mm: move readahead prototypes from mm.h

Patch series "Change readahead API", v11.

This series adds a readahead address_space operation to replace the
readpages operation.  The key difference is that pages are added to the
page cache as they are allocated (and then looked up by the filesystem)
instead of passing them on a list to the readpages operation and having
the filesystem add them to the page cache.  It's a net reduction in code
for each implementation, more efficient than walking a list, and solves
the direct-write vs buffered-read problem reported by yu kuai at
http://lkml.kernel.org/r/20200116063601.39201-1-yukuai3@huawei.com

The only unconverted filesystems are those which use fscache.  Their
conversion is pending Dave Howells' rewrite which will make the
conversion substantially easier.  This should be completed by the end of
the year.

I want to thank the reviewers/testers; Dave Chinner, John Hubbard, Eric
Biggers, Johannes Thumshirn, Dave Sterba, Zi Yan, Christoph Hellwig and
Miklos Szeredi have done a marvellous job of providing constructive
criticism.

These patches pass an xfstests run on ext4, xfs & btrfs with no
regressions that I can tell (some of the tests seem a little flaky
before and remain flaky afterwards).

This patch (of 25):

The readahead code is part of the page cache so should be found in the
pagemap.h file.  force_page_cache_readahead is only used within mm, so
move it to mm/internal.h instead.  Remove the parameter names where they
add no value, and rename the ones which were actively misleading.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Cc: Chao Yu <yuchao0@huawei.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Gao Xiang <gaoxiang25@huawei.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Miklos Szeredi <mszeredi@redhat.com>
Link: http://lkml.kernel.org/r/20200414150233.24495-1-willy@infradead.org
Link: http://lkml.kernel.org/r/20200414150233.24495-2-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/block/blk-core.c b/block/blk-core.c
index 9bfaee050c825f2ccb16981f693b4cc16f7557a9..38d7b1f160673405b1ac9c57a459d1dd6f0ceb11 100644 (file)
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -20,6 +20,7 @@
 #include <linux/blk-mq.h>
 #include <linux/highmem.h>
 #include <linux/mm.h>
+#include <linux/pagemap.h>
 #include <linux/kernel_stat.h>
 #include <linux/string.h>
 #include <linux/init.h>

diff --git a/include/linux/mm.h b/include/linux/mm.h
index f3fe7371855cec8769fbee500632d52c05cf4610..92704fde64757ebb6abe2202ef6d03c2eb35c210 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2612,25 +2612,6 @@ extern vm_fault_t filemap_page_mkwrite(struct vm_fault *vmf);
 int __must_check write_one_page(struct page *page);
 void task_dirty_inc(struct task_struct *tsk);
 
-/* readahead.c */
-#define VM_READAHEAD_PAGES     (SZ_128K / PAGE_SIZE)
-
-int force_page_cache_readahead(struct address_space *mapping, struct file *filp,
-                       pgoff_t offset, unsigned long nr_to_read);
-
-void page_cache_sync_readahead(struct address_space *mapping,
-                              struct file_ra_state *ra,
-                              struct file *filp,
-                              pgoff_t offset,
-                              unsigned long size);
-
-void page_cache_async_readahead(struct address_space *mapping,
-                               struct file_ra_state *ra,
-                               struct file *filp,
-                               struct page *pg,
-                               pgoff_t offset,
-                               unsigned long size);
-
 extern unsigned long stack_guard_gap;
 /* Generic expand stack which grows the stack according to GROWS{UP,DOWN} */
 extern int expand_stack(struct vm_area_struct *vma, unsigned long address);

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index d4409b13747e8c7ea8a62d85476fde58603c8e98..8c081cda4b35b0fa602fc1fff1a0f64475e02eaf 100644 (file)
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -618,6 +618,14 @@ int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask);
 void delete_from_page_cache_batch(struct address_space *mapping,
                                  struct pagevec *pvec);
 
+#define VM_READAHEAD_PAGES     (SZ_128K / PAGE_SIZE)
+
+void page_cache_sync_readahead(struct address_space *, struct file_ra_state *,
+               struct file *, pgoff_t index, unsigned long req_count);
+void page_cache_async_readahead(struct address_space *, struct file_ra_state *,
+               struct file *, struct page *, pgoff_t index,
+               unsigned long req_count);
+
 /*
  * Like add_to_page_cache_locked, but used to add newly allocated pages:
  * the page is new, so we can just run __SetPageLocked() against it.

diff --git a/mm/fadvise.c b/mm/fadvise.c
index 4f17c83db5758d03bc06e05e38a60357ad593434..3efebfb9952c2bcff6650437b703aae4cfc4870e 100644 (file)
--- a/mm/fadvise.c
+++ b/mm/fadvise.c
@@ -22,6 +22,8 @@
 
 #include <asm/unistd.h>
 
+#include "internal.h"
+
 /*
  * POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could
  * deactivate the pages and clear PG_Referenced.

diff --git a/mm/internal.h b/mm/internal.h
index b5634e78f01dc6aa49b0c6926ba444b69c5fcadc..25fee17c733469f5f5131f4cbc504898c4b8bbbe 100644 (file)
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -49,6 +49,8 @@ void unmap_page_range(struct mmu_gather *tlb,
                             unsigned long addr, unsigned long end,
                             struct zap_details *details);
 
+int force_page_cache_readahead(struct address_space *, struct file *,
+               pgoff_t index, unsigned long nr_to_read);
 extern unsigned int __do_page_cache_readahead(struct address_space *mapping,
                struct file *filp, pgoff_t offset, unsigned long nr_to_read,
                unsigned long lookahead_size);