The patch titled
Subject: iomap: convert from readpages to readahead
has been added to the -mm tree. Its filename is
iomap-convert-from-readpages-to-readahead.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/iomap-convert-from-readpages-to-readahead.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/iomap-convert-from-readpages-to-readahead.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Subject: iomap: convert from readpages to readahead
Use the new readahead operation in iomap. Convert XFS and ZoneFS to use
it.
Link: http://lkml.kernel.org/r/20200414150233.24495-26-willy@xxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Reviewed-by: William Kucharski <william.kucharski@xxxxxxxxxx>
Cc: Chao Yu <yuchao0@xxxxxxxxxx>
Cc: Cong Wang <xiyou.wangcong@xxxxxxxxx>
Cc: Dave Chinner <dchinner@xxxxxxxxxx>
Cc: Eric Biggers <ebiggers@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/iomap/buffered-io.c | 92 +++++++++++++--------------------------
fs/iomap/trace.h | 2
fs/xfs/xfs_aops.c | 13 ++---
fs/zonefs/super.c | 7 +-
include/linux/iomap.h | 3 -
5 files changed, 42 insertions(+), 75 deletions(-)
--- a/fs/iomap/buffered-io.c~iomap-convert-from-readpages-to-readahead
+++ a/fs/iomap/buffered-io.c
@@ -214,9 +214,8 @@ iomap_read_end_io(struct bio *bio)
struct iomap_readpage_ctx {
struct page *cur_page;
bool cur_page_in_bio;
- bool is_readahead;
struct bio *bio;
- struct list_head *pages;
+ struct readahead_control *rac;
};
static void
@@ -308,7 +307,7 @@ iomap_readpage_actor(struct inode *inode
if (ctx->bio)
submit_bio(ctx->bio);
- if (ctx->is_readahead) /* same as readahead_gfp_mask */
+ if (ctx->rac) /* same as readahead_gfp_mask */
gfp |= __GFP_NORETRY | __GFP_NOWARN;
ctx->bio = bio_alloc(gfp, min(BIO_MAX_PAGES, nr_vecs));
/*
@@ -319,7 +318,7 @@ iomap_readpage_actor(struct inode *inode
if (!ctx->bio)
ctx->bio = bio_alloc(orig_gfp, 1);
ctx->bio->bi_opf = REQ_OP_READ;
- if (ctx->is_readahead)
+ if (ctx->rac)
ctx->bio->bi_opf |= REQ_RAHEAD;
ctx->bio->bi_iter.bi_sector = sector;
bio_set_dev(ctx->bio, iomap->bdev);
@@ -375,36 +374,8 @@ iomap_readpage(struct page *page, const
}
EXPORT_SYMBOL_GPL(iomap_readpage);
-static struct page *
-iomap_next_page(struct inode *inode, struct list_head *pages, loff_t pos,
- loff_t length, loff_t *done)
-{
- while (!list_empty(pages)) {
- struct page *page = lru_to_page(pages);
-
- if (page_offset(page) >= (u64)pos + length)
- break;
-
- list_del(&page->lru);
- if (!add_to_page_cache_lru(page, inode->i_mapping, page->index,
- GFP_NOFS))
- return page;
-
- /*
- * If we already have a page in the page cache at index we are
- * done. Upper layers don't care if it is uptodate after the
- * readpages call itself as every page gets checked again once
- * actually needed.
- */
- *done += PAGE_SIZE;
- put_page(page);
- }
-
- return NULL;
-}
-
static loff_t
-iomap_readpages_actor(struct inode *inode, loff_t pos, loff_t length,
+iomap_readahead_actor(struct inode *inode, loff_t pos, loff_t length,
void *data, struct iomap *iomap, struct iomap *srcmap)
{
struct iomap_readpage_ctx *ctx = data;
@@ -418,10 +389,7 @@ iomap_readpages_actor(struct inode *inod
ctx->cur_page = NULL;
}
if (!ctx->cur_page) {
- ctx->cur_page = iomap_next_page(inode, ctx->pages,
- pos, length, &done);
- if (!ctx->cur_page)
- break;
+ ctx->cur_page = readahead_page(ctx->rac);
ctx->cur_page_in_bio = false;
}
ret = iomap_readpage_actor(inode, pos + done, length - done,
@@ -431,32 +399,43 @@ iomap_readpages_actor(struct inode *inod
return done;
}
-int
-iomap_readpages(struct address_space *mapping, struct list_head *pages,
- unsigned nr_pages, const struct iomap_ops *ops)
-{
+/**
+ * iomap_readahead - Attempt to read pages from a file.
+ * @rac: Describes the pages to be read.
+ * @ops: The operations vector for the filesystem.
+ *
+ * This function is for filesystems to call to implement their readahead
+ * address_space operation.
+ *
+ * Context: The @ops callbacks may submit I/O (eg to read the addresses of
+ * blocks from disc), and may wait for it. The caller may be trying to
+ * access a different page, and so sleeping excessively should be avoided.
+ * It may allocate memory, but should avoid costly allocations. This
+ * function is called with memalloc_nofs set, so allocations will not cause
+ * the filesystem to be reentered.
