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readahead: fold try_context_readahead() into its single caller

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try_context_readahead() has a single caller page_cache_sync_ra().  Fold
the function there to make ra state modifications more obvious.  No
functional changes.

Link: https://lkml.kernel.org/r/20240625101909.12234-9-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Tested-by: Zhang Peng <zhangpengpeng0808@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Jan Kara 2024-06-25 12:18:59 +02:00 committed by Andrew Morton
parent 3a7a11a57e
commit a6eccd5be3
1 changed files with 22 additions and 62 deletions
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84
mm/readahead.c
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@ -410,58 +410,6 @@ static unsigned long get_next_ra_size(struct file_ra_state *ra,
* it approaches max_readhead.
*/
/*
* Count contiguously cached pages from @index-1 to @index-@max,
* this count is a conservative estimation of
* - length of the sequential read sequence, or
* - thrashing threshold in memory tight systems
*/
static pgoff_t count_history_pages(struct address_space *mapping,
pgoff_t index, unsigned long max)
{
pgoff_t head;
rcu_read_lock();
head = page_cache_prev_miss(mapping, index - 1, max);
rcu_read_unlock();
return index - 1 - head;
}
/*
* page cache context based readahead
*/
static int try_context_readahead(struct address_space *mapping,
struct file_ra_state *ra,
pgoff_t index,
unsigned long req_size,
unsigned long max)
{
pgoff_t size;
size = count_history_pages(mapping, index, max);
/*
* not enough history pages:
* it could be a random read
*/
if (size <= req_size)
return 0;
/*
* starts from beginning of file:
* it is a strong indication of long-run stream (or whole-file-read)
*/
if (size >= index)
size *= 2;
ra->start = index;
ra->size = min(size + req_size, max);
ra->async_size = 1;
return 1;
}
static inline int ra_alloc_folio(struct readahead_control *ractl, pgoff_t index,
pgoff_t mark, unsigned int order, gfp_t gfp)
{
@ -561,8 +509,8 @@ void page_cache_sync_ra(struct readahead_control *ractl,
pgoff_t index = readahead_index(ractl);
bool do_forced_ra = ractl->file && (ractl->file->f_mode & FMODE_RANDOM);
struct file_ra_state *ra = ractl->ra;
unsigned long max_pages;
pgoff_t prev_index;
unsigned long max_pages, contig_count;
pgoff_t prev_index, miss;
/*
* Even if readahead is disabled, issue this request as readahead
@ -603,16 +551,28 @@ void page_cache_sync_ra(struct readahead_control *ractl,
* Query the page cache and look for the traces(cached history pages)
* that a sequential stream would leave behind.
*/
if (try_context_readahead(ractl->mapping, ra, index, req_count,
max_pages))
goto readit;
rcu_read_lock();
miss = page_cache_prev_miss(ractl->mapping, index - 1, max_pages);
rcu_read_unlock();
contig_count = index - miss - 1;
/*
* standalone, small random read
* Read as is, and do not pollute the readahead state.
* Standalone, small random read. Read as is, and do not pollute the
* readahead state.
*/
do_page_cache_ra(ractl, req_count, 0);
return;
if (contig_count <= req_count) {
do_page_cache_ra(ractl, req_count, 0);
return;
}
/*
* File cached from the beginning:
* it is a strong indication of long-run stream (or whole-file-read)
*/
if (miss == ULONG_MAX)
contig_count *= 2;
ra->start = index;
ra->size = min(contig_count + req_count, max_pages);
ra->async_size = 1;
goto readit;
initial_readahead:
ra->start = index;