diff options
| author | Markus Stockhausen <stockhausen@collogia.de> | 2018-07-27 09:09:53 -0600 |
|---|---|---|
| committer | Alistair Strachan <astrachan@google.com> | 2019-01-23 21:46:33 +0000 |
| commit | f2d65ea603e2043e80c63cf6dcd41d6a0ce8c841 (patch) | |
| tree | d2412f69d6ba6acbc5ed6c3f470d4bf4828c57c3 /mm/readahead.c | |
| parent | e7c8b35e486775af65636a2a2b2766c3def9a8e8 (diff) | |
UPSTREAM: readahead: stricter check for bdi io_pages
ondemand_readahead() checks bdi->io_pages to cap the maximum pages
that need to be processed. This works until the readit section. If
we would do an async only readahead (async size = sync size) and
target is at beginning of window we expand the pages by another
get_next_ra_size() pages. Btrace for large reads shows that kernel
always issues a doubled size read at the beginning of processing.
Add an additional check for io_pages in the lower part of the func.
The fix helps devices that hard limit bio pages and rely on proper
handling of max_hw_read_sectors (e.g. older FusionIO cards). For
that reason it could qualify for stable.
Fixes: 9491ae4a ("mm: don't cap request size based on read-ahead setting")
Change-Id: If111344b54897555085c2a6c442d697069962f11
Cc: stable@vger.kernel.org
Signed-off-by: Markus Stockhausen <stockhausen@collogia.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>
Diffstat (limited to 'mm/readahead.c')
| -rw-r--r-- | mm/readahead.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/mm/readahead.c b/mm/readahead.c index 920aa20de891..f230b942cda2 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -381,6 +381,7 @@ ondemand_readahead(struct address_space *mapping, { struct backing_dev_info *bdi = inode_to_bdi(mapping->host); unsigned long max_pages = ra->ra_pages; + unsigned long add_pages; pgoff_t prev_offset; /* @@ -470,10 +471,17 @@ readit: * Will this read hit the readahead marker made by itself? * If so, trigger the readahead marker hit now, and merge * the resulted next readahead window into the current one. + * Take care of maximum IO pages as above. */ if (offset == ra->start && ra->size == ra->async_size) { - ra->async_size = get_next_ra_size(ra, max_pages); - ra->size += ra->async_size; + add_pages = get_next_ra_size(ra, max_pages); + if (ra->size + add_pages <= max_pages) { + ra->async_size = add_pages; + ra->size += add_pages; + } else { + ra->size = max_pages; + ra->async_size = max_pages >> 1; + } } return ra_submit(ra, mapping, filp); |