The patch titled
Subject: mm: add page_cache_readahead_unbounded
has been added to the -mm tree. Its filename is
mm-add-page_cache_readahead_unbounded.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-add-page_cache_readahead_unbounded.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-add-page_cache_readahead_unbounded.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
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------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Subject: mm: add page_cache_readahead_unbounded
ext4 and f2fs have duplicated the guts of the readahead code so they can
read past i_size. Instead, separate out the guts of the readahead code so
they can call it directly.
Link: http://lkml.kernel.org/r/20200414150233.24495-14-willy@xxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: William Kucharski <william.kucharski@xxxxxxxxxx>
Reviewed-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Tested-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Cc: Chao Yu <yuchao0@xxxxxxxxxx>
Cc: Cong Wang <xiyou.wangcong@xxxxxxxxx>
Cc: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Cc: Dave Chinner <dchinner@xxxxxxxxxx>
Cc: Gao Xiang <gaoxiang25@xxxxxxxxxx>
Cc: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx>
Cc: Junxiao Bi <junxiao.bi@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Zi Yan <ziy@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/ext4/verity.c | 35 +------------------
fs/f2fs/data.c | 2 -
fs/f2fs/f2fs.h | 3 -
fs/f2fs/verity.c | 35 +------------------
include/linux/pagemap.h | 3 +
mm/readahead.c | 68 ++++++++++++++++++++++++++------------
6 files changed, 55 insertions(+), 91 deletions(-)
--- a/fs/ext4/verity.c~mm-add-page_cache_readahead_unbounded
+++ a/fs/ext4/verity.c
@@ -342,37 +342,6 @@ static int ext4_get_verity_descriptor(st
return desc_size;
}
-/*
- * Prefetch some pages from the file's Merkle tree.
- *
- * This is basically a stripped-down version of __do_page_cache_readahead()
- * which works on pages past i_size.
- */
-static void ext4_merkle_tree_readahead(struct address_space *mapping,
- pgoff_t start_index, unsigned long count)
-{
- LIST_HEAD(pages);
- unsigned int nr_pages = 0;
- struct page *page;
- pgoff_t index;
- struct blk_plug plug;
-
- for (index = start_index; index < start_index + count; index++) {
- page = xa_load(&mapping->i_pages, index);
- if (!page || xa_is_value(page)) {
- page = __page_cache_alloc(readahead_gfp_mask(mapping));
- if (!page)
- break;
- page->index = index;
- list_add(&page->lru, &pages);
- nr_pages++;
- }
- }
- blk_start_plug(&plug);
- ext4_mpage_readpages(mapping, &pages, NULL, nr_pages, true);
- blk_finish_plug(&plug);
-}
-
static struct page *ext4_read_merkle_tree_page(struct inode *inode,
pgoff_t index,
unsigned long num_ra_pages)
@@ -386,8 +355,8 @@ static struct page *ext4_read_merkle_tre
if (page)
put_page(page);
else if (num_ra_pages > 1)
- ext4_merkle_tree_readahead(inode->i_mapping, index,
- num_ra_pages);
+ page_cache_readahead_unbounded(inode->i_mapping, NULL,
+ index, num_ra_pages, 0);
page = read_mapping_page(inode->i_mapping, index, NULL);
}
return page;
--- a/fs/f2fs/data.c~mm-add-page_cache_readahead_unbounded
+++ a/fs/f2fs/data.c
@@ -2177,7 +2177,7 @@ out:
* use ->readpage() or do the necessary surgery to decouple ->readpages()
* from read-ahead.
*/
-int f2fs_mpage_readpages(struct address_space *mapping,
+static int f2fs_mpage_readpages(struct address_space *mapping,
struct list_head *pages, struct page *page,
unsigned nr_pages, bool is_readahead)
{
--- a/fs/f2fs/f2fs.h~mm-add-page_cache_readahead_unbounded
+++ a/fs/f2fs/f2fs.h
@@ -3373,9 +3373,6 @@ int f2fs_reserve_new_block(struct dnode_
int f2fs_get_block(struct dnode_of_data *dn, pgoff_t index);
int f2fs_preallocate_blocks(struct kiocb *iocb, struct iov_iter *from);
int f2fs_reserve_block(struct dnode_of_data *dn, pgoff_t index);
-int f2fs_mpage_readpages(struct address_space *mapping,
- struct list_head *pages, struct page *page,
- unsigned nr_pages, bool is_readahead);
struct page *f2fs_get_read_data_page(struct inode *inode, pgoff_t index,
int op_flags, bool for_write);
struct page *f2fs_find_data_page(struct inode *inode, pgoff_t index);
--- a/fs/f2fs/verity.c~mm-add-page_cache_readahead_unbounded
+++ a/fs/f2fs/verity.c
@@ -222,37 +222,6 @@ static int f2fs_get_verity_descriptor(st
return size;
}
-/*
- * Prefetch some pages from the file's Merkle tree.
- *
- * This is basically a stripped-down version of __do_page_cache_readahead()
- * which works on pages past i_size.
