1 files changed, 34 insertions, 7 deletions

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index bf3f424e0013..4ebabd237153 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -595,9 +595,14 @@ int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
                 clear = 1;
 again:
         if (!prealloc && (mask & __GFP_WAIT)) {
+                /*
+                 * Don't care for allocation failure here because we might end
+                 * up not needing the pre-allocated extent state at all, which
+                 * is the case if we only have in the tree extent states that
+                 * cover our input range and don't cover too any other range.
+                 * If we end up needing a new extent state we allocate it later.
+                 */
                 prealloc = alloc_extent_state(mask);
-                if (!prealloc)
-                        return -ENOMEM;
         }
 
         spin_lock(&tree->lock);
@@ -796,17 +801,25 @@ static void set_state_bits(struct extent_io_tree *tree,
         state->state |= bits_to_set;
 }
 
-static void cache_state(struct extent_state *state,
-                        struct extent_state **cached_ptr)
+static void cache_state_if_flags(struct extent_state *state,
+                                 struct extent_state **cached_ptr,
+                                 const u64 flags)
 {
         if (cached_ptr && !(*cached_ptr)) {
-                if (state->state & (EXTENT_IOBITS | EXTENT_BOUNDARY)) {
+                if (!flags || (state->state & flags)) {
                         *cached_ptr = state;
                         atomic_inc(&state->refs);
                 }
         }
 }
 
+static void cache_state(struct extent_state *state,
+                        struct extent_state **cached_ptr)
+{
+        return cache_state_if_flags(state, cached_ptr,
+                                    EXTENT_IOBITS | EXTENT_BOUNDARY);
+}
+
 /*
  * set some bits on a range in the tree.  This may require allocations or
  * sleeping, so the gfp mask is used to indicate what is allowed.
@@ -1058,13 +1071,21 @@ int convert_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
         int err = 0;
         u64 last_start;
         u64 last_end;
+        bool first_iteration = true;
 
         btrfs_debug_check_extent_io_range(tree, start, end);
 
 again:
         if (!prealloc && (mask & __GFP_WAIT)) {
+                /*
+                 * Best effort, don't worry if extent state allocation fails
+                 * here for the first iteration. We might have a cached state
+                 * that matches exactly the target range, in which case no
+                 * extent state allocations are needed. We'll only know this
+                 * after locking the tree.
+                 */
                 prealloc = alloc_extent_state(mask);
-                if (!prealloc)
+                if (!prealloc && !first_iteration)
                         return -ENOMEM;
         }
 
@@ -1234,6 +1255,7 @@ search_again:
         spin_unlock(&tree->lock);
         if (mask & __GFP_WAIT)
                 cond_resched();
+        first_iteration = false;
         goto again;
 }
 
@@ -1482,7 +1504,7 @@ int find_first_extent_bit(struct extent_io_tree *tree, u64 start,
         state = find_first_extent_bit_state(tree, start, bits);
 got_it:
         if (state) {
-                cache_state(state, cached_state);
+                cache_state_if_flags(state, cached_state, 0);
                 *start_ret = state->start;
                 *end_ret = state->end;
                 ret = 0;
@@ -1746,6 +1768,9 @@ int extent_clear_unlock_delalloc(struct inode *inode, u64 start, u64 end,
         if (page_ops == 0)
                 return 0;
 
+        if ((page_ops & PAGE_SET_ERROR) && nr_pages > 0)
+                mapping_set_error(inode->i_mapping, -EIO);
+
         while (nr_pages > 0) {
                 ret = find_get_pages_contig(inode->i_mapping, index,
                                      min_t(unsigned long,
@@ -1763,6 +1788,8 @@ int extent_clear_unlock_delalloc(struct inode *inode, u64 start, u64 end,
                                 clear_page_dirty_for_io(pages[i]);
                         if (page_ops & PAGE_SET_WRITEBACK)
                                 set_page_writeback(pages[i]);
+                        if (page_ops & PAGE_SET_ERROR)
+                                SetPageError(pages[i]);
                         if (page_ops & PAGE_END_WRITEBACK)
                                 end_page_writeback(pages[i]);
                         if (page_ops & PAGE_UNLOCK)