diff options
| -rw-r--r-- | mm/readahead.c | 33 |
1 files changed, 23 insertions, 10 deletions
diff --git a/mm/readahead.c b/mm/readahead.c index 4a58befbde4..fd588ffc508 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -380,6 +380,29 @@ ondemand_readahead(struct address_space *mapping, } /* + * Hit a marked page without valid readahead state. + * E.g. interleaved reads. + * Query the pagecache for async_size, which normally equals to + * readahead size. Ramp it up and use it as the new readahead size. + */ + if (hit_readahead_marker) { + pgoff_t start; + + read_lock_irq(&mapping->tree_lock); + start = radix_tree_next_hole(&mapping->page_tree, offset, max+1); + read_unlock_irq(&mapping->tree_lock); + + if (!start || start - offset > max) + return 0; + + ra->start = start; + ra->size = start - offset; /* old async_size */ + ra->size = get_next_ra_size(ra, max); + ra->async_size = ra->size; + goto readit; + } + + /* * It may be one of * - first read on start of file * - sequential cache miss @@ -390,16 +413,6 @@ ondemand_readahead(struct address_space *mapping, ra->size = get_init_ra_size(req_size, max); ra->async_size = ra->size > req_size ? ra->size - req_size : ra->size; - /* - * Hit on a marked page without valid readahead state. - * E.g. interleaved reads. - * Not knowing its readahead pos/size, bet on the minimal possible one. - */ - if (hit_readahead_marker) { - ra->start++; - ra->size = get_next_ra_size(ra, max); - } - readit: return ra_submit(ra, mapping, filp); } |