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mm/readahead: add page_cache_sync_ra and page_cache_async_ra 

Reimplement page_cache_sync_readahead() and page_cache_async_readahead()
as wrappers around versions of the function which take a readahead_control
in preparation for making do_sync_mmap_readahead() pass down an RAC
struct.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Eric Biggers <ebiggers@google.com>
Link: https://lkml.kernel.org/r/20200903140844.14194-8-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2020-10-15 20:06:28 -07:00 committed by Linus Torvalds
parent 7b3df3b9ac
commit fefa7c478f
2 changed files with 66 additions and 56 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

64
include/linux/pagemap.h
View File

@ -761,16 +761,6 @@ int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask);
void delete_from_page_cache_batch(struct address_space *mapping,
struct pagevec *pvec);
#define VM_READAHEAD_PAGES (SZ_128K / PAGE_SIZE)
void page_cache_sync_readahead(struct address_space *, struct file_ra_state *,
struct file *, pgoff_t index, unsigned long req_count);
void page_cache_async_readahead(struct address_space *, struct file_ra_state *,
struct file *, struct page *, pgoff_t index,
unsigned long req_count);
void page_cache_ra_unbounded(struct readahead_control *,
unsigned long nr_to_read, unsigned long lookahead_count);
/*
* Like add_to_page_cache_locked, but used to add newly allocated pages:
* the page is new, so we can just run __SetPageLocked() against it.
@ -818,6 +808,60 @@ struct readahead_control {
._index = i, \
}
#define VM_READAHEAD_PAGES (SZ_128K / PAGE_SIZE)
void page_cache_ra_unbounded(struct readahead_control *,
unsigned long nr_to_read, unsigned long lookahead_count);
void page_cache_sync_ra(struct readahead_control *, struct file_ra_state *,
unsigned long req_count);
void page_cache_async_ra(struct readahead_control *, struct file_ra_state *,
struct page *, unsigned long req_count);
/**
* page_cache_sync_readahead - generic file readahead
* @mapping: address_space which holds the pagecache and I/O vectors
* @ra: file_ra_state which holds the readahead state
* @file: Used by the filesystem for authentication.
* @index: Index of first page to be read.
* @req_count: Total number of pages being read by the caller.
*
* page_cache_sync_readahead() should be called when a cache miss happened:
* it will submit the read. The readahead logic may decide to piggyback more
* pages onto the read request if access patterns suggest it will improve
* performance.
*/
static inline
void page_cache_sync_readahead(struct address_space *mapping,
struct file_ra_state *ra, struct file *file, pgoff_t index,
unsigned long req_count)
{
DEFINE_READAHEAD(ractl, file, mapping, index);
page_cache_sync_ra(&ractl, ra, req_count);
}
/**
* page_cache_async_readahead - file readahead for marked pages
* @mapping: address_space which holds the pagecache and I/O vectors
* @ra: file_ra_state which holds the readahead state
* @file: Used by the filesystem for authentication.
* @page: The page at @index which triggered the readahead call.
* @index: Index of first page to be read.
* @req_count: Total number of pages being read by the caller.
*
* page_cache_async_readahead() should be called when a page is used which
* is marked as PageReadahead; this is a marker to suggest that the application
* has used up enough of the readahead window that we should start pulling in
* more pages.
*/
static inline
void page_cache_async_readahead(struct address_space *mapping,
struct file_ra_state *ra, struct file *file,
struct page *page, pgoff_t index, unsigned long req_count)
{
DEFINE_READAHEAD(ractl, file, mapping, index);
page_cache_async_ra(&ractl, ra, page, req_count);
}
/**
* readahead_page - Get the next page to read.
* @rac: The current readahead request.

58
mm/readahead.c
View File

@ -550,25 +550,9 @@ readit:
do_page_cache_ra(ractl, ra->size, ra->async_size);
}
/**
* page_cache_sync_readahead - generic file readahead
* @mapping: address_space which holds the pagecache and I/O vectors
* @ra: file_ra_state which holds the readahead state
* @filp: passed on to ->readpage() and ->readpages()
* @index: Index of first page to be read.
* @req_count: Total number of pages being read by the caller.
*
* page_cache_sync_readahead() should be called when a cache miss happened:
* it will submit the read. The readahead logic may decide to piggyback more
* pages onto the read request if access patterns suggest it will improve
* performance.
*/
void page_cache_sync_readahead(struct address_space *mapping,
struct file_ra_state *ra, struct file *filp,
pgoff_t index, unsigned long req_count)
void page_cache_sync_ra(struct readahead_control *ractl,
struct file_ra_state *ra, unsigned long req_count)
{
DEFINE_READAHEAD(ractl, filp, mapping, index);
/* no read-ahead */
if (!ra->ra_pages)
return;
@ -577,38 +561,20 @@ void page_cache_sync_readahead(struct address_space *mapping,
return;
/* be dumb */
if (filp && (filp->f_mode & FMODE_RANDOM)) {
force_page_cache_ra(&ractl, req_count);
if (ractl->file && (ractl->file->f_mode & FMODE_RANDOM)) {
force_page_cache_ra(ractl, req_count);
return;
}
/* do read-ahead */
ondemand_readahead(&ractl, ra, false, req_count);
ondemand_readahead(ractl, ra, false, req_count);
}
EXPORT_SYMBOL_GPL(page_cache_sync_readahead);
EXPORT_SYMBOL_GPL(page_cache_sync_ra);
/**
* page_cache_async_readahead - file readahead for marked pages
* @mapping: address_space which holds the pagecache and I/O vectors
* @ra: file_ra_state which holds the readahead state
* @filp: passed on to ->readpage() and ->readpages()
* @page: The page at @index which triggered the readahead call.
* @index: Index of first page to be read.
* @req_count: Total number of pages being read by the caller.
*
* page_cache_async_readahead() should be called when a page is used which
* is marked as PageReadahead; this is a marker to suggest that the application
* has used up enough of the readahead window that we should start pulling in
* more pages.
*/
void
page_cache_async_readahead(struct address_space *mapping,
struct file_ra_state *ra, struct file *filp,
struct page *page, pgoff_t index,
unsigned long req_count)
void page_cache_async_ra(struct readahead_control *ractl,
struct file_ra_state *ra, struct page *page,
unsigned long req_count)
{
DEFINE_READAHEAD(ractl, filp, mapping, index);
/* no read-ahead */
if (!ra->ra_pages)
return;
@ -624,16 +590,16 @@ page_cache_async_readahead(struct address_space *mapping,
/*
* Defer asynchronous read-ahead on IO congestion.
*/
if (inode_read_congested(mapping->host))
if (inode_read_congested(ractl->mapping->host))
return;
if (blk_cgroup_congested())
return;
/* do read-ahead */
ondemand_readahead(&ractl, ra, true, req_count);
ondemand_readahead(ractl, ra, true, req_count);
}
EXPORT_SYMBOL_GPL(page_cache_async_readahead);
EXPORT_SYMBOL_GPL(page_cache_async_ra);
ssize_t ksys_readahead(int fd, loff_t offset, size_t count)
{