On a read-only filesystem, we won't invoke the block allocator, so we don't need to prefetch the block bitmaps. This avoids starting and running the ext4lazyinit thread at all on a system with no read-write ext4 filesystems (for instance, a container VM with read-only filesystems underneath an overlayfs). Fixes: 21175ca434c5 ("ext4: make prefetch_block_bitmaps default") Signed-off-by: Josh Triplett <josh@xxxxxxxxxxxxxxxx> --- Tested in a VM, with a read-only ext4 root filesystem. Confirmed that ext4lazyinit starts without this patch, and does not start with this patch. (For a future merge window, not the current one. Please let me know if I need to re-send this at a later, more convenient time.) fs/ext4/super.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 845f2f8aee5f..20437acc8865 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -3973,9 +3973,9 @@ int ext4_register_li_request(struct super_block *sb, goto out; } - if (test_opt(sb, NO_PREFETCH_BLOCK_BITMAPS) && - (first_not_zeroed == ngroups || sb_rdonly(sb) || - !test_opt(sb, INIT_INODE_TABLE))) + if (sb_rdonly(sb) || + (test_opt(sb, NO_PREFETCH_BLOCK_BITMAPS) && + (first_not_zeroed == ngroups || !test_opt(sb, INIT_INODE_TABLE)))) goto out; elr = ext4_li_request_new(sb, first_not_zeroed); -- 2.36.1