ext4: Fix hueristic which avoids group preallocation for closed files

The hueristic was designed to avoid using locality group preallocation
when writing the last segment of a closed file.  Fix it by move
setting size to the maximum of size and isize until after we check
whether size == isize.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index e9c6189..c73d439 100644 (file)
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4189,7 +4189,6 @@ static void ext4_mb_group_or_file(struct ext4_allocation_context *ac)
        size = ac->ac_o_ex.fe_logical + ac->ac_o_ex.fe_len;
        isize = (i_size_read(ac->ac_inode) + ac->ac_sb->s_blocksize - 1)
                >> bsbits;
-       size = max(size, isize);
 
        if ((size == isize) &&
            !ext4_fs_is_busy(sbi) &&
@@ -4199,6 +4198,7 @@ static void ext4_mb_group_or_file(struct ext4_allocation_context *ac)
        }
 
        /* don't use group allocation for large files */
+       size = max(size, isize);
        if (size >= sbi->s_mb_stream_request) {
                ac->ac_flags |= EXT4_MB_STREAM_ALLOC;
                return;