#include <linux/blkdev.h>
#include <linux/backing-dev.h>
#include <linux/pagevec.h>
+#include <linux/buffer_head.h>
void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
{
return (VM_MIN_READAHEAD * 1024) / PAGE_CACHE_SIZE;
}
+static inline void reset_ahead_window(struct file_ra_state *ra)
+{
+ /*
+ * ... but preserve ahead_start + ahead_size value,
+ * see 'recheck:' label in page_cache_readahead().
+ * Note: We never use ->ahead_size as rvalue without
+ * checking ->ahead_start != 0 first.
+ */
+ ra->ahead_size += ra->ahead_start;
+ ra->ahead_start = 0;
+}
+
static inline void ra_off(struct file_ra_state *ra)
{
ra->start = 0;
ra->flags = 0;
ra->size = 0;
- ra->ahead_start = 0;
- ra->ahead_size = 0;
+ reset_ahead_window(ra);
return;
}
{
unsigned long newsize = roundup_pow_of_two(size);
- if (newsize <= max / 64)
- newsize = newsize * newsize;
+ if (newsize <= max / 32)
+ newsize = newsize * 4;
else if (newsize <= max / 4)
- newsize = max / 4;
+ newsize = newsize * 2;
else
newsize = max;
return newsize;
#define list_to_page(head) (list_entry((head)->prev, struct page, lru))
+/*
+ * see if a page needs releasing upon read_cache_pages() failure
+ * - the caller of read_cache_pages() may have set PG_private before calling,
+ * such as the NFS fs marking pages that are cached locally on disk, thus we
+ * need to give the fs a chance to clean up in the event of an error
+ */
+static void read_cache_pages_release_page(struct address_space *mapping,
+ struct page *page)
+{
+ if (PagePrivate(page)) {
+ if (TestSetPageLocked(page))
+ BUG();
+ page->mapping = mapping;
+ try_to_release_page(page, GFP_KERNEL);
+ page->mapping = NULL;
+ unlock_page(page);
+ }
+ page_cache_release(page);
+}
+
/**
- * read_cache_pages - populate an address space with some pages, and
- * start reads against them.
+ * read_cache_pages - populate an address space with some pages & start reads against them
* @mapping: the address_space
* @pages: The address of a list_head which contains the target pages. These
* pages have their ->index populated and are otherwise uninitialised.
page = list_to_page(pages);
list_del(&page->lru);
if (add_to_page_cache(page, mapping, page->index, GFP_KERNEL)) {
- page_cache_release(page);
+ read_cache_pages_release_page(mapping, page);
continue;
}
ret = filler(data, page);
victim = list_to_page(pages);
list_del(&victim->lru);
- page_cache_release(victim);
+ read_cache_pages_release_page(mapping, victim);
}
break;
}
{
unsigned page_idx;
struct pagevec lru_pvec;
- int ret = 0;
+ int ret;
if (mapping->a_ops->readpages) {
ret = mapping->a_ops->readpages(filp, mapping, pages, nr_pages);
mapping->a_ops->readpage(filp, page);
if (!pagevec_add(&lru_pvec, page))
__pagevec_lru_add(&lru_pvec);
- } else {
+ } else
page_cache_release(page);
- }
}
pagevec_lru_add(&lru_pvec);
+ ret = 0;
out:
return ret;
}
*/
static int
__do_page_cache_readahead(struct address_space *mapping, struct file *filp,
- unsigned long offset, unsigned long nr_to_read)
+ pgoff_t offset, unsigned long nr_to_read)
{
struct inode *inode = mapping->host;
struct page *page;
*/
read_lock_irq(&mapping->tree_lock);
for (page_idx = 0; page_idx < nr_to_read; page_idx++) {
- unsigned long page_offset = offset + page_idx;
+ pgoff_t page_offset = offset + page_idx;
if (page_offset > end_index)
break;
* memory at once.
*/
int force_page_cache_readahead(struct address_space *mapping, struct file *filp,
- unsigned long offset, unsigned long nr_to_read)
+ pgoff_t offset, unsigned long nr_to_read)
{
int ret = 0;
* request queues.
*/
int do_page_cache_readahead(struct address_space *mapping, struct file *filp,
- unsigned long offset, unsigned long nr_to_read)
+ pgoff_t offset, unsigned long nr_to_read)
{
if (bdi_read_congested(mapping->backing_dev_info))
return -1;
* Read 'nr_to_read' pages starting at page 'offset'. If the flag 'block'
* is set wait till the read completes. Otherwise attempt to read without
* blocking.
- * Returns 1 meaning 'success' if read is succesfull without switching off
- * readhaead mode. Otherwise return failure.
+ * Returns 1 meaning 'success' if read is successful without switching off
+ * readahead mode. Otherwise return failure.
*/
static int
blockable_page_cache_readahead(struct address_space *mapping, struct file *filp,
- unsigned long offset, unsigned long nr_to_read,
+ pgoff_t offset, unsigned long nr_to_read,
struct file_ra_state *ra, int block)
{
int actual;
* congestion. The ahead window will any way be closed
* in case we failed due to excessive page cache hits.
*/
- ra->ahead_start = 0;
- ra->ahead_size = 0;
+ reset_ahead_window(ra);
}
return ret;
}
-/*
- * page_cache_readahead is the main function. If performs the adaptive
+/**
+ * page_cache_readahead - generic adaptive 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()
+ * @offset: start offset into @mapping, in PAGE_CACHE_SIZE units
+ * @req_size: hint: total size of the read which the caller is performing in
+ * PAGE_CACHE_SIZE units
+ *
+ * page_cache_readahead() is the main function. If performs the adaptive
* readahead window size management and submits the readahead I/O.
+ *
+ * Note that @filp is purely used for passing on to the ->readpage[s]()
+ * handler: it may refer to a different file from @mapping (so we may not use
+ * @filp->f_mapping or @filp->f_dentry->d_inode here).
+ * Also, @ra may not be equal to &@filp->f_ra.
+ *
*/
unsigned long
page_cache_readahead(struct address_space *mapping, struct file_ra_state *ra,
- struct file *filp, unsigned long offset,
- unsigned long req_size)
+ struct file *filp, pgoff_t offset, unsigned long req_size)
{
unsigned long max, newsize;
int sequential;
* If we get here we are doing sequential IO and this was not the first
* occurence (ie we have an existing window)
*/
-
if (ra->ahead_start == 0) { /* no ahead window yet */
if (!make_ahead_window(mapping, filp, ra, 0))
- goto out;
+ goto recheck;
}
+
/*
* Already have an ahead window, check if we crossed into it.
* If so, shift windows and issue a new ahead window.
ra->start = ra->ahead_start;
ra->size = ra->ahead_size;
make_ahead_window(mapping, filp, ra, 0);
+recheck:
+ /* prev_page shouldn't overrun the ahead window */
+ ra->prev_page = min(ra->prev_page,
+ ra->ahead_start + ra->ahead_size - 1);
}
out:
return ra->prev_page + 1;
}
+EXPORT_SYMBOL_GPL(page_cache_readahead);
/*
* handle_ra_miss() is called when it is known that a page which should have
{
ra->flags |= RA_FLAG_MISS;
ra->flags &= ~RA_FLAG_INCACHE;
+ ra->cache_hit = 0;
}
/*
git://git.onelab.eu / linux-2.6.git / blobdiff