+ filemap-add-a-kiocb_invalidate_pages-helper.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: filemap: add a kiocb_invalidate_pages helper
has been added to the -mm mm-unstable branch.  Its filename is
     filemap-add-a-kiocb_invalidate_pages-helper.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/filemap-add-a-kiocb_invalidate_pages-helper.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Christoph Hellwig <hch@lst.de>
Subject: filemap: add a kiocb_invalidate_pages helper
Date: Fri, 19 May 2023 11:35:13 +0200

Factor out a helper that calls filemap_write_and_wait_range and
invalidate_inode_pages2_rangefor a the range covered by a write kiocb or
returns -EAGAIN if the kiocb is marked as nowait and there would be pages
to write or invalidate.

Link: https://lkml.kernel.org/r/20230519093521.133226-6-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Anna Schumaker <anna@kernel.org>
Cc: Chao Yu <chao@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Damien Le Moal <dlemoal@kernel.org>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Ilya Dryomov <idryomov@gmail.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/pagemap.h |    1 
 mm/filemap.c            |   48 ++++++++++++++++++++++----------------
 2 files changed, 29 insertions(+), 20 deletions(-)

--- a/include/linux/pagemap.h~filemap-add-a-kiocb_invalidate_pages-helper
+++ a/include/linux/pagemap.h
@@ -30,6 +30,7 @@ static inline void invalidate_remote_ino
 int invalidate_inode_pages2(struct address_space *mapping);
 int invalidate_inode_pages2_range(struct address_space *mapping,
 		pgoff_t start, pgoff_t end);
+int kiocb_invalidate_pages(struct kiocb *iocb, size_t count);
 
 int write_inode_now(struct inode *, int sync);
 int filemap_fdatawrite(struct address_space *);
--- a/mm/filemap.c~filemap-add-a-kiocb_invalidate_pages-helper
+++ a/mm/filemap.c
@@ -2750,6 +2750,33 @@ int kiocb_write_and_wait(struct kiocb *i
 	return filemap_write_and_wait_range(mapping, pos, end);
 }
 
+int kiocb_invalidate_pages(struct kiocb *iocb, size_t count)
+{
+	struct address_space *mapping = iocb->ki_filp->f_mapping;
+	loff_t pos = iocb->ki_pos;
+	loff_t end = pos + count - 1;
+	int ret;
+
+	if (iocb->ki_flags & IOCB_NOWAIT) {
+		/* we could block if there are any pages in the range */
+		if (filemap_range_has_page(mapping, pos, end))
+			return -EAGAIN;
+	} else {
+		ret = filemap_write_and_wait_range(mapping, pos, end);
+		if (ret)
+			return ret;
+	}
+
+	/*
+	 * After a write we want buffered reads to be sure to go to disk to get
+	 * the new data.  We invalidate clean cached page from the region we're
+	 * about to write.  We do this *before* the write so that we can return
+	 * without clobbering -EIOCBQUEUED from ->direct_IO().
+	 */
+	return invalidate_inode_pages2_range(mapping, pos >> PAGE_SHIFT,
+					     end >> PAGE_SHIFT);
+}
+
 /**
  * generic_file_read_iter - generic filesystem read routine
  * @iocb:	kernel I/O control block
@@ -3793,30 +3820,11 @@ generic_file_direct_write(struct kiocb *
 	write_len = iov_iter_count(from);
 	end = (pos + write_len - 1) >> PAGE_SHIFT;
 
-	if (iocb->ki_flags & IOCB_NOWAIT) {
-		/* If there are pages to writeback, return */
-		if (filemap_range_has_page(file->f_mapping, pos,
-					   pos + write_len - 1))
-			return -EAGAIN;
-	} else {
-		written = filemap_write_and_wait_range(mapping, pos,
-							pos + write_len - 1);
-		if (written)
-			goto out;
-	}
-
-	/*
-	 * After a write we want buffered reads to be sure to go to disk to get
-	 * the new data.  We invalidate clean cached page from the region we're
-	 * about to write.  We do this *before* the write so that we can return
-	 * without clobbering -EIOCBQUEUED from ->direct_IO().
-	 */
-	written = invalidate_inode_pages2_range(mapping,
-					pos >> PAGE_SHIFT, end);
 	/*
 	 * If a page can not be invalidated, return 0 to fall back
 	 * to buffered write.
 	 */
+	written = kiocb_invalidate_pages(iocb, write_len);
 	if (written) {
 		if (written == -EBUSY)
 			return 0;
_

Patches currently in -mm which might be from hch@lst.de are

iomap-update-ki_pos-a-little-later-in-iomap_dio_complete.patch
filemap-update-ki_pos-in-generic_perform_write.patch
filemap-assign-current-backing_dev_info-in-generic_perform_write.patch
filemap-add-a-kiocb_write_and_wait-helper.patch
filemap-add-a-kiocb_invalidate_pages-helper.patch
filemap-add-a-kiocb_invalidate_post_write-helper.patch
iomap-update-ki_pos-in-iomap_file_buffered_write.patch
iomap-assign-current-backing_dev_info-in-iomap_file_buffered_write.patch
iomap-use-kiocb_write_and_wait-and-kiocb_invalidate_pages.patch
fs-factor-out-a-direct_write_fallback-helper.patch
fuse-update-ki_pos-in-fuse_perform_write.patch
fuse-drop-redundant-arguments-to-fuse_perform_write.patch
fuse-use-direct_write_fallback.patch
squashfs-dont-include-buffer_headh.patch