From ffb959bbdf923b4f89a08a04aba2501b1b16d164 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Mon, 31 Jul 2017 10:29:38 -0400 Subject: mm: remove optimizations based on i_size in mapping writeback waits Marcelo added this i_size based optimization with a patch in 2004 (commitid is from the linux-history tree): commit 765dad09b4ac101a32d87af2bb793c3060497d3c Author: Marcelo Tosatti Date: Tue Sep 7 17:51:17 2004 -0700 small wait_on_page_writeback_range() optimization filemap_fdatawait() calls wait_on_page_writeback_range() with -1 as "end" parameter. This is not needed since we know the EOF from the inode. Use that instead. There may be races here, particularly with clustered or network filesystems. It also seems like a bit of a layering violation since we're operating on an address_space here, not an inode. Finally, it's also questionable whether this optimization really helps on workloads that we care about. Should we be optimizing for writeback vs. truncate races in a codepath where we expect to wait anyway? It doesn't seem worth the risk. Remove this optimization from the filemap_fdatawait codepaths. This means that filemap_fdatawait becomes a trivial wrapper around filemap_fdatawait_range. Reviewed-by: Jan Kara Signed-off-by: Jeff Layton --- mm/filemap.c | 30 +----------------------------- 1 file changed, 1 insertion(+), 29 deletions(-) (limited to 'mm/filemap.c') diff --git a/mm/filemap.c b/mm/filemap.c index 394bb5e96f87..85dfe3bee324 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -512,39 +512,11 @@ EXPORT_SYMBOL(file_fdatawait_range); */ int filemap_fdatawait_keep_errors(struct address_space *mapping) { - loff_t i_size = i_size_read(mapping->host); - - if (i_size == 0) - return 0; - - __filemap_fdatawait_range(mapping, 0, i_size - 1); + __filemap_fdatawait_range(mapping, 0, LLONG_MAX); return filemap_check_and_keep_errors(mapping); } EXPORT_SYMBOL(filemap_fdatawait_keep_errors); -/** - * filemap_fdatawait - wait for all under-writeback pages to complete - * @mapping: address space structure to wait for - * - * Walk the list of under-writeback pages of the given address space - * and wait for all of them. Check error status of the address space - * and return it. - * - * Since the error status of the address space is cleared by this function, - * callers are responsible for checking the return value and handling and/or - * reporting the error. - */ -int filemap_fdatawait(struct address_space *mapping) -{ - loff_t i_size = i_size_read(mapping->host); - - if (i_size == 0) - return 0; - - return filemap_fdatawait_range(mapping, 0, i_size - 1); -} -EXPORT_SYMBOL(filemap_fdatawait); - static bool mapping_needs_writeback(struct address_space *mapping) { return (!dax_mapping(mapping) && mapping->nrpages) || -- cgit