+ */
+void iomap_readahead(struct readahead_control *rac, const struct iomap_ops *ops)
+{
+ struct inode *inode = rac->mapping->host;
+ loff_t pos = readahead_pos(rac);
+ loff_t length = readahead_length(rac);
struct iomap_readpage_ctx ctx = {
- .pages = pages,
- .is_readahead = true,
+ .rac = rac,
};
- loff_t pos = page_offset(list_entry(pages->prev, struct page, lru));
- loff_t last = page_offset(list_entry(pages->next, struct page, lru));
- loff_t length = last - pos + PAGE_SIZE, ret = 0;
- trace_iomap_readpages(mapping->host, nr_pages);
+ trace_iomap_readahead(inode, readahead_count(rac));
while (length > 0) {
- ret = iomap_apply(mapping->host, pos, length, 0, ops,
- &ctx, iomap_readpages_actor);
+ loff_t ret = iomap_apply(inode, pos, length, 0, ops,
+ &ctx, iomap_readahead_actor);
if (ret <= 0) {
WARN_ON_ONCE(ret == 0);
- goto done;
+ break;
}
pos += ret;
length -= ret;
}
- ret = 0;
-done:
+
if (ctx.bio)
submit_bio(ctx.bio);
if (ctx.cur_page) {
@@ -464,15 +443,8 @@ done:
unlock_page(ctx.cur_page);
put_page(ctx.cur_page);
}
-
- /*
- * Check that we didn't lose a page due to the arcance calling
- * conventions..
- */
- WARN_ON_ONCE(!ret && !list_empty(ctx.pages));
- return ret;
}
-EXPORT_SYMBOL_GPL(iomap_readpages);
+EXPORT_SYMBOL_GPL(iomap_readahead);
/*
* iomap_is_partially_uptodate checks whether blocks within a page are
--- a/fs/iomap/trace.h~iomap-convert-from-readpages-to-readahead
+++ a/fs/iomap/trace.h
@@ -39,7 +39,7 @@ DEFINE_EVENT(iomap_readpage_class, name,
TP_PROTO(struct inode *inode, int nr_pages), \
TP_ARGS(inode, nr_pages))
DEFINE_READPAGE_EVENT(iomap_readpage);
-DEFINE_READPAGE_EVENT(iomap_readpages);
+DEFINE_READPAGE_EVENT(iomap_readahead);
DECLARE_EVENT_CLASS(iomap_range_class,
TP_PROTO(struct inode *inode, unsigned long off, unsigned int len),
--- a/fs/xfs/xfs_aops.c~iomap-convert-from-readpages-to-readahead
+++ a/fs/xfs/xfs_aops.c
@@ -621,14 +621,11 @@ xfs_vm_readpage(
return iomap_readpage(page, &xfs_read_iomap_ops);
}
-STATIC int
-xfs_vm_readpages(
- struct file *unused,
- struct address_space *mapping,
- struct list_head *pages,
- unsigned nr_pages)
+STATIC void
+xfs_vm_readahead(
+ struct readahead_control *rac)
{
- return iomap_readpages(mapping, pages, nr_pages, &xfs_read_iomap_ops);
+ iomap_readahead(rac, &xfs_read_iomap_ops);
}
static int
@@ -644,7 +641,7 @@ xfs_iomap_swapfile_activate(
const struct address_space_operations xfs_address_space_operations = {
.readpage = xfs_vm_readpage,
- .readpages = xfs_vm_readpages,
+ .readahead = xfs_vm_readahead,
.writepage = xfs_vm_writepage,
.writepages = xfs_vm_writepages,
.set_page_dirty = iomap_set_page_dirty,
--- a/fs/zonefs/super.c~iomap-convert-from-readpages-to-readahead
+++ a/fs/zonefs/super.c
@@ -78,10 +78,9 @@ static int zonefs_readpage(struct file *
return iomap_readpage(page, &zonefs_iomap_ops);
}
-static int zonefs_readpages(struct file *unused, struct address_space *mapping,
- struct list_head *pages, unsigned int nr_pages)
+static void zonefs_readahead(struct readahead_control *rac)
{
- return iomap_readpages(mapping, pages, nr_pages, &zonefs_iomap_ops);
+ iomap_readahead(rac, &zonefs_iomap_ops);
}
/*
@@ -128,7 +127,7 @@ static int zonefs_writepages(struct addr
static const struct address_space_operations zonefs_file_aops = {
.readpage = zonefs_readpage,
- .readpages = zonefs_readpages,
+ .readahead = zonefs_readahead,
.writepage = zonefs_writepage,
.writepages = zonefs_writepages,
.set_page_dirty = iomap_set_page_dirty,
--- a/include/linux/iomap.h~iomap-convert-from-readpages-to-readahead
+++ a/include/linux/iomap.h
@@ -155,8 +155,7 @@ loff_t iomap_apply(struct inode *inode,
ssize_t iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *from,
const struct iomap_ops *ops);
int iomap_readpage(struct page *page, const struct iomap_ops *ops);
-int iomap_readpages(struct address_space *mapping, struct list_head *pages,
- unsigned nr_pages, const struct iomap_ops *ops);
+void iomap_readahead(struct readahead_control *, const struct iomap_ops *ops);
int iomap_set_page_dirty(struct page *page);
int iomap_is_partially_uptodate(struct page *page, unsigned long from,
unsigned long count);
_
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
