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authorLinus Torvalds <torvalds@g5.osdl.org>2006-04-27 14:24:20 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-04-27 14:24:20 -0700
commit7c1c3eb855b5311118bed3b51c79d652d40148ec (patch)
treec1964e8d08318ccaaba8882d5eb38778311d7ead
parent6e5882cfa24e1456702e463f6920fc0ca3c3d2b8 (diff)
parenteb20796bf6fdb95ccf51440ba2a827149bdc037f (diff)
Merge branch 'splice' of git://brick.kernel.dk/data/git/linux-2.6-block
* 'splice' of git://brick.kernel.dk/data/git/linux-2.6-block: [PATCH] splice: make the read-side do batched page lookups [PATCH] Add find_get_pages_contig(): contiguous variant of find_get_pages() [PATCH] splice: switch to using page_cache_readahead()
-rw-r--r--fs/splice.c99
-rw-r--r--include/linux/pagemap.h2
-rw-r--r--mm/filemap.c32
3 files changed, 101 insertions, 32 deletions
diff --git a/fs/splice.c b/fs/splice.c
index 447ebc0a37f..a46ddd28561 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -279,7 +279,7 @@ __generic_file_splice_read(struct file *in, loff_t *ppos,
pgoff_t index, end_index;
loff_t isize;
size_t total_len;
- int error;
+ int error, page_nr;
struct splice_pipe_desc spd = {
.pages = pages,
.partial = partial,
@@ -299,47 +299,75 @@ __generic_file_splice_read(struct file *in, loff_t *ppos,
* read-ahead if this is a non-zero offset (we are likely doing small
* chunk splice and the page is already there) for a single page.
*/
- if (!loff || spd.nr_pages > 1)
- do_page_cache_readahead(mapping, in, index, spd.nr_pages);
+ if (!loff || nr_pages > 1)
+ page_cache_readahead(mapping, &in->f_ra, in, index, nr_pages);
/*
* Now fill in the holes:
*/
error = 0;
total_len = 0;
- for (spd.nr_pages = 0; spd.nr_pages < nr_pages; spd.nr_pages++, index++) {
- unsigned int this_len;
- if (!len)
- break;
+ /*
+ * Lookup the (hopefully) full range of pages we need.
+ */
+ spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, pages);
+ /*
+ * If find_get_pages_contig() returned fewer pages than we needed,
+ * allocate the rest.
+ */
+ index += spd.nr_pages;
+ while (spd.nr_pages < nr_pages) {
/*
- * this_len is the max we'll use from this page
- */
- this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff);
-find_page:
- /*
- * lookup the page for this index
+ * Page could be there, find_get_pages_contig() breaks on
+ * the first hole.
*/
page = find_get_page(mapping, index);
if (!page) {
/*
- * page didn't exist, allocate one
+ * page didn't exist, allocate one.
*/
page = page_cache_alloc_cold(mapping);
if (!page)
break;
error = add_to_page_cache_lru(page, mapping, index,
- mapping_gfp_mask(mapping));
+ mapping_gfp_mask(mapping));
if (unlikely(error)) {
page_cache_release(page);
break;
}
-
- goto readpage;
+ /*
+ * add_to_page_cache() locks the page, unlock it
+ * to avoid convoluting the logic below even more.
+ */
+ unlock_page(page);
}
+ pages[spd.nr_pages++] = page;
+ index++;
+ }
+
+ /*
+ * Now loop over the map and see if we need to start IO on any
+ * pages, fill in the partial map, etc.
