From: Qu Wenruo Date: Mon, 28 Jul 2025 08:27:56 +0000 (+0930) Subject: btrfs: make nocow_one_range() to do cleanup on error X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=13141df705b7145e46b88b1147d67d7a43f2d9e8;p=users%2Fhch%2Fmisc.git 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 Signed-off-by: David Sterba --- diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 56f56206a832..80e02b49b3a9 100644 --- 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) { /*