1 files changed, 167 insertions, 46 deletions

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 5e76a474cb7e..714adc4ac4c2 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -1433,12 +1433,13 @@ int extent_clear_unlock_delalloc(struct inode *inode,
  */
 u64 count_range_bits(struct extent_io_tree *tree,
                      u64 *start, u64 search_end, u64 max_bytes,
-                     unsigned long bits)
+                     unsigned long bits, int contig)
 {
         struct rb_node *node;
         struct extent_state *state;
         u64 cur_start = *start;
         u64 total_bytes = 0;
+        u64 last = 0;
         int found = 0;
 
         if (search_end <= cur_start) {
@@ -1463,7 +1464,9 @@ u64 count_range_bits(struct extent_io_tree *tree,
                 state = rb_entry(node, struct extent_state, rb_node);
                 if (state->start > search_end)
                         break;
-                if (state->end >= cur_start && (state->state & bits)) {
+                if (contig && found && state->start > last + 1)
+                        break;
+                if (state->end >= cur_start && (state->state & bits) == bits) {
                         total_bytes += min(search_end, state->end) + 1 -
                                        max(cur_start, state->start);
                         if (total_bytes >= max_bytes)
@@ -1472,6 +1475,9 @@ u64 count_range_bits(struct extent_io_tree *tree,
                                 *start = state->start;
                                 found = 1;
                         }
+                        last = state->end;
+                } else if (contig && found) {
+                        break;
                 }
                 node = rb_next(node);
                 if (!node)
@@ -1946,6 +1952,7 @@ void set_page_extent_mapped(struct page *page)
 
 static void set_page_extent_head(struct page *page, unsigned long len)
 {
+        WARN_ON(!PagePrivate(page));
         set_page_private(page, EXTENT_PAGE_PRIVATE_FIRST_PAGE | len << 2);
 }
 
@@ -2821,9 +2828,17 @@ int try_release_extent_state(struct extent_map_tree *map,
                  * at this point we can safely clear everything except the
                  * locked bit and the nodatasum bit
                  */
-                clear_extent_bit(tree, start, end,
+                ret = clear_extent_bit(tree, start, end,
                                  ~(EXTENT_LOCKED | EXTENT_NODATASUM),
                                  0, 0, NULL, mask);
+
+                /* if clear_extent_bit failed for enomem reasons,
+                 * we can't allow the release to continue.
+                 */
+                if (ret < 0)
+                        ret = 0;
+                else
+                        ret = 1;
         }
         return ret;
 }
@@ -2903,6 +2918,46 @@ out:
         return sector;
 }
 
+/*
+ * helper function for fiemap, which doesn't want to see any holes.
+ * This maps until we find something past 'last'
+ */
+static struct extent_map *get_extent_skip_holes(struct inode *inode,
+                                                u64 offset,
+                                                u64 last,
+                                                get_extent_t *get_extent)
+{
+        u64 sectorsize = BTRFS_I(inode)->root->sectorsize;
+        struct extent_map *em;
+        u64 len;
+
+        if (offset >= last)
+                return NULL;
+
+        while(1) {
+                len = last - offset;
+                if (len == 0)
+                        break;
+                len = (len + sectorsize - 1) & ~(sectorsize - 1);
+                em = get_extent(inode, NULL, 0, offset, len, 0);
+                if (!em || IS_ERR(em))
+                        return em;
+
+                /* if this isn't a hole return it */
+                if (!test_bit(EXTENT_FLAG_VACANCY, &em->flags) &&
+                    em->block_start != EXTENT_MAP_HOLE) {
+                        return em;
+                }
+
+                /* this is a hole, advance to the next extent */
+                offset = extent_map_end(em);
+                free_extent_map(em);
+                if (offset >= last)
+                        break;
+        }
+        return NULL;
+}
+
 int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
                 __u64 start, __u64 len, get_extent_t *get_extent)
 {
@@ -2912,16 +2967,19 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
         u32 flags = 0;
         u32 found_type;
         u64 last;
+        u64 last_for_get_extent = 0;
         u64 disko = 0;
+        u64 isize = i_size_read(inode);
         struct btrfs_key found_key;
         struct extent_map *em = NULL;
         struct extent_state *cached_state = NULL;
         struct btrfs_path *path;
         struct btrfs_file_extent_item *item;
         int end = 0;
-        u64 em_start = 0, em_len = 0;
+        u64 em_start = 0;
+        u64 em_len = 0;
+        u64 em_end = 0;
         unsigned long emflags;
-        int hole = 0;
 
