2 files changed, 45 insertions, 18 deletions

diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index 3e4fad4a909d..48a30d0e71fb 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -14,7 +14,7 @@
 #define EXTENT_DEFRAG           (1U << 6)
 #define EXTENT_BOUNDARY         (1U << 9)
 #define EXTENT_NODATASUM        (1U << 10)
-#define EXTENT_DO_ACCOUNTING    (1U << 11)
+#define EXTENT_CLEAR_META_RESV  (1U << 11)
 #define EXTENT_FIRST_DELALLOC   (1U << 12)
 #define EXTENT_NEED_WAIT        (1U << 13)
 #define EXTENT_DAMAGED          (1U << 14)
@@ -22,6 +22,8 @@
 #define EXTENT_QGROUP_RESERVED  (1U << 16)
 #define EXTENT_CLEAR_DATA_RESV  (1U << 17)
 #define EXTENT_IOBITS           (EXTENT_LOCKED | EXTENT_WRITEBACK)
+#define EXTENT_DO_ACCOUNTING    (EXTENT_CLEAR_META_RESV | \
+                                 EXTENT_CLEAR_DATA_RESV)
 #define EXTENT_CTLBITS          (EXTENT_DO_ACCOUNTING | EXTENT_FIRST_DELALLOC)
 
 /*
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index b8b2a3cbdbe1..bfe04afa6277 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -943,10 +943,13 @@ static noinline int cow_file_range(struct inode *inode,
         u64 num_bytes;
         unsigned long ram_size;
         u64 disk_num_bytes;
-        u64 cur_alloc_size;
+        u64 cur_alloc_size = 0;
         u64 blocksize = fs_info->sectorsize;
         struct btrfs_key ins;
         struct extent_map *em;
+        unsigned clear_bits;
+        unsigned long page_ops;
+        bool extent_reserved = false;
         int ret = 0;
 
         if (btrfs_is_free_space_inode(BTRFS_I(inode))) {
@@ -991,14 +994,14 @@ static noinline int cow_file_range(struct inode *inode,
                         start + num_bytes - 1, 0);
 
         while (disk_num_bytes > 0) {
-                unsigned long op;
-
                 cur_alloc_size = disk_num_bytes;
                 ret = btrfs_reserve_extent(root, cur_alloc_size, cur_alloc_size,
                                            fs_info->sectorsize, 0, alloc_hint,
                                            &ins, 1, 1);
                 if (ret < 0)
                         goto out_unlock;
+                cur_alloc_size = ins.offset;
+                extent_reserved = true;
 
                 ram_size = ins.offset;
                 em = create_io_em(inode, start, ins.offset, /* len */
@@ -1013,7 +1016,6 @@ static noinline int cow_file_range(struct inode *inode,
                         goto out_reserve;
                 free_extent_map(em);
 
-                cur_alloc_size = ins.offset;
                 ret = btrfs_add_ordered_extent(inode, start, ins.objectid,
                                                ram_size, cur_alloc_size, 0);
                 if (ret)
@@ -1048,14 +1050,14 @@ static noinline int cow_file_range(struct inode *inode,
                  * Do set the Private2 bit so we know this page was properly
                  * setup for writepage
                  */
-                op = unlock ? PAGE_UNLOCK : 0;
-                op |= PAGE_SET_PRIVATE2;
+                page_ops = unlock ? PAGE_UNLOCK : 0;
+                page_ops |= PAGE_SET_PRIVATE2;
 
                 extent_clear_unlock_delalloc(inode, start,
                                              start + ram_size - 1,
                                              delalloc_end, locked_page,
                                              EXTENT_LOCKED | EXTENT_DELALLOC,
-                                             op);
+                                             page_ops);
                 if (disk_num_bytes < cur_alloc_size)
                         disk_num_bytes = 0;
                 else
@@ -1063,6 +1065,7 @@ static noinline int cow_file_range(struct inode *inode,
                 num_bytes -= cur_alloc_size;
                 alloc_hint = ins.objectid + ins.offset;
                 start += cur_alloc_size;
+                extent_reserved = false;
 