+ */
+ index = *ppos >> PAGE_CACHE_SHIFT;
+ nr_pages = spd.nr_pages;
+ spd.nr_pages = 0;
+ for (page_nr = 0; page_nr < nr_pages; page_nr++) {
+ unsigned int this_len;
+
+ if (!len)
+ break;
+
+ /*
+ * this_len is the max we'll use from this page
+ */
+ this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff);
+ page = pages[page_nr];
+
/*
* If the page isn't uptodate, we may need to start io on it
*/
@@ -360,7 +388,6 @@ find_page:
*/
if (!page->mapping) {
unlock_page(page);
- page_cache_release(page);
break;
}
/*
@@ -371,16 +398,20 @@ find_page:
goto fill_it;
}
-readpage:
/*
* need to read in the page
*/
error = mapping->a_ops->readpage(in, page);
-
if (unlikely(error)) {
- page_cache_release(page);
+ /*
+ * We really should re-lookup the page here,
+ * but it complicates things a lot. Instead
+ * lets just do what we already stored, and
+ * we'll get it the next time we are called.
+ */
if (error == AOP_TRUNCATED_PAGE)
- goto find_page;
+ error = 0;
+
break;
}
@@ -389,10 +420,8 @@ readpage:
*/
isize = i_size_read(mapping->host);
end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
- if (unlikely(!isize || index > end_index)) {
- page_cache_release(page);
+ if (unlikely(!isize || index > end_index))
break;
- }
/*
* if this is the last page, see if we need to shrink
@@ -400,27 +429,33 @@ readpage:
*/
if (end_index == index) {
loff = PAGE_CACHE_SIZE - (isize & ~PAGE_CACHE_MASK);
- if (total_len + loff > isize) {
- page_cache_release(page);
+ if (total_len + loff > isize)
break;
- }
/*
* force quit after adding this page
*/
- nr_pages = spd.nr_pages;
+ len = this_len;
this_len = min(this_len, loff);
loff = 0;
}
}
fill_it:
- pages[spd.nr_pages] = page;
- partial[spd.nr_pages].offset = loff;
- partial[spd.nr_pages].len = this_len;
+ partial[page_nr].offset = loff;
+ partial[page_nr].len = this_len;
len -= this_len;
total_len += this_len;
loff = 0;
+ spd.nr_pages++;
+ index++;
}
+ /*
+ * Release any pages at the end, if we quit early. 'i' is how far
+ * we got, 'nr_pages' is how many pages are in the map.
+ */
+ while (page_nr < nr_pages)
+ page_cache_release(pages[page_nr++]);
+
if (spd.nr_pages)
return splice_to_pipe(pipe, &spd);
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 9539efd4f7e..7a1af574ded 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -78,6 +78,8 @@ extern struct page * find_or_create_page(struct address_space *mapping,
unsigned long index, gfp_t gfp_mask);
unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
unsigned int nr_pages, struct page **pages);
+unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start,
+ unsigned int nr_pages, struct page **pages);
unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
int tag, unsigned int nr_pages, struct page **pages);
diff --git a/mm/filemap.c b/mm/filemap.c
index 3ef20739e72..fd57442186c 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -697,6 +697,38 @@ unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
return ret;
}
+/**
+ * find_get_pages_contig - gang contiguous pagecache lookup
+ * @mapping: The address_space to search
+ * @index: The starting page index
+ * @nr_pages: The maximum number of pages
+ * @pages: Where the resulting pages are placed
+ *
+ * find_get_pages_contig() works exactly like find_get_pages(), except
+ * that the returned number of pages are guaranteed to be contiguous.
+ *
+ * find_get_pages_contig() returns the number of pages which were found.
+ */
+unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
+ unsigned int nr_pages, struct page **pages)
+{
+ unsigned int i;
+ unsigned int ret;
+
+ read_lock_irq(&mapping->tree_lock);
+ ret = radix_tree_gang_lookup(&mapping->page_tree,
+ (void **)pages, index, nr_pages);
+ for (i = 0; i < ret; i++) {
+ if (pages[i]->mapping == NULL || pages[i]->index != index)
+ break;
+
+ page_cache_get(pages[i]);
+ index++;
+ }
+ read_unlock_irq(&mapping->tree_lock);
+ return i;
+}
+
/*
* Like find_get_pages, except we only return pages which are tagged with
* `tag'. We update *index to index the next page for the traversal.