btrfs: make nocow_one_range() to do cleanup on error

Currently if we hit an error inside nocow_one_range(), we do not clear
the page dirty, and let the caller to handle it.

This is very different compared to fallback_to_cow(), when that function
failed, everything will be cleaned up by cow_file_range().

Enhance the situation by:

- Use a common error handling for nocow_one_range()
  If we failed anything, use the same btrfs_cleanup_ordered_extents()
  and extent_clear_unlock_delalloc().

  btrfs_cleanup_ordered_extents() is safe even if we haven't created new
  ordered extent, in that case there should be no OE and that function
  will do nothing.

  The same applies to extent_clear_unlock_delalloc(), and since we're
  passing PAGE_UNLOCK | PAGE_START_WRITEBACK | PAGE_END_WRITEBACK, it
  will also clear folio dirty flag during error handling.

- Avoid touching the failed range of nocow_one_range()
  As the failed range will be cleaned up and unlocked by that function.

  Here we introduce a new variable @nocow_end to record the failed range,
  so that we can skip it during the error handling of run_delalloc_nocow().

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 56f56206a83293e2f7eee3120faa8d60c1754a96..80e02b49b3a945acc3dde117fadce343b8f9a626 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1982,8 +1982,8 @@ static int nocow_one_range(struct btrfs_inode *inode, struct folio *locked_folio
                em = btrfs_create_io_em(inode, file_pos, &nocow_args->file_extent,
                                        BTRFS_ORDERED_PREALLOC);
                if (IS_ERR(em)) {
-                       btrfs_unlock_extent(&inode->io_tree, file_pos, end, cached);
-                       return PTR_ERR(em);
+                       ret = PTR_ERR(em);
+                       goto error;
                }
                btrfs_free_extent_map(em);
        }
@@ -1995,8 +1995,8 @@ static int nocow_one_range(struct btrfs_inode *inode, struct folio *locked_folio
        if (IS_ERR(ordered)) {
                if (is_prealloc)
                        btrfs_drop_extent_map_range(inode, file_pos, end, false);
-               btrfs_unlock_extent(&inode->io_tree, file_pos, end, cached);
-               return PTR_ERR(ordered);
+               ret = PTR_ERR(ordered);
+               goto error;
        }
 
        if (btrfs_is_data_reloc_root(inode->root))
@@ -2008,23 +2008,25 @@ static int nocow_one_range(struct btrfs_inode *inode, struct folio *locked_folio
                ret = btrfs_reloc_clone_csums(ordered);
        btrfs_put_ordered_extent(ordered);
 
+       if (ret < 0)
+               goto error;
        extent_clear_unlock_delalloc(inode, file_pos, end, locked_folio, cached,
                                     EXTENT_LOCKED | EXTENT_DELALLOC |
                                     EXTENT_CLEAR_DATA_RESV,
                                     PAGE_UNLOCK | PAGE_SET_ORDERED);
-       /*
-        * On error, we need to cleanup the ordered extents we created.
-        *
-        * We do not clear the folio Dirty flags because they are set and
-        * cleaered by the caller.
-        */
-       if (ret < 0) {
-               btrfs_cleanup_ordered_extents(inode, file_pos, len);
-               btrfs_err(inode->root->fs_info,
-                         "%s failed, root=%lld inode=%llu start=%llu len=%llu: %d",
-                         __func__, btrfs_root_id(inode->root), btrfs_ino(inode),
-                         file_pos, len, ret);
-       }
+       return ret;
+
+error:
+       btrfs_cleanup_ordered_extents(inode, file_pos, len);
+       extent_clear_unlock_delalloc(inode, file_pos, end, locked_folio, cached,
+                                    EXTENT_LOCKED | EXTENT_DELALLOC |
+                                    EXTENT_CLEAR_DATA_RESV,
+                                    PAGE_UNLOCK | PAGE_START_WRITEBACK |
+                                    PAGE_END_WRITEBACK);
+       btrfs_err(inode->root->fs_info,
+                 "%s failed, root=%lld inode=%llu start=%llu len=%llu: %d",
+                 __func__, btrfs_root_id(inode->root), btrfs_ino(inode),
+                 file_pos, len, ret);
        return ret;
 }
 
@@ -2046,8 +2048,12 @@ static noinline int run_delalloc_nocow(struct btrfs_inode *inode,
        /*
         * If not 0, represents the inclusive end of the last fallback_to_cow()
         * range. Only for error handling.
+        *
+        * The same for nocow_end, it's to avoid double cleaning up the range
+        * already cleaned by nocow_one_range().
         */
        u64 cow_end = 0;
+       u64 nocow_end = 0;
        u64 cur_offset = start;
        int ret;
        bool check_prev = true;
@@ -2222,8 +2228,10 @@ must_cow:
                                      &nocow_args, cur_offset,
                                      extent_type == BTRFS_FILE_EXTENT_PREALLOC);
                btrfs_dec_nocow_writers(nocow_bg);
-               if (ret < 0)
+               if (ret < 0) {
+                       nocow_end = cur_offset + nocow_args.file_extent.num_bytes - 1;
                        goto error;
+               }
                cur_offset = extent_end;
        }
        btrfs_release_path(path);
@@ -2250,12 +2258,22 @@ error:
                 *    start           cur_offset               end
                 *    |   OE cleanup  |       Untouched        |
                 *
-                * We finished a fallback_to_cow() or nocow_one_range() call, but
-                * failed to check the next range.
+                * We finished a fallback_to_cow() or nocow_one_range() call,
+                * but failed to check the next range.
+                *
+                * or
+                *    start           cur_offset   nocow_end   end
+                *    |   OE cleanup  |   Skip     | Untouched |
+                *
+                * nocow_one_range() failed, the range [cur_offset, nocow_end] is
+                * alread cleaned up.
                 */
                oe_cleanup_start = start;
                oe_cleanup_len = cur_offset - start;
-               untouched_start = cur_offset;
+               if (nocow_end)
+                       untouched_start = nocow_end + 1;
+               else
+                       untouched_start = cur_offset;
                untouched_len = end + 1 - untouched_start;
        } else if (cow_start != (u64)-1 && cow_end == 0) {
                /*