- */
-static void f2fs_merkle_tree_readahead(struct address_space *mapping,
- pgoff_t start_index, unsigned long count)
-{
- LIST_HEAD(pages);
- unsigned int nr_pages = 0;
- struct page *page;
- pgoff_t index;
- struct blk_plug plug;
-
- for (index = start_index; index < start_index + count; index++) {
- page = xa_load(&mapping->i_pages, index);
- if (!page || xa_is_value(page)) {
- page = __page_cache_alloc(readahead_gfp_mask(mapping));
- if (!page)
- break;
- page->index = index;
- list_add(&page->lru, &pages);
- nr_pages++;
- }
- }
- blk_start_plug(&plug);
- f2fs_mpage_readpages(mapping, &pages, NULL, nr_pages, true);
- blk_finish_plug(&plug);
-}
-
static struct page *f2fs_read_merkle_tree_page(struct inode *inode,
pgoff_t index,
unsigned long num_ra_pages)
@@ -266,8 +235,8 @@ static struct page *f2fs_read_merkle_tre
if (page)
put_page(page);
else if (num_ra_pages > 1)
- f2fs_merkle_tree_readahead(inode->i_mapping, index,
- num_ra_pages);
+ page_cache_readahead_unbounded(inode->i_mapping, NULL,
+ index, num_ra_pages, 0);
page = read_mapping_page(inode->i_mapping, index, NULL);
}
return page;
--- a/include/linux/pagemap.h~mm-add-page_cache_readahead_unbounded
+++ a/include/linux/pagemap.h
@@ -622,6 +622,9 @@ void page_cache_sync_readahead(struct ad
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_readahead_unbounded(struct address_space *, struct file *,
+ pgoff_t index, unsigned long nr_to_read,
+ unsigned long lookahead_count);
/*
* Like add_to_page_cache_locked, but used to add newly allocated pages:
--- a/mm/readahead.c~mm-add-page_cache_readahead_unbounded
+++ a/mm/readahead.c
@@ -156,37 +156,34 @@ out:
rac->_index++;
}
-/*
- * __do_page_cache_readahead() 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.
+/**
+ * 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.
+ * @nr_to_read: The number of pages to read.
+ * @lookahead_size: Where to start the next readahead.
+ *
+ * This function is for filesystems to call when they want to start
+ * readahead beyond a file's stated i_size. This is almost certainly
+ * not the function you want to call. Use page_cache_async_readahead()
+ * or page_cache_sync_readahead() instead.
+ *
+ * Context: File is referenced by caller. Mutexes may be held by caller.
+ * May sleep, but will not reenter filesystem to reclaim memory.
*/
-void __do_page_cache_readahead(struct address_space *mapping,
- struct file *filp, pgoff_t index, unsigned long nr_to_read,
+void page_cache_readahead_unbounded(struct address_space *mapping,
+ struct file *file, pgoff_t index, unsigned long nr_to_read,
unsigned long lookahead_size)
{
- struct inode *inode = mapping->host;
LIST_HEAD(page_pool);
- loff_t isize = i_size_read(inode);
gfp_t gfp_mask = readahead_gfp_mask(mapping);
struct readahead_control rac = {
.mapping = mapping,
- .file = filp,
+ .file = file,
._index = index,
};
unsigned long i;
- pgoff_t end_index; /* The last page we want to read */
-
- if (isize == 0)
- return;
-
- end_index = (isize - 1) >> PAGE_SHIFT;
- if (index > end_index)
- return;
- /* Don't read past the page containing the last byte of the file */
- if (nr_to_read > end_index - index)
- nr_to_read = end_index - index + 1;
/*
* Preallocate as many pages as we will need.
@@ -230,6 +227,35 @@ void __do_page_cache_readahead(struct ad
*/
read_pages(&rac, &page_pool, false);
}
+EXPORT_SYMBOL_GPL(page_cache_readahead_unbounded);
+
+/*
+ * __do_page_cache_readahead() 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)
+{
+ struct inode *inode = mapping->host;
+ loff_t isize = i_size_read(inode);
+ pgoff_t end_index; /* The last page we want to read */
+
+ if (isize == 0)
+ return;
+
+ end_index = (isize - 1) >> PAGE_SHIFT;
+ if (index > end_index)
+ return;
+ /* Don't read past the page containing the last byte of the file */
+ 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);
+}
/*
* Chunk the readahead into 2 megabyte units, so that we don't pin too much
_
Patches currently in -mm which might be from willy@xxxxxxxxxxxxx are
mm-move-readahead-prototypes-from-mmh.patch
mm-return-void-from-various-readahead-functions.patch
mm-ignore-return-value-of-readpages.patch
mm-move-readahead-nr_pages-check-into-read_pages.patch
mm-add-new-readahead_control-api.patch
mm-use-readahead_control-to-pass-arguments.patch
mm-rename-various-offset-parameters-to-index.patch
mm-rename-readahead-loop-variable-to-i.patch
mm-remove-page_offset-from-readahead-loop.patch
mm-put-readahead-pages-in-cache-earlier.patch
mm-add-readahead-address-space-operation.patch
mm-move-end_index-check-out-of-readahead-loop.patch
mm-add-page_cache_readahead_unbounded.patch
mm-document-why-we-dont-set-pagereadahead.patch
mm-use-memalloc_nofs_save-in-readahead-path.patch
fs-convert-mpage_readpages-to-mpage_readahead.patch
btrfs-convert-from-readpages-to-readahead.patch
erofs-convert-uncompressed-files-from-readpages-to-readahead.patch
erofs-convert-compressed-files-from-readpages-to-readahead.patch
ext4-convert-from-readpages-to-readahead.patch
ext4-pass-the-inode-to-ext4_mpage_readpages.patch
f2fs-convert-from-readpages-to-readahead.patch
f2fs-pass-the-inode-to-f2fs_mpage_readpages.patch
fuse-convert-from-readpages-to-readahead.patch
iomap-convert-from-readpages-to-readahead.patch
