ext4: always set then trimmed blocks count into len

Currently if the range to trim is too small, for example on 1K fs
the request to trim the first block, then the 'range->len' is not set
reporting wrong number of discarded block to the caller.

Fix this by always setting the 'range->len' before we return. Note that
when there is a failure (-EINVAL) caller can not depend on 'range->len'
being set properly.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index c8b6a8808166e6fc14380f11358038ca33afc52d..99ab428bcfa089822e74b433aee7b1bf4076e34d 100644 (file)
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -5035,11 +5035,11 @@ int ext4_trim_fs(struct super_block *sb, struct fstrim_range *range)
                 */
                first_cluster = 0;
        }
-       range->len = trimmed * sb->s_blocksize;
 
        if (!ret)
                atomic_set(&EXT4_SB(sb)->s_last_trim_minblks, minlen);
 
 out:
+       range->len = trimmed * sb->s_blocksize;
        return ret;
 }