]> git.baikalelectronics.ru Git - kernel.git/commit
ext4: disable merging of uninitialized extents
authorDmitry Monakhov <dmonakhov@openvz.org>
Mon, 4 Mar 2013 05:36:06 +0000 (00:36 -0500)
committerTheodore Ts'o <tytso@mit.edu>
Mon, 4 Mar 2013 05:36:06 +0000 (00:36 -0500)
commitc39e381c084eb2dc27d3f2b1b230158d2988d6f1
treea04ffae5cd5f0d1724aa64f26046d5f85bb75af5
parentd88d4fcdf8807de97c3db5c1518fff9e40e9e8d4
ext4: disable merging of uninitialized extents

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@openvz.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
fs/ext4/extents.c