file->f_ra->ra_pages will remain the initialized value since it opend, which may be NOT equal to bdi->ra_pages as the latter one is updated somehow(etc, echo xxx > /sys/block/dm/queue/read_ahead_kb).So having readahead use bdi->ra_pages.
Signed-off-by: Zhaoyang Huang <[email protected]> --- mm/filemap.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index d78f577..259dcfd 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2499,8 +2499,8 @@ static struct file *do_sync_mmap_readahead(struct vm_fault *vmf) */ fpin = maybe_unlock_mmap_for_io(vmf, fpin); ra->start = max_t(long, 0, offset - ra->ra_pages / 2); - ra->size = ra->ra_pages; - ra->async_size = ra->ra_pages / 4; + ra->size = inode_to_bdi(mapping->host)->ra_pages; + ra->async_size = ra->size / 4; ra_submit(ra, mapping, file); return fpin; } -- 1.9.1
