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authorJeff Layton <jlayton@redhat.com>2017-07-31 10:29:38 -0400
committerJeff Layton <jlayton@redhat.com>2017-08-01 08:39:29 -0400
commitffb959bbdf923b4f89a08a04aba2501b1b16d164 (patch)
treefa248b66c3b36982ee41ca1c51807b453b4d9e22 /mm/filemap.c
parent3b49c9a1e984b524142afc7536041d8c66877113 (diff)
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 <marcelo.tosatti@cyclades.com> 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 <jack@suse.cz> Signed-off-by: Jeff Layton <jlayton@redhat.com>
Diffstat (limited to 'mm/filemap.c')
-rw-r--r--mm/filemap.c30
1 files changed, 1 insertions, 29 deletions
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) ||