}
/**
- * page_cache_readahead_unbounded - Start unchecked readahead.
- * @mapping: File address space.
- * @file: This instance of the open file; used for authentication.
- * @index: First page index to read.
+ * page_cache_ra_unbounded - Start unchecked readahead.
+ * @ractl: Readahead control.
* @nr_to_read: The number of pages to read.
* @lookahead_size: Where to start the next readahead.
*
* Context: File is referenced by caller. Mutexes may be held by caller.
* May sleep, but will not reenter filesystem to reclaim memory.
*/
-void page_cache_readahead_unbounded(struct address_space *mapping,
- struct file *file, pgoff_t index, unsigned long nr_to_read,
- unsigned long lookahead_size)
+void page_cache_ra_unbounded(struct readahead_control *ractl,
+ unsigned long nr_to_read, unsigned long lookahead_size)
{
+ struct address_space *mapping = ractl->mapping;
+ unsigned long index = readahead_index(ractl);
LIST_HEAD(page_pool);
gfp_t gfp_mask = readahead_gfp_mask(mapping);
- struct readahead_control rac = {
- .mapping = mapping,
- .file = file,
- ._index = index,
- };
unsigned long i;
/*
for (i = 0; i < nr_to_read; i++) {
struct page *page = xa_load(&mapping->i_pages, index + i);
- BUG_ON(index + i != rac._index + rac._nr_pages);
+ BUG_ON(index + i != ractl->_index + ractl->_nr_pages);
if (page && !xa_is_value(page)) {
/*
* have a stable reference to this page, and it's
* not worth getting one just for that.
*/
- read_pages(&rac, &page_pool, true);
+ read_pages(ractl, &page_pool, true);
continue;
}
} else if (add_to_page_cache_lru(page, mapping, index + i,
gfp_mask) < 0) {
put_page(page);
- read_pages(&rac, &page_pool, true);
+ read_pages(ractl, &page_pool, true);
continue;
}
if (i == nr_to_read - lookahead_size)
SetPageReadahead(page);
- rac._nr_pages++;
+ ractl->_nr_pages++;
}
/*
* uptodate then the caller will launch readpage again, and
* will then handle the error.
*/
- read_pages(&rac, &page_pool, false);
+ read_pages(ractl, &page_pool, false);
memalloc_nofs_restore(nofs);
}
-EXPORT_SYMBOL_GPL(page_cache_readahead_unbounded);
+EXPORT_SYMBOL_GPL(page_cache_ra_unbounded);
/*
- * __do_page_cache_readahead() actually reads a chunk of disk. It allocates
+ * do_page_cache_ra() actually reads a chunk of disk. It allocates
* the pages first, then submits them for I/O. This avoids the very bad
* 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_ra(struct readahead_control *ractl,
+ unsigned long nr_to_read, unsigned long lookahead_size)
{
- struct inode *inode = mapping->host;
+ struct inode *inode = ractl->mapping->host;
+ unsigned long index = readahead_index(ractl);
loff_t isize = i_size_read(inode);
pgoff_t end_index; /* The last page we want to read */
if (nr_to_read > end_index - index)
nr_to_read = end_index - index + 1;
- page_cache_readahead_unbounded(mapping, file, index, nr_to_read,
- lookahead_size);
+ page_cache_ra_unbounded(ractl, nr_to_read, lookahead_size);
}
/*
* Chunk the readahead into 2 megabyte units, so that we don't pin too much
* memory at once.
*/
-void force_page_cache_readahead(struct address_space *mapping,
- struct file *filp, pgoff_t index, unsigned long nr_to_read)
+void force_page_cache_ra(struct readahead_control *ractl,
+ struct file_ra_state *ra, unsigned long nr_to_read)
{
+ struct address_space *mapping = ractl->mapping;
struct backing_dev_info *bdi = inode_to_bdi(mapping->host);
- struct file_ra_state *ra = &filp->f_ra;
- unsigned long max_pages;
+ unsigned long max_pages, index;
if (unlikely(!mapping->a_ops->readpage && !mapping->a_ops->readpages &&
!mapping->a_ops->readahead))
* If the request exceeds the readahead window, allow the read to
* be up to the optimal hardware IO size
*/
+ index = readahead_index(ractl);
max_pages = max_t(unsigned long, bdi->io_pages, ra->ra_pages);
- nr_to_read = min(nr_to_read, max_pages);
+ 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;
if (this_chunk > nr_to_read)
this_chunk = nr_to_read;
- __do_page_cache_readahead(mapping, filp, index, this_chunk, 0);
+ ractl->_index = index;
+ do_page_cache_ra(ractl, this_chunk, 0);
index += this_chunk;
nr_to_read -= this_chunk;
/*
* 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,
- bool hit_readahead_marker, pgoff_t index,
+static void ondemand_readahead(struct readahead_control *ractl,
+ struct file_ra_state *ra, bool hit_readahead_marker,
unsigned long req_size)
{
- struct backing_dev_info *bdi = inode_to_bdi(mapping->host);
+ struct backing_dev_info *bdi = inode_to_bdi(ractl->mapping->host);
unsigned long max_pages = ra->ra_pages;
unsigned long add_pages;
+ unsigned long index = readahead_index(ractl);
pgoff_t prev_index;
/*
pgoff_t start;
rcu_read_lock();
- start = page_cache_next_miss(mapping, index + 1, max_pages);
+ start = page_cache_next_miss(ractl->mapping, index + 1,
+ max_pages);
rcu_read_unlock();
if (!start || start - index > max_pages)
* Query the page cache and look for the traces(cached history pages)
* that a sequential stream would leave behind.
*/
- if (try_context_readahead(mapping, ra, index, req_size, max_pages))
+ if (try_context_readahead(ractl->mapping, ra, index, req_size,
+ max_pages))
goto readit;
/*
* 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_ra(ractl, req_size, 0);
return;
initial_readahead:
}
}
- ra_submit(ra, mapping, filp);
+ ractl->_index = ra->start;
+ 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)
{
- /* no read-ahead */
- if (!ra->ra_pages)
- return;
+ bool do_forced_ra = ractl->file && (ractl->file->f_mode & FMODE_RANDOM);
- if (blk_cgroup_congested())
- return;
+ /*
+ * Even if read-ahead is disabled, issue this request as read-ahead
+ * as we'll need it to satisfy the requested range. The forced
+ * read-ahead will do the right thing and limit the read to just the
+ * requested range, which we'll set to 1 page for this case.
+ */
+ if (!ra->ra_pages || blk_cgroup_congested()) {
+ if (!ractl->file)
+ return;
+ req_count = 1;
+ do_forced_ra = true;
+ }
/* be dumb */
- if (filp && (filp->f_mode & FMODE_RANDOM)) {
- force_page_cache_readahead(mapping, filp, index, req_count);
+ if (do_forced_ra) {
+ force_page_cache_ra(ractl, ra, req_count);
return;
}
/* do read-ahead */
- ondemand_readahead(mapping, ra, filp, false, index, 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)
{
/* no read-ahead */
if (!ra->ra_pages)
/*
* 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(mapping, ra, filp, true, index, 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)
{
projects / linux-2.6-microblaze.git / blobdiff