From: Luis Chamberlain <mcgrof@xxxxxxxxxx>
Align the ra->start and ra->size to mapping_min_order in
ondemand_readahead(), and align the index to mapping_min_order in
force_page_cache_ra(). This will ensure that the folios allocated for
readahead that are added to the page cache are aligned to
mapping_min_order.
Signed-off-by: Luis Chamberlain <mcgrof@xxxxxxxxxx>
Signed-off-by: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
---
mm/readahead.c | 27 ++++++++++++++++++++-------
1 file changed, 20 insertions(+), 7 deletions(-)
diff --git a/mm/readahead.c b/mm/readahead.c
index 8a610b78d94b..325a25e4ee3a 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -313,7 +313,9 @@ void force_page_cache_ra(struct readahead_control *ractl,
struct address_space *mapping = ractl->mapping;
struct file_ra_state *ra = ractl->ra;
struct backing_dev_info *bdi = inode_to_bdi(mapping->host);
- unsigned long max_pages, index;
+ unsigned long max_pages;
+ pgoff_t index, new_index;
+ unsigned long min_nrpages = mapping_min_folio_nrpages(mapping);
if (unlikely(!mapping->a_ops->read_folio && !mapping->a_ops->readahead))
return;
@@ -323,7 +325,14 @@ void force_page_cache_ra(struct readahead_control *ractl,
* be up to the optimal hardware IO size
*/
index = readahead_index(ractl);
+ new_index = mapping_align_start_index(mapping, index);
+ if (new_index != index) {
+ nr_to_read += index - new_index;
+ index = new_index;
+ }
+
max_pages = max_t(unsigned long, bdi->io_pages, ra->ra_pages);
+ max_pages = max_t(unsigned long, max_pages, min_nrpages);
nr_to_read = min_t(unsigned long, nr_to_read, max_pages);
while (nr_to_read) {
unsigned long this_chunk = (2 * 1024 * 1024) / PAGE_SIZE;
@@ -331,6 +340,7 @@ void force_page_cache_ra(struct readahead_control *ractl,
if (this_chunk > nr_to_read)
this_chunk = nr_to_read;
ractl->_index = index;
+ VM_BUG_ON(!IS_ALIGNED(index, min_nrpages));
do_page_cache_ra(ractl, this_chunk, 0);
index += this_chunk;
@@ -557,8 +567,11 @@ static void ondemand_readahead(struct readahead_control *ractl,
unsigned long add_pages;
pgoff_t index = readahead_index(ractl);
pgoff_t expected, prev_index;
- unsigned int order = folio ? folio_order(folio) : 0;
+ unsigned int min_order = mapping_min_folio_order(ractl->mapping);
+ unsigned int min_nrpages = mapping_min_folio_nrpages(ractl->mapping);
+ unsigned int order = folio ? folio_order(folio) : min_order;
+ VM_BUG_ON(!IS_ALIGNED(index, min_nrpages));
/*
* If the request exceeds the readahead window, allow the read to
* be up to the optimal hardware IO size
@@ -580,7 +593,7 @@ static void ondemand_readahead(struct readahead_control *ractl,
1UL << order);
if (index == expected || index == (ra->start + ra->size)) {
ra->start += ra->size;
- ra->size = get_next_ra_size(ra, max_pages);
+ ra->size = max(get_next_ra_size(ra, max_pages), min_nrpages);
ra->async_size = ra->size;
goto readit;
}
@@ -605,7 +618,7 @@ static void ondemand_readahead(struct readahead_control *ractl,
ra->start = start;
ra->size = start - index; /* old async_size */
ra->size += req_size;
- ra->size = get_next_ra_size(ra, max_pages);
+ ra->size = max(get_next_ra_size(ra, max_pages), min_nrpages);
ra->async_size = ra->size;
goto readit;
}
@@ -642,7 +655,7 @@ static void ondemand_readahead(struct readahead_control *ractl,
initial_readahead:
ra->start = index;
- ra->size = get_init_ra_size(req_size, max_pages);
+ ra->size = max(min_nrpages, get_init_ra_size(req_size, max_pages));
ra->async_size = ra->size > req_size ? ra->size - req_size : ra->size;
readit:
@@ -653,7 +666,7 @@ static void ondemand_readahead(struct readahead_control *ractl,
* Take care of maximum IO pages as above.
*/
if (index == ra->start && ra->size == ra->async_size) {
- add_pages = get_next_ra_size(ra, max_pages);
+ add_pages = max(get_next_ra_size(ra, max_pages), min_nrpages);
if (ra->size + add_pages <= max_pages) {
ra->async_size = add_pages;
ra->size += add_pages;
@@ -663,7 +676,7 @@ static void ondemand_readahead(struct readahead_control *ractl,
}
}
- ractl->_index = ra->start;
+ ractl->_index = mapping_align_start_index(ractl->mapping, ra->start);
page_cache_ra_order(ractl, ra, order);
}
--
2.43.0
