function are filled, otherwise the found entry is
+ * returned and other pointers are left untouched.
+ */
 static struct rb_node *__etree_search(struct extent_io_tree *tree, u64 offset,
                                      struct rb_node **next_ret,
                                      struct rb_node **prev_ret,
@@ -1537,8 +1555,8 @@ out:
 }
 
 /**
- * find_first_clear_extent_bit - finds the first range that has @bits not set
- * and that starts after @start
+ * find_first_clear_extent_bit - find the first range that has @bits not set.
+ * This range could start before @start.
  *
  * @tree - the tree to search
  * @start - the offset at/after which the found extent should start
@@ -1578,12 +1596,52 @@ void find_first_clear_extent_bit(struct extent_io_tree *tree, u64 start,
                                goto out;
                        }
                }
+               /*
+                * At this point 'node' either contains 'start' or start is
+                * before 'node'
+                */
                state = rb_entry(node, struct extent_state, rb_node);
-               if (in_range(start, state->start, state->end - state->start + 1) &&
-                       (state->state & bits)) {
-                       start = state->end + 1;
+
+               if (in_range(start, state->start, state->end - state->start + 1)) {
+                       if (state->state & bits) {
+                               /*
+                                * |--range with bits sets--|
+                                *    |
+                                *    start
+                                */
+                               start = state->end + 1;
+                       } else {
+                               /*
+                                * 'start' falls within a range that doesn't
+                                * have the bits set, so take its start as
+                                * the beginning of the desired range
+                                *
+                                * |--range with bits cleared----|
+                                *      |
+                                *      start
+                                */
+                               *start_ret = state->start;
+                               break;
+                       }
                } else {
-                       *start_ret = start;
+                       /*
+                        * |---prev range---|---hole/unset---|---node range---|
+                        *                          |
+                        *                        start
+                        *
+                        *                        or
+                        *
+                        * |---hole/unset--||--first node--|
+                        * 0   |
+                        *    start
+                        */
+                       if (prev) {
+                               state = rb_entry(prev, struct extent_state,
+                                                rb_node);
+                               *start_ret = state->end + 1;
+                       } else {
+                               *start_ret = 0;
+                       }
                        break;
                }
        }
@@ -3204,21 +3262,10 @@ static inline void contiguous_readpages(struct extent_io_tree *tree,
                                             unsigned long *bio_flags,
                                             u64 *prev_em_start)
 {
-       struct inode *inode;
-       struct btrfs_ordered_extent *ordered;
+       struct btrfs_inode *inode = BTRFS_I(pages[0]->mapping->host);
        int index;
 
-       inode = pages[0]->mapping->host;
-       while (1) {
-               lock_extent(tree, start, end);
-               ordered = btrfs_lookup_ordered_range(BTRFS_I(inode), start,
-                                                    end - start + 1);
-               if (!ordered)
-                       break;
-               unlock_extent(tree, start, end);
-               btrfs_start_ordered_extent(inode, ordered, 1);
-               btrfs_put_ordered_extent(ordered);
-       }
+       btrfs_lock_and_flush_ordered_range(tree, inode, start, end, NULL);
 
        for (index = 0; index < nr_pages; index++) {
                __do_readpage(tree, pages[index], btrfs_get_extent, em_cached,
@@ -3234,22 +3281,12 @@ static int __extent_read_full_page(struct extent_io_tree *tree,
                                   unsigned long *bio_flags,
                                   unsigned int read_flags)
 {
-       struct inode *inode = page->mapping->host;
-       struct btrfs_ordered_extent *ordered;
+       struct btrfs_inode *inode = BTRFS_I(page->mapping->host);
        u64 start = page_offset(page);
        u64 end = start + PAGE_SIZE - 1;
        int ret;
 
-       while (1) {
-               lock_extent(tree, start, end);
-               ordered = btrfs_lookup_ordered_range(BTRFS_I(inode), start,
-                                               PAGE_SIZE);
-               if (!ordered)
-                       break;
-               unlock_extent(tree, start, end);
-               btrfs_start_ordered_extent(inode, ordered, 1);
-               btrfs_put_ordered_extent(ordered);
-       }
+       btrfs_lock_and_flush_ordered_range(tree, inode, start, end, NULL);
 
        ret = __do_readpage(tree, page, get_extent, NULL, bio, mirror_num,
                            bio_flags, read_flags, NULL);
@@ -3310,7 +3347,6 @@ static noinline_for_stack int writepage_delalloc(struct inode *inode,
                }
                ret = btrfs_run_delalloc_range(inode, page, delalloc_start,
                                delalloc_end, &page_started, nr_written, wbc);
-               /* File system has been set read-only */
                if (ret) {
                        SetPageError(page);
                        /*
@@ -4542,6 +4578,8 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
        struct btrfs_path *path;
        struct btrfs_root *root = BTRFS_I(inode)->root;
        struct fiemap_cache cache = { 0 };
+       struct ulist *roots;
+       struct ulist *tmp_ulist;
        int end = 0;
        u64 em_start = 0;
        u64 em_len = 0;
@@ -4555,6 +4593,13 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
                return -ENOMEM;
        path->leave_spinning = 1;
 
+       roots = ulist_alloc(GFP_KERNEL);
+       tmp_ulist = ulist_alloc(GFP_KERNEL);
+       if (!roots || !tmp_ulist) {
+               ret = -ENOMEM;
+               goto out_free_ulist;
+       }
+
        start = round_down(start, btrfs_inode_sectorsize(inode));
        len = round_up(max, btrfs_inode_sectorsize(inode)) - start;
 
@@ -4566,7 +4611,7 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
                        btrfs_ino(BTRFS_I(inode)), -1, 0);
        if (ret < 0) {
                btrfs_free_path(path);
-               return ret;
+               goto out_free_ulist;
        } else {
                WARN_ON(!ret);
                if (ret == 1)
@@ -4675,7 +4720,7 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
                         */
                        ret = btrfs_check_shared(root,
                                                 btrfs_ino(BTRFS_I(inode)),
-                                                bytenr);
+                                                bytenr, roots, tmp_ulist);
                        if (ret < 0)
                                goto out_free;
                        if (ret)
@@ -4721,6 +4766,10 @@ out:
        btrfs_free_path(path);
        unlock_extent_cached(&BTRFS_I(inode)->io_tree, start, start + len - 1,
                             &cached_state);
+
+out_free_ulist:
+       ulist_free(roots);
+       ulist_free(tmp_ulist);
        return ret;
 }