Man page 9 : page_cache_sync_readahead

page_cache_sync_readahead - generic file readahead

void page_cache_sync_readahead(struct address_space *  mapping , struct file_ra_state *  ra , struct file *  filp , pgoff_t  offset , unsigned long  req_size );

mapping
    address_space which holds the pagecache and I/O vectors

ra
    file_ra_state which holds the readahead state

filp
    passed on to ->readpage and ->readpages

offset
    start offset into mapping, in pagecache page-sized units

req_size
    hint: total size of the read which the caller is performing in pagecache pages

page_cache_sync_readahead should be called when a cache miss happened: it will submit the read. The readahead logic may decide to piggyback more pages onto the read request if access patterns suggest it will improve performance.