                 /*
                  * btrfs_reloc_clone_csums() error, since start is increased
@@ -1081,12 +1084,35 @@ out_reserve:
         btrfs_dec_block_group_reservations(fs_info, ins.objectid);
         btrfs_free_reserved_extent(fs_info, ins.objectid, ins.offset, 1);
 out_unlock:
+        clear_bits = EXTENT_LOCKED | EXTENT_DELALLOC | EXTENT_DEFRAG |
+                EXTENT_CLEAR_META_RESV;
+        page_ops = PAGE_UNLOCK | PAGE_CLEAR_DIRTY | PAGE_SET_WRITEBACK |
+                PAGE_END_WRITEBACK;
+        /*
+         * If we reserved an extent for our delalloc range (or a subrange) and
+         * failed to create the respective ordered extent, then it means that
+         * when we reserved the extent we decremented the extent's size from
+         * the data space_info's bytes_may_use counter and incremented the
+         * space_info's bytes_reserved counter by the same amount. We must make
+         * sure extent_clear_unlock_delalloc() does not try to decrement again
+         * the data space_info's bytes_may_use counter, therefore we do not pass
+         * it the flag EXTENT_CLEAR_DATA_RESV.
+         */
+        if (extent_reserved) {
+                extent_clear_unlock_delalloc(inode, start,
+                                             start + cur_alloc_size,
+                                             start + cur_alloc_size,
+                                             locked_page,
+                                             clear_bits,
+                                             page_ops);
+                start += cur_alloc_size;
+                if (start >= end)
+                        goto out;
+        }
         extent_clear_unlock_delalloc(inode, start, end, delalloc_end,
                                      locked_page,
-                                     EXTENT_LOCKED | EXTENT_DO_ACCOUNTING |
-                                     EXTENT_DELALLOC | EXTENT_DEFRAG,
-                                     PAGE_UNLOCK | PAGE_CLEAR_DIRTY |
-                                     PAGE_SET_WRITEBACK | PAGE_END_WRITEBACK);
+                                     clear_bits | EXTENT_CLEAR_DATA_RESV,
+                                     page_ops);
         goto out;
 }
 
@@ -1776,7 +1802,7 @@ static void btrfs_clear_bit_hook(struct btrfs_inode *inode,
 
                 if (*bits & EXTENT_FIRST_DELALLOC) {
                         *bits &= ~EXTENT_FIRST_DELALLOC;
-                } else if (!(*bits & EXTENT_DO_ACCOUNTING)) {
+                } else if (!(*bits & EXTENT_CLEAR_META_RESV)) {
                         spin_lock(&inode->lock);
                         inode->outstanding_extents -= num_extents;
                         spin_unlock(&inode->lock);
@@ -1787,7 +1813,7 @@ static void btrfs_clear_bit_hook(struct btrfs_inode *inode,
                  * don't need to call dellalloc_release_metadata if there is an
                  * error.
                  */
-                if (*bits & EXTENT_DO_ACCOUNTING &&
+                if (*bits & EXTENT_CLEAR_META_RESV &&
                     root != fs_info->tree_root)
                         btrfs_delalloc_release_metadata(inode, len);
 
@@ -1795,10 +1821,9 @@ static void btrfs_clear_bit_hook(struct btrfs_inode *inode,
                 if (btrfs_is_testing(fs_info))
                         return;
 
-                if (root->root_key.objectid != BTRFS_DATA_RELOC_TREE_OBJECTID
-                    && do_list && !(state->state & EXTENT_NORESERVE)
-                    && (*bits & (EXTENT_DO_ACCOUNTING |
-                    EXTENT_CLEAR_DATA_RESV)))
+                if (root->root_key.objectid != BTRFS_DATA_RELOC_TREE_OBJECTID &&
+                    do_list && !(state->state & EXTENT_NORESERVE) &&
+                    (*bits & EXTENT_CLEAR_DATA_RESV))
                         btrfs_free_reserved_data_space_noquota(
                                         &inode->vfs_inode,
                                         state->start, len);