[PATCH v4 33/36] mm: Make __do_page_cache_readahead take a readahead_control

Matthew Wilcox
2020-05-15T13:40:37Z

Also call __do_page_cache_readahead() directly from ondemand_readahead()
instead of indirecting via ra_submit().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
mm/internal.h | 11 +++++------
mm/readahead.c | 26 ++++++++++++++------------
2 files changed, 19 insertions(+), 18 deletions(-)

diff --git a/mm/internal.h b/mm/internal.h
index 5efb13d5c226..fd3eaff7acdc 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -51,18 +51,17 @@ void unmap_page_range(struct mmu_gather *tlb,

void force_page_cache_readahead(struct address_space *, struct file *,
pgoff_t index, unsigned long nr_to_read);
-void __do_page_cache_readahead(struct address_space *, struct file *,
- pgoff_t index, unsigned long nr_to_read,
- unsigned long lookahead_size);
+void __do_page_cache_readahead(struct readahead_control *,
+ unsigned long nr_to_read, unsigned long lookahead_size);

/*
* Submit IO for the read-ahead request in file_ra_state.
*/
static inline void ra_submit(struct file_ra_state *ra,
- struct address_space *mapping, struct file *filp)
+ struct address_space *mapping, struct file *file)
{
- __do_page_cache_readahead(mapping, filp,
- ra->start, ra->size, ra->async_size);
+ DEFINE_READAHEAD(rac, file, mapping, ra->start);
+ __do_page_cache_readahead(&rac, ra->size, ra->async_size);
}

/**
diff --git a/mm/readahead.c b/mm/readahead.c
index 62da2d4beed1..74c7e1eff540 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -246,12 +246,11 @@ EXPORT_SYMBOL_GPL(page_cache_readahead_unbounded);
* behaviour which would occur if page allocations are causing VM writeback.
* We really don't want to intermingle reads and writes like that.
*/
-void __do_page_cache_readahead(struct address_space *mapping,
- struct file *file, pgoff_t index, unsigned long nr_to_read,
- unsigned long lookahead_size)
+void __do_page_cache_readahead(struct readahead_control *rac,
+ unsigned long nr_to_read, unsigned long lookahead_size)
{
- DEFINE_READAHEAD(rac, file, mapping, index);
- struct inode *inode = mapping->host;
+ struct inode *inode = rac->mapping->host;
+ unsigned long index = readahead_index(rac);
loff_t isize = i_size_read(inode);
pgoff_t end_index; /* The last page we want to read */

@@ -265,7 +264,7 @@ void __do_page_cache_readahead(struct address_space *mapping,
if (nr_to_read > end_index - index)
nr_to_read = end_index - index + 1;

- page_cache_readahead_unbounded(&rac, nr_to_read, lookahead_size);
+ page_cache_readahead_unbounded(rac, nr_to_read, lookahead_size);
}

/*
@@ -273,10 +272,11 @@ void __do_page_cache_readahead(struct address_space *mapping,
* memory at once.
*/
void force_page_cache_readahead(struct address_space *mapping,
- struct file *filp, pgoff_t index, unsigned long nr_to_read)
+ struct file *file, pgoff_t index, unsigned long nr_to_read)
{
+ DEFINE_READAHEAD(rac, file, mapping, index);
struct backing_dev_info *bdi = inode_to_bdi(mapping->host);
- struct file_ra_state *ra = &filp->f_ra;
+ struct file_ra_state *ra = &file->f_ra;
unsigned long max_pages;

if (unlikely(!mapping->a_ops->readpage && !mapping->a_ops->readpages &&
@@ -294,7 +294,7 @@ void force_page_cache_readahead(struct address_space *mapping,

if (this_chunk > nr_to_read)
this_chunk = nr_to_read;
- __do_page_cache_readahead(mapping, filp, index, this_chunk, 0);
+ __do_page_cache_readahead(&rac, this_chunk, 0);

index += this_chunk;
nr_to_read -= this_chunk;
@@ -432,10 +432,11 @@ static int try_context_readahead(struct address_space *mapping,
* A minimal readahead algorithm for trivial sequential/random reads.
*/
static void ondemand_readahead(struct address_space *mapping,
- struct file_ra_state *ra, struct file *filp,
+ struct file_ra_state *ra, struct file *file,
bool hit_readahead_marker, pgoff_t index,
unsigned long req_size)
{
+ DEFINE_READAHEAD(rac, file, mapping, index);
struct backing_dev_info *bdi = inode_to_bdi(mapping->host);
unsigned long max_pages = ra->ra_pages;
unsigned long add_pages;
@@ -516,7 +517,7 @@ static void ondemand_readahead(struct address_space *mapping,
* standalone, small random read
* Read as is, and do not pollute the readahead state.
*/
- __do_page_cache_readahead(mapping, filp, index, req_size, 0);
+ __do_page_cache_readahead(&rac, req_size, 0);
return;

initial_readahead:
@@ -542,7 +543,8 @@ static void ondemand_readahead(struct address_space *mapping,
}
}

- ra_submit(ra, mapping, filp);
+ rac._index = ra->start;
+ __do_page_cache_readahead(&rac, ra->size, ra->async_size);
}

/**
--
2.26.2