         if (len == 0)
                 return -EINVAL;
@@ -2931,6 +2989,10 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
                 return -ENOMEM;
         path->leave_spinning = 1;
 
+        /*
+         * lookup the last file extent.  We're not using i_size here
+         * because there might be preallocation past i_size
+         */
         ret = btrfs_lookup_file_extent(NULL, BTRFS_I(inode)->root,
                                        path, inode->i_ino, -1, 0);
         if (ret < 0) {
@@ -2944,18 +3006,38 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
         btrfs_item_key_to_cpu(path->nodes[0], &found_key, path->slots[0]);
         found_type = btrfs_key_type(&found_key);
 
-        /* No extents, just return */
+        /* No extents, but there might be delalloc bits */
         if (found_key.objectid != inode->i_ino ||
             found_type != BTRFS_EXTENT_DATA_KEY) {
-                btrfs_free_path(path);
-                return 0;
+                /* have to trust i_size as the end */
+                last = (u64)-1;
+                last_for_get_extent = isize;
+        } else {
+                /*
+                 * remember the start of the last extent.  There are a
+                 * bunch of different factors that go into the length of the
+                 * extent, so its much less complex to remember where it started
+                 */
+                last = found_key.offset;
+                last_for_get_extent = last + 1;
         }
-        last = found_key.offset;
         btrfs_free_path(path);
 
+        /*
+         * we might have some extents allocated but more delalloc past those
+         * extents.  so, we trust isize unless the start of the last extent is
+         * beyond isize
+         */
+        if (last < isize) {
+                last = (u64)-1;
+                last_for_get_extent = isize;
+        }
+
         lock_extent_bits(&BTRFS_I(inode)->io_tree, start, start + len, 0,
                          &cached_state, GFP_NOFS);
-        em = get_extent(inode, NULL, 0, off, max - off, 0);
+
+        em = get_extent_skip_holes(inode, off, last_for_get_extent,
+                                   get_extent);
         if (!em)
                 goto out;
         if (IS_ERR(em)) {
@@ -2964,22 +3046,38 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
         }
 
         while (!end) {
-                hole = 0;
-                off = em->start + em->len;
-                if (off >= max)
-                        end = 1;
+                u64 offset_in_extent;
 
-                if (em->block_start == EXTENT_MAP_HOLE) {
-                        hole = 1;
-                        goto next;
-                }
+                /* break if the extent we found is outside the range */
+                if (em->start >= max || extent_map_end(em) < off)
+                        break;
 
-                em_start = em->start;
-                em_len = em->len;
+                /*
+                 * get_extent may return an extent that starts before our
+                 * requested range.  We have to make sure the ranges
+                 * we return to fiemap always move forward and don't
+                 * overlap, so adjust the offsets here
+                 */
+                em_start = max(em->start, off);
 
+                /*
+                 * record the offset from the start of the extent
+                 * for adjusting the disk offset below
+                 */
+                offset_in_extent = em_start - em->start;
+                em_end = extent_map_end(em);
+                em_len = em_end - em_start;
+                emflags = em->flags;
                 disko = 0;
                 flags = 0;
 
+                /*
+                 * bump off for our next call to get_extent
+                 */
+                off = extent_map_end(em);
+                if (off >= max)
+                        end = 1;
+
                 if (em->block_start == EXTENT_MAP_LAST_BYTE) {
                         end = 1;
                         flags |= FIEMAP_EXTENT_LAST;
@@ -2990,42 +3088,34 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
                         flags |= (FIEMAP_EXTENT_DELALLOC |
                                   FIEMAP_EXTENT_UNKNOWN);
                 } else {
-                        disko = em->block_start;
+                        disko = em->block_start + offset_in_extent;
                 }
                 if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
                         flags |= FIEMAP_EXTENT_ENCODED;
 
