Derived from Jan's patch:http://permalink.gmane.org/gmane.comp.file-systems.ext4/36470 Merging of uninitialized extents creates all sorts of interesting race possibilities when writeback / DIO races with fallocate. Thus ext4_convert_unwritten_extents_endio() has to deal with a case where extent to be converted needs to be split out first. That isn't nice for two reasons: 1) It may need allocation of extent tree block so ENOSPC is possible. 2) It complicates end_io handling code So we disable merging of uninitialized extents which allows us to simplify the code. Extents will get merged after they are converted to initialized ones. Signed-off-by: Dmitry Monakhov <dmonakhov@xxxxxxxxxx> --- fs/ext4/extents.c | 8 +++++--- 1 files changed, 5 insertions(+), 3 deletions(-) diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 3bd3ca5..1d37f2d 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -1584,10 +1584,12 @@ ext4_can_extents_be_merged(struct inode *inode, struct ext4_extent *ex1, unsigned short ext1_ee_len, ext2_ee_len, max_len; /* - * Make sure that either both extents are uninitialized, or - * both are _not_. + * Make sure that both extents are initialized. We don't merge + * uninitialized extents so that we can be sure that end_io code has + * the extent that was written properly split out and conversion to + * initialized is trivial. */ - if (ext4_ext_is_uninitialized(ex1) ^ ext4_ext_is_uninitialized(ex2)) + if (ext4_ext_is_uninitialized(ex1) || ext4_ext_is_uninitialized(ex2)) return 0; if (ext4_ext_is_uninitialized(ex1)) -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
