filemap: add a kiocb_write_and_wait helper

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

Link: https://lkml.kernel.org/r/20230601145904.1385409-5-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Acked-by: Darrick J. Wong <djwong@kernel.org>
Cc: Al 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: Ilya Dryomov <idryomov@gmail.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Miklos Szeredi <mszeredi@redhat.com>
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>

diff --git a/block/fops.c b/block/fops.c
index 58d0aeb..5751710 100644 (file)
--- a/block/fops.c
+++ b/block/fops.c
@@ -576,21 +576,9 @@ static ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
                goto reexpand; /* skip atime */
 
        if (iocb->ki_flags & IOCB_DIRECT) {
-               struct address_space *mapping = iocb->ki_filp->f_mapping;
-
-               if (iocb->ki_flags & IOCB_NOWAIT) {
-                       if (filemap_range_needs_writeback(mapping, pos,
-                                                         pos + count - 1)) {
-                               ret = -EAGAIN;
-                               goto reexpand;
-                       }
-               } else {
-                       ret = filemap_write_and_wait_range(mapping, pos,
-                                                          pos + count - 1);
-                       if (ret < 0)
-                               goto reexpand;
-               }
-
+               ret = kiocb_write_and_wait(iocb, count);
+               if (ret < 0)
+                       goto reexpand;
                file_accessed(iocb->ki_filp);
 
                ret = blkdev_direct_IO(iocb, to);

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index c1ae5eb..b6a12ca 100644 (file)
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -30,6 +30,7 @@ static inline void invalidate_remote_inode(struct inode *inode)
 int invalidate_inode_pages2(struct address_space *mapping);
 int invalidate_inode_pages2_range(struct address_space *mapping,
                pgoff_t start, pgoff_t end);
+
 int write_inode_now(struct inode *, int sync);
 int filemap_fdatawrite(struct address_space *);
 int filemap_flush(struct address_space *);
@@ -54,6 +55,7 @@ int filemap_check_errors(struct address_space *mapping);
 void __filemap_set_wb_err(struct address_space *mapping, int err);
 int filemap_fdatawrite_wbc(struct address_space *mapping,
                           struct writeback_control *wbc);
+int kiocb_write_and_wait(struct kiocb *iocb, size_t count);
 
 static inline int filemap_write_and_wait(struct address_space *mapping)
 {

diff --git a/mm/filemap.c b/mm/filemap.c
index 3a80a69..5566e10 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2735,6 +2735,21 @@ put_folios:
 }
 EXPORT_SYMBOL_GPL(filemap_read);
 
+int kiocb_write_and_wait(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;
+
+       if (iocb->ki_flags & IOCB_NOWAIT) {
+               if (filemap_range_needs_writeback(mapping, pos, end))
+                       return -EAGAIN;
+               return 0;
+       }
+
+       return filemap_write_and_wait_range(mapping, pos, end);
+}
+
 /**
  * generic_file_read_iter - generic filesystem read routine
  * @iocb:      kernel I/O control block
@@ -2770,18 +2785,9 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
                struct address_space *mapping = file->f_mapping;
                struct inode *inode = mapping->host;
 
-               if (iocb->ki_flags & IOCB_NOWAIT) {
-                       if (filemap_range_needs_writeback(mapping, iocb->ki_pos,
-                                               iocb->ki_pos + count - 1))
-                               return -EAGAIN;
-               } else {
-                       retval = filemap_write_and_wait_range(mapping,
-                                               iocb->ki_pos,
-                                               iocb->ki_pos + count - 1);
-                       if (retval < 0)
-                               return retval;
-               }
-
+               retval = kiocb_write_and_wait(iocb, count);
+               if (retval < 0)
+                       return retval;
                file_accessed(file);
 
                retval = mapping->a_ops->direct_IO(iocb, iter);