tree 883dc6e8433bbe315fa8fce00154d51ac52b3dd7
parent e3fb8eb14eafd2847c04cf48b52a705c36f4db98
author Jan Kara <jack@suse.cz> 1457583073 -0500
committer Theodore Ts'o <tytso@mit.edu> 1457583073 -0500

ext4: more efficient SEEK_DATA implementation

Using SEEK_DATA in a huge sparse file can easily lead to sotflockups as
ext4_seek_data() iterates hole block-by-block. Fix the problem by using
returned hole size from ext4_map_blocks() and thus skip the hole in one
go.

Update also SEEK_HOLE implementation to follow the same pattern as
SEEK_DATA to make future maintenance easier.

Furthermore we add cond_resched() to both ext4_seek_data() and
ext4_seek_hole() to avoid softlockups in case evil user creates huge
fragmented file and we have to go through lots of extents.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>