*/
#include <linux/kernel.h>
-#include <linux/fs.h>
#include <linux/gfp.h>
-#include <linux/mm.h>
#include <linux/export.h>
#include <linux/blkdev.h>
#include <linux/backing-dev.h>
#include <linux/syscalls.h>
#include <linux/file.h>
+#include "internal.h"
+
/*
* Initialise a struct file's readahead state. Assumes that the caller has
* memset *ra to zero.
*
* Returns the number of pages requested, or the maximum amount of I/O allowed.
*/
-static int
-__do_page_cache_readahead(struct address_space *mapping, struct file *filp,
+int __do_page_cache_readahead(struct address_space *mapping, struct file *filp,
pgoff_t offset, unsigned long nr_to_read,
unsigned long lookahead_size)
{
rcu_read_lock();
page = radix_tree_lookup(&mapping->page_tree, page_offset);
rcu_read_unlock();
- if (page)
+ if (page && !radix_tree_exceptional_entry(page))
continue;
page = page_cache_alloc_readahead(mapping);
int force_page_cache_readahead(struct address_space *mapping, struct file *filp,
pgoff_t offset, unsigned long nr_to_read)
{
- int ret = 0;
-
if (unlikely(!mapping->a_ops->readpage && !mapping->a_ops->readpages))
return -EINVAL;
this_chunk = nr_to_read;
err = __do_page_cache_readahead(mapping, filp,
offset, this_chunk, 0);
- if (err < 0) {
- ret = err;
- break;
- }
- ret += err;
+ if (err < 0)
+ return err;
+
offset += this_chunk;
nr_to_read -= this_chunk;
}
- return ret;
+ return 0;
}
+#define MAX_READAHEAD ((512*4096)/PAGE_CACHE_SIZE)
/*
* Given a desired number of PAGE_CACHE_SIZE readahead pages, return a
* sensible upper limit.
*/
unsigned long max_sane_readahead(unsigned long nr)
{
- return min(nr, (node_page_state(numa_node_id(), NR_INACTIVE_FILE)
- + node_page_state(numa_node_id(), NR_FREE_PAGES)) / 2);
-}
-
-/*
- * Submit IO for the read-ahead request in file_ra_state.
- */
-unsigned long ra_submit(struct file_ra_state *ra,
- struct address_space *mapping, struct file *filp)
-{
- int actual;
-
- actual = __do_page_cache_readahead(mapping, filp,
- ra->start, ra->size, ra->async_size);
-
- return actual;
+ return min(nr, MAX_READAHEAD);
}
/*
pgoff_t head;
rcu_read_lock();
- head = radix_tree_prev_hole(&mapping->page_tree, offset - 1, max);
+ head = page_cache_prev_hole(mapping, offset - 1, max);
rcu_read_unlock();
return offset - 1 - head;
pgoff_t start;
rcu_read_lock();
- start = radix_tree_next_hole(&mapping->page_tree, offset+1,max);
+ start = page_cache_next_hole(mapping, offset + 1, max);
rcu_read_unlock();
if (!start || start - offset > max)
if (!mapping || !mapping->a_ops)
return -EINVAL;
- force_page_cache_readahead(mapping, filp, index, nr);
- return 0;
+ return force_page_cache_readahead(mapping, filp, index, nr);
}
SYSCALL_DEFINE3(readahead, int, fd, loff_t, offset, size_t, count)