fs/dax.c: fix inefficiency in dax_writeback_mapping_range()

jankara · torvalds · commit 1eb643d02b21 · 2017-06-23T16:15:55.000-07:00
dax_writeback_mapping_range() fails to update iteration index when searching radix tree for entries needing cache flushing. Thus each pagevec worth of entries is searched starting from the start which is inefficient and prone to livelocks. Update index properly. Link: http://lkml.kernel.org/r/20170619124531.21491-1-jack@suse.cz Fixes: 9973c98 ("dax: add support for fsync/sync") Signed-off-by: Jan Kara <jack@suse.cz> Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/dax.c b/fs/dax.c
@@ -859,6 +859,7 @@ int dax_writeback_mapping_range(struct address_space *mapping,
 			if (ret < 0)
 				goto out;
 		}
+		start_index = indices[pvec.nr - 1] + 1;
 	}
 out:
 	put_dax(dax_dev);

Original file line number	Diff line number	Diff line change
`@@ -859,6 +859,7 @@ int dax_writeback_mapping_range(struct address_space *mapping,`
`859`	`859`	`if (ret < 0)`
`860`	`860`	`goto out;`
`861`	`861`	`}`
	`862`	`+ start_index = indices[pvec.nr - 1] + 1;`
`862`	`863`	`}`
`863`	`864`	`out:`
`864`	`865`	`put_dax(dax_dev);`