-next:
-                emflags = em->flags;
                 free_extent_map(em);
                 em = NULL;
-                if (!end) {
-                        em = get_extent(inode, NULL, 0, off, max - off, 0);
-                        if (!em)
-                                goto out;
-                        if (IS_ERR(em)) {
-                                ret = PTR_ERR(em);
-                                goto out;
-                        }
-                        emflags = em->flags;
-                }
-
-                if (test_bit(EXTENT_FLAG_VACANCY, &emflags)) {
+                if ((em_start >= last) || em_len == (u64)-1 ||
+                   (last == (u64)-1 && isize <= em_end)) {
                         flags |= FIEMAP_EXTENT_LAST;
                         end = 1;
                 }
 
-                if (em_start == last) {
+                /* now scan forward to see if this is really the last extent. */
+                em = get_extent_skip_holes(inode, off, last_for_get_extent,
+                                           get_extent);
+                if (IS_ERR(em)) {
+                        ret = PTR_ERR(em);
+                        goto out;
+                }
+                if (!em) {
                         flags |= FIEMAP_EXTENT_LAST;
                         end = 1;
                 }
-
-                if (!hole) {
-                        ret = fiemap_fill_next_extent(fieinfo, em_start, disko,
-                                                em_len, flags);
-                        if (ret)
-                                goto out_free;
-                }
+                ret = fiemap_fill_next_extent(fieinfo, em_start, disko,
+                                              em_len, flags);
+                if (ret)
+                        goto out_free;
         }
 out_free:
         free_extent_map(em);
@@ -3194,7 +3284,13 @@ struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree,
                 }
                 if (!PageUptodate(p))
                         uptodate = 0;
-                unlock_page(p);
+
+                /*
+                 * see below about how we avoid a nasty race with release page
+                 * and why we unlock later
+                 */
+                if (i != 0)
+                        unlock_page(p);
         }
         if (uptodate)
                 set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
@@ -3218,9 +3314,26 @@ struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree,
         atomic_inc(&eb->refs);
         spin_unlock(&tree->buffer_lock);
         radix_tree_preload_end();
+
+        /*
+         * there is a race where release page may have
+         * tried to find this extent buffer in the radix
+         * but failed.  It will tell the VM it is safe to
+         * reclaim the, and it will clear the page private bit.
+         * We must make sure to set the page private bit properly
+         * after the extent buffer is in the radix tree so
+         * it doesn't get lost
+         */
+        set_page_extent_mapped(eb->first_page);
+        set_page_extent_head(eb->first_page, eb->len);
+        if (!page0)
+                unlock_page(eb->first_page);
         return eb;
 
 free_eb:
+        if (eb->first_page && !page0)
+                unlock_page(eb->first_page);
+
         if (!atomic_dec_and_test(&eb->refs))
                 return exists;
         btrfs_release_extent_buffer(eb);
@@ -3271,10 +3384,11 @@ int clear_extent_buffer_dirty(struct extent_io_tree *tree,
                         continue;
 
                 lock_page(page);
+                WARN_ON(!PagePrivate(page));
+
+                set_page_extent_mapped(page);
                 if (i == 0)
                         set_page_extent_head(page, eb->len);
-                else
-                        set_page_private(page, EXTENT_PAGE_PRIVATE);
 
                 clear_page_dirty_for_io(page);
                 spin_lock_irq(&page->mapping->tree_lock);
@@ -3464,6 +3578,13 @@ int read_extent_buffer_pages(struct extent_io_tree *tree,
 
         for (i = start_i; i < num_pages; i++) {
                 page = extent_buffer_page(eb, i);
+
+                WARN_ON(!PagePrivate(page));
+
+                set_page_extent_mapped(page);
+                if (i == 0)
+                        set_page_extent_head(page, eb->len);
+
                 if (inc_all_pages)
                         page_cache_get(page);
                 if (!PageUptodate(page)) {